Adding upstream version 2.117.0.upstream/2.117.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

477 files changed, 79487 insertions, 0 deletions

diff --git a/lib/Lintian/Archive.pm b/lib/Lintian/Archive.pm
new file mode 100644
index 0000000..b9652af
--- /dev/null
+++ b/lib/Lintian/Archive.pm
@@ -0,0 +1,179 @@
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Archive;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use IPC::Run3;
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+const my $SLASH => q{/};
+
+const my $WAIT_STATUS_SHIFT => 8;
+
+=head1 NAME
+
+Lintian::Archive -- Facilities for archive data
+
+=head1 SYNOPSIS
+
+use Lintian::Archive;
+
+=head1 DESCRIPTION
+
+A class for downloading and accessing archive information
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item mirror_base
+
+=item work_folder
+
+=item packages
+
+=cut
+
+has mirror_base => (is => 'rw', default => 'https://deb.debian.org/debian');
+
+has work_folder => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $work_folder
+          = Path::Tiny->tempdir(TEMPLATE => 'lintian-archive-XXXXXXXXXX');
+
+        return $work_folder;
+    }
+);
+
+has packages => (is => 'rw', default => sub { {} });
+
+=item contents_gz
+
+=cut
+
+sub contents_gz {
+    my ($self, $release, $archive_liberty, $installable_architecture) = @_;
+
+    my $relative
+      = "$release/$archive_liberty/Contents-$installable_architecture.gz";
+    my $local_path = $self->work_folder . $SLASH . $relative;
+
+    return $local_path
+      if -e $local_path;
+
+    path($local_path)->parent->mkpath;
+
+    my $url = $self->mirror_base . "/dists/$relative";
+
+    my $stderr;
+    run3([qw{wget --quiet}, "--output-document=$local_path", $url],
+        undef, \$stderr);
+    my $status = ($? >> $WAIT_STATUS_SHIFT);
+
+    # stderr already in UTF-8
+    die $stderr
+      if $status;
+
+    return $local_path;
+}
+
+=item deb822_packages_by_installable_name
+
+=cut
+
+sub deb822_packages_by_installable_name {
+    my ($self, $release, $archive_liberty, $port) = @_;
+
+    return $self->packages->{$release}{$archive_liberty}{$port}
+      if exists $self->packages->{$release}{$archive_liberty}{$port};
+
+    my $relative_unzipped = "$release/$archive_liberty/binary-$port/Packages";
+    my $local_path = $self->work_folder . $SLASH . $relative_unzipped;
+
+    path($local_path)->parent->mkpath;
+
+    my $url = $self->mirror_base . "/dists/$relative_unzipped.gz";
+
+    my $stderr;
+
+    run3([qw{wget --quiet}, "--output-document=$local_path.gz", $url],
+        undef, \$stderr);
+    my $status = ($? >> $WAIT_STATUS_SHIFT);
+
+    # stderr already in UTF-8
+    die $stderr
+      if $status;
+
+    run3(['gunzip', "$local_path.gz"], undef, \$stderr);
+    $status = ($? >> $WAIT_STATUS_SHIFT);
+
+    # stderr already in UTF-8
+    die $stderr
+      if $status;
+
+    my $deb822 = Lintian::Deb822->new;
+    my @sections = $deb822->read_file($local_path);
+
+    unlink($local_path)
+      or die encode_utf8("Cannot delete $local_path");
+
+    my %section_by_installable_name;
+    for my $section (@sections) {
+
+        my $installable_name = $section->value('Package');
+        $section_by_installable_name{$installable_name} = $section;
+    }
+
+    $self->packages->{$release}{$archive_liberty}{$port}
+      = \%section_by_installable_name;
+
+    return \%section_by_installable_name;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Changelog.pm b/lib/Lintian/Changelog.pm
new file mode 100644
index 0000000..84854c3
--- /dev/null
+++ b/lib/Lintian/Changelog.pm
@@ -0,0 +1,380 @@
+# Copyright (C) 2019 Felix Lechner <felix.lechner@lease-up.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Changelog;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp;
+use Const::Fast;
+use Date::Parse;
+
+use Lintian::Changelog::Entry;
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $ASTERISK => q{*};
+const my $UNKNOWN => q{unknown};
+
+use Moo;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Changelog -- Parse a literal version string into its constituents
+
+=head1 SYNOPSIS
+
+ use Lintian::Changelog;
+
+ my $version = Lintian::Changelog->new;
+ $version->set('1.2.3-4', undef);
+
+=head1 DESCRIPTION
+
+A class for parsing literal version strings
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item new ()
+
+Creates a new Lintian::Changelog object.
+
+=cut
+
+=item find_closes
+
+Takes one string as argument and finds "Closes: #123456, #654321" statements
+as supported by the Debian Archive software in it. Returns all closed bug
+numbers in an array reference.
+
+=cut
+
+sub find_closes {
+    my $changes = shift;
+    my @closes = ();
+
+    while (
+        $changes
+        && ($changes
+            =~ /(closes:\s*(?:bug)?\#?\s?\d+(?:,\s*(?:bug)?\#?\s?\d+)*)/ig)
+    ) {
+        push(@closes, $1 =~ /\#?\s?(\d+)/g);
+    }
+
+    @closes = sort { $a <=> $b } @closes;
+    return \@closes;
+}
+
+=back
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item parse (STRING)
+
+Parses STRING as the content of a debian/changelog file.
+
+=cut
+
+sub parse {
+    my ($self, $contents) = @_;
+
+    $self->errors([]);
+    $self->entries([]);
+
+    # careful with negative matching /m
+    unless (
+        $contents =~ m{^ \S+ \s* [(] [^\)]+ [)] \s* (?:[^ \t;]+ \s*)+ ; }mx) {
+
+        push(@{$self->errors}, [1, 'not a Debian changelog']);
+        return;
+    }
+
+    my @lines = split(/\n/, $contents);
+
+    # based on /usr/lib/dpkg/parsechangelog/debian
+    my $expect='first heading';
+    my $entry = Lintian::Changelog::Entry->new;
+    my $blanklines = 0;
+
+    # to make unknown version unique, for id
+    my $unknown_version_counter = 1;
+
+    my $position = 1;
+    for my $line (@lines) {
+
+        # trim end
+        $line =~ s/\s+\r?$//;
+
+      #	print encode_utf*(sprintf(STDERR "%-39.39s %-39.39s\n",$expect,$line));
+        if ($line
+            =~ m/^(?<Source>\w[-+0-9a-z.]*) \((?<Version>[^\(\) \t]+)\)(?<Distribution>(?:\s+[-+0-9a-z.]+)+)\;\s*(?<kvpairs>.*)$/i
+        ){
+            my $source = $+{Source};
+            my $version = $+{Version};
+            my $distribution = $+{Distribution};
+            my $kvpairs = $+{kvpairs};
+
+            unless ($expect eq 'first heading'
+                || $expect eq 'next heading or eof') {
+                $entry->ERROR(
+                    [
+                        $position,
+                        "found start of entry where expected $expect",$line
+                    ]
+                );
+                push @{$self->errors}, $entry->ERROR;
+            }
+
+            unless ($entry->is_empty) {
+                $entry->Closes(find_closes($entry->Changes));
+
+                push @{$self->entries}, $entry;
+                $entry = Lintian::Changelog::Entry->new;
+            }
+
+            $entry->position($position);
+
+            $entry->Header($line);
+
+            $entry->Source($source);
+            $entry->Version($version);
+
+            $distribution =~ s/^\s+//;
+            $entry->Distribution($distribution);
+
+            my %kvdone;
+            for my $kv (split(/\s*,\s*/,$kvpairs)) {
+                $kv =~ m/^([-0-9a-z]+)\=\s*(.*\S)$/i
+                  ||push @{$self->errors},
+                  [$position,"bad key-value after ';': '$kv'"];
+                my $k = ucfirst $1;
+                my $v = $2;
+                $kvdone{$k}++
+                  && push @{$self->errors},
+                  [$position,"repeated key-value $k"];
+                if ($k eq 'Urgency') {
+                    $v =~ m/^([-0-9a-z]+)((\s+.*)?)$/i
+                      ||push @{$self->errors},
+                      [$position,"badly formatted urgency value $v"];
+                    $entry->Urgency($1);
+                    $entry->Urgency_LC(lc($1));
+                    $entry->Urgency_Comment($2);
+                } elsif ($k =~ m/^X[BCS]+-/i) {
+                    # Extensions - XB for putting in Binary,
+                    # XC for putting in Control, XS for putting in Source
+                    $entry->{$k}= $v;
+                } else {
+                    push @{$self->errors},
+                      [$position,
+                        "unknown key-value key $k - copying to XS-$k"];
+                    $entry->{ExtraFields}{"XS-$k"} = $v;
+                }
+            }
+            $expect= 'start of change data';
+            $blanklines = 0;
+
+        } elsif ($line =~ /^(?:;;\s*)?Local variables:/i) {
+            last; # skip Emacs variables at end of file
+
+        } elsif ($line =~ /^vim:/i) {
+            last; # skip vim variables at end of file
+
+        } elsif ($line =~ /^\$\w+:.*\$/) {
+            next; # skip stuff that look like a CVS keyword
+
+        } elsif ($line =~ /^\# /) {
+            next; # skip comments, even that's not supported
+
+        } elsif ($line =~ m{^/\*.*\*/}) {
+            next; # more comments
+
+        } elsif ($line
+            =~ m/^(?:\w+\s+\w+\s+\d{1,2} \d{1,2}:\d{1,2}:\d{1,2}\s+[\w\s]*\d{4})\s+(?:.*)\s+[<\(](?:.*)[\)>]/
+            || $line
+            =~ m/^(?:\w+\s+\w+\s+\d{1,2},?\s*\d{4})\s+(?:.*)\s+[<\(](?:.*)[\)>]/
+            || $line =~ m/^(?:\w[-+0-9a-z.]*) \((?:[^\(\) \t]+)\)\;?/i
+            || $line =~ m/^(?:[\w.+-]+)[- ]\S+ Debian \S+/i
+            || $line =~ m/^Changes from version (?:.*) to (?:.*):/i
+            || $line =~ m/^Changes for [\w.+-]+-[\w.+-]+:?$/i
+            || fc($line) eq fc('Old Changelog:')
+            || $line =~ m/^(?:\d+:)?\w[\w.+~-]*:?$/) {
+            # save entries on old changelog format verbatim
+            # we assume the rest of the file will be in old format once we
+            # hit it for the first time
+            last;
+
+        } elsif ($line =~ m/^\S/) {
+            push @{$self->errors},
+              [$position,'badly formatted heading line', $line];
+
+        } elsif ($line
+            =~ m/^ \-\- (?<name>.*) <(?<email>.*)>(?<sep>  ?)(?<date>(?:\w+\,\s*)?\d{1,2}\s+\w+\s+\d{4}\s+\d{1,2}:\d\d:\d\d\s+[-+]\d{4}(?:\s+\([^\\\(\)]\))?)$/
+        ) {
+
+            my $name = $+{name};
+            my $email = $+{email};
+            my $separator = $+{sep};
+            my $date = $+{date};
+
+            $expect eq 'more change data or trailer'
+              || push @{$self->errors},
+              [$position,"found trailer where expected $expect", $line];
+            if ($separator ne $SPACE . $SPACE) {
+                push @{$self->errors},
+                  [$position,'badly formatted trailer line', $line];
+            }
+            $entry->Trailer($line);
+            $entry->Maintainer("$name <$email>")
+              unless length $entry->Maintainer;
+
+            unless(length $entry->Date && defined $entry->Timestamp) {
+                $entry->Date($date);
+                $entry->Timestamp(str2time($date));
+                unless (defined $entry->Timestamp) {
+                    push @{$self->errors},
+                      [$position,"could not parse date $date"];
+                }
+            }
+            $expect = 'next heading or eof';
+
+        } elsif ($line =~ m/^ \-\-/) {
+            $entry->{ERROR}
+              = [$position, 'badly formatted trailer line', $line];
+            push @{$self->errors}, $entry->ERROR;
+            #	    $expect = 'next heading or eof'
+            #		if $expect eq 'more change data or trailer';
+
+        } elsif ($line =~ m/^\s{2,}(\S)/) {
+            $expect eq 'start of change data'
+              || $expect eq 'more change data or trailer'
+              || do {
+                push @{$self->errors},
+                  [$position,"found change data where expected $expect",$line];
+                if (($expect eq 'next heading or eof')
+                    && !$entry->is_empty) {
+                    # lets assume we have missed the actual header line
+                    $entry->Closes(find_closes($entry->Changes));
+
+                    push @{$self->entries}, $entry;
+
+                    $entry = Lintian::Changelog::Entry->new;
+                    $entry->Source($UNKNOWN);
+                    $entry->Distribution($UNKNOWN);
+                    $entry->Urgency($UNKNOWN);
+                    $entry->Urgency_LC($UNKNOWN);
+                    $entry->Version($UNKNOWN . (++$unknown_version_counter));
+                    $entry->Urgency_Comment($EMPTY);
+                    $entry->ERROR(
+                        [
+                            $position,
+                            "found change data where expected $expect",$line
+                        ]
+                    );
+                }
+              };
+            $entry->{'Changes'} .= (" \n" x $blanklines)." $line\n";
+            if (!$entry->{Items} || $1 eq $ASTERISK) {
+                $entry->{Items} ||= [];
+                push @{$entry->{Items}}, "$line\n";
+            } else {
+                $entry->{'Items'}[-1] .= (" \n" x $blanklines)." $line\n";
+            }
+            $blanklines = 0;
+            $expect = 'more change data or trailer';
+
+        } elsif ($line !~ m/\S/) {
+            next
+              if $expect eq 'start of change data'
+              || $expect eq 'next heading or eof';
+            $expect eq 'more change data or trailer'
+              || push @{$self->errors},
+              [$position,"found blank line where expected $expect"];
+            $blanklines++;
+
+        } else {
+            push @{$self->errors}, [$position, 'unrecognised line', $line];
+            (        $expect eq 'start of change data'
+                  || $expect eq 'more change data or trailer')
+              && do {
+                # lets assume change data if we expected it
+                $entry->{'Changes'} .= (" \n" x $blanklines)." $line\n";
+                if (!$entry->{Items}) {
+                    $entry->{Items} ||= [];
+                    push @{$entry->{Items}}, "$line\n";
+                } else {
+                    $entry->{'Items'}[-1] .= (" \n" x $blanklines)." $line\n";
+                }
+                $blanklines = 0;
+                $expect = 'more change data or trailer';
+                $entry->ERROR([$position, 'unrecognised line', $line]);
+              };
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    $expect eq 'next heading or eof'
+      || do {
+        $entry->ERROR([$position, "found eof where expected $expect"]);
+        push @{$self->errors}, $entry->ERROR;
+      };
+
+    unless ($entry->is_empty) {
+        $entry->Closes(find_closes($entry->Changes));
+        push @{$self->entries}, $entry;
+    }
+
+    return;
+}
+
+=item errors
+
+=item entries
+
+=cut
+
+has errors => (is => 'rw', default => sub { [] });
+has entries => (is => 'rw', default => sub { [] });
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Changelog/Entry.pm b/lib/Lintian/Changelog/Entry.pm
new file mode 100644
index 0000000..f36cb92
--- /dev/null
+++ b/lib/Lintian/Changelog/Entry.pm
@@ -0,0 +1,184 @@
+#
+# Lintian::Changelog::Entry
+#
+# Copyright (C) 2005 Frank Lichtenheld <frank@lichtenheld.de>
+# Copyright (C) 2019 Felix Lechner <felix.lechner@lease-up.com>
+#
+#    This program is free software; you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License as published by
+#    the Free Software Foundation; either version 2 of the License, or
+#    (at your option) any later version.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License
+#    along with this program; if not, write to the Free Software
+#    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+#
+
+package Lintian::Changelog::Entry;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+const my $EMPTY => q{};
+const my $UNKNOWN => q{unknown};
+
+has Changes => (is => 'rw', default => $EMPTY);
+has Closes => (is => 'rw');
+has Date => (is => 'rw');
+has Distribution => (is => 'rw');
+has Header => (is => 'rw');
+#has Items => (is => 'rw', default => sub { [] });
+has Maintainer => (is => 'rw');
+has Source => (is => 'rw');
+has Timestamp => (is => 'rw');
+has Trailer => (is => 'rw');
+has Urgency => (is => 'rw', default => $UNKNOWN);
+has Urgency_LC => (is => 'rw', default => $UNKNOWN);
+has Urgency_Comment => (is => 'rw', default => $EMPTY);
+has Version => (is => 'rw');
+has ERROR => (is => 'rw');
+has position => (is => 'rw');
+
+=head1 NAME
+
+Lintian::Changelog::Entry - represents one entry in a Debian changelog
+
+=head1 SYNOPSIS
+
+=head1 DESCRIPTION
+
+=head2 Methods
+
+=head3 init
+
+Creates a new object, no options.
+
+=head3 new
+
+Alias for init.
+
+=head3 is_empty
+
+Checks if the object is actually initialized with data. Due to limitations
+in Parse::DebianChangelog this currently simply checks if one of the
+fields Source, Version, Maintainer, Date, or Changes is initialized.
+
+=head2 Accessors
+
+The following fields are available via accessor functions (all
+fields are string values unless otherwise noted):
+
+=over 4
+
+=item Source
+
+=item Version
+
+=item Distribution
+
+=item Urgency
+
+=item Urgency_Comment
+
+=item C<Urgency_LC>
+
+=item C<ExtraFields>
+
+Extra_Fields (all fields except for urgency as hash; POD spelling forces the underscore)
+
+=item Header
+
+Header (the whole header in verbatim form)
+
+=item Changes
+
+Changes (the actual content of the bug report, in verbatim form)
+
+=item Trailer
+
+Trailer (the whole trailer in verbatim form)
+
+=item Closes
+
+Closes (Array of bug numbers)
+
+=item Maintainer
+
+=item C<MaintainerEmail>
+
+=item Date
+
+=item Timestamp
+
+Timestamp (Date expressed in seconds since the epoch)
+
+=item ERROR
+
+Last parse error related to this entry in the format described
+at Parse::DebianChangelog::get_parse_errors.
+
+=item position
+
+=back
+
+=begin Pod::Coverage
+
+Changes
+Closes
+Date
+Distribution
+Header
+Maintainer
+C<MaintainerEmail>
+Source
+Timestamp
+Trailer
+
+=end Pod::Coverage
+
+=cut
+
+sub is_empty {
+    my ($self) = @_;
+
+    return !(length $self->Changes
+        || length $self->Source
+        || length $self->Version
+        || length $self->Maintainer
+        || length $self->Date);
+}
+
+1;
+__END__
+
+=head1 SEE ALSO
+
+Originally based on Parse::DebianChangelog by Frank Lichtenheld, E<lt>frank@lichtenheld.deE<gt>
+
+=head1 AUTHOR
+
+Written by Felix Lechner <felix.lechner@lease-up.com> for Lintian in response to #933134.
+
+=head1 COPYRIGHT AND LICENSE
+
+Please see in the code; FSF's standard short text triggered a POD spelling error
+here.
+
+=cut
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Changelog/Version.pm b/lib/Lintian/Changelog/Version.pm
new file mode 100644
index 0000000..d0e29f4
--- /dev/null
+++ b/lib/Lintian/Changelog/Version.pm
@@ -0,0 +1,250 @@
+# Copyright (C) 2019 Felix Lechner <felix.lechner@lease-up.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Changelog::Version;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp;
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+const my $EMPTY => q{};
+
+=head1 NAME
+
+Lintian::Changelog::Version -- Parse a literal version string into its constituents
+
+=head1 SYNOPSIS
+
+ use Lintian::Changelog::Version;
+
+ my $version = Lintian::Changelog::Version->new;
+ $version->assign('1.2.3-4', undef);
+
+=head1 DESCRIPTION
+
+A class for parsing literal version strings
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item new ()
+
+Creates a new Lintian::Changelog::Version object.
+
+=cut
+
+=back
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item assign (LITERAL, NATIVE)
+
+Assign the various members in the Lintian::Changelog::Version object
+using the LITERAL version string and the NATIVE boolean selector.
+
+=cut
+
+sub assign {
+
+    my ($self, $literal, $native) = @_;
+
+    croak encode_utf8('Literal version string required for version parsing')
+      unless defined $literal;
+
+    croak encode_utf8('Native flag required for version parsing')
+      unless defined $native;
+
+    my $epoch_pattern      = qr/([0-9]+)/;
+    my $upstream_pattern   = qr/([A-Za-z0-9.+\-~]+?)/;
+    my $maintainer_revision_pattern     = qr/([A-Za-z0-9.+~]+?)/;
+    my $source_nmu_pattern = qr/([A-Za-z0-9.+~]+)/;
+    my $bin_nmu_pattern    = qr/([0-9]+)/;
+
+    my $source_pattern;
+
+    # these capture three matches each
+    $source_pattern
+      = qr/$upstream_pattern/
+      . qr/(?:-$maintainer_revision_pattern(?:\.$source_nmu_pattern)?)?/
+      if !$native;
+    $source_pattern
+      = qr/()/
+      . qr/$maintainer_revision_pattern/
+      . qr/(?:\+nmu$source_nmu_pattern)?/
+      if $native;
+
+    my $pattern
+      = qr/^/
+      . qr/(?:$epoch_pattern:)?/
+      . qr/$source_pattern/
+      . qr/(?:\+b$bin_nmu_pattern)?/. qr/$/;
+
+    my ($epoch, $upstream, $maintainer_revision, $source_nmu, $binary_nmu)
+      = ($literal =~ $pattern);
+
+    $epoch //= $EMPTY;
+    $upstream //= $EMPTY;
+    $maintainer_revision //= $EMPTY;
+    $source_nmu //= $EMPTY;
+    $binary_nmu //= $EMPTY;
+
+    my $source_nmu_string = $EMPTY;
+
+    $source_nmu_string = ($native ? "+nmu$source_nmu" : ".$source_nmu")
+      if length $source_nmu;
+
+    my $debian_source = $maintainer_revision . $source_nmu_string;
+
+    my $debian_no_epoch
+      = $debian_source . (length $binary_nmu ? "+b$binary_nmu" : $EMPTY);
+
+    my $upstream_string = (length $upstream ? "$upstream-" : $EMPTY);
+
+    my $no_epoch= $upstream_string . $debian_no_epoch;
+
+    my $epoch_string = (length $epoch ? "$epoch:" : $EMPTY);
+
+    my $reconstructed= $epoch_string . $no_epoch;
+
+    croak encode_utf8(
+        "Failed to parse package version: $reconstructed ne $literal")
+      unless $reconstructed eq $literal;
+
+    $self->literal($literal);
+    $self->epoch($epoch);
+    $self->no_epoch($no_epoch);
+    $self->upstream($upstream);
+    $self->maintainer_revision($maintainer_revision);
+    $self->debian_source($debian_source);
+    $self->debian_no_epoch($debian_no_epoch);
+    $self->source_nmu($source_nmu);
+    $self->binary_nmu($binary_nmu);
+
+    my $without_source_nmu
+      = $epoch_string . $upstream_string . $maintainer_revision;
+
+    $self->without_source_nmu($without_source_nmu);
+
+    my $backport_pattern = qr/^(.*)[+~]deb(\d+)u(\d+)$/;
+
+    my ($debian_without_backport, $backport_release, $backport_revision)
+      = ($self->maintainer_revision =~ $backport_pattern);
+
+    $debian_without_backport //= $maintainer_revision;
+    $backport_release //= $EMPTY;
+    $backport_revision //= $EMPTY;
+
+    $self->debian_without_backport($debian_without_backport);
+    $self->backport_release($backport_release);
+    $self->backport_revision($backport_revision);
+
+    my $without_backport
+      = $epoch_string . $upstream_string . $debian_without_backport;
+
+    $self->without_backport($without_backport);
+
+    return;
+}
+
+=item literal
+
+=item epoch
+
+=item no_epoch
+
+=item upstream
+
+=item maintainer_revision
+
+=item debian_source
+
+=item debian_no_epoch
+
+=item source_nmu
+
+=item binary_nmu
+
+=item without_source_nmu
+
+=item debian_without_backport
+
+=item backport_release
+
+=item backport_revision
+
+=item without_backport
+
+=cut
+
+has literal => (is => 'rw', default => $EMPTY);
+
+has epoch => (is => 'rw', default => $EMPTY);
+
+has no_epoch => (is => 'rw', default => $EMPTY);
+
+has upstream => (is => 'rw', default => $EMPTY);
+
+has maintainer_revision => (is => 'rw', default => $EMPTY);
+
+has debian_source => (is => 'rw', default => $EMPTY);
+
+has debian_no_epoch => (is => 'rw', default => $EMPTY);
+
+has source_nmu => (is => 'rw', default => $EMPTY);
+
+has binary_nmu => (is => 'rw', default => $EMPTY);
+
+has without_source_nmu => (is => 'rw', default => $EMPTY);
+
+has debian_without_backport => (is => 'rw', default => $EMPTY);
+
+has backport_release => (is => 'rw', default => $EMPTY);
+
+has backport_revision => (is => 'rw', default => $EMPTY);
+
+has without_backport => (is => 'rw', default => $EMPTY);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check.pm b/lib/Lintian/Check.pm
new file mode 100644
index 0000000..02e459f
--- /dev/null
+++ b/lib/Lintian/Check.pm
@@ -0,0 +1,232 @@
+# Copyright (C) 2012 Niels Thykier <niels@thykier.net>
+# Copyright (C) 2017-2018 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2019-2021 Felix Lechner <felix.lechner@lease-up.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Hint::Annotated;
+use Lintian::Hint::Pointed;
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $UNDERSCORE => q{_};
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Check -- Common facilities for Lintian checks
+
+=head1 SYNOPSIS
+
+ use Moo;
+ use namespace::clean;
+
+ with('Lintian::Check');
+
+=head1 DESCRIPTION
+
+A class for operating Lintian checks
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item name
+
+=item processable
+
+=item group
+
+=item profile
+
+=item hints
+
+=cut
+
+has name => (is => 'rw', default => $EMPTY);
+has processable => (is => 'rw', default => sub { {} });
+has group => (is => 'rw', default => sub { {} });
+has profile => (is => 'rw');
+
+has hints => (is => 'rw', default => sub { [] });
+
+=item data
+
+=cut
+
+sub data {
+    my ($self) = @_;
+
+    return $self->profile->data;
+}
+
+=item visit_files
+
+=cut
+
+sub visit_files {
+    my ($self, $index) = @_;
+
+    my $visit_hook = 'visit' . $UNDERSCORE . $index . $UNDERSCORE . 'files';
+
+    return
+      unless $self->can($visit_hook);
+
+    my @items = @{$self->processable->$index->sorted_list};
+
+    # do not look inside quilt directory
+    @items = grep { $_->name !~ m{^\.pc/} } @items
+      if $index eq 'patched';
+
+    # exclude Lintian's test suite from source scans
+    @items = grep { $_->name !~ m{^t/} } @items
+      if $self->processable->name eq 'lintian' && $index eq 'patched';
+
+    $self->$visit_hook($_) for @items;
+
+    return;
+}
+
+=item run
+
+=cut
+
+sub run {
+    my ($self) = @_;
+
+    # do not carry over any hints
+    $self->hints([]);
+
+    my $type = $self->processable->type;
+
+    if ($type eq 'source') {
+
+        $self->visit_files('orig');
+        $self->visit_files('patched');
+    }
+
+    if ($type eq 'binary' || $type eq 'udeb') {
+
+        $self->visit_files('control');
+        $self->visit_files('installed');
+
+        $self->installable
+          if $self->can('installable');
+    }
+
+    $self->$type
+      if $self->can($type);
+
+    $self->always
+      if $self->can('always');
+
+    return @{$self->hints};
+}
+
+=item pointed_hint
+
+=cut
+
+sub pointed_hint {
+    my ($self, $tag_name, $pointer, @notes) = @_;
+
+    my $hint = Lintian::Hint::Pointed->new;
+
+    $hint->tag_name($tag_name);
+    $hint->issued_by($self->name);
+
+    my $note = stringify(@notes);
+    $hint->note($note);
+    $hint->pointer($pointer);
+
+    push(@{$self->hints}, $hint);
+
+    return;
+}
+
+=item hint
+
+=cut
+
+sub hint {
+    my ($self, $tag_name, @notes) = @_;
+
+    my $hint = Lintian::Hint::Annotated->new;
+
+    $hint->tag_name($tag_name);
+    $hint->issued_by($self->name);
+
+    my $note = stringify(@notes);
+    $hint->note($note);
+
+    push(@{$self->hints}, $hint);
+
+    return;
+}
+
+=item stringify
+
+=cut
+
+sub stringify {
+    my (@arguments) = @_;
+
+    # skip empty arguments
+    my @meaningful = grep { length } @arguments;
+
+    # trim both ends of each item
+    s{^ \s+ | \s+ $}{}gx for @meaningful;
+
+    # concatenate with spaces
+    my $text = join($SPACE, @meaningful) // $EMPTY;
+
+    # escape newlines; maybe add others
+    $text =~ s{\n}{\\n}g;
+
+    return $text;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Apache2.pm b/lib/Lintian/Check/Apache2.pm
new file mode 100644
index 0000000..b8dde2d
--- /dev/null
+++ b/lib/Lintian/Check/Apache2.pm
@@ -0,0 +1,337 @@
+# apache2 -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2012 Arno Toell
+# Copyright (C) 2017-2018 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Apache2;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use File::Basename;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Relation;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# whether the package appears to be an Apache2 module/web application
+has is_apache2_related => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        for my $item (@{$self->processable->installed->sorted_list}) {
+
+            return 1
+              if $item->name =~ m{^ usr/lib/apache2/modules/ }x
+              && $item->basename =~ m{ [.]so $}x;
+
+            return 1
+              if $item->name
+              =~ m{^ etc/apache2/ (?:conf|site) - (?:available|enabled) / }x;
+
+            return 1
+              if $item->name =~ m{^ etc/apache2/conf[.]d/}x;
+        }
+
+        return 0;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # Do nothing if the package in question appears to be related to
+    # the web server itself
+    return
+      if $self->processable->name =~ m/^apache2(:?\.2)?(?:-\w+)?$/;
+
+    # File is probably not relevant to us, ignore it
+    return
+      if $item->is_dir;
+
+    return
+      if $item->name !~ m{^(?:usr/lib/apache2/modules/|etc/apache2/)};
+
+    # Package installs an unrecognized file - check this for all files
+    if (   $item->name !~ /\.conf$/
+        && $item->name =~ m{^etc/apache2/(conf|site|mods)-available/(.*)$}){
+
+        my $temp_type = $1;
+        my $temp_file = $2;
+
+        # ... except modules which are allowed to ship .load files
+        $self->pointed_hint('apache2-configuration-files-need-conf-suffix',
+            $item->pointer)
+          unless $temp_type eq 'mods' && $temp_file =~ /\.load$/;
+    }
+
+    # Package appears to be a binary module
+    if ($item->name =~ m{^usr/lib/apache2/modules/(.*)\.so$}) {
+
+        $self->check_module_package($item, $1);
+    }
+
+    # Package appears to be a web application
+    elsif ($item->name =~ m{^etc/apache2/(conf|site)-available/(.*)$}) {
+
+        $self->check_web_application_package($item, $1, $2);
+    }
+
+    # Package appears to be a legacy web application
+    elsif ($item->name =~ m{^etc/apache2/conf\.d/(.*)$}) {
+
+        $self->pointed_hint(
+            'apache2-reverse-dependency-uses-obsolete-directory',
+            $item->pointer);
+        $self->check_web_application_package($item,'conf', $1);
+    }
+
+    # Package does scary things
+    elsif ($item->name =~ m{^etc/apache2/(?:conf|sites|mods)-enabled/.*$}) {
+
+        $self->pointed_hint(
+            'apache2-reverse-dependency-ships-file-in-not-allowed-directory',
+            $item->pointer);
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    # Do nothing if the package in question appears to be related to
+    # the web server itself
+    return
+      if $self->processable->name =~ m/^apache2(:?\.2)?(?:-\w+)?$/;
+
+    return;
+}
+
+sub check_web_application_package {
+    my ($self, $item, $pkgtype, $webapp) = @_;
+
+    my $pkg = $self->processable->name;
+    my $processable = $self->processable;
+
+    $self->pointed_hint('non-standard-apache2-configuration-name',
+        $item->pointer, "$webapp != $pkg.conf")
+      if $webapp ne "$pkg.conf"
+      || $webapp =~ /^local-/;
+
+    my $rel = $processable->relation('strong')
+      ->logical_and($processable->relation('Recommends'));
+
+    # A web application must not depend on apache2-whatever
+    my $visit = sub {
+        if (m/^apache2(?:\.2)?-(?:common|data|bin)$/) {
+            $self->pointed_hint(
+                'web-application-depends-on-apache2-data-package',
+                $item->pointer, $_, $webapp);
+            return 1;
+        }
+        return 0;
+    };
+    $rel->visit($visit, Lintian::Relation::VISIT_STOP_FIRST_MATCH);
+
+    # ... nor on apache2 only. Moreover, it should be in the form
+    # apache2 | httpd but don't worry about versions, virtual package
+    # don't support that
+    $self->pointed_hint('web-application-works-only-with-apache',
+        $item->pointer, $webapp)
+      if $rel->satisfies('apache2');
+
+    $self->inspect_conf_file($pkgtype, $item);
+    return;
+}
+
+sub check_module_package {
+    my ($self, $item, $module) = @_;
+
+    my $pkg = $self->processable->name;
+    my $processable = $self->processable;
+
+    # We want packages to be follow our naming scheme. Modules should be named
+    # libapache2-mod-<foo> if it ships a mod_foo.so
+    # NB: Some modules have uppercase letters in them (e.g. Ruwsgi), but
+    # obviously the package should be in all lowercase.
+    my $expected_name = 'libapache2-' . lc($module);
+
+    my $rel;
+
+    $expected_name =~ tr/_/-/;
+    $self->pointed_hint('non-standard-apache2-module-package-name',
+        $item->pointer, "$pkg != $expected_name")
+      if $expected_name ne $pkg;
+
+    $rel = $processable->relation('strong')
+      ->logical_and($processable->relation('Recommends'));
+
+    $self->pointed_hint('apache2-module-does-not-depend-on-apache2-api',
+        $item->pointer)
+      if !$rel->matches(qr/^apache2-api-\d+$/);
+
+    # The module is called mod_foo.so, thus the load file is expected to be
+    # named foo.load
+    my $load_file = $module;
+    my $conf_file = $module;
+    $load_file =~ s{^mod.(.*)$}{etc/apache2/mods-available/$1.load};
+    $conf_file =~ s{^mod.(.*)$}{etc/apache2/mods-available/$1.conf};
+
+    if (my $f = $processable->installed->lookup($load_file)) {
+        $self->inspect_conf_file('mods', $f);
+    } else {
+        $self->pointed_hint('apache2-module-does-not-ship-load-file',
+            $item->pointer, $load_file);
+    }
+
+    if (my $f = $processable->installed->lookup($conf_file)) {
+        $self->inspect_conf_file('mods', $f);
+    }
+
+    return;
+}
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $self->is_apache2_related;
+
+    return
+      unless $item->is_maintainer_script;
+
+    # skip anything but shell scripts
+    return
+      unless $item->is_shell_script;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $sfd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$sfd>) {
+
+        # skip comments
+        next
+          if $line =~ /^ [#]/x;
+
+        # Do not allow reverse dependencies to call "a2enmod" and friends
+        # directly
+        if ($line =~ m{ \b (a2(?:en|dis)(?:conf|site|mod)) \b }x) {
+
+            my $command = $1;
+
+            $self->pointed_hint(
+                'apache2-reverse-dependency-calls-wrapper-script',
+                $item->pointer($position), $command);
+        }
+
+        # Do not allow reverse dependencies to call "invoke-rc.d apache2
+        $self->pointed_hint('apache2-reverse-dependency-calls-invoke-rc.d',
+            $item->pointer($position))
+          if $line =~ /invoke-rc\.d\s+apache2/;
+
+        # XXX: Check whether apache2-maintscript-helper is used
+        # unconditionally e.g. not protected by a [ -e ], [ -x ] or so.
+        # That's going to be complicated. Or not possible without grammar
+        # parser.
+
+    } continue {
+        ++$position;
+    }
+
+    return;
+}
+
+sub inspect_conf_file {
+    my ($self, $conftype, $item) = @_;
+
+    # Don't follow unsafe links
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $skip = 0;
+
+    my $position = 1;
+    while (my $line = <$fd>)  {
+
+        ++$skip
+          if $line =~ m{<\s*IfModule.*!\s*mod_authz_core}
+          || $line =~ m{<\s*IfVersion\s+<\s*2\.3};
+
+        for my $directive ('Order', 'Satisfy', 'Allow', 'Deny',
+            qr{</?Limit.*?>}xsm, qr{</?LimitExcept.*?>}xsm) {
+
+            if ($line =~ m{\A \s* ($directive) (?:\s+|\Z)}xsm && !$skip) {
+
+                $self->pointed_hint('apache2-deprecated-auth-config',
+                    $item->pointer($position), $1);
+            }
+        }
+
+        if ($line =~ /^#\s*(Depends|Conflicts):\s+(.*?)\s*$/) {
+            my ($field, $value) = ($1, $2);
+
+            $self->pointed_hint('apache2-unsupported-dependency',
+                $item->pointer($position), $field)
+              if $field eq 'Conflicts' && $conftype ne 'mods';
+
+            my @dependencies = split(/[\n\s]+/, $value);
+            for my $dep (@dependencies) {
+
+                $self->pointed_hint('apache2-unparsable-dependency',
+                    $item->pointer($position), $dep)
+                  if $dep =~ /[^\w\.]/
+                  || $dep =~ /^mod\_/
+                  || $dep =~ /\.(?:conf|load)/;
+            }
+        }
+
+        --$skip
+          if $line =~ m{<\s*/\s*If(Module|Version)};
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/ApplicationNotLibrary.pm b/lib/Lintian/Check/ApplicationNotLibrary.pm
new file mode 100644
index 0000000..a598385
--- /dev/null
+++ b/lib/Lintian/Check/ApplicationNotLibrary.pm
@@ -0,0 +1,141 @@
+# application-not-library -- find applications packaged like a library -*- perl -*-
+#
+# Copyright (C) 2014-2015 Axel Beckert <abe@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::ApplicationNotLibrary;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(any);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub installable {
+    my ($self) = @_;
+
+    # big exception list for all tags
+    return
+      # perl itself
+      if $self->processable->name =~ /^perl(?:-base)?$/
+      # ruby itself
+      || $self->processable->name =~ /^ruby[\d.]*$/
+      # python itself
+      || $self->processable->name =~ /^python[\d.]*(?:-dev|-minimal)?$/
+      # cpan related tools
+      || $self->processable->name =~ /^cpan/
+      # perl module tools
+      || $self->processable->name =~ /^libmodule-.*-perl$/
+      # perl debugging tools
+      || $self->processable->name =~ /^libdevel-.*-perl$/
+      # perl-handling tools
+      || $self->processable->name =~ /^libperl.*-perl$/
+      # perl testing tools
+      || $self->processable->name =~ /^libtest-.*-perl$/
+      # python packaging stuff
+      || $self->processable->name =~ /^python[\d.]*-(?:stdeb|setuptools)$/
+      # ruby packaging stuff
+      || $self->processable->name =~ /^gem2deb/
+      # rendering engine
+      || $self->processable->name =~ /^xulrunner/
+      # generic helpers
+      || $self->processable->name =~ /^lib.*-(?:utils|tools|bin|dev)/
+      # whitelist
+      || (
+        any { $self->processable->name eq $_ }
+        qw(
+
+        rake
+        bundler
+        coderay
+        kdelibs-bin
+        libapp-options-perl
+
+        )
+      );
+
+    my @programs;
+    for my $searched_folder (qw{bin sbin usr/bin usr/sbin usr/games}) {
+
+        my $directory_item
+          = $self->processable->installed->lookup("$searched_folder/");
+        next
+          unless defined $directory_item;
+
+        for my $program_item ($directory_item->children) {
+
+            # ignore debhelper plugins
+            next
+              if $program_item->basename =~ /^dh_/;
+
+            # ignore library configuration tools
+            next
+              if $program_item->name =~ /properties$/;
+
+            # ignore library maintenance tools
+            next
+              if $program_item->name  =~ /update$/;
+
+            push(@programs, $program_item);
+        }
+    }
+
+    return
+      unless @programs;
+
+    # check for library style package names
+    if (   $self->processable->name =~ m{^ lib (?:.+) -perl $}x
+        || $self->processable->name =~ m{^ruby-}x
+        || $self->processable->name =~ m{^python[\d.]*-}x) {
+
+        if ($self->processable->name =~ m{^ libapp (?:.+) -perl $}x) {
+            $self->pointed_hint('libapp-perl-package-name', $_->pointer)
+              for @programs;
+
+        } else {
+            $self->pointed_hint('library-package-name-for-application',
+                $_->pointer)
+              for @programs;
+        }
+    }
+
+    my $section = $self->processable->fields->value('Section');
+
+    # oldlibs is ok
+    if ($section =~ m{ perl | python | ruby | (?: ^ | / ) libs }x) {
+
+        $self->pointed_hint('application-in-library-section',
+            $_->pointer, $section)
+          for @programs;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/AppstreamMetadata.pm b/lib/Lintian/Check/AppstreamMetadata.pm
new file mode 100644
index 0000000..97a57d4
--- /dev/null
+++ b/lib/Lintian/Check/AppstreamMetadata.pm
@@ -0,0 +1,269 @@
+# appstream-metadata -- lintian check script -*- perl -*-
+
+# Copyright (C) 2016 Petter Reinholdtsen
+# Copyright (C) 2017-2018 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::AppstreamMetadata;
+
+# For .desktop files, the lintian check would be really easy: Check if
+# .desktop file is there, check if matching file exists in
+# /usr/share/metainfo, if not throw a warning. Maybe while we're at it
+# also check for legacy locations (stuff in /usr/share/appdata) and
+# legacy data (metainfo files starting with `<application>`).
+#
+# For modaliases, maybe udev rules could give some hints.
+# Check modalias values to ensure hex numbers are using capital A-F.
+
+use v5.20;
+use warnings;
+use utf8;
+use autodie qw(open);
+
+use File::Basename qw(basename);
+use Syntax::Keyword::Try;
+use XML::LibXML;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub installable {
+    my ($self) = @_;
+
+    my $pkg = $self->processable->name;
+    my $type = $self->processable->type;
+    my $processable = $self->processable;
+    my $group = $self->group;
+
+    my (%desktopfiles, %metainfo, @udevrules);
+    my $found_modalias = 0;
+    my $modaliases = [];
+    if (
+        defined(
+            my $dir
+              = $processable->installed->resolve_path(
+                'usr/share/applications/')
+        )
+    ) {
+        for my $item ($dir->descendants) {
+            $desktopfiles{$item} = 1 if ($item->is_file);
+        }
+    }
+    if (
+        defined(
+            my $dir
+              = $processable->installed->resolve_path('usr/share/metainfo/')
+        )
+    ) {
+        for my $item ($dir->children) {
+            if ($item->is_file) {
+                $metainfo{$item} = 1;
+                $found_modalias|= $self->check_modalias($item, $modaliases);
+            }
+        }
+    }
+    if (
+        defined(
+            my $dir
+              = $processable->installed->resolve_path('usr/share/appdata/')
+        )
+    ) {
+        for my $item ($dir->descendants) {
+            if ($item->is_file) {
+
+                $self->pointed_hint('appstream-metadata-in-legacy-location',
+                    $item->pointer);
+                $found_modalias|= $self->check_modalias($item, $modaliases);
+            }
+        }
+    }
+    foreach my $lib_dir (qw(usr/lib lib)) {
+        if (
+            defined(
+                my $dir = $processable->installed->resolve_path(
+                    "$lib_dir/udev/rules.d/")
+            )
+        ) {
+            for my $item ($dir->descendants) {
+                push(@udevrules, $item) if ($item->is_file);
+            }
+        }
+    }
+
+    for my $udevrule (@udevrules) {
+        if ($self->check_udev_rules($udevrule, $modaliases)
+            && !$found_modalias) {
+
+            $self->hint('appstream-metadata-missing-modalias-provide',
+                $udevrule);
+        }
+    }
+    return;
+}
+
+sub check_modalias {
+    my ($self, $item, $modaliases) = @_;
+
+    if (!$item->is_open_ok) {
+        # FIXME report this as an error
+        return 0;
+    }
+
+    my $parser = XML::LibXML->new;
+    $parser->set_option('no_network', 1);
+
+    my $doc;
+    try {
+        $doc = $parser->parse_file($item->unpacked_path);
+
+    } catch {
+
+        $self->pointed_hint('appstream-metadata-invalid',$item->pointer);
+
+        return 0;
+    }
+
+    return 0
+      unless $doc;
+
+    if ($doc->findnodes('/application')) {
+
+        $self->pointed_hint('appstream-metadata-legacy-format',$item->pointer);
+        return 0;
+    }
+
+    my @provides = $doc->findnodes('/component/provides');
+    return 0
+      unless @provides;
+
+    # take first one
+    my $first = $provides[0];
+    return 0
+      unless $first;
+
+    my @nodes = $first->getChildrenByTagName('modalias');
+    return 0
+      unless @nodes;
+
+    for my $node (@nodes) {
+
+        my $alias = $node->firstChild->data;
+        next
+          unless $alias;
+
+        push(@{$modaliases}, $alias);
+
+        $self->pointed_hint('appstream-metadata-malformed-modalias-provide',
+            $item->pointer,
+            "include non-valid hex digit in USB matching rule '$alias'")
+          if $alias =~ /^usb:v[0-9a-f]{4}p[0-9a-f]{4}d/i
+          && $alias !~ /^usb:v[0-9A-F]{4}p[0-9A-F]{4}d/;
+    }
+
+    return 1;
+}
+
+sub provides_user_device {
+    my ($self, $item, $position, $rule, $data) = @_;
+
+    my $retval = 0;
+
+    if (   $rule =~ /plugdev/
+        || $rule =~ /uaccess/
+        || $rule =~ /MODE=\"0666\"/) {
+
+        $retval = 1;
+    }
+
+    if ($rule =~ m/SUBSYSTEM=="usb"/) {
+        my ($vmatch, $pmatch);
+        if ($rule =~ m/ATTR\{idVendor\}=="([0-9a-fA-F]{4})"/) {
+            $vmatch = 'v' . uc($1);
+        }
+
+        if ($rule =~ m/ATTR\{idProduct\}=="([0-9a-fA-F]{4})"/) {
+            $pmatch = 'p' . uc($1);
+        }
+
+        if (defined $vmatch && defined $pmatch) {
+            my $match = "usb:${vmatch}${pmatch}d";
+            my $foundmatch;
+            for my $aliasmatch (@{$data}) {
+                if (0 == index($aliasmatch, $match)) {
+                    $foundmatch = 1;
+                }
+            }
+
+            $self->pointed_hint(
+                'appstream-metadata-missing-modalias-provide',
+                $item->pointer($position),
+                "match rule $match*"
+            ) unless $foundmatch;
+        }
+    }
+
+    return $retval;
+}
+
+sub check_udev_rules {
+    my ($self, $item, $data) = @_;
+
+    open(my $fd, '<', $item->unpacked_path);
+
+    my $cont;
+    my $retval = 0;
+
+    my $position = 0;
+    while (my $line = <$fd>) {
+
+        chomp $line;
+
+        if (defined $cont) {
+            $line = $cont . $line;
+            $cont = undef;
+        }
+
+        if ($line =~ /^(.*)\\$/) {
+            $cont = $1;
+            next;
+        }
+
+        # skip comments
+        next
+          if $line =~ /^#.*/;
+
+        $retval |= $self->provides_user_device($item, $position, $line, $data);
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return $retval;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Apt.pm b/lib/Lintian/Check/Apt.pm
new file mode 100644
index 0000000..08b5ce6
--- /dev/null
+++ b/lib/Lintian/Check/Apt.pm
@@ -0,0 +1,69 @@
+# apt -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Apt;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      if $self->processable->source_name eq 'apt';
+
+    # /etc/apt/preferences
+    $self->pointed_hint('package-installs-apt-preferences', $item->pointer)
+      if $item->name =~ m{^ etc/apt/preferences (?: $ | [.]d / [^/]+ ) }x;
+
+    # /etc/apt/sources
+    unless ($self->processable->name =~ m{ -apt-source $}x) {
+
+        $self->pointed_hint('package-installs-apt-sources', $item->pointer)
+          if $item->name
+          =~ m{^ etc/apt/sources[.]list (?: $ | [.]d / [^/]+ ) }x;
+    }
+
+    # /etc/apt/trusted.gpg
+    unless (
+        $self->processable->name=~ m{ (?: -apt-source | -archive-keyring ) $}x)
+    {
+
+        $self->pointed_hint('package-installs-apt-keyring', $item->pointer)
+          if $item->name=~ m{^ etc/apt/trusted[.]gpg (?: $ | [.]d / [^/]+ ) }x;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Archive/File/Name/Length.pm b/lib/Lintian/Check/Archive/File/Name/Length.pm
new file mode 100644
index 0000000..212a6b9
--- /dev/null
+++ b/lib/Lintian/Check/Archive/File/Name/Length.pm
@@ -0,0 +1,93 @@
+# archive/file/name/length -- lintian check script -*- perl -*-
+
+# Copyright (C) 2011 Niels Thykier <niels@thykier.net>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Archive::File::Name::Length;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use File::Basename;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SPACE => q{ };
+
+const my $FILENAME_LENGTH_LIMIT => 80;
+
+# We could derive this from data/fields/architectures, but that
+# contains things like kopensolaris-sparc64 and kfreebsd-sparc64,
+# neither of which Debian officially supports.
+const my $LONGEST_ARCHITECTURE => length 'kfreebsd-amd64';
+
+sub always {
+    my ($self) = @_;
+
+    # Skip auto-generated packages (dbgsym)
+    return
+      if $self->processable->fields->declares('Auto-Built-Package');
+
+    my $basename = basename($self->processable->path);
+    # remove salsaci suffix
+    my $nosalsabasename = $basename;
+    $nosalsabasename
+      =~ s/[+]salsaci[+]\d+[+]\d+(_[[:alnum:]]+\.[[:alnum:]]+)$/$1/;
+
+    my $adjusted_length
+      = length($nosalsabasename)
+      - length($self->processable->architecture)
+      + $LONGEST_ARCHITECTURE;
+
+    $self->hint('package-has-long-file-name', $basename)
+      if $adjusted_length > $FILENAME_LENGTH_LIMIT;
+
+    return;
+}
+
+sub source {
+    my ($self) = @_;
+
+    my @lines = $self->processable->fields->trimmed_list('Files', qr/\n/);
+
+    for my $line (@lines) {
+
+        my (undef, undef, $name) = split($SPACE, $line);
+        next
+          unless length $name;
+
+        $self->hint('source-package-component-has-long-file-name', $name)
+          if length $name > $FILENAME_LENGTH_LIMIT;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Archive/Liberty/Mismatch.pm b/lib/Lintian/Check/Archive/Liberty/Mismatch.pm
new file mode 100644
index 0000000..6d050f6
--- /dev/null
+++ b/lib/Lintian/Check/Archive/Liberty/Mismatch.pm
@@ -0,0 +1,138 @@
+# archive/liberty/mismatch -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Archive::Liberty::Mismatch;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(all none);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $ARROW => q{->};
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+    my $source_fields = $control->source_fields;
+
+    # Check that every package is in the same archive area, except
+    # that sources in main can deliver both main and contrib packages.
+    # The source package may or may not have a section specified; if
+    # it doesn't, derive the expected archive area from the first
+    # binary package by leaving $source_liberty undefined until parsing the
+    # first binary section.  Missing sections will be caught by other
+    # checks.
+
+    my $source_section = $source_fields->value('Section');
+    return
+      unless length $source_section;
+
+    # see policy 2.4
+    $source_section = "main/$source_section"
+      if $source_section !~ m{/};
+
+    my $source_liberty = $source_section;
+    $source_liberty =~ s{ / .* $}{}x;
+
+    my %liberty_by_installable;
+
+    for my $installable ($control->installables) {
+
+        my $installable_fields = $control->installable_fields($installable);
+
+        my $installable_section;
+        if ($installable_fields->declares('Section')) {
+
+            $installable_section = $installable_fields->value('Section');
+
+            # see policy 2.4
+            $installable_section = "main/$installable_section"
+              if $installable_section !~ m{/};
+        }
+
+        $installable_section ||= $source_section;
+
+        my $installable_liberty = $installable_section;
+        $installable_liberty =~ s{ / .* $}{}x;
+
+        $liberty_by_installable{$installable} = $installable_liberty;
+
+        # special exception for contrib built from main
+        next
+          if $source_liberty eq 'main' && $installable_liberty eq 'contrib';
+
+        # and non-free-firmware built from non-free
+        next
+          if $source_liberty eq 'non-free'
+          && $installable_liberty eq 'non-free-firmware';
+        my $control_item= $self->processable->debian_control->item;
+        my $position = $installable_fields->position('Section');
+        my $pointer = $control_item->pointer($position);
+
+        $self->pointed_hint('archive-liberty-mismatch', $pointer,
+            "(in section for $installable)",
+            $installable_liberty, 'vs', $source_liberty)
+          if $source_liberty ne $installable_liberty;
+    }
+
+    # in ascending order of liberty
+    for my $inferior_liberty ('non-free', 'contrib') {
+
+        # must remain inferior
+        last
+          if $inferior_liberty eq $source_liberty;
+
+        my $control_item= $self->processable->debian_control->item;
+        my $position = $source_fields->position('Section');
+        my $pointer = $control_item->pointer($position);
+
+        $self->pointed_hint('archive-liberty-mismatch', $pointer,
+            '(in source paragraph)',
+            $source_liberty,$ARROW, $inferior_liberty)
+          if (
+            all { $liberty_by_installable{$_} eq $inferior_liberty }
+            keys %liberty_by_installable
+          )
+          && (
+            none { $liberty_by_installable{$_} eq $source_liberty }
+            keys %liberty_by_installable
+          );
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Archive/NonFree/Autobuild.pm b/lib/Lintian/Check/Archive/NonFree/Autobuild.pm
new file mode 100644
index 0000000..939f0fc
--- /dev/null
+++ b/lib/Lintian/Check/Archive/NonFree/Autobuild.pm
@@ -0,0 +1,70 @@
+# archive/non-free/autobuild -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Archive::NonFree::Autobuild;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    return
+      unless $self->processable->is_non_free;
+
+    my $control = $self->processable->debian_control;
+    my $source_fields = $control->source_fields;
+
+    my $changes = $self->group->changes;
+
+    # source-only upload
+    if (defined $changes
+        && $changes->fields->value('Architecture') eq 'source') {
+
+        my $field = 'XS-Autobuild';
+
+        my $control_item= $self->processable->debian_control->item;
+        my $position = $source_fields->position($field);
+        my $pointer = $control_item->pointer($position);
+
+        $self->pointed_hint('source-only-upload-to-non-free-without-autobuild',
+            $pointer, '(in the source paragraph)', $field)
+          if !$source_fields->declares($field)
+          || $source_fields->value($field) eq 'no';
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries.pm b/lib/Lintian/Check/Binaries.pm
new file mode 100644
index 0000000..9e71f25
--- /dev/null
+++ b/lib/Lintian/Check/Binaries.pm
@@ -0,0 +1,73 @@
+# binaries -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::Compare;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /^ [^,]* \b ELF \b /x;
+
+    my @KNOWN_STRIPPED_SECTION_NAMES = qw{.note .comment};
+
+    my @elf_sections = values %{$item->elf->{'SECTION-HEADERS'}};
+    my @have_section_names = map { $_->name } @elf_sections;
+
+    my $lc_name = List::Compare->new(\@have_section_names,
+        \@KNOWN_STRIPPED_SECTION_NAMES);
+
+    my @have_stripped_sections = $lc_name->get_intersection;
+
+    # appropriately stripped, but is it stripped enough?
+    if (   $item->file_type !~ m{ \b not [ ] stripped \b }x
+        && $item->name !~ m{^ (?:usr/)? lib/ (?: debug | profile ) / }x) {
+
+        $self->pointed_hint('binary-has-unneeded-section', $item->pointer, $_)
+          for @have_stripped_sections;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/Architecture.pm b/lib/Lintian/Check/Binaries/Architecture.pm
new file mode 100644
index 0000000..009b1f5
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/Architecture.pm
@@ -0,0 +1,60 @@
+# binaries/architecture -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::Architecture;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ m{^ [^,]* \b ELF \b }x
+      || $item->file_type =~ m{ \b current [ ] ar [ ] archive \b }x;
+
+    my $architecture = $self->processable->fields->value('Architecture');
+
+    $self->pointed_hint('arch-independent-package-contains-binary-or-object',
+        $item->pointer)
+      if $architecture eq 'all';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/Architecture/Other.pm b/lib/Lintian/Check/Binaries/Architecture/Other.pm
new file mode 100644
index 0000000..b40811f
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/Architecture/Other.pm
@@ -0,0 +1,141 @@
+# binaries/architecture/other -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::Architecture::Other;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# Guile object files do not objdump/strip correctly, so exclude them
+# from a number of tests. (#918444)
+const my $GUILE_PATH_REGEX => qr{^usr/lib(?:/[^/]+)+/guile/[^/]+/.+\.go$};
+
+has ARCH_REGEX => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %arch_regex;
+
+        my $data = $self->data->load('binaries/arch-regex', qr/\s*\~\~/);
+        for my $architecture ($data->all) {
+
+            my $pattern = $data->value($architecture);
+            $arch_regex{$architecture} = qr{$pattern};
+        }
+
+        return \%arch_regex;
+    }
+);
+
+has ARCH_64BIT_EQUIVS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->load('binaries/arch-64bit-equivs',qr/\s*\=\>\s*/);
+    }
+);
+
+sub from_other_architecture {
+    my ($self, $item) = @_;
+
+    my $architecture = $self->processable->fields->value('Architecture');
+
+    return 0
+      if $architecture eq 'all';
+
+    # If it matches the architecture regex, it is good
+    return 0
+      if exists $self->ARCH_REGEX->{$architecture}
+      && $item->file_type =~ $self->ARCH_REGEX->{$architecture};
+
+    # Special case - "old" multi-arch dirs
+    if (   $item->name =~ m{(?:^|/)lib(x?\d\d)/}
+        || $item->name =~ m{^emul/ia(\d\d)}) {
+
+        my $bus_width = $1;
+
+        return 0
+          if exists $self->ARCH_REGEX->{$bus_width}
+          && $item->file_type =~ $self->ARCH_REGEX->{$bus_width};
+    }
+
+    # Detached debug symbols could be for a biarch library.
+    return 0
+      if $item->name =~ m{^usr/lib/debug/\.build-id/};
+
+    # Guile binaries do not objdump/strip (etc.) correctly.
+    return 0
+      if $item->name =~ $GUILE_PATH_REGEX;
+
+    # Allow amd64 kernel modules to be installed on i386.
+    if (   $item->name =~ m{^lib/modules/}
+        && $self->ARCH_64BIT_EQUIVS->recognizes($architecture)) {
+
+        my $equivalent_64 = $self->ARCH_64BIT_EQUIVS->value($architecture);
+
+        return 0
+          if $item->file_type =~ $self->ARCH_REGEX->{$equivalent_64};
+    }
+
+    # Ignore i386 binaries in amd64 packages for right now.
+    return 0
+      if $architecture eq 'amd64'
+      && $item->file_type =~ $self->ARCH_REGEX->{i386};
+
+    return 1;
+}
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /^ [^,]* \b ELF \b /x;
+
+    $self->pointed_hint('binary-from-other-architecture', $item->pointer)
+      if $self->from_other_architecture($item);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/Corrupted.pm b/lib/Lintian/Check/Binaries/Corrupted.pm
new file mode 100644
index 0000000..834ed31
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/Corrupted.pm
@@ -0,0 +1,93 @@
+# binaries/corrupted -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::Corrupted;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(uniq);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    $self->check_elf_issues($item);
+
+    return;
+}
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    $self->check_elf_issues($item);
+
+    return;
+}
+
+sub check_elf_issues {
+    my ($self, $item) = @_;
+
+    return unless $item->is_elf;
+
+    for (uniq @{$item->elf->{ERRORS} // []}) {
+        $self->pointed_hint('elf-error',$item->pointer, $_)
+          unless (
+            m{In program headers: Unable to find program interpreter name}
+            and $item->name =~ m{^usr/lib/debug/});
+    }
+
+    $self->pointed_hint('elf-warning', $item->pointer, $_)
+      for uniq @{$item->elf->{WARNINGS} // []};
+
+    # static library
+    for my $member_name (keys %{$item->elf_by_member}) {
+
+        my $member_elf = $item->elf_by_member->{$member_name};
+
+        $self->pointed_hint('elf-error', $item->pointer, $member_name, $_)
+          for uniq @{$member_elf->{ERRORS} // []};
+
+        $self->pointed_hint('elf-warning', $item->pointer, $member_name, $_)
+          for uniq @{$member_elf->{WARNINGS} // []};
+    }
+
+    $self->pointed_hint('binary-with-bad-dynamic-table', $item->pointer)
+      if $item->elf->{'BAD-DYNAMIC-TABLE'}
+      && $item->name !~ m{^usr/lib/debug/};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/DebugSymbols.pm b/lib/Lintian/Check/Binaries/DebugSymbols.pm
new file mode 100644
index 0000000..4afe525
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/DebugSymbols.pm
@@ -0,0 +1,72 @@
+# binaries/debug-symbols -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::DebugSymbols;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# Guile object files do not objdump/strip correctly, so exclude them
+# from a number of tests. (#918444)
+const my $GUILE_PATH_REGEX => qr{^usr/lib(?:/[^/]+)+/guile/[^/]+/.+\.go$};
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /^ [^,]* \b ELF \b /x;
+
+    # Is it an object file (which generally cannot be
+    # stripped), a kernel module, debugging symbols, or
+    # perhaps a debugging package?
+    $self->pointed_hint('unstripped-binary-or-object', $item->pointer)
+      if $item->file_type =~ m{ \b not [ ] stripped \b }x
+      && $item->name !~ m{ [.]k?o $}x
+      && $self->processable->name !~ m{ -dbg $}x
+      && $item->name !~ m{^ (?:usr/)? lib/debug/ }x
+      && $item->name !~ $GUILE_PATH_REGEX
+      && $item->name !~ m{ [.]gox $}x
+      && ( $item->file_type !~ m/executable/
+        || $item->strings !~ m{^ Caml1999X0[0-9][0-9] $}mx);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/DebugSymbols/Detached.pm b/lib/Lintian/Check/Binaries/DebugSymbols/Detached.pm
new file mode 100644
index 0000000..b4f9a4f
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/DebugSymbols/Detached.pm
@@ -0,0 +1,86 @@
+# binaries/debug-symbols/detached -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::DebugSymbols::Detached;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::Compare;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /^ [^,]* \b ELF \b /x;
+
+    return
+      unless $item->file_type =~ m{ executable | shared [ ] object }x;
+
+    # Detached debugging symbols directly in /usr/lib/debug.
+    $self->pointed_hint('debug-symbols-directly-in-usr-lib-debug',
+        $item->pointer)
+      if $item->dirname eq 'usr/lib/debug/';
+
+    return
+      unless $item->name
+      =~ m{^ usr/lib/debug/ (?:lib\d*|s?bin|usr|opt|dev|emul|\.build-id) / }x;
+
+    $self->pointed_hint('debug-symbols-not-detached', $item->pointer)
+      if exists $item->elf->{NEEDED};
+
+    # Something other than detached debugging symbols in
+    # /usr/lib/debug paths.
+    my @KNOWN_DEBUG_SECTION_NAMES
+      = qw{.debug_line .zdebug_line .debug_str .zdebug_str};
+
+    my @elf_sections = values %{$item->elf->{'SECTION-HEADERS'}};
+    my @have_section_names = map { $_->name } @elf_sections;
+
+    my $lc_name
+      = List::Compare->new(\@have_section_names, \@KNOWN_DEBUG_SECTION_NAMES);
+
+    my @have_debug_sections = $lc_name->get_intersection;
+
+    $self->pointed_hint('debug-file-with-no-debug-symbols', $item->pointer)
+      unless @have_debug_sections;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/Hardening.pm b/lib/Lintian/Check/Binaries/Hardening.pm
new file mode 100644
index 0000000..55e70ac
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/Hardening.pm
@@ -0,0 +1,183 @@
+# binaries/hardening -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::Hardening;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has HARDENED_FUNCTIONS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->load('binaries/hardened-functions');
+    }
+);
+
+has recommended_hardening_features => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %recommended_hardening_features;
+
+        my $hardening_buildflags = $self->data->hardening_buildflags;
+        my $architecture = $self->processable->fields->value('Architecture');
+
+        %recommended_hardening_features
+          = map { $_ => 1 }
+          @{$hardening_buildflags->recommended_features->{$architecture}}
+          if $architecture ne 'all';
+
+        return \%recommended_hardening_features;
+    }
+);
+
+has built_with_golang => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $built_with_golang = $self->processable->name =~ m/^golang-/;
+
+        my $source = $self->group->source;
+
+        $built_with_golang
+          = $source->relation('Build-Depends-All')
+          ->satisfies('golang-go | golang-any')
+          if defined $source;
+
+        return $built_with_golang;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    my @elf_hardened;
+    my @elf_unhardened;
+
+    for my $symbol (@{$item->elf->{SYMBOLS}}) {
+
+        next
+          unless $symbol->section eq 'UND';
+
+        if ($symbol->name =~ /^__(\S+)_chk$/) {
+
+            my $vulnerable = $1;
+            push(@elf_hardened, $vulnerable)
+              if $self->HARDENED_FUNCTIONS->recognizes($vulnerable);
+
+        } else {
+
+            push(@elf_unhardened, $symbol->name)
+              if $self->HARDENED_FUNCTIONS->recognizes($symbol->name);
+        }
+    }
+
+    $self->pointed_hint('hardening-no-fortify-functions', $item->pointer)
+      if @elf_unhardened
+      && !@elf_hardened
+      && !$self->built_with_golang
+      && $self->recommended_hardening_features->{fortify};
+
+    for my $member_name (keys %{$item->elf_by_member}) {
+
+        my @member_hardened;
+        my @member_unhardened;
+
+        for my $symbol (@{$item->elf_by_member->{$member_name}{SYMBOLS}}) {
+
+            next
+              unless $symbol->section eq 'UND';
+
+            if ($symbol->name =~ /^__(\S+)_chk$/) {
+
+                my $vulnerable = $1;
+                push(@member_hardened, $vulnerable)
+                  if $self->HARDENED_FUNCTIONS->recognizes($vulnerable);
+
+            } else {
+
+                push(@member_unhardened, $symbol->name)
+                  if $self->HARDENED_FUNCTIONS->recognizes($symbol->name);
+            }
+        }
+
+        $self->pointed_hint('hardening-no-fortify-functions',
+            $item->pointer, $member_name)
+          if @member_unhardened
+          && !@member_hardened
+          && !$self->built_with_golang
+          && $self->recommended_hardening_features->{fortify};
+    }
+
+    return
+      if $self->processable->type eq 'udeb';
+
+    return
+      unless $item->is_file;
+
+    return
+      if $item->file_type !~ m{^ [^,]* \b ELF \b }x
+      || $item->file_type !~ m{ \b executable | shared [ ] object \b }x;
+
+    # dynamically linked?
+    return
+      unless exists $item->elf->{NEEDED};
+
+    $self->pointed_hint('hardening-no-relro', $item->pointer)
+      if $self->recommended_hardening_features->{relro}
+      && !$self->built_with_golang
+      && !$item->elf->{PH}{RELRO};
+
+    $self->pointed_hint('hardening-no-bindnow', $item->pointer)
+      if $self->recommended_hardening_features->{bindnow}
+      && !$self->built_with_golang
+      && !exists $item->elf->{FLAGS_1}{NOW};
+
+    $self->pointed_hint('hardening-no-pie', $item->pointer)
+      if $self->recommended_hardening_features->{pie}
+      && !$self->built_with_golang
+      && $item->elf->{'ELF-HEADER'}{Type} =~ m{^ EXEC }x;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/LargeFileSupport.pm b/lib/Lintian/Check/Binaries/LargeFileSupport.pm
new file mode 100644
index 0000000..e64d727
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/LargeFileSupport.pm
@@ -0,0 +1,108 @@
+# binaries/large-file-support -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::LargeFileSupport;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(any);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has ARCH_REGEX => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %arch_regex;
+
+        my $data = $self->data->load('binaries/arch-regex', qr/\s*\~\~/);
+        for my $architecture ($data->all) {
+
+            my $pattern = $data->value($architecture);
+            $arch_regex{$architecture} = qr{$pattern};
+        }
+
+        return \%arch_regex;
+    }
+);
+
+has LFS_SYMBOLS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->load('binaries/lfs-symbols');
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # The LFS check only works reliably for ELF files due to the
+    # architecture regex.
+    return
+      unless $item->is_elf;
+
+    # Only 32bit ELF binaries can lack LFS.
+    return
+      unless $item->file_type =~ $self->ARCH_REGEX->{'32'};
+
+    return
+      if $item->name =~ m{^usr/lib/debug/};
+
+    my @unresolved_symbols;
+    for my $symbol (@{$item->elf->{SYMBOLS} // [] }) {
+
+        # ignore if defined in the binary
+        next
+          unless $symbol->section eq 'UND';
+
+        push(@unresolved_symbols, $symbol->name);
+    }
+
+    # Using a 32bit only interface call, some parts of the
+    # binary are built without LFS
+    $self->pointed_hint('binary-file-built-without-LFS-support',$item->pointer)
+      if any { $self->LFS_SYMBOLS->recognizes($_) } @unresolved_symbols;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/Location.pm b/lib/Lintian/Check/Binaries/Location.pm
new file mode 100644
index 0000000..c207ae0
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/Location.pm
@@ -0,0 +1,138 @@
+# binaries/location -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::Location;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+const my %PATH_DIRECTORIES => map { $_ => 1 } qw(
+  bin/ sbin/ usr/bin/ usr/sbin/ usr/games/ );
+
+has DEB_HOST_MULTIARCH => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->architectures->deb_host_multiarch;
+    }
+);
+
+has gnu_triplet_pattern => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $gnu_triplet_pattern = $EMPTY;
+
+        my $architecture = $self->processable->fields->value('Architecture');
+        my $madir = $self->DEB_HOST_MULTIARCH->{$architecture};
+
+        if (length $madir) {
+            $gnu_triplet_pattern = quotemeta $madir;
+            $gnu_triplet_pattern =~ s{^i386}{i[3-6]86};
+        }
+
+        return $gnu_triplet_pattern;
+    }
+);
+
+has ruby_triplet_pattern => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $ruby_triplet_pattern = $self->gnu_triplet_pattern;
+        $ruby_triplet_pattern =~ s{linux\\-gnu$}{linux};
+        $ruby_triplet_pattern =~ s{linux\\-gnu}{linux\\-};
+
+        return $ruby_triplet_pattern;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /^ [^,]* \b ELF \b /x
+      || $item->file_type =~ / \b current [ ] ar [ ] archive \b /x;
+
+    $self->pointed_hint('binary-in-etc', $item->pointer)
+      if $item->name =~ m{^etc/};
+
+    $self->pointed_hint('arch-dependent-file-in-usr-share', $item->pointer)
+      if $item->name =~ m{^usr/share/};
+
+    my $fields = $self->processable->fields;
+
+    my $architecture = $fields->value('Architecture');
+    my $multiarch = $fields->value('Multi-Arch') || 'no';
+
+    my $gnu_triplet_pattern = $self->gnu_triplet_pattern;
+    my $ruby_triplet_pattern = $self->ruby_triplet_pattern;
+
+    $self->pointed_hint('arch-dependent-file-not-in-arch-specific-directory',
+        $item->pointer)
+      if $multiarch eq 'same'
+      && length $gnu_triplet_pattern
+      && $item->name !~ m{\b$gnu_triplet_pattern(?:\b|_)}
+      && length $ruby_triplet_pattern
+      && $item->name !~ m{/$ruby_triplet_pattern/}
+      && $item->name !~ m{/java-\d+-openjdk-\Q$architecture\E/}
+      && $item->name !~ m{/[.]build-id/};
+
+    return
+      unless $item->file_type =~ /^ [^,]* \b ELF \b /x;
+
+    $self->pointed_hint('development-package-ships-elf-binary-in-path',
+        $item->pointer)
+      if exists $PATH_DIRECTORIES{$item->dirname}
+      && $fields->value('Section') =~ m{ (?:^|/) libdevel $}x
+      && $fields->value('Multi-Arch') ne 'foreign';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/Obsolete/Crypt.pm b/lib/Lintian/Check/Binaries/Obsolete/Crypt.pm
new file mode 100644
index 0000000..8813d8b
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/Obsolete/Crypt.pm
@@ -0,0 +1,90 @@
+# binaries/obsolete/crypt -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::Obsolete::Crypt;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has OBSOLETE_CRYPT_FUNCTIONS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->load('binaries/obsolete-crypt-functions',
+            qr/\s*\|\|\s*/);
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    for my $symbol (@{$item->elf->{SYMBOLS} // []}) {
+
+        next
+          unless $symbol->section eq 'UND';
+
+        next
+          unless $self->OBSOLETE_CRYPT_FUNCTIONS->recognizes($symbol->name);
+
+        my $tag = $self->OBSOLETE_CRYPT_FUNCTIONS->value($symbol->name);
+
+        $self->pointed_hint($tag, $item->pointer, $symbol->name);
+    }
+
+    for my $member_name (keys %{$item->elf_by_member}) {
+
+        for
+          my $symbol (@{$item->elf_by_member->{$member_name}{SYMBOLS} // []}) {
+
+            next
+              unless $symbol->section eq 'UND';
+
+            next
+              unless $self->OBSOLETE_CRYPT_FUNCTIONS->recognizes(
+                $symbol->name);
+
+            my $tag = $self->OBSOLETE_CRYPT_FUNCTIONS->value($symbol->name);
+
+            $self->pointed_hint($tag, $item->pointer, "($member_name)",
+                $symbol->name);
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/Prerequisites.pm b/lib/Lintian/Check/Binaries/Prerequisites.pm
new file mode 100644
index 0000000..cdc5868
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/Prerequisites.pm
@@ -0,0 +1,214 @@
+# binaries/prerequisites -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::Prerequisites;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any none uniq);
+
+const my $SPACE => q{ };
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+# Guile object files do not objdump/strip correctly, so exclude them
+# from a number of tests. (#918444)
+const my $GUILE_PATH_REGEX => qr{^usr/lib(?:/[^/]+)+/guile/[^/]+/.+\.go$};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has built_with_octave => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $built_with_octave = $self->processable->name =~ m/^octave-/;
+
+        my $source = $self->group->source;
+
+        $built_with_octave
+          = $source->relation('Build-Depends')->satisfies('dh-octave:any')
+          if defined $source;
+
+        return $built_with_octave;
+    }
+);
+
+has files_by_library => (is => 'rw', default => sub  { {} });
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      if $self->processable->type eq 'udeb';
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /^ [^,]* \b ELF \b /x;
+
+    return
+      unless $item->file_type =~ m{ executable | shared [ ] object }x;
+
+    my $is_shared = $item->file_type =~ m/(shared object|pie executable)/;
+
+    for my $library (@{$item->elf->{NEEDED} // [] }) {
+
+        $self->files_by_library->{$library} //= [];
+        push(@{$self->files_by_library->{$library}}, $item->name);
+    }
+
+    # Some exceptions: kernel modules, syslinux modules, detached
+    # debugging information and the dynamic loader (which itself
+    # has no dependencies).
+    $self->pointed_hint('shared-library-lacks-prerequisites', $item->pointer)
+      if $is_shared
+      && !@{$item->elf->{NEEDED} // []}
+      && $item->name !~ m{^boot/modules/}
+      && $item->name !~ m{^lib/modules/}
+      && $item->name !~ m{^usr/lib/debug/}
+      && $item->name !~ m{\.(?:[ce]32|e64)$}
+      && $item->name !~ m{^usr/lib/jvm/.*\.debuginfo$}
+      && $item->name !~ $GUILE_PATH_REGEX
+      && $item->name !~ m{
+                          ^lib(?:|32|x32|64)/
+                           (?:[-\w/]+/)?
+                           ld-[\d.]+\.so$
+                        }xsm;
+
+    my $depends = $self->processable->relation('strong');
+
+    $self->pointed_hint('undeclared-elf-prerequisites', $item->pointer,
+        $LEFT_PARENTHESIS
+          . join($SPACE, sort +uniq @{$item->elf->{NEEDED} // []})
+          . $RIGHT_PARENTHESIS)
+      if @{$item->elf->{NEEDED} // [] }
+      && $depends->is_empty;
+
+    # If there is no libc dependency, then it is most likely a
+    # bug.  The major exception is that some C++ libraries,
+    # but these tend to link against libstdc++ instead.  (see
+    # #719806)
+    my $linked_with_libc
+      = any { m{^ libc[.]so[.] }x } @{$item->elf->{NEEDED} // []};
+
+    $self->pointed_hint('library-not-linked-against-libc', $item->pointer)
+      if !$linked_with_libc
+      && $is_shared
+      && @{$item->elf->{NEEDED} // [] }
+      && (none { /^libc[.]so[.]/ } @{$item->elf->{NEEDED} // [] })
+      && $item->name !~ m{/libc\b}
+      && (!$self->built_with_octave
+        || $item->name !~ m/\.(?:oct|mex)$/);
+
+    $self->pointed_hint('program-not-linked-against-libc', $item->pointer)
+      if !$linked_with_libc
+      && !$is_shared
+      && @{$item->elf->{NEEDED} // [] }
+      && (none { /^libstdc[+][+][.]so[.]/ }@{$item->elf->{NEEDED} // [] })
+      && !$self->built_with_octave;
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $depends = $self->processable->relation('strong');
+    return
+      if $depends->is_empty;
+
+    my %libc_files;
+    for my $library (keys %{$self->files_by_library}) {
+
+        # Match libcXX or libcXX-*, but not libc3p0.
+        next
+          unless $library =~ m{^ libc [.] so [.] (\d+ .*) $}x;
+
+        my $package = "libc$1";
+
+        $libc_files{$package} //= [];
+        push(@{$libc_files{$package}}, @{$self->files_by_library->{$library}});
+    }
+
+    for my $package (keys %libc_files) {
+
+        next
+          if $depends->matches(qr/^\Q$package\E\b/);
+
+        my @sorted = sort +uniq @{$libc_files{$package}};
+
+        my $context = 'needed by ' . $sorted[0];
+        $context .= ' and ' . (scalar @sorted - 1) . ' others'
+          if @sorted > 1;
+
+        $self->hint('missing-dependency-on-libc', $context)
+          unless $self->processable->name =~ m{^ libc [\d.]+ (?:-|\z) }x;
+    }
+
+    my %libcxx_files;
+    for my $library (keys %{$self->files_by_library}) {
+
+        # Match libstdc++XX or libcstdc++XX-*
+        next
+          unless $library =~ m{^ libstdc[+][+] [.] so [.] (\d+) $}xsm;
+
+        my $package = "libstdc++$1";
+
+        $libcxx_files{$package} //= [];
+        push(@{$libcxx_files{$package}},
+            @{$self->files_by_library->{$library}});
+    }
+
+    for my $package (keys %libcxx_files) {
+
+        next
+          if $depends->matches(qr/^\Q$package\E\b/);
+
+        my @sorted = sort +uniq @{$libcxx_files{$package}};
+
+        my $context = 'needed by ' . $sorted[0];
+        $context .= ' and ' . (scalar @sorted - 1) . ' others'
+          if @sorted > 1;
+
+        $self->hint('missing-dependency-on-libstdc++', $context);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/Prerequisites/Numpy.pm b/lib/Lintian/Check/Binaries/Prerequisites/Numpy.pm
new file mode 100644
index 0000000..c1ecfc3
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/Prerequisites/Numpy.pm
@@ -0,0 +1,107 @@
+# binaries/prerequisites/numpy -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::Prerequisites::Numpy;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Lintian::Relation;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $NUMPY_REGEX => qr{
+    \Qmodule compiled against ABI version \E (?:0x)?%x
+    \Q but this version of numpy is \E (?:0x)?%x
+}x;
+
+has uses_numpy_c_abi => (is => 'rw', default => 0);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      if $item->file_type !~ m{^ [^,]* \b ELF \b }x
+      || $item->file_type !~ m{ \b executable | shared [ ] object \b }x;
+
+    # Python extension using Numpy C ABI?
+    if (   $item->name=~ m{^usr/lib/(?:pyshared/)?python2\.\d+/.*(?<!_d)\.so$}
+        || $item->name
+        =~ m{^ usr/lib/python3(?:[.]\d+)? / \S+ [.]cpython- \d+ - \S+ [.]so $}x
+    ){
+        $self->uses_numpy_c_abi(1)
+          if $item->strings =~ / numpy /msx
+          && $item->strings =~ $NUMPY_REGEX;
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    return
+      if $self->processable->type eq 'udeb';
+
+    my $depends = $self->processable->relation('strong');
+
+    # Check for dependency on python3-numpy-abiN dependency (or strict
+    # versioned dependency on python3-numpy)
+    # We do not allow alternatives as it would mostly likely
+    # defeat the purpose of this relation.  Also, we do not allow
+    # versions for -abi as it is a virtual package.
+    $self->hint('missing-dependency-on-numpy-abi')
+      if $self->uses_numpy_c_abi
+      && !$depends->matches(qr/^python3?-numpy-abi\d+$/,
+        Lintian::Relation::VISIT_OR_CLAUSE_FULL)
+      && (
+        !$depends->matches(
+            qr/^python3-numpy \(>[>=][^\|]+$/,
+            Lintian::Relation::VISIT_OR_CLAUSE_FULL
+        )
+        || !$depends->matches(
+            qr/^python3-numpy \(<[<=][^\|]+$/,
+            Lintian::Relation::VISIT_OR_CLAUSE_FULL
+        )
+      )
+      && $self->processable->name !~ m{\A python3?-numpy \Z}xsm;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/Prerequisites/Perl.pm b/lib/Lintian/Check/Binaries/Prerequisites/Perl.pm
new file mode 100644
index 0000000..a105d25
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/Prerequisites/Perl.pm
@@ -0,0 +1,81 @@
+# binaries/prerequisites/perl -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::Prerequisites::Perl;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::Relation;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has has_perl_lib => (is => 'rw', default => 0);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      if $item->file_type !~ m{^ [^,]* \b ELF \b }x
+      || $item->file_type !~ m{ \b executable | shared [ ] object \b }x;
+
+    $self->has_perl_lib(1)
+      if $item->name =~ m{^ usr/lib/ (?:[^/]+/)? perl5/ .* [.]so $}x;
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    return
+      if $self->processable->type eq 'udeb';
+
+    my $depends = $self->processable->relation('strong');
+
+    # It is a virtual package, so no version is allowed and
+    # alternatives probably does not make sense here either.
+    $self->hint('missing-dependency-on-perlapi')
+      if $self->has_perl_lib
+      && !$depends->matches(
+        qr/^perlapi-[-\w.]+(?:\s*\[[^\]]+\])?$/,
+        Lintian::Relation::VISIT_OR_CLAUSE_FULL
+      );
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/Prerequisites/Php.pm b/lib/Lintian/Check/Binaries/Prerequisites/Php.pm
new file mode 100644
index 0000000..f4f9634
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/Prerequisites/Php.pm
@@ -0,0 +1,80 @@
+# binaries/prerequisites/php -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::Prerequisites::Php;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::Relation;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has has_php_ext => (is => 'rw', default => 0);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      if $item->file_type !~ m{^ [^,]* \b ELF \b }x
+      || $item->file_type !~ m{ \b executable | shared [ ] object \b }x;
+
+    # PHP extension?
+    $self->has_php_ext(1)
+      if $item->name =~ m{^usr/lib/php\d/.*\.so(?:\.\d+)*$};
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    return
+      if $self->processable->type eq 'udeb';
+
+    my $depends = $self->processable->relation('strong');
+
+    # It is a virtual package, so no version is allowed and
+    # alternatives probably does not make sense here either.
+    $self->hint('missing-dependency-on-phpapi')
+      if $self->has_php_ext
+      && !$depends->matches(qr/^phpapi-[\d\w+]+$/,
+        Lintian::Relation::VISIT_OR_CLAUSE_FULL);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/Profiling.pm b/lib/Lintian/Check/Binaries/Profiling.pm
new file mode 100644
index 0000000..4b52937
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/Profiling.pm
@@ -0,0 +1,73 @@
+# binaries/profiling -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::Profiling;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    my $architecture = $self->processable->fields->value('Architecture');
+
+    my $is_profiled = 0;
+
+    for my $symbol (@{$item->elf->{SYMBOLS} // [] }) {
+
+        # According to the binutils documentation[1], the profiling symbol
+        # can be named "mcount", "_mcount" or even "__mcount".
+        # [1] http://sourceware.org/binutils/docs/gprof/Implementation.html
+        $is_profiled = 1
+          if $symbol->version =~ /^GLIBC_.*/
+          && $symbol->name =~ m{\A _?+ _?+ (gnu_)?+mcount(_nc)?+ \Z}xsm
+          && ($symbol->section eq 'UND' || $symbol->section eq '.text');
+
+        # This code was used to detect profiled code in Wheezy and earlier
+        $is_profiled = 1
+          if $symbol->section eq '.text'
+          && $symbol->version eq 'Base'
+          && $symbol->name eq '__gmon_start__'
+          && $architecture ne 'hppa';
+    }
+
+    $self->pointed_hint('binary-compiled-with-profiling-enabled',
+        $item->pointer)
+      if $is_profiled;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/Rpath.pm b/lib/Lintian/Check/Binaries/Rpath.pm
new file mode 100644
index 0000000..a4ecb93
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/Rpath.pm
@@ -0,0 +1,145 @@
+# binaries/rpath -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::Rpath;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use File::Spec;
+use List::SomeUtils qw(any);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SLASH => q{/};
+
+has DEB_HOST_MULTIARCH => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->architectures->deb_host_multiarch;
+    }
+);
+
+has multiarch_component => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $architecture = $self->processable->fields->value('Architecture');
+        my $multiarch_component = $self->DEB_HOST_MULTIARCH->{$architecture};
+
+        return $multiarch_component;
+    }
+);
+
+has private_folders => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my @lib_folders = qw{lib};
+
+        push(@lib_folders,
+            map { $_ . $SLASH . $self->multiarch_component } @lib_folders)
+          if length $self->multiarch_component;
+
+        my @usrlib_folders = qw{usr/lib};
+
+        push(@usrlib_folders,
+            map { $_ . $SLASH . $self->multiarch_component } @usrlib_folders)
+          if length $self->multiarch_component;
+
+        my @game_folders = map { "$_/games" } @usrlib_folders;
+
+        my @private_folders
+          = map { $_ . $SLASH . $self->processable->source_name }
+          (@lib_folders, @usrlib_folders, @game_folders);
+
+        return \@private_folders;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /^ [^,]* \b ELF \b /x;
+
+    for my $section (qw{RPATH RUNPATH}) {
+
+        my @rpaths = keys %{$item->elf->{$section} // {}};
+
+        my @no_origin = grep { !m{^ \$ \{? ORIGIN \}? }x } @rpaths;
+
+        my @canonical = map { File::Spec->canonpath($_) } @no_origin;
+
+        my @custom;
+        for my $folder (@canonical) {
+
+            # for shipped folders, would have to disallow system locations
+            next
+              if any { $folder =~ m{^ / \Q$_\E }x } @{$self->private_folders};
+
+            # GHC in Debian uses a scheme for RPATH (#914873)
+            next
+              if $folder =~ m{^ /usr/lib/ghc (?: / | $ ) }x;
+
+            push(@custom, $folder);
+        }
+
+        my @absolute = grep { m{^ / }x } @custom;
+
+        $self->pointed_hint('custom-library-search-path',
+            $item->pointer, $section, $_)
+          for @absolute;
+
+        my @relative = grep { m{^ [^/] }x } @custom;
+
+        $self->pointed_hint('relative-library-search-path',
+            $item->pointer, $section, $_)
+          for @relative;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/Spelling.pm b/lib/Lintian/Check/Binaries/Spelling.pm
new file mode 100644
index 0000000..38a2529
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/Spelling.pm
@@ -0,0 +1,86 @@
+# binaries/spelling -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::Spelling;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::Spelling qw(check_spelling);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has BINARY_SPELLING_EXCEPTIONS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->load('binaries/spelling-exceptions',qr/\s+/);
+    }
+);
+
+sub spelling_tag_emitter {
+    my ($self, $tag_name, $item, @orig_args) = @_;
+
+    return sub {
+
+        my $pointer = $item->pointer($.);
+
+        return $self->pointed_hint($tag_name, $pointer, @orig_args, @_);
+    };
+}
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /^ [^,]* \b ELF \b /x;
+
+    my @acceptable = (
+        @{ $self->group->spelling_exceptions },
+        $self->BINARY_SPELLING_EXCEPTIONS->all
+    );
+
+    my $tag_emitter
+      = $self->spelling_tag_emitter('spelling-error-in-binary', $item);
+
+    check_spelling($self->data, $item->strings, \@acceptable, $tag_emitter, 0);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Binaries/Static.pm b/lib/Lintian/Check/Binaries/Static.pm
new file mode 100644
index 0000000..47eafb8
--- /dev/null
+++ b/lib/Lintian/Check/Binaries/Static.pm
@@ -0,0 +1,100 @@
+# binaries/static -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Binaries::Static;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has built_with_golang => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $built_with_golang = $self->processable->name =~ m/^golang-/;
+
+        my $source = $self->group->source;
+
+        $built_with_golang
+          = $source->relation('Build-Depends-All')
+          ->satisfies('golang-go | golang-any')
+          if defined $source;
+
+        return $built_with_golang;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      if $self->processable->type eq 'udeb';
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /^ [^,]* \b ELF \b /x;
+
+    return
+      unless $item->file_type =~ m{ executable | shared [ ] object }x;
+
+    my $is_shared = $item->file_type =~ m/(shared object|pie executable)/;
+
+    # Some exceptions: files in /boot, /usr/lib/debug/*,
+    # named *-static or *.static, or *-static as
+    # package-name.
+    # Binaries built by the Go compiler are statically
+    # linked by default.
+    # klibc binaries appear to be static.
+    # Location of debugging symbols.
+    # ldconfig must be static.
+    $self->pointed_hint('statically-linked-binary', $item->pointer)
+      if !$is_shared
+      && !exists $item->elf->{NEEDED}
+      && $item->name !~ m{^boot/}
+      && $item->name !~ /[\.-]static$/
+      && $self->processable->name !~ /-static$/
+      && !$self->built_with_golang
+      && (!exists $item->elf->{INTERP}
+        || $item->elf->{INTERP} !~ m{/lib/klibc-\S+\.so})
+      && $item->name !~ m{^usr/lib/debug/}
+      && $item->name ne 'sbin/ldconfig';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/BuildSystems/Automake.pm b/lib/Lintian/Check/BuildSystems/Automake.pm
new file mode 100644
index 0000000..07a7d6d
--- /dev/null
+++ b/lib/Lintian/Check/BuildSystems/Automake.pm
@@ -0,0 +1,54 @@
+# build-systems/automake -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2013 Gautier Minster
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::BuildSystems::Automake;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    # automake probably isn't used without a Makefile.am
+    my $makefile = $self->processable->patched->lookup('Makefile.am');
+    return
+      unless defined $makefile;
+
+    my $configure_in = $self->processable->patched->lookup('configure.in');
+
+    $self->pointed_hint('deprecated-configure-filename',$configure_in->pointer)
+      if defined $configure_in;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/BuildSystems/Autotools.pm b/lib/Lintian/Check/BuildSystems/Autotools.pm
new file mode 100644
index 0000000..cf40183
--- /dev/null
+++ b/lib/Lintian/Check/BuildSystems/Autotools.pm
@@ -0,0 +1,88 @@
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::BuildSystems::Autotools;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    if (   $item->name =~ /configure\.(in|ac)$/
+        && $item->is_open_ok) {
+
+        open(my $fd, '<', $item->unpacked_path)
+          or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+        my $position = 1;
+        while (my $line = <$fd>) {
+
+            next
+              if $line =~ m{^ \s* dnl }x;
+
+            if ($line
+                =~ m{ (AC_PATH_PROG) \s* [(] [^,]+ , \s* \[? pkg-config \]? \s* , }x
+            ){
+
+                my $macro = $1;
+                $self->pointed_hint(
+                    'autotools-pkg-config-macro-not-cross-compilation-safe',
+                    $item->pointer($position), $macro);
+            }
+
+        } continue {
+            ++$position;
+        }
+
+        close $fd;
+    }
+
+    # Tests of autotools files are a special case.  Ignore
+    # debian/config.cache as anyone doing that probably knows what
+    # they're doing and is using it as part of the build.
+    $self->pointed_hint('configure-generated-file-in-source', $item->pointer)
+      if $item->basename =~ m{\A config.(?:cache|log|status) \Z}xsm
+      && $item->name !~ m{^ debian/ }sx;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/BuildSystems/Autotools/Libtool.pm b/lib/Lintian/Check/BuildSystems/Autotools/Libtool.pm
new file mode 100644
index 0000000..3f0865a
--- /dev/null
+++ b/lib/Lintian/Check/BuildSystems/Autotools/Libtool.pm
@@ -0,0 +1,99 @@
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::BuildSystems::Autotools::Libtool;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $ACCEPTABLE_LIBTOOL_MAJOR => 5;
+const my $ACCEPTABLE_LIBTOOL_MINOR => 2;
+const my $ACCEPTABLE_LIBTOOL_DEBIAN => 2;
+
+# Check if the package build-depends on autotools-dev, automake,
+# or libtool.
+my $LIBTOOL = Lintian::Relation->new->load('libtool | dh-autoreconf');
+has libtool_in_build_depends => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->processable->relation('Build-Depends-All')
+          ->satisfies($LIBTOOL);
+    }
+);
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    $self->pointed_hint('ancient-libtool', $item->pointer)
+      if $item->basename eq 'ltconfig'
+      && $item->name !~ m{^ debian/ }sx
+      && !$self->libtool_in_build_depends;
+
+    if (   $item->basename eq 'ltmain.sh'
+        && $item->name !~ m{^ debian/ }sx
+        && !$self->libtool_in_build_depends) {
+
+        if ($item->bytes =~ /^VERSION=[\"\']?(1\.(\d)\.(\d+)(?:-(\d))?)/m) {
+            my ($version, $major, $minor, $debian)=($1, $2, $3, $4);
+
+            $debian //= 0;
+
+            $self->pointed_hint('ancient-libtool', $item->pointer, $version)
+              if $major < $ACCEPTABLE_LIBTOOL_MAJOR
+              || (
+                $major == $ACCEPTABLE_LIBTOOL_MAJOR
+                && (
+                    $minor < $ACCEPTABLE_LIBTOOL_MINOR
+                    || (   $minor == $ACCEPTABLE_LIBTOOL_MINOR
+                        && $debian < $ACCEPTABLE_LIBTOOL_DEBIAN)
+                )
+              );
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/BuildSystems/Cmake.pm b/lib/Lintian/Check/BuildSystems/Cmake.pm
new file mode 100644
index 0000000..0dfaf2c
--- /dev/null
+++ b/lib/Lintian/Check/BuildSystems/Cmake.pm
@@ -0,0 +1,73 @@
+# build-systems/cmake -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::BuildSystems::Cmake;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # Check for CMake cache files.  These embed the source path and hence
+    # will cause FTBFS on buildds, so they should never be present
+    $self->pointed_hint('source-contains-cmake-cache-file', $item->pointer)
+      if $item->basename eq 'CMakeCache.txt';
+
+    return;
+}
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # /usr/share/cmake-*
+    $self->pointed_hint('package-contains-cmake-private-file', $item->pointer)
+      if $item->name =~ m{^ usr/share/cmake- \d+ [.] \d+ / }x
+      && $self->processable->source_name ne 'cmake';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/BuildSystems/Debhelper/MaintainerScript/Token.pm b/lib/Lintian/Check/BuildSystems/Debhelper/MaintainerScript/Token.pm
new file mode 100644
index 0000000..7d54b79
--- /dev/null
+++ b/lib/Lintian/Check/BuildSystems/Debhelper/MaintainerScript/Token.pm
@@ -0,0 +1,80 @@
+# build-systems/debhelper/maintainer-script/token -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::BuildSystems::Debhelper::MaintainerScript::Token;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_maintainer_script;
+
+    return
+      unless length $item->interpreter;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        next
+          unless $line =~ m{( [#] DEBHELPER [#] )}x;
+
+        my $token = $1;
+
+        my $pointer = $item->pointer($position);
+
+        $self->pointed_hint('maintainer-script-has-unexpanded-debhelper-token',
+            $pointer, $token);
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/BuildSystems/Libtool/LaFile.pm b/lib/Lintian/Check/BuildSystems/Libtool/LaFile.pm
new file mode 100644
index 0000000..7431c41
--- /dev/null
+++ b/lib/Lintian/Check/BuildSystems/Libtool/LaFile.pm
@@ -0,0 +1,94 @@
+# build-systems/libtool/la-file -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2018-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::BuildSystems::Libtool::LaFile;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SLASH => q{/};
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      if $item->name !~ /[.]la$/ || length $item->link;
+
+    my @lines = split(/\n/, $item->decoded_utf8);
+
+    my $position = 1;
+    for my $line (@lines) {
+
+        if ($line =~ /^ libdir=' (.+) ' $/x) {
+
+            my $own_location = $1;
+            $own_location =~ s{^/+}{};
+            $own_location =~ s{/*$}{/};
+
+            # python-central is a special case since the
+            # libraries are moved at install time.
+            next
+              if $own_location
+              =~ m{^ usr/lib/python [\d.]+ / (?:site|dist)-packages / }x
+              && $item->dirname =~ m{^ usr/share/pyshared/ }x;
+
+            $self->pointed_hint(
+                'incorrect-libdir-in-la-file',
+                $item->pointer($position),
+                "$own_location != " . $item->dirname
+            ) unless $own_location eq $item->dirname;
+
+        }
+
+        if ($line =~ /^ dependency_libs=' (.+) ' $/x){
+
+            my $prerequisites = $1;
+
+            $self->pointed_hint(
+                'non-empty-dependency_libs-in-la-file',
+                $item->pointer($position),
+                $prerequisites
+            );
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/BuildSystems/Waf.pm b/lib/Lintian/Check/BuildSystems/Waf.pm
new file mode 100644
index 0000000..4825a11
--- /dev/null
+++ b/lib/Lintian/Check/BuildSystems/Waf.pm
@@ -0,0 +1,87 @@
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::BuildSystems::Waf;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->basename =~ m{ \b waf $}x;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $marker = 0;
+
+    while (my $line = <$fd>) {
+
+        next
+          unless $line =~ m/^#/;
+
+        if ($marker && $line =~ m/^#BZ[h0][0-9]/) {
+
+            # waf is not allowed
+            $self->pointed_hint('source-contains-waf-binary', $item->pointer);
+            last;
+        }
+
+        $marker = 1
+          if $line =~ m/^#==>/;
+
+        # We could probably stop here, but just in case
+        $marker = 0
+          if $line =~ m/^#<==/;
+    }
+
+    close $fd;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/ChangesFile.pm b/lib/Lintian/Check/ChangesFile.pm
new file mode 100644
index 0000000..617de64
--- /dev/null
+++ b/lib/Lintian/Check/ChangesFile.pm
@@ -0,0 +1,121 @@
+# changes-file -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+#
+# This program is free software.  It is distributed under the terms of
+# the GNU General Public License as published by the Free Software
+# Foundation; either version 2 of the License, or (at your option) any
+# later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::ChangesFile;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::Compare;
+use List::SomeUtils qw(uniq);
+use Path::Tiny;
+
+use Lintian::Util qw(get_file_checksum);
+
+const my $NOT_EQUALS => q{!=};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub changes {
+    my ($self) = @_;
+
+    my %count_by_algorithm;
+
+    for my $basename (keys %{$self->processable->files}) {
+
+        my $details = $self->processable->files->{$basename};
+
+        $self->hint('bad-section-in-changes-file', $basename,
+            $details->{section})
+          if $details->{section} eq 'non-free'
+          || $details->{section} eq 'contrib';
+
+        # take from location near input file
+        my $physical_path
+          = path($self->processable->path)->sibling($basename)->stringify;
+        my $actual_size = -s $physical_path;
+
+        # check size
+        $self->hint('file-size-mismatch-in-changes-file',
+            $basename, $details->{size}, $NOT_EQUALS, $actual_size)
+          unless $details->{size} == $actual_size;
+
+        for my $algorithm (qw(Md5 Sha1 Sha256)) {
+
+            my $checksum_info = $details->{checksums}{$algorithm};
+            next
+              unless defined $checksum_info;
+
+            $self->hint('file-size-mismatch-in-changes-file',
+                $basename,$details->{size}, $NOT_EQUALS,
+                $checksum_info->{filesize})
+              unless $details->{size} == $checksum_info->{filesize};
+
+            my $actual_checksum= get_file_checksum($algorithm, $physical_path);
+
+            $self->hint('checksum-mismatch-in-changes-file',
+                "Checksum-$algorithm", $basename)
+              unless $checksum_info->{sum} eq $actual_checksum;
+
+            ++$count_by_algorithm{$algorithm};
+        }
+    }
+
+    my @installables= grep { m{ [.]deb $}x } keys %{$self->processable->files};
+    my @installable_names = map { m{^ ([^_]+) _ }x } @installables;
+    my @stems = uniq map { m{^ (.+) -dbg (?:sym) $}x } @installable_names;
+
+    for my $stem (@stems) {
+
+        my @conflicting = ("$stem-dbg", "$stem-dbgsym");
+
+        my $lc = List::Compare->new(\@conflicting, \@installable_names);
+        $self->hint('package-builds-dbg-and-dbgsym-variants',
+            (sort @conflicting))
+          if $lc->is_LsubsetR;
+    }
+
+    # Check that we have a consistent number of checksums and files
+    for my $algorithm (keys %count_by_algorithm) {
+
+        my $actual_count = $count_by_algorithm{$algorithm};
+        my $expected_count = scalar keys %{$self->processable->files};
+
+        $self->hint('checksum-count-mismatch-in-changes-file',
+"$actual_count Checksum-$algorithm checksums != $expected_count files"
+        ) if $actual_count != $expected_count;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Conffiles.pm b/lib/Lintian/Check/Conffiles.pm
new file mode 100644
index 0000000..076c17f
--- /dev/null
+++ b/lib/Lintian/Check/Conffiles.pm
@@ -0,0 +1,136 @@
+# conffiles -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2017 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Conffiles;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::Compare;
+use List::SomeUtils qw(any none);
+use Path::Tiny;
+
+const my $SPACE => q{ };
+
+const my @KNOWN_INSTRUCTIONS => qw(remove-on-upgrade);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      if $self->processable->type =~ 'udeb';
+
+    my $declared_conffiles = $self->processable->declared_conffiles;
+
+    unless ($item->is_file) {
+        $self->pointed_hint('conffile-has-bad-file-type', $item->pointer)
+          if $declared_conffiles->is_known($item->name);
+        return;
+    }
+
+    # files /etc must be conffiles, with some exceptions).
+    $self->pointed_hint('file-in-etc-not-marked-as-conffile',$item->pointer)
+      if $item->name =~ m{^etc/}
+      && !$declared_conffiles->is_known($item->name)
+      && $item->name !~ m{/README$}
+      && $item->name !~ m{^ etc/init[.]d/ (?: skeleton | rc S? ) $}x;
+
+    return;
+}
+
+sub binary {
+    my ($self) = @_;
+
+    my $declared_conffiles = $self->processable->declared_conffiles;
+    for my $relative ($declared_conffiles->all) {
+
+        my $item = $self->processable->conffiles_item;
+
+        my @entries = @{$declared_conffiles->by_file->{$relative}};
+
+        my @positions = map { $_->position } @entries;
+        my $lines = join($SPACE, (sort { $a <=> $b } @positions));
+
+        $self->pointed_hint('duplicate-conffile', $item->pointer,
+            $relative, "(lines $lines)")
+          if @entries > 1;
+
+        for my $entry (@entries) {
+
+            my $conffiles_item = $self->processable->conffiles_item;
+            my $pointer = $conffiles_item->pointer($entry->position);
+
+            $self->pointed_hint('relative-conffile', $pointer,$relative)
+              if $entry->is_relative;
+
+            $self->pointed_hint('file-in-etc-rc.d-marked-as-conffile',
+                $pointer, $relative)
+              if $relative =~ m{^etc/rc.\.d/};
+
+            $self->pointed_hint('file-in-usr-marked-as-conffile',
+                $pointer, $relative)
+              if $relative =~ m{^usr/};
+
+            $self->pointed_hint('non-etc-file-marked-as-conffile',
+                $pointer, $relative)
+              unless $relative =~ m{^etc/};
+
+            my @instructions = @{$entry->instructions};
+
+            my $instruction_lc
+              = List::Compare->new(\@instructions, \@KNOWN_INSTRUCTIONS);
+            my @unknown = $instruction_lc->get_Lonly;
+
+            $self->pointed_hint('unknown-conffile-instruction', $pointer, $_)
+              for @unknown;
+
+            my $should_exist= none { $_ eq 'remove-on-upgrade' } @instructions;
+            my $may_not_exist= any { $_ eq 'remove-on-upgrade' } @instructions;
+
+            my $shipped = $self->processable->installed->lookup($relative);
+
+            $self->pointed_hint('missing-conffile', $pointer, $relative)
+              if $should_exist && !defined $shipped;
+
+            $self->pointed_hint('unexpected-conffile', $pointer, $relative)
+              if $may_not_exist && defined $shipped;
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/ContinuousIntegration/Salsa.pm b/lib/Lintian/Check/ContinuousIntegration/Salsa.pm
new file mode 100644
index 0000000..3faa978
--- /dev/null
+++ b/lib/Lintian/Check/ContinuousIntegration/Salsa.pm
@@ -0,0 +1,103 @@
+# continuous-integration/salsa -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::ContinuousIntegration::Salsa;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Data::DPath qw(dpath);
+use List::SomeUtils qw(any);
+use Scalar::Util qw(reftype);
+use YAML::XS qw(LoadFile);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# ci is configured in gitlab and can be located anywere
+# https://salsa.debian.org/salsa-ci-team/pipeline/-/issues/86
+my @KNOWN_LOCATIONS = qw(
+  debian/salsa-ci.yml
+  debian/gitlab-ci.yml
+  gitlab-ci.yml
+  .gitlab-ci.yml
+);
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless any { $item->name eq $_ } @KNOWN_LOCATIONS;
+
+    $self->pointed_hint('specification', $item->pointer);
+
+    return
+      unless $item->is_open_ok;
+
+    my $yaml = LoadFile($item->unpacked_path);
+    return
+      unless defined $yaml;
+
+# traditionally examined via codesearch
+# https://codesearch.debian.net/search?q=salsa-ci-team%2Fpipeline%2Fraw%2Fmaster%2Fsalsa-ci.yml&literal=1
+    my @items = dpath('//include')->match($yaml);
+
+    my @includes;
+    for my $item (@items) {
+
+        my $item_type = reftype $item;
+
+        if (!length $item_type) {
+            push(@includes, $item);
+
+        } elsif ($item_type eq 'ARRAY') {
+            for my $element (@{$item}) {
+
+                my $element_type = reftype $element;
+                if (!length $element_type) {
+                    push(@includes, $element);
+
+                } elsif ($element_type eq 'HASH') {
+                    # new Gitlab style with desciptors
+                    push(@includes, $element->{file})
+                      if exists $element->{file};
+                }
+            }
+        }
+    }
+
+    $self->pointed_hint('include', $item->pointer, $_) for @includes;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/ControlFiles.pm b/lib/Lintian/Check/ControlFiles.pm
new file mode 100644
index 0000000..d0c44a2
--- /dev/null
+++ b/lib/Lintian/Check/ControlFiles.pm
@@ -0,0 +1,132 @@
+# control-files -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2017 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::ControlFiles;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+
+const my $WIDELY_EXECUTABLE => oct(111);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has ships_ctrl_script => (is => 'rw', default =>  0);
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    my $type = $self->processable->type;
+    my $processable = $self->processable;
+
+    my $DEB_PERMISSIONS
+      = $self->data->load('control-files/deb-permissions',qr/\s+/);
+    my $UDEB_PERMISSIONS
+      = $self->data->load('control-files/udeb-permissions',qr/\s+/);
+
+    my $ctrl = $type eq 'udeb' ? $UDEB_PERMISSIONS : $DEB_PERMISSIONS;
+    my $ctrl_alt = $type eq 'udeb' ? $DEB_PERMISSIONS : $UDEB_PERMISSIONS;
+
+    # the control.tar.gz should only contain files (and the "root"
+    # dir, but that is excluded from the index)
+    if (!$item->is_regular_file) {
+
+        $self->pointed_hint('control-file-is-not-a-file', $item->pointer);
+        # Doing further checks is probably not going to yield anything
+        # remotely useful.
+        return;
+    }
+
+    # valid control file?
+    unless ($ctrl->recognizes($item->name)) {
+
+        if ($ctrl_alt->recognizes($item->name)) {
+            $self->pointed_hint('not-allowed-control-file', $item->pointer);
+
+        } else {
+            $self->pointed_hint('unknown-control-file', $item->pointer);
+        }
+
+        return;
+    }
+
+    my $experm = oct($ctrl->value($item->name));
+
+    $self->pointed_hint('control-file-is-empty', $item->pointer)
+      if $item->size == 0
+      && $item->basename ne 'md5sums';
+
+    # skip `control' control file (that's an exception: dpkg
+    # doesn't care and this file isn't installed on the systems
+    # anyways)
+    return
+      if $item->name eq 'control';
+
+    my $operm = $item->operm;
+    if ($item->is_executable || $experm & $WIDELY_EXECUTABLE) {
+
+        $self->ships_ctrl_script(1);
+        $self->pointed_hint('ctrl-script', $item->pointer);
+    }
+
+    # correct permissions?
+    unless ($operm == $experm) {
+
+        $self->pointed_hint('control-file-has-bad-permissions',
+            $item->pointer,sprintf('%04o != %04o', $operm, $experm));
+    }
+
+    # correct owner?
+    unless ($item->identity eq 'root/root' || $item->identity eq '0/0') {
+
+        $self->pointed_hint('control-file-has-bad-owner',$item->pointer,
+            $item->identity,'!= root/root (or 0/0)');
+    }
+
+    # for other maintainer scripts checks, see the scripts check
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    $self->hint('no-ctrl-scripts')
+      unless $self->ships_ctrl_script;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Cron.pm b/lib/Lintian/Check/Cron.pm
new file mode 100644
index 0000000..cca2420
--- /dev/null
+++ b/lib/Lintian/Check/Cron.pm
@@ -0,0 +1,67 @@
+# cron -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Cron;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $READ_WRITE_PERMISSIONS => oct(644);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->name =~ m{^ etc/cron }x;
+
+    # /etc/cron.daily, etc.
+    # NB: cron ships ".placeholder" files, which shouldn't be run.
+    $self->pointed_hint('run-parts-cron-filename-contains-illegal-chars',
+        $item->pointer)
+      if $item->name
+      =~ m{^ etc/cron[.] (?: daily | hourly | monthly | weekly |d ) / [^.] .* [+.] }x;
+
+    # /etc/cron.d
+    # NB: cron ships ".placeholder" files in etc/cron.d,
+    # which we shouldn't tag.
+    $self->pointed_hint('bad-permissions-for-etc-cron.d-script',
+        $item->pointer,
+        sprintf('%04o != %04o', $item->operm, $READ_WRITE_PERMISSIONS))
+      if $item->name =~ m{ ^ etc/cron\.d/ [^.] }msx
+      && $item->operm != $READ_WRITE_PERMISSIONS;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Cruft.pm b/lib/Lintian/Check/Cruft.pm
new file mode 100644
index 0000000..1a402c6
--- /dev/null
+++ b/lib/Lintian/Check/Cruft.pm
@@ -0,0 +1,836 @@
+# cruft -- lintian check script -*- perl -*-
+#
+# based on debhelper check,
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Cruft;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any none);
+
+const my $EMPTY => q{};
+const my $ASTERISK => q{*};
+const my $DOT => q{.};
+
+const my $ITEM_NOT_FOUND => -1;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# Half of the size used in the "sliding window" for detecting bad
+# licenses like GFDL with invariant sections.
+# NB: Keep in sync cruft-gfdl-fp-sliding-win/pre_build.
+# not less than 8192 for source missing
+use constant BLOCKSIZE => 16_384;
+use Lintian::SlidingWindow;
+
+my %NVIDIA_LICENSE = (
+    keywords => [qw{license intellectual retain property}],
+    sentences =>[
+'retain all intellectual property and proprietary rights in and to this software and related documentation'
+    ]
+);
+
+my %NON_FREE_LICENSES = (
+# first field is tag
+# second field is a list of keywords in lower case
+# third field are lower case sentences to match the license. Notes that space are normalized before and formatting removed
+# fourth field is a regex to use to match the license, use lower case and [ ] for space.
+# 5th field is a function to call if the field 2th to 5th match.
+# (see dispatch table %LICENSE_CHECK_DISPATCH_TABLE
+
+    # json license
+    'license-problem-json-evil' => {
+        keywords => [qw{software evil good}],
+        sentences => ['software shall be used for good'],
+        regex =>
+qr{software [ ] shall [ ] be [ ] used [ ] for [ ] good [ ]? ,? [ ]? not [ ] evil}msx
+    },
+    # non free RFC old version
+    'license-problem-non-free-RFC' => {
+        keywords => [qw{document purpose translate language}],
+        sentences => ['this document itself may not be modified in any way'],
+        regex =>
+qr{this [ ] document [ ] itself [ ] may [ ] not [ ] be [ ] modified [ ] in [ ] any [ ] way [ ]?,
+        [ ]? such [ ] as [ ] by [ ] removing [ ] the [ ] copyright [ ] notice [ ] or [ ] references
+        [ ] to [ ] .{0,256} [ ]? except [ ] as [ ] needed [ ] for [ ] the [ ] purpose [ ] of [ ] developing
+        [ ] .{0,128} [ ]? in [ ] which [ ] case [ ] the [ ] procedures [ ] for [ ] copyrights [ ] defined
+        [ ] in [ ] the [ ] .{0,128} [ ]? process [ ] must [ ] be [ ] followed[ ]?,[ ]?
+        or [ ] as [ ] required [ ] to [ ] translate [ ] it [ ] into [ ] languages [ ]}msx,
+        callsub => 'rfc_whitelist_filename'
+    },
+    'license-problem-non-free-RFC-BCP78' => {
+        keywords => [qw{license document bcp restriction}],
+        sentences => ['bcp 78'],
+        regex =>
+qr{this [ ] document [ ] is [ ] subject [ ] to [ ] (?:the [ ] rights [ ]?, [ ] licenses [ ] and [ ]restrictions [ ] contained [ ] in [ ])? bcp [ ] 78}msx,
+        callsub => 'rfc_whitelist_filename'
+    },
+# check GFDL block - The ".{0,1024}"-part in the regex
+# will contain the "no invariants etc."  part if
+# it is a good use of the license.  We include it
+# here to ensure that we do not emit a false positive
+# if the "redeeming" part is in the next block
+# keyword document is here in order to benefit for other license keyword and a shortcut for documentation
+    'license-problem-gfdl-invariants' => {
+        keywords => [qw{license document gnu copy documentation}],
+        sentences => ['gnu free documentation license'],
+        regex =>
+qr{(?'rawcontextbefore'(?:(?:(?!a [ ] copy [ ] of [ ] the [ ] license [ ] is).){1024}|
+\A(?:(?!a [ ] copy [ ] of [ ] the [ ] license [ ] is).){0,1024}|
+(?:[ ] copy [ ] of [ ] the [ ] license [ ] is.{0,1024}?))) gnu [ ] free [ ]
+documentation [ ] license (?'rawgfdlsections'(?:(?!gnu [ ] free [ ] documentation
+[ ] license).){0,1024}?) (?:a [ ] copy [ ] of [ ] the [ ] license [ ] is|
+this [ ] document [ ] is [ ] distributed)}msx,
+        callsub => 'check_gfdl_license_problem'
+    },
+    # php license
+    'license-problem-php-license' => {
+        keywords => [qw{www.php.net group\@php.net phpfoo conjunction php}],
+        sentences => ['this product includes php'],
+        regex => qr{php [ ] license [ ]?[,;][ ]? version [ ] 3(?:\.\d+)?}msx,
+        callsub => 'php_source_whitelist'
+    },
+    'license-problem-bad-php-license' => {
+        keywords => [qw{www.php.net add-on conjunction}],
+        sentences => ['this product includes php'],
+        regex => qr{php [ ] license [ ]?[,;][ ]? version [ ] 2(?:\.\d+)?}msx,
+        callsub => 'php_source_whitelist'
+    },
+    # cc by nc sa note that " is replaced by [ ]
+    'license-problem-cc-by-nc-sa' => {
+        keywords => [qw{license by-nc-sa creativecommons.org}],
+        sentences => [
+            '://creativecommons.org/licenses/by-nc-sa',
+            'under attribution-noncommercial'
+        ],
+        regex =>
+qr{(?:license [ ] rdf:[^=:]+=[ ]* (?:ht|f)tps?://(?:[^/.]\.)??creativecommons\.org/licenses/by-nc-sa/\d+(?:\.\d+)?(?:/[[:alpha:]]+)?/? [ ]* >|available [ ] under [ ] attribution-noncommercial)}msx
+    },
+    # not really a license but warn it: visual c++ generated file
+    'source-contains-autogenerated-visual-c++-file' => {
+        keywords => [qw{microsoft visual generated}],
+        sentences => ['microsoft visual c++ generated'],
+        regex =>
+qr{microsoft [ ] visual [ ] c[+][+] [ ] generated (?![ ] by [ ] freeze\.py)}msx
+    },
+    # not really a license but warn about it: gperf generated file
+    'source-contains-autogenerated-gperf-data' => {
+        keywords => [qw{code produced gperf version}],
+        sentences => ['code produced by gperf version'],
+        regex =>
+          qr{code [ ] produced [ ] by [ ] gperf [ ] version [ ] \d+\.\d+}msx
+    },
+    # warn about copy of ieee-data
+    'source-contains-data-from-ieee-data-oui-db' => {
+        keywords => [qw{struck scitex racore}],
+        sentences => ['dr. b. struck'],
+        regex => qr{dr. [ ] b. [ ] struck}msx
+    },
+    # warn about unicode license for utf for convert utf
+    'license-problem-convert-utf-code' => {
+        keywords => [qw{fall-through bytestowrite utf-8}],
+        sentences => ['the fall-through switches in utf-8 reading'],
+        regex =>
+qr{the [ ] fall-through [ ] switches [ ] in [ ] utf-8 [ ] reading [ ] code [ ] save}msx
+    }
+);
+
+# get usual data about admissible/not admissible GFDL invariant part of license
+has GFDL_FRAGMENTS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %gfdl_fragments;
+
+        my $data = $self->data->load('cruft/gfdl-license-fragments-checks',
+            qr/\s*\~\~\s*/);
+
+        for my $gfdlsectionsregex ($data->all) {
+
+            my $secondpart = $data->value($gfdlsectionsregex);
+
+            # allow empty parameters
+            $secondpart //= $EMPTY;
+            my ($acceptonlyinfile,$applytag)
+              = split(/\s*\~\~\s*/, $secondpart, 2);
+
+            $acceptonlyinfile //= $EMPTY;
+            $applytag //= $EMPTY;
+
+            # trim both ends
+            $acceptonlyinfile =~ s/^\s+|\s+$//g;
+            $applytag =~ s/^\s+|\s+$//g;
+
+            # accept all files if empty
+            $acceptonlyinfile ||= $DOT . $ASTERISK;
+
+            my %ret = (
+                'gfdlsectionsregex'   => qr/$gfdlsectionsregex/xis,
+                'acceptonlyinfile' => qr/$acceptonlyinfile/xs,
+            );
+
+            $ret{'tag'} = $applytag
+              if length $applytag;
+
+            $gfdl_fragments{$gfdlsectionsregex} = \%ret;
+        }
+
+        return \%gfdl_fragments;
+    }
+);
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # license string in debian/changelog are probably just change
+    # Ignore these strings in d/README.{Debian,source}.  If they
+    # appear there it is probably just "file XXX got removed
+    # because of license Y".
+    $self->full_text_check($item)
+      unless $item->name eq 'debian/changelog'
+      && $item->name eq 'debian/README.Debian'
+      && $item->name eq 'debian/README.source';
+
+    return;
+}
+
+# do basic license check against well known offender
+# note that it does not replace licensecheck(1)
+# and is only used for autoreject by ftp-master
+sub full_text_check {
+    my ($self, $item) = @_;
+
+    return undef
+      unless $item ->is_regular_file;
+
+    open(my $fd, '<:raw', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $sfd = Lintian::SlidingWindow->new;
+    $sfd->handle($fd);
+    $sfd->blocksize(BLOCKSIZE);
+    $sfd->blocksub(sub { $_ = lc; });
+
+    unless (-T $fd) {
+        close($fd);
+        return undef;
+    }
+
+    # we try to read this file in block and use a sliding window
+    # for efficiency.  We store two blocks in @queue and the whole
+    # string to match in $block. Please emit license tags only once
+    # per file
+  BLOCK:
+    while (my $lowercase = $sfd->readwindow()) {
+
+        my $blocknumber = $sfd->blocknumber();
+
+        my $clean = clean_text($lowercase);
+
+        # Check for non-distributable files - this
+        # applies even to non-free, as we still need
+        # permission to distribute those.
+        # nvdia opencv infamous license
+        last BLOCK
+          if $self->check_for_single_bad_license($item, $lowercase, $clean,
+            'license-problem-nvidia-intellectual',
+            \%NVIDIA_LICENSE);
+
+        unless ($self->processable->is_non_free) {
+
+            for my $tag_name (keys %NON_FREE_LICENSES) {
+
+                last BLOCK
+                  if $self->check_for_single_bad_license($item, $lowercase,
+                    $clean,$tag_name, $NON_FREE_LICENSES{$tag_name});
+            }
+        }
+
+        # check javascript in html file
+        if ($item->basename =~ /\.(?:x?html?\d?|xht)$/i) {
+
+            my $blockscript = $lowercase;
+            my $indexscript;
+
+            while (($indexscript = index($blockscript, '<script'))
+                > $ITEM_NOT_FOUND){
+
+                $blockscript = substr($blockscript,$indexscript);
+
+                # sourced script ok
+                if ($blockscript =~ m{\A<script\s+[^>]*?src="[^"]+?"[^>]*?>}sm)
+                {
+
+                    $blockscript = substr($blockscript,$+[0]);
+                    next;
+                }
+
+                # extract script
+                if ($blockscript =~ m{<script[^>]*?>(.*?)</script>}sm) {
+
+                    $blockscript = substr($blockscript,$+[0]);
+
+                    my $lcscript = $1;
+
+                    # check if js script is minified
+                    my $firstline = $EMPTY;
+                    for my $line (split /\n/, $lcscript) {
+
+                        if ($line =~ /^\s*$/) {
+                            next;
+
+                        } else {
+                            $firstline = $line;
+                            last;
+                        }
+                    }
+
+                    if ($firstline
+                        =~ m/.{0,20}((?:\bcopyright\b|[\(]c[\)]\s*\w|\N{COPYRIGHT SIGN}).{0,50})/
+                    ){
+
+                        my $extract = $1;
+                        $extract =~ s/^\s+|\s+$//g;
+
+                        $self->pointed_hint(
+                            'embedded-script-includes-copyright-statement',
+                            $item->pointer,
+                            'extract of copyright statement:',
+                            $extract
+                        );
+                    }
+
+                    # clean up jslint craps line
+                    my $cleaned = $lcscript;
+                    $cleaned =~ s{^\s*/[*][^\n]*[*]/\s*$}{}gm;
+                    $cleaned =~ s{^\s*//[^\n]*$}{}gm;
+                    $cleaned =~ s/^\s+//gm;
+
+                    # strip indentation
+                    $cleaned =~ s/^\s+//mg;
+                    $cleaned = _strip_c_comments($cleaned);
+                    # strip empty line
+                    $cleaned =~ s/^\s*\n//mg;
+                    # remove last \n
+                    $cleaned =~ s/\n\Z//m;
+
+# detect browserified javascript (comment are removed here and code is stripped)
+                    my $contiguous = $cleaned;
+                    $contiguous =~ s/\n/ /msg;
+
+                    # get browserified regexp
+                    my $BROWSERIFY_REGEX
+                      = $self->data->load('cruft/browserify-regex',
+                        qr/\s*\~\~\s*/);
+
+                    for my $condition ($BROWSERIFY_REGEX->all) {
+
+                        my $pattern = $BROWSERIFY_REGEX->value($condition);
+                        if ($contiguous =~ m{$pattern}msx) {
+
+                            my $extra
+                              = (defined $1) ? 'code fragment:'.$1 : $EMPTY;
+                            $self->pointed_hint(
+                                'source-contains-browserified-javascript',
+                                $item->pointer, $extra);
+
+                            last;
+                        }
+                    }
+
+                    next;
+                }
+
+                last;
+            }
+        }
+
+        # check if file is javascript but not minified
+        my $isjsfile = ($item->name =~ m/\.js$/) ? 1 : 0;
+        if ($isjsfile) {
+            my $minjsregexp
+              = qr/(?i)[-._](?:compiled|compressed|lite|min|pack(?:ed)?|prod|umd|yc)\.js$/;
+            $isjsfile = ($item->name =~ m{$minjsregexp}) ? 0 : 1;
+        }
+
+        if ($isjsfile) {
+            # exception sphinx documentation
+            if ($item->basename eq 'searchindex.js') {
+                if ($lowercase =~ m/\A\s*search\.setindex\s* \s* \(\s*\{/xms) {
+
+                    $self->pointed_hint(
+                        'source-contains-prebuilt-sphinx-documentation',
+                        $item->parent_dir->pointer);
+                    last BLOCK;
+                }
+            }
+
+            if ($item->basename eq 'search_index.js') {
+                if ($lowercase =~ m/\A\s*var\s*search_index\s*=/xms) {
+
+                    $self->pointed_hint(
+                        'source-contains-prebuilt-pandoc-documentation',
+                        $item->parent_dir->pointer);
+                    last BLOCK;
+                }
+            }
+            # false positive in dx package at least
+            elsif ($item->basename eq 'srchidx.js') {
+
+                last BLOCK
+                  if $lowercase
+                  =~ m/\A\s*profiles \s* = \s* new \s* Array\s*\(/xms;
+            }
+            # https://github.com/rafaelp/css_browser_selector is actually the
+            # original source. (#874381)
+            elsif ($lowercase =~ m/css_browser_selector\(/) {
+
+                last BLOCK;
+            }
+        # Avoid false-positives in Jush's syntax highlighting definition files.
+            elsif ($lowercase =~ m/jush\.tr\./) {
+
+                last BLOCK;
+            }
+
+            # now search hidden minified
+
+            # clean up jslint craps line
+            my $cleaned = $lowercase;
+            $cleaned =~ s{^\s*/[*][^\n]*[*]/\s*$}{}gm;
+            $cleaned =~ s{^\s*//[^\n]*$}{}gm;
+            $cleaned =~ s/^\s+//gm;
+
+            # strip indentation
+            $cleaned =~ s/^\s+//mg;
+            $cleaned = _strip_c_comments($cleaned);
+            # strip empty line
+            $cleaned =~ s/^\s*\n//mg;
+            # remove last \n
+            $cleaned =~ s/\n\Z//m;
+
+# detect browserified javascript (comment are removed here and code is stripped)
+            my $contiguous = $cleaned;
+            $contiguous =~ s/\n/ /msg;
+
+            # get browserified regexp
+            my $BROWSERIFY_REGEX
+              = $self->data->load('cruft/browserify-regex',qr/\s*\~\~\s*/);
+
+            for my $condition ($BROWSERIFY_REGEX->all) {
+
+                my $pattern = $BROWSERIFY_REGEX->value($condition);
+                if ($contiguous =~ m{$pattern}msx) {
+
+                    my $extra = (defined $1) ? 'code fragment:'.$1 : $EMPTY;
+                    $self->pointed_hint(
+                        'source-contains-browserified-javascript',
+                        $item->pointer, $extra);
+
+                    last;
+                }
+            }
+        }
+
+        # search link rel header
+        if ($lowercase =~ / \Q rel="copyright" \E /msx) {
+
+            my $href = $lowercase;
+            $href =~ m{<link \s+
+                  rel="copyright" \s+
+                  href="([^"]+)" \s*/? \s*>}xmsi;
+
+            my $url = $1 // $EMPTY;
+
+            $self->pointed_hint('license-problem-cc-by-nc-sa', $item->pointer)
+              if $url =~ m{^https?://creativecommons.org/licenses/by-nc-sa/};
+        }
+        last BLOCK;
+    }
+    return close($fd);
+}
+
+# strip C comment
+# warning block is at more 8192 char in order to be too slow
+# and in order to avoid regex recursion
+sub _strip_c_comments {
+    my ($lowercase) = @_;
+
+    # from perl faq strip comments
+    $lowercase =~ s{
+                # Strip /* */ comments
+                /\* [^*]*+ \*++ (?: [^/*][^*]*+\*++ ) */
+                # Strip // comments (C++ style)
+                |  // (?: [^\\] | [^\n][\n]? )*? (?=\n)
+                |  (
+                    # Keep "/* */" (etc) as is
+                    "(?: \\. | [^"\\]++)*"
+                    # Keep '/**/' (etc) as is
+                    | '(?: \\. | [^'\\]++)*'
+                    # Keep anything else
+                    | .[^/"'\\]*+
+                   )
+               }{defined $1 ? $1 : ""}xgse;
+
+    return $lowercase;
+}
+
+# return True in case of license problem
+sub check_gfdl_license_problem {
+    my ($self, $item, $tag_name, %matchedhash) = @_;
+
+    my $rawgfdlsections  = $matchedhash{rawgfdlsections}  || $EMPTY;
+    my $rawcontextbefore = $matchedhash{rawcontextbefore} || $EMPTY;
+
+    # strip punctuation
+    my $gfdlsections  = _strip_punct($rawgfdlsections);
+    my $contextbefore = _strip_punct($rawcontextbefore);
+
+    # remove line number at beginning of line
+    # see krusader/1:2.4.0~beta3-2/doc/en_US/advanced-functions.docbook/
+    $gfdlsections =~ s{[ ]\d+[ ]}{ }gxsmo;
+    $gfdlsections =~ s{^\d+[ ]}{ }xsmo;
+    $gfdlsections =~ s{[ ]\d+$}{ }xsmo;
+    $gfdlsections =~ s{[ ]+}{ }xsmo;
+
+    # remove classical and without meaning part of
+    # matched string
+    my $oldgfdlsections;
+    do {
+        $oldgfdlsections = $gfdlsections;
+        $gfdlsections =~ s{ \A \(?[ ]? g?fdl [ ]?\)?[ ]? [,\.;]?[ ]?}{}xsmo;
+        $gfdlsections =~ s{ \A (?:either[ ])?
+                           version [ ] \d+(?:\.\d+)? [ ]?}{}xsmo;
+        $gfdlsections =~ s{ \A of [ ] the [ ] license [ ]?[,\.;][ ]?}{}xsmo;
+        $gfdlsections=~ s{ \A or (?:[ ]\(?[ ]? at [ ] your [ ] option [ ]?\)?)?
+                           [ ] any [ ] later [ ] version[ ]?}{}xsmo;
+        $gfdlsections =~ s{ \A (as[ ])? published [ ] by [ ]
+                           the [ ] free [ ] software [ ] foundation[ ]?}{}xsmo;
+        $gfdlsections =~ s{\(?[ ]? fsf [ ]?\)?[ ]?}{}xsmo;
+        $gfdlsections =~ s{\A [ ]? [,\.;]? [ ]?}{}xsmo;
+        $gfdlsections =~ s{[ ]? [,\.]? [ ]?\Z}{}xsmo;
+    } while ($oldgfdlsections ne $gfdlsections);
+
+    $contextbefore =~ s{
+                       [ ]? (:?[,\.;]? [ ]?)?
+                       permission [ ] is [ ] granted [ ] to [ ] copy [ ]?[,\.;]?[ ]?
+                       distribute [ ]?[,\.;]?[ ]? and[ ]?/?[ ]?or [ ] modify [ ]
+                       this [ ] document [ ] under [ ] the [ ] terms [ ] of [ ] the\Z}{}xsmo;
+
+    # Treat ambiguous empty text
+    if ($gfdlsections eq $EMPTY) {
+
+        # lie in order to check more part
+        $self->pointed_hint('license-problem-gfdl-invariants-empty',
+            $item->pointer);
+
+        return 0;
+    }
+
+    # official wording
+    if(
+        $gfdlsections =~ m{\A
+                          with [ ] no [ ] invariant [ ] sections[ ]?,
+                          [ ]? no [ ] front(?:[ ]?-[ ]?|[ ])cover [ ] texts[ ]?,?
+                          [ ]? and [ ] no [ ] back(?:[ ]?-?[ ]?|[ ])cover [ ] texts
+                          \Z}xs
+    ) {
+        return 0;
+    }
+
+    # example are ok
+    if (
+        $contextbefore =~ m{following [ ] is [ ] an [ ] example
+                           (:?[ ] of [ ] the [ ] license [ ] notice [ ] to [ ] use
+                            (?:[ ] after [ ] the [ ] copyright [ ] (?:line(?:\(s\)|s)?)?
+                             (?:[ ] using [ ] all [ ] the [ ] features? [ ] of [ ] the [ ] gfdl)?
+                            )?
+                           )? [ ]? [,:]? \Z}xs
+    ){
+        return 0;
+    }
+
+    # GFDL license, assume it is bad unless it
+    # explicitly states it has no "bad sections".
+    for my $gfdl_fragment (keys %{$self->GFDL_FRAGMENTS}) {
+
+        my $gfdl_data = $self->GFDL_FRAGMENTS->{$gfdl_fragment};
+        my $gfdlsectionsregex = $gfdl_data->{'gfdlsectionsregex'};
+        if ($gfdlsections =~ m{$gfdlsectionsregex}) {
+
+            my $acceptonlyinfile = $gfdl_data->{'acceptonlyinfile'};
+            if ($item->name =~ m{$acceptonlyinfile}) {
+
+                my $applytag = $gfdl_data->{'tag'};
+
+                # lie will allow checking more blocks
+                $self->pointed_hint($applytag, $item->pointer,
+                    'invariant part is:',
+                    $gfdlsections)
+                  if defined $applytag;
+
+                return 0;
+
+            } else {
+                $self->pointed_hint(
+                    'license-problem-gfdl-invariants',
+                    $item->pointer,'invariant part is:',
+                    $gfdlsections
+                );
+                return 1;
+            }
+        }
+    }
+
+    # catch all
+    $self->pointed_hint(
+        'license-problem-gfdl-invariants',
+        $item->pointer,'invariant part is:',
+        $gfdlsections
+    );
+
+    return 1;
+}
+
+sub rfc_whitelist_filename {
+    my ($self, $item, $tag_name, %matchedhash) = @_;
+
+    return 0
+      if $item->name eq 'debian/copyright';
+
+    my $lcname = lc($item->basename);
+
+    # prebuilt-file or forbidden file type
+    # specified separator protects against spaces in pattern
+    my $RFC_WHITELIST= $self->data->load('cruft/rfc-whitelist',qr/\s*\~\~\s*/);
+
+    my @patterns = $RFC_WHITELIST->all;
+
+    return 0
+      if any { $lcname =~ m/ $_ /xms } @patterns;
+
+    $self->pointed_hint($tag_name, $item->pointer);
+
+    return 1;
+}
+
+sub php_source_whitelist {
+    my ($self, $item, $tag_name, %matchedhash) = @_;
+
+    my $copyright_path
+      = $self->processable->patched->resolve_path('debian/copyright');
+
+    return 0
+      if defined $copyright_path
+      && $copyright_path->bytes
+      =~ m{^Source: https?://(pecl|pear).php.net/package/.*$}m;
+
+    return 0
+      if $self->processable->source_name =~ /^php\d*(?:\.\d+)?$/xms;
+
+    $self->pointed_hint($tag_name, $item->pointer);
+
+    return 1;
+}
+
+sub clean_text {
+    my ($text) = @_;
+
+    # be paranoiac replace gnu with texinfo by gnu
+    $text =~ s{
+                 (?:@[[:alpha:]]*?\{)?\s*gnu\s*\}                   # Texinfo cmd
+             }{ gnu }gxms;
+
+    # pod2man formatting
+    $text =~ s{ \\ \* \( [LR] \" }{\"}gxsm;
+    $text =~ s{ \\ -}{-}gxsm;
+
+    # replace some shortcut (clisp)
+    $text =~ s{\(&fdl;\)}{ }gxsm;
+    $text =~ s{&fsf;}{free software foundation}gxsm;
+
+    # non breaking space
+    $text =~ s{&nbsp;}{ }gxsm;
+
+    # replace some common comment-marker/markup with space
+    $text =~ s{^\.\\\"}{ }gxms;               # man comments
+
+    # po comment may include html tag
+    $text =~ s/\"\s?\v\#~\s?\"//gxms;
+
+    # strip .rtf paragraph marks (#892967)
+    $text =~ s/\\par\b//gxms;
+
+    $text =~ s/\\url[{][^}]*?[}]/ /gxms;      # (la)?tex url
+    $text =~ s/\\emph[{]/ /gxms;              # (la)?tex emph
+    $text =~ s<\\href[{][^}]*?[}]
+                     [{]([^}]*?)[}]>< $1 >gxms;# (la)?tex href
+    $text =~ s<\\hyperlink
+                 [{][^}]*?[}]
+                 [{]([^}]*?)[}]>< $1 >gxms;    # (la)?tex hyperlink
+    $text =~ s{-\\/}{-}gxms;                   # tex strange hyphen
+    $text =~ s/\\char/ /gxms;                 # tex  char command
+
+    # Texinfo comment with end section
+    $text =~ s{\@c(?:omment)?\h+
+                end \h+ ifman\s+}{ }gxms;
+    $text =~ s{\@c(?:omment)?\s+
+                noman\s+}{ }gxms;              # Texinfo comment no manual
+
+    $text =~ s/\@c(?:omment)?\s+/ /gxms;      # Texinfo comment
+
+    # Texinfo bold,italic, roman, fixed width
+    $text =~ s/\@[birt][{]/ /gxms;
+    $text =~ s/\@sansserif[{]/ /gxms;         # Texinfo sans serif
+    $text =~ s/\@slanted[{]/ /gxms;             # Texinfo slanted
+    $text =~ s/\@var[{]/ /gxms;                 # Texinfo emphasis
+
+    $text =~ s/\@(?:small)?example\s+/ /gxms; # Texinfo example
+    $text =~ s{\@end \h+
+               (?:small)example\s+}{ }gxms;    # Texinfo end example tag
+    $text =~ s/\@group\s+/ /gxms;             # Texinfo group
+    $text =~ s/\@end\h+group\s+/ /gxms;       # Texinfo end group
+
+    $text =~ s/<!--/ /gxms;                   # XML comments
+    $text =~ s/-->/ /gxms;                    # end XML comment
+
+    $text =~ s{</?a[^>]*?>}{ }gxms;           # a link
+    $text =~ s{<br\s*/?>}{ }gxms;             # (X)?HTML line
+     # breaks
+    $text =~ s{</?citetitle[^>]*?>}{ }gxms;   # DocBook citation title
+    $text =~ s{</?div[^>]*?>}{ }gxms;         # html style
+    $text =~ s{</?font[^>]*?>}{ }gxms;        # bold
+    $text =~ s{</?b[^>]*?>}{ }gxms;           # italic
+    $text =~ s{</?i[^>]*?>}{ }gxms;           # italic
+    $text =~ s{</?link[^>]*?>}{ }gxms;        # xml link
+    $text =~ s{</?p[^>]*?>}{ }gxms;           # html paragraph
+    $text =~ s{</?quote[^>]*?>}{ }gxms;       # xml quote
+    $text =~ s{</?span[^>]*?>}{ }gxms;        # span tag
+    $text =~ s{</?ulink[^>]*?>}{ }gxms;       # ulink DocBook
+    $text =~ s{</?var[^>]*?>}{ }gxms;         # var used by texinfo2html
+
+    $text =~ s{\&[lr]dquo;}{ }gxms;           # html rquote
+
+    $text =~ s{\(\*note.*?::\)}{ }gxms;       # info file note
+
+    # String array (e.g. "line1",\n"line2")
+    $text =~ s/\"\s*,/ /gxms;
+    # String array (e.g. "line1"\n ,"line2"),
+    $text =~ s/,\s*\"/ /gxms;
+    $text =~ s/\\n/ /gxms;                    # Verbatim \n in string array
+
+    $text =~ s/\\&/ /gxms;                    # pod2man formatting
+    $text =~ s/\\s(?:0|-1)/ /gxms;            # pod2man formatting
+
+    $text =~ s/(?:``|'')/ /gxms;              # quote like
+
+    # diff/patch lines (should be after html tag)
+    $text =~ s/^[-\+!<>]/ /gxms;
+    $text =~ s{\@\@ \s*
+               [-+] \d+,\d+ \s+
+               [-+] \d+,\d+ \s*
+               \@\@}{ }gxms;                   # patch line
+
+    # Texinfo end tag (could be more clever but brute force is fast)
+    $text =~ s/}/ /gxms;
+    # Tex section titles
+    $text =~ s/^\s*\\(sub)*section\*?\{\s*\S+/ /gxms;
+    # single char at end
+    # String, C-style comment/javadoc indent,
+    # quotes for strings, pipe and backslash, tilde in some txt
+    $text =~ s/[%\*\"\|\\\#~]/ /gxms;
+    # delete double spacing now and normalize spacing
+    # to space character
+    $text =~ s{\s++}{ }gsm;
+
+    # trim both ends
+    $text =~ s/^\s+|\s+$//g;
+
+    return $text;
+}
+
+# do not use space around punctuation
+sub _strip_punct() {
+    my ($text) = @_;
+    # replace final punctuation
+    $text =~ s{(?:
+        \s*[,\.;]\s*\Z               |  # final punctuation
+        \A\s*[,\.;]\s*                  # punctuation at the beginning
+    )}{ }gxms;
+
+    # delete double spacing now and normalize spacing
+    # to space character
+    $text =~ s{\s++}{ }gsm;
+
+    # trim both ends
+    $text =~ s/^\s+|\s+$//g;
+
+    return $text;
+}
+
+sub check_for_single_bad_license {
+    my ($self, $item, $lowercase, $clean, $tag_name, $license_data) = @_;
+
+    # do fast keyword search
+    # could make more sense as 'return 1 unless all' but does not work
+    return 0
+      if none { $lowercase =~ / \Q$_\E /msx } @{$license_data->{keywords}};
+
+    return 0
+      if none { $clean =~ / \Q$_\E /msx }@{$license_data->{sentences}};
+
+    my $regex = $license_data->{regex};
+    return 0
+      if defined $regex && $clean !~ $regex;
+
+    my $callsub = $license_data->{callsub};
+    if (!defined $callsub) {
+
+        $self->pointed_hint($tag_name, $item->pointer);
+        return 1;
+    }
+
+    return $self->$callsub($item, $tag_name, %+);
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/DebFormat.pm b/lib/Lintian/Check/DebFormat.pm
new file mode 100644
index 0000000..57c57a4
--- /dev/null
+++ b/lib/Lintian/Check/DebFormat.pm
@@ -0,0 +1,227 @@
+# deb-format -- lintian check script -*- perl -*-
+
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2018 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Check::DebFormat;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use IPC::Run3;
+use List::SomeUtils qw(first_index none);
+use Path::Tiny;
+use Unicode::UTF8 qw(decode_utf8);
+
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SPACE => q{ };
+
+const my $MINIMUM_DEB_ARCHIVE_MEMBERS => 3;
+const my $INDEX_NOT_FOUND => -1;
+
+sub installable {
+    my ($self) = @_;
+
+    my $EXTRA_MEMBERS = $self->data->load('deb-format/extra-members');
+
+    my $deb_path = $self->processable->path;
+
+    # set to one when something is so bad that we can't continue
+    my $failed;
+
+    my @command = ('ar', 't', $deb_path);
+
+    my $stdout;
+    my $stderr;
+
+    run3(\@command, \undef, \$stdout, \$stderr);
+
+    unless ($?) {
+        my @members = split(/\n/, $stdout);
+        my $count = scalar(@members);
+        my ($ctrl_member, $data_member);
+
+        if ($count < $MINIMUM_DEB_ARCHIVE_MEMBERS) {
+            $self->hint('malformed-deb-archive',
+"found only $count members instead of $MINIMUM_DEB_ARCHIVE_MEMBERS"
+            );
+
+        } elsif ($members[0] ne 'debian-binary') {
+            $self->hint('malformed-deb-archive',
+                "first member $members[0] not debian-binary");
+
+        } elsif ($count == $MINIMUM_DEB_ARCHIVE_MEMBERS
+            && none {substr($_, 0, 1) eq '_';}@members) {
+            # Fairly common case - if there are only 3 members without
+            # "_", we can trivially determine their (expected)
+            # positions.  We only use this case when there are no
+            # "extra" members, because they can trigger more tags
+            # (see below)
+            (undef, $ctrl_member, $data_member) = @members;
+
+        } else {
+            my $ctrl_index
+              = first_index { substr($_, 0, 1) ne '_' } @members[1..$#members];
+            my $data_index;
+
+            if ($ctrl_index != $INDEX_NOT_FOUND) {
+                # Since we searched only a sublist of @members, we have to
+                # add 1 to $ctrl_index
+                $ctrl_index++;
+                $ctrl_member = $members[$ctrl_index];
+                $data_index = first_index { substr($_, 0, 1) ne '_' }
+                @members[$ctrl_index+1..$#members];
+                if ($data_index != $INDEX_NOT_FOUND) {
+                    # Since we searched only a sublist of @members, we
+                    # have to adjust $data_index
+                    $data_index += $ctrl_index + 1;
+                    $data_member = $members[$data_index];
+                }
+            }
+
+            # Extra members
+            # NB: We deliberately do not allow _extra member,
+            # since various tools seems to be unable to cope
+            # with them particularly dak
+            # see https://wiki.debian.org/Teams/Dpkg/DebSupport
+            for my $i (1..$#members) {
+                my $member = $members[$i];
+                my $actual_index = $i;
+                my ($expected, $text);
+                next if $i == $ctrl_index or $i == $data_index;
+                $expected = $EXTRA_MEMBERS->value($member);
+                if (defined($expected)) {
+                    next if $expected eq 'ANYWHERE';
+                    next if $expected == $actual_index;
+                    $text = "expected at position $expected, but appeared";
+                } elsif (substr($member,0,1) eq '_') {
+                    $text = 'unexpected _member';
+                } else {
+                    $text = 'unexpected member';
+                }
+                $self->hint('misplaced-extra-member-in-deb',
+                    "$member ($text at position $actual_index)");
+            }
+        }
+
+        if (not defined($ctrl_member)) {
+            # Somehow I doubt we will ever get this far without a control
+            # file... :)
+            $self->hint('malformed-deb-archive', 'Missing control.tar member');
+            $failed = 1;
+        } else {
+            if (
+                $ctrl_member !~ m{\A
+                     control\.tar(?:\.(?:gz|xz))?  \Z}xsm
+            ) {
+                $self->hint(
+                    'malformed-deb-archive',
+                    join($SPACE,
+                        "second (official) member $ctrl_member",
+                        'not control.tar.(gz|xz)')
+                );
+                $failed = 1;
+            } elsif ($ctrl_member eq 'control.tar') {
+                $self->hint('uses-no-compression-for-control-tarball');
+            }
+            $self->hint('control-tarball-compression-format',
+                $ctrl_member =~ s/^control\.tar\.?//r || '(none)');
+        }
+
+        if (not defined($data_member)) {
+            # Somehow I doubt we will ever get this far without a data
+            # member (i.e. I suspect unpacked and index will fail), but
+            # mah
+            $self->hint('malformed-deb-archive', 'Missing data.tar member');
+            $failed = 1;
+        } else {
+            if (
+                $data_member !~ m{\A
+                     data\.tar(?:\.(?:gz|bz2|xz|lzma))?  \Z}xsm
+            ) {
+                # wasn't okay after all
+                $self->hint(
+                    'malformed-deb-archive',
+                    join($SPACE,
+                        "third (official) member $data_member",
+                        'not data.tar.(gz|xz|bz2|lzma)')
+                );
+                $failed = 1;
+            } elsif ($self->processable->type eq 'udeb'
+                && $data_member !~ m/^data\.tar\.[gx]z$/) {
+                $self->hint(
+                    'udeb-uses-unsupported-compression-for-data-tarball');
+            } elsif ($data_member eq 'data.tar.lzma') {
+                $self->hint('uses-deprecated-compression-for-data-tarball',
+                    'lzma');
+                # Ubuntu's archive allows lzma packages.
+                $self->hint('lzma-deb-archive');
+            } elsif ($data_member eq 'data.tar.bz2') {
+                $self->hint('uses-deprecated-compression-for-data-tarball',
+                    'bzip2');
+            } elsif ($data_member eq 'data.tar') {
+                $self->hint('uses-no-compression-for-data-tarball');
+            }
+            $self->hint('data-tarball-compression-format',
+                $data_member =~ s/^data\.tar\.?//r || '(none)');
+        }
+    } else {
+        # unpack will probably fail so we'll never get here, but may as well be
+        # complete just in case.
+        $stderr =~ s/\n.*//s;
+        $stderr =~ s/^ar:\s*//;
+        $stderr =~ s/^deb:\s*//;
+        $self->hint('malformed-deb-archive', "ar error: $stderr");
+    }
+
+    # Check the debian-binary version number.  We probably won't get
+    # here because dpkg-deb will decline to unpack the deb, but be
+    # thorough just in case.  We may eventually have a case where dpkg
+    # supports a newer format but it's not permitted in the archive
+    # yet.
+    if (not defined($failed)) {
+        my $bytes = safe_qx('ar', 'p', $deb_path, 'debian-binary');
+        if ($? != 0) {
+            $self->hint('malformed-deb-archive',
+                'cannot read debian-binary member');
+        } else {
+            my $output = decode_utf8($bytes);
+            if ($output !~ /^2\.\d+\n/) {
+                my ($version) = split(m/\n/, $output);
+                $self->hint('malformed-deb-archive',
+                    "version $version not 2.0");
+            }
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debhelper.pm b/lib/Lintian/Check/Debhelper.pm
new file mode 100644
index 0000000..b2cee04
--- /dev/null
+++ b/lib/Lintian/Check/Debhelper.pm
@@ -0,0 +1,1088 @@
+# debhelper format -- lintian check script -*- perl -*-
+
+# Copyright (C) 1999 by Joey Hess
+# Copyright (C) 2016-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debhelper;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::Compare;
+use List::SomeUtils qw(any firstval);
+use List::UtilsBy qw(min_by);
+use Text::LevenshteinXS qw(distance);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Relation;
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $DOLLAR => q{$};
+const my $UNDERSCORE => q{_};
+const my $HORIZONTAL_BAR => q{|};
+
+const my $ARROW => q{=>};
+
+# If there is no debian/compat file present but cdbs is being used, cdbs will
+# create one automatically.  Currently it always uses compatibility level 5.
+# It may be better to look at what version of cdbs the package depends on and
+# from that derive the compatibility level....
+const my $CDBS_COMPAT => 5;
+
+# minimum versions for features
+const my $BRACE_EXPANSION => 5;
+const my $USES_EXECUTABLE_FILES => 9;
+const my $DH_PARALLEL_NOT_NEEDED => 10;
+const my $REQUIRES_AUTOTOOLS => 10;
+const my $USES_AUTORECONF => 10;
+const my $INVOKES_SYSTEMD => 10;
+const my $BETTER_SYSTEMD_INTEGRATION => 11;
+const my $VERSIONED_PREREQUISITE_AVAILABLE => 11;
+
+const my $LEVENSHTEIN_TOLERANCE => 3;
+const my $MANY_OVERRIDES => 20;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+my $MISC_DEPENDS = Lintian::Relation->new->load($DOLLAR . '{misc:Depends}');
+
+# Manually maintained list of dh_commands that requires a versioned
+# dependency *AND* are not provided by debhelper.  Commands provided
+# by debhelper is handled in checks/debhelper.
+#
+# This overrules any thing listed in dh_commands (which is auto-generated).
+
+my %DH_COMMAND_MANUAL_PREREQUISITES = (
+    dh_apache2 => 'dh-apache2:any | apache2-dev:any',
+    dh_autoreconf_clean =>
+'dh-autoreconf:any | debhelper:any (>= 9.20160403~) | debhelper-compat:any',
+    dh_autoreconf =>
+'dh-autoreconf:any | debhelper:any (>= 9.20160403~) | debhelper-compat:any',
+    dh_dkms => 'dh-dkms:any | dh-sequence-dkms:any',
+    dh_girepository => 'gobject-introspection:any | dh-sequence-gir:any',
+    dh_gnome => 'gnome-pkg-tools:any | dh-sequence-gnome:any',
+    dh_gnome_clean => 'gnome-pkg-tools:any | dh-sequence-gnome:any',
+    dh_lv2config => 'lv2core:any',
+    dh_make_pgxs => 'postgresql-server-dev-all:any | postgresql-all:any',
+    dh_nativejava => 'gcj-native-helper:any | default-jdk-builddep:any',
+    dh_pgxs_test => 'postgresql-server-dev-all:any | postgresql-all:any',
+    dh_python2 => 'dh-python:any | dh-sequence-python2:any',
+    dh_python3 =>
+      'dh-python:any | dh-sequence-python3:any | pybuild-plugin-pyproject:any',
+    dh_sphinxdoc =>
+'sphinx:any | python-sphinx:any | python3-sphinx:any | dh-sequence-sphinxdoc:any',
+    dh_xine => 'libxine-dev:any | libxine2-dev:any'
+);
+
+# Manually maintained list of dependencies needed for dh addons. This overrides
+# information from data/common/dh_addons (the latter file is automatically
+# generated).
+my %DH_ADDON_MANUAL_PREREQUISITES = (
+    ada_library => 'dh-ada-library:any | dh-sequence-ada-library:any',
+    apache2 => 'dh-apache2:any | apache2-dev:any',
+    autoreconf =>
+'dh-autoreconf:any | debhelper:any (>= 9.20160403~) | debhelper-compat:any',
+    cli => 'cli-common-dev:any | dh-sequence-cli:any',
+    dwz => 'debhelper:any | debhelper-compat:any | dh-sequence-dwz:any',
+    installinitramfs =>
+'debhelper:any | debhelper-compat:any | dh-sequence-installinitramfs:any',
+    gnome => 'gnome-pkg-tools:any | dh-sequence-gnome:any',
+    lv2config => 'lv2core:any',
+    nodejs => 'pkg-js-tools:any | dh-sequence-nodejs:any',
+    perl_dbi => 'libdbi-perl:any | dh-sequence-perl-dbi:any',
+    perl_imager => 'libimager-perl:any | dh-sequence-perl-imager:any',
+    pgxs => 'postgresql-server-dev-all:any | postgresql-all:any',
+    pgxs_loop => 'postgresql-server-dev-all:any | postgresql-all:any',
+    pypy => 'dh-python:any | dh-sequence-pypy:any',
+    python2 => 'python2:any | python2-dev:any | dh-sequence-python2:any',
+    python3 =>
+'python3:any | python3-all:any | python3-dev:any | python3-all-dev:any | dh-sequence-python3:any',
+    scour => 'scour:any | python-scour:any | dh-sequence-scour:any',
+    sphinxdoc =>
+'sphinx:any | python-sphinx:any | python3-sphinx:any | dh-sequence-sphinxdoc:any',
+    systemd =>
+'debhelper:any (>= 9.20160709~) | debhelper-compat:any | dh-sequence-systemd:any | dh-systemd:any',
+    vim_addon => 'dh-vim-addon:any | dh-sequence-vim-addon:any',
+);
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->dirname eq 'debian/';
+
+    return
+      if !$item->is_symlink && !$item->is_file;
+
+    if (   $item->basename eq 'control'
+        || $item->basename =~ m/^(?:.*\.)?(?:copyright|changelog|NEWS)$/) {
+
+        # Handle "control", [<pkg>.]copyright, [<pkg>.]changelog
+        # and [<pkg>.]NEWS
+
+        # The permissions of symlinks are not really defined, so resolve
+        # $item to ensure we are not dealing with a symlink.
+        my $actual = $item->resolve_path;
+
+        $self->pointed_hint('package-file-is-executable', $item->pointer)
+          if $actual && $actual->is_executable;
+
+        return;
+    }
+
+    return;
+}
+
+sub source {
+    my ($self) = @_;
+
+    my @MAINT_COMMANDS = @{$self->data->debhelper_commands->maint_commands};
+
+    my $FILENAME_CONFIGS= $self->data->load('debhelper/filename-config-files');
+
+    my $DEBHELPER_LEVELS = $self->data->debhelper_levels;
+    my $DH_ADDONS = $self->data->debhelper_addons;
+    my $DH_COMMANDS_DEPENDS= $self->data->debhelper_commands;
+
+    my @KNOWN_DH_COMMANDS;
+    for my $command ($DH_COMMANDS_DEPENDS->all) {
+        for my $focus ($EMPTY, qw(-arch -indep)) {
+            for my $timing (qw(override execute_before execute_after)) {
+
+                push(@KNOWN_DH_COMMANDS,
+                    $timing . $UNDERSCORE . $command . $focus);
+            }
+        }
+    }
+
+    my $debhelper_level;
+    my $dh_compat_variable;
+    my $maybe_skipping;
+
+    my $uses_debhelper = 0;
+    my $uses_dh_exec = 0;
+    my $uses_autotools_dev_dh = 0;
+
+    my $includes_cdbs = 0;
+    my $modifies_scripts = 0;
+
+    my $seen_any_dh_command = 0;
+    my $seen_dh_sequencer = 0;
+    my $seen_dh_dynamic = 0;
+    my $seen_dh_systemd = 0;
+    my $seen_dh_parallel = 0;
+    my $seen_dh_clean_k = 0;
+
+    my %command_by_prerequisite;
+    my %addon_by_prerequisite;
+    my %overrides;
+
+    my $droot = $self->processable->patched->resolve_path('debian/');
+
+    my $drules;
+    $drules = $droot->child('rules') if $droot;
+
+    return
+      unless $drules && $drules->is_open_ok;
+
+    open(my $rules_fd, '<', $drules->unpacked_path)
+      or die encode_utf8('Cannot open ' . $drules->unpacked_path);
+
+    my $command_prefix_pattern = qr/\s+[@+-]?(?:\S+=\S+\s+)*/;
+
+    my $build_prerequisites_norestriction
+      = $self->processable->relation_norestriction('Build-Depends-All');
+    my $build_prerequisites= $self->processable->relation('Build-Depends-All');
+
+    my %seen = (
+        'python2' => 0,
+        'python3' => 0,
+        'runit'   => 0,
+        'sphinxdoc' => 0,
+    );
+
+    for (qw(python2 python3)) {
+
+        $seen{$_} = 1
+          if $build_prerequisites_norestriction->satisfies(
+            "dh-sequence-$_:any");
+    }
+
+    my %build_systems;
+
+    my $position = 1;
+    while (my $line = <$rules_fd>) {
+
+        my $pointer = $drules->pointer($position);
+
+        while ($line =~ s/\\$// && defined(my $cont = <$rules_fd>)) {
+            $line .= $cont;
+        }
+
+        if ($line =~ /^ifn?(?:eq|def)\s/) {
+            $maybe_skipping++;
+
+        } elsif ($line =~ /^endif\s/) {
+            $maybe_skipping--;
+        }
+
+        next
+          if $line =~ /^\s*\#/;
+
+        if ($line =~ /^$command_prefix_pattern(dh_(?!autoreconf)\S+)/) {
+
+            my $dh_command = $1;
+
+            $build_systems{'debhelper'} = 1
+              unless exists $build_systems{'dh'};
+
+            $self->pointed_hint('dh_installmanpages-is-obsolete',$pointer)
+              if $dh_command eq 'dh_installmanpages';
+
+            if (   $dh_command eq 'dh_autotools-dev_restoreconfig'
+                || $dh_command eq 'dh_autotools-dev_updateconfig') {
+
+                $self->pointed_hint(
+                    'debhelper-tools-from-autotools-dev-are-deprecated',
+                    $pointer, $dh_command);
+                $uses_autotools_dev_dh = 1;
+            }
+
+            # Record if we've seen specific helpers, special-casing
+            # "dh_python" as Python 2.x.
+            $seen{'python2'} = 1 if $dh_command eq 'dh_python2';
+            for my $k (keys %seen) {
+                $seen{$k} = 1 if $dh_command eq "dh_$k";
+            }
+
+            $seen_dh_clean_k = 1
+              if $dh_command eq 'dh_clean'
+              && $line =~ /\s+\-k(?:\s+.*)?$/s;
+
+            # if command is passed -n, it does not modify the scripts
+            $modifies_scripts = 1
+              if (any { $dh_command eq $_ } @MAINT_COMMANDS)
+              && $line !~ /\s+\-n\s+/;
+
+           # If debhelper commands are wrapped in make conditionals, assume the
+           # maintainer knows what they're doing and don't check build
+           # dependencies.
+            unless ($maybe_skipping) {
+
+                if (exists $DH_COMMAND_MANUAL_PREREQUISITES{$dh_command}) {
+                    my $prerequisite
+                      = $DH_COMMAND_MANUAL_PREREQUISITES{$dh_command};
+                    $command_by_prerequisite{$prerequisite} = $dh_command;
+
+                } elsif ($DH_COMMANDS_DEPENDS->installed_by($dh_command)) {
+
+                    my @broadened = map { "$_:any" }
+                      $DH_COMMANDS_DEPENDS->installed_by($dh_command);
+                    my $prerequisite
+                      = join($SPACE . $HORIZONTAL_BAR . $SPACE,@broadened);
+                    $command_by_prerequisite{$prerequisite} = $dh_command;
+                }
+            }
+
+            $seen_any_dh_command = 1;
+            $uses_debhelper = 1;
+
+        } elsif ($line =~ m{^(?:$command_prefix_pattern)dh\s+}) {
+
+            $build_systems{'dh'} = 1;
+            delete($build_systems{'debhelper'});
+
+            $seen_dh_sequencer = 1;
+            $seen_any_dh_command = 1;
+
+            $seen_dh_dynamic = 1
+              if $line =~ /\$[({]\w/;
+
+            $seen_dh_parallel = $position
+              if $line =~ /--parallel/;
+
+            $uses_debhelper = 1;
+            $modifies_scripts = 1;
+
+            while ($line =~ /\s--with(?:=|\s+)(['"]?)(\S+)\1/g) {
+
+                my $addon_list = $2;
+
+                for my $addon (split(/,/, $addon_list)) {
+
+                    my $orig_addon = $addon;
+
+                    $addon =~ y,-,_,;
+
+                    my @broadened
+                      = map { "$_:any" } $DH_ADDONS->installed_by($addon);
+                    my $prerequisite = $DH_ADDON_MANUAL_PREREQUISITES{$addon}
+                      || join($SPACE . $HORIZONTAL_BAR . $SPACE,@broadened);
+
+                    if ($addon eq 'autotools_dev') {
+
+                        $self->pointed_hint(
+'debhelper-tools-from-autotools-dev-are-deprecated',
+                            $pointer,"dh ... --with $orig_addon"
+                        );
+                        $uses_autotools_dev_dh = 1;
+                    }
+
+                    $seen_dh_systemd = $position
+                      if $addon eq 'systemd';
+
+                    $self->pointed_hint(
+                        'dh-quilt-addon-but-quilt-source-format',
+                        $pointer,"dh ... --with $orig_addon")
+                      if $addon eq 'quilt'
+                      && $self->processable->fields->value('Format') eq
+                      '3.0 (quilt)';
+
+                    $addon_by_prerequisite{$prerequisite} = $addon
+                      if defined $prerequisite;
+
+                    for my $k (keys %seen) {
+                        $seen{$k} = 1
+                          if $addon eq $k;
+                    }
+                }
+            }
+
+        } elsif ($line =~ m{^include\s+/usr/share/cdbs/1/rules/debhelper.mk}
+            || $line =~ m{^include\s+/usr/share/R/debian/r-cran.mk}) {
+
+            $build_systems{'cdbs-with-debhelper.mk'} = 1;
+            delete($build_systems{'cdbs-without-debhelper.mk'});
+
+            $seen_any_dh_command = 1;
+            $uses_debhelper = 1;
+            $modifies_scripts = 1;
+            $includes_cdbs = 1;
+
+            # CDBS sets DH_COMPAT but doesn't export it.
+            $dh_compat_variable = $CDBS_COMPAT;
+
+        } elsif ($line =~ /^\s*export\s+DH_COMPAT\s*:?=\s*([^\s]+)/) {
+            $debhelper_level = $1;
+
+        } elsif ($line =~ /^\s*export\s+DH_COMPAT/) {
+            $debhelper_level = $dh_compat_variable
+              if $dh_compat_variable;
+
+        } elsif ($line =~ /^\s*DH_COMPAT\s*:?=\s*([^\s]+)/) {
+            $dh_compat_variable = $1;
+
+            # one can export and then set the value:
+            $debhelper_level = $1
+              if $debhelper_level;
+
+        } elsif (
+            $line =~ /^[^:]*(override|execute_(?:after|before))\s+(dh_[^:]*):/)
+        {
+            $self->pointed_hint('typo-in-debhelper-override-target',
+                $pointer, "$1 $2",$ARROW, "$1_$2");
+
+        } elsif ($line =~ /^([^:]*_dh_[^:]*):/) {
+
+            my $alltargets = $1;
+            # can be multiple targets per rule.
+            my @targets = split(/\s+/, $alltargets);
+            my @dh_targets = grep { /_dh_/ } @targets;
+
+            # If maintainer is using wildcards, it's unlikely to be a typo.
+            my @no_wildcards = grep { !/%/ } @dh_targets;
+
+            my $lc = List::Compare->new(\@no_wildcards, \@KNOWN_DH_COMMANDS);
+            my @unknown = $lc->get_Lonly;
+
+            for my $target (@unknown) {
+
+                my %distance
+                  = map { $_ => distance($target, $_) } @KNOWN_DH_COMMANDS;
+                my @near = grep { $distance{$_} < $LEVENSHTEIN_TOLERANCE }
+                  keys %distance;
+                my $nearest = min_by { $distance{$_} } @near;
+
+                $self->pointed_hint('typo-in-debhelper-override-target',
+                    $pointer, $target, $ARROW, $nearest)
+                  if length $nearest;
+            }
+
+            for my $target (@no_wildcards) {
+
+                next
+                  unless $target
+                  =~ /^(override|execute_(?:before|after))_dh_([^\s]+?)(-arch|-indep|)$/;
+
+                my $timing = $1;
+                my $command = $2;
+                my $focus = $3;
+                my $dh_command = "dh_$command";
+
+                $overrides{$dh_command} = [$position, $focus];
+                $uses_debhelper = 1;
+
+                next
+                  if $DH_COMMANDS_DEPENDS->installed_by($dh_command);
+
+                # Unknown command, so check for likely misspellings
+                my $missingauto = firstval { "dh_auto_$command" eq $_ }
+                $DH_COMMANDS_DEPENDS->all;
+
+                $self->pointed_hint(
+                    'typo-in-debhelper-override-target',$pointer,
+                    $timing . $UNDERSCORE . $dh_command,$ARROW,
+                    $timing . $UNDERSCORE . $missingauto,
+                )if length $missingauto;
+            }
+
+        } elsif ($line =~ m{^include\s+/usr/share/cdbs/}) {
+
+            $includes_cdbs = 1;
+
+            $build_systems{'cdbs-without-debhelper.mk'} = 1
+              unless exists $build_systems{'cdbs-with-debhelper.mk'};
+
+        } elsif (
+            $line =~m{
+              ^include \s+
+                 /usr/share/(?:
+                   dh-php/pkg-pecl\.mk
+                  |blends-dev/rules
+                 )
+              }xsm
+        ) {
+            # All of these indirectly use dh.
+            $seen_any_dh_command = 1;
+            $build_systems{'dh'} = 1;
+            delete($build_systems{'debhelper'});
+
+        } elsif (
+            $line =~m{
+              ^include \s+
+                 /usr/share/pkg-kde-tools/qt-kde-team/\d+/debian-qt-kde\.mk
+              }xsm
+        ) {
+
+            $includes_cdbs = 1;
+            $build_systems{'dhmk'} = 1;
+            delete($build_systems{'debhelper'});
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    close $rules_fd;
+
+    # Variables could contain any add-ons; assume we have seen them all
+    %seen = map { $_ => 1 } keys %seen
+      if $seen_dh_dynamic;
+
+    # Okay - d/rules does not include any file in /usr/share/cdbs/
+    $self->pointed_hint('unused-build-dependency-on-cdbs', $drules->pointer)
+      if $build_prerequisites->satisfies('cdbs:any')
+      && !$includes_cdbs;
+
+    if (%build_systems) {
+
+        my @systems = sort keys %build_systems;
+        $self->pointed_hint('debian-build-system', $drules->pointer,
+            join(', ', @systems));
+
+    } else {
+        $self->pointed_hint('debian-build-system', $drules->pointer, 'other');
+    }
+
+    unless ($seen_any_dh_command || $includes_cdbs) {
+
+        $self->pointed_hint('package-does-not-use-debhelper-or-cdbs',
+            $drules->pointer);
+        return;
+    }
+
+    my @installable_names= $self->processable->debian_control->installables;
+
+    for my $installable_name (@installable_names) {
+
+        next
+          if $self->processable->debian_control->installable_package_type(
+            $installable_name) ne 'deb';
+
+        my $strong
+          = $self->processable->binary_relation($installable_name, 'strong');
+        my $all= $self->processable->binary_relation($installable_name, 'all');
+
+        $self->hint('debhelper-but-no-misc-depends', $installable_name)
+          unless $all->satisfies($MISC_DEPENDS);
+
+        $self->hint('weak-dependency-on-misc-depends', $installable_name)
+          if $all->satisfies($MISC_DEPENDS)
+          && !$strong->satisfies($MISC_DEPENDS);
+    }
+
+    for my $installable ($self->group->get_installables) {
+
+        next
+          if $installable->type eq 'udeb';
+
+        my $breaks
+          = $self->processable->binary_relation($installable->name, 'Breaks');
+        my $strong
+          = $self->processable->binary_relation($installable->name, 'strong');
+
+        $self->pointed_hint('package-uses-dh-runit-but-lacks-breaks-substvar',
+            $drules->pointer,$installable->name)
+          if $seen{'runit'}
+          && $strong->satisfies('runit:any')
+          && (any { m{^ etc/sv/ }msx } @{$installable->installed->sorted_list})
+          && !$breaks->satisfies($DOLLAR . '{runit:Breaks}');
+    }
+
+    my $virtual_compat;
+
+    $build_prerequisites->visit(
+        sub {
+            return 0
+              unless
+              m{^ debhelper-compat (?: : \S+ )? \s+ [(]= \s+ (\d+) [)] $}x;
+
+            $virtual_compat = $1;
+
+            return 1;
+        },
+        Lintian::Relation::VISIT_PRED_FULL
+          | Lintian::Relation::VISIT_STOP_FIRST_MATCH
+    );
+
+    my $control_item=$self->processable->debian_control->item;
+
+    $self->pointed_hint('debhelper-compat-virtual-relation',
+        $control_item->pointer, $virtual_compat)
+      if length $virtual_compat;
+
+    # gives precedence to virtual compat
+    $debhelper_level = $virtual_compat
+      if length $virtual_compat;
+
+    my $compat_file = $droot->child('compat');
+
+    $self->hint('debhelper-compat-file-is-missing')
+      unless ($compat_file && $compat_file->is_open_ok)
+      || $virtual_compat;
+
+    my $from_compat_file = $self->check_compat_file;
+
+    if (length $debhelper_level && length $from_compat_file) {
+
+        $self->pointed_hint(
+            'declares-possibly-conflicting-debhelper-compat-versions',
+            $compat_file->pointer,$from_compat_file,'vs elsewhere',
+            $debhelper_level);
+    }
+
+    # this is not just to fill in the gap, but because debhelper
+    # prefers DH_COMPAT over debian/compat
+    $debhelper_level ||= $from_compat_file;
+
+    $self->hint('debhelper-compat-level', $debhelper_level)
+      if length $debhelper_level;
+
+    $debhelper_level ||= 1;
+
+    $self->hint('package-uses-deprecated-debhelper-compat-version',
+        $debhelper_level)
+      if $debhelper_level < $DEBHELPER_LEVELS->value('deprecated');
+
+    $self->hint('package-uses-old-debhelper-compat-version', $debhelper_level)
+      if $debhelper_level >= $DEBHELPER_LEVELS->value('deprecated')
+      && $debhelper_level < $DEBHELPER_LEVELS->value('recommended');
+
+    $self->hint('package-uses-experimental-debhelper-compat-version',
+        $debhelper_level)
+      if $debhelper_level >= $DEBHELPER_LEVELS->value('experimental');
+
+    $self->pointed_hint('dh-clean-k-is-deprecated', $drules->pointer)
+      if $seen_dh_clean_k;
+
+    for my $suffix (qw(enable start)) {
+
+        my ($stored_position, $focus)
+          = @{$overrides{"dh_systemd_$suffix"} // []};
+
+        $self->pointed_hint(
+            'debian-rules-uses-deprecated-systemd-override',
+            $drules->pointer($stored_position),
+            "override_dh_systemd_$suffix$focus"
+          )
+          if $stored_position
+          && $debhelper_level >= $BETTER_SYSTEMD_INTEGRATION;
+    }
+
+    my $num_overrides = scalar(keys %overrides);
+
+    $self->hint('excessive-debhelper-overrides', $num_overrides)
+      if $num_overrides >= $MANY_OVERRIDES;
+
+    $self->pointed_hint(
+        'debian-rules-uses-unnecessary-dh-argument',
+        $drules->pointer($seen_dh_parallel),
+        "$debhelper_level >= $DH_PARALLEL_NOT_NEEDED",
+        'dh ... --parallel'
+    )if $seen_dh_parallel && $debhelper_level >= $DH_PARALLEL_NOT_NEEDED;
+
+    $self->pointed_hint(
+        'debian-rules-uses-unnecessary-dh-argument',
+        $drules->pointer($seen_dh_systemd),
+        "$debhelper_level >= $INVOKES_SYSTEMD",
+        'dh ... --with=systemd'
+    )if $seen_dh_systemd && $debhelper_level >= $INVOKES_SYSTEMD;
+
+    for my $item ($droot->children) {
+
+        next
+          if !$item->is_symlink && !$item->is_file;
+
+        next
+          if $item->name eq $drules->name;
+
+        if ($item->basename =~ m/^(?:(.*)\.)?(?:post|pre)(?:inst|rm)$/) {
+
+            next
+              unless $modifies_scripts;
+
+            # They need to have #DEBHELPER# in their scripts.  Search
+            # for scripts that look like maintainer scripts and make
+            # sure the token is there.
+            my $installable_name = $1 || $EMPTY;
+            my $seentag = 0;
+
+            $seentag = 1
+              if $item->decoded_utf8 =~ /\#DEBHELPER\#/;
+
+            if (!$seentag) {
+
+                my $single_pkg = $EMPTY;
+                $single_pkg
+                  =  $self->processable->debian_control
+                  ->installable_package_type($installable_names[0])
+                  if scalar @installable_names == 1;
+
+                my $installable_type
+                  = $self->processable->debian_control
+                  ->installable_package_type($installable_name);
+
+                my $is_udeb = 0;
+
+                $is_udeb = 1
+                  if $installable_name && $installable_type eq 'udeb';
+
+                $is_udeb = 1
+                  if !$installable_name && $single_pkg eq 'udeb';
+
+                $self->pointed_hint('maintainer-script-lacks-debhelper-token',
+                    $item->pointer)
+                  unless $is_udeb;
+            }
+
+            next;
+        }
+
+        my $category = $item->basename;
+        $category =~ s/^.+\.//;
+
+        next
+          unless length $category;
+
+        # Check whether this is a debhelper config file that takes
+        # a list of filenames.
+        if ($FILENAME_CONFIGS->recognizes($category)) {
+
+            # The permissions of symlinks are not really defined, so resolve
+            # $item to ensure we are not dealing with a symlink.
+            my $actual = $item->resolve_path;
+            next
+              unless defined $actual;
+
+            $self->check_for_brace_expansion($item, $debhelper_level);
+
+            # debhelper only use executable files in compat 9
+            $self->pointed_hint('package-file-is-executable', $item->pointer)
+              if $actual->is_executable
+              && $debhelper_level < $USES_EXECUTABLE_FILES;
+
+            if ($debhelper_level >= $USES_EXECUTABLE_FILES) {
+
+                $self->pointed_hint(
+                    'executable-debhelper-file-without-being-executable',
+                    $item->pointer)
+                  if $actual->is_executable
+                  && !length $actual->hashbang;
+
+                # Only /usr/bin/dh-exec is allowed, even if
+                # /usr/lib/dh-exec/dh-exec-subst works too.
+                $self->pointed_hint('dh-exec-private-helper', $item->pointer)
+                  if $actual->is_executable
+                  && $actual->hashbang =~ m{^/usr/lib/dh-exec/};
+
+                # Do not make assumptions about the contents of an
+                # executable debhelper file, unless it's a dh-exec
+                # script.
+                if ($actual->hashbang =~ /dh-exec/) {
+
+                    $uses_dh_exec = 1;
+                    $self->check_dh_exec($item, $category);
+                }
+            }
+        }
+    }
+
+    $self->pointed_hint('package-uses-debhelper-but-lacks-build-depends',
+        $drules->pointer)
+      if $uses_debhelper
+      && !$build_prerequisites->satisfies('debhelper:any')
+      && !$build_prerequisites->satisfies('debhelper-compat:any');
+
+    $self->pointed_hint('package-uses-dh-exec-but-lacks-build-depends',
+        $drules->pointer)
+      if $uses_dh_exec
+      && !$build_prerequisites->satisfies('dh-exec:any');
+
+    for my $prerequisite (keys %command_by_prerequisite) {
+
+        my $command = $command_by_prerequisite{$prerequisite};
+
+        # handled above
+        next
+          if $prerequisite eq 'debhelper:any';
+
+        next
+          if $debhelper_level >= $REQUIRES_AUTOTOOLS
+          && (any { $_ eq $prerequisite }
+            qw(autotools-dev:any dh-strip-nondeterminism:any));
+
+        $self->pointed_hint('missing-build-dependency-for-dh_-command',
+            $drules->pointer,$command, "(does not satisfy $prerequisite)")
+          unless $build_prerequisites_norestriction->satisfies($prerequisite);
+    }
+
+    for my $prerequisite (keys %addon_by_prerequisite) {
+
+        my $addon = $addon_by_prerequisite{$prerequisite};
+
+        next
+          if $debhelper_level >= $REQUIRES_AUTOTOOLS
+          && $addon eq 'autoreconf';
+
+        $self->pointed_hint('missing-build-dependency-for-dh-addon',
+            $drules->pointer,$addon, "(does not satisfy $prerequisite)")
+          unless (
+            $build_prerequisites_norestriction->satisfies($prerequisite));
+
+        # As a special case, the python3 addon needs a dependency on
+        # dh-python unless the -dev packages are used.
+        my $python_source
+          = 'dh-python:any | dh-sequence-python3:any | pybuild-plugin-pyproject:any';
+
+        $self->pointed_hint('missing-build-dependency-for-dh-addon',
+            $drules->pointer,$addon, "(does not satisfy $python_source)")
+          if $addon eq 'python3'
+          && $build_prerequisites_norestriction->satisfies($prerequisite)
+          && !$build_prerequisites_norestriction->satisfies(
+            'python3-dev:any | python3-all-dev:any')
+          && !$build_prerequisites_norestriction->satisfies($python_source);
+    }
+
+    $self->hint('no-versioned-debhelper-prerequisite', $debhelper_level)
+      unless $build_prerequisites->satisfies(
+        "debhelper:any (>= $debhelper_level~)")
+      || $build_prerequisites->satisfies(
+        "debhelper-compat:any (= $debhelper_level)");
+
+    if ($debhelper_level >= $USES_AUTORECONF) {
+        for my $autotools_source (qw(dh-autoreconf:any autotools-dev:any)) {
+
+            next
+              if $autotools_source eq 'autotools-dev:any'
+              && $uses_autotools_dev_dh;
+
+            $self->hint('useless-autoreconf-build-depends',
+                "(does not need to satisfy $autotools_source)")
+              if $build_prerequisites->satisfies($autotools_source);
+        }
+    }
+
+    if ($seen_dh_sequencer && !$seen{'python2'}) {
+
+        my %python_depends;
+
+        for my $installable_name (@installable_names) {
+
+            $python_depends{$installable_name} = 1
+              if $self->processable->binary_relation($installable_name,'all')
+              ->satisfies($DOLLAR . '{python:Depends}');
+        }
+
+        $self->hint('python-depends-but-no-python-helper',
+            (sort keys %python_depends))
+          if %python_depends;
+    }
+
+    if ($seen_dh_sequencer && !$seen{'python3'}) {
+
+        my %python3_depends;
+
+        for my $installable_name (@installable_names) {
+
+            $python3_depends{$installable_name} = 1
+              if $self->processable->binary_relation($installable_name,'all')
+              ->satisfies($DOLLAR . '{python3:Depends}');
+        }
+
+        $self->hint('python3-depends-but-no-python3-helper',
+            (sort keys %python3_depends))
+          if %python3_depends;
+    }
+
+    if ($seen{'sphinxdoc'} && !$seen_dh_dynamic) {
+
+        my $seen_sphinxdoc = 0;
+
+        for my $installable_name (@installable_names) {
+            $seen_sphinxdoc = 1
+              if $self->processable->binary_relation($installable_name,'all')
+              ->satisfies($DOLLAR . '{sphinxdoc:Depends}');
+        }
+
+        $self->pointed_hint('sphinxdoc-but-no-sphinxdoc-depends',
+            $drules->pointer)
+          unless $seen_sphinxdoc;
+    }
+
+    return;
+}
+
+sub check_for_brace_expansion {
+    my ($self, $item, $debhelper_level) = @_;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        next
+          if $line =~ /^\s*$/;
+
+        next
+          if $line =~ /^\#/
+          && $debhelper_level >= $BRACE_EXPANSION;
+
+        if ($line =~ /((?<!\\)\{(?:[^\s\\\}]*?,)+[^\\\}\s,]*,*\})/){
+            my $expansion = $1;
+
+            my $pointer = $item->pointer($position);
+
+            $self->pointed_hint('brace-expansion-in-debhelper-config-file',
+                $pointer, $expansion);
+
+            last;
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+sub check_compat_file {
+    my ($self) = @_;
+
+    # Check the compat file.  Do this separately from looping over all
+    # of the other files since we use the compat value when checking
+    # for brace expansion.
+
+    my $compat_file
+      = $self->processable->patched->resolve_path('debian/compat');
+
+    # missing file is dealt with elsewhere
+    return $EMPTY
+      unless $compat_file && $compat_file->is_open_ok;
+
+    my $debhelper_level;
+
+    open(my $fd, '<', $compat_file->unpacked_path)
+      or die encode_utf8('Cannot open ' . $compat_file->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        if ($position == 1) {
+
+            $debhelper_level = $line;
+            next;
+        }
+
+        my $pointer = $compat_file->pointer($position);
+
+        $self->pointed_hint('debhelper-compat-file-contains-multiple-levels',
+            $pointer)
+          if $line =~ /^\d/;
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    # trim both ends
+    $debhelper_level =~ s/^\s+|\s+$//g;
+
+    if (!length $debhelper_level) {
+
+        $self->pointed_hint('debhelper-compat-file-is-empty',
+            $compat_file->pointer);
+        return $EMPTY;
+    }
+
+    my $DEBHELPER_LEVELS = $self->data->debhelper_levels;
+
+    # Recommend people use debhelper-compat (introduced in debhelper
+    # 11.1.5~alpha1) over debian/compat, except for experimental/beta
+    # versions.
+    $self->pointed_hint('uses-debhelper-compat-file', $compat_file->pointer)
+      if $debhelper_level >= $VERSIONED_PREREQUISITE_AVAILABLE
+      && $debhelper_level < $DEBHELPER_LEVELS->value('experimental');
+
+    return $debhelper_level;
+}
+
+sub check_dh_exec {
+    my ($self, $item, $category) = @_;
+
+    return
+      unless $item->is_open_ok;
+
+    my $dhe_subst = 0;
+    my $dhe_install = 0;
+    my $dhe_filter = 0;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        chomp $line;
+
+        my $pointer = $item->pointer($position);
+
+        if ($line =~ /\$\{([^\}]+)\}/) {
+
+            my $sv = $1;
+            $dhe_subst = 1;
+
+            if (
+                $sv !~ m{ \A
+                   DEB_(?:BUILD|HOST)_(?:
+                       ARCH (?: _OS|_CPU|_BITS|_ENDIAN )?
+                      |GNU_ (?:CPU|SYSTEM|TYPE)|MULTIARCH
+             ) \Z}xsm
+            ) {
+                $self->pointed_hint('dh-exec-subst-unknown-variable',
+                    $pointer, $sv);
+            }
+        }
+
+        $dhe_install = 1
+          if $line =~ /[ \t]=>[ \t]/;
+
+        $dhe_filter = 1
+          if $line =~ /\[[^\]]+\]/;
+
+        $dhe_filter = 1
+          if $line =~ /<[^>]+>/;
+
+        if (   $line =~ /^usr\/lib\/\$\{([^\}]+)\}\/?$/
+            || $line
+            =~ /^usr\/lib\/\$\{([^\}]+)\}\/?\s+\/usr\/lib\/\$\{([^\}]+)\}\/?$/
+            || $line =~ /^usr\/lib\/\$\{([^\}]+)\}[^\s]+$/) {
+
+            my $sv = $1;
+            my $dv = $2;
+            my $dhe_useless = 0;
+
+            if (
+                $sv =~ m{ \A
+                   DEB_(?:BUILD|HOST)_(?:
+                       ARCH (?: _OS|_CPU|_BITS|_ENDIAN )?
+                      |GNU_ (?:CPU|SYSTEM|TYPE)|MULTIARCH
+             ) \Z}xsm
+            ) {
+                if (defined($dv)) {
+                    $dhe_useless = ($sv eq $dv);
+                } else {
+                    $dhe_useless = 1;
+                }
+            }
+
+            $self->pointed_hint('dh-exec-useless-usage', $pointer, $line)
+              if $dhe_useless && $item =~ /debian\/.*(install|manpages)/;
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    $self->pointed_hint('dh-exec-script-without-dh-exec-features',
+        $item->pointer)
+      if !$dhe_subst
+      && !$dhe_install
+      && !$dhe_filter;
+
+    $self->pointed_hint('dh-exec-install-not-allowed-here', $item->pointer)
+      if $dhe_install
+      && $category ne 'install'
+      && $category ne 'manpages';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debhelper/Temporary.pm b/lib/Lintian/Check/Debhelper/Temporary.pm
new file mode 100644
index 0000000..452d76c
--- /dev/null
+++ b/lib/Lintian/Check/Debhelper/Temporary.pm
@@ -0,0 +1,55 @@
+# debhelper/temporary -- lintian check script -*- perl -*-
+
+# Copyright (C) 1999 by Joey Hess
+# Copyright (C) 2016-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debhelper::Temporary;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->dirname eq 'debian/';
+
+    # The regex matches "debhelper", but debhelper/Dh_Lib does not
+    # make those, so skip it.
+    $self->pointed_hint('temporary-debhelper-file', $item->pointer)
+      if $item->basename =~ m{ (?: ^ | [.] ) debhelper (?: [.]log )? $}x
+      && $item->basename ne 'debhelper';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Changelog.pm b/lib/Lintian/Check/Debian/Changelog.pm
new file mode 100644
index 0000000..faa7890
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Changelog.pm
@@ -0,0 +1,970 @@
+# debian/changelog -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2019-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Changelog;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Data::Validate::Domain;
+use Date::Format qw(time2str);
+use Email::Address::XS;
+use List::Util qw(first);
+use List::SomeUtils qw(any all uniq);
+use Path::Tiny;
+use Syntax::Keyword::Try;
+use Unicode::UTF8 qw(valid_utf8 decode_utf8 encode_utf8);
+
+use Lintian::Changelog;
+use Lintian::Changelog::Version;
+use Lintian::IPC::Run3 qw(safe_qx);
+use Lintian::Relation::Version qw(versions_gt);
+use Lintian::Spelling qw(check_spelling);
+
+const my $EMPTY => q{};
+const my $DOUBLE_QUOTE => q{"};
+const my $GREATER_THAN => q{>};
+const my $APPROXIMATELY_EQUAL => q{~};
+
+const my $NOT_EQUALS => q{!=};
+const my $ARROW => q{->};
+
+const my $MAXIMUM_WIDTH => 82;
+const my $FIRST_ARCHIVED_BUG_NUMBER => 50_004;
+const my $OUT_OF_REACH_BUG_NUMBER => 1_500_000;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub spelling_tag_emitter {
+    my ($self, $tag_name, $item, @orig_args) = @_;
+
+    my $pointer = $item->pointer($.);
+
+    return sub {
+        return $self->pointed_hint($tag_name, $pointer, @orig_args, @_);
+    };
+}
+
+sub source {
+    my ($self) = @_;
+
+    my $pkg = $self->processable->name;
+    my $processable = $self->processable;
+    my $group = $self->group;
+
+    my $changelog = $processable->changelog;
+    return
+      unless defined $changelog;
+
+    my @entries = @{$changelog->entries};
+    return
+      unless @entries;
+
+    my $latest_entry = $entries[0];
+
+    my $changelog_item = $self->processable->changelog_item;
+    my $latest_pointer = $changelog_item->pointer($latest_entry->position);
+
+    my $changes = $group->changes;
+    if ($changes) {
+        my $contents = path($changes->path)->slurp;
+        # make sure dot matches newlines, as well
+        if ($contents =~ qr/BEGIN PGP SIGNATURE.*END PGP SIGNATURE/ms) {
+
+            $self->pointed_hint('unreleased-changelog-distribution',
+                $latest_pointer)
+              if $latest_entry->Distribution eq 'UNRELEASED';
+        }
+    }
+
+    my $versionstring = $processable->fields->value('Version');
+    my $latest_version = Lintian::Changelog::Version->new;
+
+    try {
+        $latest_version->assign($versionstring, $processable->native);
+
+    } catch {
+        my $indicator= ($processable->native ? $EMPTY : 'non-') . 'native';
+        $self->pointed_hint('malformed-debian-changelog-version',
+            $latest_pointer,$versionstring, "(for $indicator)");
+        undef $latest_version;
+
+        # perlcritic 1.140-1 requires a semicolon on the next line
+    };
+
+    if (defined $latest_version) {
+
+        $self->pointed_hint(
+            'hyphen-in-upstream-part-of-debian-changelog-version',
+            $latest_pointer,$latest_version->upstream)
+          if !$processable->native && $latest_version->upstream =~ qr/-/;
+
+        # unstable, testing, and stable shouldn't be used in Debian
+        # version numbers.  unstable should get a normal version
+        # increment and testing and stable should get suite-specific
+        # versions.
+        #
+        # NMUs get a free pass because they need to work with the
+        # version number that was already there.
+        unless (length $latest_version->source_nmu) {
+            my $revision = $latest_version->maintainer_revision;
+            my $distribution = $latest_entry->Distribution;
+
+            $self->pointed_hint('version-refers-to-distribution',
+                $latest_pointer,$latest_version->literal)
+              if ($revision =~ /testing|(?:un)?stable/i)
+              || (
+                ($distribution eq 'unstable'|| $distribution eq 'experimental')
+                && $revision
+                =~ /woody|sarge|etch|lenny|squeeze|stretch|buster/);
+        }
+
+        my $examine = $latest_version->maintainer_revision;
+        $examine = $latest_version->upstream
+          unless $processable->native;
+
+        my $candidate_pattern = qr/rc|alpha|beta|pre(?:view|release)?/;
+        my $increment_pattern = qr/[^a-z].*|\Z/;
+
+        my ($candidate_string, $increment_string)
+          = ($examine =~ m/[^~a-z]($candidate_pattern)($increment_pattern)/sm);
+        if (length $candidate_string && !length $latest_version->source_nmu) {
+
+            $increment_string //= $EMPTY;
+
+            # remove rc-part and any preceding symbol
+            my $expected = $examine;
+            $expected =~ s/[\.\+\-\:]?\Q$candidate_string\E.*//;
+
+            my $suggestion = "$expected~$candidate_string$increment_string";
+
+            $self->pointed_hint(
+                'rc-version-greater-than-expected-version',
+                $latest_pointer,
+                $examine,
+                $GREATER_THAN,
+                $expected,
+                "(consider using $suggestion)",
+              )
+              if $latest_version->maintainer_revision eq '1'
+              || $latest_version->maintainer_revision=~ /^0(?:\.1|ubuntu1)?$/
+              || $processable->native;
+        }
+    }
+
+    if (@entries > 1) {
+
+        my $previous_entry = $entries[1];
+        my $latest_timestamp = $latest_entry->Timestamp;
+        my $previous_timestamp = $previous_entry->Timestamp;
+
+        my $previous_version = Lintian::Changelog::Version->new;
+        try {
+            $previous_version->assign($previous_entry->Version,
+                $processable->native);
+        } catch {
+            my $indicator= ($processable->native ? $EMPTY : 'non-') . 'native';
+            $self->pointed_hint(
+                'odd-historical-debian-changelog-version',
+                $changelog_item->pointer($previous_entry->position),
+                $previous_entry->Version,
+                "(for $indicator)"
+            );
+            undef $previous_version;
+        }
+
+        if ($latest_timestamp && $previous_timestamp) {
+
+            $self->pointed_hint(
+                'latest-debian-changelog-entry-without-new-date',
+                $latest_pointer)
+              if $latest_timestamp <= $previous_timestamp
+              && lc($latest_entry->Distribution) ne 'unreleased';
+        }
+
+        if (defined $latest_version) {
+
+            # skip first
+            for my $entry (@entries[1..$#entries]) {
+
+                # cannot use parser; nativeness may differ
+                my ($no_epoch) = ($entry->Version =~ qr/^(?:[^:]+:)?([^:]+)$/);
+
+                next
+                  unless defined $no_epoch;
+
+                # disallowed even if epochs differ; see tag description
+                if (   $latest_version->no_epoch eq $no_epoch
+                    && $latest_entry->Source eq $entry->Source) {
+
+                    $self->pointed_hint(
+'latest-debian-changelog-entry-reuses-existing-version',
+                        $latest_pointer,
+                        $latest_version->literal,
+                        $APPROXIMATELY_EQUAL,
+                        $entry->Version,
+                        '(last used: '. $entry->Date . ')'
+                    );
+
+                    last;
+                }
+            }
+        }
+
+        if (defined $latest_version && defined $previous_version) {
+
+            # a reused version literal is caught by the broader previous check
+
+            # start with a reasonable default
+            my $expected_previous = $previous_version->literal;
+
+            $expected_previous = $latest_version->without_backport
+              if $latest_version->backport_release
+              && $latest_version->backport_revision
+              && $latest_version->debian_without_backport ne '0';
+
+            # find an appropriate prior version for a source NMU
+            if (length $latest_version->source_nmu) {
+
+                # can only do first nmu for now
+                $expected_previous = $latest_version->without_source_nmu
+                  if $latest_version->source_nmu eq '1'
+                  &&$latest_version->maintainer_revision =~ qr/\d+/
+                  && $latest_version->maintainer_revision ne '0';
+            }
+
+            $self->pointed_hint(
+                'changelog-file-missing-explicit-entry',$latest_pointer,
+                $previous_version->literal, $ARROW,
+                "$expected_previous (missing)", $ARROW,
+                $latest_version->literal
+              )
+              unless $previous_version->literal eq $expected_previous
+              || $latest_entry->Distribution eq 'bullseye'
+              || $previous_entry->Distribution eq 'bullseye'
+              || $latest_entry->Distribution =~ /-security$/i;
+
+            if (   $latest_version->epoch eq $previous_version->epoch
+                && $latest_version->upstream eq$previous_version->upstream
+                && $latest_entry->Source eq $previous_entry->Source
+                && !$processable->native) {
+
+                $self->pointed_hint(
+                    'possible-new-upstream-release-without-new-version',
+                    $latest_pointer)
+                  if $latest_entry->Changes
+                  =~ /^\s*\*\s+new\s+upstream\s+(?:\S+\s+)?release\b/im;
+
+                my $non_consecutive = 0;
+
+                $non_consecutive = 1
+                  if !length $latest_version->source_nmu
+                  && $latest_version->maintainer_revision =~ /^\d+$/
+                  && $previous_version->maintainer_revision =~ /^\d+$/
+                  && $latest_version->maintainer_revision
+                  != $previous_version->maintainer_revision + 1;
+
+                $non_consecutive = 1
+                  if $latest_version->maintainer_revision eq
+                  $previous_version->maintainer_revision
+                  && $latest_version->source_nmu =~ /^\d+$/
+                  && $previous_version->source_nmu =~ /^\d+$/
+                  && $latest_version->source_nmu
+                  != $previous_version->source_nmu + 1;
+
+                $non_consecutive = 1
+                  if $latest_version->source_nmu =~ /^\d+$/
+                  && !length $previous_version->source_nmu
+                  && $latest_version->source_nmu != 1;
+
+                $self->pointed_hint(
+                    'non-consecutive-debian-revision',
+                    $latest_pointer,$previous_version->literal,
+                    $ARROW,$latest_version->literal
+                )if $non_consecutive;
+            }
+
+            if ($latest_version->epoch ne $previous_version->epoch) {
+                $self->pointed_hint(
+                    'epoch-change-without-comment',$latest_pointer,
+                    $previous_version->literal, $ARROW,
+                    $latest_version->literal
+                )unless $latest_entry->Changes =~ /\bepoch\b/im;
+
+                $self->pointed_hint(
+                    'epoch-changed-but-upstream-version-did-not-go-backwards',
+                    $latest_pointer,$previous_version->literal,
+                    $ARROW,$latest_version->literal
+                  )
+                  unless $processable->native
+                  || versions_gt($previous_version->upstream,
+                    $latest_version->upstream);
+            }
+        }
+    }
+
+    return;
+}
+
+# no copyright in udebs
+sub binary {
+    my ($self) = @_;
+
+    my $pkg = $self->processable->name;
+    my $processable = $self->processable;
+    my $group = $self->group;
+
+    my $is_symlink = 0;
+    my $native_pkg;
+    my $foreign_pkg;
+    my @doc_files;
+
+    # skip packages which have a /usr/share/doc/$pkg -> foo symlink
+    my $docfile = $processable->installed->lookup("usr/share/doc/$pkg");
+    return
+      if defined $docfile && $docfile->is_symlink;
+
+    # trailing slash in indicates a directory
+    my $docdir = $processable->installed->lookup("usr/share/doc/$pkg/");
+    @doc_files = grep { $_->is_file || $_->is_symlink } $docdir->children
+      if defined $docdir;
+    my @news_files
+      = grep { $_->basename =~ m{\A NEWS\.Debian (?:\.gz)? \Z}ixsm }@doc_files;
+
+    $self->pointed_hint('debian-news-file-not-compressed', $_->pointer)
+      for grep { $_->basename !~ m{\.gz$} } @news_files;
+
+    $self->pointed_hint('wrong-name-for-debian-news-file', $_->pointer)
+      for grep { $_->basename =~ m{\.gz$} && $_->basename ne 'NEWS.Debian.gz' }
+      @news_files;
+
+    my @changelog_files = grep {
+        $_->basename =~ m{\A changelog (?:\.html|\.Debian)? (?:\.gz)? \Z}xsm
+    } @doc_files;
+
+    # ubuntu permits symlinks; their profile suppresses the tag
+    $self->pointed_hint('debian-changelog-file-is-a-symlink', $_->pointer)
+      for grep { $_->is_symlink } @changelog_files;
+
+    $self->pointed_hint('changelog-file-not-compressed', $_->pointer)
+      for grep { $_->basename !~ m{ \.gz \Z}xsm } @changelog_files;
+
+    # Check if changelog files are compressed with gzip -9.
+    # It's a bit of an open question here what we should do
+    # with a file named ChangeLog.  If there's also a
+    # changelog file, it might be a duplicate, or the packager
+    # may have installed NEWS as changelog intentionally.
+    for my $item (@changelog_files) {
+
+        next
+          unless $item->basename =~ m{ \.gz \Z}xsm;
+
+        my $resolved = $item->resolve_path;
+        next
+          unless defined $resolved;
+
+        $self->pointed_hint('changelog-not-compressed-with-max-compression',
+            $item->pointer)
+          unless $resolved->file_type =~ /max compression/;
+    }
+
+    my @html_changelogs
+      = grep { $_->basename =~ /^changelog\.html(?:\.gz)?$/ } @changelog_files;
+    my @text_changelogs
+      = grep { $_->basename =~ /^changelog(?:\.gz)?$/ } @changelog_files;
+
+    if (!@text_changelogs) {
+
+        $self->pointed_hint('html-changelog-without-text-version', $_->pointer)
+          for @html_changelogs;
+    }
+
+    my $packagepath = 'usr/share/doc/' . $self->processable->name;
+    my $news_item
+      = $self->processable->installed->resolve_path(
+        "$packagepath/NEWS.Debian.gz");
+
+    my $news;
+    if (defined $news_item && $news_item->is_file) {
+
+        my $bytes = safe_qx('gunzip', '-c', $news_item->unpacked_path);
+
+        # another check complains about invalid encoding
+        if (valid_utf8($bytes)) {
+
+            my $contents = decode_utf8($bytes);
+            my $newslog = Lintian::Changelog->new;
+            $newslog->parse($contents);
+
+            for my $error (@{$newslog->errors}) {
+
+                my $position = $error->[0];
+                my $condition = $error->[1];
+
+                my $pointer = $news_item->pointer($position);
+
+                $self->pointed_hint('syntax-error-in-debian-news-file',
+                    $pointer, $DOUBLE_QUOTE . $condition . $DOUBLE_QUOTE);
+            }
+
+            # Some checks on the most recent entry.
+            if ($newslog->entries && defined @{$newslog->entries}[0]) {
+
+                $news = @{$newslog->entries}[0];
+
+                my $pointer = $news_item->pointer($news->position);
+
+                $self->pointed_hint(
+                    'debian-news-entry-has-strange-distribution',
+                    $pointer,$news->Distribution)
+                  if length $news->Distribution
+                  && $news->Distribution eq 'UNRELEASED';
+
+                check_spelling(
+                    $self->data,
+                    $news->Changes,
+                    $group->spelling_exceptions,
+                    $self->spelling_tag_emitter(
+                        'spelling-error-in-news-debian', $news_item
+                    )
+                );
+
+                $self->pointed_hint('debian-news-entry-uses-asterisk',$pointer)
+                  if $news->Changes =~ /^ \s* [*] \s /x;
+            }
+        }
+    }
+
+    # is this a native Debian package?
+    # If the version is missing, we assume it to be non-native
+    # as it is the most likely case.
+    my $source = $processable->fields->value('Source');
+    my $source_version;
+    if ($processable->fields->declares('Source') && $source =~ m/\((.*)\)/) {
+        $source_version = $1;
+    } else {
+        $source_version = $processable->fields->value('Version');
+    }
+    if (defined $source_version) {
+        $native_pkg = ($source_version !~ m/-/);
+    } else {
+        # We do not know, but assume it to non-native as it is
+        # the most likely case.
+        $native_pkg = 0;
+    }
+    $source_version = $processable->fields->value('Version') || '0-1';
+    $foreign_pkg = (!$native_pkg && $source_version !~ m/-0\./);
+    # A version of 1.2.3-0.1 could be either, so in that
+    # case, both vars are false
+
+    if ($native_pkg) {
+        # native Debian package
+        if (any { m/^changelog(?:\.gz)?$/} map { $_->basename } @doc_files) {
+            # everything is fine
+        } elsif (my $chg
+            = first {$_->basename =~ m/^changelog[.]debian(?:\.gz)$/i;}
+            @doc_files) {
+            $self->pointed_hint('wrong-name-for-changelog-of-native-package',
+                $chg->pointer);
+
+        } else {
+            $self->hint(
+                'no-changelog',
+                "usr/share/doc/$pkg/changelog.gz",
+                '(native package)'
+            );
+        }
+    } else {
+        # non-native (foreign :) Debian package
+
+        # 1. check for upstream changelog
+        my $found_upstream_text_changelog = 0;
+        if (
+            any { m/^changelog(\.html)?(?:\.gz)?$/ }
+            map { $_->basename } @doc_files
+        ) {
+            $found_upstream_text_changelog = 1 unless $1;
+            # everything is fine
+        } else {
+            # search for changelogs with wrong file name
+            for my $item (@doc_files) {
+
+                if (   $item->basename =~ m/^change/i
+                    && $item->basename !~ m/debian/i) {
+
+                    $self->pointed_hint('wrong-name-for-upstream-changelog',
+                        $item->pointer);
+                    last;
+                }
+            }
+        }
+
+        # 2. check for Debian changelog
+        if (
+            any { m/^changelog\.Debian(?:\.gz)?$/ }
+            map { $_->basename } @doc_files
+        ) {
+            # everything is fine
+        } elsif (my $chg
+            = first {$_->basename =~ m/^changelog\.debian(?:\.gz)?$/i;}
+            @doc_files) {
+            $self->pointed_hint('wrong-name-for-debian-changelog-file',
+                $chg->pointer);
+
+        } else {
+            if ($foreign_pkg && $found_upstream_text_changelog) {
+                $self->hint('debian-changelog-file-missing-or-wrong-name');
+
+            } elsif ($foreign_pkg) {
+                $self->hint(
+                    'no-changelog',
+                    "usr/share/doc/$pkg/changelog.Debian.gz",
+                    '(non-native package)'
+                );
+            }
+            # TODO: if uncertain whether foreign or native, either
+            # changelog.gz or changelog.debian.gz should exists
+            # though... but no tests catches this (extremely rare)
+            # border case... Keep in mind this is only happening if we
+            # have a -0.x version number... So not my priority to fix
+            # --Jeroen
+        }
+    }
+
+    my $changelog_item = $self->processable->changelog_item;
+    return
+      unless defined $changelog_item;
+
+    # another check complains about invalid encoding
+    my $changelog = $processable->changelog;
+
+    for my $error (@{$changelog->errors}) {
+
+        my $position = $error->[0];
+        my $condition = $error->[1];
+
+        my $pointer = $changelog_item->pointer($position);
+
+        $self->pointed_hint('syntax-error-in-debian-changelog',
+            $pointer, $DOUBLE_QUOTE . $condition . $DOUBLE_QUOTE);
+    }
+
+    # Check for some things in the raw changelog file and compute the
+    # "offset" to the first line of the first entry.  We use this to
+    # report the line number of "too-long" lines.  (#657402)
+    my $real_start = $self->check_dch($changelog_item);
+
+    my @entries = @{$changelog->entries};
+
+    # all versions from the changelog
+    my %allversions
+      = map { $_ => 1 } grep { defined } map { $_->Version } @entries;
+
+    # checks applying to all entries
+    for my $entry (@entries) {
+
+        my $position = $entry->position;
+        my $version = $entry->Version;
+
+        my $pointer = $changelog_item->pointer($position);
+
+        if (length $entry->Maintainer) {
+            my ($parsed) = Email::Address::XS->parse($entry->Maintainer);
+
+            unless ($parsed->is_valid) {
+
+                $self->pointed_hint(
+                    'bogus-mail-host-in-debian-changelog',
+                    $pointer,$entry->Maintainer,"(for version $version)",
+                );
+                next;
+            }
+
+            unless (all { length }
+                ($parsed->address, $parsed->user, $parsed->host)) {
+                $self->pointed_hint(
+                    'bogus-mail-host-in-debian-changelog',
+                    $pointer,$parsed->format,"(for version $version)",
+                );
+                next;
+            }
+
+            $self->pointed_hint(
+                'bogus-mail-host-in-debian-changelog',
+                $pointer, $parsed->address,"(for version $version)",
+              )
+              unless is_domain($parsed->host,
+                {domain_disable_tld_validation => 1});
+        }
+    }
+
+    my $INVALID_DATES
+      = $self->data->load('changelog-file/invalid-dates',qr/\s*=\>\s*/);
+
+    if (@entries) {
+
+        # checks related to the latest entry
+        my $latest_entry = $entries[0];
+
+        my $latest_pointer = $changelog_item->pointer($latest_entry->position);
+
+        my $latest_timestamp = $latest_entry->Timestamp;
+
+        if ($latest_timestamp) {
+
+            my $warned = 0;
+            my $longdate = $latest_entry->Date;
+
+            for my $re ($INVALID_DATES->all()) {
+                if ($longdate =~ m/($re)/i) {
+
+                    my $match = $1;
+                    my $repl = $INVALID_DATES->value($re);
+
+                    $self->pointed_hint('invalid-date-in-debian-changelog',
+                        $latest_pointer,"($match", $ARROW, "$repl)");
+
+                    $warned = 1;
+                }
+            }
+
+            my ($weekday_declared, $numberportion)
+              = split(m/,\s*/, $longdate, 2);
+            $numberportion //= $EMPTY;
+            my ($tz, $weekday_actual);
+
+            if ($numberportion =~ m/[ ]+ ([^ ]+)\Z/xsm) {
+                $tz = $1;
+                $weekday_actual = time2str('%a', $latest_timestamp, $tz);
+            }
+
+            if (not $warned and $tz and $weekday_declared ne $weekday_actual) {
+                my $real_weekday = time2str('%A', $latest_timestamp, $tz);
+                my $short_date = time2str('%Y-%m-%d', $latest_timestamp, $tz);
+                $self->pointed_hint('debian-changelog-has-wrong-day-of-week',
+                    $latest_pointer,"$short_date was a $real_weekday");
+            }
+        }
+
+        # there is more than one changelog entry
+        if (@entries > 1) {
+
+            my $previous_entry = $entries[1];
+
+            my $previous_timestamp = $previous_entry->Timestamp;
+
+            $self->pointed_hint('latest-changelog-entry-without-new-date',
+                $latest_pointer)
+              if defined $latest_timestamp
+              && defined $previous_timestamp
+              && $latest_timestamp <= $previous_timestamp
+              && $latest_entry->Distribution ne 'UNRELEASED';
+
+            my $latest_dist = lc $latest_entry->Distribution;
+            my $previous_dist = lc $previous_entry->Distribution;
+
+            $self->pointed_hint('experimental-to-unstable-without-comment',
+                $latest_pointer)
+              if $latest_dist eq 'unstable'
+              && $previous_dist eq 'experimental'
+              && $latest_entry->Changes
+              !~ m{ \b to \s+ ['"\N{LEFT SINGLE QUOTATION MARK}\N{LEFT DOUBLE QUOTATION MARK}]? (?:unstable|sid) ['"\N{RIGHT SINGLE QUOTATION MARK}\N{RIGHT DOUBLE QUOTATION MARK}]? \b }imx;
+
+            my $changes = $group->changes;
+            if ($changes) {
+                my $changes_dist= lc $changes->fields->value('Distribution');
+
+                my %codename;
+                $codename{'unstable'} = 'sid';
+                my @normalized
+                  = uniq map { $codename{$_} // $_ }
+                  ($latest_dist, $changes_dist);
+
+                $self->pointed_hint(
+                    'changelog-distribution-does-not-match-changes-file',
+                    $latest_pointer,$latest_dist,
+                    $NOT_EQUALS, $changes_dist
+                )unless @normalized == 1;
+            }
+
+        }
+
+        # Some checks should only be done against the most recent
+        # changelog entry.
+        my $changes = $latest_entry->Changes || $EMPTY;
+
+        if (@entries == 1) {
+
+            if ($latest_entry->Version && $latest_entry->Version =~ /-1$/) {
+                $self->pointed_hint('initial-upload-closes-no-bugs',
+                    $latest_pointer)
+                  unless @{ $latest_entry->Closes };
+
+                $self->pointed_hint(
+                    'new-package-uses-date-based-version-number',
+                    $latest_pointer,
+                    $latest_entry->Version,
+                    '(better: 0~' . $latest_entry->Version .')'
+                )if $latest_entry->Version =~ m/^\d{8}/;
+            }
+
+            $self->pointed_hint('changelog-is-dh_make-template',
+                $latest_pointer)
+              if $changes
+              =~ /(?:#?\s*)(?:\d|n)+ is the bug number of your ITP/i;
+        }
+
+        while ($changes =~ /(closes[\s;]*(?:bug)?\#?\s?\d{6,})[^\w]/ig) {
+
+            my $closes = $1;
+
+            $self->pointed_hint('possible-missing-colon-in-closes',
+                $latest_pointer, $closes)
+              if length $closes;
+        }
+
+        if ($changes =~ m/(TEMP-\d{7}-[0-9a-fA-F]{6})/) {
+
+            my $temporary_cve = $1;
+
+            $self->pointed_hint(
+                'changelog-references-temp-security-identifier',
+                $latest_pointer, $temporary_cve);
+        }
+
+        # check for bad intended distribution
+        if (
+            $changes =~ m{uploads? \s+ to \s+
+                            (?'intended'testing|unstable|experimental|sid)}xi
+        ){
+            my $intended = lc($+{intended});
+
+            $intended = 'unstable'
+              if $intended eq 'sid';
+
+            my $uploaded = $latest_entry->Distribution;
+
+            $self->pointed_hint('bad-intended-distribution', $latest_pointer,
+                "intended for $intended but uploaded to $uploaded")
+              if $uploaded ne $intended
+              && $uploaded ne 'UNRELEASED';
+        }
+
+        if ($changes =~ m{ (Close: \s+ [#] \d+) }xi) {
+
+            my $statement = $1;
+
+            $self->pointed_hint('misspelled-closes-bug', $latest_pointer,
+                $statement);
+        }
+
+        my $changesempty = $changes;
+        $changesempty =~ s/\W//gms;
+
+        $self->pointed_hint('changelog-empty-entry', $latest_pointer)
+          if !length $changesempty
+          && $latest_entry->Distribution ne 'UNRELEASED';
+
+        # before bug 50004 bts removed bug instead of archiving
+        for my $bug (@{$latest_entry->Closes}) {
+
+            $self->pointed_hint('improbable-bug-number-in-closes',
+                $latest_pointer, $bug)
+              if $bug < $FIRST_ARCHIVED_BUG_NUMBER
+              || $bug >= $OUT_OF_REACH_BUG_NUMBER;
+        }
+
+        # Compare against NEWS.Debian if available.
+        for my $field (qw/Distribution Urgency/) {
+
+            $self->pointed_hint(
+                'changelog-news-debian-mismatch',
+                $news_item->pointer($news->position),
+                $field,
+                $latest_entry->$field,
+                $NOT_EQUALS,
+                $news->$field
+              )
+              if defined $news
+              && length $news->Version
+              && $news->Version eq $latest_entry->Version
+              && $news->$field ne $latest_entry->$field;
+        }
+
+        $self->pointed_hint(
+            'debian-news-entry-has-unknown-version',
+            $news_item->pointer($news->position),
+            $news->Version
+          )
+          if defined $news
+          && length $news->Version
+          && !exists $allversions{$news->Version};
+
+        # Parse::DebianChangelog adds an additional space to the
+        # beginning of each line, so we have to adjust for that in the
+        # length check.
+        my @lines = split(/\n/, $changes);
+
+        # real start
+        my $position = $real_start;
+        for my $line (@lines) {
+
+            my $pointer = $changelog_item->pointer($position);
+
+            if ($line =~ /^   [*]\s(.{1,5})$/) {
+
+                my $excerpt = $1;
+
+                $self->pointed_hint('debian-changelog-line-too-short',
+                    $pointer, $excerpt)
+                  unless $1 =~ /:$/;
+            }
+
+            $self->pointed_hint('debian-changelog-line-too-long', $pointer)
+              if length $line >= $MAXIMUM_WIDTH
+              && $line !~ /^ [\s.o*+-]* (?: [Ss]ee:?\s+ )? \S+ $/msx;
+
+        } continue {
+            ++$position;
+        }
+
+        # Strip out all lines that contain the word spelling to avoid false
+        # positives on changelog entries for spelling fixes.
+        $changes =~ s/^.*(?:spelling|typo).*\n//gm;
+
+        check_spelling(
+            $self->data,
+            $changes,
+            $group->spelling_exceptions,
+            $self->spelling_tag_emitter(
+                'spelling-error-in-changelog', $changelog_item
+            )
+        );
+    }
+
+    return;
+}
+
+# read the changelog itself and check for some issues we cannot find
+# with Parse::DebianChangelog.  Also return the "real" line number for
+# the first line of text in the first entry.
+#
+sub check_dch {
+    my ($self) = @_;
+
+    my $unresolved = $self->processable->changelog_item;
+
+    # stop for dangling symbolic link
+    my $item = $unresolved->resolve_path;
+    return 0
+      unless defined $item;
+
+    # return empty changelog
+    return 0
+      unless $item->is_file && $item->is_open_ok;
+
+    # emacs only looks at the last "local variables" in a file, and only at
+    # one within 3000 chars of EOF and on the last page (^L), but that's a bit
+    # pesky to replicate.  Demanding a match of $prefix and $suffix ought to
+    # be enough to avoid false positives.
+
+    my $contents;
+    if ($item->basename =~ m{ [.]gz $}x) {
+
+        my $bytes = safe_qx('gunzip', '-c', $item->unpacked_path);
+
+        return 0
+          unless valid_utf8($bytes);
+
+        $contents = decode_utf8($bytes);
+
+    } else {
+
+        # empty unless valis UTF-8
+        $contents = $item->decoded_utf8;
+    }
+
+    my @lines = split(m{\n}, $contents);
+
+    my $prefix;
+    my $suffix;
+    my $real_start = 0;
+
+    my $saw_tab_lead = 0;
+
+    my $position = 1;
+    for my $line (@lines) {
+
+        ++$real_start
+          unless $saw_tab_lead;
+
+        $saw_tab_lead = 1
+          if $line =~ /^\s+\S/;
+
+        my $pointer = $item->pointer($position);
+
+        if (
+            $line
+            =~ m{ closes: \s* (( (?:bug)? [#]? \s? \d*) [[:alpha:]] \w*) }ix
+            || $line =~ m{ closes: \s* (?:bug)? [#]? \s? \d+
+              (?: , \s* (?:bug)? [#]? \s? \d+ )*
+              (?: , \s* (( (?:bug)? [#]? \s? \d* ) [[:alpha:]] \w*)) }ix
+        ) {
+
+            my $bug = $1;
+
+            $self->pointed_hint('wrong-bug-number-in-closes', $pointer, $bug)
+              if length $2;
+        }
+
+        if ($line =~ /^(.*)Local\ variables:(.*)$/i) {
+            $prefix = $1;
+            $suffix = $2;
+        }
+
+        # emacs allows whitespace between prefix and variable, hence \s*
+        $self->pointed_hint(
+            'debian-changelog-file-contains-obsolete-user-emacs-settings',
+            $pointer)
+          if defined $prefix
+          && defined $suffix
+          && $line =~ /^\Q$prefix\E\s*add-log-mailing-address:.*\Q$suffix\E$/;
+
+    } continue {
+        ++$position;
+    }
+
+    return $real_start;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Field/Adopted.pm b/lib/Lintian/Check/Debian/Control/Field/Adopted.pm
new file mode 100644
index 0000000..d9d9379
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Field/Adopted.pm
@@ -0,0 +1,98 @@
+# debian/control/field/adopted -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Field::Adopted;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+    my $source_fields = $control->source_fields;
+
+    my $KNOWN_SOURCE_FIELDS= $self->data->load('common/source-fields');
+    my $KNOWN_BINARY_FIELDS= $self->data->load('fields/binary-fields');
+
+    for my $field ($source_fields->names) {
+
+        my ($marker, $bare) = split(qr{-}, $field, 2);
+
+        next
+          unless length $marker
+          && length $bare;
+
+        my $control_item= $self->processable->debian_control->item;
+        my $position = $source_fields->position($field);
+        my $pointer = $control_item->pointer($position);
+
+        # case-insensitive match
+        $self->pointed_hint(
+            'adopted-extended-field',$pointer,
+            '(in section for source)', $field
+          )
+          if $marker =~ m{^ X }ix
+          && $KNOWN_SOURCE_FIELDS->resembles($bare);
+    }
+
+    for my $installable ($control->installables) {
+        my $installable_fields = $control->installable_fields($installable);
+
+        for my $field ($installable_fields->names) {
+
+            my ($marker, $bare) = split(qr{-}, $field, 2);
+
+            next
+              unless length $marker
+              && length $bare;
+
+            my $control_item= $self->processable->debian_control->item;
+            my $position = $installable_fields->position($field);
+            my $pointer = $control_item->pointer($position);
+
+            # case-insensitive match
+            $self->pointed_hint(
+                'adopted-extended-field', $pointer,
+                "(in section for $installable)", $field
+              )
+              if $marker =~ m{^ X }ix
+              && $KNOWN_BINARY_FIELDS->resembles($bare);
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Field/Architecture/Multiline.pm b/lib/Lintian/Check/Debian/Control/Field/Architecture/Multiline.pm
new file mode 100644
index 0000000..dbb5dc2
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Field/Architecture/Multiline.pm
@@ -0,0 +1,63 @@
+# debian/control/field/architecture/multiline -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Field::Architecture::Multiline;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+
+    for my $installable ($control->installables) {
+
+        my $installable_fields = $control->installable_fields($installable);
+
+        my $field = 'Architecture';
+
+        my $control_item= $self->processable->debian_control->item;
+        my $position = $installable_fields->position($field);
+        my $pointer = $control_item->pointer($position);
+
+        $self->pointed_hint('multiline-architecture-field',
+            $pointer, $field,"(in section for $installable)")
+          if $installable_fields->value($field)=~ /\n./;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Field/BuildProfiles.pm b/lib/Lintian/Check/Debian/Control/Field/BuildProfiles.pm
new file mode 100644
index 0000000..50e9663
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Field/BuildProfiles.pm
@@ -0,0 +1,110 @@
+# debian/control/field/build-profiles -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Field::BuildProfiles;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::Relation;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+
+    my $KNOWN_BUILD_PROFILES= $self->data->load('fields/build-profiles');
+
+    for my $installable ($control->installables) {
+        my $installable_fields = $control->installable_fields($installable);
+
+        my $field = 'Build-Profiles';
+
+        my $raw = $installable_fields->value($field);
+        next
+          unless $raw;
+
+        my $control_item= $self->processable->debian_control->item;
+        my $position = $installable_fields->position($field);
+        my $pointer = $control_item->pointer($position);
+
+        if (
+            $raw!~ m{^\s*              # skip leading whitespace
+                     <                 # first list start
+                       !?[^\s<>]+      # (possibly negated) term
+                       (?:             # any additional terms
+                         \s+           # start with a space
+                         !?[^\s<>]+    # (possibly negated) term
+                       )*              # zero or more additional terms
+                     >                 # first list end
+                     (?:               # any additional restriction lists
+                       \s+             # start with a space
+                       <               # additional list start
+                         !?[^\s<>]+    # (possibly negated) term
+                         (?:           # any additional terms
+                           \s+         # start with a space
+                           !?[^\s<>]+  # (possibly negated) term
+                         )*            # zero or more additional terms
+                       >               # additional list end
+                     )*                # zero or more additional lists
+                     \s*$              # trailing spaces at the end
+              }x
+        ) {
+            $self->pointed_hint(
+                'invalid-restriction-formula-in-build-profiles-field',
+                $pointer, $raw,"(in section for $installable)");
+
+        } else {
+            # parse the field and check the profile names
+            $raw =~ s/^\s*<(.*)>\s*$/$1/;
+
+            for my $restrlist (split />\s+</, $raw) {
+                for my $profile (split /\s+/, $restrlist) {
+
+                    $profile =~ s/^!//;
+
+                    $self->pointed_hint(
+                        'invalid-profile-name-in-build-profiles-field',
+                        $pointer, $profile,"(in section for $installable)")
+                      unless $KNOWN_BUILD_PROFILES->recognizes($profile)
+                      || $profile =~ /^pkg\.[a-z0-9][a-z0-9+.-]+\../;
+                }
+            }
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Field/BuiltUsing.pm b/lib/Lintian/Check/Debian/Control/Field/BuiltUsing.pm
new file mode 100644
index 0000000..560f89b
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Field/BuiltUsing.pm
@@ -0,0 +1,66 @@
+# debian/control/field/built-using -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Field::BuiltUsing;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+
+    for my $installable ($control->installables) {
+        my $installable_fields= $control->installable_fields($installable);
+
+        my $field = 'Built-Using';
+
+        my $control_item= $self->processable->debian_control->item;
+        my $position = $installable_fields->position($field);
+        my $pointer = $control_item->pointer($position);
+
+        $self->pointed_hint(
+            'built-using-field-on-arch-all-package',$pointer,
+            "(in section for $installable)", $field,
+            $installable_fields->value($field)
+          )
+          if $installable_fields->declares($field)
+          && $installable_fields->value('Architecture') eq 'all';
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Field/Description/Duplicate.pm b/lib/Lintian/Check/Debian/Control/Field/Description/Duplicate.pm
new file mode 100644
index 0000000..294893b
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Field/Description/Duplicate.pm
@@ -0,0 +1,114 @@
+# debian/control/field/description/duplicate -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Field::Description::Duplicate;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+
+    my %installables_by_synopsis;
+    my %installables_by_exended;
+
+    for my $installable ($control->installables) {
+
+        next
+          if $control->installable_package_type($installable) eq 'udeb';
+
+        my $installable_fields = $control->installable_fields($installable);
+
+        my $description = $installable_fields->untrimmed_value('Description');
+        next
+          unless length $description;
+
+        my ($synopsis, $extended) = split(/\n/, $description, 2);
+
+        $synopsis //= $EMPTY;
+        $extended //= $EMPTY;
+
+        # trim both ends
+        $synopsis =~ s/^\s+|\s+$//g;
+        $extended =~ s/^\s+|\s+$//g;
+
+        if (length $synopsis) {
+            $installables_by_synopsis{$synopsis} //= [];
+            push(@{$installables_by_synopsis{$synopsis}}, $installable);
+        }
+
+        if (length $extended) {
+            $installables_by_exended{$extended} //= [];
+            push(@{$installables_by_exended{$extended}}, $installable);
+        }
+    }
+
+    # check for duplicate short description
+    for my $synopsis (keys %installables_by_synopsis) {
+
+        # Assume that substvars are correctly handled
+        next
+          if $synopsis =~ m/\$\{.+\}/;
+
+        $self->pointed_hint(
+            'duplicate-short-description',
+            $control->item->pointer,
+            (sort @{$installables_by_synopsis{$synopsis}})
+        )if scalar @{$installables_by_synopsis{$synopsis}} > 1;
+    }
+
+    # check for duplicate long description
+    for my $extended (keys %installables_by_exended) {
+
+        # Assume that substvars are correctly handled
+        next
+          if $extended =~ m/\$\{.+\}/;
+
+        $self->pointed_hint(
+            'duplicate-long-description',
+            $control->item->pointer,
+            (sort @{$installables_by_exended{$extended}})
+        )if scalar @{$installables_by_exended{$extended}} > 1;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Field/DoubledUp.pm b/lib/Lintian/Check/Debian/Control/Field/DoubledUp.pm
new file mode 100644
index 0000000..1e1e69a
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Field/DoubledUp.pm
@@ -0,0 +1,83 @@
+# debian/control/field/doubled-up -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Field::DoubledUp;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+    my $source_fields = $control->source_fields;
+
+    # something like "Maintainer: Maintainer: bad field"
+    my @doubled_up_source_fields
+      = grep { $source_fields->value($_) =~ m{^ \Q$_\E \s* : }ix }
+      $source_fields->names;
+
+    for my $field (@doubled_up_source_fields) {
+
+        my $control_item= $self->processable->debian_control->item;
+        my $position = $source_fields->position($field);
+        my $pointer = $control_item->pointer($position);
+
+        $self->pointed_hint('debian-control-repeats-field-name-in-value',
+            $pointer, '(in section for source)', $field);
+    }
+
+    for my $installable ($control->installables) {
+        my $installable_fields = $control->installable_fields($installable);
+
+        # something like "Maintainer: Maintainer: bad field"
+        my @doubled_up_installable_fields
+          = grep { $installable_fields->value($_) =~ m{^ \Q$_\E \s* : }ix }
+          $installable_fields->names;
+
+        for my $field (@doubled_up_installable_fields) {
+
+            my $control_item= $self->processable->debian_control->item;
+            my $position = $installable_fields->position($field);
+            my $pointer = $control_item->pointer($position);
+
+            $self->pointed_hint('debian-control-repeats-field-name-in-value',
+                $pointer,"(in section for $installable)", $field);
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Field/Empty.pm b/lib/Lintian/Check/Debian/Control/Field/Empty.pm
new file mode 100644
index 0000000..15b48ca
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Field/Empty.pm
@@ -0,0 +1,84 @@
+# debian/control/field/empty -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Field::Empty;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+    my $source_fields = $control->source_fields;
+
+    my @empty_source_fields
+      = grep { !length $source_fields->value($_) } $source_fields->names;
+
+    for my $field (@empty_source_fields) {
+
+        my $control_item= $self->processable->debian_control->item;
+        my $position = $source_fields->position($field);
+        my $pointer = $control_item->pointer($position);
+
+        $self->pointed_hint(
+            'debian-control-has-empty-field', $pointer,
+            '(in source paragraph)', $field
+        );
+    }
+
+    for my $installable ($control->installables) {
+        my $installable_fields = $control->installable_fields($installable);
+
+        my @empty_installable_fields
+          = grep { !length $installable_fields->value($_) }
+          $installable_fields->names;
+
+        for my $field (@empty_installable_fields) {
+
+            my $control_item= $self->processable->debian_control->item;
+            my $position = $installable_fields->position($field);
+            my $pointer = $control_item->pointer($position);
+
+            $self->pointed_hint(
+                'debian-control-has-empty-field',$pointer,
+                "(in section for $installable)", $field
+            );
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Field/Misplaced.pm b/lib/Lintian/Check/Debian/Control/Field/Misplaced.pm
new file mode 100644
index 0000000..743be38
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Field/Misplaced.pm
@@ -0,0 +1,67 @@
+# debian/control/field/misplaced -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Field::Misplaced;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+    my $source_fields = $control->source_fields;
+
+    my @build_fields
+      =qw{Build-Depends Build-Depends-Indep Build-Conflicts Build-Conflicts-Indep};
+
+    for my $installable ($control->installables) {
+        my $installable_fields = $control->installable_fields($installable);
+
+        for my $field (@build_fields) {
+
+            my $control_item= $self->processable->debian_control->item;
+            my $position = $installable_fields->position($field);
+            my $pointer = $control_item->pointer($position);
+
+            $self->pointed_hint('build-prerequisite-in-installable-section',
+                $pointer, $field,"(in section for $installable)")
+              if $installable_fields->declares($field);
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Field/Redundant.pm b/lib/Lintian/Check/Debian/Control/Field/Redundant.pm
new file mode 100644
index 0000000..9f78dd4
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Field/Redundant.pm
@@ -0,0 +1,68 @@
+# debian/control/field/redundant -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Field::Redundant;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+    my $source_fields = $control->source_fields;
+
+    for my $installable ($control->installables) {
+        my $installable_fields = $control->installable_fields($installable);
+
+        for my $field ($installable_fields->names) {
+
+            my $control_item= $self->processable->debian_control->item;
+            my $position = $installable_fields->position($field);
+            my $pointer = $control_item->pointer($position);
+
+            $self->pointed_hint(
+                'installable-field-mirrors-source',$pointer,
+                "(in section for $installable)", $field
+              )
+              if $source_fields->declares($field)
+              && $installable_fields->value($field) eq
+              $source_fields->value($field);
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Field/Relation.pm b/lib/Lintian/Check/Debian/Control/Field/Relation.pm
new file mode 100644
index 0000000..3047971
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Field/Relation.pm
@@ -0,0 +1,180 @@
+# debian/control/field/relation -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Field::Relation;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::Relation;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+    my $source_fields = $control->source_fields;
+
+    # Check that fields which should be comma-separated or
+    # pipe-separated have separators.  Places where this tends to
+    # cause problems are with wrapped lines such as:
+    #
+    #     Depends: foo, bar
+    #      baz
+    #
+    # or with substvars.  If two substvars aren't separated by a
+    # comma, but at least one of them expands to an empty string,
+    # there will be a lurking bug.  The result will be syntactically
+    # correct, but as soon as both expand into something non-empty,
+    # there will be a syntax error.
+    #
+    # The architecture list can contain things that look like packages
+    # separated by spaces, so we have to remove any architecture
+    # restrictions first.  This unfortunately distorts our report a
+    # little, but hopefully not too much.
+    #
+    # Also check for < and > relations.  dpkg-gencontrol warns about
+    # them and then transforms them in the output to <= and >=, but
+    # it's easy to miss the error message.  Similarly, check for
+    # duplicates, which dpkg-source eliminates.
+
+    for my $field (
+        qw(Build-Depends Build-Depends-Indep
+        Build-Conflicts Build-Conflicts-Indep)
+    ) {
+        next
+          unless $source_fields->declares($field);
+
+        my $control_item= $self->processable->debian_control->item;
+        my $position = $source_fields->position($field);
+        my $pointer = $control_item->pointer($position);
+
+        my @values = $source_fields->trimmed_list($field, qr{ \s* , \s* }x);
+        my @obsolete = grep { m{ [(] [<>] \s* [^<>=]+ [)] }x } @values;
+
+        $self->pointed_hint(
+            'obsolete-relation-form-in-source',
+            $pointer, '(in source paragraph)',
+            $field, $_
+        )for @obsolete;
+
+        my $raw = $source_fields->value($field);
+        my $relation = Lintian::Relation->new->load($raw);
+
+        for my $redundant_set ($relation->redundancies) {
+
+            $self->pointed_hint('redundant-control-relation', $pointer,
+                '(in source paragraph)',
+                $field,join(', ', sort @{$redundant_set}));
+        }
+
+        $self->check_separators($raw, $pointer, '(in source paragraph)');
+    }
+
+    for my $installable ($control->installables) {
+        my $installable_fields = $control->installable_fields($installable);
+
+        for my $field (
+            qw(Pre-Depends Depends Recommends Suggests Breaks
+            Conflicts Provides Replaces Enhances)
+        ) {
+            next
+              unless $installable_fields->declares($field);
+
+            my $control_item= $self->processable->debian_control->item;
+            my $position = $installable_fields->position($field);
+            my $pointer = $control_item->pointer($position);
+
+            my @values
+              = $installable_fields->trimmed_list($field, qr{ \s* , \s* }x);
+            my @obsolete = grep { m{ [(] [<>] \s* [^<>=]+ [)] }x } @values;
+
+            $self->pointed_hint(
+                'obsolete-relation-form-in-source',
+                $pointer, "(in section for $installable)",
+                $field, $_
+            )for @obsolete;
+
+            my $relation
+              = $self->processable->binary_relation($installable, $field);
+
+            for my $redundant_set ($relation->redundancies) {
+
+                $self->pointed_hint(
+                    'redundant-control-relation', $pointer,
+                    "(in section for $installable)", $field,
+                    join(', ', sort @{$redundant_set})
+                );
+            }
+
+            my $raw = $installable_fields->value($field);
+            $self->check_separators($raw, $pointer,
+                "(in section for $installable)");
+        }
+    }
+
+    return;
+}
+
+sub check_separators {
+    my ($self, $string, $pointer, $explainer) = @_;
+
+    $string =~ s/\n(\s)/$1/g;
+    $string =~ s/\[[^\]]*\]//g;
+
+    if (
+        $string =~ m{(?:^|\s)
+                   (
+                (?:\w[^\s,|\$\(]+|\$\{\S+:Depends\})\s*
+                (?:\([^\)]*\)\s*)?
+                   )
+                   \s+
+                   (
+                (?:\w[^\s,|\$\(]+|\$\{\S+:Depends\})\s*
+                (?:\([^\)]*\)\s*)?
+                   )}x
+    ) {
+        my ($prev, $next) = ($1, $2);
+
+        # trim right
+        $prev =~ s/\s+$//;
+        $next =~ s/\s+$//;
+
+        $self->pointed_hint('missing-separator-between-items',
+            $pointer,$explainer, "'$prev' and '$next'");
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Field/RulesRequiresRoot.pm b/lib/Lintian/Check/Debian/Control/Field/RulesRequiresRoot.pm
new file mode 100644
index 0000000..b97a673
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Field/RulesRequiresRoot.pm
@@ -0,0 +1,99 @@
+# debian/control/field/rules-requires-root -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Field::RulesRequiresRoot;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(first_value);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+    my $source_fields = $control->source_fields;
+
+    my @r3_misspelled = grep { $_ ne 'Rules-Requires-Root' }
+      grep { m{^ Rules? - Requires? - Roots? $}xi } $source_fields->names;
+
+    for my $field (@r3_misspelled) {
+
+        my $control_item= $self->processable->debian_control->item;
+        my $position = $source_fields->position($field);
+        my $pointer = $control_item->pointer($position);
+
+        $self->pointed_hint('spelling-error-in-rules-requires-root',
+            $pointer, $field);
+    }
+
+    my $control_item= $self->processable->debian_control->item;
+    my $position = $source_fields->position('Rules-Requires-Root');
+    my $pointer = $control_item->pointer($position);
+
+    $self->pointed_hint('rules-do-not-require-root', $pointer)
+      if $source_fields->value('Rules-Requires-Root') eq 'no';
+
+    $self->pointed_hint('rules-require-root-explicitly', $pointer)
+      if $source_fields->declares('Rules-Requires-Root')
+      && $source_fields->value('Rules-Requires-Root') ne 'no';
+
+    $self->pointed_hint('silent-on-rules-requiring-root', $pointer)
+      unless $source_fields->declares('Rules-Requires-Root');
+
+    if (  !$source_fields->declares('Rules-Requires-Root')
+        || $source_fields->value('Rules-Requires-Root') eq 'no') {
+
+        for my $installable ($self->group->get_installables) {
+
+            my $user_owned_item
+              = first_value { $_->owner ne 'root' || $_->group ne 'root' }
+            @{$installable->installed->sorted_list};
+
+            next
+              unless defined $user_owned_item;
+
+            my $owner = $user_owned_item->owner;
+            my $group = $user_owned_item->group;
+
+            $self->pointed_hint('rules-silently-require-root',
+                $pointer, $installable->name,
+                "($owner:$group)", $user_owned_item->name);
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Field/Section.pm b/lib/Lintian/Check/Debian/Control/Field/Section.pm
new file mode 100644
index 0000000..dd0ba52
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Field/Section.pm
@@ -0,0 +1,52 @@
+# debian/control/field/section -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Field::Section;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+    my $source_fields = $control->source_fields;
+
+    $self->pointed_hint('no-source-section', $control->item->pointer)
+      unless $source_fields->declares('Section');
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Field/Spacing.pm b/lib/Lintian/Check/Debian/Control/Field/Spacing.pm
new file mode 100644
index 0000000..070ebdf
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Field/Spacing.pm
@@ -0,0 +1,78 @@
+# debian/control/field/spacing -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Field::Spacing;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $item = $self->processable->debian_control->item;
+    return
+      unless defined $item;
+
+    my @lines = split(/\n/, $item->decoded_utf8);
+
+    my $position = 1;
+    while (defined(my $line = shift @lines)) {
+
+        # strip leading spaces
+        $line =~ s{\s*$}{};
+
+        next
+          if $line =~ m{^ [#]}x;
+
+        # line with field:
+        if ($line =~ m{^ (\S+) : }x) {
+
+            my $field = $1;
+
+            my $pointer = $item->pointer($position);
+
+            $self->pointed_hint('debian-control-has-unusual-field-spacing',
+                $pointer, $field)
+              unless $line =~ m{^ \S+ : [ ] \S }x
+              || $line =~ m{^ \S+ : $}x;
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Link.pm b/lib/Lintian/Check/Debian/Control/Link.pm
new file mode 100644
index 0000000..5f3f751
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Link.pm
@@ -0,0 +1,57 @@
+# debian/control/link -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Link;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $debian_dir = $self->processable->patched->resolve_path('debian/');
+    return
+      unless $debian_dir;
+
+    my $item = $debian_dir->child('control');
+    return
+      unless $item;
+
+    $self->pointed_hint('debian-control-file-is-a-symlink', $item->pointer)
+      if $item->is_symlink;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Prerequisite/Circular.pm b/lib/Lintian/Check/Debian/Control/Prerequisite/Circular.pm
new file mode 100644
index 0000000..7cd78e5
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Prerequisite/Circular.pm
@@ -0,0 +1,74 @@
+# debian/control/prerequisite/circular -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Prerequisite::Circular;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+
+    my @prerequisite_fields = qw(Pre-Depends Depends Recommends Suggests);
+
+    for my $installable ($control->installables) {
+        my $installable_fields = $control->installable_fields($installable);
+
+        for my $field (@prerequisite_fields) {
+
+            next
+              unless $control->installable_fields($installable)
+              ->declares($field);
+
+            my $relation
+              = $self->processable->binary_relation($installable, $field);
+
+            my $control_item= $self->processable->debian_control->item;
+            my $position = $installable_fields->position($field);
+            my $pointer = $control_item->pointer($position);
+
+            $self->pointed_hint(
+                'circular-installation-prerequisite',
+                $pointer, "(in section for $installable)",
+                $field,$relation->to_string
+            )if $relation->satisfies($installable);
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Prerequisite/Development.pm b/lib/Lintian/Check/Debian/Control/Prerequisite/Development.pm
new file mode 100644
index 0000000..948076f
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Prerequisite/Development.pm
@@ -0,0 +1,145 @@
+# debian/control/prerequisite/development -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Prerequisite::Development;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+
+    for my $installable ($control->installables) {
+        my $installable_fields = $control->installable_fields($installable);
+
+        next
+          unless $installable =~ /-dev$/;
+
+        my $field = 'Depends';
+
+        next
+          unless $installable_fields->declares($field);
+
+        my $control_item= $self->processable->debian_control->item;
+        my $position = $installable_fields->position($field);
+        my $pointer = $control_item->pointer($position);
+
+        my @depends
+          = $installable_fields->trimmed_list($field, qr{ \s* , \s* }x);
+
+        for my $other_name ($control->installables) {
+
+            next
+              if $other_name =~ /-(?:dev|docs?|common)$/;
+
+            next
+              unless $other_name =~ /^lib[\w.+-]+\d/;
+
+            my @relevant
+              = grep { m{ (?: ^ | [\s|] ) \Q$other_name\E (?: [\s|(] | \z ) }x }
+              @depends;
+
+            # If there are any alternatives here, something special is
+            # going on.  Assume that the maintainer knows what they're
+            # doing.  Otherwise, separate out just the versions.
+            next
+              if any { m{ [|] }x } @relevant;
+
+            my @unsorted;
+            for my $package (@relevant) {
+
+                $package =~ m{^ [\w.+-]+ \s* [(] ([^)]+) [)] }x;
+                push(@unsorted, ($1 // $EMPTY));
+            }
+
+            my @versions = sort @unsorted;
+
+            my $context;
+
+            # If there's only one mention of this package, the dependency
+            # should be tight.  Otherwise, there should be both >>/>= and
+            # <</<= dependencies that mention the source, binary, or
+            # upstream version.  If there are more than three mentions of
+            # the package, again something is weird going on, so we assume
+            # they know what they're doing.
+            if (@relevant == 1) {
+                unless ($versions[0]
+                    =~ /^\s*=\s*\$\{(?:binary:Version|Source-Version)\}/) {
+                    # Allow "pkg (= ${source:Version})" if (but only if)
+                    # the target is an arch:all package.  This happens
+                    # with a lot of mono-packages.
+                    #
+                    # Note, we do not check if the -dev package is
+                    # arch:all as well.  The version-substvars check
+                    # handles that for us.
+                    next
+                      if $control->installable_fields($other_name)
+                      ->value('Architecture') eq 'all'
+                      && $versions[0]
+                      =~ m{^ \s* = \s* \$[{]source:Version[}] }x;
+
+                    $context = $relevant[0];
+                }
+
+            } elsif (@relevant == 2) {
+                unless (
+                    $versions[0] =~ m{^ \s* <[=<] \s* \$[{]
+                        (?: (?:binary|source):(?:Upstream-)?Version
+                            | Source-Version) [}] }xsm
+                    && $versions[1] =~ m{^ \s* >[=>] \s* \$[{]
+                        (?: (?:binary|source):(?:Upstream-)?Version
+                        | Source-Version) [}] }xsm
+                ) {
+                    $context = "$relevant[0], $relevant[1]";
+                }
+            }
+
+            $self->pointed_hint('weak-library-dev-dependency',
+                $pointer, "(in section for $installable)",
+                $field, $context)
+              if length $context;
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Control/Prerequisite/Redundant.pm b/lib/Lintian/Check/Debian/Control/Prerequisite/Redundant.pm
new file mode 100644
index 0000000..08ea510
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Control/Prerequisite/Redundant.pm
@@ -0,0 +1,99 @@
+# debian/control/prerequisitie/redundant -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Control::Prerequisite::Redundant;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $ARROW => q{->};
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+
+    # Make sure that a stronger dependency field doesn't satisfy any of
+    # the elements of a weaker dependency field.  dpkg-gencontrol will
+    # fix this up for us, but we want to check the source package
+    # since dpkg-gencontrol may silently "fix" something that's a more
+    # subtle bug.
+
+    # ordered from stronger to weaker
+    my @ordered_fields = qw(Pre-Depends Depends Recommends Suggests);
+
+    for my $installable ($control->installables) {
+        my $installable_fields = $control->installable_fields($installable);
+
+        my @remaining_fields = @ordered_fields;
+
+        for my $stronger (@ordered_fields) {
+
+            shift @remaining_fields;
+
+            next
+              unless $control->installable_fields($installable)
+              ->declares($stronger);
+
+            my $control_item= $self->processable->debian_control->item;
+            my $position = $installable_fields->position($stronger);
+            my $pointer = $control_item->pointer($position);
+
+            my $relation
+              = $self->processable->binary_relation($installable,$stronger);
+
+            for my $weaker (@remaining_fields) {
+
+                my @prerequisites = $control->installable_fields($installable)
+                  ->trimmed_list($weaker, qr{\s*,\s*});
+
+                for my $prerequisite (@prerequisites) {
+
+                    $self->pointed_hint(
+                        'redundant-installation-prerequisite',$pointer,
+                        "(in section for $installable)",$weaker,
+                        $ARROW, $stronger,
+                        $prerequisite
+                    )if $relation->satisfies($prerequisite);
+                }
+            }
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Copyright.pm b/lib/Lintian/Check/Debian/Copyright.pm
new file mode 100644
index 0000000..6eb8900
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Copyright.pm
@@ -0,0 +1,586 @@
+# copyright -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2011 Jakub Wilk
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Copyright;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any all none uniq);
+use Path::Tiny;
+use Syntax::Keyword::Try;
+use Unicode::UTF8 qw(valid_utf8 decode_utf8 encode_utf8);
+
+use Lintian::Deb822;
+use Lintian::IPC::Run3 qw(safe_qx);
+use Lintian::Spelling qw(check_spelling);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+const my $APPROXIMATE_GPL_LENGTH => 12_000;
+const my $APPROXIMATE_GFDL_LENGTH => 12_000;
+const my $APPROXIMATE_APACHE_2_LENGTH => 10_000;
+
+sub spelling_tag_emitter {
+    my ($self, @orig_args) = @_;
+
+    return sub {
+        return $self->hint(@orig_args, @_);
+    };
+}
+
+sub source {
+    my ($self) = @_;
+
+    my $debian_dir = $self->processable->patched->resolve_path('debian/');
+    return
+      unless defined $debian_dir;
+
+    my @installables = $self->processable->debian_control->installables;
+    my @additional = map { $_ . '.copyright' } @installables;
+
+    my @candidates = ('copyright', @additional);
+    my @files = grep { defined } map { $debian_dir->child($_) } @candidates;
+
+    # look for <pkgname>.copyright for a single installable
+    if (@files == 1) {
+        my $single = $files[0];
+
+        $self->pointed_hint('named-copyright-for-single-installable',
+            $single->pointer)
+          unless $single->name eq 'debian/copyright';
+    }
+
+    $self->hint('no-debian-copyright-in-source')
+      unless @files;
+
+    my @symlinks = grep { $_->is_symlink } @files;
+    $self->pointed_hint('debian-copyright-is-symlink', $_->pointer)
+      for @symlinks;
+
+    return;
+}
+
+# no copyright in udebs
+sub binary {
+    my ($self) = @_;
+
+    my $package = $self->processable->name;
+
+    # looking up entry without slash first; index should not be so picky
+    my $doclink
+      = $self->processable->installed->lookup("usr/share/doc/$package");
+    if ($doclink && $doclink->is_symlink) {
+
+        # check if this symlink references a directory elsewhere
+        if ($doclink->link =~ m{^(?:\.\.)?/}s) {
+            $self->pointed_hint(
+                'usr-share-doc-symlink-points-outside-of-usr-share-doc',
+                $doclink->pointer, $doclink->link);
+            return;
+        }
+
+        # The symlink may point to a subdirectory of another
+        # /usr/share/doc directory.  This is allowed if this
+        # package depends on link and both packages come from the
+        # same source package.
+        #
+        # Policy requires that packages be built from the same
+        # source if they're going to do this, which by my (rra's)
+        # reading means that we should have a strict version
+        # dependency.  However, in practice the copyright file
+        # doesn't change a lot and strict version dependencies
+        # cause other problems (such as with arch: any / arch: all
+        # package combinations and binNMUs).
+        #
+        # We therefore just require the dependency for now and
+        # don't worry about the version number.
+        my $link = $doclink->link;
+        $link =~ s{/.*}{};
+
+        unless ($self->depends_on($self->processable, $link)) {
+            $self->hint('usr-share-doc-symlink-without-dependency', $link);
+
+            return;
+        }
+
+        # Check if the link points to a package from the same source.
+        $self->check_cross_link($link);
+
+        return;
+    }
+
+    # now with a slash; indicates directory
+    my $docdir
+      = $self->processable->installed->lookup("usr/share/doc/$package/");
+    unless ($docdir) {
+        $self->hint('no-copyright-file');
+        return;
+    }
+
+    my $found = 0;
+    my $zipped = $docdir->child('copyright.gz');
+    if (defined $zipped) {
+
+        $self->pointed_hint('copyright-file-compressed', $zipped->pointer);
+        $found = 1;
+    }
+
+    my $linked = 0;
+
+    my $item = $docdir->child('copyright');
+    if (defined $item) {
+        $found = 1;
+
+        if ($item->is_symlink) {
+
+            $self->pointed_hint('copyright-file-is-symlink', $item->pointer);
+            $linked = 1;
+         # fall through; coll/copyright-file prevents reading through evil link
+        }
+    }
+
+    unless ($found) {
+
+        # #522827: special exception for perl for now
+        $self->hint('no-copyright-file')
+          unless $package eq 'perl';
+
+        return;
+    }
+
+    my $copyrigh_path;
+
+    my $uncompressed
+      = $self->processable->installed->resolve_path(
+        "usr/share/doc/$package/copyright");
+    $copyrigh_path = $uncompressed->unpacked_path
+      if defined $uncompressed;
+
+    my $compressed
+      = $self->processable->installed->resolve_path(
+        "usr/share/doc/$package/copyright.gz");
+    if (defined $compressed) {
+
+        my $bytes = safe_qx('gunzip', '-c', $compressed->unpacked_path);
+        my $contents = decode_utf8($bytes);
+
+        my $extracted
+          = path($self->processable->basedir)->child('copyright')->stringify;
+        path($extracted)->spew($contents);
+
+        $copyrigh_path = $extracted;
+    }
+
+    return
+      unless length $copyrigh_path;
+
+    my $bytes = path($copyrigh_path)->slurp;
+
+    # another check complains about invalid encoding
+    return
+      unless valid_utf8($bytes);
+
+    # check contents of copyright file
+    my $contents = decode_utf8($bytes);
+
+    $self->hint('copyright-has-crs')
+      if $contents =~ /\r/;
+
+    my $wrong_directory_detected = 0;
+
+    my $KNOWN_COMMON_LICENSES
+      =  $self->data->load('copyright-file/common-licenses');
+
+    if ($contents =~ m{ (usr/share/common-licenses/ ( [^ \t]*? ) \.gz) }xsm) {
+        my ($path, $license) = ($1, $2);
+        if ($KNOWN_COMMON_LICENSES->recognizes($license)) {
+            $self->hint('copyright-refers-to-compressed-license', $path);
+        }
+    }
+
+    # Avoid complaining about referring to a versionless license file
+    # if the word "version" appears nowhere in the copyright file.
+    # This won't catch all of our false positives for GPL references
+    # that don't include a specific version number, but it will get
+    # the obvious ones.
+    if ($contents =~ m{(usr/share/common-licenses/(L?GPL|GFDL))([^-])}i) {
+        my ($ref, $license, $separator) = ($1, $2, $3);
+        if ($separator =~ /[\d\w]/) {
+            $self->hint('copyright-refers-to-nonexistent-license-file',
+                "$ref$separator");
+        } elsif ($contents =~ /\b(?:any|or)\s+later(?:\s+version)?\b/i
+            || $contents =~ /License: $license-[\d\.]+\+/i
+            || $contents =~ /as Perl itself/i
+            || $contents =~ /License-Alias:\s+Perl/
+            || $contents =~ /License:\s+Perl/) {
+            $self->hint('copyright-refers-to-symlink-license', $ref);
+        } else {
+            $self->hint('copyright-refers-to-versionless-license-file', $ref)
+              if $contents =~ /\bversion\b/;
+        }
+    }
+
+    # References to /usr/share/common-licenses/BSD are deprecated as of Policy
+    # 3.8.5.
+    if ($contents =~ m{/usr/share/common-licenses/BSD}) {
+        $self->hint('copyright-refers-to-deprecated-bsd-license-file');
+    }
+
+    if ($contents =~ m{(usr/share/common-licences)}) {
+        $self->hint('copyright-refers-to-incorrect-directory', $1);
+        $wrong_directory_detected = 1;
+    }
+
+    if ($contents =~ m{usr/share/doc/copyright}) {
+        $self->hint('copyright-refers-to-old-directory');
+        $wrong_directory_detected = 1;
+    }
+
+    if ($contents =~ m{usr/doc/copyright}) {
+        $self->hint('copyright-refers-to-old-directory');
+        $wrong_directory_detected = 1;
+    }
+
+    # Lame check for old FSF zip code.  Try to avoid false positives from other
+    # Cambridge, MA addresses.
+    if ($contents =~ m/(?:Free\s*Software\s*Foundation.*02139|02111-1307)/s) {
+        $self->hint('old-fsf-address-in-copyright-file');
+    }
+
+    # Whether the package is covered by the GPL, used later for the
+    # libssl check.
+    my $gpl;
+
+    if (
+        length $contents > $APPROXIMATE_GPL_LENGTH
+        && (
+            $contents =~ m{  \b \QGNU GENERAL PUBLIC LICENSE\E \s*
+                    \QTERMS AND CONDITIONS FOR COPYING,\E \s*
+                    \QDISTRIBUTION AND MODIFICATION\E \b }msx
+            || (
+                $contents =~ m{ \b \QGNU GENERAL PUBLIC LICENSE\E
+                                   \s* \QVersion 3\E }msx
+                && $contents =~ m{ \b \QTERMS AND CONDITIONS\E \s }msx
+            )
+        )
+    ) {
+        $self->hint('copyright-file-contains-full-gpl-license');
+        $gpl = 1;
+    }
+
+    if (
+        length $contents > $APPROXIMATE_GFDL_LENGTH
+        && $contents =~ m{ \b \QGNU Free Documentation License\E
+                           \s* \QVersion 1.2\E }msx
+        && $contents =~ m{ \b \Q1. APPLICABILITY AND DEFINITIONS\E }msx
+    ) {
+
+        $self->hint('copyright-file-contains-full-gfdl-license');
+    }
+
+    if (   length $contents > $APPROXIMATE_APACHE_2_LENGTH
+        && $contents =~ m{ \b \QApache License\E \s+ \QVersion 2.0,\E }msx
+        && $contents
+        =~ m{ \QTERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION\E }msx
+    ) {
+
+        $self->hint('copyright-file-contains-full-apache-2-license');
+    }
+
+    # wtf?
+    if (   ($contents =~ m{common-licenses(/\S+)})
+        && ($contents !~ m{/usr/share/common-licenses/})) {
+        $self->hint('copyright-does-not-refer-to-common-license-file', $1);
+    }
+
+    # This check is a bit prone to false positives, since some other
+    # licenses mention the GPL.  Also exclude any mention of the GPL
+    # following what looks like mail header fields, since sometimes
+    # e-mail discussions of licensing are included in the copyright
+    # file but aren't referring to the license of the package.
+    unless (
+        $contents =~ m{/usr/share/common-licenses}
+        || $contents =~ m/Zope Public License/
+        || $contents =~ m/LICENSE AGREEMENT FOR PYTHON 1.6.1/
+        || $contents =~ m/LaTeX Project Public License/
+        || $contents
+        =~ m/(?:^From:.*^To:|^To:.*^From:).*(?:GNU General Public License|GPL)/ms
+        || $contents =~ m/AFFERO GENERAL PUBLIC LICENSE/
+        || $contents =~ m/GNU Free Documentation License[,\s]*Version 1\.1/
+        || $contents =~ m/CeCILL FREE SOFTWARE LICENSE AGREEMENT/ #v2.0
+        || $contents =~ m/FREE SOFTWARE LICENSING AGREEMENT CeCILL/ #v1.1
+        || $contents =~ m/CNRI OPEN SOURCE GPL-COMPATIBLE LICENSE AGREEMENT/
+        || $contents =~ m/compatible\s+with\s+(?:the\s+)?(?:GNU\s+)?GPL/
+        || $contents =~ m/(?:GNU\s+)?GPL\W+compatible/
+        || $contents
+        =~ m/was\s+previously\s+(?:distributed\s+)?under\s+the\s+GNU/
+        || $contents
+        =~ m/means\s+either\s+the\s+GNU\s+General\s+Public\s+License/
+        || $wrong_directory_detected
+    ) {
+        if (
+            check_names_texts(
+                $contents,
+                qr/\b(?:GFDL|gnu[-_]free[-_]documentation[-_]license)\b/i,
+                qr/GNU Free Documentation License|(?-i:\bGFDL\b)/i
+            )
+        ) {
+            $self->hint('copyright-not-using-common-license-for-gfdl');
+        }elsif (
+            check_names_texts(
+                $contents,
+qr/\b(?:LGPL|gnu[-_](?:lesser|library)[-_]general[-_]public[-_]license)\b/i,
+qr/GNU (?:Lesser|Library) General Public License|(?-i:\bLGPL\b)/i
+            )
+        ) {
+            $self->hint('copyright-not-using-common-license-for-lgpl');
+        }elsif (
+            check_names_texts(
+                $contents,
+                qr/\b(?:GPL|gnu[-_]general[-_]public[-_]license)\b/i,
+                qr/GNU General Public License|(?-i:\bGPL\b)/i
+            )
+        ) {
+            $self->hint('copyright-not-using-common-license-for-gpl');
+            $gpl = 1;
+        }elsif (
+            check_names_texts(
+                $contents,qr/\bapache[-_]2/i,
+                qr/\bApache License\s*,?\s*Version 2|\b(?-i:Apache)-2/i
+            )
+        ) {
+            $self->hint('copyright-not-using-common-license-for-apache2');
+        }
+    }
+
+    if (
+        check_names_texts(
+            $contents,
+            qr/\b(?:perl|artistic)\b/,
+            sub {
+                my ($text) = @_;
+                $text
+                  =~ /(?:under )?(?:the )?(?:same )?(?:terms )?as Perl itself\b/i
+                  && $text !~ m{usr/share/common-licenses/};
+            }
+        )
+    ) {
+        $self->hint('copyright-file-lacks-pointer-to-perl-license');
+    }
+
+    # Checks for various packaging helper boilerplate.
+
+    $self->hint('helper-templates-in-copyright')
+      if $contents =~ m{<fill in (?:http/)?ftp site>}
+      || $contents =~ /<Must follow here>/
+      || $contents =~ /<Put the license of the package here/
+      || $contents =~ /<put author[\'\(]s\)? name and email here>/
+      || $contents =~ /<Copyright \(C\) YYYY Name OfAuthor>/
+      || $contents =~ /Upstream Author\(s\)/
+      || $contents =~ /<years>/
+      || $contents =~ /<special license>/
+      || $contents
+      =~ /<Put the license of the package here indented by 1 space>/
+      || $contents
+      =~ /<This follows the format of Description: lines\s*in control file>/
+      || $contents =~ /<Including paragraphs>/
+      || $contents =~ /<likewise for another author>/;
+
+    # dh-make-perl
+    $self->hint('copyright-contains-automatically-extracted-boilerplate')
+      if $contents =~ /This copyright info was automatically extracted/;
+
+    $self->hint('helper-templates-in-copyright')
+      if $contents =~ /<INSERT COPYRIGHT YEAR\(S\) HERE>/;
+
+    $self->hint('copyright-has-url-from-dh_make-boilerplate')
+      if $contents =~ m{url://};
+
+    # dh-make boilerplate
+    my @dh_make_boilerplate = (
+"# Please also look if there are files or directories which have a\n# different copyright/license attached and list them here.",
+"# If you want to use GPL v2 or later for the /debian/* files use\n# the following clauses, or change it to suit. Delete these two lines"
+    );
+
+    $self->hint('copyright-contains-dh_make-todo-boilerplate')
+      if any { $contents =~ /$_/ } @dh_make_boilerplate;
+
+    $self->hint('copyright-with-old-dh-make-debian-copyright')
+      if $contents =~ /The\s+Debian\s+packaging\s+is\s+\(C\)\s+\d+/i;
+
+    # Other flaws in the copyright phrasing or contents.
+    if ($found && !$linked) {
+        $self->hint('copyright-without-copyright-notice')
+          unless $contents
+          =~ m{(?:Copyright|Copr\.|\N{COPYRIGHT SIGN})(?:.*|[\(C\):\s]+)\b\d{4}\b
+               |\bpublic(?:\s+|-)domain\b}xi;
+    }
+
+    check_spelling(
+        $self->data,$contents,
+        $self->group->spelling_exceptions,
+        $self->spelling_tag_emitter('spelling-error-in-copyright'), 0
+    );
+
+    # Now, check for linking against libssl if the package is covered
+    # by the GPL.  (This check was requested by ftp-master.)  First,
+    # see if the package is under the GPL alone and try to exclude
+    # packages with a mix of GPL and LGPL or Artistic licensing or
+    # with an exception or exemption.
+    if (($gpl || $contents =~ m{/usr/share/common-licenses/GPL})
+        &&$contents
+        !~ m{exception|exemption|/usr/share/common-licenses/(?!GPL)\S}){
+
+        my @depends
+          = split(/\s*,\s*/,$self->processable->fields->value('Depends'));
+        my @predepends
+          = split(/\s*,\s*/,$self->processable->fields->value('Pre-Depends'));
+
+        $self->hint('possible-gpl-code-linked-with-openssl')
+          if any { /^libssl[0-9.]+(?:\s|\z)/ && !/\|/ }(@depends, @predepends);
+    }
+
+    return;
+} # </run>
+
+# -----------------------------------
+
+# Returns true if the package whose information is in $processable depends $package
+# or if $package is essential.
+sub depends_on {
+    my ($self, $processable, $package) = @_;
+
+    my $KNOWN_ESSENTIAL = $self->data->load('fields/essential');
+
+    return 1
+      if $KNOWN_ESSENTIAL->recognizes($package);
+
+    my $strong = $processable->relation('strong');
+    return 1
+      if $strong->satisfies($package);
+
+    my $arch = $processable->architecture;
+    return 1
+      if $arch ne 'all' and $strong->satisfies("${package}:${arch}");
+
+    return 0;
+}
+
+# Checks cross pkg links for /usr/share/doc/$pkg links
+sub check_cross_link {
+    my ($self, $foreign) = @_;
+
+    my $source = $self->group->source;
+    if ($source) {
+
+        # source package is available; check its list of binaries
+        return
+          if any { $foreign eq $_ } $source->debian_control->installables;
+
+        $self->hint('usr-share-doc-symlink-to-foreign-package', $foreign);
+
+    } else {
+        # The source package is not available, but the binary could
+        # be present anyway;  If they are in the same group, they claim
+        # to have the same source (and source version)
+        return
+          if any { $_->name eq $foreign }$self->group->get_installables;
+
+        # It was not, but since the source package was not present, we cannot
+        # tell if it is foreign or not at this point.
+
+        $self->hint(
+'cannot-check-whether-usr-share-doc-symlink-points-to-foreign-package'
+        );
+    }
+
+    return;
+}
+
+# Checks the name and text of every license in the file against given name and
+# text check coderefs, if the file is in the new format, if the file is in the
+# old format only runs the text coderef against the whole file.
+sub check_names_texts {
+    my ($contents, $name_check, $action) = @_;
+
+    my $text_check;
+
+    if ((ref($action) || $EMPTY) eq 'Regexp') {
+        $text_check = sub {
+            my ($textref) = @_;
+            return ${$textref} =~ $action;
+        };
+
+    } else {
+        $text_check = sub {
+            my ($textref) = @_;
+            return $action->(${$textref});
+        };
+    }
+
+    my $deb822 = Lintian::Deb822->new;
+
+    my @paragraphs;
+    try {
+        @paragraphs = $deb822->parse_string($contents);
+
+    } catch {
+        # parse error: copyright not in new format, just check text
+        return $text_check->(\$contents);
+    }
+
+    my @licenses = grep { length } map { $_->value('License') } @paragraphs;
+    for my $license (@licenses) {
+
+        my ($name, $text) = ($license =~ /^\s*([^\r\n]+)\r?\n(.*)\z/s);
+
+        next
+          unless length $text;
+
+        next
+          if $text =~ /^[\s\r\n]*\z/;
+
+        return 1
+          if $name =~ $name_check
+          && $text_check->(\$text);
+    }
+
+    # did not match anything
+    return 0;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Copyright/ApacheNotice.pm b/lib/Lintian/Check/Debian/Copyright/ApacheNotice.pm
new file mode 100644
index 0000000..72e91b4
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Copyright/ApacheNotice.pm
@@ -0,0 +1,105 @@
+# debian/copyright/apache-notice -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2011 Jakub Wilk
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Copyright::ApacheNotice;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SPACE => q{ };
+
+sub source {
+    my ($self) = @_;
+
+    my $debian_dir = $self->processable->patched->resolve_path('debian/');
+    return
+      unless defined $debian_dir;
+
+    my @installables = $self->processable->debian_control->installables;
+    my @additional = map { $_ . '.copyright' } @installables;
+
+    my @candidates = ('copyright', @additional);
+    my @files = grep { defined } map { $debian_dir->child($_) } @candidates;
+
+    # another check complains about legacy encoding, if needed
+    my @valid_utf8 = grep { $_->is_valid_utf8 } @files;
+
+    $self->check_apache_notice_files($_)for @valid_utf8;
+
+    return;
+}
+
+sub check_apache_notice_files {
+    my ($self, $file) = @_;
+
+    my $contents = $file->decoded_utf8;
+    return
+      unless $contents =~ /apache[-\s]+2\./i;
+
+    my @notice_files = grep {
+        $_->basename =~ /^NOTICE(\.txt)?$/
+          and $_->is_open_ok
+          and $_->bytes =~ /apache/i
+    } @{$self->processable->patched->sorted_list};
+    return
+      unless @notice_files;
+
+    my @binaries = grep { $_->type ne 'udeb' } $self->group->get_installables;
+    return
+      unless @binaries;
+
+    for my $binary (@binaries) {
+
+        # look at all path names in the package
+        my @names = map { $_->name } @{$binary->installed->sorted_list};
+
+        # and also those shipped in jars
+        my @jars = grep { scalar keys %{$_->java_info} }
+          @{$binary->installed->sorted_list};
+        push(@names, keys %{$_->java_info->{files}})for @jars;
+
+        return
+          if any { m{/NOTICE(\.txt)?(\.gz)?$} } @names;
+    }
+
+    $self->pointed_hint('missing-notice-file-for-apache-license', $_->pointer)
+      for @notice_files;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Copyright/Dep5.pm b/lib/Lintian/Check/Debian/Copyright/Dep5.pm
new file mode 100644
index 0000000..1084de8
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Copyright/Dep5.pm
@@ -0,0 +1,968 @@
+# debian/copyright/dep5 -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2011 Jakub Wilk
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Copyright::Dep5;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::Compare;
+use List::SomeUtils qw(any all none uniq);
+use Syntax::Keyword::Try;
+use Regexp::Wildcards;
+use Time::Piece;
+use XML::LibXML;
+
+use Lintian::Deb822;
+use Lintian::Relation::Version qw(versions_compare);
+use Lintian::Util qw(match_glob);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $LAST_SIGNIFICANT_DEP5_CHANGE => '0+svn~166';
+const my $LAST_DEP5_OVERHAUL => '0+svn~148';
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $COLON => q{:};
+const my $HYPHEN => q{-};
+const my $ASTERISK => q{*};
+
+const my $MINIMUM_CREATIVE_COMMMONS_LENGTH => 20;
+const my $LAST_ITEM => -1;
+
+const my %NEW_FIELD_NAMES        => (
+    'Format-Specification' => 'Format',
+    'Maintainer'           => 'Upstream-Contact',
+    'Upstream-Maintainer'  => 'Upstream-Contact',
+    'Contact'              => 'Upstream-Contact',
+    'Name'                 => 'Upstream-Name',
+);
+
+sub source {
+    my ($self) = @_;
+
+    my $debian_dir = $self->processable->patched->resolve_path('debian/');
+    return
+      unless defined $debian_dir;
+
+    my @installables = $self->processable->debian_control->installables;
+    my @additional = map { $_ . '.copyright' } @installables;
+
+    my @candidates = ('copyright', @additional);
+    my @files = grep { defined $_ && !$_->is_symlink }
+      map { $debian_dir->child($_) } @candidates;
+
+    # another check complains about legacy encoding, if needed
+    my @valid_utf8 = grep { $_->is_valid_utf8 } @files;
+
+    $self->check_dep5_copyright($_) for @valid_utf8;
+
+    return;
+}
+
+# The policy states, since 4.0.0, that people should use "https://" for the
+# format URI. This is checked later in check_dep5_copyright.
+# return undef is not dep5 and '' if unknown version
+sub find_dep5_version {
+    my ($self, $file, $original_uri) = @_;
+
+    my $uri = $original_uri;
+    my $version;
+
+    if ($uri =~ /\b(?:rev=REVISION|VERSIONED_FORMAT_URL)\b/) {
+
+        $self->pointed_hint('boilerplate-copyright-format-uri',
+            $file->pointer,$uri);
+        return undef;
+    }
+
+    if (
+        $uri =~ s{ https?://wiki\.debian\.org/
+                                Proposals/CopyrightFormat\b}{}xsm
+    ){
+        $version = '0~wiki';
+
+        $version = "$version~$1"
+          if $uri =~ /^\?action=recall&rev=(\d+)$/;
+
+        return $version;
+    }
+
+    if ($uri =~ m{^https?://dep(-team\.pages)?\.debian\.net/deps/dep5/?$}) {
+
+        $version = '0+svn';
+        return $version;
+    }
+
+    if (
+        $uri =~ s{\A https?://svn\.debian\.org/
+                                  wsvn/dep/web/deps/dep5\.mdwn\b}{}xsm
+    ){
+        $version = '0+svn';
+
+        $version = "$version~$1"
+          if $uri =~ /^\?(?:\S+[&;])?rev=(\d+)(?:[&;]\S+)?$/;
+
+        return $version;
+    }
+    if (
+        $uri =~ s{ \A https?://(?:svn|anonscm)\.debian\.org/
+                                    viewvc/dep/web/deps/dep5\.mdwn\b}{}xsm
+    ){
+        $version = '0+svn';
+        $uri =~ m{\A \? (?:\S+[&;])?
+                             (?:pathrev|revision|rev)=(\d+)(?:[&;]\S+)?
+                          \Z}xsm
+          and $version = "$version~$1";
+        return $version;
+    }
+    if (
+        $uri =~ m{ \A
+                       https?://www\.debian\.org/doc/
+                       (?:packaging-manuals/)?copyright-format/(\d+\.\d+)/?
+                   \Z}xsm
+    ){
+        $version = $1;
+        return $version;
+    }
+
+    $self->pointed_hint('unknown-copyright-format-uri',
+        $file->pointer, $original_uri);
+
+    return undef;
+}
+
+sub check_dep5_copyright {
+    my ($self, $copyright_file) = @_;
+
+    my $contents = $copyright_file->decoded_utf8;
+
+    if ($contents =~ /^Files-Excluded:/m) {
+
+        if ($contents
+            =~ m{^Format:.*/doc/packaging-manuals/copyright-format/1.0/?$}m) {
+
+            $self->pointed_hint('repackaged-source-not-advertised',
+                $copyright_file->pointer)
+              unless $self->processable->repacked
+              || $self->processable->native;
+
+        } else {
+            $self->pointed_hint('files-excluded-without-copyright-format-1.0',
+                $copyright_file->pointer);
+        }
+    }
+
+    unless (
+        $contents =~ m{
+               (?:^ | \n)
+               (?i: format(?: [:] |[-\s]spec) )
+               (?: . | \n\s+ )*
+               (?: /dep[5s]?\b | \bDEP ?5\b
+                 | [Mm]achine-readable\s(?:license|copyright)
+                 | /copyright-format/ | CopyrightFormat
+                 | VERSIONED_FORMAT_URL
+               ) }x
+    ){
+
+        $self->pointed_hint('no-dep5-copyright', $copyright_file->pointer);
+        return;
+    }
+
+    # get format before parsing as a debian control file
+    my $first_para = $contents;
+    $first_para =~ s/^#.*//mg;
+    $first_para =~ s/[ \t]+$//mg;
+    $first_para =~ s/^\n+//g;
+    $first_para =~ s/\n\n.*/\n/s;    #;; hi emacs
+    $first_para =~ s/\n?[ \t]+/ /g;
+
+    if ($first_para !~ /^Format(?:-Specification)?:\s*(\S+)\s*$/mi) {
+        $self->pointed_hint('unknown-copyright-format-uri',
+            $copyright_file->pointer);
+        return;
+    }
+
+    my $uri = $1;
+
+    # strip fragment identifier
+    $uri =~ s/^([^#\s]+)#/$1/;
+
+    my $version = $self->find_dep5_version($copyright_file, $uri);
+    return
+      unless defined $version;
+
+    if ($version =~ /wiki/) {
+        $self->pointed_hint('wiki-copyright-format-uri',
+            $copyright_file->pointer, $uri);
+
+    } elsif ($version =~ /svn$/) {
+        $self->pointed_hint('unversioned-copyright-format-uri',
+            $copyright_file->pointer, $uri);
+
+    } elsif (versions_compare($version, '<<', $LAST_SIGNIFICANT_DEP5_CHANGE)) {
+        $self->pointed_hint('out-of-date-copyright-format-uri',
+            $copyright_file->pointer, $uri);
+
+    } elsif ($uri =~ m{^http://www\.debian\.org/}) {
+        $self->pointed_hint('insecure-copyright-format-uri',
+            $copyright_file->pointer, $uri);
+    }
+
+    return
+      if versions_compare($version, '<<', $LAST_DEP5_OVERHAUL);
+
+    # probably DEP 5 format; let's try more checks
+    my $deb822 = Lintian::Deb822->new;
+
+    my @sections;
+    try {
+        @sections = $deb822->read_file($copyright_file->unpacked_path);
+
+    } catch {
+        my $error = $@;
+        chomp $error;
+        $error =~ s{^syntax error in }{};
+
+        $self->pointed_hint('syntax-error-in-dep5-copyright',
+            $copyright_file->pointer, $@);
+
+        return;
+    }
+
+    return
+      unless @sections;
+
+    my %found_standalone;
+    my %license_names_by_section;
+    my %license_text_by_section;
+    my %license_identifier_by_section;
+
+    my @license_sections = grep { $_->declares('License') } @sections;
+    for my $section (@license_sections) {
+
+        my $position = $section->position('License');
+        my $pointer = $copyright_file->pointer($position);
+
+        $self->pointed_hint('tab-in-license-text', $pointer)
+          if $section->untrimmed_value('License') =~ /\t/;
+
+        my ($anycase_identifier, $license_text)
+          = split(/\n/, $section->untrimmed_value('License'), 2);
+
+        $anycase_identifier //= $EMPTY;
+        $license_text //= $EMPTY;
+
+        # replace some weird characters
+        $anycase_identifier =~ s/[(),]/ /g;
+
+        # trim both ends
+        $anycase_identifier =~ s/^\s+|\s+$//g;
+        $license_text =~ s/^\s+|\s+$//g;
+
+        my $license_identifier = lc $anycase_identifier;
+
+        my @license_names
+          = grep { length } split(/\s+(?:and|or)\s+/, $license_identifier);
+
+        $license_names_by_section{$section->position} = \@license_names;
+        $license_text_by_section{$section->position} = $license_text;
+        $license_identifier_by_section{$section->position}
+          = $license_identifier;
+
+        $self->pointed_hint('empty-short-license-in-dep5-copyright', $pointer)
+          unless length $license_identifier;
+
+        $self->pointed_hint('pipe-symbol-used-as-license-disjunction',
+            $pointer, $license_identifier)
+          if $license_identifier =~ m{\s+\|\s+};
+
+        for my $name (@license_names) {
+            if ($name =~ /\s/) {
+
+                if($name =~ /[^ ]+ \s+ with \s+ (.*)/x) {
+
+                    my $exceptiontext = $1;
+
+                    $self->pointed_hint(
+                        'bad-exception-format-in-dep5-copyright',
+                        $pointer, $name)
+                      unless $exceptiontext =~ /[^ ]+ \s+ exception/x;
+
+                } else {
+
+                    $self->pointed_hint(
+                        'space-in-std-shortname-in-dep5-copyright',
+                        $pointer, $name);
+                }
+            }
+
+            $self->pointed_hint('invalid-short-name-in-dep5-copyright',
+                $pointer, $name)
+              if $name =~ m{^(?:agpl|gpl|lgpl)[^-]?\d(?:\.\d)?\+?$}
+              || $name =~ m{^bsd(?:[^-]?[234][^-]?(?:clause|cluase))?$};
+
+            $self->pointed_hint('license-problem-undefined-license',
+                $pointer, $name)
+              if $name eq $HYPHEN
+              || $name
+              =~ m{\b(?:fixmes?|todos?|undefined?|unknown?|unspecified)\b};
+        }
+
+        # stand-alone license
+        if (   length $license_identifier
+            && length $license_text
+            && !$section->declares('Files')) {
+
+            $found_standalone{$license_identifier} //= [];
+            push(@{$found_standalone{$license_identifier}}, $section);
+        }
+
+        if ($license_identifier =~ /^cc-/ && length $license_text) {
+
+            my $num_lines = $license_text =~ tr/\n//;
+
+            $self->pointed_hint('incomplete-creative-commons-license',
+                $pointer, $license_identifier)
+              if $num_lines < $MINIMUM_CREATIVE_COMMMONS_LENGTH;
+        }
+    }
+
+    my @not_unique
+      = grep { @{$found_standalone{$_}} > 1 } keys %found_standalone;
+    for my $name (@not_unique) {
+
+        next
+          if $name eq 'public-domain';
+
+        for my $section (@{$found_standalone{$name}}) {
+
+            my $position = $section->position('License');
+            my $pointer = $copyright_file->pointer($position);
+
+            $self->pointed_hint('dep5-copyright-license-name-not-unique',
+                $pointer, $name);
+        }
+    }
+
+    my ($header, @followers) = @sections;
+
+    my @obsolete_fields = grep { $header->declares($_) } keys %NEW_FIELD_NAMES;
+    for my $old_name (@obsolete_fields) {
+
+        my $position = $header->position($old_name);
+        my $pointer = $copyright_file->pointer($position);
+
+        $self->pointed_hint('obsolete-field-in-dep5-copyright',
+            $pointer, $old_name, $NEW_FIELD_NAMES{$old_name});
+    }
+
+    my $header_pointer = $copyright_file->pointer($header->position);
+
+    $self->pointed_hint('missing-field-in-dep5-copyright',
+        $header_pointer, 'Format')
+      if none { $header->declares($_) } qw(Format Format-Specification);
+
+    my $debian_control = $self->processable->debian_control;
+
+    $self->pointed_hint('missing-explanation-for-contrib-or-non-free-package',
+        $header_pointer)
+      if $debian_control->source_fields->value('Section')
+      =~ m{^(?:contrib|non-free)(?:/.+)?$}
+      && (none { $header->declares($_) } qw{Comment Disclaimer});
+
+    $self->pointed_hint('missing-explanation-for-repacked-upstream-tarball',
+        $header_pointer)
+      if $self->processable->repacked
+      && $header->value('Source') =~ m{^https?://}
+      && (none { $header->declares($_) } qw{Comment Files-Excluded});
+
+    my @ambiguous_sections = grep {
+        $_->declares('License')
+          && $_->declares('Copyright')
+          && !$_->declares('Files')
+    } @followers;
+
+    $self->pointed_hint(
+        'ambiguous-paragraph-in-dep5-copyright',
+        $copyright_file->pointer($_->position)
+    )for @ambiguous_sections;
+
+    my @unknown_sections
+      = grep {!$_->declares('License')&& !$_->declares('Files')} @followers;
+
+    $self->pointed_hint(
+        'unknown-paragraph-in-dep5-copyright',
+        $copyright_file->pointer($_->position)
+    )for @unknown_sections;
+
+    my @shipped_items;
+
+    if ($self->processable->native) {
+        @shipped_items = @{$self->processable->patched->sorted_list};
+
+    } else {
+        @shipped_items = @{$self->processable->orig->sorted_list};
+
+        # remove ./debian folder from orig, if any
+        @shipped_items = grep { !m{^debian/} } @shipped_items
+          if $self->processable->fields->value('Format') eq '3.0 (quilt)';
+
+        # add ./ debian folder from patched
+        my $debian_dir = $self->processable->patched->resolve_path('debian/');
+        push(@shipped_items, $debian_dir->descendants)
+          if $debian_dir;
+    }
+
+    my @shipped_names
+      = sort map { $_->name } grep { $_->is_file } @shipped_items;
+
+    my @excluded;
+    for my $wildcard ($header->trimmed_list('Files-Excluded')) {
+
+        my $position = $header->position('Files-Excluded');
+        my $pointer = $copyright_file->pointer($position);
+
+        my @offenders = escape_errors($wildcard);
+
+        $self->pointed_hint('invalid-escape-sequence-in-dep5-copyright',
+            $pointer, '(Files-Excluded)', $_)
+          for @offenders;
+
+        next
+          if @offenders;
+
+        # also match dir/filename for Files-Excluded: dir
+        unless ($wildcard =~ /\*/ || $wildcard =~ /\?/) {
+
+            my $candidate = $wildcard;
+            $candidate .= $SLASH
+              unless $candidate =~ m{/$};
+
+            my $item = $self->processable->orig->lookup($candidate);
+
+            $wildcard = $candidate . $ASTERISK
+              if defined $item && $item->is_dir;
+        }
+
+        my @match = match_glob($wildcard, @shipped_names);
+
+        # do not flag missing matches; uscan already excluded them
+        push(@excluded, @match);
+    }
+
+    my @included;
+    for my $wildcard ($header->trimmed_list('Files-Included')) {
+
+        my $position = $header->position('Files-Included');
+        my $pointer = $copyright_file->pointer($position);
+
+        my @offenders = escape_errors($wildcard);
+
+        $self->pointed_hint('invalid-escape-sequence-in-dep5-copyright',
+            $pointer, '(Files-Included)', $_)
+          for @offenders;
+
+        next
+          if @offenders;
+
+        # also match dir/filename for Files-Excluded: dir
+        unless ($wildcard =~ /\*/ || $wildcard =~ /\?/) {
+
+            my $candidate = $wildcard;
+            $candidate .= $SLASH
+              unless $candidate =~ m{/$};
+
+            my $item = $self->processable->orig->lookup($candidate);
+
+            $wildcard = $candidate . $ASTERISK
+              if defined $item && $item->is_dir;
+        }
+
+        my @match = match_glob($wildcard, @shipped_names);
+
+        $self->pointed_hint(
+            'superfluous-file-pattern', $pointer,
+            '(Files-Included)', $wildcard
+        )unless @match;
+
+        push(@included, @match);
+    }
+
+    my $lc = List::Compare->new(\@included, \@excluded);
+    my @affirmed = $lc->get_Lonly;
+    my @unwanted = $lc->get_Ronly;
+
+    # already unique
+    for my $name (@affirmed) {
+
+        my $position = $header->position('Files-Included');
+        my $pointer = $copyright_file->pointer($position);
+
+        $self->pointed_hint('file-included-already', $pointer, $name);
+    }
+
+    # already unique
+    for my $name (@unwanted) {
+
+        my $position = $header->position('Files-Excluded');
+        my $pointer = $copyright_file->pointer($position);
+
+        $self->pointed_hint('source-ships-excluded-file',$pointer, $name)
+          unless $name =~ m{^(?:debian|\.pc)/};
+    }
+
+    my @notice_names= grep { m{(^|/)(COPYING[^/]*|LICENSE)$} } @shipped_names;
+    my @quilt_names = grep { m{^\.pc/} } @shipped_names;
+
+    my @names_with_comma = grep { /,/ } @shipped_names;
+    my @fields_with_comma = grep { $_->value('Files') =~ /,/ } @followers;
+
+    for my $section (@fields_with_comma) {
+
+        my $position = $section->position('Files');
+        my $pointer = $copyright_file->pointer($position);
+
+        $self->pointed_hint('comma-separated-files-in-dep5-copyright',$pointer)
+          if !@names_with_comma;
+    }
+
+    # only attempt to evaluate globbing if commas could be legal
+    my $check_wildcards = !@fields_with_comma || @names_with_comma;
+
+    my @files_sections = grep {$_->declares('Files')} @followers;
+
+    for my $section (@files_sections) {
+
+        if (!length $section->value('Files')) {
+
+            my $position = $section->position('Files');
+            my $pointer = $copyright_file->pointer($position);
+
+            $self->pointed_hint('missing-field-in-dep5-copyright',
+                $pointer,'(empty field)', 'Files');
+        }
+
+        my $section_pointer = $copyright_file->pointer($section->position);
+
+        $self->pointed_hint('missing-field-in-dep5-copyright',
+            $section_pointer, 'License')
+          if !$section->declares('License');
+
+        $self->pointed_hint('missing-field-in-dep5-copyright',
+            $section_pointer, 'Copyright')
+          if !$section->declares('Copyright');
+
+        if ($section->declares('Copyright')
+            && !length $section->value('Copyright')) {
+
+            my $position = $section->position('Copyright');
+            my $pointer = $copyright_file->pointer($position);
+
+            $self->pointed_hint('missing-field-in-dep5-copyright',
+                $pointer, '(empty field)', 'Copyright');
+        }
+    }
+
+    my %sections_by_wildcard;
+    my %wildcard_by_file;
+    my %required_standalone;
+    my %positions_by_debian_year;
+    my @redundant_wildcards;
+
+    my $section_count = 0;
+    for my $section (@followers) {
+
+        my $wildcard_pointer
+          = $copyright_file->pointer($section->position('Files'));
+
+        my $copyright_pointer
+          = $copyright_file->pointer($section->position('Copyright'));
+
+        my $license_pointer
+          = $copyright_file->pointer($section->position('License'));
+
+        my @license_names
+          = @{$license_names_by_section{$section->position} // []};
+        my $license_text = $license_text_by_section{$section->position};
+
+        if ($section->declares('Files') && !length $license_text) {
+            $required_standalone{$_} = $section for @license_names;
+        }
+
+        my @wildcards;
+
+        # If it is the first paragraph, it might be an instance of
+        # the (no-longer) optional "first Files-field".
+        if (   $section_count == 0
+            && $section->declares('License')
+            && $section->declares('Copyright')
+            && !$section->declares('Files')) {
+
+            @wildcards = ($ASTERISK);
+
+        } else {
+            @wildcards = $section->trimmed_list('Files');
+        }
+
+        my @rightholders = $section->trimmed_list('Copyright', qr{ \n }x);
+        my @years = map { /(\d{4})/g } @rightholders;
+
+        if (any { m{^ debian (?: / | $) }x } @wildcards) {
+
+            my $position = $section->position('Copyright');
+
+            push(@{$positions_by_debian_year{$_}}, $position)for @years;
+        }
+
+        for my $wildcard (@wildcards) {
+            $sections_by_wildcard{$wildcard} //= [];
+            push(@{$sections_by_wildcard{$wildcard}}, $section);
+        }
+
+        $self->pointed_hint(
+            'global-files-wildcard-not-first-paragraph-in-dep5-copyright',
+            $wildcard_pointer)
+          if (any { $_ eq $ASTERISK } @wildcards) && $section_count > 0;
+
+        # stand-alone license paragraph
+        $self->pointed_hint('missing-license-text-in-dep5-copyright',
+            $license_pointer, $section->untrimmed_value('License'))
+          if !@wildcards
+          && $section->declares('License')
+          && !length $license_text;
+
+        next
+          unless $check_wildcards;
+
+        my %wildcards_same_section_by_file;
+
+        for my $wildcard (@wildcards) {
+
+            my @offenders = escape_errors($wildcard);
+
+            $self->pointed_hint('invalid-escape-sequence-in-dep5-copyright',
+                $wildcard_pointer, $_)
+              for @offenders;
+
+            next
+              if @offenders;
+
+            my @covered = match_glob($wildcard, @shipped_names);
+
+            for my $name (@covered) {
+                $wildcards_same_section_by_file{$name} //= [];
+                push(@{$wildcards_same_section_by_file{$name}}, $wildcard);
+            }
+        }
+
+        my @overwritten = grep { length $wildcard_by_file{$_} }
+          keys %wildcards_same_section_by_file;
+
+        for my $name (@overwritten) {
+
+            my $winning_wildcard
+              = @{$wildcards_same_section_by_file{$name}}[$LAST_ITEM];
+            my $loosing_wildcard = $wildcard_by_file{$name};
+
+            my $winner_depth = ($winning_wildcard =~ tr{/}{});
+            my $looser_depth = ($loosing_wildcard =~ tr{/}{});
+
+            $self->pointed_hint('globbing-patterns-out-of-order',
+                $wildcard_pointer,$loosing_wildcard, $winning_wildcard, $name)
+              if $looser_depth > $winner_depth;
+        }
+
+        # later matches have precendence; depends on section ordering
+        $wildcard_by_file{$_}
+          = @{$wildcards_same_section_by_file{$_}}[$LAST_ITEM]
+          for keys %wildcards_same_section_by_file;
+
+        my @overmatched_same_section
+          = grep { @{$wildcards_same_section_by_file{$_}} > 1 }
+          keys %wildcards_same_section_by_file;
+
+        for my $file (@overmatched_same_section) {
+
+            my $patterns
+              = join($SPACE, sort @{$wildcards_same_section_by_file{$file}});
+
+            $self->pointed_hint('redundant-globbing-patterns',
+                $wildcard_pointer,"($patterns) for $file");
+        }
+
+        push(@redundant_wildcards,
+            map { @{$wildcards_same_section_by_file{$_}} }
+              @overmatched_same_section);
+
+    } continue {
+        $section_count++;
+    }
+
+    my @debian_years = keys %positions_by_debian_year;
+    my @changelog_entries = @{$self->processable->changelog->entries};
+
+    if (@debian_years && @changelog_entries) {
+
+        my @descending = reverse sort { $a <=> $b } @debian_years;
+        my $most_recent_copyright = $descending[0];
+
+        my $tp = Time::Piece->strptime($changelog_entries[0]->Date,
+            '%a, %d %b %Y %T %z');
+        my $most_recent_changelog = $tp->year;
+
+        my @candidates = @{$positions_by_debian_year{$most_recent_copyright}};
+        my @sorted = sort { $a <=> $b } @candidates;
+
+        # pick the topmost, which should be the broadest pattern
+        my $position = $candidates[0];
+
+        $self->pointed_hint('update-debian-copyright',
+            $copyright_file->pointer($position),
+            $most_recent_copyright, 'vs', $most_recent_changelog)
+          if $most_recent_copyright < $most_recent_changelog;
+    }
+
+    if ($check_wildcards) {
+
+        my @duplicate_wildcards= grep { @{$sections_by_wildcard{$_}} > 1 }
+          keys %sections_by_wildcard;
+
+        for my $wildcard (@duplicate_wildcards) {
+
+            my $lines = join($SPACE,
+                map { $_->position('Files') }
+                  @{$sections_by_wildcard{$wildcard}});
+
+            $self->pointed_hint('duplicate-globbing-patterns',
+                $copyright_file->pointer,$wildcard, "(lines $lines)");
+        }
+
+        # do not issue next tag for duplicates or redundant wildcards
+        my $wildcard_lc = List::Compare->new(
+            [keys %sections_by_wildcard],
+            [
+                (
+                    values %wildcard_by_file, @duplicate_wildcards,
+                    @redundant_wildcards
+                )
+            ]
+        );
+        my @matches_nothing = $wildcard_lc->get_Lonly;
+
+        for my $wildcard (@matches_nothing) {
+            for my $section (@{$sections_by_wildcard{$wildcard}}) {
+
+                my $position = $section->position('Files');
+                my $pointer = $copyright_file->pointer($position);
+
+                $self->pointed_hint('superfluous-file-pattern', $pointer,
+                    $wildcard);
+            }
+        }
+
+        my %sections_by_file;
+        for my $name (keys %wildcard_by_file) {
+
+            $sections_by_file{$name} //= [];
+            my $wildcard = $wildcard_by_file{$name};
+
+            push(
+                @{$sections_by_file{$name}},
+                @{$sections_by_wildcard{$wildcard}}
+            );
+        }
+
+        my %license_identifiers_by_file;
+        for my $name (keys %sections_by_file) {
+
+            $license_identifiers_by_file{$name} //= [];
+
+            push(
+                @{$license_identifiers_by_file{$name}},
+                $license_identifier_by_section{$_->position}
+            ) for @{$sections_by_file{$name}};
+        }
+
+        my @xml_searchspace = keys %license_identifiers_by_file;
+
+        # do not examine Lintian's test suite for appstream metadata
+        @xml_searchspace = grep { !m{t/} } @xml_searchspace
+          if $self->processable->name eq 'lintian';
+
+        for my $name (@xml_searchspace) {
+
+            next
+              if $name =~ '^\.pc/';
+
+            next
+              unless $name =~ /\.xml$/;
+
+            my $parser = XML::LibXML->new;
+            $parser->set_option('no_network', 1);
+
+            my $file = $self->processable->patched->resolve_path($name);
+            my $doc;
+            try {
+                $doc = $parser->parse_file($file->unpacked_path);
+
+            } catch {
+                next;
+            }
+
+            next
+              unless $doc;
+
+            my @nodes = $doc->findnodes('/component/metadata_license');
+            next
+              unless @nodes;
+
+            # take first one
+            my $first = $nodes[0];
+            next
+              unless $first;
+
+            my $seen = lc($first->firstChild->data // $EMPTY);
+            next
+              unless $seen;
+
+            # Compare and also normalize the seen and wanted license
+            # identifier wrt. to redundant trailing dot-zeros,
+            # -or-later suffix vs + suffix, -only suffix vs no
+            # suffix. Still display the original variant in the tag.
+            my $seen_normalized = $seen;
+            $seen_normalized = 'expat' if $seen_normalized eq 'mit';
+            $seen_normalized =~ s/-or-later$/+/i;
+            $seen_normalized =~ s/-only$//i;
+            my $seen_nozero = $seen_normalized;
+            $seen_nozero =~ s/\.0//g;
+
+            my @wanted = @{$license_identifiers_by_file{$name}};
+            my @mismatched = grep {
+                my $want = $_;
+                my $want_normalized = $want;
+                $want_normalized = 'expat' if $want_normalized eq 'mit';
+                $want_normalized =~ s/-or-later$/+/i;
+                $want_normalized =~ s/-only$//i;
+                my $want_nozero = $want_normalized;
+                $want_nozero =~ s/\.0//g;
+
+                $want_normalized ne $seen_normalized
+                  and $want_nozero ne $seen_normalized
+                  and $want_normalized ne $seen_nozero
+                  and $want_nozero ne $seen_nozero;
+            } @wanted;
+
+            $self->pointed_hint('inconsistent-appstream-metadata-license',
+                $copyright_file->pointer, $name, "($seen != $_)")
+              for @mismatched;
+        }
+
+        my @no_license_needed = (@quilt_names, @notice_names);
+        my $unlicensed_lc
+          = List::Compare->new(\@shipped_names, \@no_license_needed);
+        my @license_needed = $unlicensed_lc->get_Lonly;
+
+        my @not_covered
+          = grep { !@{$sections_by_file{$_} // []} } @license_needed;
+
+        $self->pointed_hint('file-without-copyright-information',
+            $copyright_file->pointer, $_)
+          for @not_covered;
+    }
+
+    my $standalone_lc= List::Compare->new([keys %required_standalone],
+        [keys %found_standalone]);
+    my @missing_standalone = $standalone_lc->get_Lonly;
+    my @matched_standalone = $standalone_lc->get_intersection;
+    my @unused_standalone = $standalone_lc->get_Ronly;
+
+    for my $license (@missing_standalone) {
+
+        my $section = $required_standalone{$license};
+
+        my $position = $section->position('License');
+        my $pointer = $copyright_file->pointer($position);
+
+        $self->pointed_hint('missing-license-paragraph-in-dep5-copyright',
+            $pointer, $license);
+    }
+
+    for my $license (grep { $_ ne 'public-domain' } @unused_standalone) {
+
+        for my $section (@{$found_standalone{$license}}) {
+
+            my $position = $section->position('License');
+            my $pointer = $copyright_file->pointer($position);
+
+            $self->pointed_hint('unused-license-paragraph-in-dep5-copyright',
+                $pointer, $license);
+        }
+    }
+
+    for my $license (@matched_standalone) {
+
+        my $section = $required_standalone{$license};
+
+        my $position = $section->position('Files');
+        my $pointer = $copyright_file->pointer($position);
+
+        $self->pointed_hint('dep5-file-paragraph-references-header-paragraph',
+            $pointer, $license)
+          if all { $_ == $header } @{$found_standalone{$license}};
+    }
+
+    # license files do not require their own entries in d/copyright.
+    my $license_lc
+      = List::Compare->new(\@notice_names, [keys %sections_by_wildcard]);
+    my @listed_licenses = $license_lc->get_intersection;
+
+    $self->pointed_hint('license-file-listed-in-debian-copyright',
+        $copyright_file->pointer, $_)
+      for @listed_licenses;
+
+    return;
+}
+
+sub escape_errors {
+    my ($escaped) = @_;
+
+    my @sequences = ($escaped =~ m{\\.?}g);
+    my @illegal = grep { !m{^\\[*?]$} } @sequences;
+
+    return @illegal;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Copyright/Dep5/Components.pm b/lib/Lintian/Check/Debian/Copyright/Dep5/Components.pm
new file mode 100644
index 0000000..453a40b
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Copyright/Dep5/Components.pm
@@ -0,0 +1,109 @@
+# debian/copyright/dep5/components -- lintian check script -*- perl -*-
+
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Copyright::Dep5::Components;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::Compare;
+use Syntax::Keyword::Try;
+
+use Lintian::Deb822;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $debian_dir = $self->processable->patched->resolve_path('debian/');
+    return
+      unless defined $debian_dir;
+
+    my @installables = $self->processable->debian_control->installables;
+    my @additional = map { $_ . '.copyright' } @installables;
+
+    my @candidates = ('copyright', @additional);
+    my @files = grep { defined $_ && !$_->is_symlink }
+      map { $debian_dir->child($_) } @candidates;
+
+    # another check complains about legacy encoding, if needed
+    my @valid_utf8 = grep { $_->is_valid_utf8 } @files;
+
+    $self->check_dep5_copyright($_) for @valid_utf8;
+
+    return;
+}
+
+sub check_dep5_copyright {
+    my ($self, $copyright_file) = @_;
+
+    my $deb822 = Lintian::Deb822->new;
+
+    my @sections;
+    try {
+        @sections = $deb822->read_file($copyright_file->unpacked_path);
+
+    } catch {
+        # may not be in DEP 5 format
+        return;
+    }
+
+    return
+      unless @sections;
+
+    my ($header, @followers) = @sections;
+
+    my @initial_path_components;
+
+    for my $section (@followers) {
+
+        my @subdirs = $section->trimmed_list('Files');
+        s{ / .* $}{}x for @subdirs;
+
+        my @definite = grep { !/[*?]/ } @subdirs;
+
+        push(@initial_path_components, grep { length } @definite);
+    }
+
+    my @extra_source_components
+      = grep { length } values %{$self->processable->components};
+    my $component_lc = List::Compare->new(\@extra_source_components,
+        \@initial_path_components);
+
+    my @missing_components = $component_lc->get_Lonly;
+
+    $self->pointed_hint('add-component-copyright', $copyright_file->pointer,$_)
+      for @missing_components;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Debconf.pm b/lib/Lintian/Check/Debian/Debconf.pm
new file mode 100644
index 0000000..6b86bf9
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Debconf.pm
@@ -0,0 +1,794 @@
+# debian/debconf -- lintian check script -*- perl -*-
+
+# Copyright (C) 2001 Colin Watson
+# Copyright (C) 2020-21 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Debconf;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(none);
+use Path::Tiny;
+use Syntax::Keyword::Try;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Deb822;
+use Lintian::Deb822::Constants qw(DCTRL_DEBCONF_TEMPLATE);
+use Lintian::Relation;
+use Lintian::Util qw($PKGNAME_REGEX);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+
+const my $MAXIMUM_TEMPLATE_SYNOPSIS => 75;
+const my $MAXIMUM_LINE_LENGTH => 80;
+const my $MAXIMUM_LINES => 20;
+const my $ITEM_NOT_FOUND => -1;
+
+# From debconf-devel(7), section 'THE TEMPLATES FILE', up to date with debconf
+# version 1.5.24.  Added indices for cdebconf (indicates sort order for
+# choices); debconf doesn't support it, but it ignores it, which is safe
+# behavior. Likewise, help is supported as of cdebconf 0.143 but is not yet
+# supported by debconf.
+my %template_fields
+  = map { $_ => 1 } qw(Template Type Choices Indices Default Description Help);
+
+# From debconf-devel(7), section 'THE TEMPLATES FILE', up to date with debconf
+# version 1.5.24.
+my %valid_types = map { $_ => 1 } qw(
+  string
+  password
+  boolean
+  select
+  multiselect
+  note
+  error
+  title
+  text);
+
+# From debconf-devel(7), section 'THE DEBCONF PROTOCOL' under 'INPUT', up to
+# date with debconf version 1.5.24.
+my %valid_priorities = map { $_ => 1 } qw(low medium high critical);
+
+# All the packages that provide debconf functionality.  Anything using debconf
+# needs to have dependencies that satisfy one of these.
+my $ANY_DEBCONF = Lintian::Relation->new->load(
+    join(
+        ' | ', qw(debconf debconf-2.0 cdebconf
+          cdebconf-udeb libdebconfclient0 libdebconfclient0-udeb)
+    )
+);
+
+sub source {
+    my ($self) = @_;
+
+    my @catalogs= (
+        'templates',
+        map { "$_.templates" }$self->processable->debian_control->installables
+    );
+    my @files = grep { defined }
+      map { $self->processable->patched->resolve_path("debian/$_") } @catalogs;
+
+    my @utf8 = grep { $_->is_valid_utf8 and $_->is_file } @files;
+    for my $item (@utf8) {
+
+        my $deb822 = Lintian::Deb822->new;
+
+        my @templates;
+        try {
+            @templates
+              = $deb822->read_file($item->unpacked_path,
+                DCTRL_DEBCONF_TEMPLATE);
+
+        } catch {
+            my $error = $@;
+            chomp $error;
+            $error =~ s{^syntax error in }{};
+
+            $self->pointed_hint('syntax-error-in-debconf-template',
+                $item->pointer, $error);
+
+            next;
+        }
+
+        my @unsplit_choices
+          = grep {$_->declares('Template') && $_->declares('_Choices')}
+          @templates;
+
+        $self->pointed_hint(
+            'template-uses-unsplit-choices',
+            $item->pointer($_->position('_Choices')),
+            $_->value('Template')
+        )for @unsplit_choices;
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $usespreinst;
+    my $preinst = $self->processable->control->lookup('preinst');
+
+    if ($preinst and $preinst->is_file and $preinst->is_open_ok) {
+
+        open(my $fd, '<', $preinst->unpacked_path)
+          or die encode_utf8('Cannot open ' . $preinst->unpacked_path);
+
+        while (my $line = <$fd>) {
+            $line =~ s/\#.*//;    # Not perfect for Perl, but should be OK
+
+            if (   $line =~ m{/usr/share/debconf/confmodule}
+                || $line =~ /(?:Debconf|Debian::DebConf)::Client::ConfModule/){
+                $usespreinst=1;
+
+                last;
+            }
+        }
+        close($fd);
+    }
+
+    my $seenconfig;
+    my $ctrl_config = $self->processable->control->lookup('config');
+    if (defined $ctrl_config && $ctrl_config->is_file) {
+
+        $self->pointed_hint('debconf-config-not-executable',
+            $ctrl_config->pointer)
+          unless $ctrl_config->is_executable;
+
+        $seenconfig = 1;
+    }
+
+    my $seentemplates;
+    my $ctrl_templates = $self->processable->control->lookup('templates');
+    $seentemplates = 1 if $ctrl_templates and $ctrl_templates->is_file;
+
+    # This still misses packages that use debconf only in the postrm.
+    # Packages that ask debconf questions in the postrm should load
+    # the confmodule in the postinst so that debconf can register
+    # their templates.
+    return
+      unless $seenconfig
+      or $seentemplates
+      or $usespreinst;
+
+    # parse depends info for later checks
+
+    # Consider every package to depend on itself.
+    my $selfrel;
+    if ($self->processable->fields->declares('Version')) {
+        my $version = $self->processable->fields->value('Version');
+        $selfrel = $self->processable->name . " (= $version)";
+    } else {
+        $selfrel = $self->processable->name;
+    }
+
+    # Include self and provides as a package providing debconf presumably
+    # satisfies its own use of debconf (if any).
+    my $selfrelation
+      = $self->processable->relation('Provides')->logical_and($selfrel);
+    my $alldependencies
+      = $self->processable->relation('strong')->logical_and($selfrelation);
+
+    # See if the package depends on dbconfig-common.  Packages that do
+    # are allowed to have a config file with no templates, since they
+    # use the dbconfig-common templates.
+    my $usesdbconfig = $alldependencies->satisfies('dbconfig-common');
+
+    # Check that both debconf control area files are present.
+    if ($seenconfig and not $seentemplates and not $usesdbconfig) {
+
+        $self->hint('no-debconf-templates');
+
+    } elsif ($seentemplates
+        and not $seenconfig
+        and not $usespreinst
+        and $self->processable->type ne 'udeb') {
+
+        $self->hint('no-debconf-config');
+    }
+
+    # Lots of template checks.
+
+    my @templates;
+    if ($seentemplates) {
+
+        if ($ctrl_templates->is_valid_utf8) {
+            my $deb822 = Lintian::Deb822->new;
+
+            try {
+                # $seentemplates (above) will be false if $ctrl_templates is a
+                # symlink or not a file, so this should be safe without
+                # (re-checking) with -f/-l.
+                @templates= $deb822->read_file($ctrl_templates->unpacked_path,
+                    DCTRL_DEBCONF_TEMPLATE);
+
+            } catch {
+                my $error = $@;
+                chomp $error;
+                $error =~ s{^syntax error in }{};
+
+                $self->pointed_hint('syntax-error-in-debconf-template',
+                    $ctrl_templates->pointer, $error);
+
+                @templates = ();
+            }
+        }
+    }
+
+    my %template_by_name;
+    my %potential_db_abuse;
+    for my $template (@templates) {
+
+        my $isselect = $EMPTY;
+        my $name = $template->value('Template');
+
+        if (!$template->declares('Template')) {
+            $self->pointed_hint('no-template-name',
+                $ctrl_templates->pointer($template->position));
+            $name = 'no-template-name';
+
+        } else {
+            $template_by_name{$name} = $template;
+
+            $self->pointed_hint('malformed-template-name',
+                $ctrl_templates->pointer($template->position('Template')),
+                $name)
+              unless $name =~ m{[A-Za-z0-9.+-](?:/[A-Za-z0-9.+-])};
+        }
+
+        my $type = $template->value('Type');
+        if (!$template->declares('Type')) {
+
+            $self->pointed_hint('no-template-type',
+                $ctrl_templates->pointer($template->position), $name);
+
+        } elsif (!$valid_types{$type}) {
+
+            # cdebconf has a special "entropy" type
+            $self->pointed_hint('unknown-template-type',
+                $ctrl_templates->pointer($template->position('Type')), $type)
+              unless $type eq 'entropy'
+              && $alldependencies->satisfies('cdebconf');
+
+        } elsif ($type eq 'select' || $type eq 'multiselect') {
+            $isselect = 1;
+
+        } elsif ($type eq 'boolean') {
+
+            my $default = $template->value('Default');
+
+            $self->pointed_hint(
+                'boolean-template-has-bogus-default',
+                $ctrl_templates->pointer($template->position('Default')),
+                $name, $default
+              )
+              if $template->declares('Default')
+              && (none { $default eq $_ } qw(true false));
+        }
+
+        my $choices = $template->value('Choices');
+        if ($template->declares('Choices') && $choices !~ /^\s*$/) {
+
+            my $nrchoices = count_choices($choices);
+            for my $key ($template->names) {
+
+                if ($key =~ /^Choices-/) {
+                    my $translated = $template->value($key);
+
+                    if (!length($translated) || $translated =~ /^\s*$/){
+                        $self->pointed_hint(
+                            'empty-translated-choices',
+                            $ctrl_templates->pointer(
+                                $template->position('Choices')
+                            ),
+                            $name, $key
+                        );
+                    }
+
+                    if (count_choices($translated) != $nrchoices) {
+                        $self->pointed_hint(
+                            'mismatch-translated-choices',
+                            $ctrl_templates->pointer(
+                                $template->position('Choices')
+                            ),
+                            $name,$key
+                        );
+                    }
+                }
+            }
+
+            $self->pointed_hint('select-with-boolean-choices',
+                $ctrl_templates->pointer($template->position('Choices')),$name)
+              if $choices =~ /^\s*(yes\s*,\s*no|no\s*,\s*yes)\s*$/i;
+        }
+
+        $self->pointed_hint('select-without-choices',
+            $ctrl_templates->pointer($template->position), $name)
+          if $isselect && !$template->declares('Choices');
+
+        my $description = $template->value('Description');
+
+        $self->pointed_hint('no-template-description',
+            $ctrl_templates->pointer($template->position), $name)
+          unless length $description
+          || length $template->value('_Description');
+
+        if ($description =~ /^\s*(.*?)\s*?\n\s*\1\s*$/){
+
+            # Check for duplication. Should all this be folded into the
+            # description checks?
+            $self->pointed_hint('duplicate-long-description-in-template',
+                $ctrl_templates->pointer($template->position('Description')),
+                $name);
+        }
+
+        my %languages;
+        for my $field ($template->names) {
+            # Tests on translations
+            my ($mainfield, $lang) = split m/-/, $field, 2;
+            if (defined $lang) {
+                $languages{$lang}{$mainfield}=1;
+            }
+            my $stripped = $mainfield;
+            $stripped =~ s/^_//;
+            unless ($template_fields{$stripped}) {
+                # Ignore language codes here
+                $self->pointed_hint('unknown-field-in-templates',
+                    $ctrl_templates->pointer($template->position($field)),
+                    $name, $field);
+            }
+        }
+
+        if (length $name && length $type) {
+            $potential_db_abuse{$name} = 1
+              if $type eq 'note' || $type eq 'text';
+        }
+
+        # Check the description against the best practices in the
+        # Developer's Reference, but skip all templates where the
+        # short description contains the string "for internal use".
+        my ($short, $extended);
+        if (length $description) {
+            ($short, $extended) = split(/\n/, $description, 2);
+            unless (defined $short) {
+                $short = $description;
+                $extended = $EMPTY;
+            }
+        } else {
+            $short = $EMPTY;
+            $extended = $EMPTY;
+        }
+
+        my $ttype = $type;
+        unless ($short =~ /for internal use/i) {
+
+            my $pointer
+              = $ctrl_templates->pointer($template->position('Description'));
+
+            my $isprompt = grep { $_ eq $ttype } qw(string password);
+            if ($isprompt) {
+                if (
+                    $short
+                    && (   $short !~ m/:$/
+                        || $short =~ m/^(what|who|when|where|which|how)/i)
+                ) {
+                    $self->pointed_hint('malformed-prompt-in-templates',
+                        $pointer, $name);
+                }
+            }
+            if ($isselect) {
+                if ($short =~ /^(Please|Cho+se|Enter|Select|Specify|Give)/) {
+                    $self->pointed_hint('using-imperative-form-in-templates',
+                        $pointer, $name);
+                }
+            }
+            if ($ttype eq 'boolean') {
+                if ($short !~ /\?/) {
+                    $self->pointed_hint('malformed-question-in-templates',
+                        $pointer, $name);
+                }
+            }
+            if (defined $extended && $extended =~ /[^\?]\?(\s+|$)/) {
+                $self->pointed_hint(
+                    'using-question-in-extended-description-in-templates',
+                    $pointer, $name);
+            }
+            if ($ttype eq 'note') {
+                if ($short =~ /[.?;:]$/) {
+                    $self->pointed_hint('malformed-title-in-templates',
+                        $pointer, $name);
+                }
+            }
+            if (length $short > $MAXIMUM_TEMPLATE_SYNOPSIS) {
+                $self->pointed_hint('too-long-short-description-in-templates',
+                    $pointer, $name)
+                  unless $self->processable->type eq 'udeb'
+                  && $ttype eq 'text';
+            }
+            if (defined $description) {
+                if ($description
+                    =~ /(\A|\s)(I|[Mm]y|[Ww]e|[Oo]ur|[Oo]urs|mine|myself|ourself|me|us)(\Z|\s)/
+                ) {
+                    $self->pointed_hint('using-first-person-in-templates',
+                        $pointer,$name);
+                }
+                if (    $description =~ /[ \'\"]yes[ \'\",;.]/i
+                    and $ttype eq 'boolean') {
+
+                    $self->pointed_hint(
+                        'making-assumptions-about-interfaces-in-templates',
+                        $pointer, $name);
+                }
+            }
+
+            # Check whether the extended description is too long.
+            if ($extended) {
+
+                my $lines = 0;
+                for my $string (split(/\n/, $extended)) {
+
+                    while (length $string > $MAXIMUM_LINE_LENGTH) {
+
+                        my $index
+                          = rindex($string, $SPACE, $MAXIMUM_LINE_LENGTH);
+
+                        if ($index == $ITEM_NOT_FOUND) {
+                            $index = index($string, $SPACE);
+                        }
+
+                        if ($index == $ITEM_NOT_FOUND) {
+                            $string = $EMPTY;
+
+                        } else {
+                            $string = substr($string, $index + 1);
+                            $lines++;
+                        }
+                    }
+
+                    $lines++;
+                }
+
+                if ($lines > $MAXIMUM_LINES) {
+                    $self->pointed_hint(
+                        'too-long-extended-description-in-templates',
+                        $pointer, $name);
+                }
+            }
+        }
+    }
+
+    # Check the maintainer scripts.
+
+    my ($config_calls_db_input, $db_purge);
+    my (%templates_used, %template_aliases);
+    for my $file (qw(config prerm postrm preinst postinst)) {
+
+        my $potential_makedev = {};
+
+        my $item = $self->processable->control->lookup($file);
+
+        if (defined $item && $item->is_file && $item->is_open_ok) {
+
+            my ($usesconfmodule, $obsoleteconfmodule, $db_input, $isdefault);
+
+            open(my $fd, '<', $item->unpacked_path)
+              or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+            # Only check scripts.
+            my $fl = <$fd>;
+            unless ($fl && $fl =~ /^\#!/) {
+                close($fd);
+                next;
+            }
+
+            my $position = 1;
+            while (my $line = <$fd>) {
+
+                # not perfect for Perl, but should be OK
+                $line =~ s/#.*//;
+
+                next
+                  unless $line =~ /\S/;
+
+                while ($line =~ s{\\$}{}) {
+                    my $next = <$fd>;
+                    ++$position;
+
+                    last
+                      unless $next;
+
+                    $line .= $next;
+                }
+
+                if ($line =~ m{(?:\.|source)\s+/usr/share/debconf/confmodule}
+                    || $line=~ /(?:use|require)\s+Debconf::Client::ConfModule/)
+                {
+                    $usesconfmodule=1;
+                }
+
+                my $pointer = $item->pointer($position);
+
+                if (
+                    !$obsoleteconfmodule
+                    && $line =~ m{(/usr/share/debconf/confmodule\.sh|
+                   Debian::DebConf::Client::ConfModule)}x
+                ) {
+                    my $module = $1;
+
+                    $self->pointed_hint('loads-obsolete-confmodule', $pointer,
+                        $module);
+
+                    $usesconfmodule = 1;
+                    $obsoleteconfmodule = 1;
+                }
+
+                if ($item->name eq 'config' && $line =~ /db_input/) {
+                    $config_calls_db_input = 1;
+                }
+
+                if (   $item->name eq 'postinst'
+                    && !$db_input
+                    && $line =~ /db_input/
+                    && !$config_calls_db_input) {
+
+                    # TODO: Perl?
+                    $self->pointed_hint('postinst-uses-db-input', $pointer)
+                      unless $self->processable->type eq 'udeb';
+                    $db_input=1;
+                }
+
+                if ($line =~ m{/dev/}) {
+                    $potential_makedev->{$position} = 1;
+                }
+
+                if (
+                    $line =~m{\A \s*(?:db_input|db_text)\s+
+                     [\"\']? (\S+?) [\"\']? \s+ (\S+)\s}xsm
+                ) {
+                    my $priority = $1;
+                    my $unmangled = $2;
+
+                    $templates_used{$self->get_template_name($unmangled)}= 1;
+
+                    if ($priority !~ /^\$\S+$/) {
+
+                        $self->pointed_hint('unknown-debconf-priority',
+                            $pointer, $priority)
+                          unless ($valid_priorities{$priority});
+
+                        $self->pointed_hint('possible-debconf-note-abuse',
+                            $pointer, $unmangled)
+                          if (
+                            $potential_db_abuse{$unmangled}
+                            and (
+                                not($potential_makedev->{($position - 1)}
+                                    and ($priority eq 'low'))
+                            )
+                            and ($priority eq 'low' || $priority eq 'medium')
+                          );
+                    }
+                }
+
+                if (
+                    $line =~m{ \A \s* (?:db_get|db_set(?:title)?) \s+ 
+                       [\"\']? (\S+?) [\"\']? (?:\s|\Z)}xsm
+                ) {
+                    $templates_used{$self->get_template_name($1)} = 1;
+                }
+
+                # Try to handle Perl somewhat.
+                if ($line =~ /^\s*(?:.*=\s*get|set)\s*\(\s*[\"\'](\S+?)[\"\']/
+                    || $line
+                    =~ /\b(?:metaget|settitle)\s*\(\s*[\"\'](\S+?)[\"\']/) {
+                    $templates_used{$1} = 1;
+                }
+
+                if ($line=~ /^\s*db_register\s+[\"\']?(\S+?)[\"\']?\s+(\S+)\s/)
+                {
+                    my ($template, $question) = ($1, $2);
+                    push @{$template_aliases{$template}}, $question;
+                }
+                if (!$isdefault && $line =~ /db_fset.*isdefault/) {
+                    # TODO: Perl?
+                    $self->pointed_hint('isdefault-flag-is-deprecated',
+                        $pointer);
+                    $isdefault = 1;
+                }
+
+                if (!$db_purge && $line =~ /db_purge/) {    # TODO: Perl?
+                    $db_purge = 1;
+                }
+
+            } continue {
+                ++$position;
+            }
+
+            close $fd;
+
+            if ($self->processable->type ne 'udeb') {
+                if ($item->name eq 'config'
+                    || ($seenconfig && $item->name eq 'postinst')){
+
+                    $self->pointed_hint("$file-does-not-load-confmodule",
+                        $item->pointer)
+                      unless $usesconfmodule;
+                }
+            }
+
+            if ($item->name eq 'postrm') {
+                # If we haven't seen db_purge we emit the tag unless the
+                # package is a debconf provider (in which case db_purge
+                # won't be available)
+                unless ($db_purge or $selfrelation->satisfies($ANY_DEBCONF)) {
+
+                    $self->pointed_hint('postrm-does-not-purge-debconf',
+                        $item->pointer);
+                }
+            }
+
+        } elsif ($file eq 'postinst') {
+
+            $self->hint('postinst-does-not-load-confmodule', $file)
+              if $self->processable->type ne 'udeb' && $seenconfig;
+
+        } elsif ($file eq 'postrm') {
+            # Make an exception for debconf providing packages as some of
+            # them (incl. "debconf" itself) cleans up in prerm and have no
+            # postrm script at all.
+            $self->hint('postrm-does-not-purge-debconf', $file)
+              unless $self->processable->type eq 'udeb'
+              or $selfrelation->satisfies($ANY_DEBCONF);
+        }
+    }
+
+    for my $name (keys %template_by_name) {
+
+        $name =~ s/\s+\Z//;
+
+        my $used = 0;
+
+        if ($templates_used{$name}) {
+            $used = 1;
+        } else {
+            foreach my $alias (@{$template_aliases{$name}}) {
+                if ($templates_used{$alias}) {
+                    $used = 1;
+                    last;
+                }
+            }
+        }
+
+        my $template = $template_by_name{$name};
+        my $position = $template->position('Template');
+        my $pointer = $ctrl_templates->pointer($position);
+
+        $self->pointed_hint('unused-debconf-template', $pointer, $name)
+          unless $name =~ m{^shared/packages-(wordlist|ispell)$}
+          || $name =~ m{/languages$}
+          || $used
+          || $self->processable->name eq 'debconf'
+          || $self->processable->type eq 'udeb';
+    }
+
+    # Check that the right dependencies are in the control file.  Accept any
+    # package that might provide debconf functionality.
+
+    if ($usespreinst) {
+        unless ($self->processable->relation('Pre-Depends')
+            ->satisfies($ANY_DEBCONF)){
+            $self->hint('missing-debconf-dependency-for-preinst')
+              unless $self->processable->type eq 'udeb';
+        }
+    } else {
+        unless ($alldependencies->satisfies($ANY_DEBCONF) or $usesdbconfig) {
+            $self->hint('missing-debconf-dependency');
+        }
+    }
+
+    # Now make sure that no scripts are using debconf as a registry.
+    # Unfortunately this requires us to unpack to level 2 and grep all the
+    # scripts in the package.
+    # the following checks is ignored if the package being checked is debconf
+    # itself.
+
+    return
+      if ($self->processable->name eq 'debconf')
+      || ($self->processable->type eq 'udeb');
+
+    my @scripts
+      = grep { $_->is_script } @{$self->processable->installed->sorted_list};
+    for my $item (@scripts) {
+
+        next
+          unless $item->is_open_ok;
+
+        open(my $fd, '<', $item->unpacked_path)
+          or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+        my $position = 1;
+        while (my $line = <$fd>) {
+
+            # Not perfect for Perl, but should be OK
+            $line =~ s/#.*//;
+
+            if (   $line =~ m{/usr/share/debconf/confmodule}
+                || $line =~ /(?:Debconf|Debian::DebConf)::Client::ConfModule/){
+
+                $self->pointed_hint('debconf-is-not-a-registry',
+                    $item->pointer($position));
+                last;
+            }
+
+        } continue {
+            ++$position;
+        }
+
+        close $fd;
+    }
+
+    return;
+} # </run>
+
+# -----------------------------------
+
+# Count the number of choices.  Splitting code copied from debconf 1.5.8
+# (Debconf::Question).
+sub count_choices {
+    my ($choices) = @_;
+    my @items;
+    my $item = $EMPTY;
+    for my $chunk (split /(\\[, ]|,\s+)/, $choices) {
+        if ($chunk =~ /^\\([, ])$/) {
+            $item .= $1;
+        } elsif ($chunk =~ /^,\s+$/) {
+            push(@items, $item);
+            $item = $EMPTY;
+        } else {
+            $item .= $chunk;
+        }
+    }
+    push(@items, $item) if $item ne $EMPTY;
+    return scalar(@items);
+}
+
+# Manually interpolate shell variables, eg. $DPKG_MAINTSCRIPT_PACKAGE
+sub get_template_name {
+    my ($self, $name) = @_;
+
+    my $package = $self->processable->name;
+    return $name =~ s/^\$DPKG_MAINTSCRIPT_PACKAGE/$package/r;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/DesktopEntries.pm b/lib/Lintian/Check/Debian/DesktopEntries.pm
new file mode 100644
index 0000000..cff6042
--- /dev/null
+++ b/lib/Lintian/Check/Debian/DesktopEntries.pm
@@ -0,0 +1,58 @@
+# debian/desktop-entries -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::DesktopEntries;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    return
+      if $self->processable->native;
+
+    my $debiandir = $self->processable->patched->resolve_path('debian');
+    return
+      unless $debiandir;
+
+    my @files = grep { $_->is_file } $debiandir->descendants;
+    my @nopatches = grep { $_->name !~ m{^debian/patches/} } @files;
+
+    my @manpages = grep { $_->basename =~ m{\.desktop$} } @nopatches;
+
+    $self->pointed_hint('maintainer-desktop-entry', $_->pointer) for @manpages;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Filenames.pm b/lib/Lintian/Check/Debian/Filenames.pm
new file mode 100644
index 0000000..c18b129
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Filenames.pm
@@ -0,0 +1,78 @@
+# debian/filenames -- lintian check script -*- perl -*-
+
+# Copyright (C) 2019 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Filenames;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    # names are different in installation packages (see #429510)
+    # README and TODO may be handled differently
+
+    my @often_misnamed = (
+        { correct => 'NEWS', problematic => 'NEWS.Debian' },
+        { correct => 'NEWS', problematic => 'NEWS.debian' },
+        { correct => 'TODO', problematic => 'TODO.Debian' },
+        { correct => 'TODO', problematic => 'TODO.debian' }
+    );
+
+    for my $relative (@often_misnamed) {
+
+        my $problematic_item = $self->processable->patched->resolve_path(
+            'debian/' . $relative->{problematic});
+
+        next
+          unless defined $problematic_item;
+
+        my $correct_name = 'debian/' . $relative->{correct};
+        if ($self->processable->patched->resolve_path($correct_name)) {
+
+            $self->pointed_hint('duplicate-packaging-file',
+                $problematic_item->pointer,
+                'better:', $correct_name);
+
+        } else {
+            $self->pointed_hint(
+                'incorrect-packaging-filename',
+                $problematic_item->pointer,
+                'better:', $correct_name
+            );
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Files.pm b/lib/Lintian/Check/Debian/Files.pm
new file mode 100644
index 0000000..921f48b
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Files.pm
@@ -0,0 +1,60 @@
+# debian/files -- lintian check script -*- perl -*-
+#
+# based on debhelper check,
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Files;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->name eq 'debian/files';
+
+    $self->pointed_hint('debian-files-list-in-source', $item->pointer)
+      if $item->size > 0;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/LineSeparators.pm b/lib/Lintian/Check/Debian/LineSeparators.pm
new file mode 100644
index 0000000..3c174ab
--- /dev/null
+++ b/lib/Lintian/Check/Debian/LineSeparators.pm
@@ -0,0 +1,62 @@
+# debian/line-separators -- lintian check script -*- perl -*-
+#
+# based on debhelper check,
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::LineSeparators;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(none);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# files in ./debian to check for line terminators
+my @CANDIDATES = qw(debian/control debian/changelog);
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      if none { $item->name eq $_ } @CANDIDATES;
+
+    $self->pointed_hint('carriage-return-line-feed', $item->pointer)
+      if $item->bytes =~ m{\r\n\Z}m;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/LintianOverrides.pm b/lib/Lintian/Check/Debian/LintianOverrides.pm
new file mode 100644
index 0000000..448e7f9
--- /dev/null
+++ b/lib/Lintian/Check/Debian/LintianOverrides.pm
@@ -0,0 +1,64 @@
+# debian/lintian-overrides -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::LintianOverrides;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    my $ppkg = quotemeta($self->processable->name);
+
+    # misplaced overrides
+    if ($item->name =~ m{^usr/share/doc/$ppkg/override\.[lL]intian(?:\.gz)?$}
+        || $item->name =~ m{^usr/share/lintian/overrides/$ppkg/.+}) {
+
+        $self->pointed_hint('override-file-in-wrong-location', $item->pointer);
+
+    } elsif ($item->name =~ m{^usr/share/lintian/overrides/(.+)/.+$}) {
+
+        my $expected = $1;
+
+        $self->pointed_hint('override-file-in-wrong-package',
+            $item->pointer, $expected)
+          unless $self->processable->name eq $expected;
+    }
+
+    $self->pointed_hint('old-source-override-location', $item->pointer)
+      if $item->name eq 'debian/source.lintian-overrides';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/LintianOverrides/Comments.pm b/lib/Lintian/Check/Debian/LintianOverrides/Comments.pm
new file mode 100644
index 0000000..11c0077
--- /dev/null
+++ b/lib/Lintian/Check/Debian/LintianOverrides/Comments.pm
@@ -0,0 +1,88 @@
+# debian/lintian-overrides/comments -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::LintianOverrides::Comments;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use POSIX qw(ENOENT);
+
+use Lintian::Spelling qw(check_spelling check_spelling_picky);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub always {
+    my ($self) = @_;
+
+    my @declared_overrides = @{$self->processable->overrides};
+
+    for my $override (@declared_overrides) {
+
+        next
+          unless length $override->justification;
+
+        my $tag_name = $override->tag_name;
+
+        # comments appear one or more lines before the override
+        # but they were concatenated
+        my $position = $override->position - 1;
+
+        my $pointer= $self->processable->override_file->pointer($position);
+
+        check_spelling(
+            $self->data,
+            $override->justification,
+            $self->group->spelling_exceptions,
+            $self->emitter('spelling-in-override-comment',$pointer, $tag_name)
+        );
+
+        check_spelling_picky(
+            $self->data,
+            $override->justification,
+            $self->emitter(
+                'capitalization-in-override-comment',
+                $pointer,$tag_name
+            )
+        );
+    }
+
+    return;
+}
+
+sub emitter {
+    my ($self, @prefixed) = @_;
+
+    return sub {
+        return $self->pointed_hint(@prefixed, @_);
+    };
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/LintianOverrides/Duplicate.pm b/lib/Lintian/Check/Debian/LintianOverrides/Duplicate.pm
new file mode 100644
index 0000000..e52d140
--- /dev/null
+++ b/lib/Lintian/Check/Debian/LintianOverrides/Duplicate.pm
@@ -0,0 +1,75 @@
+# debian/lintian-overrides/duplicate -- lintian check script -*- perl -*-
+
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::LintianOverrides::Duplicate;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $SPACE => q{ };
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub always {
+    my ($self) = @_;
+
+    my %pattern_tracker;
+    for my $override (@{$self->processable->overrides}) {
+
+        my $pattern = $override->pattern;
+
+        # catch renames
+        my $tag_name = $self->profile->get_current_name($override->tag_name);
+
+        push(@{$pattern_tracker{$tag_name}{$pattern}}, $override);
+    }
+
+    for my $tag_name (keys %pattern_tracker) {
+        for my $pattern (keys %{$pattern_tracker{$tag_name}}) {
+
+            my @overrides = @{$pattern_tracker{$tag_name}{$pattern}};
+
+            my @same_context = map { $_->position } @overrides;
+            my $line_numbers = join($SPACE, (sort @same_context));
+
+            my $override_item = $self->processable->override_file;
+
+            $self->pointed_hint('duplicate-override-context',
+                $override_item->pointer,$tag_name,"(lines $line_numbers)")
+              if @overrides > 1;
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/LintianOverrides/Malformed.pm b/lib/Lintian/Check/Debian/LintianOverrides/Malformed.pm
new file mode 100644
index 0000000..3772889
--- /dev/null
+++ b/lib/Lintian/Check/Debian/LintianOverrides/Malformed.pm
@@ -0,0 +1,52 @@
+# debian/lintian-overrides/malformed -- lintian check script -*- perl -*-
+
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::LintianOverrides::Malformed;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub always {
+    my ($self) = @_;
+
+    for my $error (@{$self->processable->override_errors}) {
+
+        my $message = $error->{message};
+        my $pointer = $error->{pointer};
+
+        $self->pointed_hint('malformed-override', $pointer, $message);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/LintianOverrides/Mystery.pm b/lib/Lintian/Check/Debian/LintianOverrides/Mystery.pm
new file mode 100644
index 0000000..92e6125
--- /dev/null
+++ b/lib/Lintian/Check/Debian/LintianOverrides/Mystery.pm
@@ -0,0 +1,65 @@
+# debian/lintian-overrides/mystery -- lintian check script -*- perl -*-
+
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::LintianOverrides::Mystery;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $ARROW => q{=>};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub always {
+    my ($self) = @_;
+
+    for my $override (@{$self->processable->overrides}) {
+
+        my $override_item = $self->processable->override_file;
+        my $pointer = $override_item->pointer($override->position);
+
+        my $mystery_name = $override->tag_name;
+        my $current_name = $self->profile->get_current_name($mystery_name);
+
+        $self->pointed_hint('alien-tag', $pointer, $mystery_name)
+          if !length $current_name;
+
+        $self->pointed_hint('renamed-tag', $pointer, $mystery_name, $ARROW,
+            $current_name)
+          if length $current_name
+          && $current_name ne $mystery_name;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/LintianOverrides/Restricted.pm b/lib/Lintian/Check/Debian/LintianOverrides/Restricted.pm
new file mode 100644
index 0000000..cc2cda4
--- /dev/null
+++ b/lib/Lintian/Check/Debian/LintianOverrides/Restricted.pm
@@ -0,0 +1,80 @@
+# debian/lintian-overrides/restricted -- lintian check script -*- perl -*-
+
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::LintianOverrides::Restricted;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(true);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub always {
+    my ($self) = @_;
+
+    for my $override (@{$self->processable->overrides}) {
+
+        my $override_item = $self->processable->override_file;
+        my $pointer = $override_item->pointer($override->position);
+
+        my @architectures = @{$override->architectures};
+
+        if (@architectures && $self->processable->architecture eq 'all') {
+            $self->pointed_hint('invalid-override-restriction',
+                $pointer,'Architecture list in Arch:all installable');
+            next;
+        }
+
+        my @invalid
+          = grep { !$self->data->architectures->valid_restriction($_) }
+          @architectures;
+        $self->pointed_hint('invalid-override-restriction',
+            $pointer,"Unknown architecture wildcard $_")
+          for @invalid;
+
+        next
+          if @invalid;
+
+        # count negations
+        my $negations = true { /^!/ } @architectures;
+
+        # confirm it is either all or none
+        if ($negations > 0 && $negations != @architectures) {
+            $self->pointed_hint('invalid-override-restriction',
+                $pointer,'Inconsistent architecture negation');
+            next;
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Maintscript.pm b/lib/Lintian/Check/Debian/Maintscript.pm
new file mode 100644
index 0000000..adee6be
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Maintscript.pm
@@ -0,0 +1,73 @@
+# debian/maintscript -- lintian check script -*- perl -*-
+
+# Copyright (C) 1999 by Joey Hess
+# Copyright (C) 2016-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Maintscript;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->dirname eq 'debian/';
+
+    return
+      unless $item->basename =~ m{ (?: ^ | [.] ) maintscript $}x;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        my $pointer = $item->pointer($position);
+
+        $self->pointed_hint('maintscript-includes-maint-script-parameters',
+            $pointer)
+          if $line =~ /--\s+"\$(?:@|{@})"\s*$/;
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/ManualPages.pm b/lib/Lintian/Check/Debian/ManualPages.pm
new file mode 100644
index 0000000..f1b654a
--- /dev/null
+++ b/lib/Lintian/Check/Debian/ManualPages.pm
@@ -0,0 +1,67 @@
+# debian/manual-pages -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::ManualPages;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw{none};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    return
+      if $self->processable->native;
+
+    my $debiandir = $self->processable->patched->resolve_path('debian');
+    return
+      unless $debiandir;
+
+    my @files = grep { $_->is_file } $debiandir->descendants;
+    my @nopatches = grep { $_->name !~ m{^debian/patches/} } @files;
+
+    my @manual_pages = grep { $_->basename =~ m{\.\d$} } @nopatches;
+
+    for my $item (@manual_pages) {
+
+        my $command = $item->basename;
+        $command =~ s/ [.] \d $//x;
+
+        $self->pointed_hint('maintainer-manual-page', $item->pointer)
+          if none { $command eq $_->basename } @files;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/NotInstalled.pm b/lib/Lintian/Check/Debian/NotInstalled.pm
new file mode 100644
index 0000000..6e787b4
--- /dev/null
+++ b/lib/Lintian/Check/Debian/NotInstalled.pm
@@ -0,0 +1,74 @@
+# debian/not-installed -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::NotInstalled;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->name eq 'debian/not-installed';
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        # disregard comments
+        next
+          if $line =~ m{^ \s* [#] }x;
+
+        # architecture triplet
+        $self->pointed_hint('unwanted-path-too-specific',
+            $item->pointer($position), $line)
+          if $line =~ m{^ usr/lib/ [^/-]+ - [^/-]+ - [^/-]+ / }x
+          && $line !~ m{^ usr/lib/ [*] / }x;
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Patches.pm b/lib/Lintian/Check/Debian/Patches.pm
new file mode 100644
index 0000000..b9a3ec2
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Patches.pm
@@ -0,0 +1,104 @@
+# debian/patches -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2007 Marc Brockschmidt
+# Copyright (C) 2008 Raphael Hertzog
+# Copyright (C) 2018-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Patches;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Path::Tiny;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my @patch_system;
+
+    # Get build deps so we can decide which build system the
+    # maintainer meant to use:
+    my $build_deps = $self->processable->relation('Build-Depends-All');
+
+    # Get source package format
+    my $source_format = $self->processable->fields->value('Format');
+    my $quilt_format = ($source_format =~ /3\.\d+ \(quilt\)/) ? 1 : 0;
+
+    my $debian_dir = $self->processable->patched->resolve_path('debian/');
+    return
+      unless defined $debian_dir;
+
+    my $patch_dir = $debian_dir->resolve_path('patches');
+
+    # Find debian/patches/series, assuming debian/patches is a (symlink to a)
+    # dir.  There are cases, where it is a file (ctwm: #778556)
+    my $patch_series;
+    $patch_series
+      = $self->processable->patched->resolve_path('debian/patches/series');
+
+    push(@patch_system, 'dpatch')
+      if $build_deps->satisfies('dpatch');
+
+    push(@patch_system, 'quilt')
+      if $quilt_format || $build_deps->satisfies('quilt');
+
+    $self->hint('patch-system', $_) for @patch_system;
+
+    $self->hint('more-than-one-patch-system')
+      if @patch_system > 1;
+
+    if (@patch_system && !$quilt_format) {
+
+        my $readme = $debian_dir->resolve_path('README.source');
+        $self->hint('patch-system-but-no-source-readme')
+          unless defined $readme;
+    }
+
+    my @direct_changes
+      = grep { !m{^debian/} } keys %{$self->processable->diffstat};
+    if (@direct_changes) {
+
+        my $files = $direct_changes[0];
+        $files .= " and $#direct_changes more"
+          if @direct_changes > 1;
+
+        $self->hint('patch-system-but-direct-changes-in-diff', $files)
+          if @patch_system;
+
+        $self->hint('direct-changes-in-diff-but-no-patch-system', $files)
+          unless @patch_system;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Patches/Count.pm b/lib/Lintian/Check/Debian/Patches/Count.pm
new file mode 100644
index 0000000..589e2ba
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Patches/Count.pm
@@ -0,0 +1,54 @@
+# debian/patches/count -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Patches::Count;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->name eq 'debian/patches/series';
+
+    my @lines = split(/\n/, $item->decoded_utf8);
+
+    # remove lines containing only comments
+    my @patches = grep { !/^\s*(?:#|$)/ } @lines;
+
+    $self->pointed_hint('number-of-patches', $item->pointer, scalar @patches);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Patches/Dep3.pm b/lib/Lintian/Check/Debian/Patches/Dep3.pm
new file mode 100644
index 0000000..6624a0c
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Patches/Dep3.pm
@@ -0,0 +1,105 @@
+# debian/patches/dep3 -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Patches::Dep3;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any none);
+use Syntax::Keyword::Try;
+use Unicode::UTF8 qw(valid_utf8 decode_utf8);
+
+use Lintian::Deb822;
+
+const my $EMPTY => q{};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->name =~ m{^debian/patches/};
+
+    return
+      unless $item->is_file;
+
+    return
+      if $item->name eq 'debian/patches/series'
+      || $item->name eq 'debian/patches/README';
+
+    my $bytes = $item->bytes;
+    return
+      unless length $bytes;
+
+    my ($headerbytes) = split(/^---/m, $bytes, 2);
+
+    return
+      unless valid_utf8($headerbytes);
+
+    my $header = decode_utf8($headerbytes);
+    return
+      unless length $header;
+
+    my $deb822 = Lintian::Deb822->new;
+
+    my @sections;
+    try {
+        @sections = $deb822->parse_string($header);
+
+    } catch {
+        return;
+    }
+
+    return
+      unless @sections;
+
+    # use last mention when present multiple times
+    my $origin = $deb822->last_mention('Origin');
+
+    my ($category) = split(m{\s*,\s*}, $origin, 2);
+    $category //= $EMPTY;
+    return
+      if any { $category eq $_ } qw(upstream backport);
+
+    $self->pointed_hint('patch-not-forwarded-upstream', $item->pointer)
+      if $deb822->last_mention('Forwarded') eq 'no'
+      || none { length } (
+        $deb822->last_mention('Applied-Upstream'),
+        $deb822->last_mention('Bug'),
+        $deb822->last_mention('Forwarded')
+      );
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Patches/Dpatch.pm b/lib/Lintian/Check/Debian/Patches/Dpatch.pm
new file mode 100644
index 0000000..337fa53
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Patches/Dpatch.pm
@@ -0,0 +1,150 @@
+# debian/patches -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2007 Marc Brockschmidt
+# Copyright (C) 2008 Raphael Hertzog
+# Copyright (C) 2018-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Patches::Dpatch;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+
+sub source {
+    my ($self) = @_;
+
+    my $build_deps = $self->processable->relation('Build-Depends-All');
+    return
+      unless $build_deps->satisfies('dpatch');
+
+    my $patch_dir
+      = $self->processable->patched->resolve_path('debian/patches/');
+    return
+      unless defined $patch_dir;
+
+    $self->hint('package-uses-deprecated-dpatch-patch-system');
+
+    my @list_files
+      = grep {$_->basename =~ m/^00list/ && $_->is_open_ok}
+      $patch_dir->children;
+
+    $self->hint('dpatch-build-dep-but-no-patch-list')
+      unless @list_files;
+
+    my $options_file = $patch_dir->resolve_path('00options');
+
+    my $list_uses_cpp = 0;
+    $list_uses_cpp = 1
+      if defined $options_file
+      && $options_file->decoded_utf8 =~ /DPATCH_OPTION_CPP=1/;
+
+    for my $file (@list_files) {
+        my @patches;
+
+        open(my $fd, '<', $file->unpacked_path)
+          or die encode_utf8('Cannot open ' . $file->unpacked_path);
+
+        while(my $line = <$fd>) {
+            chomp $line;
+
+            #ignore comments or CPP directive
+            next
+              if $line =~ /^\#/;
+
+            # remove C++ style comments
+            $line =~ s{//.*}{}
+              if $list_uses_cpp;
+
+            if ($list_uses_cpp && $line =~ m{/\*}) {
+
+                # remove C style comments
+                $line .= <$fd> while ($line !~ m{\*/});
+
+                $line =~ s{/\*[^*]*\*/}{}g;
+            }
+
+            #ignore blank lines
+            next
+              if $line =~ /^\s*$/;
+
+            push @patches, split($SPACE, $line);
+        }
+        close($fd);
+
+        for my $patch_name (@patches) {
+
+            my $patch_file = $patch_dir->child($patch_name);
+            $patch_file = $patch_dir->child("${patch_name}.dpatch")
+              unless defined $patch_file;
+
+            unless (defined $patch_file) {
+                $self->hint('dpatch-index-references-non-existent-patch',
+                    $patch_name);
+                next;
+            }
+
+            next
+              unless $patch_file->is_open_ok;
+
+            my $description = $EMPTY;
+            open(my $fd, '<', $patch_file->unpacked_path)
+              or die encode_utf8('Cannot open ' . $patch_file->unpacked_path);
+
+            while (my $line = <$fd>) {
+                # stop if something looking like a patch
+                # starts:
+                last
+                  if $line =~ /^---/;
+                # note comment if we find a proper one
+                $description .= $1
+                  if $line =~ /^\#+\s*DP:\s*(\S.*)$/
+                  && $1 !~ /^no description\.?$/i;
+                $description .= $1
+                  if $line =~ /^\# (?:Description|Subject): (.*)/;
+            }
+            close($fd);
+
+            $self->pointed_hint('dpatch-missing-description',
+                $patch_file->pointer)
+              unless length $description;
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Patches/Quilt.pm b/lib/Lintian/Check/Debian/Patches/Quilt.pm
new file mode 100644
index 0000000..2e78055
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Patches/Quilt.pm
@@ -0,0 +1,290 @@
+# debian/patches/quilt -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2007 Marc Brockschmidt
+# Copyright (C) 2008 Raphael Hertzog
+# Copyright (C) 2018-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Patches::Quilt;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any);
+use Unicode::UTF8 qw(decode_utf8 encode_utf8);
+
+use Lintian::IPC::Run3 qw(safe_qx);
+use Lintian::Spelling qw(check_spelling);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $PATCH_DESC_TEMPLATE =>
+  'TODO: Put a short summary on the line above and replace this paragraph';
+const my $EMPTY => q{};
+
+sub spelling_tag_emitter {
+    my ($self, $tag_name, $item, @orig_args) = @_;
+
+    my $pointer = $item->pointer($.);
+
+    return sub {
+        return $self->pointed_hint($tag_name, $pointer, @orig_args, @_);
+    };
+}
+
+sub source {
+    my ($self) = @_;
+
+    my $build_deps = $self->processable->relation('Build-Depends-All');
+
+    my $source_format = $self->processable->fields->value('Format');
+    my $quilt_format = ($source_format =~ /3\.\d+ \(quilt\)/) ? 1 : 0;
+
+    my $debian_dir = $self->processable->patched->resolve_path('debian/');
+    return
+      unless defined $debian_dir;
+
+    my $patch_dir = $debian_dir->resolve_path('patches');
+    my %known_files;
+
+    # Find debian/patches/series, assuming debian/patches is a (symlink to a)
+    # dir.  There are cases, where it is a file (ctwm: #778556)
+    my $patch_series;
+    $patch_series
+      = $self->processable->patched->resolve_path('debian/patches/series');
+
+    # 3.0 (quilt) sources do not need quilt
+    unless ($quilt_format) {
+
+        $self->hint('quilt-build-dep-but-no-series-file')
+          if $build_deps->satisfies('quilt')
+          && (!defined $patch_series || !$patch_series->is_open_ok);
+
+        $self->pointed_hint('quilt-series-but-no-build-dep',
+            $patch_series->pointer)
+          if $patch_series
+          && $patch_series->is_file
+          && !$build_deps->satisfies('quilt');
+    }
+
+    return
+      unless $quilt_format || $build_deps->satisfies('quilt');
+
+    if ($patch_series && $patch_series->is_open_ok) {
+
+        my @patch_names;
+
+        open(my $series_fd, '<', $patch_series->unpacked_path)
+          or die encode_utf8('Cannot open ' . $patch_series->unpacked_path);
+
+        my $position = 1;
+        while (my $line = <$series_fd>) {
+
+            # Strip comment
+            $line =~ s/(?:^|\s+)#.*$//;
+
+            if (rindex($line,"\n") < 0) {
+                $self->pointed_hint('quilt-series-without-trailing-newline',
+                    $patch_series->pointer);
+            }
+
+            # trim both ends
+            $line =~ s/^\s+|\s+$//g;
+
+            next
+              unless length $line;
+
+            if ($line =~ m{^(\S+)\s+(\S.*)$}) {
+
+                my $patch = $1;
+                my $patch_options = $2;
+
+                push(@patch_names, $patch);
+
+                $self->pointed_hint('quilt-patch-with-non-standard-options',
+                    $patch_series->pointer($position), $line)
+                  unless $patch_options eq '-p1';
+
+            } else {
+                push(@patch_names, $line);
+            }
+
+        } continue {
+            ++$position;
+        }
+
+        close $series_fd;
+
+        my @patch_files;
+        for my $name (@patch_names) {
+
+            my $item = $patch_dir->resolve_path($name);
+
+            if (defined $item && $item->is_file) {
+                push(@patch_files, $item);
+
+            } else {
+                $self->pointed_hint(
+                    'quilt-series-references-non-existent-patch',
+                    $patch_series->pointer, $name);
+            }
+        }
+
+        for my $item (@patch_files) {
+
+            next
+              unless $item->is_open_ok;
+
+            my $description = $EMPTY;
+            my $has_template_description = 0;
+
+            open(my $patch_fd, '<', $item->unpacked_path)
+              or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+            while (my $line = <$patch_fd>) {
+
+                # stop if something looking like a patch starts:
+                last
+                  if $line =~ /^---/;
+
+                next
+                  if $line =~ /^\s*$/;
+
+                # Skip common "lead-in" lines
+                $description .= $line
+                  unless $line =~ m{^(?:Index: |=+$|diff .+|index |From: )};
+
+                $has_template_description = 1
+                  if $line =~ / \Q$PATCH_DESC_TEMPLATE\E /msx;
+            }
+            close $patch_fd;
+
+            $self->pointed_hint('quilt-patch-missing-description',
+                $item->pointer)
+              unless length $description;
+
+            $self->pointed_hint('quilt-patch-using-template-description',
+                $item->pointer)
+              if $has_template_description;
+
+            $self->check_patch($item, $description);
+        }
+    }
+
+    if ($quilt_format) { # 3.0 (quilt) specific checks
+         # Format 3.0 packages may generate a debian-changes-$version patch
+        my $version = $self->processable->fields->value('Version');
+        my $patch_header= $debian_dir->resolve_path('source/patch-header');
+        my $versioned_patch;
+
+        $versioned_patch= $patch_dir->resolve_path("debian-changes-$version")
+          if $patch_dir;
+
+        if (defined $versioned_patch && $versioned_patch->is_file) {
+
+            $self->pointed_hint('format-3.0-but-debian-changes-patch',
+                $versioned_patch->pointer)
+              if !defined $patch_header || !$patch_header->is_file;
+        }
+    }
+
+    if ($patch_dir and $patch_dir->is_dir and $source_format ne '2.0') {
+        # Check all series files, including $vendor.series
+        for my $item ($patch_dir->children) {
+            next
+              unless $item->name =~ /\/(.+\.)?series$/;
+            next
+              unless $item->is_open_ok;
+
+            $known_files{$item->basename}++;
+
+            open(my $fd, '<', $item->unpacked_path)
+              or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+            while (my $line = <$fd>) {
+                $known_files{$1}++
+                  if $line =~ m{^\s*(?:#+\s*)?(\S+)};
+            }
+            close($fd);
+
+            $self->pointed_hint('package-uses-vendor-specific-patch-series',
+                $item->pointer)
+              if $item->name =~ m{ [.]series $}x;
+        }
+
+        for my $item ($patch_dir->descendants) {
+            next
+              if $item->basename =~ /^README(\.patches)?$/
+              || $item->basename =~ /\.in/g;
+
+            # Use path relative to debian/patches for "subdir/foo"
+            my $name = substr($item, length $patch_dir);
+
+            $self->pointed_hint(
+                'patch-file-present-but-not-mentioned-in-series',
+                $item->pointer)
+              unless $known_files{$name} || $item->is_dir;
+        }
+    }
+
+    return;
+}
+
+# Checks on patches common to all build systems.
+sub check_patch {
+    my ($self, $item, $description) = @_;
+
+    unless (any { /(spelling|typo)/i } ($item->name, $description)) {
+        my $tag_emitter
+          = $self->spelling_tag_emitter('spelling-error-in-patch-description',
+            $item);
+        check_spelling($self->data, $description,
+            $self->group->spelling_exceptions,
+            $tag_emitter, 0);
+    }
+
+    # Use --strip=1 to strip off the first layer of directory in case
+    # the parent directory in which the patches were generated was
+    # named "debian".  This will produce false negatives for --strip=0
+    # patches that modify files in the debian/* directory, but as of
+    # 2010-01-01, all cases where the first level of the patch path is
+    # "debian/" in the archive are false positives.
+    my $bytes = safe_qx('lsdiff', '--strip=1', $item->unpacked_path);
+    my $output = decode_utf8($bytes);
+
+    my @debian_files = ($output =~ m{^((?:\./)?debian/.*)$}ms);
+
+    $self->pointed_hint('patch-modifying-debian-files', $item->pointer, $_)
+      for @debian_files;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/PoDebconf.pm b/lib/Lintian/Check/Debian/PoDebconf.pm
new file mode 100644
index 0000000..333fee5
--- /dev/null
+++ b/lib/Lintian/Check/Debian/PoDebconf.pm
@@ -0,0 +1,391 @@
+# debian/po-debconf -- lintian check script -*- perl -*-
+
+# Copyright (C) 2002-2004 by Denis Barbier <barbier@linuxfr.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::PoDebconf;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Cwd qw(realpath);
+use File::Temp();
+use IPC::Run3;
+use Syntax::Keyword::Try;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+sub source {
+    my ($self) = @_;
+
+    my $processable = $self->processable;
+
+    my $has_template = 0;
+    my @lang_templates;
+    my $full_translation = 0;
+
+    my $debian_dir = $processable->patched->resolve_path('debian/');
+    return
+      unless $debian_dir;
+
+    my $debian_po_dir = $debian_dir->resolve_path('po');
+    my ($templ_pot_path, $potfiles_in_path);
+
+    if ($debian_po_dir and $debian_po_dir->is_dir) {
+        $templ_pot_path = $debian_po_dir->resolve_path('templates.pot');
+        $potfiles_in_path = $debian_po_dir->resolve_path('POTFILES.in');
+    }
+
+    # First, check whether this package seems to use debconf but not
+    # po-debconf.  Read the templates file and look at the template
+    # names it provides, since some shared templates aren't
+    # translated.
+    for my $item ($debian_dir->children) {
+        next
+          unless $item->is_open_ok;
+
+        if ($item->basename =~ m/^(.+\.)?templates(\..+)?$/) {
+            if ($item->basename =~ m/templates\.\w\w(_\w\w)?$/) {
+                push(@lang_templates, $item);
+
+                open(my $fd, '<', $item->unpacked_path)
+                  or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+                while (my $line = <$fd>) {
+
+                    $self->pointed_hint('untranslatable-debconf-templates',
+                        $item->pointer($.))
+                      if $line =~ /^Description: (.+)/i
+                      && $1 !~/for internal use/;
+                }
+
+                close $fd;
+
+            } else {
+                open(my $fd, '<', $item->unpacked_path)
+                  or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+                my $in_template = 0;
+                my $saw_tl_note = 0;
+                while (my $line = <$fd>) {
+                    chomp $line;
+
+                    $self->pointed_hint('translated-default-field',
+                        $item->pointer($.))
+                      if $line =~ m{^_Default(?:Choice)?: [^\[]*$}
+                      && !$saw_tl_note;
+
+                    $self->pointed_hint('untranslatable-debconf-templates',
+                        $item->pointer($.))
+                      if $line =~ /^Description: (.+)/i
+                      && $1 !~/for internal use/;
+
+                    if ($line =~ /^#/) {
+                        # Is this a comment for the translators?
+                        $saw_tl_note = 1
+                          if $line =~ /translators/i;
+
+                        next;
+                    }
+
+                    # If it is not a continuous comment immediately before the
+                    # _Default(Choice) field, we don't care about it.
+                    $saw_tl_note = 0;
+
+                    if ($line =~ /^Template: (\S+)/i) {
+                        my $template = $1;
+                        next
+                          if $template eq 'shared/packages-wordlist'
+                          or $template eq 'shared/packages-ispell';
+
+                        next
+                          if $template =~ m{/languages$};
+
+                        $in_template = 1;
+
+                    } elsif ($in_template && $line =~ /^_?Description: (.+)/i){
+                        my $description = $1;
+                        next
+                          if $description =~ /for internal use/;
+                        $has_template = 1;
+
+                    } elsif ($in_template && !length($line)) {
+                        $in_template = 0;
+                    }
+                }
+
+                close($fd);
+            }
+        }
+    }
+
+    #TODO: check whether all templates are named in TEMPLATES.pot
+    if ($has_template) {
+        if (not $debian_po_dir or not $debian_po_dir->is_dir) {
+            $self->hint('not-using-po-debconf');
+            return;
+        }
+    } else {
+        return;
+    }
+
+    # If we got here, we're using po-debconf, so there shouldn't be any stray
+    # language templates left over from debconf-mergetemplate.
+    for my $item (@lang_templates) {
+        $self->pointed_hint('stray-translated-debconf-templates',
+            $item->pointer)
+          unless $item->basename =~ m{ templates[.]in$}x;
+    }
+
+    my $missing_files = 0;
+
+    if ($potfiles_in_path and $potfiles_in_path->is_open_ok) {
+
+        open(my $fd, '<', $potfiles_in_path->unpacked_path)
+          or
+          die encode_utf8('Cannot open ' . $potfiles_in_path->unpacked_path);
+
+        my $position = 1;
+        while (my $line = <$fd>) {
+            chomp $line;
+
+            next
+              if $line =~ /^\s*\#/;
+
+            $line =~ s/.*\]\s*//;
+
+            # Cannot check files which are not under debian/
+            # m,^\.\./, or
+            next
+              if $line eq $EMPTY;
+
+            my $pointer = $potfiles_in_path->pointer($position);
+
+            my $po_path = $debian_dir->resolve_path($line);
+            unless ($po_path and $po_path->is_file) {
+
+                $self->pointed_hint('missing-file-from-potfiles-in',
+                    $pointer, $line);
+                $missing_files = 1;
+            }
+
+        } continue {
+            ++$position;
+        }
+
+        close $fd;
+
+    } else {
+        $self->hint('missing-potfiles-in');
+        $missing_files = 1;
+    }
+    if (not $templ_pot_path or not $templ_pot_path->is_open_ok) {
+        # We use is_open_ok here, because if it is present, we will
+        # (have a subprocess) open it if the POTFILES.in file also
+        # existed.
+        $self->hint('missing-templates-pot');
+        $missing_files = 1;
+    }
+
+    if ($missing_files == 0) {
+        my $temp_obj
+          = File::Temp->newdir('lintian-po-debconf-XXXXXX',TMPDIR => 1);
+        my $abs_tempdir = realpath($temp_obj->dirname)
+          or croak('Cannot resolve ' . $temp_obj->dirname . ": $!");
+        # We need an extra level of dirs, as intltool (in)directly
+        # tries to use files in ".." if they exist
+        # (e.g. ../templates.h).
+        # - In fact, we also need to copy debian/templates into
+        #   this "fake package directory", since intltool-updates
+        #   sometimes want to write files to "../templates" based
+        #   on the contents of the package.  (See #778558)
+        my $tempdir = "$abs_tempdir/po";
+        my $test_pot = "$tempdir/test.pot";
+        my $tempdir_templates = "${abs_tempdir}/templates";
+        my $d_templates = $debian_dir->resolve_path('templates');
+
+        # Create our extra level
+        mkdir($tempdir)
+          or die encode_utf8('Cannot create directory ' . $tempdir);
+
+        # Copy the templates dir because intltool-update might
+        # write to it.
+        safe_qx(
+            qw{cp -a --reflink=auto --},
+            $d_templates->unpacked_path,
+            $tempdir_templates
+        )if $d_templates;
+
+        my $error;
+        my %save = %ENV;
+        my $cwd = Cwd::getcwd;
+
+        try {
+            $ENV{INTLTOOL_EXTRACT}
+              = '/usr/share/intltool-debian/intltool-extract';
+            # use of $debian_po is safe; we accessed two children by now.
+            $ENV{srcdir} = $debian_po_dir->unpacked_path;
+
+            chdir($tempdir)
+              or die encode_utf8('Cannot change directory ' . $tempdir);
+
+            # generate a "test.pot" in a tempdir
+            my @intltool = (
+                '/usr/share/intltool-debian/intltool-update',
+                '--gettext-package=test','--pot'
+            );
+            safe_qx(@intltool);
+            die encode_utf8("system @intltool failed: $?")
+              if $?;
+
+        } catch {
+            # catch any error
+            $error = $@;
+
+        } finally {
+            # restore environment
+            %ENV = %save;
+
+            # restore working directory
+            chdir($cwd)
+              or die encode_utf8('Cannot change directory ' . $cwd);
+        }
+
+        # output could be helpful to user but is currently not printed
+
+        if ($error) {
+            $self->pointed_hint('invalid-potfiles-in',
+                $potfiles_in_path->pointer);
+            return;
+        }
+
+        # throw away output on the following commands
+        $error = undef;
+
+        try {
+            # compare our "test.pot" with the existing "templates.pot"
+            my @testleft = (
+                'msgcmp', '--use-untranslated',
+                $test_pot, $templ_pot_path->unpacked_path
+            );
+            safe_qx(@testleft);
+            die encode_utf8("system @testleft failed: $?")
+              if $?;
+
+            # is this not equivalent to the previous command? - FL
+            my @testright = (
+                'msgcmp', '--use-untranslated',
+                $templ_pot_path->unpacked_path, $test_pot
+            );
+            safe_qx(@testright);
+            die encode_utf8("system @testright failed: $?")
+              if $?;
+
+        } catch {
+            # catch any error
+            $error = $@;
+        }
+
+        $self->pointed_hint('newer-debconf-templates',$templ_pot_path->pointer)
+          if length $error;
+    }
+
+    return
+      unless $debian_po_dir;
+
+    for my $po_item ($debian_po_dir->children) {
+
+        next
+          unless $po_item->basename =~ m/\.po$/ || $po_item->is_dir;
+
+        $self->pointed_hint('misnamed-po-file', $po_item->pointer)
+          unless (
+            $po_item->basename =~ /^[a-z]{2,3}(_[A-Z]{2})?(?:\@[^\.]+)?\.po$/);
+
+        next
+          unless $po_item->is_open_ok;
+
+        my $bytes = $po_item->bytes;
+
+        $self->pointed_hint('debconf-translation-using-general-list',
+            $po_item->pointer)
+          if $bytes =~ /Language\-Team:.*debian-i18n\@lists\.debian\.org/i;
+
+        unless ($bytes =~ /^msgstr/m) {
+
+            $self->pointed_hint('invalid-po-file', $po_item->pointer);
+            next;
+        }
+
+        if ($bytes =~ /charset=(.*?)\\n/) {
+
+            my $charset = ($1 eq 'CHARSET' ? $EMPTY : $1);
+
+            $self->pointed_hint('unknown-encoding-in-po-file',
+                $po_item->pointer)
+              unless length $charset;
+        }
+
+        my $error;
+
+        my $stats;
+
+        delete local $ENV{$_}
+          for grep { $_ ne 'PATH' && $_ ne 'TMPDIR' } keys %ENV;
+        local $ENV{LC_ALL} = 'C';
+
+        my @command = (
+            'msgfmt', '-o', '/dev/null', '--statistics',
+            $po_item->unpacked_path
+        );
+
+        run3(\@command, \undef, \undef, \$stats);
+
+        $self->pointed_hint('invalid-po-file', $po_item->pointer)
+          if $?;
+
+        $stats //= $EMPTY;
+
+        $full_translation = 1
+          if $stats =~ m/^\w+ \w+ \w+\.$/;
+    }
+
+    $self->hint('no-complete-debconf-translation')
+      if !$full_translation;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Readme.pm b/lib/Lintian/Check/Debian/Readme.pm
new file mode 100644
index 0000000..c8fd030
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Readme.pm
@@ -0,0 +1,176 @@
+# debian/readme -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Readme;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Spelling qw(check_spelling);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $VERTICAL_BAR => q{|};
+
+sub spelling_tag_emitter {
+    my ($self, $tag_name, $item, @orig_args) = @_;
+
+    my $pointer = $item->pointer($.);
+
+    return sub {
+        return $self->pointed_hint($tag_name, $pointer, @orig_args, @_);
+    };
+}
+
+sub open_readme {
+    my ($pkg_name, $processable) = @_;
+
+    my $doc_dir
+      = $processable->installed->resolve_path("usr/share/doc/${pkg_name}/");
+
+    if (defined $doc_dir) {
+
+        for my $name (
+            qw(README.Debian.gz README.Debian README.debian.gz README.debian)){
+
+            my $path = $doc_dir->child($name);
+
+            next
+              unless $path && $path->is_open_ok;
+
+            if ($name =~ m/\.gz$/) {
+                open(my $fd, '<:gzip', $path->unpacked_path)
+                  or die encode_utf8('Cannot open ' . $path->unpacked_path);
+
+                return $fd;
+            }
+
+            open(my $fd, '<', $path->unpacked_path)
+              or die encode_utf8('Cannot open ' . $path->unpacked_path);
+
+            return $fd;
+        }
+    }
+
+    return undef;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $pkg_name = $self->processable->name;
+    my $group = $self->group;
+
+    my $doc_dir
+      = $self->processable->installed->resolve_path(
+        "usr/share/doc/${pkg_name}/");
+
+    return
+      unless defined $doc_dir;
+
+    my $item;
+    my $fd;
+
+    for my $name (
+        qw(README.Debian.gz README.Debian README.debian.gz README.debian)){
+
+        $item = $doc_dir->child($name);
+
+        next
+          unless $item && $item->is_open_ok;
+
+        if ($name =~ m/\.gz$/) {
+            open($fd, '<:gzip', $item->unpacked_path)
+              or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+            last;
+        }
+
+        open($fd, '<', $item->unpacked_path)
+          or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+        last;
+    }
+
+    return
+      unless defined $item
+      && defined $fd;
+
+    my $readme = $EMPTY;
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        my $pointer = $item->pointer($position);
+
+        $self->pointed_hint('readme-debian-mentions-usr-doc', $pointer)
+          if $line =~ m{ /usr/doc \b }x;
+
+        $readme .= $line;
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    my @template =(
+        'Comments regarding the Package',
+        'So far nothing to say',
+        '<possible notes regarding this package - if none, delete this file>',
+        'Automatically generated by debmake'
+    );
+
+    my $regex = join($VERTICAL_BAR, @template);
+
+    if ($readme =~ m/$regex/i) {
+        $self->pointed_hint('readme-debian-contains-debmake-template',
+            $item->pointer);
+
+    } elsif ($readme =~ m/^\s*-- [^<]*<([^> ]+.\@[^>.]*)>/m) {
+
+        my $address = $1;
+
+        $self->pointed_hint('readme-debian-contains-invalid-email-address',
+            $item->pointer, $address);
+    }
+
+    check_spelling($self->data,$readme,$group->spelling_exceptions,
+        $self->spelling_tag_emitter('spelling-error-in-readme-debian', $item));
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Rules.pm b/lib/Lintian/Check/Debian/Rules.pm
new file mode 100644
index 0000000..ffae6cb
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Rules.pm
@@ -0,0 +1,671 @@
+# debian/rules -- lintian check script -*- perl -*-
+
+# Copyright (C) 2006 Russ Allbery <rra@debian.org>
+# Copyright (C) 2005 Rene van Bevern <rvb@pro-linux.de>
+# Copyright (C) 2019-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+package Lintian::Check::Debian::Rules;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use List::Compare;
+use List::SomeUtils qw(any none uniq);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $PERCENT => q{%};
+
+my @py3versions = qw(3.4 3.5 3.6 3.7);
+
+my $PYTHON_DEPEND= 'python2:any | python2-dev:any';
+my $PYTHON3_DEPEND
+  = 'python3:any | python3-dev:any | python3-all:any | python3-all-dev:any';
+my $PYTHON2X_DEPEND = 'python2.7:any | python2.7-dev:any';
+my $PYTHON3X_DEPEND
+  = join(' | ',map { "python${_}:any | python${_}-dev:any" } @py3versions);
+my $ANYPYTHON_DEPEND
+  = "$PYTHON_DEPEND | $PYTHON2X_DEPEND | $PYTHON3_DEPEND | $PYTHON3X_DEPEND";
+my $PYTHON3_ALL_DEPEND
+  = 'python3-all:any | python3-all-dev:any | python3-all-dbg:any';
+
+my %TAG_FOR_POLICY_TARGET = (
+    build => 'debian-rules-missing-required-target',
+    binary => 'debian-rules-missing-required-target',
+    'binary-arch' => 'debian-rules-missing-required-target',
+    'binary-indep' => 'debian-rules-missing-required-target',
+    clean => 'debian-rules-missing-required-target',
+    'build-arch' => 'debian-rules-missing-required-target',
+    'build-indep' => 'debian-rules-missing-required-target'
+);
+
+# Rules about required debhelper command ordering.  Each command is put into a
+# class and the tag is issued if they're called in the wrong order for the
+# classes.  Unknown commands won't trigger this flag.
+my %debhelper_order = (
+    dh_makeshlibs => 1,
+    dh_shlibdeps  => 2,
+    dh_installdeb => 2,
+    dh_gencontrol => 2,
+    dh_builddeb   => 3
+);
+
+sub source {
+    my ($self) = @_;
+
+    my $debian_dir = $self->processable->patched->resolve_path('debian');
+
+    my $rules;
+    $rules = $debian_dir->child('rules')
+      if defined $debian_dir;
+
+    return
+      unless defined $rules;
+
+    # Policy could be read as allowing debian/rules to be a symlink to
+    # some other file, and in a native Debian package it could be a
+    # symlink to a file that we didn't unpack.
+    $self->pointed_hint('debian-rules-is-symlink', $rules->pointer)
+      if $rules->is_symlink;
+
+    # dereference symbolic links
+    $rules = $rules->follow;
+
+    return
+      unless defined $rules;
+
+    $self->pointed_hint('debian-rules-not-executable', $rules->pointer)
+      unless $rules->is_executable;
+
+    my $KNOWN_MAKEFILES= $self->data->load('rules/known-makefiles', '\|\|');
+    my $DEPRECATED_MAKEFILES= $self->data->load('rules/deprecated-makefiles');
+
+    my $architecture = $self->processable->fields->value('Architecture');
+
+    # If the version field is missing, we assume a neutral non-native one.
+    my $version = $self->processable->fields->value('Version') || '0-1';
+
+    # Check for required #!/usr/bin/make -f opening line.  Allow -r or -e; a
+    # strict reading of Policy doesn't allow either, but they seem harmless.
+    $self->pointed_hint('debian-rules-not-a-makefile', $rules->pointer)
+      unless $rules->hashbang =~ m{^/usr/bin/make\s+-[re]?f[re]?$};
+
+   # Certain build tools must be listed in Build-Depends even if there are no
+   # arch-specific packages because they're required in order to run the clean
+   # rule.  (See Policy 7.6.)  The following is a list of package dependencies;
+   # regular expressions that, if they match anywhere in the debian/rules file,
+   # say that this package is allowed (and required) in Build-Depends; and
+   # optional tags to use for reporting the problem if some information other
+   # than the default is required.
+    my %GLOBAL_CLEAN_DEPENDS = (
+        'ant:any' => [qr{^include\s*/usr/share/cdbs/1/rules/ant\.mk}],
+        'cdbs:any' => [
+            qr{^include\s+/usr/share/cdbs/},
+            qr{^include\s+/usr/share/R/debian/r-cran\.mk}
+        ],
+        'dbs:any' => [qr{^include\s+/usr/share/dbs/}],
+        'dh-make-php:any' => [qr{^include\s+/usr/share/cdbs/1/class/pear\.mk}],
+        'debhelper:any | debhelper-compat:any' =>[
+            qr{^include\s+/usr/share/cdbs/1/rules/debhelper\.mk},
+            qr{^include\s+/usr/share/R/debian/r-cran\.mk}
+        ],
+        'dpatch:any' => [
+            qr{^include\s+/usr/share/dpatch/},
+            qr{^include\s+/usr/share/cdbs/1/rules/dpatch\.mk}
+        ],
+        'gnome-pkg-tools:any | dh-sequence-gnome:any' =>
+          [qr{^include\s+/usr/share/gnome-pkg-tools/}],
+        'quilt:any' => [
+            qr{^include\s+/usr/share/quilt/},
+            qr{^include\s+/usr/share/cdbs/1/rules/patchsys-quilt\.mk}
+        ],
+        'mozilla-devscripts:any' =>
+          [qr{^include\s+/usr/share/mozilla-devscripts/}],
+        'ruby-pkg-tools:any' =>
+          [qr{^include\s+/usr/share/ruby-pkg-tools/1/class/}],
+        'r-base-dev:any' => [qr{^include\s+/usr/share/R/debian/r-cran\.mk}],
+        $ANYPYTHON_DEPEND =>[qr{/usr/share/cdbs/1/class/python-distutils\.mk}],
+    );
+
+  # A list of packages; regular expressions that, if they match anywhere in the
+  # debian/rules file, this package must be listed in either Build-Depends or
+  # Build-Depends-Indep as appropriate; and optional tags as above.
+    my %GLOBAL_DEPENDS = (
+        'dh-ocaml:any, ocaml-nox:any | ocaml:any' =>
+          [qr/^\t\s*dh_ocaml(?:init|doc)\s/],
+        'debhelper:any | debhelper-compat:any | dh-autoreconf:any' =>
+          [qr/^\t\s*dh_autoreconf(?:_clean)?\s/],
+    );
+
+ # Similarly, this list of packages, regexes, and optional tags say that if the
+ # regex matches in one of clean, build-arch, binary-arch, or a rule they
+ # depend on, this package is allowed (and required) in Build-Depends.
+    my %RULE_CLEAN_DEPENDS =(
+        'ant:any' => [qr/^\t\s*(\S+=\S+\s+)*ant\s/],
+        'debhelper:any | debhelper-compat:any' =>
+          [qr/^\t\s*dh_(?!autoreconf).+/],
+        'dh-ocaml:any, ocaml-nox:any | ocaml:any' =>[qr/^\t\s*dh_ocamlinit\s/],
+        'dpatch:any' => [qr/^\t\s*(\S+=\S+\s+)*dpatch\s/],
+        'po-debconf:any' => [qr/^\t\s*debconf-updatepo\s/],
+        $PYTHON_DEPEND => [qr/^\t\s*python\s/],
+        $PYTHON3_DEPEND => [qr/^\t\s*python3\s/],
+        $ANYPYTHON_DEPEND => [qr/\ssetup\.py\b/],
+        'quilt:any' => [qr/^\t\s*(\S+=\S+\s+)*quilt\s/],
+    );
+
+    my $build_all = $self->processable->relation('Build-Depends-All');
+    my $build_all_norestriction
+      = $self->processable->relation_norestriction('Build-Depends-All');
+    my $build_regular = $self->processable->relation('Build-Depends');
+    my $build_indep   = $self->processable->relation('Build-Depends-Indep');
+
+    # no need to look for items we have
+    delete %GLOBAL_DEPENDS{$_}
+      for grep { $build_regular->satisfies($_) } keys %GLOBAL_DEPENDS;
+    delete %GLOBAL_CLEAN_DEPENDS{$_}
+      for grep { $build_regular->satisfies($_) } keys %GLOBAL_CLEAN_DEPENDS;
+    delete %RULE_CLEAN_DEPENDS{$_}
+      for grep { $build_regular->satisfies($_) } keys %RULE_CLEAN_DEPENDS;
+
+    my @needed;
+    my @needed_clean;
+
+    # Scan debian/rules.  We would really like to let make do this for
+    # us, but unfortunately there doesn't seem to be a way to get make
+    # to syntax-check and analyze a makefile without running at least
+    # $(shell) commands.
+    #
+    # We skip some of the rule analysis if debian/rules includes any
+    # other files, since to chase all includes we'd have to have all
+    # of its build dependencies installed.
+    local $_ = undef;
+
+    my @arch_rules = map { qr/^$_$/ } qw(clean binary-arch build-arch);
+    my @indep_rules = qw(build build-indep binary-indep);
+    my @current_targets;
+    my %rules_per_target;
+    my %debhelper_group;
+    my %seen;
+    my %overridden;
+    my $maybe_skipping;
+    my @conditionals;
+    my %variables;
+    my $includes = 0;
+
+    my $contents = $rules->decoded_utf8;
+    return
+      unless length $contents;
+
+    my @lines = split(/\n/, $contents);
+
+    my $continued = $EMPTY;
+    my $position = 1;
+
+    for my $line (@lines) {
+
+        my $pointer = $rules->pointer($position);
+
+        $self->pointed_hint('debian-rules-is-dh_make-template', $pointer)
+          if $line =~ m/dh_make generated override targets/;
+
+        next
+          if $line =~ /^\s*\#/;
+
+        if (length $continued) {
+            $line = $continued . $line;
+            $continued = $EMPTY;
+        }
+
+        if ($line =~ s/\\$//) {
+            $continued = $line;
+            next;
+        }
+
+        if ($line =~ /^\s*[s-]?include\s+(\S++)/){
+            my $makefile = $1;
+            my $targets = $KNOWN_MAKEFILES->value($makefile);
+            if (defined $targets){
+                for my $target (split /\s*+,\s*+/, $targets){
+                    $seen{$target}++ if exists $TAG_FOR_POLICY_TARGET{$target};
+                }
+            } else {
+                $includes = 1;
+            }
+
+            $self->pointed_hint('debian-rules-uses-deprecated-makefile',
+                $pointer, $makefile)
+              if $DEPRECATED_MAKEFILES->recognizes($makefile);
+        }
+
+        # problems occurring only outside targets
+        unless (%seen) {
+
+          # Check for DH_COMPAT settings outside of any rule, which are now
+          # deprecated.  It's a bit easier structurally to do this here than in
+          # debhelper.
+            $self->pointed_hint('debian-rules-sets-DH_COMPAT', $pointer)
+              if $line =~ /^\s*(?:export\s+)?DH_COMPAT\s*:?=/;
+
+            $self->pointed_hint('debian-rules-sets-DEB_BUILD_OPTIONS',$pointer)
+              if $line =~ /^\s*(?:export\s+)?DEB_BUILD_OPTIONS\s*:?=/;
+
+            if (
+                $line =~m{^
+                \s*(?:export\s+)?
+                (DEB_(?:HOST|BUILD|TARGET)_(?:ARCH|MULTIARCH|GNU)[A-Z_]*)\s*:?=
+            }x
+            ) {
+                my $variable = $1;
+
+                $self->pointed_hint(
+                    'debian-rules-sets-dpkg-architecture-variable',
+                    $pointer, $variable);
+            }
+
+        }
+
+        if (   $line =~ /^\t\s*-(?:\$[\(\{]MAKE[\}\)]|make)\s.*(?:dist)?clean/s
+            || $line
+            =~ /^\t\s*(?:\$[\(\{]MAKE[\}\)]|make)\s(?:.*\s)?-(\w*)i.*(?:dist)?clean/s
+        ) {
+            my $flags = $1 // $EMPTY;
+
+            # Ignore "-C<dir>" (#671537)
+            $self->pointed_hint('debian-rules-ignores-make-clean-error',
+                $pointer)
+              unless $flags =~ /^C/;
+        }
+
+        if ($line
+            =~ m{dh_strip\b.*(--(?:ddeb|dbgsym)-migration=(?:'[^']*'|\S*))}) {
+
+            my $context = $1;
+
+            $self->pointed_hint('debug-symbol-migration-possibly-complete',
+                $pointer, $context);
+        }
+
+        $self->pointed_hint('debian-rules-passes-version-info-to-dh_shlibdeps',
+            $pointer)
+          if $line =~ m{dh_shlibdeps\b.*(?:--version-info|-V)\b};
+
+        $self->pointed_hint('debian-rules-updates-control-automatically',
+            $pointer)
+          if $line =~ m{^\s*DEB_AUTO_UPDATE_DEBIAN_CONTROL\s*=\s*yes};
+
+        $self->pointed_hint('debian-rules-uses-deb-build-opts', $pointer)
+          if $line =~ m{\$[\(\{]DEB_BUILD_OPTS[\)\}]};
+
+        if ($line =~ m{^\s*DH_EXTRA_ADDONS\s*=\s*(.*)$}) {
+
+            my $context = $1;
+
+            $self->pointed_hint('debian-rules-should-not-use-DH_EXTRA_ADDONS',
+                $pointer, $context);
+        }
+
+        $self->pointed_hint('debian-rules-uses-wrong-environment-variable',
+            $pointer)
+          if $line =~ m{\bDEB_[^_ \t]+FLAGS_(?:SET|APPEND)\b};
+
+        $self->pointed_hint('debian-rules-calls-pwd', $pointer)
+          if $line =~ m{\$[\(\{]PWD[\)\}]};
+
+        $self->pointed_hint(
+            'debian-rules-should-not-use-sanitize-all-buildflag',$pointer)
+          if $line
+          =~ m{^\s*(?:export\s+)?DEB_BUILD_MAINT_OPTIONS\s*:?=.*\bsanitize=\+all\b};
+
+        $self->pointed_hint('debian-rules-uses-special-shell-variable',
+            $pointer)
+          if $line =~ m{\$[\(\{]_[\)\}]};
+
+        if ($line =~ m{(dh_builddeb\b.*--.*-[zZS].*)$}) {
+
+            my $context = $1;
+
+            $self->pointed_hint('custom-compression-in-debian-rules',
+                $pointer, $context);
+        }
+
+        if ($line =~ m{(py3versions\s+([\w\-\s]*--installed|-\w*i\w*))}) {
+
+            my $context = $1;
+
+            $self->pointed_hint('debian-rules-uses-installed-python-versions',
+                $pointer, $context);
+        }
+
+        $self->pointed_hint('debian-rules-uses-as-needed-linker-flag',$pointer)
+          if $line =~ /--as-needed/ && $line !~ /--no-as-needed/;
+
+        if ($line =~ /(py3versions\s+([\w\-\s]*--supported|-\w*s\w*))/) {
+
+            my $context = $1;
+
+            $self->pointed_hint(
+'debian-rules-uses-supported-python-versions-without-python-all-build-depends',
+                $pointer,
+                $context
+            )unless $build_all_norestriction->satisfies($PYTHON3_ALL_DEPEND);
+        }
+
+        # General assignment - save the variable
+        if ($line =~ /^\s*(?:\S+\s+)*?(\S+)\s*[:\?\+]?=\s*(.*+)?$/s) {
+            # This is far too simple from a theoretical PoV, but should do
+            # rather well.
+            my ($var, $value) = ($1, $2);
+            $variables{$var} = $value;
+
+            $self->pointed_hint('unnecessary-source-date-epoch-assignment',
+                $pointer)
+              if $var eq 'SOURCE_DATE_EPOCH'
+              && !$build_all->satisfies(
+                'dpkg-dev:any (>= 1.18.8) | debhelper:any (>= 10.10)');
+        }
+
+        # Keep track of whether this portion of debian/rules may be optional
+        if ($line =~ /^ifn?(?:eq|def)\s(.*)/) {
+            push(@conditionals, $1);
+            $maybe_skipping++;
+
+        } elsif ($line =~ /^endif\s/) {
+            $maybe_skipping--;
+        }
+
+        unless ($maybe_skipping) {
+
+            for my $prerequisite (keys %GLOBAL_DEPENDS) {
+
+                my @patterns = @{ $GLOBAL_DEPENDS{$prerequisite} };
+
+                push(@needed, $prerequisite)
+                  if any { $line =~ $_ } @patterns;
+            }
+
+            for my $prerequisite (keys %GLOBAL_CLEAN_DEPENDS) {
+
+                my @patterns = @{ $GLOBAL_CLEAN_DEPENDS{$prerequisite} };
+
+                if (any { $line =~ $_ } @patterns) {
+
+                    push(@needed, $prerequisite);
+                    push(@needed_clean, $prerequisite);
+                }
+            }
+        }
+
+        # Listing a rule as a dependency of .PHONY is sufficient to make it
+        # present for the purposes of GNU make and therefore the Policy
+        # requirement.
+        if ($line =~ /^(?:[^:]+\s)?\.PHONY(?:\s[^:]+)?:(.+)/s) {
+
+            my @targets = split($SPACE, $1);
+            for my $target (@targets) {
+                # Is it $(VAR) ?
+                if ($target =~ /^\$[\(\{]([^\)\}]++)[\)\}]$/) {
+                    my $name = $1;
+                    my $val = $variables{$name};
+                    if ($val) {
+                        # we think we know what it will expand to - note
+                        # we ought to "delay" it was a "=" variable rather
+                        # than ":=" or "+=".
+
+                   # discards empty elements at end, effectively trimming right
+                        for (split(/\s+/, $val)) {
+                            $seen{$target}++
+                              if exists $TAG_FOR_POLICY_TARGET{$target};
+                        }
+                        last;
+                    }
+                    # We don't know, so just mark the target as seen.
+                }
+                $seen{$target}++
+                  if exists $TAG_FOR_POLICY_TARGET{$target};
+            }
+
+            #.PHONY implies the rest will not match
+            next;
+        }
+
+        if (  !$includes
+            && $line
+            =~ /dpkg-parsechangelog.*(?:Source|Version|Date|Timestamp)/s) {
+
+            $self->pointed_hint('debian-rules-parses-dpkg-parsechangelog',
+                $pointer);
+        }
+
+        if ($line !~ /^ifn?(?:eq|def)\s/ && $line =~ /^([^\s:][^:]*):+(.*)/s) {
+            my ($target_names, $target_dependencies) = ($1, $2);
+            @current_targets = split $SPACE, $target_names;
+
+            my @quoted = map { quotemeta } split($SPACE, $target_dependencies);
+            s/\\\$\\\([^\):]+\\:([^=]+)\\=([^\)]+)\1\\\)/$2.*/g for @quoted;
+
+            my @depends = map { qr/^$_$/ } @quoted;
+
+            for my $target (@current_targets) {
+                $overridden{$1} = $position if $target =~ m/override_(.+)/;
+                if ($target =~ /%/) {
+                    my $pattern = quotemeta $target;
+                    $pattern =~ s/\\%/.*/g;
+                    for my $rulebypolicy (keys %TAG_FOR_POLICY_TARGET) {
+                        $seen{$rulebypolicy}++ if $rulebypolicy =~ m/$pattern/;
+                    }
+                } else {
+                    # Is it $(VAR) ?
+                    if ($target =~ m/^\$[\(\{]([^\)\}]++)[\)\}]$/) {
+                        my $name = $1;
+                        my $val = $variables{$name};
+                        if ($val) {
+                            # we think we know what it will expand to - note
+                            # we ought to "delay" it was a "=" variable rather
+                            # than ":=" or "+=".
+                            local $_ = undef;
+
+                   # discards empty elements at end, effectively trimming right
+                            for (split(/\s+/, $val)) {
+                                $seen{$_}++
+                                  if exists $TAG_FOR_POLICY_TARGET{$_};
+                            }
+                            last;
+                        }
+                        # We don't know, so just mark the target as seen.
+                    }
+                    $seen{$target}++ if exists $TAG_FOR_POLICY_TARGET{$target};
+                }
+                if (any { $target =~ /$_/ } @arch_rules) {
+                    push(@arch_rules, @depends);
+                }
+            }
+            undef %debhelper_group;
+
+        } elsif ($line =~ /^define /) {
+            # We don't want to think the body of the define is part of
+            # the previous rule or we'll get false positives on tags
+            # like binary-arch-rules-but-pkg-is-arch-indep.  Treat a
+            # define as the end of the current rule, although that
+            # isn't very accurate either.
+            @current_targets = ();
+
+        } else {
+            # If we have non-empty, non-comment lines, store them for
+            # all current targets and check whether debhelper programs
+            # are called in a reasonable order.
+            if ($line =~ /^\s+[^\#]/) {
+                my ($arch, $indep) = (0, 0);
+                for my $target (@current_targets) {
+                    $rules_per_target{$target} ||= [];
+                    push(@{$rules_per_target{$target}}, $line);
+
+                    $arch = 1
+                      if any { $target =~ /$_/ } @arch_rules;
+
+                    $indep = 1
+                      if any { $target eq $_ } @indep_rules;
+
+                    $indep = 1
+                      if $target eq $PERCENT;
+
+                    $indep = 1
+                      if $target =~ /^override_/;
+                }
+
+                if (!$maybe_skipping && ($arch || $indep)) {
+
+                    for my $prerequisite (keys %RULE_CLEAN_DEPENDS) {
+
+                        my @patterns = @{ $RULE_CLEAN_DEPENDS{$prerequisite} };
+
+                        if (any { $line =~ $_ } @patterns) {
+
+                            push(@needed, $prerequisite);
+                            push(@needed_clean, $prerequisite)
+                              if $arch;
+                        }
+                    }
+                }
+
+                if ($line =~ /^\s+(dh_\S+)\b/ && $debhelper_order{$1}) {
+                    my $command = $1;
+                    my ($package) = ($line =~ /\s(?:-p|--package=)(\S+)/);
+                    $package ||= $EMPTY;
+                    my $group = $debhelper_order{$command};
+                    $debhelper_group{$package} ||= 0;
+
+                    if ($group < $debhelper_group{$package}) {
+
+                        $self->pointed_hint(
+                            'debian-rules-calls-debhelper-in-odd-order',
+                            $pointer, $command);
+
+                    } else {
+                        $debhelper_group{$package} = $group;
+                    }
+                }
+            }
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    my @missing_targets;
+    @missing_targets = grep { !$seen{$_} } keys %TAG_FOR_POLICY_TARGET
+      unless $includes;
+
+    $self->pointed_hint($TAG_FOR_POLICY_TARGET{$_}, $rules->pointer, $_)
+      for @missing_targets;
+
+    # Make sure we have no content for binary-arch if we are arch-indep:
+    $rules_per_target{'binary-arch'} ||= [];
+    if ($architecture eq 'all' && scalar @{$rules_per_target{'binary-arch'}}) {
+
+        my $nonempty = 0;
+        for my $rule (@{$rules_per_target{'binary-arch'}}) {
+            # dh binary-arch is actually a no-op if there is no
+            # Architecture: any package in the control file
+            $nonempty = 1
+              unless $rule =~ /^\s*dh\s+(?:binary-arch|\$\@)/;
+        }
+
+        $self->pointed_hint('binary-arch-rules-but-pkg-is-arch-indep',
+            $rules->pointer)
+          if $nonempty;
+    }
+
+    for my $cmd (qw(dh_clean dh_fixperms)) {
+        for my $suffix ($EMPTY, '-indep', '-arch') {
+
+            my $memorized_position = $overridden{"$cmd$suffix"};
+            next
+              unless defined $memorized_position;
+
+            $self->pointed_hint(
+                "override_$cmd-does-not-call-$cmd",
+                $rules->pointer($memorized_position)
+              )
+              if none { m/^\t\s*-?($cmd\b|\$\(overridden_command\))/ }
+              @{$rules_per_target{"override_$cmd$suffix"}};
+        }
+    }
+
+    if (my $memorized_position = $overridden{'dh_auto_test'}) {
+
+        my @rules = grep {
+            !m{^\t\s*[\:\[]}
+              && !m{^\s*$}
+              && !m{\bdh_auto_test\b}
+              && !
+m{^\t\s*[-@]?(?:(?:/usr)?/bin/)?(?:cp|chmod|echo|ln|mv|mkdir|rm|test|true)}
+        } @{$rules_per_target{'override_dh_auto_test'}};
+
+        $self->pointed_hint(
+            'override_dh_auto_test-does-not-check-DEB_BUILD_OPTIONS',
+            $rules->pointer($memorized_position))
+          if @rules and none { m/(DEB_BUILD_OPTIONS|nocheck)/ } @conditionals;
+    }
+
+    $self->pointed_hint(
+        'debian-rules-contains-unnecessary-get-orig-source-target',
+        $rules->pointer)
+      if any { m/^\s+uscan\b/ } @{$rules_per_target{'get-orig-source'}};
+
+    my @clean_in_indep
+      = grep { $build_indep->satisfies($_) } uniq @needed_clean;
+    $self->pointed_hint(
+        'missing-build-depends-for-clean-target-in-debian-rules',
+        $rules->pointer, "(does not satisfy $_)")
+      for @clean_in_indep;
+
+    # another check complains when debhelper is missing from d/rules
+    my $combined_lc = List::Compare->new(\@needed, ['debhelper:any']);
+
+    my @still_missing
+      = grep { !$build_all_norestriction->satisfies($_) }
+      $combined_lc->get_Lonly;
+
+    $self->pointed_hint('rules-require-build-prerequisite',
+        $rules->pointer, "(does not satisfy $_)")
+      for @still_missing;
+
+    $self->pointed_hint('debian-rules-should-not-set-CFLAGS-from-noopt',
+        $rules->pointer)
+      if $contents
+      =~ m{^ ifn?eq \s+ [(] , \$ [(] findstring \s+ noopt , \$ [(] DEB_BUILD_OPTIONS [)] [)] [)] \n+
+                        \t+ CFLAGS \s+ \+ = \s+ -O[02] \n+
+                        else \n+
+                        \t+ CFLAGS \s+ \+ = \s+ -O[02] \n+
+                        endif $}xsm;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Rules/DhSequencer.pm b/lib/Lintian/Check/Debian/Rules/DhSequencer.pm
new file mode 100644
index 0000000..bc2b239
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Rules/DhSequencer.pm
@@ -0,0 +1,65 @@
+# debian/rules/dh-sequencer -- lintian check script -*- perl -*-
+
+# Copyright (C) 2019 Felix Lechner
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Rules::DhSequencer;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->name eq 'debian/rules';
+
+    my $bytes = $item->bytes;
+
+    # strip comments (see #960485)
+    $bytes =~ s/^\h#.*\R?//mg;
+
+    my $plain = qr/\$\@/;
+    my $curly = qr/\$\{\@\}/;
+    my $asterisk = qr/\$\*/;
+    my $parentheses = qr/\$\(\@\)/;
+    my $rule_altern = qr/(?:$plain|$curly|$asterisk|$parentheses)/;
+    my $rule_target = qr/(?:$rule_altern|'$rule_altern'|"$rule_altern")/;
+
+    $self->pointed_hint('no-dh-sequencer', $item->pointer)
+      unless $bytes =~ /^\t+(?:[\+@-])?(?:[^=]+=\S+ )?dh[ \t]+$rule_target/m
+      || $bytes =~ m{^\s*include\s+/usr/share/cdbs/1/class/hlibrary.mk\s*$}m
+      || $bytes =~ m{\bDEB_CABAL_PACKAGE\b};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Shlibs.pm b/lib/Lintian/Check/Debian/Shlibs.pm
new file mode 100644
index 0000000..8e755d9
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Shlibs.pm
@@ -0,0 +1,656 @@
+# debian/shlibs -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2018-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Shlibs;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use File::Basename;
+use List::Compare;
+use List::SomeUtils qw(any none uniq);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $EQUALS => q{=};
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+my @known_meta_labels = qw{
+  Build-Depends-Package
+  Build-Depends-Packages
+  Ignore-Blacklist-Groups
+};
+
+has soname_by_filename => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %soname_by_filename;
+        for my $item (@{$self->processable->installed->sorted_list}) {
+
+            $soname_by_filename{$item->name}= $item->elf->{SONAME}[0]
+              if exists $item->elf->{SONAME};
+        }
+
+        return \%soname_by_filename;
+    }
+);
+
+has shlibs_positions_by_pretty_soname => (is => 'rw', default => sub { {} });
+has symbols_positions_by_soname => (is => 'rw', default => sub { {} });
+
+sub installable {
+    my ($self) = @_;
+
+    $self->check_shlibs_file;
+    $self->check_symbols_file;
+
+    my @pretty_sonames_from_shlibs
+      = keys %{$self->shlibs_positions_by_pretty_soname};
+    my @pretty_sonames_from_symbols
+      = map { human_soname($_) } keys %{$self->symbols_positions_by_soname};
+
+    # Compare the contents of the shlibs and symbols control files, but exclude
+    # from this check shared libraries whose SONAMEs has no version.  Those can
+    # only be represented in symbols files and aren't expected in shlibs files.
+    my $extra_lc = List::Compare->new(\@pretty_sonames_from_symbols,
+        \@pretty_sonames_from_shlibs);
+
+    if (%{$self->shlibs_positions_by_pretty_soname}) {
+
+        my @versioned = grep { m{ } } $extra_lc->get_Lonly;
+
+        $self->hint('symbols-for-undeclared-shared-library', $_)for @versioned;
+    }
+
+    return;
+}
+
+sub check_shlibs_file {
+    my ($self) = @_;
+
+    my @ldconfig_folders = @{$self->data->architectures->ldconfig_folders};
+
+    # Libraries with no version information can't be represented by
+    # the shlibs format (but can be represented by symbols).  We want
+    # to warn about them if they appear in public directories.  If
+    # they're in private directories, assume they're plugins or
+    # private libraries and are safe.
+    my @unversioned_libraries;
+    for my $file_name (keys %{$self->soname_by_filename}) {
+
+        my $pretty_soname
+          = human_soname($self->soname_by_filename->{$file_name});
+        next
+          if $pretty_soname =~ m{ };
+
+        push(@unversioned_libraries, $file_name);
+        $self->hint('shared-library-lacks-version', $file_name, $pretty_soname)
+          if any { (dirname($file_name) . $SLASH) eq $_ } @ldconfig_folders;
+    }
+
+    my $versioned_lc = List::Compare->new([keys %{$self->soname_by_filename}],
+        \@unversioned_libraries);
+    my @versioned_libraries = $versioned_lc->get_Lonly;
+
+    # 4th step: check shlibs control file
+    # $package_version may be undef in very broken packages
+    my $shlibs_file = $self->processable->control->lookup('shlibs');
+    $shlibs_file = undef
+      if defined $shlibs_file && !$shlibs_file->is_file;
+
+    # no shared libraries included in package, thus shlibs control
+    # file should not be present
+    $self->pointed_hint('empty-shlibs', $shlibs_file->pointer)
+      if defined $shlibs_file && !@versioned_libraries;
+
+    # shared libraries included, thus shlibs control file has to exist
+    for my $file_name (@versioned_libraries) {
+
+        # only public shared libraries
+        $self->hint('no-shlibs', $file_name)
+          if (any { (dirname($file_name) . $SLASH) eq $_ } @ldconfig_folders)
+          && !defined $shlibs_file
+          && $self->processable->type ne 'udeb'
+          && !is_nss_plugin($file_name);
+    }
+
+    if (@versioned_libraries && defined $shlibs_file) {
+
+        my @shlibs_prerequisites;
+
+        my @lines = split(/\n/, $shlibs_file->decoded_utf8);
+
+        my $position = 1;
+        for my $line (@lines) {
+
+            next
+              if $line =~ m{^ \s* $}x
+              || $line =~ m{^ [#] }x;
+
+            # We exclude udebs from the checks for correct shared library
+            # dependencies, since packages may contain dependencies on
+            # other udeb packages.
+
+            my $udeb = $EMPTY;
+            $udeb = 'udeb: '
+              if $line =~ s/^udeb:\s+//;
+
+            my ($name, $version, @prerequisites) = split($SPACE, $line);
+            my $pretty_soname = "$udeb$name $version";
+
+            $self->shlibs_positions_by_pretty_soname->{$pretty_soname} //= [];
+            push(
+                @{$self->shlibs_positions_by_pretty_soname->{$pretty_soname}},
+                $position
+            );
+
+            push(@shlibs_prerequisites, join($SPACE, @prerequisites))
+              unless $udeb;
+
+        } continue {
+            ++$position;
+        }
+
+        my @duplicate_pretty_sonames
+          = grep { @{$self->shlibs_positions_by_pretty_soname->{$_}} > 1 }
+          keys %{$self->shlibs_positions_by_pretty_soname};
+
+        for my $pretty_soname (@duplicate_pretty_sonames) {
+
+            my $indicator
+              = $LEFT_PARENTHESIS . 'lines'
+              . $SPACE
+              . join($SPACE,
+                sort { $a <=> $b }
+                  @{$self->shlibs_positions_by_pretty_soname->{$pretty_soname}}
+              ). $RIGHT_PARENTHESIS;
+
+            $self->pointed_hint('duplicate-in-shlibs', $shlibs_file->pointer,
+                $indicator,$pretty_soname);
+        }
+
+        my @used_pretty_sonames;
+        for my $file_name (@versioned_libraries) {
+
+            my $pretty_soname
+              = human_soname($self->soname_by_filename->{$file_name});
+
+            push(@used_pretty_sonames, $pretty_soname);
+            push(@used_pretty_sonames, "udeb: $pretty_soname");
+
+            # only public shared libraries
+            $self->pointed_hint('ships-undeclared-shared-library',
+                $shlibs_file->pointer,$pretty_soname, 'for', $file_name)
+              if (any { (dirname($file_name) . $SLASH) eq $_ }
+                @ldconfig_folders)
+              && !@{$self->shlibs_positions_by_pretty_soname->{$pretty_soname}
+                  // []}
+              && !is_nss_plugin($file_name);
+        }
+
+        my $unused_lc
+          = List::Compare->new(
+            [keys %{$self->shlibs_positions_by_pretty_soname}],
+            \@used_pretty_sonames);
+
+        $self->pointed_hint('shared-library-not-shipped',
+            $shlibs_file->pointer, $_)
+          for $unused_lc->get_Lonly;
+
+        my $fields = $self->processable->fields;
+
+        # Check that all of the packages listed as dependencies in
+        # the shlibs file are satisfied by the current package or
+        # its Provides.  Normally, packages should only declare
+        # dependencies in their shlibs that they themselves can
+        # satisfy.
+        my $provides = $self->processable->name;
+        $provides
+          .= $LEFT_PARENTHESIS
+          . $EQUALS
+          . $SPACE
+          . $fields->value('Version')
+          . $RIGHT_PARENTHESIS
+          if $fields->declares('Version');
+
+        $provides
+          = $self->processable->relation('Provides')->logical_and($provides);
+
+        for my $prerequisite (uniq @shlibs_prerequisites) {
+
+            $self->pointed_hint('distant-prerequisite-in-shlibs',
+                $shlibs_file->pointer, $prerequisite)
+              unless $provides->satisfies($prerequisite);
+
+            $self->pointed_hint('outdated-relation-in-shlibs',
+                $shlibs_file->pointer, $prerequisite)
+              if $prerequisite =~ m/\(\s*[><](?![<>=])\s*/;
+        }
+    }
+
+    return;
+}
+
+sub check_symbols_file {
+    my ($self) = @_;
+
+    my @ldconfig_folders = @{$self->data->architectures->ldconfig_folders};
+    my @shared_libraries = keys %{$self->soname_by_filename};
+
+    my $fields = $self->processable->fields;
+    my $symbols_file = $self->processable->control->lookup('symbols');
+
+    if (!defined $symbols_file
+        && $self->processable->type ne 'udeb') {
+
+        for my $file_name (@shared_libraries){
+
+            my $item = $self->processable->installed->lookup($file_name);
+            next
+              unless defined $item;
+
+            my @symbols
+              = grep { $_->section eq '.text' || $_->section eq 'UND' }
+              @{$item->elf->{SYMBOLS} // []};
+
+            # only public shared libraries
+            # Skip Objective C libraries as instance/class methods do not
+            # appear in the symbol table
+            $self->hint('no-symbols-control-file', $file_name)
+              if (any { (dirname($file_name) . $SLASH) eq $_ }
+                @ldconfig_folders)
+              && (none { $_->name =~ m/^__objc_/ } @symbols)
+              && !is_nss_plugin($file_name);
+        }
+    }
+
+    return
+      unless defined $symbols_file;
+
+    # no shared libraries included in package, thus symbols
+    # control file should not be present
+    $self->pointed_hint('empty-shared-library-symbols', $symbols_file->pointer)
+      unless @shared_libraries;
+
+    # Assume the version to be a non-native version to avoid
+    # uninitialization warnings later.
+    my $package_version = $fields->value('Version') || '0-1';
+
+    my $package_version_wo_rev = $package_version;
+    $package_version_wo_rev =~ s/^ (.+) - [^-]+ $/$1/x;
+
+    my @sonames;
+    my %symbols_by_soname;
+    my %full_version_symbols_by_soname;
+    my %debian_revision_symbols_by_soname;
+    my %prerequisites_by_soname;
+    my %positions_by_soname_and_meta_label;
+    my @syntax_errors;
+    my $template_count = 0;
+
+    my @lines = split(/\n/, $symbols_file->decoded_utf8);
+
+    my $current_soname = $EMPTY;
+    my $position = 1;
+    for my $line (@lines) {
+
+        next
+          if $line =~ m{^ \s* $}x
+          || $line =~ m{^ [#] }x;
+
+        # soname, main dependency template
+        if ($line
+            =~ m{^ ([^\s|*]\S+) \s\S+\s* (?: [(] \S+\s+\S+ [)] | [#]MINVER[#] )? }x
+        ){
+
+            $current_soname = $1;
+            push(@sonames, $current_soname);
+
+            $line =~ s/^\Q$current_soname\E\s*//;
+
+            $self->symbols_positions_by_soname->{$current_soname} //= [];
+            push(
+                @{$self->symbols_positions_by_soname->{$current_soname}},
+                $position
+            );
+
+            for my $conjunctive (split(m{ \s* , \s* }x, $line)) {
+                for my $disjunctive (split(m{ \s* [|] \s* }x, $conjunctive)){
+
+                    $disjunctive
+                      =~ m{^ (\S+) ( \s* (?: [(] \S+\s+\S+ [)] | [#]MINVER[#]))? $}x;
+
+                    my $package = $1;
+                    my $version = $2 || $EMPTY;
+
+                    if (length $package) {
+                        $prerequisites_by_soname{$current_soname} //= [];
+                        push(
+                            @{$prerequisites_by_soname{$current_soname}},
+                            $package . $version
+                        );
+
+                    } else {
+                        push(@syntax_errors, $position);
+                    }
+                }
+            }
+
+            $template_count = 0;
+
+            next;
+        }
+
+        # alternative dependency template
+        if ($line
+            =~ m{^ [|] \s+\S+\s* (?: [(] \S+\s+\S+ [)] | [#]MINVER[#] )? }x) {
+
+            my $error = 0;
+
+            if (%{$positions_by_soname_and_meta_label{$current_soname} // {} }
+                || !length $current_soname) {
+
+                push(@syntax_errors, $position);
+                $error = 1;
+            }
+
+            $line =~ s{^ [|] \s* }{}x;
+
+            for my $conjunctive (split(m{ \s* , \s* }x, $line)) {
+                for my $disjunctive (split(m{ \s* [|] \s* }x, $conjunctive)) {
+
+                    $disjunctive
+                      =~ m{^ (\S+) ( \s* (?: [(] \S+ \s+ \S+ [)] | [#]MINVER[#] ) )? $}x;
+
+                    my $package = $1;
+                    my $version = $2 || $EMPTY;
+
+                    if (length $package) {
+                        $prerequisites_by_soname{$current_soname} //= [];
+                        push(
+                            @{$prerequisites_by_soname{$current_soname}},
+                            $package . $version
+                        );
+
+                    } else {
+                        push(@syntax_errors, $position)
+                          unless $error;
+
+                        $error = 1;
+                    }
+                }
+            }
+
+            $template_count++ unless $error;
+
+            next;
+        }
+
+        # meta-information
+        if ($line =~ m{^ [*] \s (\S+) : \s \S+ }x) {
+
+            my $meta_label = $1;
+
+            $positions_by_soname_and_meta_label{$current_soname}{$meta_label}
+              //= [];
+            push(
+                @{
+                    $positions_by_soname_and_meta_label{$current_soname}
+                      {$meta_label}
+                },
+                $position
+            );
+
+            push(@syntax_errors, $position)
+              if !defined $current_soname
+              || @{$symbols_by_soname{$current_soname} // [] };
+
+            next;
+        }
+
+        # Symbol definition
+        if ($line =~ m{^\s+ (\S+) \s (\S+) (?:\s (\S+ (?:\s\S+)? ) )? $}x) {
+
+            my $symbol = $1;
+            my $version = $2;
+            my $selector = $3 // $EMPTY;
+
+            push(@syntax_errors, $position)
+              unless length $current_soname;
+
+            $symbols_by_soname{$current_soname} //= [];
+            push(@{$symbols_by_soname{$current_soname}}, $symbol);
+
+            if ($version eq $package_version && $package_version =~ m{-}) {
+                $full_version_symbols_by_soname{$current_soname} //= [];
+                push(
+                    @{$full_version_symbols_by_soname{$current_soname}},
+                    $symbol
+                );
+
+            } elsif ($version =~ m{-}
+                && $version !~ m{~$}
+                && $version ne $package_version_wo_rev) {
+
+                $debian_revision_symbols_by_soname{$current_soname} //= [];
+                push(
+                    @{$debian_revision_symbols_by_soname{$current_soname}},
+                    $symbol
+                );
+            }
+
+            $self->pointed_hint('invalid-template-id-in-symbols-file',
+                $symbols_file->pointer($position),$selector)
+              if length $selector
+              && ($selector !~ m{^ \d+ $}x || $selector > $template_count);
+
+            next;
+        }
+
+        push(@syntax_errors, $position);
+
+    } continue {
+        ++$position;
+    }
+
+    my @duplicate_sonames
+      = grep { @{$self->symbols_positions_by_soname->{$_}} > 1 }
+      keys %{$self->symbols_positions_by_soname};
+
+    for my $soname (@duplicate_sonames) {
+
+        my $indicator
+          = $LEFT_PARENTHESIS . 'lines'
+          . $SPACE
+          . join($SPACE,
+            sort { $a <=> $b }@{$self->symbols_positions_by_soname->{$soname}})
+          . $RIGHT_PARENTHESIS;
+
+        my $pretty_soname = human_soname($soname);
+
+        $self->pointed_hint('duplicate-entry-in-symbols-control-file',
+            $symbols_file->pointer,$indicator,$pretty_soname);
+    }
+
+    $self->pointed_hint('syntax-error-in-symbols-file',
+        $symbols_file->pointer($_))
+      for uniq @syntax_errors;
+
+    # Check that all of the packages listed as dependencies in the symbols
+    # file are satisfied by the current package or its Provides.
+    # Normally, packages should only declare dependencies in their symbols
+    # files that they themselves can satisfy.
+    my $provides = $self->processable->name;
+    $provides
+      .= $LEFT_PARENTHESIS
+      . $EQUALS
+      . $SPACE
+      . $fields->value('Version')
+      . $RIGHT_PARENTHESIS
+      if $fields->declares('Version');
+
+    $provides
+      = $self->processable->relation('Provides')->logical_and($provides);
+
+    for my $soname (uniq @sonames) {
+
+        my @used_meta_labels
+          = keys %{$positions_by_soname_and_meta_label{$soname} // {} };
+
+        my $meta_lc
+          = List::Compare->new(\@used_meta_labels, \@known_meta_labels);
+
+        for my $meta_label ($meta_lc->get_Lonly) {
+
+            $self->pointed_hint(
+                'unknown-meta-field-in-symbols-file',
+                $symbols_file->pointer($_),
+                $meta_label, "($soname)"
+              )
+              for @{$positions_by_soname_and_meta_label{$soname}{$meta_label}};
+        }
+
+        $self->pointed_hint('symbols-file-missing-build-depends-package-field',
+            $symbols_file->pointer,$soname)
+          if none { $_ eq 'Build-Depends-Package' } @used_meta_labels;
+
+        my @full_version_symbols
+          = @{$full_version_symbols_by_soname{$soname} // [] };
+        if (@full_version_symbols) {
+
+            my @sorted = sort +uniq @full_version_symbols;
+
+            my $context = 'on symbol ' . $sorted[0];
+            $context .= ' and ' . (scalar @sorted - 1) . ' others'
+              if @sorted > 1;
+
+            $self->pointed_hint(
+                'symbols-file-contains-current-version-with-debian-revision',
+                $symbols_file->pointer,$context, "($soname)");
+        }
+
+        my @debian_revision_symbols
+          = @{$debian_revision_symbols_by_soname{$soname} // [] };
+        if (@debian_revision_symbols) {
+
+            my @sorted = sort +uniq @debian_revision_symbols;
+
+            my $context = 'on symbol ' . $sorted[0];
+            $context .= ' and ' . (scalar @sorted - 1) . ' others'
+              if @sorted > 1;
+
+            $self->pointed_hint('symbols-file-contains-debian-revision',
+                $symbols_file->pointer,$context, "($soname)");
+        }
+
+        # Deduplicate the list of dependencies before warning so that we don't
+        # duplicate warnings.
+        for
+          my $prerequisite (uniq @{$prerequisites_by_soname{$soname} // [] }) {
+
+            $prerequisite =~ s/ [ ] [#] MINVER [#] $//x;
+            $self->pointed_hint('symbols-declares-dependency-on-other-package',
+                $symbols_file->pointer,$prerequisite, "($soname)")
+              unless $provides->satisfies($prerequisite);
+        }
+    }
+
+    my @used_pretty_sonames;
+    for my $filename (@shared_libraries) {
+
+        my $soname = $self->soname_by_filename->{$filename};
+        my $pretty_soname = human_soname($soname);
+
+        push(@used_pretty_sonames, $pretty_soname);
+        push(@used_pretty_sonames, "udeb: $pretty_soname");
+
+        # only public shared libraries
+        $self->pointed_hint('shared-library-symbols-not-tracked',
+            $symbols_file->pointer,$pretty_soname,'for', $filename)
+          if (any { (dirname($filename) . $SLASH) eq $_ }@ldconfig_folders)
+          && !@{$self->symbols_positions_by_soname->{$soname}// [] }
+          && !is_nss_plugin($filename);
+    }
+
+    my @available_pretty_sonames
+      = map { human_soname($_) } keys %{$self->symbols_positions_by_soname};
+
+    my $unused_lc
+      = List::Compare->new(\@available_pretty_sonames,\@used_pretty_sonames);
+
+    $self->pointed_hint('surplus-shared-library-symbols',
+        $symbols_file->pointer, $_)
+      for $unused_lc->get_Lonly;
+
+    return;
+}
+
+# Extract the library name and the version from an SONAME and return them
+# separated by a space.  This code should match the split_soname function in
+# dpkg-shlibdeps.
+sub human_soname {
+    my ($string) = @_;
+
+    # libfoo.so.X.X
+    # libfoo-X.X.so
+    if (   $string =~ m{^ (.*) [.]so[.] (.*) $}x
+        || $string =~ m{^ (.*) - (\d.*) [.]so $}x) {
+
+        my $name = $1;
+        my $version = $2;
+
+        return $name . $SPACE . $version;
+    }
+
+    return $string;
+}
+
+# Returns a truth value if the first argument appears to be the path
+# to a libc nss plugin (libnss_<name>.so.$version).
+sub is_nss_plugin {
+    my ($name) = @_;
+
+    return 1
+      if $name =~ m{^ (?:.*/)? libnss_[^.]+ [.]so[.] \d+ $}x;
+
+    return 0;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Source/IncludeBinaries.pm b/lib/Lintian/Check/Debian/Source/IncludeBinaries.pm
new file mode 100644
index 0000000..48e8926
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Source/IncludeBinaries.pm
@@ -0,0 +1,77 @@
+# debian/source/include-binaries -- lintian check script -*- perl -*-
+
+# Copyright (C) 2019 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Source::IncludeBinaries;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Path::Tiny;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $sourcedir= $self->processable->patched->resolve_path('debian/source/');
+    return
+      unless $sourcedir;
+
+    my $item = $sourcedir->child('include-binaries');
+    return
+      unless $item && $item->is_open_ok;
+
+    my @lines = path($item->unpacked_path)->lines({ chomp => 1 });
+
+    # format described in dpkg-source (1)
+    my $position = 1;
+    for my $line (@lines) {
+
+        next
+          if $line =~ /^\s*$/;
+
+        next
+          if $line =~ /^#/;
+
+        # trim both ends
+        $line =~ s/^\s+|\s+$//g;
+
+        $self->pointed_hint('unused-entry-in-debian-source-include-binaries',
+            $item->pointer($position), $line)
+          unless $self->processable->patched->resolve_path($line);
+
+    } continue {
+        ++$position;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/SourceDir.pm b/lib/Lintian/Check/Debian/SourceDir.pm
new file mode 100644
index 0000000..2fd2ebf
--- /dev/null
+++ b/lib/Lintian/Check/Debian/SourceDir.pm
@@ -0,0 +1,170 @@
+# debian/source directory content -- lintian check script -*- perl -*-
+
+# Copyright (C) 2010 by Raphael Hertzog
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::SourceDir;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+
+our %KNOWN_FORMATS = map { $_ => 1 }
+  ('1.0', '2.0', '3.0 (quilt)', '3.0 (native)', '3.0 (git)', '3.0 (bzr)');
+
+my %OLDER_FORMATS = map { $_ => 1 }('1.0');
+
+sub source {
+    my ($self) = @_;
+
+    my $processable = $self->processable;
+
+    my $dsrc = $processable->patched->resolve_path('debian/source/');
+    my ($format_file, $git_pfile, $format, $format_extra);
+
+    $format_file = $dsrc->child('format') if $dsrc;
+
+    if ($format_file and $format_file->is_open_ok) {
+
+        open(my $fd, '<', $format_file->unpacked_path)
+          or die encode_utf8('Cannot open ' . $format_file->unpacked_path);
+
+        $format = <$fd>;
+        chomp $format;
+        close($fd);
+        $format_extra = $EMPTY;
+        die encode_utf8("unknown source format $format")
+          unless $KNOWN_FORMATS{$format};
+    } else {
+        $self->hint('missing-debian-source-format');
+        $format = '1.0';
+        $format_extra = 'implicit';
+    }
+    if ($format eq '1.0') {
+        $format_extra .= $SPACE if $format_extra;
+        if (keys %{$processable->diffstat}) {
+            $format_extra .= 'non-native';
+        } else {
+            $format_extra .= 'native';
+        }
+    }
+    my $format_info = $format;
+    $format_info .= " [$format_extra]"
+      if $format_extra;
+    $self->hint('source-format', $format_info);
+
+    $self->hint('older-source-format', $format) if $OLDER_FORMATS{$format};
+
+    return if not $dsrc;
+
+    $git_pfile = $dsrc->child('git-patches');
+
+    if ($git_pfile and $git_pfile->is_open_ok and $git_pfile->size != 0) {
+
+        open(my $git_patches_fd, '<', $git_pfile->unpacked_path)
+          or die encode_utf8('Cannot open ' . $git_pfile->unpacked_path);
+
+        if (any { !/^\s*+#|^\s*+$/} <$git_patches_fd>) {
+            my $dpseries
+              = $processable->patched->resolve_path('debian/patches/series');
+            # gitpkg does not create series as a link, so this is most likely
+            # a traversal attempt.
+            if (not $dpseries or not $dpseries->is_open_ok) {
+
+                $self->pointed_hint('git-patches-not-exported',
+                    $git_pfile->pointer);
+
+            } else {
+                open(my $series_fd, '<', $dpseries->unpacked_path)
+                  or
+                  die encode_utf8('Cannot open ' . $dpseries->unpacked_path);
+
+                my $comment_line = <$series_fd>;
+                my $count = grep { !/^\s*+\#|^\s*+$/ } <$series_fd>;
+
+                $self->pointed_hint('git-patches-not-exported',
+                    $dpseries->pointer)
+                  unless (
+                    $count
+                    && ($comment_line
+                        =~ /^\s*\#.*quilt-patches-deb-export-hook/)
+                  );
+
+                close $series_fd;
+            }
+        }
+        close $git_patches_fd;
+    }
+
+    my $KNOWN_FILES= $self->data->load('debian-source-dir/known-files');
+
+    my @files = grep { !$_->is_dir } $dsrc->children;
+    for my $item (@files) {
+
+        $self->pointed_hint('unknown-file-in-debian-source', $item->pointer)
+          unless $KNOWN_FILES->recognizes($item->basename);
+    }
+
+    my $options = $processable->patched->resolve_path('debian/source/options');
+    if ($options and $options->is_open_ok) {
+
+        open(my $fd, '<', $options->unpacked_path)
+          or die encode_utf8('Cannot open ' . $options->unpacked_path);
+
+        my $position = 1;
+        while (my $line = <$fd>) {
+
+            if ($line =~ /^\s*(compression(?:-level)?\s*=\s+\S+)\n/) {
+
+                my $level = $1;
+
+                $self->pointed_hint(
+                    'custom-compression-in-debian-source-options',
+                    $options->pointer($position), $level);
+            }
+
+        } continue {
+            ++$position;
+        }
+
+        close $fd;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Substvars.pm b/lib/Lintian/Check/Debian/Substvars.pm
new file mode 100644
index 0000000..d612783
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Substvars.pm
@@ -0,0 +1,55 @@
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Substvars;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    $self->pointed_hint('source-contains-debian-substvars', $item->pointer)
+      if $item->name =~ m{^debian/(?:.+\.)?substvars$}s;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Symbols.pm b/lib/Lintian/Check/Debian/Symbols.pm
new file mode 100644
index 0000000..42b36fe
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Symbols.pm
@@ -0,0 +1,83 @@
+# debian/symbols -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2019-2021 Felix Lechner
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Symbols;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    # look at symbols files
+    return
+      unless $item->name =~ qr{^ debian/ (?:.+[.]) symbols $}x;
+
+    return
+      unless $item->is_file && $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        chop $line;
+        next
+          if $line =~ /^\s*$/
+          || $line =~ /^#/;
+
+        # meta-information
+        if ($line =~ /^\*\s(\S+):\s+(\S+)/) {
+
+            my $field = $1;
+            my $value = $2;
+
+            $self->pointed_hint('package-placeholder-in-symbols-file',
+                $item->pointer($position))
+              if $field eq 'Build-Depends-Package' && $value =~ /#PACKAGE#/;
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/TrailingWhitespace.pm b/lib/Lintian/Check/Debian/TrailingWhitespace.pm
new file mode 100644
index 0000000..465fa59
--- /dev/null
+++ b/lib/Lintian/Check/Debian/TrailingWhitespace.pm
@@ -0,0 +1,105 @@
+# debian/trailing-whitespace -- lintian check script -*- perl -*-
+#
+# based on debhelper check,
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::TrailingWhitespace;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $KEEP_EMPTY_FIELDS => -1;
+const my $LAST_ITEM => -1;
+
+# list of files to check for a trailing whitespace characters
+my %PROHIBITED_TRAILS = (
+    'debian/changelog'        => qr{\s+$},
+    'debian/control'          => qr{\s+$},
+    # allow trailing tabs in make
+    'debian/rules'            => qr{[ ]+$},
+);
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless exists $PROHIBITED_TRAILS{$item->name};
+
+    return
+      unless $item->is_valid_utf8;
+
+    my $contents = $item->decoded_utf8;
+    my @lines = split(/\n/, $contents, $KEEP_EMPTY_FIELDS);
+
+    my @trailing_whitespace;
+    my @empty_at_end;
+
+    my $position = 1;
+    for my $line (@lines) {
+
+        push(@trailing_whitespace, $position)
+          if $line =~ $PROHIBITED_TRAILS{$item->name};
+
+        # keeps track of any empty lines at the end
+        if (length $line) {
+            @empty_at_end = ();
+        } else {
+            push(@empty_at_end, $position);
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    # require a newline at end and remove it
+    if (scalar @empty_at_end && $empty_at_end[$LAST_ITEM] == scalar @lines){
+        pop @empty_at_end;
+    } else {
+        $self->pointed_hint('no-newline-at-end', $item->pointer);
+    }
+
+    push(@trailing_whitespace, @empty_at_end);
+
+    $self->pointed_hint('trailing-whitespace', $item->pointer($_))
+      for @trailing_whitespace;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Upstream/Metadata.pm b/lib/Lintian/Check/Debian/Upstream/Metadata.pm
new file mode 100644
index 0000000..410733a
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Upstream/Metadata.pm
@@ -0,0 +1,191 @@
+# debian/upstream/metadata -- lintian check script -*- perl -*-
+
+# Copyright (C) 2016 Petter Reinholdtsen
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Jelmer Vernooij
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Upstream::Metadata;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::Compare;
+use List::Util qw(none);
+use Syntax::Keyword::Try;
+use YAML::XS;
+
+# default changed to false in 0.81; enable then in .perlcriticrc
+$YAML::XS::LoadBlessed = 0;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+# Need 0.69 for $LoadBlessed (#861958)
+const my $HAS_LOAD_BLESSED => 0.69;
+
+# taken from https://wiki.debian.org/UpstreamMetadata
+my @known_fields = qw(
+  Archive
+  ASCL-Id
+  Bug-Database
+  Bug-Submit
+  Cite-As
+  Changelog
+  CPE
+  Documentation
+  Donation
+  FAQ
+  Funding
+  Gallery
+  Other-References
+  Reference
+  Registration
+  Registry
+  Repository
+  Repository-Browse
+  Screenshots
+  Security-Contact
+  Webservice
+);
+
+# tolerated for packages not using DEP-5 copyright
+my @tolerated_fields = qw(
+  Name
+  Contact
+);
+
+sub source {
+    my ($self) = @_;
+
+    my $item
+      = $self->processable->patched->resolve_path('debian/upstream/metadata');
+
+    if ($self->processable->native) {
+
+        $self->pointed_hint('upstream-metadata-in-native-source',
+            $item->pointer)
+          if defined $item;
+        return;
+    }
+
+    unless (defined $item) {
+        $self->hint('upstream-metadata-file-is-missing');
+        return;
+    }
+
+    $self->pointed_hint('upstream-metadata-exists', $item->pointer);
+
+    unless ($item->is_open_ok) {
+        $self->pointed_hint('upstream-metadata-is-not-a-file', $item->pointer);
+        return;
+    }
+
+    return
+      if $YAML::XS::VERSION < $HAS_LOAD_BLESSED;
+
+    my $yaml;
+    try {
+        $yaml = YAML::XS::LoadFile($item->unpacked_path);
+
+        die
+          unless defined $yaml;
+
+    } catch {
+
+        my $message = $@;
+        my ($reason, $document, $line, $column)= (
+            $message =~ m{
+                \AYAML::XS::Load\sError:\sThe\sproblem:\n
+                \n\s++(.+)\n
+                \n
+                was\sfound\sat\sdocument:\s(\d+),\sline:\s(\d+),\scolumn:\s(\d+)\n}x
+        );
+
+        $message
+          = "$reason (at document $document, line $line, column $column)"
+          if ( length $reason
+            && length $document
+            && length $line
+            && length $document);
+
+        $self->pointed_hint('upstream-metadata-yaml-invalid',
+            $item->pointer, $message);
+
+        return;
+    }
+
+    unless (ref $yaml eq 'HASH') {
+
+        $self->pointed_hint('upstream-metadata-not-yaml-mapping',
+            $item->pointer);
+        return;
+    }
+
+    for my $field (keys %{$yaml}) {
+
+        $self->pointed_hint('upstream-metadata', $item->pointer, $field,
+            $yaml->{$field})
+          if ref($yaml->{$field}) eq $EMPTY;
+    }
+
+    my $lc
+      = List::Compare->new([keys %{$yaml}],[@known_fields, @tolerated_fields]);
+    my @invalid_fields = $lc->get_Lonly;
+
+    $self->pointed_hint('upstream-metadata-field-unknown', $item->pointer, $_)
+      for @invalid_fields;
+
+    $self->pointed_hint('upstream-metadata-missing-repository', $item->pointer)
+      if none { defined $yaml->{$_} } qw(Repository Repository-Browse);
+
+    $self->pointed_hint('upstream-metadata-missing-bug-tracking',
+        $item->pointer)
+      if none { defined $yaml->{$_} } qw(Bug-Database Bug-Submit);
+
+    return;
+}
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # here we check old upstream specification
+    # debian/upstream should be a directory
+    $self->pointed_hint('debian-upstream-obsolete-path', $item->pointer)
+      if $item->name eq 'debian/upstream'
+      || $item->name eq 'debian/upstream-metadata.yaml';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Upstream/SigningKey.pm b/lib/Lintian/Check/Debian/Upstream/SigningKey.pm
new file mode 100644
index 0000000..686966c
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Upstream/SigningKey.pm
@@ -0,0 +1,173 @@
+# debian/upstream/signing-key -- lintian check script -*- perl -*-
+
+# Copyright (C) 2018 Felix Lechner
+#
+# This program is free software.  It is distributed under the terms of
+# the GNU General Public License as published by the Free Software
+# Foundation; either version 2 of the License, or (at your option) any
+# later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Upstream::SigningKey;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use File::Temp;
+use List::Util qw(pairs);
+use Unicode::UTF8 qw(decode_utf8);
+
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $SIGNING_KEY_FILENAMES
+      = $self->data->load('common/signing-key-filenames');
+
+    # Check all possible locations for signing keys
+    my %key_items;
+    for my $key_name ($SIGNING_KEY_FILENAMES->all) {
+        my $item
+          = $self->processable->patched->resolve_path("debian/$key_name");
+        $key_items{$key_name} = $item
+          if $item && $item->is_file;
+    }
+
+    # Check if more than one signing key is present
+    $self->hint('public-upstream-keys-in-multiple-locations',
+        (sort keys %key_items))
+      if scalar keys %key_items > 1;
+
+    # Go through signing keys and run checks for each
+    for my $key_name (sort keys %key_items) {
+
+        # native packages should not have such keys
+        if ($self->processable->native) {
+
+            $self->pointed_hint('public-upstream-key-in-native-package',
+                $key_items{$key_name}->pointer);
+            next;
+        }
+
+        # set up a temporary directory for gpg
+        my $tempdir = File::Temp->newdir();
+
+        # get keys packets from gpg
+        my @command = (
+            'gpg', '--homedir',
+            $tempdir, '--batch',
+            '--attribute-fd', '1',
+            '--status-fd', '2',
+            '--with-colons', '--list-packets',
+            $key_items{$key_name}->unpacked_path
+        );
+        my $bytes = safe_qx(@command);
+
+        if ($?) {
+            $self->pointed_hint(
+                'public-upstream-key-unusable',
+                $key_items{$key_name}->pointer,
+                'cannot be processed'
+            );
+            next;
+        }
+
+        my $output = decode_utf8($bytes);
+
+        # remove comments
+        $output =~ s/^#[^\n]*$//mg;
+
+        # split into separate keys
+        my @keys = split(/^:public key packet:.*$/m, $output);
+
+        # discard leading information
+        shift @keys;
+
+        unless (scalar @keys) {
+            $self->pointed_hint(
+                'public-upstream-key-unusable',
+                $key_items{$key_name}->pointer,
+                'contains no keys'
+            );
+            next;
+        }
+
+        for my $key (@keys) {
+
+            # parse each key into separate packets
+            my ($public_key, @pieces) = split(/^(:.+)$/m, $key);
+            my @packets = pairs @pieces;
+
+            # require at least one packet
+            unless (length $public_key) {
+                $self->pointed_hint(
+                    'public-upstream-key-unusable',
+                    $key_items{$key_name}->pointer,
+                    'has no public key'
+                );
+                next;
+            }
+
+            # look for key identifier
+            unless ($public_key =~ qr/^\s*keyid:\s+(\S+)$/m) {
+                $self->pointed_hint(
+                    'public-upstream-key-unusable',
+                    $key_items{$key_name}->pointer,
+                    'has no keyid'
+                );
+                next;
+            }
+            my $keyid = $1;
+
+            # look for third-party signatures
+            my @thirdparty;
+            for my $packet (@packets) {
+
+                my $header = $packet->[0];
+                if ($header =~ qr/^:signature packet: algo \d+, keyid (\S*)$/){
+
+                    my $signatory = $1;
+                    push(@thirdparty, $signatory)
+                      unless $signatory eq $keyid;
+                }
+            }
+
+            # signatures by parties other than self
+            my $extrasignatures = scalar @thirdparty;
+
+            # export-minimal strips such signatures
+            $self->pointed_hint(
+                'public-upstream-key-not-minimal',
+                $key_items{$key_name}->pointer,
+                "has $extrasignatures extra signature(s) for keyid $keyid"
+            )if $extrasignatures;
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Variables.pm b/lib/Lintian/Check/Debian/Variables.pm
new file mode 100644
index 0000000..31fa9a4
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Variables.pm
@@ -0,0 +1,60 @@
+# debian/variables -- lintian check script -*- perl -*-
+
+# Copyright (C) 2006 Russ Allbery <rra@debian.org>
+# Copyright (C) 2005 Rene van Bevern <rvb@pro-linux.de>
+# Copyright (C) 2019-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+package Lintian::Check::Debian::Variables;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(none);
+
+const my @WANTED_FILES => (qr{ (.+ [.])? install }sx, qr{ (.+ [.])? links }sx);
+
+const my @ILLEGAL_VARIABLES => qw(DEB_BUILD_MULTIARCH);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->name =~ m{^ debian/ }sx;
+
+    return
+      if none { $item->name =~ m{ / $_ $}sx } @WANTED_FILES;
+
+    for my $variable (@ILLEGAL_VARIABLES) {
+
+        $self->pointed_hint('illegal-variable', $item->pointer, $variable)
+          if $item->decoded_utf8 =~ m{ \b $variable \b }msx;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/VersionSubstvars.pm b/lib/Lintian/Check/Debian/VersionSubstvars.pm
new file mode 100644
index 0000000..e3789b8
--- /dev/null
+++ b/lib/Lintian/Check/Debian/VersionSubstvars.pm
@@ -0,0 +1,206 @@
+# debian/version-substvars -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2006 Adeodato Simo
+# Copyright (C) 2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+# SUMMARY
+# =======
+#
+# What breaks
+# -----------
+#
+# (b1) any -> any (= ${source:Version})          -> use b:V
+# (b2) any -> all (= ${binary:Version}) [or S-V] -> use s:V
+# (b3) all -> any (= ${either-of-them})          -> use (>= ${s:V}),
+#                                                   optionally (<< ${s:V}.1~)
+#
+# Note (b2) also breaks if (>= ${binary:Version}) [or S-V] is used.
+#
+# Always warn on ${Source-Version} even if it doesn't break since the substvar
+# is now considered deprecated.
+
+package Lintian::Check::Debian::VersionSubstvars;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any uniq);
+
+use Lintian::Relation;
+use Lintian::Util qw($PKGNAME_REGEX);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $EQUAL => q{=};
+
+sub source {
+    my ($self) = @_;
+
+    my $debian_control = $self->processable->debian_control;
+
+    my @provides;
+    push(@provides,
+        $debian_control->installable_fields($_)
+          ->trimmed_list('Provides', qr/\s*,\s*/))
+      for $debian_control->installables;
+
+    for my $installable ($debian_control->installables) {
+
+        my $installable_control
+          = $debian_control->installable_fields($installable);
+
+        for my $field (
+            qw(Depends Pre-Depends Recommends Suggests Conflicts Replaces)) {
+
+            next
+              unless $installable_control->declares($field);
+
+            my $position = $installable_control->position($field);
+
+            my $relation
+              = $self->processable->binary_relation($installable, $field);
+
+            $self->pointed_hint(
+                'substvar-source-version-is-deprecated',
+                $debian_control->item->pointer($position),
+                $installable, $field
+            )if $relation->matches(qr/\$[{]Source-Version[}]/);
+
+            my %external;
+            my $visitor = sub {
+                my ($value) = @_;
+
+                if (
+                    $value
+                    =~m{^($PKGNAME_REGEX)(?: :[-a-z0-9]+)? \s*   # pkg-name $1
+                       \(\s*[\>\<]?[=\>\<]\s*                  # REL 
+                        (\$[{](?:source:|binary:)(?:Upstream-)?Version[}]) # {subvar}
+                     }x
+                ) {
+                    my $other = $1;
+                    my $substvar = $2;
+
+                    $external{$substvar} //= [];
+                    push(@{ $external{$substvar} }, $other);
+                }
+            };
+            $relation->visit($visitor, Lintian::Relation::VISIT_PRED_FULL);
+
+            for my $substvar (keys %external) {
+                for my $other (uniq @{ $external{$substvar} }) {
+
+                    # We can't test dependencies on packages whose names are
+                    # formed via substvars expanded during the build.  Assume
+                    # those maintainers know what they're doing.
+                    $self->pointed_hint(
+                        'version-substvar-for-external-package',
+                        $debian_control->item->pointer($position),
+                        $field,
+                        $substvar,
+                        "$installable -> $other"
+                      )
+                      unless $debian_control->installable_fields($other)
+                      ->declares('Architecture')
+                      || (any { "$other (= $substvar)" eq $_ } @provides)
+                      || $other =~ /\$\{\S+\}/;
+                }
+            }
+        }
+
+        my @pre_depends
+          = $installable_control->trimmed_list('Pre-Depends', qr/\s*,\s*/);
+        my @depends
+          = $installable_control->trimmed_list('Depends', qr/\s*,\s*/);
+
+        for my $versioned (uniq(@pre_depends, @depends)) {
+
+            next
+              unless $versioned
+              =~m{($PKGNAME_REGEX)(?: :any)? \s*               # pkg-name
+                       \(\s*([>]?=)\s*                               # rel
+                       \$[{]((?:Source-|source:|binary:)Version)[}] # subvar
+                      }x;
+
+            my $prerequisite = $1;
+            my $operator = $2;
+            my $substvar = $3;
+
+            my $prerequisite_control
+              = $debian_control->installable_fields($prerequisite);
+
+            # external relation or subst var package; handled above
+            next
+              unless $prerequisite_control->declares('Architecture');
+
+            my $prerequisite_is_all
+              = ($prerequisite_control->value('Architecture') eq 'all');
+            my $installable_is_all
+              = ($installable_control->value('Architecture') eq 'all');
+
+            my $context = "$installable -> $prerequisite";
+
+            # (b1) any -> any (= ${source:Version})
+            $self->hint('not-binnmuable-any-depends-any', $context)
+              if !$installable_is_all
+              && !$prerequisite_is_all
+              && $operator eq $EQUAL
+              && $substvar eq 'source:Version';
+
+            # (b2) any -> all (= ${binary:Version}) [or S-V]
+            $self->hint('maybe-not-arch-all-binnmuable', $context)
+              if !$installable_is_all
+              && $prerequisite_is_all
+              && $operator eq $EQUAL
+              && $substvar eq 'source:Version';
+
+            # (b2) any -> all (* ${binary:Version}) [or S-V]
+            $self->hint('not-binnmuable-any-depends-all', $context)
+              if !$installable_is_all
+              && $prerequisite_is_all
+              && $substvar ne 'source:Version';
+
+            # (b3) all -> any (= ${either-of-them})
+            $self->hint('not-binnmuable-all-depends-any', $context)
+              if $installable_is_all
+              && !$prerequisite_is_all
+              && $operator eq $EQUAL;
+
+            # any -> any (>= ${source:Version})
+            # technically this can be "binNMU'ed", though it is
+            # a bit weird.
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Watch.pm b/lib/Lintian/Check/Debian/Watch.pm
new file mode 100644
index 0000000..2f891d3
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Watch.pm
@@ -0,0 +1,379 @@
+# debian/watch -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2008 Patrick Schoenfeld
+# Copyright (C) 2008 Russ Allbery
+# Copyright (C) 2008 Raphael Geissert
+# Copyright (C) 2019 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Watch;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any firstval firstres);
+use Path::Tiny;
+
+use Lintian::Util qw($PKGREPACK_REGEX);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+
+const my $URL_ACTION_FIELDS => 4;
+const my $VERSION_ACTION_FIELDS => 3;
+
+const my $DMANGLES_AUTOMATICALLY => 4;
+
+sub source {
+    my ($self) = @_;
+
+    my $item = $self->processable->patched->resolve_path('debian/watch');
+    unless ($item && $item->is_file) {
+
+        $self->hint('debian-watch-file-is-missing')
+          unless $self->processable->native;
+
+        return;
+    }
+
+    # Perform the other checks even if it is a native package
+    $self->pointed_hint('debian-watch-file-in-native-package', $item->pointer)
+      if $self->processable->native;
+
+    # Check if the Debian version contains anything that resembles a repackaged
+    # source package sign, for fine grained version mangling check
+    # If the version field is missing, we assume a neutral non-native one.
+
+    # upstream method returns empty for native packages
+    my $upstream = $self->processable->changelog_version->upstream;
+    my ($prerelease) = ($upstream =~ qr/(alpha|beta|rc)/i);
+
+# there is a good repack indicator in $processable->repacked but we need the text
+    my ($repack) = ($upstream =~ $PKGREPACK_REGEX);
+
+    return
+      unless $item->is_open_ok;
+
+    my $contents = $item->bytes;
+
+    # each pattern marks a multi-line (!) selection for the tag message
+    my @templatepatterns
+      = (qr/^\s*#\s*(Example watch control file for uscan)/mi,qr/(<project>)/);
+    my $templatestring;
+
+    for my $pattern (@templatepatterns) {
+        ($templatestring) = ($contents =~ $pattern);
+        last if defined $templatestring;
+    }
+
+    $self->pointed_hint('debian-watch-contains-dh_make-template',
+        $item->pointer, $templatestring)
+      if length $templatestring;
+
+    # remove backslash at end; uscan will catch it
+    $contents =~ s/(?<!\\)\\$//;
+
+    my $standard;
+
+    my @lines = split(/\n/, $contents);
+
+    # look for watch file version
+    for my $line (@lines) {
+
+        if ($line =~ /^\s*version\s*=\s*(\d+)\s*$/) {
+            if (length $1) {
+                $standard = $1;
+                last;
+            }
+        }
+    }
+
+    return
+      unless defined $standard;
+
+    # version 1 too broken to check
+    return
+      if $standard < 2;
+
+    # allow spaces for all watch file versions (#950250, #950277)
+    my $separator = qr/\s*,\s*/;
+
+    my $withpgpverification = 0;
+    my %dversions;
+
+    my $position = 1;
+    my $continued = $EMPTY;
+    for my $line (@lines) {
+
+        my $pointer = $item->pointer($position);
+
+        # strip leading spaces
+        $line =~ s/^\s*//;
+
+        # strip comments, if any
+        $line =~ s/^\#.*$//;
+
+        unless (length $line) {
+            $continued = $EMPTY;
+            next;
+        }
+
+        # merge continuation lines
+        if ($line =~ s/\\$//) {
+            $continued .= $line;
+            next;
+        }
+
+        $line = $continued . $line
+          if length $continued;
+
+        $continued = $EMPTY;
+
+        next
+          if $line =~ /^version\s*=\s*\d+\s*$/;
+
+        my $remainder = $line;
+
+        my @options;
+
+        # keep order; otherwise. alternative \S+ ends up with quotes
+        if ($remainder =~ s/opt(?:ion)?s=(?|\"((?:[^\"]|\\\")+)\"|(\S+))\s+//){
+            @options = split($separator, $1);
+        }
+
+        unless (length $remainder) {
+
+            $self->pointed_hint('debian-watch-line-invalid', $pointer, $line);
+            next;
+        }
+
+        my $repack_mangle = 0;
+        my $repack_dmangle = 0;
+        my $repack_dmangle_auto = 0;
+        my $prerelease_mangle = 0;
+        my $prerelease_umangle = 0;
+
+        for my $option (@options) {
+
+            if (length $repack) {
+                $repack_mangle = 1
+                  if $option
+                  =~ /^[ud]?versionmangle\s*=\s*(?:auto|.*$repack.*)/;
+                $repack_dmangle = 1
+                  if $option =~ /^dversionmangle\s*=\s*(?:auto|.*$repack.*)/;
+            }
+
+            if (length $prerelease) {
+                $prerelease_mangle = 1
+                  if $option =~ /^[ud]?versionmangle\s*=.*$prerelease/;
+                $prerelease_umangle = 1
+                  if $option =~ /^uversionmangle\s*=.*$prerelease/;
+            }
+
+            $repack_dmangle_auto = 1
+              if $option =~ /^dversionmangle\s*=.*(?:s\/\@DEB_EXT\@\/|auto)/
+              && $standard >= $DMANGLES_AUTOMATICALLY;
+
+            $withpgpverification = 1
+              if $option =~ /^pgpsigurlmangle\s*=\s*/
+              || $option =~ /^pgpmode\s*=\s*(?!none\s*$)\S.*$/;
+
+            my ($name, $value) = split(m{ \s* = \s* }x, $option, 2);
+
+            next
+              unless length $name;
+
+            $value //= $EMPTY;
+
+            $self->pointed_hint('prefer-uscan-symlink',$pointer, $name, $value)
+              if $name eq 'filenamemangle';
+        }
+
+        $self->pointed_hint(
+            'debian-watch-file-uses-deprecated-sf-redirector-method',
+            $pointer,$remainder)
+          if $remainder =~ m{qa\.debian\.org/watch/sf\.php\?};
+
+        $self->pointed_hint('debian-watch-file-uses-deprecated-githubredir',
+            $pointer, $remainder)
+          if $remainder =~ m{githubredir\.debian\.net};
+
+        $self->pointed_hint('debian-watch-lacks-sourceforge-redirector',
+            $pointer, $remainder)
+          if $remainder =~ m{ (?:https?|ftp)://
+                              (?:(?:.+\.)?dl|(?:pr)?downloads?|ftp\d?|upload) \.
+                              (?:sourceforge|sf)\.net}xsm
+          || $remainder =~ m{https?://(?:www\.)?(?:sourceforge|sf)\.net
+                                                   /project/showfiles\.php}xsm
+          || $remainder =~ m{https?://(?:www\.)?(?:sourceforge|sf)\.net
+                  /projects/.+/files}xsm;
+
+        if ($remainder =~ m{((?:http|ftp):(?!//sf.net/)\S+)}) {
+            $self->pointed_hint('debian-watch-uses-insecure-uri', $pointer,$1);
+        }
+
+        # This bit is as-is from uscan.pl:
+        my ($base, $filepattern, $lastversion, $action)
+          = split($SPACE, $remainder, $URL_ACTION_FIELDS);
+
+        # Per #765995, $base might be undefined.
+        if (defined $base) {
+            if ($base =~ s{/([^/]*\([^/]*\)[^/]*)$}{/}) {
+               # Last component of $base has a pair of parentheses, so no
+               # separate filepattern field; we remove the filepattern from the
+               # end of $base and rescan the rest of the line
+                $filepattern = $1;
+                (undef, $lastversion, $action)
+                  = split($SPACE, $remainder, $VERSION_ACTION_FIELDS);
+            }
+
+            $dversions{$lastversion} = 1
+              if defined $lastversion;
+
+            $lastversion = 'debian'
+              unless defined $lastversion;
+        }
+
+        # If the version of the package contains dfsg, assume that it needs
+        # to be mangled to get reasonable matches with upstream.
+        my $needs_repack_mangling = ($repack && $lastversion eq 'debian');
+
+        $self->pointed_hint('debian-watch-not-mangling-version',
+            $pointer, $line)
+          if $needs_repack_mangling
+          && !$repack_mangle
+          && !$repack_dmangle_auto;
+
+        $self->pointed_hint('debian-watch-mangles-debian-version-improperly',
+            $pointer, $line)
+          if $needs_repack_mangling
+          && $repack_mangle
+          && !$repack_dmangle;
+
+        my $needs_prerelease_mangling
+          = ($prerelease && $lastversion eq 'debian');
+
+        $self->pointed_hint('debian-watch-mangles-upstream-version-improperly',
+            $pointer, $line)
+          if $needs_prerelease_mangling
+          && $prerelease_mangle
+          && !$prerelease_umangle;
+
+        my $upstream_url = $remainder;
+
+        # Keep only URL part
+        $upstream_url =~ s/(.*?\S)\s.*$/$1/;
+
+        for my $option (@options) {
+            if ($option =~ /^ component = (.+) $/x) {
+
+                my $component = $1;
+
+                $self->pointed_hint('debian-watch-upstream-component',
+                    $pointer, $upstream_url, $component);
+            }
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    $self->pointed_hint('debian-watch-does-not-check-openpgp-signature',
+        $item->pointer)
+      unless $withpgpverification;
+
+    my $SIGNING_KEY_FILENAMES
+      = $self->data->load('common/signing-key-filenames');
+
+    # look for upstream signing key
+    my @candidates
+      = map { $self->processable->patched->resolve_path("debian/$_") }
+      $SIGNING_KEY_FILENAMES->all;
+    my $keyfile = firstval {$_ && $_->is_file} @candidates;
+
+    # check upstream key is present if needed
+    $self->pointed_hint('debian-watch-file-pubkey-file-is-missing',
+        $item->pointer)
+      if $withpgpverification && !$keyfile;
+
+    # check upstream key is used if present
+    $self->pointed_hint('debian-watch-could-verify-download',
+        $item->pointer, $keyfile->name)
+      if $keyfile && !$withpgpverification;
+
+    if (defined $self->processable->changelog && %dversions) {
+
+        my %changelog_versions;
+        my $count = 1;
+        my $changelog = $self->processable->changelog;
+        for my $entry (@{$changelog->entries}) {
+            my $uversion = $entry->Version;
+            $uversion =~ s/-[^-]+$//; # revision
+            $uversion =~ s/^\d+://; # epoch
+            $changelog_versions{'orig'}{$entry->Version} = $count;
+
+            # Preserve the first value here to correctly detect old versions.
+            $changelog_versions{'mangled'}{$uversion} = $count
+              unless (exists($changelog_versions{'mangled'}{$uversion}));
+            $count++;
+        }
+
+        for my $dversion (sort keys %dversions) {
+
+            next
+              if $dversion eq 'debian';
+
+            local $" = ', ';
+
+            if (!$self->processable->native
+                && exists($changelog_versions{'orig'}{$dversion})) {
+
+                $self->pointed_hint(
+                    'debian-watch-file-specifies-wrong-upstream-version',
+                    $item->pointer, $dversion);
+                next;
+            }
+
+            if (exists $changelog_versions{'mangled'}{$dversion}
+                && $changelog_versions{'mangled'}{$dversion} != 1) {
+
+                $self->pointed_hint(
+                    'debian-watch-file-specifies-old-upstream-version',
+                    $item->pointer, $dversion);
+                next;
+            }
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debian/Watch/Standard.pm b/lib/Lintian/Check/Debian/Watch/Standard.pm
new file mode 100644
index 0000000..129966d
--- /dev/null
+++ b/lib/Lintian/Check/Debian/Watch/Standard.pm
@@ -0,0 +1,98 @@
+# debian/watch/standard -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debian::Watch::Standard;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::Compare;
+use List::Util qw(max);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SPACE => q{ };
+
+const my @STANDARDS => (2, 3, 4);
+const my $NEWLY_SUPERSEEDED => 3;
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->name eq 'debian/watch';
+
+    my $contents = $item->bytes;
+    return
+      unless length $contents;
+
+    # look for version
+    my @mentioned = ($contents =~ /^ version \s* = \s* (\d+) \s* $/gmsx);
+
+    my $has_contents = !!($contents =~ m{^ \s* [^#] }gmx);
+
+    if ($has_contents && !@mentioned) {
+
+        $self->pointed_hint('missing-debian-watch-file-standard',
+            $item->pointer);
+        return;
+    }
+
+    $self->pointed_hint('multiple-debian-watch-file-standards',
+        $item->pointer,join($SPACE, @mentioned))
+      if @mentioned > 1;
+
+    my $standard_lc = List::Compare->new(\@mentioned, \@STANDARDS);
+    my @unknown = $standard_lc->get_Lonly;
+    my @known = $standard_lc->get_intersection;
+
+    $self->pointed_hint('unknown-debian-watch-file-standard',
+        $item->pointer, $_)
+      for @unknown;
+
+    return
+      unless @known;
+
+    my $highest = max(@known);
+    $self->pointed_hint('debian-watch-file-standard', $item->pointer,$highest);
+
+    $self->pointed_hint('older-debian-watch-file-standard',
+        $item->pointer, $highest)
+      if $highest == $NEWLY_SUPERSEEDED;
+
+    $self->pointed_hint('obsolete-debian-watch-file-standard',
+        $item->pointer, $highest)
+      if $highest < $NEWLY_SUPERSEEDED;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debug/Automatic.pm b/lib/Lintian/Check/Debug/Automatic.pm
new file mode 100644
index 0000000..1bb803f
--- /dev/null
+++ b/lib/Lintian/Check/Debug/Automatic.pm
@@ -0,0 +1,63 @@
+# debug/automatic -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debug::Automatic;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+
+    for my $installable ($control->installables) {
+        my $installable_fields = $control->installable_fields($installable);
+
+        my $field = 'Package';
+
+        my $control_item= $self->processable->debian_control->item;
+        my $position = $installable_fields->position($field);
+        my $pointer = $control_item->pointer($position);
+
+        $self->pointed_hint(
+            'debian-control-has-dbgsym-package',$pointer,
+            "(in section for $installable)", $field
+        )if $installable =~ m{ [-] dbgsym $}x;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Debug/Obsolete.pm b/lib/Lintian/Check/Debug/Obsolete.pm
new file mode 100644
index 0000000..77e9bba
--- /dev/null
+++ b/lib/Lintian/Check/Debug/Obsolete.pm
@@ -0,0 +1,70 @@
+# debug/obsolete -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Debug::Obsolete;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(none);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+
+    my $KNOWN_LEGACY_DBG_PATTERNS= $self->data->load('common/dbg-pkg');
+
+    for my $installable ($control->installables) {
+        my $installable_fields = $control->installable_fields($installable);
+
+        my $field = 'Package';
+
+        my $control_item= $self->processable->debian_control->item;
+        my $position = $installable_fields->position($field);
+        my $pointer = $control_item->pointer($position);
+
+        $self->pointed_hint(
+            'debian-control-has-obsolete-dbg-package',$pointer,
+            "(in section for $installable)", $field
+          )
+          if $installable =~ m{ [-] dbg $}x
+          && (none { $installable =~ m{$_}xms }
+            $KNOWN_LEGACY_DBG_PATTERNS->all);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Desktop/Dbus.pm b/lib/Lintian/Check/Desktop/Dbus.pm
new file mode 100644
index 0000000..31d1f79
--- /dev/null
+++ b/lib/Lintian/Check/Desktop/Dbus.pm
@@ -0,0 +1,189 @@
+# desktop/dbus -- lintian check script, vaguely based on apache2 -*- perl -*-
+#
+# Copyright (C) 2012 Arno Toell
+# Copyright (C) 2014 Collabora Ltd.
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Desktop::Dbus;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::UtilsBy qw(uniq_by);
+
+const my $EMPTY => q{};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub installable {
+    my ($self) = @_;
+
+    my $index = $self->processable->installed;
+
+    my @files;
+    for my $prefix (qw(etc/dbus-1 usr/share/dbus-1)) {
+        for my $suffix (qw(session system)) {
+
+            my $folder = $index->resolve_path("${prefix}/${suffix}.d");
+            next
+              unless defined $folder;
+
+            push(@files, $folder->children);
+        }
+    }
+
+    my @unique = uniq_by { $_->name } @files;
+
+    $self->check_policy($_) for @unique;
+
+    if (my $folder= $index->resolve_path('usr/share/dbus-1/services')) {
+
+        $self->check_service($_, session => 1) for $folder->children;
+    }
+
+    if (my $folder= $index->resolve_path('usr/share/dbus-1/system-services')) {
+        $self->check_service($_) for $folder->children;
+    }
+
+    return;
+}
+
+my $PROPERTIES = 'org.freedesktop.DBus.Properties';
+
+sub check_policy {
+    my ($self, $item) = @_;
+
+    $self->pointed_hint('dbus-policy-in-etc', $item->pointer)
+      if $item->name =~ m{^etc/};
+
+    my $xml = $item->decoded_utf8;
+    return
+      unless length $xml;
+
+    # Parsing XML via regexes is evil, but good enough here...
+    # note that we are parsing the entire file as one big string,
+    # so that we catch <policy\nat_console="true"\n> or whatever.
+
+    my @rules;
+    # a small rubbish state machine: we want to match a <policy> containing
+    # any <allow> or <deny> rule that is about sending
+    my $policy = $EMPTY;
+    while ($xml =~ m{(<policy[^>]*>)|(</policy\s*>)|(<(?:allow|deny)[^>]*>)}sg)
+    {
+        if (defined $1) {
+            $policy = $1;
+
+        } elsif (defined $2) {
+            $policy = $EMPTY;
+
+        } else {
+            push(@rules, $policy.$3);
+        }
+    }
+
+    my $position = 1;
+    for my $rule (@rules) {
+        # normalize whitespace a bit so we can report it sensibly:
+        # typically it will now look like
+        # <policy context="default"><allow send_destination="com.example.Foo"/>
+        $rule =~ s{\s+}{ }g;
+
+        if ($rule =~ m{send_} && $rule !~ m{send_destination=}) {
+            # It is about sending but does not specify a send-destination.
+            # This could be bad.
+
+            if ($rule =~ m{[^>]*user=['"]root['"].*<allow}) {
+                # skip it: it's probably the "agent" pattern (as seen in
+                # e.g. BlueZ), and cannot normally be a security flaw
+                # because root can do anything anyway
+
+            } else {
+                $self->pointed_hint('dbus-policy-without-send-destination',
+                    $item->pointer($position), $rule);
+
+                if (   $rule =~ m{send_interface=}
+                    && $rule !~ m{send_interface=['"]\Q${PROPERTIES}\E['"]}) {
+                    # That's undesirable, because it opens up communication
+                    # with arbitrary services and can undo DoS mitigation
+                    # efforts; but at least it's specific to an interface
+                    # other than o.fd.DBus.Properties, so all that should
+                    # happen is that the service sends back an error message.
+                    #
+                    # Properties doesn't count as an effective limitation,
+                    # because it's a sort of meta-interface.
+
+                } elsif ($rule =~ m{<allow}) {
+                    # Looks like CVE-2014-8148 or similar. This is really bad;
+                    # emit an additional tag.
+                    $self->pointed_hint('dbus-policy-excessively-broad',
+                        $item->pointer($position), $rule);
+                }
+            }
+        }
+
+        $self->pointed_hint('dbus-policy-at-console',
+            $item->pointer($position), $rule)
+          if $rule =~ m{at_console=['"]true};
+
+    } continue {
+        ++$position;
+    }
+
+    return;
+}
+
+sub check_service {
+    my ($self, $item, %kwargs) = @_;
+
+    my $text = $item->decoded_utf8;
+    return
+      unless length $text;
+
+    while ($text =~ m{^Name=(.*)$}gm) {
+
+        my $name = $1;
+
+        next
+          if $item->basename eq "${name}.service";
+
+        if ($kwargs{session}) {
+            $self->pointed_hint('dbus-session-service-wrong-name',
+                $item->pointer,"better: ${name}.service");
+
+        } else {
+            $self->pointed_hint('dbus-system-service-wrong-name',
+                $item->pointer, "better: ${name}.service");
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Desktop/Gnome.pm b/lib/Lintian/Check/Desktop/Gnome.pm
new file mode 100644
index 0000000..16bb0d1
--- /dev/null
+++ b/lib/Lintian/Check/Desktop/Gnome.pm
@@ -0,0 +1,49 @@
+# desktop/gnome -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Desktop::Gnome;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # /etc/gconf/schemas
+    $self->pointed_hint('package-installs-into-etc-gconf-schemas',
+        $item->pointer)
+      if $item->name =~ m{^etc/gconf/schemas/\S};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Desktop/Gnome/Gir.pm b/lib/Lintian/Check/Desktop/Gnome/Gir.pm
new file mode 100644
index 0000000..6f18594
--- /dev/null
+++ b/lib/Lintian/Check/Desktop/Gnome/Gir.pm
@@ -0,0 +1,166 @@
+# desktop/gnome/gir -- lintian check script for GObject-Introspection -*- perl -*-
+#
+# Copyright (C) 2012 Arno Toell
+# Copyright (C) 2014 Collabora Ltd.
+# Copyright (C) 2016 Simon McVittie
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Desktop::Gnome::Gir;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $DOLLAR => q{$};
+
+const my $NONE => q{NONE};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $debian_control = $self->processable->debian_control;
+
+    for my $installable ($debian_control->installables) {
+
+        $self->pointed_hint('typelib-missing-gir-depends',
+            $debian_control->item->pointer, $installable)
+          if $installable =~ m/^gir1\.2-/
+          && !$self->processable->binary_relation($installable, 'strong')
+          ->satisfies($DOLLAR . '{gir:Depends}');
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $DEB_HOST_MULTIARCH= $self->data->architectures->deb_host_multiarch;
+    my $triplet = $DEB_HOST_MULTIARCH->{$self->processable->architecture};
+
+    # Slightly contrived, but it might be Architecture: all, in which
+    # case this is the best we can do
+    $triplet = $DOLLAR . '{DEB_HOST_MULTIARCH}'
+      unless defined $triplet;
+
+    my $xml_dir
+      = $self->processable->installed->resolve_path('usr/share/gir-1.0/');
+
+    my @girs;
+    @girs = grep { $_->name =~ m{ [.]gir $}x } $xml_dir->children
+      if defined $xml_dir;
+
+    my @type_libs;
+
+    my $old_dir
+      = $self->processable->installed->resolve_path(
+        'usr/lib/girepository-1.0/');
+
+    if (defined $old_dir) {
+
+        $self->pointed_hint('typelib-not-in-multiarch-directory',
+            $_->pointer,"usr/lib/$triplet/girepository-1.0")
+          for $old_dir->children;
+
+        push(@type_libs, $old_dir->children);
+    }
+
+    my $multiarch_dir= $self->processable->installed->resolve_path(
+        "usr/lib/$triplet/girepository-1.0");
+    push(@type_libs, $multiarch_dir->children)
+      if defined $multiarch_dir;
+
+    my $section = $self->processable->fields->value('Section');
+    if ($section ne 'libdevel' && $section ne 'oldlibs') {
+
+        $self->pointed_hint('gir-section-not-libdevel', $_->pointer,
+            $section || $NONE)
+          for @girs;
+    }
+
+    if ($section ne 'introspection' && $section ne 'oldlibs') {
+
+        $self->pointed_hint('typelib-section-not-introspection',
+            $_->pointer, $section || $NONE)
+          for @type_libs;
+    }
+
+    if ($self->processable->architecture eq 'all') {
+
+        $self->pointed_hint('gir-in-arch-all-package', $_->pointer)for @girs;
+
+        $self->pointed_hint('typelib-in-arch-all-package', $_->pointer)
+          for @type_libs;
+    }
+
+  GIR: for my $gir (@girs) {
+
+        my $expected = 'gir1.2-' . lc($gir->basename);
+        $expected =~ s/\.gir$//;
+        $expected =~ tr/_/-/;
+
+        for my $installable ($self->group->get_installables) {
+            next
+              unless $installable->name =~ m/^gir1\.2-/;
+
+            my $name = $installable->name;
+            my $version = $installable->fields->value('Version');
+
+            next GIR
+              if $installable->relation('Provides')->satisfies($expected)
+              && $self->processable->relation('strong')
+              ->satisfies("$name (= $version)");
+        }
+
+        my $our_version = $self->processable->fields->value('Version');
+
+        $self->pointed_hint('gir-missing-typelib-dependency',
+            $gir->pointer, $expected)
+          unless $self->processable->relation('strong')
+          ->satisfies("$expected (= $our_version)");
+    }
+
+    for my $type_lib (@type_libs) {
+
+        my $expected = 'gir1.2-' . lc($type_lib->basename);
+        $expected =~ s/\.typelib$//;
+        $expected =~ tr/_/-/;
+
+        $self->pointed_hint('typelib-package-name-does-not-match',
+            $type_lib->pointer, $expected)
+          if $self->processable->name ne $expected
+          && !$self->processable->relation('Provides')->satisfies($expected);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Desktop/Gnome/Gir/Substvars.pm b/lib/Lintian/Check/Desktop/Gnome/Gir/Substvars.pm
new file mode 100644
index 0000000..d667717
--- /dev/null
+++ b/lib/Lintian/Check/Desktop/Gnome/Gir/Substvars.pm
@@ -0,0 +1,65 @@
+# desktop/gnome/gir/substvars -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Desktop::Gnome::Gir::Substvars;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $DOLLAR => q{$};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $debian_control = $self->processable->debian_control;
+
+    for my $installable ($debian_control->installables) {
+
+        next
+          unless $installable =~ m{ gir [\d.]+ - .* - [\d.]+ $}x;
+
+        my $relation= $self->processable->binary_relation($installable, 'all');
+
+        $self->pointed_hint(
+            'gobject-introspection-package-missing-depends-on-gir-depends',
+            $debian_control->item->pointer,$installable)
+          unless $relation->satisfies($DOLLAR . '{gir:Depends}');
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Desktop/Icons.pm b/lib/Lintian/Check/Desktop/Icons.pm
new file mode 100644
index 0000000..95565ed
--- /dev/null
+++ b/lib/Lintian/Check/Desktop/Icons.pm
@@ -0,0 +1,69 @@
+# desktop/icons -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Desktop::Icons;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    if ($item->name =~ m{/icons/[^/]+/(\d+)x(\d+)/(?!animations/).*\.png$}){
+
+        my $directory_width = $1;
+        my $directory_height = $2;
+
+        my $resolved = $item->resolve_path;
+
+        if ($resolved && $resolved->file_type =~ m/,\s*(\d+)\s*x\s*(\d+)\s*,/){
+
+            my $file_width = $1;
+            my $file_height = $2;
+
+            my $width_delta = abs($directory_width - $file_width);
+            my $height_delta = abs($directory_height - $file_height);
+
+            $self->pointed_hint('icon-size-and-directory-name-mismatch',
+                $item->pointer, $file_width.'x'.$file_height)
+              if $width_delta > 2 || $height_delta > 2;
+        }
+    }
+
+    $self->pointed_hint('raster-image-in-scalable-directory', $item->pointer)
+      if $item->is_file
+      && $item->name =~ m{/icons/[^/]+/scalable/.*\.(?:png|xpm)$};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Desktop/X11.pm b/lib/Lintian/Check/Desktop/X11.pm
new file mode 100644
index 0000000..4373980
--- /dev/null
+++ b/lib/Lintian/Check/Desktop/X11.pm
@@ -0,0 +1,94 @@
+# desktop/x11 -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Desktop::X11;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(any none);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has fontdirs => (is => 'rw', default => sub { {} });
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # links to FHS locations are allowed
+    $self->pointed_hint('package-installs-file-to-usr-x11r6', $item->pointer)
+      if $item->name =~ m{^usr/X11R6/} && !$item->is_symlink;
+
+    return
+      if $item->is_dir;
+
+    # /usr/share/fonts/X11
+    my ($subdir) = ($item->name =~ m{^usr/share/fonts/X11/([^/]+)/\S+});
+    if (defined $subdir) {
+
+        $self->fontdirs->{$subdir}++
+          if any { $subdir eq $_ } qw(100dpi 75dpi misc);
+
+        if (any { $subdir eq $_ } qw(PEX CID Speedo cyrillic)) {
+            $self->pointed_hint('file-in-discouraged-x11-font-directory',
+                $item->pointer);
+
+        } elsif (none { $subdir eq $_ }
+            qw(100dpi 75dpi misc Type1 encodings util)) {
+            $self->pointed_hint('file-in-unknown-x11-font-directory',
+                $item->pointer);
+
+        } elsif ($item->basename eq 'encodings.dir'
+            or $item->basename =~ m{fonts\.(dir|scale|alias)}) {
+            $self->pointed_hint('package-contains-compiled-font-file',
+                $item->pointer);
+        }
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    # X11 font directories with files
+    my %fontdirs = %{$self->fontdirs};
+
+    # check for multiple DPIs in the same X11 bitmap font package.
+    $self->hint('package-contains-multiple-dpi-fonts')
+      if $fontdirs{'100dpi'} && $fontdirs{'75dpi'};
+
+    $self->hint('package-mixes-misc-and-dpi-fonts')
+      if $fontdirs{misc} && keys %fontdirs > 1;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Desktop/X11/Font/Update.pm b/lib/Lintian/Check/Desktop/X11/Font/Update.pm
new file mode 100644
index 0000000..2315e7d
--- /dev/null
+++ b/lib/Lintian/Check/Desktop/X11/Font/Update.pm
@@ -0,0 +1,159 @@
+# desktop/x11/font/update -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Desktop::X11::Font::Update;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+# When detecting commands inside shell scripts, use this regex to match the
+# beginning of the command rather than checking whether the command is at the
+# beginning of a line.
+const my $LEADING_PATTERN=>
+'(?:(?:^|[`&;(|{])\s*|(?:if|then|do|while|!)\s+|env(?:\s+[[:alnum:]_]+=(?:\S+|\"[^"]*\"|\'[^\']*\'))*\s+)';
+const my $LEADING_REGEX => qr/$LEADING_PATTERN/;
+
+has x_fonts => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my @x_fonts
+          = grep { m{^usr/share/fonts/X11/.*\.(?:afm|pcf|pfa|pfb)(?:\.gz)?$} }
+          @{$self->processable->installed->sorted_list};
+
+        return \@x_fonts;
+    }
+);
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_maintainer_script;
+
+    return
+      unless length $item->interpreter;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $stashed = $EMPTY;
+
+    my $saw_update_fonts = 0;
+
+    my $position = 1;
+    while (my $possible_continuation = <$fd>) {
+
+        chomp $possible_continuation;
+
+        # skip empty lines
+        next
+          if $possible_continuation =~ /^\s*$/;
+
+        # skip comment lines
+        next
+          if $possible_continuation =~ /^\s*\#/;
+
+        my $no_comment = remove_comments($possible_continuation);
+
+        # Concatenate lines containing continuation character (\)
+        # at the end
+        if ($no_comment =~ s{\\$}{}) {
+
+            $stashed .= $no_comment;
+
+            next;
+        }
+
+        my $line = $stashed . $no_comment;
+        $stashed = $EMPTY;
+
+        $saw_update_fonts = 1
+          if $line
+          =~ m{$LEADING_REGEX(?:/usr/bin/)?update-fonts-(?:alias|dir|scale)\s(\S+)};
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    if ($item->name eq 'postinst' && !$saw_update_fonts) {
+
+        $self->pointed_hint('missing-call-to-update-fonts', $item->pointer, $_)
+          for @{$self->x_fonts};
+    }
+
+    return;
+}
+
+sub remove_comments {
+    my ($line) = @_;
+
+    return $line
+      unless length $line;
+
+    my $simplified = $line;
+
+    # Remove quoted strings so we can more easily ignore comments
+    # inside them
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\'(?:\\.|[^\\\'])+\'/$1''/g;
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\"(?:\\.|[^\\\"])+\"/$1""/g;
+
+    # If the remaining string contains what looks like a comment,
+    # eat it. In either case, swap the unmodified script line
+    # back in for processing (if required) and return it.
+    if ($simplified =~ m/(?:^|[^[\\])[\s\&;\(\)](\#.*$)/) {
+
+        my $comment = $1;
+
+        # eat comment
+        $line =~ s/\Q$comment\E//;
+    }
+
+    return $line;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/DhMake.pm b/lib/Lintian/Check/DhMake.pm
new file mode 100644
index 0000000..42f8d94
--- /dev/null
+++ b/lib/Lintian/Check/DhMake.pm
@@ -0,0 +1,83 @@
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::DhMake;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    $self->pointed_hint('readme-source-is-dh_make-template', $item->pointer)
+      if $item->name eq 'debian/README.source'
+      && $item->bytes
+      =~ / \QYou WILL either need to modify or delete this file\E /isx;
+
+    if (   $item->name =~ m{^debian/(README.source|copyright|rules|control)$}
+        && $item->is_open_ok) {
+
+        open(my $fd, '<', $item->unpacked_path)
+          or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+        my $position = 1;
+        while (my $line = <$fd>) {
+
+            next
+              unless $line =~ m/(?<!")(FIX_?ME)(?!")/;
+
+            my $placeholder = $1;
+
+            $self->pointed_hint('file-contains-fixme-placeholder',
+                $item->pointer($position), $placeholder);
+
+        } continue {
+            ++$position;
+        }
+
+        close $fd;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/DhMake/Template.pm b/lib/Lintian/Check/DhMake/Template.pm
new file mode 100644
index 0000000..64c1f57
--- /dev/null
+++ b/lib/Lintian/Check/DhMake/Template.pm
@@ -0,0 +1,52 @@
+# dh-make/template -- lintian check script -*- perl -*-
+
+# Copyright (C) 1999 by Joey Hess
+# Copyright (C) 2016-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::DhMake::Template;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->dirname eq 'debian/';
+
+    $self->pointed_hint('dh-make-template-in-source', $item->pointer)
+      if $item->basename =~ m{^ ex[.] | [.]ex $}ix;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Documentation.pm b/lib/Lintian/Check/Documentation.pm
new file mode 100644
index 0000000..364ecde
--- /dev/null
+++ b/lib/Lintian/Check/Documentation.pm
@@ -0,0 +1,246 @@
+# documentation -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Documentation;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any);
+use Unicode::UTF8 qw(encode_utf8);
+
+const my $VERTICAL_BAR => q{|};
+
+# 276 is 255 bytes (maximal length for a filename) plus gzip overhead
+const my $MAXIMUM_EMPTY_GZIP_SIZE => 276;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# a list of regex for detecting non documentation files checked against basename (xi)
+my @NOT_DOCUMENTATION_FILE_REGEXES = qw{
+  ^dependency_links[.]txt$
+  ^entry_points[.]txt$
+  ^requires[.]txt$
+  ^top_level[.]txt$
+  ^requirements[.]txt$
+  ^namespace_packages[.]txt$
+  ^bindep[.]txt$
+  ^version[.]txt$
+  ^robots[.]txt$
+  ^cmakelists[.]txt$
+};
+
+# a list of regex for detecting documentation file checked against basename (xi)
+my @DOCUMENTATION_FILE_REGEXES = qw{
+  [.]docx?$
+  [.]html?$
+  [.]info$
+  [.]latex$
+  [.]markdown$
+  [.]md$
+  [.]odt$
+  [.]pdf$
+  [.]readme$
+  [.]rmd$
+  [.]rst$
+  [.]rtf$
+  [.]tex$
+  [.]txt$
+  ^code[-_]of[-_]conduct$
+  ^contribut(?:e|ing)$
+  ^copyright$
+  ^licen[sc]es?$
+  ^howto$
+  ^patents?$
+  ^readme(?:[.]?first|[.]1st|[.]debian|[.]source)?$
+  ^todos?$
+};
+
+# an OR (|) regex of all compressed extension
+has COMPRESS_FILE_EXTENSIONS_OR_ALL => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $COMPRESS_FILE_EXTENSIONS
+          = $self->data->load('files/compressed-file-extensions',qr/\s+/);
+
+        my $text = join($VERTICAL_BAR,
+            (map { quotemeta } $COMPRESS_FILE_EXTENSIONS->all));
+
+        return qr/$text/;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    my $ppkg = quotemeta($self->processable->name);
+
+    if (   $self->processable->type eq 'udeb'
+        && $item->name =~ m{^usr/share/(?:doc|info)/\S}) {
+
+        $self->pointed_hint('udeb-contains-documentation-file',$item->pointer);
+        return;
+    }
+
+    $self->pointed_hint('package-contains-info-dir-file', $item->pointer)
+      if $item->name =~ m{^ usr/share/info/dir (?:[.]old)? (?:[.]gz)? $}x;
+
+    # doxygen md5sum
+    $self->pointed_hint('useless-autogenerated-doxygen-file', $item->pointer)
+      if $item->name =~ m{^ usr/share/doc/ $ppkg / [^/]+ / .+ [.]md5$ }sx
+      && $item->parent_dir->child('doxygen.png');
+
+    my $regex = $self->COMPRESS_FILE_EXTENSIONS_OR_ALL;
+
+    # doxygen compressed map
+    $self->pointed_hint('compressed-documentation', $item->pointer)
+      if $item->name
+      =~ m{^ usr/share/doc/ (?:.+/)? (?:doxygen|html) / .* [.]map [.] $regex }sx;
+
+    if ($item->is_file
+        and any { $item->basename =~ m{$_}xi } @DOCUMENTATION_FILE_REGEXES
+        and any { $item->basename !~ m{$_}xi } @NOT_DOCUMENTATION_FILE_REGEXES)
+    {
+
+        $self->pointed_hint(
+            'package-contains-documentation-outside-usr-share-doc',
+            $item->pointer)
+          unless $item->name =~ m{^etc/}
+          || $item->name =~ m{^usr/share/(?:doc|help)/}
+          # see Bug#981268
+          # usr/lib/python3/dist-packages/*.dist-info/entry_points.txt
+          || $item->name =~ m{^ usr/lib/python3/dist-packages/
+                              .+ [.] dist-info/entry_points.txt $}sx
+          # No need for dh-r packages to automatically
+          # create overrides if we just allow them all to
+          # begin with.
+          || $item->dirname =~ 'usr/lib/R/site-library/'
+          # SNMP MIB files, see Bug#971427
+          || $item->dirname eq 'usr/share/snmp/mibs/'
+          # see Bug#904852
+          || $item->dirname =~ m{templates?(?:[.]d)?/}
+          || ( $item->basename =~ m{^README}xi
+            && $item->bytes =~ m{this directory}xi)
+          # see Bug#1009679, not documentation, just an unlucky suffix
+          || $item->name =~ m{^var/lib/ocaml/lintian/.+[.]info$}
+          # see Bug#970275
+          || $item->name =~ m{^usr/share/gtk-doc/html/.+[.]html?$};
+    }
+
+    if ($item->name =~ m{^usr/share/doc/\S}) {
+
+        # file not owned by root?
+        unless ($item->identity eq 'root/root' || $item->identity eq '0/0') {
+            $self->pointed_hint('bad-owner-for-doc-file', $item->pointer,
+                $item->identity,'!= root/root (or 0/0)');
+        }
+
+        # executable in /usr/share/doc ?
+        if (   $item->is_file
+            && $item->name !~ m{^usr/share/doc/(?:[^/]+/)?examples/}
+            && $item->is_executable) {
+
+            if ($item->is_script) {
+                $self->pointed_hint('script-in-usr-share-doc', $item->pointer);
+            } else {
+                $self->pointed_hint('executable-in-usr-share-doc',
+                    $item->pointer,(sprintf '%04o', $item->operm));
+            }
+        }
+
+        # zero byte file in /usr/share/doc/
+        if ($item->is_regular_file and $item->size == 0) {
+            # Exceptions: examples may contain empty files for various
+            # reasons, Doxygen generates empty *.map files, and Python
+            # uses __init__.py to mark module directories.
+            unless ($item->name =~ m{^usr/share/doc/(?:[^/]+/)?examples/}
+                || $item->name
+                =~ m{^usr/share/doc/(?:.+/)?(?:doxygen|html)/.*[.]map$}s
+                || $item->name=~ m{^usr/share/doc/(?:.+/)?__init__[.]py$}s){
+
+                $self->pointed_hint('zero-byte-file-in-doc-directory',
+                    $item->pointer);
+            }
+        }
+
+        if (   $item->name =~ / [.]gz $/msx
+            && $item->is_regular_file
+            && $item->size <= $MAXIMUM_EMPTY_GZIP_SIZE
+            && $item->file_type =~ / gzip \s compressed /msx) {
+
+            open(my $fd, '<:gzip', $item->unpacked_path)
+              or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+            my $f = <$fd>;
+            close($fd);
+
+            unless (defined $f and length $f) {
+                $self->pointed_hint('zero-byte-file-in-doc-directory',
+                    $item->pointer);
+            }
+        }
+    }
+
+    # file directly in /usr/share/doc ?
+    $self->pointed_hint('file-directly-in-usr-share-doc', $item->pointer)
+      if $item->is_file
+      && $item->name =~ m{^ usr/share/doc/ [^/]+ $}x;
+
+    # contains an INSTALL file?
+    $self->pointed_hint('package-contains-upstream-installation-documentation',
+        $item->pointer)
+      if $item->name =~ m{^ usr/share/doc/ $ppkg / INSTALL (?: [.] .+ )* $}sx;
+
+    # contains a README for another distribution/platform?
+    $self->pointed_hint('package-contains-readme-for-other-platform-or-distro',
+        $item->pointer)
+      if $item->name =~ m{^usr/share/doc/$ppkg/readme[.]
+                             (?:apple|aix|atari|be|beos|bsd|bsdi
+                               |cygwin|darwin|irix|gentoo|freebsd|mac|macos
+                               |macosx|netbsd|openbsd|osf|redhat|sco|sgi
+                               |solaris|suse|sun|vms|win32|win9x|windows
+                             )(?:[.]txt)?(?:[.]gz)?$}xi;
+
+    # contains a compressed version of objects.inv in
+    # sphinx-generated documentation?
+    $self->pointed_hint('compressed-documentation', $item->pointer)
+      if $item->name
+      =~ m{^ usr/share/doc/ $ppkg / (?: [^/]+ / )+ objects [.]inv [.]gz $}x
+      && $item->file_type =~ m{gzip compressed};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Documentation/Devhelp.pm b/lib/Lintian/Check/Documentation/Devhelp.pm
new file mode 100644
index 0000000..cd186a5
--- /dev/null
+++ b/lib/Lintian/Check/Documentation/Devhelp.pm
@@ -0,0 +1,87 @@
+# documentation/devhelp -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2022 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Documentation::Devhelp;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(none);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# *.devhelp and *.devhelp2 files must be accessible from a directory in
+# the devhelp search path: /usr/share/devhelp/books and
+# /usr/share/gtk-doc/html.  We therefore look for any links in one of
+# those directories to another directory.  The presence of such a link
+# blesses any file below that other directory.
+has reachable_folders => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my @reachable_folders;
+
+        for my $item (@{$self->processable->installed->sorted_list}) {
+
+            # in search path
+            next
+              unless $item->name
+              =~ m{^ usr/share/ (?: devhelp/books | gtk-doc/html ) / }x;
+
+            next
+              unless length $item->link;
+
+            my $followed = $item->link_normalized;
+
+            # drop broken links
+            push(@reachable_folders, $followed)
+              if length $followed;
+        }
+
+        return \@reachable_folders;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # locate Devhelp files not discoverable by Devhelp
+    $self->pointed_hint('stray-devhelp-documentation', $item->pointer)
+      if $item->name =~ m{ [.]devhelp2? (?: [.]gz )? $}x
+      && $item->name !~ m{^ usr/share/ (?: devhelp/books | gtk-doc/html ) / }x
+      && (none { $item->name =~ /^\Q$_\E/ } @{$self->reachable_folders});
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Documentation/Devhelp/Standard.pm b/lib/Lintian/Check/Documentation/Devhelp/Standard.pm
new file mode 100644
index 0000000..05d77db
--- /dev/null
+++ b/lib/Lintian/Check/Documentation/Devhelp/Standard.pm
@@ -0,0 +1,47 @@
+# documentation/devhelp/standard -- lintian check script -*- perl -*-
+
+# Copyright (C) 2022 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Documentation::Devhelp::Standard;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    $self->pointed_hint('old-devhelp-standard', $item->pointer)
+      if $item->name =~ m{ [.]devhelp (?: [.]gz )? $}x;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Documentation/Doxygen.pm b/lib/Lintian/Check/Documentation/Doxygen.pm
new file mode 100644
index 0000000..206a4b8
--- /dev/null
+++ b/lib/Lintian/Check/Documentation/Doxygen.pm
@@ -0,0 +1,75 @@
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Documentation::Doxygen;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    $self->pointed_hint('source-contains-prebuilt-doxygen-documentation',
+        $item->parent_dir->pointer)
+      if $item->basename =~ m{^doxygen.(?:png|sty)$}
+      && $self->processable->source_name ne 'doxygen';
+
+    return
+      unless $item->basename =~ /\.(?:x?html?\d?|xht)$/i;
+
+    my $contents = $item->decoded_utf8;
+    return
+      unless length $contents;
+
+    my $lowercase = lc($contents);
+
+    # Identify and ignore documentation templates by looking
+    # for the use of various interpolated variables.
+    # <http://www.doxygen.nl/manual/config.html#cfg_html_header>
+    $self->pointed_hint('source-contains-prebuilt-doxygen-documentation',
+        $item->pointer)
+      if $lowercase =~ m{<meta \s+ name="generator" \s+ content="doxygen}smx
+      && $lowercase
+      !~ /\$(?:doxygenversion|projectname|projectnumber|projectlogo)\b/;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Documentation/Examples.pm b/lib/Lintian/Check/Documentation/Examples.pm
new file mode 100644
index 0000000..4c1b84a
--- /dev/null
+++ b/lib/Lintian/Check/Documentation/Examples.pm
@@ -0,0 +1,48 @@
+# documentation/examples -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Documentation::Examples;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    $self->pointed_hint('nested-examples-directory', $item->pointer)
+      if $item->is_dir
+      && $item->name =~ m{^usr/share/doc/[^/]+/examples/examples/?$};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Documentation/Manual.pm b/lib/Lintian/Check/Documentation/Manual.pm
new file mode 100644
index 0000000..4171ef6
--- /dev/null
+++ b/lib/Lintian/Check/Documentation/Manual.pm
@@ -0,0 +1,663 @@
+# documentation/manual -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2019-2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Documentation::Manual;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Cwd qw(getcwd);
+use File::Basename;
+use IO::Uncompress::Gunzip qw(gunzip $GunzipError);
+use IPC::Run3;
+use List::Compare;
+use List::SomeUtils qw(any none);
+use Path::Tiny;
+use Text::Balanced qw(extract_delimited);
+use Unicode::UTF8 qw(valid_utf8 decode_utf8 encode_utf8);
+
+use Lintian::Spelling qw(check_spelling);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $COLON => q{:};
+const my $COMMA => q{,};
+const my $DOT => q{.};
+const my $NEWLINE => qq{\n};
+
+const my $USER_COMMAND_SECTION => 1;
+const my $SYSTEM_COMMAND_SECTION => 8;
+
+const my $WAIT_STATUS_SHIFT => 8;
+const my $MINIMUM_SHARED_OBJECT_SIZE => 256;
+const my $WIDE_SCREEN => 120;
+
+has local_manpages => (is => 'rw', default => sub { {} });
+
+sub spelling_tag_emitter {
+    my ($self, $tag_name, $pointer, @orig_args) = @_;
+
+    return sub {
+        return $self->pointed_hint($tag_name, $pointer, @orig_args, @_);
+    };
+}
+
+my @user_locations= qw(bin/ usr/bin/ usr/bin/X11/ usr/bin/mh/ usr/games/);
+my @admin_locations= qw(sbin/ usr/sbin/ usr/libexec/);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # no man pages in udebs
+    return
+      if $self->processable->type eq 'udeb';
+
+    if ($item->name =~ m{^usr/share/man/\S+}) {
+
+        $self->pointed_hint('manual-page-in-udeb', $item->pointer)
+          if $self->processable->type eq 'udeb';
+
+        if ($item->is_dir) {
+            $self->pointed_hint('stray-folder-in-manual', $item->pointer)
+              unless $item->name
+              =~ m{^usr/(?:X11R6|share)/man/(?:[^/]+/)?(?:man\d/)?$};
+
+        } elsif ($item->is_file && $item->is_executable) {
+            $self->pointed_hint('executable-manual-page', $item->pointer);
+        }
+    }
+
+    return
+      unless $item->is_file || $item->is_symlink;
+
+    my ($manpage, $page_path, undef) = fileparse($item);
+
+    if ($page_path eq 'usr/share/man/' && $manpage ne $EMPTY) {
+        $self->pointed_hint('odd-place-for-manual-page', $item->pointer);
+        return;
+    }
+
+    # manual page?
+    my ($subdir) = ($page_path =~ m{^usr/share/man(/\S+)});
+    return
+      unless defined $subdir;
+
+    $self->pointed_hint('build-path-in-manual', $item->pointer)
+      if $item =~ m{/_build_} || $item =~ m{_tmp_buildd};
+
+    $self->pointed_hint('manual-page-with-generic-name', $item->pointer)
+      if $item =~ m{/README\.};
+
+    my ($section) = ($subdir =~ m{^.*man(\d)/$});
+    unless (defined $section) {
+        $self->pointed_hint('odd-place-for-manual-page', $item->pointer);
+        return;
+    }
+
+    my ($language) = ($subdir =~ m{^/([^/]+)/man\d/$});
+    $language //= $EMPTY;
+
+    # The country should not be part of the man page locale
+    # directory unless it's one of the known cases where the
+    # language is significantly different between countries.
+    $self->pointed_hint('country-in-manual', $item->pointer)
+      if $language =~ /_/ && $language !~ /^(?:pt_BR|zh_[A-Z][A-Z])$/;
+
+    my @pieces = split(/\./, $manpage);
+    my $ext = pop @pieces;
+
+    if ($ext ne 'gz') {
+
+        push @pieces, $ext;
+        $self->pointed_hint('uncompressed-manual-page', $item->pointer);
+
+    } elsif ($item->is_file) { # so it's .gz... files first; links later
+
+        if ($item->file_type !~ m/gzip compressed data/) {
+            $self->pointed_hint('wrong-compression-in-manual-page',
+                $item->pointer);
+
+        } elsif ($item->file_type !~ m/max compression/) {
+            $self->pointed_hint('poor-compression-in-manual-page',
+                $item->pointer);
+        }
+    }
+
+    my $fn_section = pop @pieces;
+    my $section_num = $fn_section;
+
+    if (scalar @pieces && $section_num =~ s/^(\d).*$/$1/) {
+
+        my $bin = join($DOT, @pieces);
+        $self->local_manpages->{$bin} = []
+          unless $self->local_manpages->{$bin};
+
+        push @{$self->local_manpages->{$bin}},
+          { file => $item, language => $language, section => $section };
+
+        # number of directory and manpage extension equal?
+        if ($section_num != $section) {
+            $self->pointed_hint('odd-place-for-manual-page', $item->pointer);
+        }
+
+    } else {
+        $self->pointed_hint('wrong-name-for-manual-page', $item->pointer);
+    }
+
+    # check symbolic links to other manual pages
+    if ($item->is_symlink) {
+        if ($item->link =~ m{(^|/)undocumented}) {
+            # undocumented link in /usr/share/man -- possibilities
+            #    undocumented... (if in the appropriate section)
+            #    ../man?/undocumented...
+            #    ../../man/man?/undocumented...
+            #    ../../../share/man/man?/undocumented...
+            #    ../../../../usr/share/man/man?/undocumented...
+            if (
+                (
+                    $item->link =~ m{^undocumented\.([237])\.gz}
+                    && $page_path =~ m{^usr/share/man/man$1}
+                )
+                || $item->link =~ m{^\.\./man[237]/undocumented\.[237]\.gz$}
+                || $item->link
+                =~ m{^\.\./\.\./man/man[237]/undocumented\.[237]\.gz$}
+                || $item->link
+                =~ m{^\.\./\.\./\.\./share/man/man[237]/undocumented\.[237]\.gz$}
+                || $item->link
+                =~ m{^\.\./\.\./\.\./\.\./usr/share/man/man[237]/undocumented\.[237]\.gz$}
+            ) {
+                $self->pointed_hint('undocumented-manual-page',$item->pointer);
+            } else {
+                $self->pointed_hint('broken-link-to-undocumented',
+                    $item->pointer);
+            }
+        }
+    } else { # not a symlink
+
+        my $fd;
+        if ($item->file_type =~ m/gzip compressed/) {
+
+            open($fd, '<:gzip', $item->unpacked_path)
+              or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+        } else {
+
+            open($fd, '<', $item->unpacked_path)
+              or die encode_utf8('Cannot open ' . $item->unpacked_path);
+        }
+
+        my @manfile = <$fd>;
+        close $fd;
+
+        # Is it a .so link?
+        if ($item->size < $MINIMUM_SHARED_OBJECT_SIZE) {
+
+            my ($i, $first) = (0, $EMPTY);
+            do {
+                $first = $manfile[$i++] || $EMPTY;
+            } while ($first =~ /^\.\\"/ && $manfile[$i]); #");
+
+            unless ($first) {
+                $self->pointed_hint('empty-manual-page', $item->pointer);
+                return;
+
+            } elsif ($first =~ /^\.so\s+(.+)?$/) {
+                my $dest = $1;
+                if ($dest =~ m{^([^/]+)/(.+)$}) {
+
+                    my ($manxorlang, $remainder) = ($1, $2);
+
+                    if ($manxorlang !~ /^man\d+$/) {
+                        # then it's likely a language subdir, so let's run
+                        # the other component through the same check
+                        if ($remainder =~ m{^([^/]+)/(.+)$}) {
+
+                            my $rest = $2;
+                            $self->pointed_hint(
+                                'bad-so-link-within-manual-page',
+                                $item->pointer)
+                              unless $rest =~ m{^[^/]+\.\d(?:\S+)?(?:\.gz)?$};
+
+                        } else {
+                            $self->pointed_hint(
+                                'bad-so-link-within-manual-page',
+                                $item->pointer);
+                        }
+                    }
+
+                } else {
+                    $self->pointed_hint('bad-so-link-within-manual-page',
+                        $item->pointer);
+                }
+                return;
+            }
+        }
+
+        # If it's not a .so link, use lexgrog to find out if the
+        # man page parses correctly and make sure the short
+        # description is reasonable.
+        #
+        # This check is currently not applied to pages in
+        # language-specific hierarchies, because those pages are
+        # not currently scanned by mandb (bug #29448), and because
+        # lexgrog can't handle pages in all languages at the
+        # moment, leading to huge numbers of false negatives. When
+        # man-db is fixed, this limitation should be removed.
+        if ($page_path =~ m{/man/man\d/}) {
+
+            delete local $ENV{$_}
+              for grep { $_ ne 'PATH' && $_ ne 'TMPDIR' } keys %ENV;
+            local $ENV{LC_ALL} = 'C.UTF-8';
+
+            my @command = ('lexgrog', $item->unpacked_path);
+
+            my $stdout;
+            my $stderr;
+
+            run3(\@command, \undef, \$stdout, \$stderr);
+
+            my $exitcode = $?;
+            my $status = ($exitcode >> $WAIT_STATUS_SHIFT);
+
+            $self->pointed_hint('bad-whatis-entry', $item->pointer)
+              if $status == 2;
+
+            if ($status != 0 && $status != 2) {
+                my $message = "Non-zero status $status from @command";
+                $message .= $COLON . $NEWLINE . $stderr
+                  if length $stderr;
+
+                warn encode_utf8($message);
+
+            } else {
+                my $desc = $stdout;
+                $desc =~ s/^[^:]+: \"(.*)\"$/$1/;
+
+                if ($desc =~ /(\S+)\s+-\s+manual page for \1/i) {
+                    $self->pointed_hint('useless-whatis-entry',$item->pointer);
+
+                } elsif ($desc =~ /\S+\s+-\s+programs? to do something/i) {
+                    $self->pointed_hint('manual-page-from-template',
+                        $item->pointer);
+                }
+            }
+        }
+
+        # If it's not a .so link, run it through 'man' to check for errors.
+        # If it is in a directory with the standard man layout, cd to the
+        # parent directory before running man so that .so directives are
+        # processed properly.  (Yes, there are man pages that include other
+        # pages with .so but aren't simple links; rbash, for instance.)
+        {
+            delete local $ENV{$_}
+              for grep { $_ ne 'PATH' && $_ ne 'TMPDIR' } keys %ENV;
+            local $ENV{LC_ALL} = 'C.UTF-8';
+
+            local $ENV{MANROFFSEQ} = $EMPTY;
+
+            # set back to 80 when Bug#892423 is fixed in groff
+            local $ENV{MANWIDTH} = $WIDE_SCREEN;
+
+            my $stdout;
+            my $stderr;
+
+            my @command = qw(man --warnings -E UTF-8 -l -Tutf8 -Z);
+            push(@command, $item->unpacked_path);
+
+            my $localdir = path($item->unpacked_path)->parent->stringify;
+            $localdir =~ s{^(.*)/man\d\b}{$1}s;
+
+            my $savedir = getcwd;
+            chdir($localdir)
+              or die encode_utf8('Cannot change directory ' . $localdir);
+
+            run3(\@command, \undef, \$stdout, \$stderr);
+
+            my $exitcode = $?;
+            my $status = ($exitcode >> $WAIT_STATUS_SHIFT);
+
+            my @lines = split(/\n/, $stderr);
+
+            my $position = 1;
+            for my $line (@lines) {
+
+                chomp $line;
+
+                # Devel::Cover causes some annoying deep recursion
+                # warnings and sometimes in our child process.
+                # Filter them out, but only during coverage.
+                next
+                  if $ENV{LINTIAN_COVERAGE}
+                  && $line =~ m{
+                      \A Deep [ ] recursion [ ] on [ ] subroutine [ ]
+                      "[^"]+" [ ] at [ ] .*B/Deparse.pm [ ] line [ ]
+                      \d+}xsm;
+
+                # ignore progress information from man
+                next
+                  if $line =~ /^Reformatting/;
+
+                next
+                  if $line =~ /^\s*$/;
+
+                # ignore errors from gzip; dealt with elsewhere
+                next
+                  if $line =~ /^\bgzip\b/;
+
+                # ignore wrapping failures for Asian man pages (groff problem)
+                if ($language =~ /^(?:ja|ko|zh)/) {
+                    next
+                      if $line =~ /warning \[.*\]: cannot adjust line/;
+                    next
+                      if $line =~ /warning \[.*\]: can\'t break line/;
+                }
+
+                # ignore wrapping failures if they contain URLs (.UE is an
+                # extension for marking the end of a URL).
+                next
+                  if $line
+                  =~ /:(\d+): warning \[.*\]: (?:can\'t break|cannot adjust) line/
+                  && ( $manfile[$1 - 1] =~ m{(?:https?|ftp|file)://.+}i
+                    || $manfile[$1 - 1] =~ m{^\s*\.\s*UE\b});
+
+                # ignore common undefined macros from pod2man << Perl 5.10
+                next
+                  if $line =~ /warning: (?:macro )?\'(?:Tr|IX)\' not defined/;
+
+                $line =~ s/^[^:]+: //;
+                $line =~ s/^<standard input>://;
+
+                $self->pointed_hint('groff-message',
+                    $item->pointer($position), $line);
+            } continue {
+                ++$position;
+            }
+
+            chdir($savedir)
+              or die encode_utf8('Cannot change directory ' . $savedir);
+
+        }
+
+        # Now we search through the whole man page for some common errors
+        my $position = 1;
+        my $seen_python_traceback;
+        for my $line (@manfile) {
+
+            chomp $line;
+
+            next
+              if $line =~ /^\.\\\"/; # comments .\"
+
+            if ($line =~ /^\.TH\s/) {
+
+                # title header
+                my $consumed = $line;
+                $consumed =~ s/ [.]TH \s+ //msx;
+
+                my ($delimited, $after_names) = extract_delimited($consumed);
+                unless (length $delimited) {
+                    $consumed =~ s/ ^ \s* \S+ , //gmsx;
+                    $consumed =~ s/ ^ \s* \S+ //msx;
+                    $after_names = $consumed;
+                }
+
+                my ($th_section) = extract_delimited($after_names);
+                if (length $th_section) {
+
+                    # drop initial delimiter
+                    $th_section =~ s/ ^. //msx;
+
+                    # drop final delimiter
+                    $th_section =~ s/ .$ //msx;
+
+                    # unescape
+                    $th_section =~ s/ [\\](.) /$1/gmsx;
+
+                } elsif (length $after_names
+                    && $after_names =~ / ^ \s* (\S+) /msx) {
+                    $th_section = $1;
+                }
+
+                $self->pointed_hint(
+                    'wrong-manual-section',
+                    $item->pointer($position),
+                    "$fn_section != $th_section"
+                )if length $th_section && fc($th_section) ne fc($fn_section);
+            }
+
+            if (   ($line =~ m{(/usr/(dict|doc|etc|info|man|adm|preserve)/)})
+                || ($line =~ m{(/var/(adm|catman|named|nis|preserve)/)})){
+                # FSSTND dirs in man pages
+                # regexes taken from checks/files
+                $self->pointed_hint('FSSTND-dir-in-manual-page',
+                    $item->pointer($position), $1);
+            }
+
+            if ($line eq '.SH "POD ERRORS"') {
+                $self->pointed_hint('pod-conversion-message',
+                    $item->pointer($position));
+            }
+
+            if ($line =~ /Traceback \(most recent call last\):/) {
+                $self->pointed_hint('python-traceback-in-manpage',
+                    $item->pointer)
+                  unless $seen_python_traceback;
+                $seen_python_traceback = 1;
+            }
+
+            # Check for spelling errors if the manpage is English
+            my $stag_emitter
+              = $self->spelling_tag_emitter('typo-in-manual-page',
+                $item->pointer($position));
+            check_spelling($self->data, $line,
+                $self->group->spelling_exceptions,
+                $stag_emitter, 0)
+              if $page_path =~ m{/man/man\d/};
+
+        } continue {
+            ++$position;
+        }
+    }
+
+    # most man pages are zipped
+    my $bytes;
+    if ($item->file_type =~ /gzip compressed/) {
+
+        my $path = $item->unpacked_path;
+        gunzip($path => \$bytes)
+          or die encode_utf8("gunzip $path failed: $GunzipError");
+
+    } elsif ($item->file_type =~ /^troff/ || $item->file_type =~ /text$/) {
+        $bytes = $item->bytes;
+    }
+
+    return
+      unless length $bytes;
+
+    # another check complains about invalid encoding
+    return
+      unless valid_utf8($bytes);
+
+    my $contents = decode_utf8($bytes);
+    my @lines = split(/\n/, $contents);
+
+    my $position = 1;
+    for my $line (@lines) {
+
+        # see Bug#554897 and Bug#507673; exclude string variables
+        $self->pointed_hint('acute-accent-in-manual-page',
+            $item->pointer($position))
+          if $line =~ /\\'/ && $line !~ /^\.\s*ds\s/;
+
+    } continue {
+        $position++;
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    # no man pages in udebs
+    return
+      if $self->processable->type eq 'udeb';
+
+    my %local_user_executables;
+    my %local_admin_executables;
+
+    for my $item (@{$self->processable->installed->sorted_list}) {
+
+        next
+          unless $item->is_symlink || $item->is_file;
+
+        my ($name, $path, undef) = fileparse($item->name);
+
+        $local_user_executables{$name} = $item
+          if any { $path eq $_ } @user_locations;
+
+        $local_admin_executables{$name} = $item
+          if any { $path eq $_ } @admin_locations;
+    }
+
+    my %local_executables= (%local_user_executables, %local_admin_executables);
+    my @local_commands = keys %local_executables;
+
+    my @direct_reliants
+      =@{$self->group->direct_reliants($self->processable) // []};
+    my @reliant_files = map { @{$_->installed->sorted_list} } @direct_reliants;
+
+    # for executables, look at packages relying on the current processable
+    my %distant_executables;
+    for my $item (@reliant_files) {
+
+        next
+          unless $item->is_file || $item->is_symlink;
+
+        my ($name, $path, undef) = fileparse($item, qr{\..+$});
+
+        $distant_executables{$name} = $item
+          if any { $path eq $_ } (@user_locations, @admin_locations);
+    }
+
+    my @distant_commands = keys %distant_executables;
+    my @related_commands = (@local_commands, @distant_commands);
+
+    my @direct_prerequisites
+      =@{$self->group->direct_dependencies($self->processable) // []};
+    my@prerequisite_files
+      = map { @{$_->installed->sorted_list} } @direct_prerequisites;
+
+    # for manpages, look at packages the current processable relies upon
+    my %distant_manpages;
+    for my $item (@prerequisite_files) {
+
+        next
+          unless $item->is_file || $item->is_symlink;
+
+        my ($name, $path, undef) = fileparse($item, qr{\..+$});
+
+        next
+          unless $path =~ m{^usr/share/man/\S+};
+
+        next
+          unless $path =~ m{man\d/$};
+
+        my ($language) = ($path =~ m{/([^/]+)/man\d/$});
+        $language //= $EMPTY;
+        $language = $EMPTY if $language eq 'man';
+
+        $distant_manpages{$name} //= [];
+
+        push @{$distant_manpages{$name}},
+          {file => $item, language => $language};
+    }
+
+    my %local_manpages = %{$self->local_manpages};
+    my %related_manpages = (%local_manpages, %distant_manpages);
+
+    # provides sorted output
+    my $related
+      = List::Compare->new(\@local_commands, [keys %related_manpages]);
+    my @documented = $related->get_intersection;
+    my @manpage_missing = $related->get_Lonly;
+
+    my @english_missing = grep {
+        none {$_->{language} eq $EMPTY}
+          @{$related_manpages{$_} // []}
+    } @documented;
+
+    for my $command (keys %local_admin_executables) {
+
+        my $item = $local_admin_executables{$command};
+        my @manpages = @{$related_manpages{$command} // []};
+
+        my @sections = grep { defined } map { $_->{section} } @manpages;
+        $self->pointed_hint('manual-page-for-system-command', $item->pointer)
+          if $item->is_regular_file
+          && any { $_ == $USER_COMMAND_SECTION } @sections;
+    }
+
+    for (map {$local_executables{$_}} @english_missing) {
+        $self->pointed_hint('no-english-manual-page', $_->pointer)
+          unless $_->name =~ m{/libexec/};
+    }
+
+    for (map {$local_executables{$_}} @manpage_missing) {
+        $self->pointed_hint('no-manual-page', $_->pointer)
+          unless $_->name =~ m{/libexec/};
+    }
+
+    # surplus manpages only for this package; provides sorted output
+    my $local = List::Compare->new(\@related_commands, [keys %local_manpages]);
+    my @surplus_manpages = $local->get_Ronly;
+
+    # filter out sub commands, underscore for libreswan; see Bug#947258
+    for my $command (@related_commands) {
+        @surplus_manpages = grep { !/^$command(?:\b|_)/ } @surplus_manpages;
+    }
+
+    for my $manpage (map { @{$local_manpages{$_} // []} } @surplus_manpages) {
+
+        my $item = $manpage->{file};
+        my $section = $manpage->{section};
+
+        $self->pointed_hint('spare-manual-page', $item->pointer)
+          if $section == $USER_COMMAND_SECTION
+          || $section == $SYSTEM_COMMAND_SECTION;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Documentation/Texinfo.pm b/lib/Lintian/Check/Documentation/Texinfo.pm
new file mode 100644
index 0000000..cc4be39
--- /dev/null
+++ b/lib/Lintian/Check/Documentation/Texinfo.pm
@@ -0,0 +1,195 @@
+# documentation/texinfo -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2001 Josip Rodin
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Documentation::Texinfo;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+use List::SomeUtils qw(uniq);
+
+use Lintian::Util qw(normalize_link_target);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+sub binary {
+    my ($self) = @_;
+
+    my $info_dir
+      = $self->processable->installed->resolve_path('usr/share/info/');
+    return
+      unless $info_dir;
+
+    # Read package contents...
+    for my $item ($info_dir->descendants) {
+
+        next
+          unless $item->is_symlink
+          || $item->is_file;
+
+        # Ignore dir files.  That's a different error which we already catch in
+        # the files check.
+        next
+          if $item->basename =~ /^dir(?:\.old)?(?:\.gz)?/;
+
+        # Analyze the file names making sure the documents are named
+        # properly.  Note that Emacs 22 added support for images in
+        # info files, so we have to accept those and ignore them.
+        # Just ignore .png files for now.
+        my @fname_pieces = split(m{ [.] }x, $item->basename);
+        my $extension = pop @fname_pieces;
+
+        if ($extension eq 'gz') { # ok!
+            if ($item->is_file) {
+
+                # compressed with maximum compression rate?
+                if ($item->file_type !~ m/gzip compressed data/) {
+                    $self->pointed_hint(
+                        'info-document-not-compressed-with-gzip',
+                        $item->pointer);
+
+                } else {
+                    if ($item->file_type !~ m/max compression/) {
+                        $self->pointed_hint(
+'info-document-not-compressed-with-max-compression',
+                            $item->pointer
+                        );
+                    }
+                }
+            }
+
+        } elsif ($extension =~ m/^(?:png|jpe?g)$/) {
+            next;
+
+        } else {
+            push(@fname_pieces, $extension);
+            $self->pointed_hint('info-document-not-compressed',$item->pointer);
+        }
+
+        my $infoext = pop @fname_pieces;
+        unless ($infoext && $infoext =~ /^info(-\d+)?$/) { # it's not foo.info
+
+            # it's not foo{,-{1,2,3,...}}
+            $self->pointed_hint('info-document-has-wrong-extension',
+                $item->pointer)
+              if @fname_pieces;
+        }
+
+        # If this is the main info file (no numeric extension). make
+        # sure it has appropriate dir entry information.
+        if (   $item->basename !~ /-\d+\.gz/
+            && $item->file_type =~ /gzip compressed data/) {
+
+            # unsafe symlink, skip.  Actually, this should never
+            # be true as "$file_type" for symlinks will not be
+            # "gzip compressed data".  But for good measure.
+            next
+              unless $item->is_open_ok;
+
+            open(my $fd, '<:gzip', $item->unpacked_path)
+              or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+            my ($section, $start, $end);
+            while (my $line = <$fd>) {
+
+                $section = 1
+                  if $line =~ /^INFO-DIR-SECTION\s+\S/;
+
+                $start   = 1
+                  if $line =~ /^START-INFO-DIR-ENTRY\b/;
+
+                $end     = 1
+                  if $line =~ /^END-INFO-DIR-ENTRY\b/;
+            }
+
+            close $fd;
+
+            $self->pointed_hint('info-document-missing-dir-section',
+                $item->pointer)
+              unless $section;
+
+            $self->pointed_hint('info-document-missing-dir-entry',
+                $item->pointer)
+              unless $start && $end;
+        }
+
+        # Check each [image src=""] form in the info files.  The src
+        # filename should be in the package.  As of Texinfo 5 it will
+        # be something.png or something.jpg, but that's not enforced.
+        #
+        # See Texinfo manual (info "(texinfo)Info Format Image") for
+        # details of the [image] form.  Bytes \x00,\x08 introduce it
+        # (and distinguishes it from [image] appearing as plain text).
+        #
+        # String src="..." part has \" for literal " and \\ for
+        # literal \, though that would be unlikely in filenames.  For
+        # the tag() message show $src unbackslashed since that's the
+        # filename sought.
+        #
+        if ($item->is_file && $item->basename =~ /\.info(?:-\d+)?\.gz$/) {
+
+            open(my $fd, '<:gzip', $item->unpacked_path)
+              or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+            my $position = 1;
+            while (my $line = <$fd>) {
+
+                my @missing;
+                while ($line =~ /[\0][\b]\[image src="((?:\\.|[^\"])+)"/smg) {
+
+                    my $src = $1;
+                    $src =~ s/\\(.)/$1/g;   # unbackslash
+
+                    push(@missing, $src)
+                      unless $self->processable->installed->lookup(
+                        normalize_link_target('usr/share/info', $src));
+                }
+
+                $self->pointed_hint('info-document-missing-image-file',
+                    $item->pointer($position), $_)
+                  for uniq @missing;
+
+            } continue {
+                ++$position;
+            }
+
+            close $fd;
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Emacs.pm b/lib/Lintian/Check/Emacs.pm
new file mode 100644
index 0000000..6c6f94e
--- /dev/null
+++ b/lib/Lintian/Check/Emacs.pm
@@ -0,0 +1,58 @@
+# emacs -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Emacs;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $WIDELY_READABLE => oct(644);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # /etc/emacs.*
+    if (   $item->is_file
+        && $item->name =~ m{^etc/emacs.*/\S}
+        && $item->operm != $WIDELY_READABLE) {
+
+        $self->pointed_hint('bad-permissions-for-etc-emacs-script',
+            $item->pointer,
+            sprintf('%04o != %04o', $item->operm, $WIDELY_READABLE));
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Emacs/Elpa.pm b/lib/Lintian/Check/Emacs/Elpa.pm
new file mode 100644
index 0000000..9b3528a
--- /dev/null
+++ b/lib/Lintian/Check/Emacs/Elpa.pm
@@ -0,0 +1,51 @@
+# emacs/elpa -- lintian check script -*- perl -*-
+
+# Copyright (C) 2017 Sean Whitton
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Emacs::Elpa;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub installable {
+    my ($self) = @_;
+
+    $self->hint('emacsen-common-without-dh-elpa')
+      if defined $self->processable->installed->lookup(
+        'usr/lib/emacsen-common/packages/install/')
+      && !
+      defined $self->processable->installed->lookup(
+        'usr/share/emacs/site-lisp/elpa-src/');
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Examples.pm b/lib/Lintian/Check/Examples.pm
new file mode 100644
index 0000000..ef9a452
--- /dev/null
+++ b/lib/Lintian/Check/Examples.pm
@@ -0,0 +1,82 @@
+# Check::Examples -- lintian check script -*- perl -*-
+#
+# based on debhelper check,
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Examples;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(any);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has group_ships_examples => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my @processables = $self->group->get_installables;
+
+        # assume shipped examples if there is a package so named
+        return 1
+          if any { $_->name =~ m{-examples$} } @processables;
+
+        my @shipped = map { @{$_->installed->sorted_list} } @processables;
+
+        # Check each package for a directory (or symlink) called "examples".
+        return 1
+          if any { m{^usr/share/doc/(.+/)?examples/?$} } @shipped;
+
+        return 0;
+    }
+);
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    # some installation files must be present; see Bug#972614
+    $self->pointed_hint('package-does-not-install-examples', $item->pointer)
+      if $item->basename eq 'examples'
+      && $item->dirname !~ m{(?:^|/)(?:vendor|third_party)/}
+      && $self->group->get_installables
+      && !$self->group_ships_examples;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Executable.pm b/lib/Lintian/Check/Executable.pm
new file mode 100644
index 0000000..37fcb67
--- /dev/null
+++ b/lib/Lintian/Check/Executable.pm
@@ -0,0 +1,59 @@
+# executable -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Executable;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    $self->pointed_hint('executable-not-elf-or-script', $item->pointer)
+      if $item->is_executable
+      && $item->file_type !~ / ^ [^,]* \b ELF \b /msx
+      && !$item->is_script
+      && !$item->is_hardlink
+      && $item->name !~ m{^ usr(?:/X11R6)?/man/ }x
+      && $item->name !~ m/ [.]exe $/x # mono convention
+      && $item->name !~ m/ [.]jar $/x; # Debian Java policy 2.2
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Architecture.pm b/lib/Lintian/Check/Fields/Architecture.pm
new file mode 100644
index 0000000..caa5814
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Architecture.pm
@@ -0,0 +1,132 @@
+# fields/architecture -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Architecture;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::Compare;
+use List::SomeUtils qw(any);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+has installable_architecture => (is => 'rw', default => $EMPTY);
+
+sub installable {
+    my ($self) = @_;
+
+    my @installable_architectures
+      = $self->processable->fields->trimmed_list('Architecture');
+    return
+      unless @installable_architectures;
+
+    for my $installable_architecture (@installable_architectures) {
+        $self->hint('arch-wildcard-in-binary-package',
+            $installable_architecture)
+          if $self->data->architectures->is_wildcard(
+            $installable_architecture);
+    }
+
+    $self->hint('too-many-architectures', (sort @installable_architectures))
+      if @installable_architectures > 1;
+
+    my $installable_architecture = $installable_architectures[0];
+
+    $self->hint('aspell-package-not-arch-all')
+      if $self->processable->name =~ /^aspell-[a-z]{2}(?:-.*)?$/
+      && $installable_architecture ne 'all';
+
+    $self->hint('documentation-package-not-architecture-independent')
+      if $self->processable->name =~ /-docs?$/
+      && $installable_architecture ne 'all';
+
+    return;
+}
+
+sub always {
+    my ($self) = @_;
+
+    my @installable_architectures
+      = $self->processable->fields->trimmed_list('Architecture');
+    for my $installable_architecture (@installable_architectures) {
+
+        $self->hint('unknown-architecture', $installable_architecture)
+          unless $self->data->architectures->is_release_architecture(
+            $installable_architecture)
+          || $self->data->architectures->is_wildcard($installable_architecture)
+          || $installable_architecture eq 'all'
+          || (
+            $installable_architecture eq 'source'
+            && (   $self->processable->type eq 'changes'
+                || $self->processable->type eq 'buildinfo')
+          );
+    }
+
+    # check for magic installable architecture combinations
+    if (@installable_architectures > 1) {
+
+        my $magic_error = 0;
+
+        if (any { $_ eq 'all' } @installable_architectures) {
+            $magic_error++
+              unless any { $self->processable->type eq $_ }
+              qw(source changes buildinfo);
+        }
+
+        my $anylc = List::Compare->new(\@installable_architectures, ['any']);
+        if ($anylc->get_intersection) {
+
+            my @errorset = $anylc->get_Lonly;
+
+            # Allow 'all' to be present in source packages as well
+            # (#626775)
+            @errorset = grep { $_ ne 'all' } @errorset
+              if any { $self->processable->type eq $_ }
+              qw(source changes buildinfo);
+
+            $magic_error++
+              if @errorset;
+        }
+
+        $self->hint('magic-arch-in-arch-list') if $magic_error;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Bugs.pm b/lib/Lintian/Check/Fields/Bugs.pm
new file mode 100644
index 0000000..6485650
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Bugs.pm
@@ -0,0 +1,62 @@
+# fields/bugs -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Bugs;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub always {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    return
+      unless $fields->declares('Bugs');
+
+    my $bugs = $fields->unfolded_value('Bugs');
+
+    $self->hint('redundant-bugs-field')
+      if $bugs =~ m{^debbugs://bugs.debian.org/?$}i;
+
+    $self->hint('bugs-field-does-not-refer-to-debian-infrastructure', $bugs)
+      unless $bugs =~ m{\.debian\.org}
+      || $self->processable->name =~ /[-]dbgsym$/;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/BuiltUsing.pm b/lib/Lintian/Check/Fields/BuiltUsing.pm
new file mode 100644
index 0000000..5da9475
--- /dev/null
+++ b/lib/Lintian/Check/Fields/BuiltUsing.pm
@@ -0,0 +1,72 @@
+# fields/built-using -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::BuiltUsing;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::Relation;
+use Lintian::Util qw($PKGNAME_REGEX $PKGVERSION_REGEX);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub always {
+    my ($self) = @_;
+
+    my $processable = $self->processable;
+
+    return
+      unless $processable->fields->declares('Built-Using');
+
+    my $built_using = $processable->fields->value('Built-Using');
+
+    my $built_using_rel = Lintian::Relation->new->load($built_using);
+    $built_using_rel->visit(
+        sub {
+            my ($package) = @_;
+            if ($package !~ /^$PKGNAME_REGEX \(= $PKGVERSION_REGEX\)$/) {
+                $self->hint('invalid-value-in-built-using-field', $package);
+                return 1;
+            }
+            return 0;
+        },
+        Lintian::Relation::VISIT_OR_CLAUSE_FULL
+          | Lintian::Relation::VISIT_STOP_FIRST_MATCH
+    );
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/ChangedBy.pm b/lib/Lintian/Check/Fields/ChangedBy.pm
new file mode 100644
index 0000000..4f58b1b
--- /dev/null
+++ b/lib/Lintian/Check/Fields/ChangedBy.pm
@@ -0,0 +1,66 @@
+# changed-by -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software.  It is distributed under the terms of
+# the GNU General Public License as published by the Free Software
+# Foundation; either version 2 of the License, or (at your option) any
+# later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::ChangedBy;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub changes {
+    my ($self) = @_;
+
+    # Changed-By is optional in Policy, but if set, must be
+    # syntactically correct.  It's also used by dak.
+    return
+      unless $self->processable->fields->declares('Changed-By');
+
+    my $changed_by = $self->processable->fields->value('Changed-By');
+
+    my $DERIVATIVE_CHANGED_BY
+      = $self->data->load('common/derivative-changed-by',qr/\s*~~\s*/);
+
+    for my $regex ($DERIVATIVE_CHANGED_BY->all) {
+
+        next
+          if $changed_by =~ /$regex/;
+
+        my $explanation = $DERIVATIVE_CHANGED_BY->value($regex);
+        $self->hint('changed-by-invalid-for-derivative',
+            $changed_by, "($explanation)");
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Checksums.pm b/lib/Lintian/Check/Fields/Checksums.pm
new file mode 100644
index 0000000..2ea745e
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Checksums.pm
@@ -0,0 +1,53 @@
+# fields/checksums -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Checksums;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $processable = $self->processable;
+
+    $self->hint('no-strong-digests-in-dsc')
+      unless $processable->fields->declares('Checksums-Sha256');
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Deb822.pm b/lib/Lintian/Check/Fields/Deb822.pm
new file mode 100644
index 0000000..d68fa6c
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Deb822.pm
@@ -0,0 +1,89 @@
+# fields/deb822 -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Deb822;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Syntax::Keyword::Try;
+
+use Lintian::Deb822;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SECTION => qq{\N{SECTION SIGN}};
+
+my @SOURCE_DEB822 = qw(debian/control);
+
+sub source {
+    my ($self) = @_;
+
+    for my $location (@SOURCE_DEB822) {
+
+        my $item = $self->processable->patched->resolve_path($location);
+        return
+          unless defined $item;
+
+        my $deb822 = Lintian::Deb822->new;
+
+        my @sections;
+        try {
+            @sections = $deb822->read_file($item->unpacked_path)
+
+        } catch {
+            next;
+        }
+
+        my $count = 1;
+        for my $section (@sections) {
+
+            for my $field_name ($section->names) {
+
+                my $field_value = $section->value($field_name);
+
+                my $position = $section->position($field_name);
+                my $pointer = $item->pointer($position);
+
+                $self->pointed_hint('trimmed-deb822-field', $pointer,
+                    $SECTION . $count,
+                    $field_name, $field_value);
+            }
+
+        } continue {
+            $count++;
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Derivatives.pm b/lib/Lintian/Check/Fields/Derivatives.pm
new file mode 100644
index 0000000..4f42765
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Derivatives.pm
@@ -0,0 +1,88 @@
+# fields/derivatives -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Derivatives;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $HYPHEN => q{-};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has DERIVATIVE_FIELDS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %fields;
+
+        my $data= $self->data->load('fields/derivative-fields',qr/\s*\~\~\s*/);
+
+        for my $key ($data->all) {
+
+            my $value = $data->value($key);
+            my ($regexp, $explanation) = split(/\s*\~\~\s*/, $value, 2);
+            $fields{$key} = {
+                'regexp' => qr/$regexp/,
+                'explanation' => $explanation,
+            };
+        }
+
+        return \%fields;
+    }
+);
+
+sub source {
+    my ($self) = @_;
+
+    my $processable = $self->processable;
+
+    for my $field (keys %{$self->DERIVATIVE_FIELDS}) {
+
+        my $val = $processable->fields->value($field) || $HYPHEN;
+        my $data = $self->DERIVATIVE_FIELDS->{$field};
+
+        $self->hint('invalid-field-for-derivative',
+            "$field: $val ($data->{'explanation'})")
+          if $val !~ m/$data->{'regexp'}/;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Description.pm b/lib/Lintian/Check/Fields/Description.pm
new file mode 100644
index 0000000..9bfd5bc
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Description.pm
@@ -0,0 +1,323 @@
+# fields/description -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Description;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Lintian::Spelling qw(check_spelling check_spelling_picky);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# Compared to a lower-case string, so it must be all lower-case
+const my $DH_MAKE_PERL_TEMPLATE =>
+'this description was automagically extracted from the module by dh-make-perl';
+
+const my $EMPTY => q{};
+const my $SLASH => q{/};
+const my $DOUBLE_COLON => q{::};
+
+const my $MAXIMUM_WIDTH => 80;
+
+sub spelling_tag_emitter {
+    my ($self, @orig_args) = @_;
+    return sub {
+        return $self->hint(@orig_args, @_);
+    };
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $pkg = $self->processable->name;
+    my $type = $self->processable->type;
+    my $processable = $self->processable;
+    my $group = $self->group;
+
+    my $tabs = 0;
+    my $template = 0;
+    my $unindented_list = 0;
+
+    return
+      unless $processable->fields->declares('Description');
+
+    my $full_description= $processable->fields->untrimmed_value('Description');
+
+    $full_description =~ m/^([^\n]*)\n(.*)$/s;
+    my ($synopsis, $extended) = ($1, $2);
+    unless (defined $synopsis) {
+        # The first line will always be completely stripped but
+        # continuations may have leading whitespace.  Therefore we
+        # have to strip $full_description to restore this property,
+        # when we use it as a fall-back value of the synopsis.
+        $synopsis = $full_description;
+
+        # trim both ends
+        $synopsis =~ s/^\s+|\s+$//g;
+
+        $extended = $EMPTY;
+    }
+
+    $extended //= $EMPTY;
+
+    if ($synopsis =~ m/^\s*$/) {
+        $self->hint('description-synopsis-is-empty');
+    } else {
+        if ($synopsis =~ m/^\Q$pkg\E\b/i) {
+            $self->hint('description-starts-with-package-name');
+        }
+        if ($synopsis =~ m/^(an?|the)\s/i) {
+            $self->hint('description-synopsis-starts-with-article');
+        }
+        if ($synopsis =~ m/(.*\.)(?:\s*$|\s+\S+)/i) {
+            $self->hint('synopsis-is-a-sentence',"\"$synopsis\"")
+              unless $1 =~ m/\s+etc\.$/
+              or $1 =~ m/\s+e\.?g\.$/
+              or $1 =~ m/(?<!\.)\.\.\.$/;
+        }
+        if ($synopsis =~ m/\t/) {
+            $self->hint('description-contains-tabs') unless $tabs++;
+        }
+
+        $self->hint('odd-mark-in-description',
+            'comma not followed by whitespace (synopsis)')
+          if $synopsis =~ /,[^\s\d]/;
+
+        if ($synopsis =~ m/^missing\s*$/i) {
+            $self->hint('description-is-debmake-template') unless $template++;
+        } elsif ($synopsis =~ m/<insert up to 60 chars description>/) {
+            $self->hint('description-is-dh_make-template') unless $template++;
+        }
+        if ($synopsis !~ m/\s/) {
+            $self->hint('description-too-short', $synopsis);
+        }
+        my $pkg_fmt = lc $pkg;
+        my $synopsis_fmt = lc $synopsis;
+        # made a fuzzy match
+        $pkg_fmt =~ s/[-_]/ /g;
+        $synopsis_fmt =~ s{[-_/\\]}{ }g;
+        $synopsis_fmt =~ s/\s+/ /g;
+        if ($pkg_fmt eq $synopsis_fmt) {
+            $self->hint('description-is-pkg-name', $synopsis);
+        }
+
+        $self->hint('synopsis-too-long')
+          if length $synopsis > $MAXIMUM_WIDTH;
+    }
+
+    my $PLANNED_FEATURES= $self->data->load('description/planned-features');
+
+    my $flagged_homepage;
+    my @lines = split(/\n/, $extended);
+
+    # count starts for extended description
+    my $position = 1;
+    for my $line (@lines) {
+        next
+          if $line =~ /^ \.\s*$/;
+
+        if ($position == 1) {
+            my $firstline = lc $line;
+            my $lsyn = lc $synopsis;
+            if ($firstline =~ /^\Q$lsyn\E$/) {
+                $self->hint('description-synopsis-is-duplicated',
+                    "line $position");
+            } else {
+                $firstline =~ s/[^a-zA-Z0-9]+//g;
+                $lsyn =~ s/[^a-zA-Z0-9]+//g;
+                if ($firstline eq $lsyn) {
+                    $self->hint('description-synopsis-is-duplicated',
+                        "line $position");
+                }
+            }
+        }
+
+        if ($line =~ /^ \.\s*\S/ || $line =~ /^ \s+\.\s*$/) {
+            $self->hint('description-contains-invalid-control-statement',
+                "line $position");
+        } elsif ($line =~ /^ [\-\*]/) {
+       # Print it only the second time.  Just one is not enough to be sure that
+       # it's a list, and after the second there's no need to repeat it.
+            $self->hint('possible-unindented-list-in-extended-description',
+                "line $position")
+              if $unindented_list++ == 2;
+        }
+
+        if ($line =~ /\t/) {
+            $self->hint('description-contains-tabs', "line $position")
+              unless $tabs++;
+        }
+
+        if ($line =~ m{^\s*Homepage: <?https?://}i) {
+            $self->hint('description-contains-homepage', "line $position");
+            $flagged_homepage = 1;
+        }
+
+        if ($PLANNED_FEATURES->matches_any($line, 'i')) {
+            $self->hint('description-mentions-planned-features',
+                "(line $position)");
+        }
+
+        $self->hint('odd-mark-in-description',
+            "comma not followed by whitespace (line $position)")
+          if $line =~ /,[^\s\d]/;
+
+        $self->hint('description-contains-dh-make-perl-template',
+            "line $position")
+          if lc($line) =~ / \Q$DH_MAKE_PERL_TEMPLATE\E /msx;
+
+        my $first_person = $line;
+        my %seen;
+        while ($first_person
+            =~ m/(?:^|\s)(I|[Mm]y|[Oo]urs?|mine|myself|me|us|[Ww]e)(?:$|\s)/) {
+            my $word = $1;
+            $first_person =~ s/\Q$word//;
+            $self->hint('using-first-person-in-description',
+                "line $position: $word")
+              unless $seen{$word}++;
+        }
+
+        if ($position == 1) {
+            # checks for the first line of the extended description:
+            if ($line =~ /^ \s/) {
+                $self->hint('description-starts-with-leading-spaces',
+                    "line $position");
+            }
+            if ($line =~ /^\s*missing\s*$/i) {
+                $self->hint('description-is-debmake-template',"line $position")
+                  unless $template++;
+            } elsif (
+                $line =~ /<insert long description, indented with spaces>/) {
+                $self->hint('description-is-dh_make-template',"line $position")
+                  unless $template++;
+            }
+        }
+
+        $self->hint('extended-description-line-too-long', "line $position")
+          if length $line > $MAXIMUM_WIDTH;
+
+    } continue {
+        ++$position;
+    }
+
+    if ($type ne 'udeb') {
+        if (@lines == 0) {
+            # Ignore debug packages with empty "extended" description
+            # "debug symbols for pkg foo" is generally descriptive
+            # enough.
+            $self->hint('extended-description-is-empty')
+              unless $processable->is_debug_package;
+
+        } elsif (@lines < 2 && $synopsis !~ /(?:dummy|transition)/i) {
+            $self->hint('extended-description-is-probably-too-short')
+              unless $processable->is_transitional
+              || $processable->is_meta_package
+              || $pkg =~ m{-dbg\Z}xsm;
+
+        } elsif ($extended =~ /^ \.\s*\n|\n \.\s*\n \.\s*\n|\n \.\s*\n?$/) {
+            $self->hint('extended-description-contains-empty-paragraph');
+        }
+    }
+
+    # Check for a package homepage in the description and no Homepage
+    # field.  This is less accurate and more of a guess than looking
+    # for the old Homepage: convention in the body.
+    unless ($processable->fields->declares('Homepage') or $flagged_homepage) {
+        if (
+            $extended =~ m{homepage|webpage|website|url|upstream|web\s+site
+                         |home\s+page|further\s+information|more\s+info
+                         |official\s+site|project\s+home}xi
+            && $extended =~ m{\b(https?://[a-z0-9][^>\s]+)}i
+        ) {
+            $self->hint('description-possibly-contains-homepage', $1);
+        } elsif ($extended =~ m{\b(https?://[a-z0-9][^>\s]+)>?\.?\s*\z}i) {
+            $self->hint('description-possibly-contains-homepage', $1);
+        }
+    }
+
+    if ($synopsis) {
+        check_spelling(
+            $self->data,
+            $synopsis,
+            $group->spelling_exceptions,
+            $self->spelling_tag_emitter(
+                'spelling-error-in-description-synopsis')
+        );
+        # Auto-generated dbgsym packages will use the package name in
+        # their synopsis.  Unfortunately, some package names trigger a
+        # capitalization error, such as "dbus" -> "D-Bus".  Therefore,
+        # we exempt auto-generated packages from this check.
+        check_spelling_picky(
+            $self->data,
+            $synopsis,
+            $self->spelling_tag_emitter(
+                'capitalization-error-in-description-synopsis')
+        ) unless $processable->is_auto_generated;
+    }
+
+    if ($extended) {
+        check_spelling(
+            $self->data,$extended,
+            $group->spelling_exceptions,
+            $self->spelling_tag_emitter('spelling-error-in-description')
+        );
+        check_spelling_picky($self->data, $extended,
+            $self->spelling_tag_emitter('capitalization-error-in-description')
+        );
+    }
+
+    if ($pkg =~ /^lib(.+)-perl$/) {
+        my $mod = $1;
+        my @mod_path_elements = split(/-/, $mod);
+        $mod = join($DOUBLE_COLON, map {ucfirst} @mod_path_elements);
+        my $mod_lc = lc($mod);
+
+        my $pm_found = 0;
+        my $pmpath = join($SLASH, @mod_path_elements).'.pm';
+        my $pm     = $mod_path_elements[-1].'.pm';
+
+        for my $filepath (@{$processable->installed->sorted_list}) {
+            if ($filepath =~ m{\Q$pmpath\E\z|/\Q$pm\E\z}i) {
+                $pm_found = 1;
+                last;
+            }
+        }
+
+        $self->hint('perl-module-name-not-mentioned-in-description', $mod)
+          if (index(lc($extended), $mod_lc) < 0 and $pm_found);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Distribution.pm b/lib/Lintian/Check/Fields/Distribution.pm
new file mode 100644
index 0000000..85390dc
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Distribution.pm
@@ -0,0 +1,167 @@
+# fields/distribution -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software.  It is distributed under the terms of
+# the GNU General Public License as published by the Free Software
+# Foundation; either version 2 of the License, or (at your option) any
+# later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Distribution;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any none);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+
+sub changes {
+    my ($self) = @_;
+
+    my @distributions
+      = $self->processable->fields->trimmed_list('Distribution');
+
+    $self->hint('multiple-distributions-in-changes-file',
+        join($SPACE, @distributions))
+      if @distributions > 1;
+
+    my @targets = grep { $_ ne 'UNRELEASED' } @distributions;
+
+    # Strip common "extensions" for distributions
+    # (except sid and experimental, where they would
+    # make no sense)
+    my %major;
+    for my $target (@targets) {
+
+        my $reduced = $target;
+        $reduced =~ s{- (?:backports(?:-(?:sloppy|staging))?
+                                   |lts
+                                   |proposed(?:-updates)?
+                                   |updates
+                                   |security
+                                   |volatile
+                                   |fasttrack)$}{}xsm;
+
+        $major{$target} = $reduced;
+    }
+
+    my $KNOWN_DISTS = $self->data->load('changes-file/known-dists');
+
+    my @unknown = grep { !$KNOWN_DISTS->recognizes($major{$_}) } @targets;
+    $self->hint('bad-distribution-in-changes-file', $_) for @unknown;
+
+    my @new_version = qw(sid unstable experimental);
+    my $upload_lc = List::Compare->new(\@targets, \@new_version);
+
+    my @regular = $upload_lc->get_intersection;
+    my @special = $upload_lc->get_Lonly;
+
+    # from Parse/DebianChangelog.pm
+    # the changelog entries in the changes file are in a
+    # different format than in the changelog, so the standard
+    # parsers don't work. We just need to know if there is
+    # info for more than 1 entry, so we just copy part of the
+    # parse code here
+    my $changes = $self->processable->fields->value('Changes');
+
+    # count occurrences
+    my @changes_versions
+      = ($changes =~/^(?: \.)?\s*\S+\s+\(([^\(\)]+)\)\s+\S+/mg);
+
+    my $version = $self->processable->fields->value('Version');
+    my $distnumber;
+    my $bpoversion;
+    if ($version=~ /~bpo(\d+)\+(\d+)(\+salsaci(\+\d+)*)?$/) {
+        $distnumber = $1;
+        $bpoversion = $2;
+
+        $self->hint('upload-has-backports-version-number', $version, $_)
+          for @regular;
+    }
+
+    my @backports = grep { /backports/ } @targets;
+    for my $target (@backports) {
+
+        $self->hint('backports-upload-has-incorrect-version-number',
+            $version, $target)
+          if (!defined $distnumber || !defined $bpoversion)
+          || ($major{$target} eq 'squeeze' && $distnumber ne '60')
+          || ($target eq 'wheezy-backports' && $distnumber ne '70')
+          || ($target eq 'wheezy-backports-sloppy' && $distnumber ne '7')
+          || ($major{$target} eq 'jessie' && $distnumber ne '8');
+
+        # for a ~bpoXX+2 or greater version, there
+        # probably will be only a single changelog entry
+        $self->hint('backports-changes-missing')
+          if ($bpoversion // 0) < 2 && @changes_versions == 1;
+    }
+
+    my $first_line = $changes;
+
+    # advance to first non-empty line
+    $first_line =~ s/^\s+//s;
+
+    my $multiple;
+    if ($first_line =~ /^\s*\S+\s+\([^\(\)]+\)([^;]+);/){
+        $multiple = $1;
+    }
+
+    my @changesdists = split($SPACE, $multiple // $EMPTY);
+    return
+      unless @changesdists;
+
+    # issue only when not mentioned in the Distribution field
+    if ((any { $_ eq 'UNRELEASED' } @changesdists)
+        && none { $_ eq 'UNRELEASED' } @distributions) {
+
+        $self->hint('unreleased-changes');
+        return;
+    }
+
+    my $mismatch_lc = List::Compare->new(\@distributions, \@changesdists);
+    my @from_distribution = $mismatch_lc->get_Lonly;
+    my @from_changes = $mismatch_lc->get_Ronly;
+
+    if (@from_distribution || @from_changes) {
+
+        if (any { $_ eq 'experimental' } @from_changes) {
+            $self->hint('distribution-and-experimental-mismatch');
+
+        } else {
+            $self->hint('distribution-and-changes-mismatch',
+                join($SPACE, @from_distribution, @from_changes));
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/DmUploadAllowed.pm b/lib/Lintian/Check/Fields/DmUploadAllowed.pm
new file mode 100644
index 0000000..6670587
--- /dev/null
+++ b/lib/Lintian/Check/Fields/DmUploadAllowed.pm
@@ -0,0 +1,60 @@
+# fields/dm-upload-allowed -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::DmUploadAllowed;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub always {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    return
+      unless $fields->declares('DM-Upload-Allowed');
+
+    $self->hint('dm-upload-allowed-is-obsolete');
+
+    my $dmupload = $fields->unfolded_value('DM-Upload-Allowed');
+
+    $self->hint('malformed-dm-upload-allowed', $dmupload)
+      unless $dmupload eq 'yes';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Empty.pm b/lib/Lintian/Check/Fields/Empty.pm
new file mode 100644
index 0000000..184acd3
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Empty.pm
@@ -0,0 +1,49 @@
+# fields/empty -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Empty;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub always {
+    my ($self) = @_;
+
+    my @all = $self->processable->fields->names;
+    my @empty = grep { !length $self->processable->fields->value($_) } @all;
+
+    $self->hint('empty-field', $_) for @empty;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Essential.pm b/lib/Lintian/Check/Fields/Essential.pm
new file mode 100644
index 0000000..87d43c3
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Essential.pm
@@ -0,0 +1,79 @@
+# fields/essential -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Essential;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    $self->hint('essential-in-source-package')
+      if $fields->declares('Essential');
+
+    return;
+}
+
+sub always {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    return
+      unless $fields->declares('Essential');
+
+    my $essential = $fields->unfolded_value('Essential');
+
+    unless ($essential eq 'yes' || $essential eq 'no') {
+        $self->hint('unknown-essential-value');
+        return;
+    }
+
+    $self->hint('essential-no-not-needed') if $essential eq 'no';
+
+    my $KNOWN_ESSENTIAL = $self->data->load('fields/essential');
+
+    $self->hint('new-essential-package')
+      if $essential eq 'yes'
+      && !$KNOWN_ESSENTIAL->recognizes($self->processable->name);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Format.pm b/lib/Lintian/Check/Fields/Format.pm
new file mode 100644
index 0000000..2d7494a
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Format.pm
@@ -0,0 +1,78 @@
+# fields/format -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Format;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+my @supported_source_formats = (qr/1\.0/, qr/3\.0\s*\((quilt|native)\)/);
+
+sub source {
+    my ($self) = @_;
+
+    return
+      unless $self->processable->fields->declares('Format');
+
+    my $format = $self->processable->fields->unfolded_value('Format');
+
+    my $supported = 0;
+    for my $f (@supported_source_formats){
+
+        $supported = 1
+          if $format =~ /^\s*$f\s*\z/;
+    }
+
+    $self->hint('unsupported-source-format', $format) unless $supported;
+
+    return;
+}
+
+sub changes {
+    my ($self) = @_;
+
+    my $format = $self->processable->fields->unfolded_value('Format');
+
+    # without a Format field something is wrong
+    unless (length $format) {
+        $self->hint('malformed-changes-file');
+        return;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Homepage.pm b/lib/Lintian/Check/Fields/Homepage.pm
new file mode 100644
index 0000000..6e2ae87
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Homepage.pm
@@ -0,0 +1,101 @@
+# fields/homepage -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Homepage;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    return
+      if $self->processable->native;
+
+    my $debian_control = $self->processable->debian_control;
+
+    my @binaries_with_homepage_field
+      = grep { $debian_control->installable_fields($_)->declares('Homepage') }
+      $debian_control->installables;
+
+    if (!$self->processable->fields->declares('Homepage')) {
+
+        $self->hint('homepage-in-binary-package', $_)
+          for @binaries_with_homepage_field;
+    }
+
+    $self->hint('no-homepage-field')
+      unless @binaries_with_homepage_field
+      || $self->processable->fields->declares('Homepage');
+
+    return;
+}
+
+sub always {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    return
+      unless $fields->declares('Homepage');
+
+    my $homepage = $fields->unfolded_value('Homepage');
+
+    my $orig = $fields->value('Homepage');
+
+    if ($homepage =~ /^<(?:UR[LI]:)?.*>$/i) {
+        $self->hint('superfluous-clutter-in-homepage', $orig);
+        $homepage = substr($homepage, 1, length($homepage) - 2);
+    }
+
+    require URI;
+    my $uri = URI->new($homepage);
+
+    # not an absolute URI or (most likely) an invalid protocol
+    $self->hint('bad-homepage', $orig)
+      unless $uri->scheme && $uri->scheme =~ /^(?:ftp|https?|gopher)$/;
+
+    my $BAD_HOMEPAGES = $self->data->load('fields/bad-homepages');
+
+    foreach my $line ($BAD_HOMEPAGES->all) {
+        my ($tag, $re) = split(/\s*~~\s*/, $line);
+        $self->hint($tag, $orig) if $homepage =~ m/$re/;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/InstallerMenuItem.pm b/lib/Lintian/Check/Fields/InstallerMenuItem.pm
new file mode 100644
index 0000000..2b799d3
--- /dev/null
+++ b/lib/Lintian/Check/Fields/InstallerMenuItem.pm
@@ -0,0 +1,59 @@
+# fields/installer-menu-item -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::InstallerMenuItem;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub udeb {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    #---- Installer-Menu-Item (udeb)
+
+    return
+      unless $fields->declares('Installer-Menu-Item');
+
+    my $menu_item = $fields->unfolded_value('Installer-Menu-Item');
+
+    $self->hint('bad-menu-item', $menu_item) unless $menu_item =~ /^\d+$/;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Length.pm b/lib/Lintian/Check/Fields/Length.pm
new file mode 100644
index 0000000..e9765bd
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Length.pm
@@ -0,0 +1,86 @@
+# fields/length -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2019 Sylvestre Ledru
+# Copyright (C) 2019-2020 Chris Lamb <lamby@debian.org>
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Length;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::Compare;
+use List::SomeUtils qw(any);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $MAXIMUM_LENGTH => 5_000;
+
+my @ALLOWED_FIELDS = qw(
+  Build-Ids
+  Description
+  Package-List
+  Installed-Build-Depends
+  Checksums-Sha256
+);
+
+sub always {
+    my ($self) = @_;
+
+    return
+      if any { $self->processable->type eq $_ } qw(changes buildinfo);
+
+    # all fields
+    my @all = $self->processable->fields->names;
+
+    # longer than maximum
+    my @long= grep {
+        length $self->processable->fields->untrimmed_value($_)> $MAXIMUM_LENGTH
+    }@all;
+
+    # filter allowed fields
+    my $allowedlc = List::Compare->new(\@long, \@ALLOWED_FIELDS);
+    my @too_long = $allowedlc->get_Lonly;
+
+    for my $name (@too_long) {
+
+        my $length = length $self->processable->fields->value($name);
+
+        $self->hint('field-too-long', $name,
+            "($length chars > $MAXIMUM_LENGTH)");
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/MailAddress.pm b/lib/Lintian/Check/Fields/MailAddress.pm
new file mode 100644
index 0000000..02fd5f1
--- /dev/null
+++ b/lib/Lintian/Check/Fields/MailAddress.pm
@@ -0,0 +1,150 @@
+# fields/mail-address -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Felix Lechner
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::MailAddress;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Data::Validate::Domain;
+use Email::Address::XS;
+use List::SomeUtils qw(any all);
+use List::UtilsBy qw(uniq_by);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $QA_GROUP_PHRASE => 'Debian QA Group';
+const my $QA_GROUP_ADDRESS => 'packages@qa.debian.org';
+const my $ARROW => q{ -> };
+
+# list of addresses known to bounce messages from role accounts
+my @KNOWN_BOUNCE_ADDRESSES = qw(
+  ubuntu-devel-discuss@lists.ubuntu.com
+);
+
+sub always {
+    my ($self) = @_;
+
+    my @singles = qw(Maintainer Changed-By);
+    my @groups = qw(Uploaders);
+
+    my @singles_present
+      = grep { $self->processable->fields->declares($_) } @singles;
+    my @groups_present
+      = grep { $self->processable->fields->declares($_) } @groups;
+
+    my %parsed;
+    for my $role (@singles_present, @groups_present) {
+
+        my $value = $self->processable->fields->value($role);
+        $parsed{$role} = [Email::Address::XS->parse($value)];
+    }
+
+    for my $role (keys %parsed) {
+
+        my @invalid = grep { !$_->is_valid } @{$parsed{$role}};
+        $self->hint('malformed-contact', $role, $_->original)for @invalid;
+
+        my @valid = grep { $_->is_valid } @{$parsed{$role}};
+        my @unique = uniq_by { $_->format } @valid;
+
+        $self->check_single_address($role, $_) for @unique;
+    }
+
+    for my $role (@singles_present) {
+        $self->hint('too-many-contacts', $role,
+            $self->processable->fields->value($role))
+          if @{$parsed{$role}} > 1;
+    }
+
+    for my $role (@groups_present) {
+        my @valid = grep { $_->is_valid } @{$parsed{$role}};
+        my @addresses = map { $_->address } @valid;
+
+        my %count;
+        $count{$_}++ for @addresses;
+        my @duplicates = grep { $count{$_} > 1 } keys %count;
+
+        $self->hint('duplicate-contact', $role, $_) for @duplicates;
+    }
+
+    return;
+}
+
+sub check_single_address {
+    my ($self, $role, $parsed) = @_;
+
+    $self->hint('mail-contact', $role, $parsed->format);
+
+    unless (all { length } ($parsed->address, $parsed->user, $parsed->host)) {
+        $self->hint('incomplete-mail-address', $role, $parsed->format);
+        return;
+    }
+
+    $self->hint('bogus-mail-host', $role, $parsed->address)
+      unless is_domain($parsed->host, {domain_disable_tld_validation => 1});
+
+    $self->hint('mail-address-loops-or-bounces',$role, $parsed->address)
+      if any { $_ eq $parsed->address } @KNOWN_BOUNCE_ADDRESSES;
+
+    unless (length $parsed->phrase) {
+        $self->hint('no-phrase', $role, $parsed->format);
+        return;
+    }
+
+    $self->hint('root-in-contact', $role, $parsed->format)
+      if $parsed->user eq 'root' || $parsed->phrase eq 'root';
+
+    # Debian QA Group
+    $self->hint('faulty-debian-qa-group-phrase',
+        $role, $parsed->phrase . $ARROW . $QA_GROUP_PHRASE)
+      if $parsed->address eq $QA_GROUP_ADDRESS
+      && $parsed->phrase ne $QA_GROUP_PHRASE;
+
+    $self->hint('faulty-debian-qa-group-address',
+        $role, $parsed->address . $ARROW . $QA_GROUP_ADDRESS)
+      if ( $parsed->phrase =~ /\bdebian\s+qa\b/i
+        && $parsed->address ne $QA_GROUP_ADDRESS)
+      || $parsed->address eq 'debian-qa@lists.debian.org';
+
+    $self->hint('mailing-list-on-alioth', $role, $parsed->address)
+      if $parsed->host eq 'lists.alioth.debian.org';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Maintainer.pm b/lib/Lintian/Check/Fields/Maintainer.pm
new file mode 100644
index 0000000..7267092
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Maintainer.pm
@@ -0,0 +1,84 @@
+# fields/maintainer -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Felix Lechner
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Maintainer;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    return
+      unless $self->processable->fields->declares('Maintainer');
+
+    my $maintainer = $self->processable->fields->value('Maintainer');
+
+    my $is_list = $maintainer =~ /\@lists(?:\.alioth)?\.debian\.org\b/;
+
+    $self->hint('no-human-maintainers')
+      if $is_list && !$self->processable->fields->declares('Uploaders');
+
+    return;
+}
+
+sub changes {
+    my ($self) = @_;
+
+    my $source = $self->group->source;
+    return
+      unless defined $source;
+
+    my $changes_maintainer = $self->processable->fields->value('Maintainer');
+    my $changes_distribution
+      = $self->processable->fields->value('Distribution');
+
+    my $source_maintainer = $source->fields->value('Maintainer');
+
+    my $KNOWN_DISTS = $self->data->load('changes-file/known-dists');
+
+    # not for derivatives; https://wiki.ubuntu.com/DebianMaintainerField
+    $self->hint('inconsistent-maintainer',
+        $changes_maintainer . ' (changes vs. source) ' .$source_maintainer)
+      if $changes_maintainer ne $source_maintainer
+      && $KNOWN_DISTS->recognizes($changes_distribution);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Maintainer/Team.pm b/lib/Lintian/Check/Fields/Maintainer/Team.pm
new file mode 100644
index 0000000..b068d9f
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Maintainer/Team.pm
@@ -0,0 +1,90 @@
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Maintainer::Team;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Email::Address::XS;
+use List::SomeUtils qw(uniq first_value);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $ARROW => qq{ \N{RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK} };
+
+my %team_names = (
+    'debian-go@lists.debian.org' => 'golang',
+    'debian-clojure@lists.debian.org' => 'clojure',
+    'pkg-java-maintainers@lists.alioth.debian.org' => 'java',
+    'pkg-javascript-maintainers@lists.alioth.debian.org' => 'javascript',
+    'pkg-perl-maintainers@lists.alioth.debian.org' => 'perl',
+    'team+python@tracker.debian.org' => 'python'
+);
+
+sub source {
+    my ($self) = @_;
+
+    my $maintainer = $self->processable->fields->value('Maintainer');
+    return
+      unless length $maintainer;
+
+    my $parsed = Email::Address::XS->parse($maintainer);
+    return
+      unless $parsed->is_valid;
+
+    return
+      unless length $parsed->address;
+
+    my $team = $team_names{$parsed->address};
+    return
+      unless length $team;
+
+    return
+      if $self->name_contains($team);
+
+    my @other_teams = uniq grep { $_ ne $team } values %team_names;
+
+    my $name_suggests = first_value { $self->name_contains($_) } @other_teams;
+    return
+      unless length $name_suggests;
+
+    $self->hint('wrong-team', $team . $ARROW . $name_suggests)
+      unless $name_suggests eq $team;
+
+    return;
+}
+
+sub name_contains {
+    my ($self, $string) = @_;
+
+    return $self->processable->name =~ m{ \b \Q$string\E \b }sx;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/MultiArch.pm b/lib/Lintian/Check/Fields/MultiArch.pm
new file mode 100644
index 0000000..5b42f9f
--- /dev/null
+++ b/lib/Lintian/Check/Fields/MultiArch.pm
@@ -0,0 +1,138 @@
+# fields/multi-arch -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::MultiArch;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(uniq any);
+use Unicode::UTF8 qw(decode_utf8);
+
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SPACE => q{ };
+
+sub source {
+    my ($self) = @_;
+
+    my $pkg = $self->processable->name;
+    my $processable = $self->processable;
+
+    for my $bin ($processable->debian_control->installables) {
+
+        next
+          unless ($processable->debian_control->installable_fields($bin)
+            ->value('Multi-Arch')) eq 'same';
+
+        my $wildcard = $processable->debian_control->installable_fields($bin)
+          ->value('Architecture');
+        my @arches   = split(
+            $SPACE,
+            decode_utf8(
+                safe_qx(
+                    'dpkg-architecture', '--match-wildcard',
+                    $wildcard,           '--list-known'
+                )
+            )
+        );
+
+        # include original wildcard
+        push(@arches, $wildcard);
+
+        for my $port (uniq @arches) {
+
+            my $specific = $processable->patched->resolve_path(
+                "debian/$bin.lintian-overrides.$port");
+            next
+              unless defined $specific;
+
+            $self->pointed_hint(
+                'multi-arch-same-package-has-arch-specific-overrides',
+                $specific->pointer);
+        }
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    if ($self->processable->name =~ /^x?fonts-/) {
+
+        my $multi = $fields->value('Multi-Arch') || 'no';
+
+        $self->hint('font-package-not-multi-arch-foreign')
+          unless any { $multi eq $_ } qw(foreign allowed);
+    }
+
+    return
+      unless $fields->declares('Multi-Arch');
+
+    my $multi = $fields->unfolded_value('Multi-Arch');
+
+    if ($fields->declares('Architecture')) {
+
+        my $architecture = $fields->unfolded_value('Architecture');
+
+        $self->hint('illegal-multi-arch-value', $architecture, $multi)
+          if $architecture eq 'all' && $multi eq 'same';
+    }
+
+    return;
+}
+
+sub always {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    return
+      unless $fields->declares('Multi-Arch');
+
+    my $multi = $fields->unfolded_value('Multi-Arch');
+
+    $self->hint('unknown-multi-arch-value', $self->processable->name, $multi)
+      unless any { $multi eq $_ } qw(no foreign allowed same);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/MultiLine.pm b/lib/Lintian/Check/Fields/MultiLine.pm
new file mode 100644
index 0000000..ca31cd5
--- /dev/null
+++ b/lib/Lintian/Check/Fields/MultiLine.pm
@@ -0,0 +1,89 @@
+# fields/multi-line -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2019 Felix Lechner
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::MultiLine;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::Compare;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $NEWLINE => qq{\n};
+
+# based on policy 5.6
+my @always_single = (
+    qw(Architecture Bugs Changed-By Closes Date Distribution Dm-Upload-Allowed),
+    qw(Essential Format Homepage Installed-Size Installer-Menu-Item Maintainer),
+    qw(Multi-Arch Origin Package Priority Section Source Standards-Version),
+    qw(Subarchitecture Urgency Version)
+);
+
+my @package_relations
+  = (
+    qw(Depends Pre-Depends Recommends Suggests Conflicts Provides Enhances Replaces Breaks)
+  );
+
+sub always {
+    my ($self) = @_;
+
+    my @banned = @always_single;
+
+    # for package relations, multi-line only in source (policy 7.1)
+    push(@banned, @package_relations)
+      unless $self->processable->type eq 'source';
+
+    my @present = $self->processable->fields->names;
+
+    my $single_lc = List::Compare->new(\@present, \@banned);
+    my @enforce = $single_lc->get_intersection;
+
+    for my $name (@enforce) {
+
+        my $value = $self->processable->fields->untrimmed_value($name);
+
+        # remove a final newline, if any
+        $value =~ s/\n$//;
+
+        # check if fields have newlines in them
+        $self->hint('multiline-field', $name)
+          if index($value, $NEWLINE) >= 0;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Origin.pm b/lib/Lintian/Check/Fields/Origin.pm
new file mode 100644
index 0000000..4d36793
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Origin.pm
@@ -0,0 +1,57 @@
+# fields/origin -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Origin;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub always {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    return
+      unless $fields->declares('Origin');
+
+    my $origin = $fields->unfolded_value('Origin');
+
+    $self->hint('redundant-origin-field') if lc($origin) eq 'debian';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Package.pm b/lib/Lintian/Check/Fields/Package.pm
new file mode 100644
index 0000000..2ce436f
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Package.pm
@@ -0,0 +1,61 @@
+# fields/package -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Package;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::Util qw($PKGNAME_REGEX);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub installable {
+    my ($self) = @_;
+
+    return
+      unless $self->processable->fields->declares('Package');
+
+    my $name = $self->processable->fields->unfolded_value('Package');
+
+    $self->hint('bad-package-name') unless $name =~ /^$PKGNAME_REGEX$/i;
+
+    $self->hint('package-not-lowercase') if $name =~ /[A-Z]/;
+
+    $self->hint('unusual-documentation-package-name') if $name =~ /-docs$/;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/PackageRelations.pm b/lib/Lintian/Check/Fields/PackageRelations.pm
new file mode 100644
index 0000000..eeb11c0
--- /dev/null
+++ b/lib/Lintian/Check/Fields/PackageRelations.pm
@@ -0,0 +1,794 @@
+# fields/package-relations -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2019-2020 Chris Lamb <lamby@debian.org>
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::PackageRelations;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Dpkg::Version qw(version_check);
+use List::SomeUtils qw(any);
+
+use Lintian::Relation;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $EQUAL => q{=};
+const my $VERTICAL_BAR => q{|};
+
+# Still in the archive but shouldn't be the primary Emacs dependency.
+my @obsolete_emacs_versions = qw(21 22 23);
+my @emacs_flavors = ($EMPTY, qw(-el -gtk -nox -lucid));
+my %known_obsolete_emacs;
+for my $version (@obsolete_emacs_versions) {
+    for my $flavor (@emacs_flavors) {
+
+        my $package = 'emacs' . $version . $flavor;
+        $known_obsolete_emacs{$package} = 1;
+    }
+}
+
+my %known_libstdcs = map { $_ => 1 } qw(
+  libstdc++2.9-glibc2.1
+  libstdc++2.10
+  libstdc++2.10-glibc2.2
+  libstdc++3
+  libstdc++3.0
+  libstdc++4
+  libstdc++5
+  libstdc++6
+  lib64stdc++6
+);
+
+my %known_tcls = map { $_ => 1 } qw(
+  tcl74
+  tcl8.0
+  tcl8.2
+  tcl8.3
+  tcl8.4
+  tcl8.5
+);
+
+my %known_tclxs = map { $_ => 1 } qw(
+  tclx76
+  tclx8.0.4
+  tclx8.2
+  tclx8.3
+  tclx8.4
+);
+
+my %known_tks = map { $_ => 1 } qw(
+  tk40
+  tk8.0
+  tk8.2
+  tk8.3
+  tk8.4
+  tk8.5
+);
+
+my %known_libpngs = map { $_ => 1 } qw(
+  libpng12-0
+  libpng2
+  libpng3
+);
+
+my @known_java_pkg = map { qr/$_/ } (
+    'default-j(?:re|dk)(?:-headless)?',
+    # java-runtime and javaX-runtime alternatives (virtual)
+    'java\d*-runtime(?:-headless)?',
+    # openjdk-X and sun-javaX
+    '(openjdk-|sun-java)\d+-j(?:re|dk)(?:-headless)?',
+    'gcj-(?:\d+\.\d+-)?jre(?:-headless)?', 'gcj-(?:\d+\.\d+-)?jdk', # gcj
+    'gij',
+    'java-gcj-compat(?:-dev|-headless)?', # deprecated/transitional packages
+    'kaffe', 'cacao', 'jamvm',
+    'classpath', # deprecated packages (removed in Squeeze)
+);
+
+# Python development packages that are used almost always just for building
+# architecture-dependent modules.  Used to check for unnecessary build
+# dependencies for architecture-independent source packages.
+our $PYTHON_DEV = join(' | ',
+    qw(python3-dev python3-all-dev),
+    map { "python$_-dev:any" } qw(2.7 3 3.7 3.8 3.9));
+
+sub installable {
+    my ($self) = @_;
+
+    my $pkg = $self->processable->name;
+    my $type = $self->processable->type;
+    my $processable = $self->processable;
+    my $group = $self->group;
+
+    my $KNOWN_ESSENTIAL = $self->data->load('fields/essential');
+    my $KNOWN_TOOLCHAIN = $self->data->load('fields/toolchain');
+    my $KNOWN_METAPACKAGES = $self->data->load('fields/metapackages');
+
+    my $DH_ADDONS = $self->data->debhelper_addons;
+    my %DH_ADDONS_VALUES
+      = map { $_ => 1 } map { $DH_ADDONS->installed_by($_) } $DH_ADDONS->all;
+
+    my $OBSOLETE_PACKAGES
+      = $self->data->load('fields/obsolete-packages',qr/\s*=>\s*/);
+
+    my $VIRTUAL_PACKAGES= $self->data->load('fields/virtual-packages');
+
+    my $javalib = 0;
+    my $replaces = $processable->relation('Replaces');
+    my %nag_once;
+    $javalib = 1 if($pkg =~ m/^lib.*-java$/);
+    for my $field (
+        qw(Depends Pre-Depends Recommends Suggests Conflicts Provides Enhances Replaces Breaks)
+    ) {
+        next
+          unless $processable->fields->declares($field);
+
+        # get data and clean it
+        my $data = $processable->fields->unfolded_value($field);
+        my $javadep = 0;
+
+        my (@seen_libstdcs, @seen_tcls, @seen_tclxs,@seen_tks, @seen_libpngs);
+
+        my $is_dep_field
+          = any { $field eq $_ } qw(Depends Pre-Depends Recommends Suggests);
+
+        $self->hint('alternates-not-allowed', $field)
+          if ($data =~ /\|/ && !$is_dep_field);
+        $self->check_field($field, $data) if $is_dep_field;
+
+        for my $dep (split /\s*,\s*/, $data) {
+            my (@alternatives, @seen_obsolete_packages);
+            push @alternatives, [_split_dep($_), $_]
+              for (split /\s*\|\s*/, $dep);
+
+            if ($is_dep_field) {
+                push @seen_libstdcs, $alternatives[0][0]
+                  if defined $known_libstdcs{$alternatives[0][0]};
+                push @seen_tcls, $alternatives[0][0]
+                  if defined $known_tcls{$alternatives[0][0]};
+                push @seen_tclxs, $alternatives[0][0]
+                  if defined $known_tclxs{$alternatives[0][0]};
+                push @seen_tks, $alternatives[0][0]
+                  if defined $known_tks{$alternatives[0][0]};
+                push @seen_libpngs, $alternatives[0][0]
+                  if defined $known_libpngs{$alternatives[0][0]};
+            }
+
+            # Only for (Pre-)?Depends.
+            $self->hint('virtual-package-depends-without-real-package-depends',
+                "$field: $alternatives[0][0]")
+              if (
+                $VIRTUAL_PACKAGES->recognizes($alternatives[0][0])
+                && ($field eq 'Depends' || $field eq 'Pre-Depends')
+                && ($pkg ne 'base-files' || $alternatives[0][0] ne 'awk')
+                # ignore phpapi- dependencies as adding an
+                # alternative, real, package breaks its purpose
+                && $alternatives[0][0] !~ m/^phpapi-/
+              );
+
+            # Check defaults for transitions.  Here, we only care
+            # that the first alternative is current.
+            $self->hint('depends-on-old-emacs', "$field: $alternatives[0][0]")
+              if ( $is_dep_field
+                && $known_obsolete_emacs{$alternatives[0][0]});
+
+            for my $part_d (@alternatives) {
+                my ($d_pkg, $d_march, $d_version, undef, undef, $rest,
+                    $part_d_orig)
+                  = @{$part_d};
+
+                $self->hint('invalid-versioned-provides', $part_d_orig)
+                  if ( $field eq 'Provides'
+                    && $d_version->[0]
+                    && $d_version->[0] ne $EQUAL);
+
+                $self->hint('bad-provided-package-name', $d_pkg)
+                  if $d_pkg !~ /^[a-z0-9][-+\.a-z0-9]+$/;
+
+                $self->hint('breaks-without-version', $part_d_orig)
+                  if ( $field eq 'Breaks'
+                    && !$d_version->[0]
+                    && !$VIRTUAL_PACKAGES->recognizes($d_pkg)
+                    && !$replaces->satisfies($part_d_orig));
+
+                $self->hint('conflicts-with-version', $part_d_orig)
+                  if ($field eq 'Conflicts' && $d_version->[0]);
+
+                $self->hint('obsolete-relation-form', "$field: $part_d_orig")
+                  if ($d_version && any { $d_version->[0] eq $_ }('<', '>'));
+
+                $self->hint('bad-version-in-relation', "$field: $part_d_orig")
+                  if ($d_version->[0] && !version_check($d_version->[1]));
+
+                $self->hint('package-relation-with-self',
+                    "$field: $part_d_orig")
+                  if ($pkg eq $d_pkg)
+                  && (!$d_march)
+                  && ( $field ne 'Conflicts'
+                    && $field ne 'Replaces'
+                    && $field ne 'Provides');
+
+                $self->hint('bad-relation', "$field: $part_d_orig") if $rest;
+
+                push @seen_obsolete_packages, [$part_d_orig, $d_pkg]
+                  if ( $OBSOLETE_PACKAGES->recognizes($d_pkg)
+                    && $is_dep_field);
+
+                $self->hint('depends-on-metapackage', "$field: $part_d_orig")
+                  if ( $KNOWN_METAPACKAGES->recognizes($d_pkg)
+                    && !$KNOWN_METAPACKAGES->recognizes($pkg)
+                    && !$processable->is_transitional
+                    && !$processable->is_meta_package
+                    && $is_dep_field);
+
+                # diffutils is a special case since diff was
+                # renamed to diffutils, so a dependency on
+                # diffutils effectively is a versioned one.
+                $self->hint(
+                    'depends-on-essential-package-without-using-version',
+                    "$field: $part_d_orig")
+                  if ( $KNOWN_ESSENTIAL->recognizes($d_pkg)
+                    && !$d_version->[0]
+                    && $is_dep_field
+                    && $d_pkg ne 'diffutils'
+                    && $d_pkg ne 'dash');
+
+                $self->hint('package-depends-on-an-x-font-package',
+                    "$field: $part_d_orig")
+                  if ( $field =~ /^(?:Pre-)?Depends$/
+                    && $d_pkg =~ /^xfont.*/
+                    && $d_pkg ne 'xfonts-utils'
+                    && $d_pkg ne 'xfonts-encodings');
+
+                $self->hint('depends-on-packaging-dev',$field)
+                  if (($field =~ /^(?:Pre-)?Depends$/|| $field eq 'Recommends')
+                    && $d_pkg eq 'packaging-dev'
+                    && !$processable->is_transitional
+                    && !$processable->is_meta_package);
+
+                $self->hint('needless-suggest-recommend-libservlet-java',
+                    "$d_pkg")
+                  if (($field eq 'Recommends' || $field eq 'Suggests')
+                    && $d_pkg =~ m/libservlet[\d\.]+-java/);
+
+                $self->hint('needlessly-depends-on-awk', $field)
+                  if ( $d_pkg eq 'awk'
+                    && !$d_version->[0]
+                    && $is_dep_field
+                    && $pkg ne 'base-files');
+
+                $self->hint('depends-on-libdb1-compat', $field)
+                  if ( $d_pkg eq 'libdb1-compat'
+                    && $pkg !~ /^libc(?:6|6.1|0.3)/
+                    && $field =~ /^(?:Pre-)?Depends$/);
+
+                $self->hint('depends-on-python-minimal', $field,)
+                  if ( $d_pkg =~ /^python[\d.]*-minimal$/
+                    && $is_dep_field
+                    && $pkg !~ /^python[\d.]*-minimal$/);
+
+                $self->hint('doc-package-depends-on-main-package', $field)
+                  if ("$d_pkg-doc" eq $pkg
+                    && $field =~ /^(?:Pre-)?Depends$/);
+
+                $self->hint(
+                    'package-relation-with-perl-modules', "$field: $d_pkg"
+                      # matches "perl-modules" (<= 5.20) as well as
+                      # perl-modules-5.xx (>> 5.20)
+                  )
+                  if $d_pkg =~ /^perl-modules/
+                  && $field ne 'Replaces'
+                  && $processable->source_name ne 'perl';
+
+                $self->hint('depends-exclusively-on-makedev', $field,)
+                  if ( $field eq 'Depends'
+                    && $d_pkg eq 'makedev'
+                    && @alternatives == 1);
+
+                $self->hint('lib-recommends-documentation',
+                    "$field: $part_d_orig")
+                  if ( $field eq 'Recommends'
+                    && $pkg =~ m/^lib/
+                    && $pkg !~ m/-(?:dev|docs?|tools|bin)$/
+                    && $part_d_orig =~ m/-docs?$/);
+
+                $self->hint('binary-package-depends-on-toolchain-package',
+                    "$field: $part_d_orig")
+                  if $KNOWN_TOOLCHAIN->recognizes($d_pkg)
+                  && $is_dep_field
+                  && $pkg !~ /^dh-/
+                  && $pkg !~ /-(?:source|src)$/
+                  && !$processable->is_transitional
+                  && !$processable->is_meta_package
+                  && !$DH_ADDONS_VALUES{$pkg};
+
+                # default-jdk-doc must depend on openjdk-X-doc (or
+                # classpath-doc) to be useful; other packages
+                # should depend on default-jdk-doc if they want
+                # the Java Core API.
+                $self->hint('depends-on-specific-java-doc-package',$field)
+                  if (
+                    $is_dep_field
+                    && $pkg ne 'default-jdk-doc'
+                    && (   $d_pkg eq 'classpath-doc'
+                        || $d_pkg =~ /openjdk-\d+-doc/)
+                  );
+
+                if ($javalib && $field eq 'Depends'){
+                    foreach my $reg (@known_java_pkg){
+                        if($d_pkg =~ m/$reg/){
+                            $javadep++;
+                            last;
+                        }
+
+                    }
+                }
+            }
+
+            for my $d (@seen_obsolete_packages) {
+                my ($dep, $pkg_name) = @{$d};
+                my $replacement = $OBSOLETE_PACKAGES->value($pkg_name)
+                  // $EMPTY;
+                $replacement = ' => ' . $replacement
+                  if $replacement ne $EMPTY;
+                if ($pkg_name eq $alternatives[0][0]
+                    or scalar @seen_obsolete_packages== scalar @alternatives) {
+                    $self->hint(
+                        'depends-on-obsolete-package',
+                        "$field: $dep${replacement}"
+                    );
+                } else {
+                    $self->hint(
+                        'ored-depends-on-obsolete-package',
+                        "$field: $dep${replacement}"
+                    );
+                }
+            }
+
+            # Only emit the tag if all the alternatives are
+            # JVM/JRE/JDKs
+            # - assume that <some-lib> | openjdk-X-jre-headless
+            #   makes sense for now.
+            if (scalar(@alternatives) == $javadep
+                && !exists $nag_once{'needless-dependency-on-jre'}){
+                $nag_once{'needless-dependency-on-jre'} = 1;
+                $self->hint('needless-dependency-on-jre');
+            }
+        }
+        $self->hint('package-depends-on-multiple-libstdc-versions',
+            @seen_libstdcs)
+          if (scalar @seen_libstdcs > 1);
+        $self->hint('package-depends-on-multiple-tcl-versions', @seen_tcls)
+          if (scalar @seen_tcls > 1);
+        $self->hint('package-depends-on-multiple-tclx-versions', @seen_tclxs)
+          if (scalar @seen_tclxs > 1);
+        $self->hint('package-depends-on-multiple-tk-versions', @seen_tks)
+          if (scalar @seen_tks > 1);
+        $self->hint('package-depends-on-multiple-libpng-versions',
+            @seen_libpngs)
+          if (scalar @seen_libpngs > 1);
+    }
+
+    # If Conflicts or Breaks is set, make sure it's not inconsistent with
+    # the other dependency fields.
+    for my $conflict (qw/Conflicts Breaks/) {
+        next
+          unless $processable->fields->declares($conflict);
+
+        for my $field (qw(Depends Pre-Depends Recommends Suggests)) {
+            next
+              unless $processable->fields->declares($field);
+
+            my $relation = $processable->relation($field);
+            for my $package (split /\s*,\s*/,
+                $processable->fields->value($conflict)) {
+
+                $self->hint('conflicts-with-dependency', $field, $package)
+                  if $relation->satisfies($package);
+            }
+        }
+    }
+
+    return;
+}
+
+sub source {
+    my ($self) = @_;
+
+    my $pkg = $self->processable->name;
+    my $type = $self->processable->type;
+    my $processable = $self->processable;
+    my $group = $self->group;
+
+    my $KNOWN_ESSENTIAL = $self->data->load('fields/essential');
+    my $KNOWN_METAPACKAGES = $self->data->load('fields/metapackages');
+    my $NO_BUILD_DEPENDS= $self->data->load('fields/no-build-depends');
+    my $known_build_essential
+      = $self->data->load('fields/build-essential-packages');
+    my $KNOWN_BUILD_PROFILES= $self->data->load('fields/build-profiles');
+
+    my $OBSOLETE_PACKAGES
+      = $self->data->load('fields/obsolete-packages',qr/\s*=>\s*/);
+
+    my $VIRTUAL_PACKAGES= $self->data->load('fields/virtual-packages');
+
+    my @binpkgs = $processable->debian_control->installables;
+
+    #Get number of arch-indep packages:
+    my $arch_indep_packages = 0;
+    my $arch_dep_packages = 0;
+
+    for my $binpkg (@binpkgs) {
+        my $arch = $processable->debian_control->installable_fields($binpkg)
+          ->value('Architecture');
+
+        if ($arch eq 'all') {
+            $arch_indep_packages++;
+        } else {
+            $arch_dep_packages++;
+        }
+    }
+
+    $self->hint('build-depends-indep-without-arch-indep')
+      if ( $processable->fields->declares('Build-Depends-Indep')
+        && $arch_indep_packages == 0);
+
+    $self->hint('build-depends-arch-without-arch-dependent-binary')
+      if ( $processable->fields->declares('Build-Depends-Arch')
+        && $arch_dep_packages == 0);
+
+    my %depend;
+    for my $field (
+        qw(Build-Depends Build-Depends-Indep Build-Depends-Arch Build-Conflicts Build-Conflicts-Indep Build-Conflicts-Arch)
+    ) {
+        if ($processable->fields->declares($field)) {
+
+            my $is_dep_field = any { $field eq $_ }
+              qw(Build-Depends Build-Depends-Indep Build-Depends-Arch);
+
+            # get data and clean it
+            my $data = $processable->fields->unfolded_value($field);
+
+            $self->check_field($field, $data);
+            $depend{$field} = $data;
+
+            for my $dep (split /\s*,\s*/, $data) {
+                my (@alternatives, @seen_obsolete_packages);
+                push @alternatives, [_split_dep($_), $_]
+                  for (split /\s*\|\s*/, $dep);
+
+                $self->hint(
+                    'virtual-package-depends-without-real-package-depends',
+                    "$field: $alternatives[0][0]")
+                  if ( $VIRTUAL_PACKAGES->recognizes($alternatives[0][0])
+                    && $is_dep_field);
+
+                for my $part_d (@alternatives) {
+                    my ($d_pkg, undef, $d_version, $d_arch, $d_restr,
+                        $rest,$part_d_orig)
+                      = @{$part_d};
+
+                    for my $arch (@{$d_arch->[0]}) {
+                        $self->hint('invalid-arch-string-in-source-relation',
+                            $arch, "[$field: $part_d_orig]")
+                          if $arch eq 'all'
+                          || (
+                            !$self->data->architectures
+                            ->is_release_architecture(
+                                $arch)
+                            && !$self->data->architectures->is_wildcard($arch)
+                          );
+                    }
+
+                    for my $restrlist (@{$d_restr}) {
+                        for my $prof (@{$restrlist}) {
+                            $prof =~ s/^!//;
+                            $self->hint(
+                                'invalid-profile-name-in-source-relation',
+                                "$prof [$field: $part_d_orig]"
+                              )
+                              unless $KNOWN_BUILD_PROFILES->recognizes($prof)
+                              or $prof =~ /^pkg\.[a-z0-9][a-z0-9+.-]+\../;
+                        }
+                    }
+
+                    if (   $d_pkg =~ /^openjdk-\d+-doc$/
+                        or $d_pkg eq 'classpath-doc'){
+                        $self->hint(
+                            'build-depends-on-specific-java-doc-package',
+                            $d_pkg);
+                    }
+
+                    if ($d_pkg eq 'java-compiler'){
+                        $self->hint(
+                            'build-depends-on-an-obsolete-java-package',
+                            $d_pkg);
+                    }
+
+                    if (    $d_pkg =~ /^libdb\d+\.\d+.*-dev$/
+                        and $is_dep_field) {
+                        $self->hint('build-depends-on-versioned-berkeley-db',
+                            "$field:$d_pkg");
+                    }
+
+                    $self->hint('conflicting-negation-in-source-relation',
+                        "$field: $part_d_orig")
+                      if ( $d_arch
+                        && $d_arch->[1] != 0
+                        && $d_arch->[1] ne @{ $d_arch->[0] });
+
+                    $self->hint('depends-on-packaging-dev', $field)
+                      if ($d_pkg eq 'packaging-dev');
+
+                    $self->hint('build-depends-on-build-essential', $field)
+                      if ($d_pkg eq 'build-essential');
+
+                    $self->hint(
+'build-depends-on-build-essential-package-without-using-version',
+                        "$d_pkg [$field: $part_d_orig]"
+                      )
+                      if ($known_build_essential->recognizes($d_pkg)
+                        && !$d_version->[1]);
+
+                    $self->hint(
+'build-depends-on-essential-package-without-using-version',
+                        "$field: $part_d_orig"
+                      )
+                      if ( $KNOWN_ESSENTIAL->recognizes($d_pkg)
+                        && !$d_version->[0]
+                        && $d_pkg ne 'dash');
+                    push @seen_obsolete_packages, [$part_d_orig, $d_pkg]
+                      if ( $OBSOLETE_PACKAGES->recognizes($d_pkg)
+                        && $is_dep_field);
+
+                    $self->hint('build-depends-on-metapackage',
+                        "$field: $part_d_orig")
+                      if (  $KNOWN_METAPACKAGES->recognizes($d_pkg)
+                        and $is_dep_field);
+
+                    $self->hint('build-depends-on-non-build-package',
+                        "$field: $part_d_orig")
+                      if (  $NO_BUILD_DEPENDS->recognizes($d_pkg)
+                        and $is_dep_field);
+
+                    $self->hint('build-depends-on-1-revision',
+                        "$field: $part_d_orig")
+                      if ( $d_version->[0] eq '>='
+                        && $d_version->[1] =~ /-1$/
+                        && $is_dep_field);
+
+                    $self->hint('bad-relation', "$field: $part_d_orig")
+                      if $rest;
+
+                    $self->hint('bad-version-in-relation',
+                        "$field: $part_d_orig")
+                      if ($d_version->[0]
+                        && !version_check($d_version->[1]));
+
+                    $self->hint(
+                        'package-relation-with-perl-modules',
+                        "$field: $part_d_orig"
+                          # matches "perl-modules" (<= 5.20) as well as
+                          # perl-modules-5.xx (>> 5.20)
+                      )
+                      if $d_pkg =~ /^perl-modules/
+                      && $processable->source_name ne 'perl';
+                }
+
+                my $all_obsolete = 0;
+                $all_obsolete = 1
+                  if scalar @seen_obsolete_packages == @alternatives;
+                for my $d (@seen_obsolete_packages) {
+                    my ($dep, $pkg_name) = @{$d};
+                    my $replacement = $OBSOLETE_PACKAGES->value($pkg_name)
+                      // $EMPTY;
+
+                    $replacement = ' => ' . $replacement
+                      if $replacement ne $EMPTY;
+                    if (   $pkg_name eq $alternatives[0][0]
+                        or $all_obsolete) {
+                        $self->hint('build-depends-on-obsolete-package',
+                            "$field: $dep${replacement}");
+                    } else {
+                        $self->hint('ored-build-depends-on-obsolete-package',
+                            "$field: $dep${replacement}");
+                    }
+                }
+            }
+        }
+    }
+
+    # Check for redundancies.
+    my @to_check = (
+        ['Build-Depends'],
+        ['Build-Depends', 'Build-Depends-Indep'],
+        ['Build-Depends', 'Build-Depends-Arch']
+    );
+
+    for my $fields (@to_check) {
+        my $relation = Lintian::Relation->new->logical_and(
+            map { $processable->relation($_) }@{$fields});
+
+        for my $redundant_set ($relation->redundancies) {
+
+            $self->hint(
+                'redundant-build-prerequisites',
+                join(', ', sort @{$redundant_set})
+            );
+        }
+    }
+
+    # Make sure build dependencies and conflicts are consistent.
+    my $build_all = $processable->relation('Build-Depends-All');
+
+    for my $field (
+        qw{Build-Conflicts Build-Conflicts-Indep Build-Conflicts-Arch}) {
+
+        my @conflicts= $processable->fields->trimmed_list($field, qr{\s*,\s*});
+        my @contradictions = grep { $build_all->satisfies($_) } @conflicts;
+
+        my $position = $processable->fields->position($field);
+        my $pointer = $processable->debian_control->item->pointer($position);
+
+        $self->pointed_hint('build-conflicts-with-build-dependency',
+            $pointer, $field, $_)
+          for @contradictions;
+    }
+
+    my (@arch_dep_pkgs, @dbg_pkgs);
+    for my $installable ($group->get_installables) {
+
+        if ($installable->name =~ m/-dbg$/) {
+            push(@dbg_pkgs, $installable);
+
+        } elsif ($installable->fields->value('Architecture') ne 'all'){
+            push(@arch_dep_pkgs, $installable);
+        }
+    }
+
+    my $dstr = join($VERTICAL_BAR, map { quotemeta($_->name) } @arch_dep_pkgs);
+    my $depregex = qr/^(?:$dstr)$/;
+    for my $dbg_proc (@dbg_pkgs) {
+        my $deps = $processable->binary_relation($dbg_proc->name, 'strong');
+        my $missing = 1;
+        $missing = 0
+          if $deps->matches($depregex, Lintian::Relation::VISIT_PRED_NAME);
+        if ($missing && $dbg_proc->is_transitional) {
+            # If it is a transitional package, allow it to depend
+            # on another -dbg instead.
+            $missing = 0
+              if $deps->matches(qr/-dbg \Z/xsm,
+                Lintian::Relation::VISIT_PRED_NAME);
+        }
+        $self->hint('dbg-package-missing-depends', $dbg_proc->name)
+          if $missing;
+    }
+
+    # Check for a python*-dev build dependency in source packages that
+    # build only arch: all packages.
+    if ($arch_dep_packages == 0 and $build_all->satisfies($PYTHON_DEV)) {
+        $self->hint('build-depends-on-python-dev-with-no-arch-any');
+    }
+
+    my $bdepends = $processable->relation('Build-Depends');
+
+    # libmodule-build-perl
+    # matches() instead of satisfies() because of possible OR relation
+    $self->hint('libmodule-build-perl-needs-to-be-in-build-depends')
+      if $processable->relation('Build-Depends-Indep')
+      ->equals('libmodule-build-perl', Lintian::Relation::VISIT_PRED_NAME)
+      && !$bdepends->equals('libmodule-build-perl',
+        Lintian::Relation::VISIT_PRED_NAME);
+
+    # libmodule-build-tiny-perl
+    $self->hint('libmodule-build-tiny-perl-needs-to-be-in-build-depends')
+      if $processable->relation('Build-Depends-Indep')
+      ->satisfies('libmodule-build-tiny-perl')
+      && !$bdepends->satisfies('libmodule-build-tiny-perl:any');
+
+    return;
+}
+
+# splits "foo:bar (>= 1.2.3) [!i386 ia64] <stage1 !nocheck> <cross>" into
+# ( "foo", "bar", [ ">=", "1.2.3" ], [ [ "i386", "ia64" ], 1 ], [ [ "stage1", "!nocheck" ] , [ "cross" ] ], "" )
+#                                                         ^^^                                               ^^
+#                     count of negated arches, if ! was given                                               ||
+#                                                              rest (should always be "" for valid dependencies)
+sub _split_dep {
+    my $dep = shift;
+    my ($pkg, $dmarch, $version, $darch, $restr)
+      = ($EMPTY, $EMPTY, [$EMPTY,$EMPTY], [[], 0], []);
+
+    if ($dep =~ s/^\s*([^<\s\[\(]+)\s*//) {
+        ($pkg, $dmarch) = split(/:/, $1, 2);
+        $dmarch //= $EMPTY;  # Ensure it is defined (in case there is no ":")
+    }
+
+    if (length $dep) {
+        if ($dep
+            =~ s/\s* \( \s* (<<|<=|>=|>>|[=<>]) \s* ([^\s(]+) \s* \) \s*//x) {
+            @{$version} = ($1, $2);
+        }
+        if ($dep && $dep =~ s/\s*\[([^\]]+)\]\s*//) {
+            my $t = $1;
+            $darch->[0] = [split /\s+/, $t];
+            my $negated = 0;
+            for my $arch (@{ $darch->[0] }) {
+                $negated++ if $arch =~ s/^!//;
+            }
+            $darch->[1] = $negated;
+        }
+        while ($dep && $dep =~ s/\s*<([^>]+)>\s*//) {
+            my $t = $1;
+            push(@{$restr}, [split /\s+/, $t]);
+        }
+    }
+
+    return ($pkg, $dmarch, $version, $darch, $restr, $dep);
+}
+
+sub check_field {
+    my ($self, $field, $data) = @_;
+
+    my $processable = $self->processable;
+
+    my $has_default_mta
+      = $processable->relation($field)
+      ->equals('default-mta', Lintian::Relation::VISIT_PRED_NAME);
+    my $has_mail_transport_agent = $processable->relation($field)
+      ->equals('mail-transport-agent', Lintian::Relation::VISIT_PRED_NAME);
+
+    $self->hint('default-mta-dependency-not-listed-first',"$field: $data")
+      if $processable->relation($field)
+      ->matches(qr/\|\s+default-mta/, Lintian::Relation::VISIT_OR_CLAUSE_FULL);
+
+    if ($has_default_mta) {
+        $self->hint(
+            'default-mta-dependency-does-not-specify-mail-transport-agent',
+            "$field: $data")
+          unless $has_mail_transport_agent;
+    } elsif ($has_mail_transport_agent) {
+        $self->hint(
+            'mail-transport-agent-dependency-does-not-specify-default-mta',
+            "$field: $data")
+          unless $has_default_mta;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/PackageType.pm b/lib/Lintian/Check/Fields/PackageType.pm
new file mode 100644
index 0000000..a8defcd
--- /dev/null
+++ b/lib/Lintian/Check/Fields/PackageType.pm
@@ -0,0 +1,58 @@
+# fields/package_type -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::PackageType;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::Util qw($PKGNAME_REGEX);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub installable {
+    my ($self) = @_;
+
+    return
+      unless $self->processable->fields->declares('Package-Type');
+
+    my $type = $self->processable->fields->value('Package-Type');
+
+    $self->hint('explicit-default-in-package-type')
+      if $type eq 'deb';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Priority.pm b/lib/Lintian/Check/Fields/Priority.pm
new file mode 100644
index 0000000..91fa6bb
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Priority.pm
@@ -0,0 +1,82 @@
+# fields/priority -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Priority;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(any);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub always {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    return
+      unless $fields->declares('Priority');
+
+    my $priority = $fields->unfolded_value('Priority');
+
+    if ($self->processable->type eq 'source'
+        || !$self->processable->is_auto_generated) {
+
+        $self->hint('priority-extra-is-replaced-by-priority-optional')
+          if $priority eq 'extra';
+
+        # Re-map to optional to avoid an additional warning from
+        # lintian
+        $priority = 'optional'
+          if $priority eq 'extra';
+    }
+
+    my $KNOWN_PRIOS = $self->data->load('fields/priorities');
+
+    $self->hint('unknown-priority', $priority)
+      unless $KNOWN_PRIOS->recognizes($priority);
+
+    $self->hint('excessive-priority-for-library-package', $priority)
+      if $self->processable->name =~ /^lib/
+      && $self->processable->name !~ /-bin$/
+      && $self->processable->name !~ /^libc[0-9.]+$/
+      && (any { $_ eq $self->processable->fields->value('Section') }
+        qw(libdevel libs))
+      && (any { $_ eq $priority } qw(required important standard));
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Recommended.pm b/lib/Lintian/Check/Fields/Recommended.pm
new file mode 100644
index 0000000..2c780b8
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Recommended.pm
@@ -0,0 +1,142 @@
+# fields/recommended -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Recommended;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Path::Tiny;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $AT => q{@};
+
+# policy section 5.2 states unequivocally that the two fields Section
+# and Priority are recommended not only in the source paragraph, but
+# also in the binary paragraphs.
+
+# in the author's opinion, however, it does not make sense to flag them
+# there because the same two fields in the source paragraph provide the
+# default for the fields in the binary package paragraph.
+
+# moreover, such duplicate tags would then trigger the tag
+# binary-control-field-duplicates-source elsewhere, which would be
+# super confusing
+
+# policy 5.2
+my @DEBIAN_CONTROL_SOURCE = qw(Section Priority);
+my @DEBIAN_CONTROL_INSTALLABLE = qw(); # Section Priority
+
+# policy 5.3
+my @INSTALLATION_CONTROL = qw(Section Priority);
+
+# policy 5.4
+my @DSC = qw(Package-List);
+
+# policy 5.5
+my @CHANGES = qw(Urgency);
+
+sub source {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+    my @missing_dsc = grep { !$fields->declares($_) } @DSC;
+
+    my $dscfile = path($self->processable->path)->basename;
+    $self->hint('recommended-field', $dscfile, $_) for @missing_dsc;
+
+    my $debian_control = $self->processable->debian_control;
+    my $control_item = $debian_control->item;
+
+    # look at d/control source paragraph
+    my $source_fields = $debian_control->source_fields;
+
+    my @missing_control_source
+      = grep { !$source_fields->declares($_) }@DEBIAN_CONTROL_SOURCE;
+
+    my $source_position = $source_fields->position;
+    my $source_pointer = $control_item->pointer($source_position);
+
+    $self->pointed_hint('recommended-field', $source_pointer,
+        '(in section for source)', $_)
+      for @missing_control_source;
+
+    # look at d/control installable paragraphs
+    for my $installable ($debian_control->installables) {
+
+        my $installable_fields
+          = $debian_control->installable_fields($installable);
+
+        my @missing_control_installable
+          = grep {!$installable_fields->declares($_)}
+          @DEBIAN_CONTROL_INSTALLABLE;
+
+        my $installable_position = $installable_fields->position;
+        my $installable_pointer= $control_item->pointer($installable_position);
+
+        $self->pointed_hint('recommended-field', $installable_pointer,
+            "(in section for $installable)", $_)
+          for @missing_control_installable;
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    my @missing_installation_control
+      = grep { !$fields->declares($_) } @INSTALLATION_CONTROL;
+
+    my $debfile = path($self->processable->path)->basename;
+    $self->hint('recommended-field', $debfile, $_)
+      for @missing_installation_control;
+
+    return;
+}
+
+sub changes {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    my @missing_changes = grep { !$fields->declares($_) } @CHANGES;
+
+    my $changesfile = path($self->processable->path)->basename;
+    $self->hint('recommended-field', $changesfile, $_) for @missing_changes;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Required.pm b/lib/Lintian/Check/Fields/Required.pm
new file mode 100644
index 0000000..3b5213f
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Required.pm
@@ -0,0 +1,144 @@
+# fields/required -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Required;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(all);
+use Path::Tiny;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $AT => q{@};
+
+# policy 5.2
+my @DEBIAN_CONTROL_SOURCE = qw(Source Maintainer Standards-Version);
+my @DEBIAN_CONTROL_INSTALLABLE = qw(Package Architecture Description);
+
+# policy 5.3
+my @INSTALLATION_CONTROL
+  = qw(Package Version Architecture Maintainer Description);
+
+# policy 5.4
+my @DSC = qw(Format Source Version Maintainer Standards-Version
+  Checksums-Sha1 Checksums-Sha256 Files);
+
+# policy 5.5
+# Binary and Description were removed, see Bug#963524
+my @CHANGES = qw(Format Date Source Architecture Version Distribution
+  Maintainer Changes Checksums-Sha1 Checksums-Sha256 Files);
+
+sub source {
+    my ($self) = @_;
+
+    my $debian_control = $self->processable->debian_control;
+
+    # policy 5.6.11
+    if (all { $debian_control->installable_package_type($_) eq 'udeb' }
+        $debian_control->installables) {
+        @DEBIAN_CONTROL_SOURCE
+          = grep { $_ ne 'Standards-Version' } @DEBIAN_CONTROL_SOURCE;
+        @DSC = grep { $_ ne 'Standards-Version' } @DSC;
+    }
+
+    my $fields = $self->processable->fields;
+    my @missing_dsc = grep { !$fields->declares($_) } @DSC;
+
+    my $dscfile = path($self->processable->path)->basename;
+    $self->hint('required-field', $dscfile, $_) for @missing_dsc;
+
+    my $control_item = $debian_control->item;
+
+    # look at d/control source paragraph
+    my $source_fields = $debian_control->source_fields;
+
+    my @missing_control_source
+      = grep { !$source_fields->declares($_) }@DEBIAN_CONTROL_SOURCE;
+
+    my $source_position = $source_fields->position;
+    my $source_pointer = $control_item->pointer($source_position);
+
+    $self->pointed_hint('required-field', $source_pointer,
+        '(in section for source)', $_)
+      for @missing_control_source;
+
+    # look at d/control installable paragraphs
+    for my $installable ($debian_control->installables) {
+
+        my $installable_fields
+          = $debian_control->installable_fields($installable);
+
+        my @missing_control_installable
+          = grep {!$installable_fields->declares($_)}
+          @DEBIAN_CONTROL_INSTALLABLE;
+
+        my $installable_position = $installable_fields->position;
+        my $installable_pointer= $control_item->pointer($installable_position);
+
+        $self->pointed_hint('required-field', $installable_pointer,
+            "(in section for $installable)", $_)
+          for @missing_control_installable;
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    my @missing_installation_control
+      = grep { !$fields->declares($_) } @INSTALLATION_CONTROL;
+
+    my $debfile = path($self->processable->path)->basename;
+    $self->hint('required-field', $debfile, $_)
+      for @missing_installation_control;
+
+    return;
+}
+
+sub changes {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    my @missing_changes = grep { !$fields->declares($_) } @CHANGES;
+
+    my $changesfile = path($self->processable->path)->basename;
+    $self->hint('required-field', $changesfile, $_) for @missing_changes;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Section.pm b/lib/Lintian/Check/Fields/Section.pm
new file mode 100644
index 0000000..f0373a9
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Section.pm
@@ -0,0 +1,140 @@
+# fields/section -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Section;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+our %KNOWN_ARCHIVE_PARTS
+  = map { $_ => 1 } qw(non-free contrib non-free-firmware);
+
+sub udeb {
+    my ($self) = @_;
+
+    my $section = $self->processable->fields->unfolded_value('Section');
+
+    $self->hint('wrong-section-for-udeb', $section)
+      unless $section eq 'debian-installer';
+
+    return;
+}
+
+sub always {
+    my ($self) = @_;
+
+    my $pkg = $self->processable->name;
+
+    return
+      unless $self->processable->fields->declares('Section');
+
+    my $KNOWN_SECTIONS = $self->data->sections;
+
+    # Mapping of package names to section names
+    my $NAME_SECTION_MAPPINGS
+      = $self->data->load('fields/name_section_mappings',qr/\s*=>\s*/);
+
+    my $section = $self->processable->fields->unfolded_value('Section');
+
+    return
+      if $self->processable->type eq 'udeb';
+
+    my @parts = split(m{/}, $section, 2);
+
+    my $division;
+    $division = $parts[0]
+      if @parts > 1;
+
+    my $fraction = $parts[-1];
+
+    if (defined $division) {
+        $self->hint('unknown-section', $section)
+          unless $KNOWN_ARCHIVE_PARTS{$division};
+    }
+
+    if ($fraction eq 'unknown' && !length $division) {
+        $self->hint('section-is-dh_make-template');
+    } else {
+        $self->hint('unknown-section', $section)
+          unless $KNOWN_SECTIONS->recognizes($fraction);
+    }
+
+    # Check package name <-> section.  oldlibs is a special case; let
+    # anything go there.
+    if ($fraction ne 'oldlibs') {
+
+        for my $pattern ($NAME_SECTION_MAPPINGS->all()) {
+
+            my $want = $NAME_SECTION_MAPPINGS->value($pattern);
+
+            next
+              unless $pkg =~ m{$pattern}x;
+
+            unless ($fraction eq $want) {
+
+                my $better
+                  = (defined $division ? "$division/" : $EMPTY) . $want;
+                $self->hint('wrong-section-according-to-package-name',
+                    "$section => $better");
+            }
+
+            last;
+        }
+    }
+
+    if ($fraction eq 'debug') {
+
+        $self->hint('wrong-section-according-to-package-name', $section)
+          if $pkg !~ /-dbg(?:sym)?$/;
+    }
+
+    if ($self->processable->is_transitional) {
+
+        my $priority = $self->processable->fields->unfolded_value('Priority');
+
+        $self->hint('transitional-package-not-oldlibs-optional',
+            "$fraction/$priority")
+          unless $priority eq 'optional' && $fraction eq 'oldlibs';
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Source.pm b/lib/Lintian/Check/Fields/Source.pm
new file mode 100644
index 0000000..455bba3
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Source.pm
@@ -0,0 +1,99 @@
+# fields/source -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Source;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Util qw($PKGNAME_REGEX);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $UNDERSCORE => q{_};
+
+sub source {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    # required in source packages, but dpkg-source already refuses to unpack
+    # without this field (and fields depends on unpacked)
+    return
+      unless $fields->declares('Source');
+
+    my $source = $fields->unfolded_value('Source');
+
+    my $basename = path($self->processable->path)->basename;
+    my ($stem) = split($UNDERSCORE, $basename, 2);
+
+    die encode_utf8(
+        "Source field does not match package name $source != $stem")
+      if $source ne $stem;
+
+    $self->hint('source-field-malformed', $source)
+      if $source !~ /^[a-z0-9][-+\.a-z0-9]+\z/;
+
+    return;
+}
+
+sub always {
+    my ($self) = @_;
+
+    # treated separately above
+    return
+      if $self->processable->type eq 'source';
+
+    my $fields = $self->processable->fields;
+
+    # optional in binary packages
+    return
+      unless $fields->declares('Source');
+
+    my $source = $fields->unfolded_value('Source');
+
+    $self->hint('source-field-malformed', $source)
+      unless $source =~ m{^ $PKGNAME_REGEX
+                         \s*
+                         # Optional Version e.g. (1.0)
+                         (?:\((?:\d+:)?(?:[-\.+:a-zA-Z0-9~]+?)(?:-[\.+a-zA-Z0-9~]+)?\))?\s*$}x;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/StandardsVersion.pm b/lib/Lintian/Check/Fields/StandardsVersion.pm
new file mode 100644
index 0000000..482dd74
--- /dev/null
+++ b/lib/Lintian/Check/Fields/StandardsVersion.pm
@@ -0,0 +1,164 @@
+# fields/standards-version -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2008-2009 Russ Allbery
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::StandardsVersion;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Date::Parse qw(str2time);
+use List::SomeUtils qw(any first_value);
+use POSIX qw(strftime);
+use Sort::Versions;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $DOT => q{.};
+
+const my $MAXIMUM_COMPONENTS_ANALYZED => 3;
+
+const my $DATE_ONLY => '%Y-%m-%d';
+const my $DATE_AND_TIME => '%Y-%m-%d %H:%M:%S UTC';
+
+sub source {
+    my ($self) = @_;
+
+    return
+      unless $self->processable->fields->declares('Standards-Version');
+
+    my $compliance_standard
+      = $self->processable->fields->value('Standards-Version');
+
+    my @compliance_components = split(/[.]/, $compliance_standard);
+    if (@compliance_components < $MAXIMUM_COMPONENTS_ANALYZED
+        || any { !/^\d+$/ } @compliance_components) {
+
+        $self->hint('invalid-standards-version', $compliance_standard);
+        return;
+    }
+
+    $self->hint('standards-version', $compliance_standard);
+
+    my ($compliance_major, $compliance_minor, $compliance_patch)
+      = @compliance_components;
+    my $compliance_normalized
+      = $compliance_major. $DOT. $compliance_minor. $DOT. $compliance_patch;
+
+    my $policy_releases = $self->data->policy_releases;
+    my $latest_standard = $policy_releases->latest_version;
+
+    my ($latest_major, $latest_minor, $latest_patch)
+      = ((split(/[.]/, $latest_standard))[0..$MAXIMUM_COMPONENTS_ANALYZED]);
+
+    # a fourth digit is a non-normative change in policy
+    my $latest_normalized
+      = $latest_major . $DOT . $latest_minor . $DOT . $latest_patch;
+
+    my $changelog_epoch;
+    my $distribution;
+
+    my ($entry) = @{$self->processable->changelog->entries};
+    if (defined $entry) {
+        $changelog_epoch = $entry->Timestamp;
+        $distribution = $entry->Distribution;
+    }
+
+    # assume recent date if there is no changelog; activates most tags
+    $changelog_epoch //= $policy_releases->epoch($latest_standard);
+    $distribution //= $EMPTY;
+
+    unless ($policy_releases->is_known($compliance_standard)) {
+
+        # could be newer
+        if (versioncmp($compliance_standard, $latest_standard) == 1) {
+
+            $self->hint('newer-standards-version',
+                "$compliance_standard (current is $latest_normalized)")
+              unless $distribution =~ /backports/;
+
+        } else {
+            $self->hint('invalid-standards-version', $compliance_standard);
+        }
+
+        return;
+    }
+
+    my $compliance_epoch = $policy_releases->epoch($compliance_standard);
+
+    my $changelog_date = strftime($DATE_ONLY, gmtime $changelog_epoch);
+    my $compliance_date = strftime($DATE_ONLY, gmtime $compliance_epoch);
+
+    my $changelog_timestamp= strftime($DATE_AND_TIME, gmtime $changelog_epoch);
+    my $compliance_timestamp
+      = strftime($DATE_AND_TIME, gmtime $compliance_epoch);
+
+    # catch packages dated prior to release of their standard
+    if ($compliance_epoch > $changelog_epoch) {
+
+        # show precision if needed
+        my $warp_illustration = "($changelog_date < $compliance_date)";
+        $warp_illustration = "($changelog_timestamp < $compliance_timestamp)"
+          if $changelog_date eq $compliance_date;
+
+        $self->hint('timewarp-standards-version', $warp_illustration)
+          unless $distribution eq 'UNRELEASED';
+    }
+
+    my @newer_versions = List::SomeUtils::before {
+        $policy_releases->epoch($_) <= $compliance_epoch
+    }
+    @{$policy_releases->ordered_versions};
+
+    # a fourth digit is a non-normative change in policy
+    my @newer_normative_versions
+      = grep { /^ \d+ [.] \d+ [.] \d+ (?:[.] 0)? $/sx } @newer_versions;
+
+    my @newer_normative_epochs
+      = map { $policy_releases->epoch($_) } @newer_normative_versions;
+
+    my @normative_epochs_then_known
+      = grep { $_ <= $changelog_epoch } @newer_normative_epochs;
+
+    my $outdated_illustration
+      = "$compliance_standard (released $compliance_date) (current is $latest_normalized)";
+
+    # use normative to prevent tag changes on minor new policy edits
+    $self->hint('out-of-date-standards-version', $outdated_illustration)
+      if @normative_epochs_then_known;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Style.pm b/lib/Lintian/Check/Fields/Style.pm
new file mode 100644
index 0000000..fe82d22
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Style.pm
@@ -0,0 +1,84 @@
+# fields/style -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Style;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# the fields in d/control provide the values for many fields elsewhere
+sub source {
+    my ($self) = @_;
+
+    my $debian_control = $self->processable->debian_control;
+    my $control_item = $debian_control->item;
+
+    # look at d/control source paragraph
+    my $source_fields = $debian_control->source_fields;
+
+    $self->check_style($source_fields, $control_item);
+
+    for my $installable ($debian_control->installables) {
+
+        # look at d/control installable paragraphs
+        my $installable_fields
+          = $debian_control->installable_fields($installable);
+
+        $self->check_style($installable_fields, $control_item);
+    }
+
+    return;
+}
+
+sub check_style {
+    my ($self, $fields, $item) = @_;
+
+    for my $name ($fields->names) {
+
+        # title-case the field name
+        my $standard = lc $name;
+        $standard =~ s/\b(\w)/\U$1/g;
+
+        # capitalize up to three letters after an X, if followed by hyphen
+        $standard =~ s/^(X[SBC]{1,3})-/\U$1-/i;
+
+        my $position = $fields->position($name);
+        my $pointer = $item->pointer($position);
+
+        $self->pointed_hint('cute-field', $pointer, "$name vs $standard")
+          unless $name eq $standard;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Subarchitecture.pm b/lib/Lintian/Check/Fields/Subarchitecture.pm
new file mode 100644
index 0000000..185f601
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Subarchitecture.pm
@@ -0,0 +1,55 @@
+# fields/subarchitecture -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Subarchitecture;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub always {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    #---- Subarchitecture (udeb)
+
+    # may trigger unfolding tag
+    my $subarch = $fields->unfolded_value('Subarchitecture');
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/TerminalControl.pm b/lib/Lintian/Check/Fields/TerminalControl.pm
new file mode 100644
index 0000000..0d2b02b
--- /dev/null
+++ b/lib/Lintian/Check/Fields/TerminalControl.pm
@@ -0,0 +1,62 @@
+# fields/terminal-control -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::TerminalControl;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $ESCAPE => qq{\033};
+
+sub always {
+    my ($self) = @_;
+
+    my @names = $self->processable->fields->names;
+
+    # fields that contain ESC characters
+    my @escaped
+      = grep { index($self->processable->fields->value($_), $ESCAPE) >= 0 }
+      @names;
+
+    $self->hint('ansi-escape', $_, $self->processable->fields->value($_))
+      for @escaped;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Trimmed.pm b/lib/Lintian/Check/Fields/Trimmed.pm
new file mode 100644
index 0000000..24777f7
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Trimmed.pm
@@ -0,0 +1,52 @@
+# fields/trimmed -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Trimmed;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub always {
+    my ($self) = @_;
+
+    my @all = $self->processable->fields->names;
+
+    for my $name (@all) {
+
+        my $value = $self->processable->fields->value($name);
+        $self->hint('trimmed-field', $name, $value);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Unknown.pm b/lib/Lintian/Check/Fields/Unknown.pm
new file mode 100644
index 0000000..79a0ddd
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Unknown.pm
@@ -0,0 +1,86 @@
+# fields/unknown -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Unknown;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Path::Tiny;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# Whitelist of XS-* source fields
+my %source_field_whitelist = (
+    'Autobuild'      => 1,
+    'Go-Import-Path' => 1,
+    'Ruby-Versions'  => 1,
+);
+
+sub source {
+    my ($self) = @_;
+
+    my $KNOWN_SOURCE_FIELDS= $self->data->load('common/source-fields');
+    my @unknown= $self->processable->fields->extra($KNOWN_SOURCE_FIELDS->all);
+
+    # The grep filter is a workaround for #1014885 and #1029471
+    $self->hint('unknown-field', $_)
+      for grep { !exists($source_field_whitelist{$_}) } @unknown;
+
+    return;
+}
+
+sub binary {
+    my ($self) = @_;
+
+    my $KNOWN_BINARY_FIELDS= $self->data->load('fields/binary-fields');
+    my @unknown= $self->processable->fields->extra($KNOWN_BINARY_FIELDS->all);
+
+    $self->hint('unknown-field', $_)for @unknown;
+
+    return;
+}
+
+sub udeb {
+    my ($self) = @_;
+
+    my $KNOWN_UDEB_FIELDS = $self->data->load('fields/udeb-fields');
+    my @unknown = $self->processable->fields->extra($KNOWN_UDEB_FIELDS->all);
+
+    $self->hint('unknown-field', $_)for @unknown;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Uploaders.pm b/lib/Lintian/Check/Fields/Uploaders.pm
new file mode 100644
index 0000000..bfad0c4
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Uploaders.pm
@@ -0,0 +1,71 @@
+# fields/uploaders -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Uploaders;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub always {
+    my ($self) = @_;
+
+    return
+      unless $self->processable->fields->declares('Uploaders');
+
+    my $uploaders = $self->processable->fields->value('Uploaders');
+
+    # Note, not expected to hit on uploaders anymore, as dpkg
+    # now strips newlines for the .dsc, and the newlines don't
+    # hurt in debian/control
+
+    # check for empty field see  #783628
+    if ($uploaders =~ /,\s*,/) {
+        $self->hint('uploader-name-missing','you have used a double comma');
+        $uploaders =~ s/,\s*,/,/g;
+    }
+
+    if ($self->processable->fields->declares('Maintainer')) {
+
+        my $maintainer = $self->processable->fields->value('Maintainer');
+
+        $self->hint('maintainer-also-in-uploaders')
+          if $uploaders =~ m/\Q$maintainer/;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Urgency.pm b/lib/Lintian/Check/Fields/Urgency.pm
new file mode 100644
index 0000000..7e87309
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Urgency.pm
@@ -0,0 +1,60 @@
+# fields/urgency -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software.  It is distributed under the terms of
+# the GNU General Public License as published by the Free Software
+# Foundation; either version 2 of the License, or (at your option) any
+# later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Urgency;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(any);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub changes {
+    my ($self) = @_;
+
+    return
+      unless $self->processable->fields->declares('Urgency');
+
+    my $urgency = $self->processable->fields->value('Urgency');
+
+    # translate to lowercase
+    my $lowercase = lc $urgency;
+
+    # discard anything after the first word
+    $lowercase =~ s/ .*//;
+
+    $self->hint('bad-urgency-in-changes-file', $urgency)
+      unless any { $lowercase =~ $_ } qw(low medium high critical emergency);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Vcs.pm b/lib/Lintian/Check/Fields/Vcs.pm
new file mode 100644
index 0000000..8bf7858
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Vcs.pm
@@ -0,0 +1,378 @@
+# fields/vcs -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2019 Chris Lamb <lamby@debian.org>
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Vcs;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any);
+
+const my $EMPTY => q{};
+const my $QUESTION_MARK => q{?};
+
+const my $NOT_EQUALS => q{!=};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+my %VCS_EXTRACT = (
+    Browser => sub { return @_;},
+    Arch    => sub { return @_;},
+    Bzr     => sub { return @_;},
+    # cvs rootdir followed by optional module name:
+    Cvs     => sub { return shift =~ /^(.+?)(?:\s+(\S*))?$/;},
+    Darcs   => sub { return @_;},
+    # hg uri followed by optional -b branchname
+    Hg      => sub { return shift =~ /^(.+?)(?:\s+-b\s+(\S*))?$/;},
+    # git uri followed by optional "[subdir]", "-b branchname" etc.
+    Git     => sub {
+        return shift =~ /^(.+?)(?:(?:\s+\[(\S*)\])?(?:\s+-b\s+(\S*))?){0,2}$/;
+    },
+    Svn     => sub { return @_;},
+    # New "mtn://host?branch" uri or deprecated "host branch".
+    Mtn     => sub { return shift =~ /^(.+?)(?:\s+\S+)?$/;},
+);
+
+my %VCS_CANONIFY = (
+    Browser => sub {
+        $_[0] =~ s{https?://svn\.debian\.org/wsvn/}
+                  {https://anonscm.debian.org/viewvc/};
+        $_[0] =~ s{https?\Q://git.debian.org/?p=\E}
+                  {https://anonscm.debian.org/git/};
+        $_[0] =~ s{https?\Q://bzr.debian.org/loggerhead/\E}
+                  {https://anonscm.debian.org/loggerhead/};
+        $_[0] =~ s{https?\Q://salsa.debian.org/\E([^/]+/[^/]+)\.git/?$}
+                  {https://salsa.debian.org/$1};
+
+        if ($_[0] =~ m{https?\Q://anonscm.debian.org/viewvc/\E}xsm) {
+            if ($_[0] =~ s{\?(.*[;\&])?op=log(?:[;\&](.*))?\Z}{}xsm) {
+                my (@keep) = ($1, $2, $3);
+                my $final = join($EMPTY, grep {defined} @keep);
+
+                $_[0] .= $QUESTION_MARK . $final
+                  if $final ne $EMPTY;
+
+                $_[1] = 'vcs-field-bitrotted';
+            }
+        }
+    },
+    Cvs      => sub {
+        if (
+            $_[0] =~ s{\@(?:cvs\.alioth|anonscm)\.debian\.org:/cvsroot/}
+                      {\@anonscm.debian.org:/cvs/}
+        ) {
+            $_[1] = 'vcs-field-bitrotted';
+        }
+        $_[0]=~ s{\@\Qcvs.alioth.debian.org:/cvs/}{\@anonscm.debian.org:/cvs/};
+    },
+    Arch     => sub {
+        $_[0] =~ s{https?\Q://arch.debian.org/arch/\E}
+                  {https://anonscm.debian.org/arch/};
+    },
+    Bzr     => sub {
+        $_[0] =~ s{https?\Q://bzr.debian.org/\E}
+                  {https://anonscm.debian.org/bzr/};
+        $_[0] =~ s{https?\Q://anonscm.debian.org/bzr/bzr/\E}
+                  {https://anonscm.debian.org/bzr/};
+    },
+    Git     => sub {
+        if (
+            $_[0] =~ s{git://(?:git|anonscm)\.debian\.org/~}
+                      {https://anonscm.debian.org/git/users/}
+        ) {
+            $_[1] = 'vcs-git-uses-invalid-user-uri';
+        }
+        $_[0] =~ s{(https?://.*?\.git)(?:\.git)+$}{$1};
+        $_[0] =~ s{https?\Q://git.debian.org/\E(?:git/?)?}
+                  {https://anonscm.debian.org/git/};
+        $_[0] =~ s{https?\Q://anonscm.debian.org/git/git/\E}
+                  {https://anonscm.debian.org/git/};
+        $_[0] =~ s{\Qgit://git.debian.org/\E(?:git/?)?}
+                  {https://anonscm.debian.org/git/};
+        $_[0] =~ s{\Qgit://anonscm.debian.org/git/\E}
+                  {https://anonscm.debian.org/git/};
+        $_[0] =~ s{https?\Q://salsa.debian.org/\E([^/]+/[^/\.]+)(?!\.git)$}
+                  {https://salsa.debian.org/$1.git};
+    },
+    Hg      => sub {
+        $_[0] =~ s{https?\Q://hg.debian.org/\E}
+                  {https://anonscm.debian.org/hg/};
+        $_[0] =~ s{https?\Q://anonscm.debian.org/hg/hg/\E}
+                  {https://anonscm.debian.org/hg/};
+    },
+    Svn     => sub {
+        $_[0] =~ s{\Qsvn://cvs.alioth.debian.org/\E}
+                  {svn://anonscm.debian.org/};
+        $_[0] =~ s{\Qsvn://svn.debian.org/\E}
+                  {svn://anonscm.debian.org/};
+        $_[0] =~ s{\Qsvn://anonscm.debian.org/svn/\E}
+                  {svn://anonscm.debian.org/};
+    },
+);
+
+# Valid URI formats for the Vcs-* fields
+# currently only checks the protocol, not the actual format of the URI
+my %VCS_RECOMMENDED_URIS = (
+    Browser => qr{^https?://},
+    Arch    => qr{^https?://},
+    Bzr     => qr{^(?:lp:|(?:nosmart\+)?https?://)},
+    Cvs     => qr{^:(?:pserver:|ext:_?anoncvs)},
+    Darcs   => qr{^https?://},
+    Hg      => qr{^https?://},
+    Git     => qr{^(?:git|https?|rsync)://},
+    Svn     => qr{^(?:svn|(?:svn\+)?https?)://},
+    Mtn     => qr{^mtn://},
+);
+
+my %VCS_VALID_URIS = (
+    Arch    => qr{^https?://},
+    Bzr     => qr{^(?:sftp|(?:bzr\+)?ssh)://},
+    Cvs     => qr{^(?:-d\s*)?:(?:ext|pserver):},
+    Hg      => qr{^ssh://},
+    Git     => qr{^(?:git\+)?ssh://|^[\w.]+@[a-zA-Z0-9.]+:[/a-zA-Z0-9.]},
+    Svn     => qr{^(?:svn\+)?ssh://},
+    Mtn     => qr{^[\w.-]+$},
+);
+
+has VCS_HOSTERS_BY_PATTERN => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %vcs_hosters_by_pattern;
+
+        my $KNOWN_VCS_HOSTERS
+          = $self->data->load('fields/vcs-hosters',qr/\s*~~\s*/);
+
+        for my $pattern ($KNOWN_VCS_HOSTERS->all) {
+
+            my @known_hosters
+              = split(m{,}, $KNOWN_VCS_HOSTERS->value($pattern));
+            $vcs_hosters_by_pattern{$pattern} = \@known_hosters;
+        }
+
+        return \%vcs_hosters_by_pattern;
+    }
+);
+
+sub always {
+    my ($self) = @_;
+
+    my $type = $self->processable->type;
+    my $processable = $self->processable;
+
+    # team-maintained = maintainer or uploaders field contains a mailing list
+    my $is_teammaintained = 0;
+    my $team_email = $EMPTY;
+    # co-maintained = maintained by an informal group of people,
+    # i. e. >= 1 uploader and not team-maintained
+    my $is_comaintained = 0;
+    my $is_maintained_by_individual = 1;
+    my $num_uploaders = 0;
+    for my $field (qw(Maintainer Uploaders)) {
+
+        next
+          unless $processable->fields->declares($field);
+
+        my $maintainer = $processable->fields->unfolded_value($field);
+
+        if ($maintainer =~ /\b(\S+\@lists(?:\.alioth)?\.debian\.org)\b/
+            || $maintainer =~ /\b(\S+\@tracker\.debian\.org)\b/) {
+            $is_teammaintained = 1;
+            $team_email = $1;
+            $is_maintained_by_individual = 0;
+        }
+
+        if ($field eq 'Uploaders') {
+
+            # check for empty field see  #783628
+            $maintainer =~ s/,\s*,/,/g
+              if $maintainer =~ m/,\s*,/;
+
+            my @uploaders = map { split /\@\S+\K\s*,\s*/ }
+              split />\K\s*,\s*/, $maintainer;
+
+            $num_uploaders = scalar @uploaders;
+
+            if (@uploaders) {
+                $is_comaintained = 1
+                  unless $is_teammaintained;
+                $is_maintained_by_individual = 0;
+            }
+
+        }
+    }
+
+    $self->hint('package-is-team-maintained', $team_email,
+        "(with $num_uploaders uploaders)")
+      if $is_teammaintained;
+    $self->hint('package-is-co-maintained', "(with $num_uploaders uploaders)")
+      if $is_comaintained;
+    $self->hint('package-is-maintained-by-individual')
+      if $is_maintained_by_individual;
+
+    my %seen_vcs;
+    for my $platform (keys %VCS_EXTRACT) {
+
+        my $splitter = $VCS_EXTRACT{$platform};
+
+        my $fieldname = "Vcs-$platform";
+        my $maintainer = $processable->fields->value('Maintainer');
+
+        next
+          unless $processable->fields->declares($fieldname);
+
+        my $uri = $processable->fields->unfolded_value($fieldname);
+
+        my @parts = $splitter->($uri);
+        if (not @parts or not $parts[0]) {
+            $self->hint('vcs-field-uses-unknown-uri-format', $platform, $uri);
+        } else {
+            if (    $VCS_RECOMMENDED_URIS{$platform}
+                and $parts[0] !~ $VCS_RECOMMENDED_URIS{$platform}) {
+                if (    $VCS_VALID_URIS{$platform}
+                    and $parts[0] =~ $VCS_VALID_URIS{$platform}) {
+                    $self->hint('vcs-field-uses-not-recommended-uri-format',
+                        $platform, $uri);
+                } else {
+                    $self->hint('vcs-field-uses-unknown-uri-format',
+                        $platform,$uri);
+                }
+            }
+
+            $self->hint('vcs-field-has-unexpected-spaces', $platform, $uri)
+              if (any { $_ and /\s/} @parts);
+
+            $self->hint('vcs-field-uses-insecure-uri', $platform, $uri)
+              if $parts[0] =~ m{^(?:git|(?:nosmart\+)?http|svn)://}
+              || $parts[0] =~ m{^(?:lp|:pserver):};
+        }
+
+        if ($VCS_CANONIFY{$platform}) {
+
+            my $canonicalized = $parts[0];
+            my $tag = 'vcs-field-not-canonical';
+
+            foreach my $canonify ($VCS_CANONIFY{$platform}) {
+                $canonify->($canonicalized, $tag);
+            }
+
+            $self->hint($tag, $platform, $parts[0], $canonicalized)
+              unless $canonicalized eq $parts[0];
+        }
+
+        if ($platform eq 'Browser') {
+
+            $self->hint('vcs-browser-links-to-empty-view', $uri)
+              if $uri =~ /rev=0&sc=0/;
+
+        } else {
+            $self->hint('vcs', lc $platform);
+            $self->hint('vcs-uri', $platform, $uri);
+            $seen_vcs{$platform}++;
+
+            for my $pattern (keys %{$self->VCS_HOSTERS_BY_PATTERN}) {
+
+                # warn once
+                my $known_hoster
+                  = @{$self->VCS_HOSTERS_BY_PATTERN->{$pattern}}[0];
+
+                $self->hint('vcs-field-mismatch',
+                    "Vcs-$platform", $NOT_EQUALS, "Vcs-$known_hoster",$uri)
+                  if $uri =~ m/^ $pattern /xi
+                  && $platform ne $known_hoster
+                  && $platform ne 'Browser';
+            }
+        }
+
+        if ($uri =~ m{//(.+)\.debian\.org/}) {
+
+            $self->hint('vcs-obsolete-in-debian-infrastructure',
+                $platform, $uri)
+              unless $1 =~ m{^(?:salsa|.*\.dgit)$};
+
+        }
+
+        # orphaned
+        if ($maintainer =~ /packages\@qa.debian.org/ && $platform ne 'Browser')
+        {
+            if ($uri =~ m{//(?:.+)\.debian\.org/}) {
+
+                $self->hint('orphaned-package-maintained-in-private-space',
+                    $fieldname, $uri)
+                  unless $uri =~ m{//salsa\.debian\.org/debian/}
+                  || $uri =~ m{//git\.dgit\.debian\.org/};
+
+            } else {
+
+                $self->hint(
+                    'orphaned-package-not-maintained-in-debian-infrastructure',
+                    $fieldname, $uri
+                );
+            }
+        }
+    }
+
+    $self->hint('vcs-fields-use-more-than-one-vcs',
+        (sort map { lc } keys %seen_vcs))
+      if keys %seen_vcs > 1;
+
+    $self->hint('co-maintained-package-with-no-vcs-fields')
+      if $type eq 'source'
+      and ($is_comaintained or $is_teammaintained)
+      and not %seen_vcs;
+
+    # Check for missing Vcs-Browser headers
+    unless ($processable->fields->declares('Vcs-Browser')) {
+
+        for my $pattern (keys %{$self->VCS_HOSTERS_BY_PATTERN}) {
+
+            # warn once
+            my $platform = @{$self->VCS_HOSTERS_BY_PATTERN->{$pattern}}[0];
+
+            my $fieldname = "Vcs-$platform";
+            my $url = $processable->fields->value($fieldname);
+
+            $self->hint('missing-vcs-browser-field', $fieldname, $url)
+              if $url =~ m/^ $pattern /xi;
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Version.pm b/lib/Lintian/Check/Fields/Version.pm
new file mode 100644
index 0000000..77ee0f9
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Version.pm
@@ -0,0 +1,100 @@
+# fields/version -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2021 Felix Lechner
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Version;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Dpkg::Version;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub always {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    return
+      unless $fields->declares('Version');
+
+    my $version = $fields->unfolded_value('Version');
+
+    my $dversion = Dpkg::Version->new($version);
+    unless ($dversion->is_valid) {
+        $self->hint('bad-version-number', $version);
+        return;
+    }
+
+    my ($epoch, $upstream, $debian)
+      = ($dversion->epoch, $dversion->version, $dversion->revision);
+
+    # Dpkg::Version sets the debian revision to 0 if there is
+    # no revision.  So we need to check if the raw version
+    # ends with "-0".
+    $self->hint('debian-revision-is-zero', $version)
+      if $version =~ /-0$/;
+
+    my $ubuntu;
+    if($debian =~ /^(?:[^.]+)(?:\.[^.]+)?(?:\.[^.]+)?(\..*)?$/){
+        my $extra = $1;
+        if (
+            defined $extra
+            && $debian =~ m{\A
+                            (?:[^.]+ubuntu[^.]+)(?:\.\d+){1,3}(\..*)?
+                            \Z}xsm
+        ) {
+            $ubuntu = 1;
+            $extra = $1;
+        }
+
+        $self->hint('debian-revision-not-well-formed', $version)
+          if defined $extra;
+
+    } else {
+        $self->hint('debian-revision-not-well-formed', $version);
+    }
+
+    if ($self->processable->type eq 'source') {
+
+        $self->hint('binary-nmu-debian-revision-in-source', $version)
+          if ($debian =~ /^[^.-]+\.[^.-]+\./ && !$ubuntu)
+          || $version =~ /\+b\d+$/;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Version/Derivative.pm b/lib/Lintian/Check/Fields/Version/Derivative.pm
new file mode 100644
index 0000000..9385fa4
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Version/Derivative.pm
@@ -0,0 +1,82 @@
+# fields/version/derivative -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2021 Felix Lechner
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Version::Derivative;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Dpkg::Version;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    return
+      unless $fields->declares('Version');
+
+    my $version = $fields->unfolded_value('Version');
+
+    my $dversion = Dpkg::Version->new($version);
+    return
+      unless $dversion->is_valid;
+
+    my ($epoch, $upstream, $debian)
+      = ($dversion->epoch, $dversion->version, $dversion->revision);
+
+    my $DERIVATIVE_VERSIONS
+      = $self->data->load('fields/derivative-versions',qr/\s*~~\s*/);
+
+    unless ($self->processable->native) {
+
+        for my $pattern ($DERIVATIVE_VERSIONS->all) {
+
+            next
+              if $version =~ m/$pattern/;
+
+            my $explanation = $DERIVATIVE_VERSIONS->value($pattern);
+
+            $self->hint('invalid-version-number-for-derivative',
+                $version,"($explanation)");
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Version/Repack/Count.pm b/lib/Lintian/Check/Fields/Version/Repack/Count.pm
new file mode 100644
index 0000000..c793385
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Version/Repack/Count.pm
@@ -0,0 +1,65 @@
+# fields/version/repack/count -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2021 Kentaro Hayashi
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Version::Repack::Count;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    # repack counts in native packages are dealt with elsewhere
+    return
+      if $self->processable->native;
+
+    my $fields = $self->processable->fields;
+
+    return
+      unless $fields->declares('Version');
+
+    my $version = $fields->unfolded_value('Version');
+
+    $self->hint('anticipated-repack-count', $version)
+      if $version =~ m{ dfsg [01] - }x;
+
+    $self->hint('dot-before-repack-count', $version)
+      if $version =~ / dfsg [.] \d+ /x;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Version/Repack/Native.pm b/lib/Lintian/Check/Fields/Version/Repack/Native.pm
new file mode 100644
index 0000000..6ca1602
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Version/Repack/Native.pm
@@ -0,0 +1,63 @@
+# fields/version/repack/native -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2021 Felix Lechner
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Version::Repack::Native;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    return
+      unless $fields->declares('Version');
+
+    my $version = $fields->unfolded_value('Version');
+
+    # Checks for the dfsg convention for repackaged upstream
+    # source.  Only check these against the source package to not
+    # repeat ourselves too much.
+    $self->hint('dfsg-version-in-native-package', $version)
+      if $version =~ /dfsg/
+      && $self->processable->native;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Version/Repack/Period.pm b/lib/Lintian/Check/Fields/Version/Repack/Period.pm
new file mode 100644
index 0000000..12e8928
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Version/Repack/Period.pm
@@ -0,0 +1,60 @@
+# fields/version/repack/period -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2021 Felix Lechner
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Version::Repack::Period;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    return
+      unless $fields->declares('Version');
+
+    my $version = $fields->unfolded_value('Version');
+
+    $self->hint('dfsg-version-with-period', $version)
+      if $version =~ m{ [.] dfsg }x
+      && !$self->processable->native;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Version/Repack/Tilde.pm b/lib/Lintian/Check/Fields/Version/Repack/Tilde.pm
new file mode 100644
index 0000000..206b288
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Version/Repack/Tilde.pm
@@ -0,0 +1,60 @@
+# fields/version/repack/tilde -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2021 Kentaro Hayashi
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Version::Repack::Tilde;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    return
+      unless $fields->declares('Version');
+
+    my $version = $fields->unfolded_value('Version');
+
+    $self->hint('dfsg-version-with-tilde', $version)
+      if $version =~ /~dfsg/
+      && !$self->processable->native;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fields/Version/Repack/Typo.pm b/lib/Lintian/Check/Fields/Version/Repack/Typo.pm
new file mode 100644
index 0000000..c466df2
--- /dev/null
+++ b/lib/Lintian/Check/Fields/Version/Repack/Typo.pm
@@ -0,0 +1,64 @@
+# fields/version/repack/typo -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2021 Felix Lechner
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fields::Version::Repack::Typo;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Dpkg::Version qw(version_check);
+
+use Lintian::Relation::Version qw(versions_compare);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    return
+      unless $fields->declares('Version');
+
+    my $version = $fields->unfolded_value('Version');
+
+    $self->hint('dfsg-version-misspelled', $version)
+      if $version =~ /dsfg/
+      && !$self->processable->native;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Architecture.pm b/lib/Lintian/Check/Files/Architecture.pm
new file mode 100644
index 0000000..70cab47
--- /dev/null
+++ b/lib/Lintian/Check/Files/Architecture.pm
@@ -0,0 +1,105 @@
+# files/architecture -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Architecture;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has TRIPLETS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $DEB_HOST_MULTIARCH= $self->data->architectures->deb_host_multiarch;
+        my %triplets = map { $DEB_HOST_MULTIARCH->{$_} => $_ }
+          keys %{$DEB_HOST_MULTIARCH};
+
+        return \%triplets;
+    }
+);
+
+has depends_on_architecture => (is => 'rw', default => 0);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # for directories
+    if ($item->name =~ m{^(?:usr/)?lib/([^/]+)/$}) {
+
+        my $potential_triplet = $1;
+
+        if (exists $self->TRIPLETS->{$potential_triplet}) {
+
+            my $from_triplet = $self->TRIPLETS->{$potential_triplet};
+            my $port = $self->processable->fields->value('Architecture');
+
+            $self->pointed_hint('triplet-dir-and-architecture-mismatch',
+                $item->pointer, "is for $from_triplet instead of $port")
+              unless $from_triplet eq $port;
+        }
+    }
+
+    # for files
+    if ($item->dirname =~ m{^(?:usr)?/lib/([^/]+)/$}) {
+
+        my $potential_triplet = $1;
+
+        $self->depends_on_architecture(1)
+          if exists $self->TRIPLETS->{$potential_triplet};
+    }
+
+    $self->depends_on_architecture(1)
+      if $item->is_file
+      && $item->size > 0
+      && $item->file_type !~ m/^very short file/
+      && $item->file_type !~ m/\bASCII text\b/
+      && $item->name !~ m{^usr/share/};
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    $self->hint('package-contains-no-arch-dependent-files')
+      if !$self->depends_on_architecture
+      && $self->processable->fields->value('Architecture') ne 'all'
+      && $self->processable->type ne 'udeb'
+      && !$self->processable->is_transitional
+      && !$self->processable->is_meta_package;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Artifact.pm b/lib/Lintian/Check/Files/Artifact.pm
new file mode 100644
index 0000000..5344cfc
--- /dev/null
+++ b/lib/Lintian/Check/Files/Artifact.pm
@@ -0,0 +1,140 @@
+# files/artifact -- lintian check script -*- perl -*-
+#
+# based on debhelper check,
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Artifact;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(first_value);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# Directory checks.  These regexes match a directory that shouldn't be in the
+# source package and associate it with a tag (minus the leading
+# source-contains or debian-adds).  Note that only one of these regexes
+# should trigger for any single directory.
+my @directory_checks = (
+    [qr{^(.+/)?CVS/?$}        => 'cvs-control-dir'],
+    [qr{^(.+/)?\.svn/?$}      => 'svn-control-dir'],
+    [qr{^(.+/)?\.bzr/?$}      => 'bzr-control-dir'],
+    [qr{^(.+/)?\{arch\}/?$}   => 'arch-control-dir'],
+    [qr{^(.+/)?\.arch-ids/?$} => 'arch-control-dir'],
+    [qr{^(.+/)?,,.+/?$}       => 'arch-control-dir'],
+    [qr{^(.+/)?\.git/?$}      => 'git-control-dir'],
+    [qr{^(.+/)?\.hg/?$}       => 'hg-control-dir'],
+    [qr{^(.+/)?\.be/?$}       => 'bts-control-dir'],
+    [qr{^(.+/)?\.ditrack/?$}  => 'bts-control-dir'],
+
+    # Special case (can only be triggered for diffs)
+    [qr{^(.+/)?\.pc/?$} => 'quilt-control-dir'],
+);
+
+# File checks.  These regexes match files that shouldn't be in the source
+# package and associate them with a tag (minus the leading source-contains or
+# debian-adds).  Note that only one of these regexes should trigger for any
+# given file.
+my @file_checks = (
+    [qr{^(.+/)?svn-commit\.(.+\.)?tmp$} => 'svn-commit-file'],
+    [qr{^(.+/)?svk-commit.+\.tmp$}      => 'svk-commit-file'],
+    [qr{^(.+/)?\.arch-inventory$}       => 'arch-inventory-file'],
+    [qr{^(.+/)?\.hgtags$}               => 'hg-tags-file'],
+    [qr{^(.+/)?\.\#(.+?)\.\d+(\.\d+)*$} => 'cvs-conflict-copy'],
+    [qr{^(.+/)?(.+?)\.(r[1-9]\d*)$}     => 'svn-conflict-file'],
+    [qr{\.(orig|rej)$}                  => 'patch-failure-file'],
+    [qr{((^|/)[^/]+\.swp|~)$}           => 'editor-backup-file'],
+);
+
+sub source {
+    my ($self) = @_;
+
+    my @added_by_debian;
+    my $prefix;
+    if ($self->processable->native) {
+
+        @added_by_debian = @{$self->processable->patched->sorted_list};
+        $prefix = 'source-contains';
+
+    } else {
+        my $patched = $self->processable->patched;
+        my $orig = $self->processable->orig;
+
+        @added_by_debian
+          = grep { !defined $orig->lookup($_->name) } @{$patched->sorted_list};
+
+        # remove root quilt control folder and all paths in it
+        # created when 3.0 (quilt) source packages are unpacked
+        @added_by_debian = grep { $_->name !~ m{^.pc/} } @added_by_debian
+          if $self->processable->source_format eq '3.0 (quilt)';
+
+        my @common_items
+          = grep { defined $orig->lookup($_->name) } @{$patched->sorted_list};
+        my @touched_by_debian
+          = grep { $_->md5sum ne $orig->lookup($_->name)->md5sum }
+          @common_items;
+
+        $self->hint('no-debian-changes')
+          unless @added_by_debian || @touched_by_debian;
+
+        $prefix = 'debian-adds';
+    }
+
+    # ignore lintian test set; should use automatic loop in the future
+    @added_by_debian = grep { $_->name !~ m{^t/} } @added_by_debian
+      if $self->processable->source_name eq 'lintian';
+
+    my @directories = grep { $_->is_dir } @added_by_debian;
+    for my $directory (@directories) {
+
+        my $rule = first_value { $directory->name =~ /$_->[0]/s }
+        @directory_checks;
+        $self->pointed_hint("${prefix}-$rule->[1]", $directory->pointer)
+          if defined $rule;
+    }
+
+    my @files = grep { $_->is_file } @added_by_debian;
+    for my $item (@files) {
+
+        my $rule = first_value { $item->name =~ /$_->[0]/s } @file_checks;
+        $self->pointed_hint("${prefix}-$rule->[1]", $item->pointer)
+          if defined $rule;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Banned.pm b/lib/Lintian/Check/Files/Banned.pm
new file mode 100644
index 0000000..81b5ae7
--- /dev/null
+++ b/lib/Lintian/Check/Files/Banned.pm
@@ -0,0 +1,113 @@
+# files/banned -- lintian check script -*- perl -*-
+#
+# based on debhelper check,
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Banned;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any);
+use Unicode::UTF8 qw(encode_utf8);
+
+const my $MD5SUM_DATA_FIELDS => 5;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub _md5sum_based_lintian_data {
+    my ($self, $filename) = @_;
+
+    my $data = $self->data->load($filename,qr/\s*\~\~\s*/);
+
+    my %md5sum_data;
+
+    for my $md5sum ($data->all) {
+
+        my $value = $data->value($md5sum);
+
+        my ($sha1, $sha256, $name, $reason, $link)
+          = split(/ \s* ~~ \s* /msx, $value, $MD5SUM_DATA_FIELDS);
+
+        die encode_utf8("Syntax error in $filename $.")
+          if any { !defined } ($sha1, $sha256, $name, $reason, $link);
+
+        $md5sum_data{$md5sum} = {
+            'sha1'   => $sha1,
+            'sha256' => $sha256,
+            'name'   => $name,
+            'reason' => $reason,
+            'link'   => $link,
+        };
+    }
+
+    return \%md5sum_data;
+}
+
+has NON_DISTRIBUTABLE_FILES => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->_md5sum_based_lintian_data(
+            'cruft/non-distributable-files');
+    }
+);
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    my $banned = $self->NON_DISTRIBUTABLE_FILES->{$item->md5sum};
+    if (defined $banned) {
+        my $usualname = $banned->{'name'};
+        my $reason = $banned->{'reason'};
+        my $link = $banned->{'link'};
+
+        $self->pointed_hint(
+            'license-problem-md5sum-non-distributable-file',
+            $item->pointer, "usual name is $usualname.",
+            $reason, "See also $link."
+        );
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Banned/CompiledHelp.pm b/lib/Lintian/Check/Files/Banned/CompiledHelp.pm
new file mode 100644
index 0000000..efb5eee
--- /dev/null
+++ b/lib/Lintian/Check/Files/Banned/CompiledHelp.pm
@@ -0,0 +1,58 @@
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Banned::CompiledHelp;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # .chm files are usually generated by non-free software
+    $self->pointed_hint('source-contains-prebuilt-ms-help-file',$item->pointer)
+      if  $item->basename =~ /\.chm$/i
+      && $item->file_type eq 'MS Windows HtmlHelp Data'
+      && $item->bytes !~ / Halibut, /msx;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Banned/Lenna.pm b/lib/Lintian/Check/Files/Banned/Lenna.pm
new file mode 100644
index 0000000..3bfcb2c
--- /dev/null
+++ b/lib/Lintian/Check/Files/Banned/Lenna.pm
@@ -0,0 +1,109 @@
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Banned::Lenna;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# known bad files
+has LENNA_BLACKLIST => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %blacklist;
+
+        my $data = $self->data->load('files/banned/lenna/blacklist',
+            qr/ \s* ~~ \s* /x);
+
+        for my $md5sum ($data->all) {
+
+            my $value = $data->value($md5sum);
+
+            my ($sha1, $sha256, $name, $link)
+              = split(/ \s* ~~ \s* /msx, $value);
+
+            $blacklist{$md5sum} = {
+                'sha1'   => $sha1,
+                'sha256' => $sha256,
+                'name'   => $name,
+                'link'   => $link,
+            };
+        }
+
+        return \%blacklist;
+    }
+);
+
+# known good files
+has LENNA_WHITELIST => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->load('files/banned/lenna/whitelist');
+    }
+);
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /\bimage\b/i
+      || $item->file_type =~ /^Matlab v\d+ mat/i
+      || $item->file_type =~ /\bbitmap\b/i
+      || $item->file_type =~ /^PDF Document\b/i
+      || $item->file_type =~ /^Postscript Document\b/i;
+
+    return
+      if $self->LENNA_WHITELIST->recognizes($item->md5sum);
+
+    # Lena Soderberg image
+    $self->pointed_hint('license-problem-non-free-img-lenna', $item->pointer)
+      if $item->basename =~ / ( \b | _ ) lenn?a ( \b | _ ) /ix
+      || exists $self->LENNA_BLACKLIST->{$item->md5sum};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Bugs.pm b/lib/Lintian/Check/Files/Bugs.pm
new file mode 100644
index 0000000..69432de
--- /dev/null
+++ b/lib/Lintian/Check/Files/Bugs.pm
@@ -0,0 +1,50 @@
+# files/bugs -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Bugs;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_dir;
+
+    $self->pointed_hint('package-contains-bts-control-dir', $item->pointer)
+      if $item->name =~ m{/\.(?:be|ditrack)/?$};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/BuildPath.pm b/lib/Lintian/Check/Files/BuildPath.pm
new file mode 100644
index 0000000..e6c73af
--- /dev/null
+++ b/lib/Lintian/Check/Files/BuildPath.pm
@@ -0,0 +1,55 @@
+# files/build-path -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::BuildPath;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    my $BUILD_PATH_REGEX
+      = $self->data->load('files/build-path-regex', qr/~~~~~/);
+
+    for my $pattern ($BUILD_PATH_REGEX->all) {
+
+        $self->pointed_hint('dir-or-file-in-build-tree', $item->pointer)
+          if $item->name =~ m{$pattern}xms
+          && $self->processable->source_name ne 'sbuild'
+          && $self->processable->source_name ne 'pbuilder';
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Compressed.pm b/lib/Lintian/Check/Files/Compressed.pm
new file mode 100644
index 0000000..d64807f
--- /dev/null
+++ b/lib/Lintian/Check/Files/Compressed.pm
@@ -0,0 +1,80 @@
+# files/compressed -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Compressed;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $VERTICAL_BAR => q{|};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# an OR (|) regex of all compressed extension
+has COMPRESS_FILE_EXTENSIONS_OR_ALL => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $COMPRESS_FILE_EXTENSIONS
+          = $self->data->load('files/compressed-file-extensions',qr/\s+/);
+
+        my $text = join($VERTICAL_BAR,
+            map { quotemeta }$COMPRESS_FILE_EXTENSIONS->all);
+
+        return qr/$text/;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    my $regex = $self->COMPRESS_FILE_EXTENSIONS_OR_ALL;
+
+    # see tag duplicated-compressed-file
+    my $DUPLICATED_COMPRESSED_FILE_REGEX= qr/^(.+)\.$regex$/;
+
+    # both compressed and uncompressed present
+    if ($item->name =~ $DUPLICATED_COMPRESSED_FILE_REGEX) {
+
+        $self->pointed_hint('compressed-duplicate', $item->pointer)
+          if $self->processable->installed->lookup($1);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Compressed/Bz2.pm b/lib/Lintian/Check/Files/Compressed/Bz2.pm
new file mode 100644
index 0000000..25c8bc1
--- /dev/null
+++ b/lib/Lintian/Check/Files/Compressed/Bz2.pm
@@ -0,0 +1,57 @@
+# files/compressed/bz2 -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Compressed::Bz2;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    if ($item->name =~ /\.bz2$/si) {
+
+        safe_qx('bzip2', '--test', $item->unpacked_path);
+
+        $self->pointed_hint('broken-bz2', $item->pointer)
+          if $?;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Compressed/Gz.pm b/lib/Lintian/Check/Files/Compressed/Gz.pm
new file mode 100644
index 0000000..6290247
--- /dev/null
+++ b/lib/Lintian/Check/Files/Compressed/Gz.pm
@@ -0,0 +1,113 @@
+# files/compressed/gz -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Compressed::Gz;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Time::Piece;
+
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# get timestamp of first member; https://tools.ietf.org/html/rfc1952.html#page-5
+const my $GZIP_HEADER_SIZE => 8;
+
+has changelog_timestamp => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        # remains 0 if there is no timestamp
+        my $changelog = $self->processable->changelog;
+        if (defined $changelog) {
+
+            my ($entry) = @{$changelog->entries};
+            return $entry->Timestamp
+              if $entry && $entry->Timestamp;
+        }
+
+        return 0;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    if ($item->name =~ /\.gz$/si) {
+
+        safe_qx('gzip', '--test', $item->unpacked_path);
+
+        $self->pointed_hint('broken-gz', $item->pointer)
+          if $?;
+    }
+
+    # gzip files
+    if ($item->file_type =~ /gzip compressed/) {
+
+        my $bytes = $item->magic($GZIP_HEADER_SIZE);
+        my (undef, $gziptime) = unpack('VV', $bytes);
+
+        if (defined $gziptime && $gziptime != 0) {
+
+            # see https://bugs.debian.org/762105
+            my $time_from_build = $gziptime - $self->changelog_timestamp;
+            if ($time_from_build > 0) {
+
+                my $architecture
+                  = $self->processable->fields->value('Architecture');
+                my $multiarch
+                  = $self->processable->fields->value('Multi-Arch') || 'no';
+
+                if ($multiarch eq 'same' && $item->name !~ /\Q$architecture\E/)
+                {
+                    $self->pointed_hint(
+                        'gzip-file-is-not-multi-arch-same-safe',
+                        $item->pointer);
+
+                } else {
+                    $self->pointed_hint('package-contains-timestamped-gzip',
+                        $item->pointer,gmtime($gziptime)->datetime);
+                }
+            }
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Compressed/Lz.pm b/lib/Lintian/Check/Files/Compressed/Lz.pm
new file mode 100644
index 0000000..defed97
--- /dev/null
+++ b/lib/Lintian/Check/Files/Compressed/Lz.pm
@@ -0,0 +1,77 @@
+# files/compressed/lz -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Chris Lamb
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Compressed::Lz;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(first_value);
+
+use Lintian::IPC::Run3 qw(safe_qx);
+use Lintian::Util qw(locate_executable);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has lzip_command => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $command = first_value { locate_executable($_) } qw(lzip clzip);
+
+        return $command;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    my $command = $self->lzip_command;
+    return
+      unless length $command;
+
+    if ($item->name =~ /\.lz$/si) {
+
+        safe_qx($command, '--test', $item->unpacked_path);
+
+        $self->pointed_hint('broken-lz', $item->pointer)
+          if $?;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Compressed/Lzma.pm b/lib/Lintian/Check/Files/Compressed/Lzma.pm
new file mode 100644
index 0000000..2f49853
--- /dev/null
+++ b/lib/Lintian/Check/Files/Compressed/Lzma.pm
@@ -0,0 +1,57 @@
+# files/compressed/lzma -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Compressed::Lzma;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    if ($item->name =~ /\.lzma$/si) {
+
+        safe_qx('lzma', '--test', $item->unpacked_path);
+
+        $self->pointed_hint('broken-lzma', $item->pointer)
+          if $?;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Compressed/Lzo.pm b/lib/Lintian/Check/Files/Compressed/Lzo.pm
new file mode 100644
index 0000000..5e6cdca
--- /dev/null
+++ b/lib/Lintian/Check/Files/Compressed/Lzo.pm
@@ -0,0 +1,57 @@
+# files/compressed/lzo -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Compressed::Lzo;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    if ($item->name =~ /\.lzo$/si) {
+
+        safe_qx('lzop', '--test', $item->unpacked_path);
+
+        $self->pointed_hint('broken-lzo', $item->pointer)
+          if $?;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Compressed/Xz.pm b/lib/Lintian/Check/Files/Compressed/Xz.pm
new file mode 100644
index 0000000..6f3c6a0
--- /dev/null
+++ b/lib/Lintian/Check/Files/Compressed/Xz.pm
@@ -0,0 +1,57 @@
+# files/compressed/xz -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Compressed::Xz;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    if ($item->name =~ /\.xz$/si) {
+
+        safe_qx('xz', '--test', $item->unpacked_path);
+
+        $self->pointed_hint('broken-xz', $item->pointer)
+          if $?;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Compressed/Zip.pm b/lib/Lintian/Check/Files/Compressed/Zip.pm
new file mode 100644
index 0000000..68b9395
--- /dev/null
+++ b/lib/Lintian/Check/Files/Compressed/Zip.pm
@@ -0,0 +1,62 @@
+# files/compressed/zip -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Compressed::Zip;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    if ($item->name =~ /\.zip$/si) {
+
+        # maybe rewrite with Archive::Zip
+
+        # may prompt for password with -t; piping yes '' does not work
+        safe_qx('unzip', '-l', $item->unpacked_path);
+
+        $self->pointed_hint('broken-zip', $item->pointer)
+          if $?;
+
+        # should issue a tag for encrypted members, see Bug#935292
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/ConfigScripts.pm b/lib/Lintian/Check/Files/ConfigScripts.pm
new file mode 100644
index 0000000..b5df56c
--- /dev/null
+++ b/lib/Lintian/Check/Files/ConfigScripts.pm
@@ -0,0 +1,108 @@
+# files/config-scripts -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::ConfigScripts;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::SlidingWindow;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    my $architecture = $self->processable->fields->value('Architecture');
+    my $multiarch = $self->processable->fields->value('Multi-Arch') || 'no';
+
+    # check old style config scripts
+    if (   $item->name =~ m{^usr/bin/}
+        && $item->name =~ m/-config$/
+        && $item->is_script
+        && $item->is_regular_file) {
+
+        # try to find some indication of
+        # config file (read only one block)
+
+        open(my $fd, '<:raw', $item->unpacked_path)
+          or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+        my $sfd = Lintian::SlidingWindow->new;
+        $sfd->handle($fd);
+
+        my $block = $sfd->readwindow;
+
+        # some common stuff found in config file
+        if (
+            $block
+            && (   $block =~ / flag /msx
+                || $block =~ m{ /include/ }msx
+                || $block =~ / pkg-config /msx)
+        ) {
+
+            $self->pointed_hint('old-style-config-script', $item->pointer);
+
+            # could be ok but only if multi-arch: no
+            if ($multiarch ne 'no' || $architecture eq 'all') {
+
+                # check multi-arch path
+                my $DEB_HOST_MULTIARCH
+                  = $self->data->architectures->deb_host_multiarch;
+                for my $madir (values %{$DEB_HOST_MULTIARCH}) {
+
+                    next
+                      unless $block =~ m{\W\Q$madir\E(\W|$)}xms;
+
+                    # allow files to begin with triplet if it matches arch
+                    next
+                      if $item->basename =~ m{^\Q$madir\E}xms;
+
+                    my $tag_name = 'old-style-config-script-multiarch-path';
+                    $tag_name .= '-arch-all'
+                      if $architecture eq 'all';
+
+                    $self->pointed_hint($tag_name, $item->pointer,
+                        'full text contains architecture specific dir',$madir);
+
+                    last;
+                }
+            }
+        }
+
+        close $fd;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Contents.pm b/lib/Lintian/Check/Files/Contents.pm
new file mode 100644
index 0000000..472c419
--- /dev/null
+++ b/lib/Lintian/Check/Files/Contents.pm
@@ -0,0 +1,150 @@
+# files/contents -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Contents;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $SLASH => q{/};
+const my $ARROW => q{ -> };
+
+my $SENSIBLE_REGEX
+  = qr{(?<!-)(?:select-editor|sensible-(?:browser|editor|pager))\b};
+
+# with this Moo default, maintainer scripts are also checked
+has switched_locations => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my @files
+          = grep { $_->is_file } @{$self->processable->installed->sorted_list};
+
+        my @commands = grep { $_->name =~ m{^(?:usr/)?s?bin/} } @files;
+
+        my %switched_locations;
+        for my $command (@commands) {
+
+            my @variants = map { $_ . $SLASH . $command->basename }
+              qw(bin sbin usr/bin usr/sbin);
+            my @confused = grep { $_ ne $command->name } @variants;
+
+            $switched_locations{$_} = $command->name for @confused;
+        }
+
+        return \%switched_locations;
+    }
+);
+
+sub build_path {
+    my ($self) = @_;
+
+    my $buildinfo = $self->group->buildinfo;
+
+    return $EMPTY
+      unless $buildinfo;
+
+    return $buildinfo->fields->value('Build-Path');
+}
+
+sub check_item {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    unless ($self->processable->relation('all')->satisfies('sensible-utils')
+        || $self->processable->source_name eq 'sensible-utils') {
+
+        my $sensible = $item->mentions_in_operation($SENSIBLE_REGEX);
+        $self->pointed_hint('missing-depends-on-sensible-utils',
+            $item->pointer, $sensible)
+          if length $sensible;
+    }
+
+    unless ($self->processable->fields->value('Section') eq 'debian-installer'
+        || any { $_ eq $self->processable->source_name } qw(base-files dpkg)) {
+
+        $self->pointed_hint('uses-dpkg-database-directly', $item->pointer)
+          if length $item->mentions_in_operation(qr{/var/lib/dpkg});
+    }
+
+    # if we have a /usr/sbin/foo, check for references to /usr/bin/foo
+    my %switched_locations = %{$self->switched_locations};
+    for my $confused (keys %switched_locations) {
+
+  # may not work as expected on ELF due to ld's SHF_MERGE
+  # but word boundaries are also superior in strings spanning multiple commands
+        my $correct = $switched_locations{$confused};
+        $self->pointed_hint('bin-sbin-mismatch', $item->pointer,
+            $confused . $ARROW . $correct)
+          if length $item->mentions_in_operation(qr{ \B / \Q$confused\E \b }x);
+    }
+
+    if (length $self->build_path) {
+        my $escaped_path = quotemeta($self->build_path);
+        $self->pointed_hint('file-references-package-build-path',
+            $item->pointer)
+          if $item->bytes_match(qr{$escaped_path});
+    }
+
+    return;
+}
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    $self->check_item($item);
+
+    return;
+}
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_maintainer_script;
+
+    $self->check_item($item);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Contents/LineLength.pm b/lib/Lintian/Check/Files/Contents/LineLength.pm
new file mode 100644
index 0000000..63f38ca
--- /dev/null
+++ b/lib/Lintian/Check/Files/Contents/LineLength.pm
@@ -0,0 +1,140 @@
+# files/contents/line-length -- lintian check script -*- perl -*-
+
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Contents::LineLength;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::UtilsBy qw(max_by);
+use Unicode::UTF8 qw(encode_utf8 decode_utf8 valid_utf8);
+
+const my $GREATER_THAN => q{>};
+const my $VERTICAL_BAR => q{|};
+
+const my $VERY_LONG => 512;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# an OR (|) regex of all compressed extension
+has BINARY_FILE_EXTENSIONS_OR_ALL => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $BINARY_FILE_EXTENSIONS
+          = $self->data->load('files/binary-file-extensions',qr/\s+/);
+        my $COMPRESSED_FILE_EXTENSIONS
+          = $self->data->load('files/compressed-file-extensions',qr/\s+/);
+
+        my $text = join(
+            $VERTICAL_BAR,
+            (
+                map { quotemeta } $BINARY_FILE_EXTENSIONS->all,
+                $COMPRESSED_FILE_EXTENSIONS->all
+            )
+        );
+
+        return qr/$text/i;
+    }
+);
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    # Skip if no regular file
+    return
+      unless $item->is_regular_file;
+
+    # Skip if file has a known binary, XML or JSON suffix.
+    my $pattern = $self->BINARY_FILE_EXTENSIONS_OR_ALL;
+    return
+      if $item->basename
+      =~ qr{ [.] ($pattern | xml | sgml | svg | jsonl?) \s* $}x;
+
+    # Skip if we can't open it.
+    return
+      unless $item->is_open_ok;
+
+    # Skip if file is a REUSE license (LICENSES/**.txt), which are
+    # canonically provided with long lines rather than being hard-wrapped.
+    return
+      if $item->name =~ m{^ LICENSES/ .* [.] txt $}x;
+
+    # Skip if file is detected to be an image or JSON.
+    return
+      if $item->file_type =~ m{image|bitmap|JSON};
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my %line_lengths;
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+        # Skip SQL insert and select statements
+        next if ($line =~ /^(INSERT|SELECT)\s/i
+            and $item->basename =~ /sql/i);
+
+        # count codepoints, if possible
+        $line = decode_utf8($line)
+          if valid_utf8($line);
+
+        $line_lengths{$position} = length $line;
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    my $longest = max_by { $line_lengths{$_} } keys %line_lengths;
+
+    return
+      unless defined $longest;
+
+    my $pointer = $item->pointer($longest);
+
+    $self->pointed_hint('very-long-line-length-in-source-file',
+        $pointer, $line_lengths{$longest}, $GREATER_THAN, $VERY_LONG)
+      if $line_lengths{$longest} > $VERY_LONG;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Date.pm b/lib/Lintian/Check/Files/Date.pm
new file mode 100644
index 0000000..3b1f479
--- /dev/null
+++ b/lib/Lintian/Check/Files/Date.pm
@@ -0,0 +1,66 @@
+# files/date -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Date;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# value from dak CVS: Dinstall::PastCutOffYear
+const my $DINSTALL_CUTOFF_YEAR => 1975;
+
+has ALLOWED_ANCIENT_FILES => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->load('files/allowed-ancient-files');
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    my ($year) = ($item->date =~ /^(\d{4})/);
+
+    $self->pointed_hint('package-contains-ancient-file',
+        $item->pointer, $item->date)
+      if $year <= $DINSTALL_CUTOFF_YEAR
+      && !$self->ALLOWED_ANCIENT_FILES->matches_any($item->name);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Debug.pm b/lib/Lintian/Check/Files/Debug.pm
new file mode 100644
index 0000000..9eead27
--- /dev/null
+++ b/lib/Lintian/Check/Files/Debug.pm
@@ -0,0 +1,55 @@
+# files/debug -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Debug;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has warned_already => (is => 'rw', default => 0);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    if ($item->name =~ m{^usr/lib/debug/\S}) {
+
+        $self->pointed_hint('debug-suffix-not-dbg', $item->pointer)
+          if !$self->processable->is_debug_package
+          && !$self->warned_already;
+
+        $self->warned_already(1);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/DebugPackages.pm b/lib/Lintian/Check/Files/DebugPackages.pm
new file mode 100644
index 0000000..7f83816
--- /dev/null
+++ b/lib/Lintian/Check/Files/DebugPackages.pm
@@ -0,0 +1,50 @@
+# files/debug-packages -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::DebugPackages;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    $self->pointed_hint('non-debug-file-in-debug-package', $item->pointer)
+      if $item->is_file
+      && $item->name !~ /\.debug$/
+      && $self->processable->is_debug_package
+      && $self->processable->is_auto_generated;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Desktop.pm b/lib/Lintian/Check/Files/Desktop.pm
new file mode 100644
index 0000000..fca3006
--- /dev/null
+++ b/lib/Lintian/Check/Files/Desktop.pm
@@ -0,0 +1,57 @@
+# files/desktop -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Desktop;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # .desktop files
+    # People have placed them everywhere, but nowadays the
+    # consensus seems to be to stick to the fd.org standard
+    # drafts, which says that .desktop files intended for
+    # menus should be placed in $XDG_DATA_DIRS/applications.
+    # The default for $XDG_DATA_DIRS is
+    # /usr/local/share/:/usr/share/, according to the
+    # basedir-spec on fd.org. As distributor, we should only
+    # allow /usr/share.
+
+    $self->pointed_hint('desktop-file-in-wrong-dir', $item->pointer)
+      if $item->name =~ m{^usr/share/gnome/apps/.*\.desktop$};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Duplicates.pm b/lib/Lintian/Check/Files/Duplicates.pm
new file mode 100644
index 0000000..b1dc809
--- /dev/null
+++ b/lib/Lintian/Check/Files/Duplicates.pm
@@ -0,0 +1,88 @@
+# files/duplicates -- lintian check script -*- perl -*-
+
+# Copyright (C) 2011 Niels Thykier
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Duplicates;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(any);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has md5map => (is => 'rw', default => sub{ {} });
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_regular_file;
+
+    # Ignore empty files; in some cases (e.g. python) a file is
+    # required even if it is empty and we are never looking at a
+    # substantial gain in such a case.  Also see #632789
+    return
+      unless $item->size;
+
+    my $calculated = $item->md5sum;
+    return
+      unless defined $calculated;
+
+    return
+      unless $item->name =~ m{\A usr/share/doc/}xsm;
+
+    $self->md5map->{$calculated} //= [];
+
+    push(@{$self->md5map->{$calculated}}, $item);
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    for my $md5 (keys %{$self->md5map}){
+        my @files = @{ $self->md5map->{$md5} };
+
+        next
+          if scalar @files < 2;
+
+        if (any { m/changelog/i} @files) {
+            $self->hint('duplicate-changelog-files', (sort @files));
+
+        } else {
+            $self->hint('duplicate-files', (sort @files));
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/EmptyDirectories.pm b/lib/Lintian/Check/Files/EmptyDirectories.pm
new file mode 100644
index 0000000..52079cb
--- /dev/null
+++ b/lib/Lintian/Check/Files/EmptyDirectories.pm
@@ -0,0 +1,67 @@
+# files/empty-directories -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::EmptyDirectories;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_dir;
+
+    # skip base-files, which is a very special case.
+    return
+      if $self->processable->name eq 'base-files';
+
+    # ignore /var, which may hold dynamic data packages create, and /etc,
+    # which may hold configuration files generated by maintainer scripts
+    return
+      if $item->name =~ m{^var/} || $item->name =~ m{^etc/};
+
+    # Empty Perl directories are an ExtUtils::MakeMaker artifact that
+    # will be fixed in Perl 5.10, and people can cause more problems
+    # by trying to fix it, so just ignore them.
+    return
+      if $item->name =~ m{^usr/lib/(?:[^/]+/)?perl5/$}
+      || $item->name eq 'usr/share/perl5/';
+
+    # warn about empty directories
+    $self->pointed_hint('package-contains-empty-directory', $item->pointer)
+      if scalar $item->children == 0;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/EmptyPackage.pm b/lib/Lintian/Check/Files/EmptyPackage.pm
new file mode 100644
index 0000000..5b23846
--- /dev/null
+++ b/lib/Lintian/Check/Files/EmptyPackage.pm
@@ -0,0 +1,159 @@
+# files/empty-package -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2019 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::EmptyPackage;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# Common files stored in /usr/share/doc/$pkg that aren't sufficient to
+# consider the package non-empty.
+has STANDARD_FILES => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->load('files/standard-files');
+    }
+);
+
+has is_empty => (is => 'rw', default => 1);
+has is_dummy => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        # check if package is empty
+        return 1
+          if $self->processable->is_transitional
+          || $self->processable->is_meta_package;
+
+        return 0;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $self->is_empty;
+
+    return
+      if $self->is_dummy;
+
+    # ignore directories
+    return
+      if $item->is_dir;
+
+    my $pkg = $self->processable->name;
+    my $ppkg = quotemeta($self->processable->name);
+
+    # skip if file is outside /usr/share/doc/$pkg directory
+    if ($item->name !~ m{^usr/share/doc/\Q$pkg\E}) {
+
+        # - except if it is a lintian override.
+        return
+          if $item->name =~ m{\A
+                             # Except for:
+                             usr/share/ (?:
+                                 # lintian overrides
+                                 lintian/overrides/$ppkg(?:\.gz)?
+                                 # reportbug scripts/utilities
+                             | bug/$ppkg(?:/(?:control|presubj|script))?
+                             )\Z}xsm;
+
+        $self->is_empty(0);
+
+        return;
+    }
+
+    # skip if /usr/share/doc/$pkg has files in a subdirectory
+    if ($item->name =~ m{^usr/share/doc/\Q$pkg\E/[^/]+/}) {
+
+        $self->is_empty(0);
+
+        return;
+    }
+
+    # skip /usr/share/doc/$pkg symlinks.
+    return
+      if $item->name eq "usr/share/doc/$pkg";
+
+    # For files directly in /usr/share/doc/$pkg, if the
+    # file isn't one of the uninteresting ones, the
+    # package isn't empty.
+    return
+      if $self->STANDARD_FILES->recognizes($item->basename);
+
+    # ignore all READMEs
+    return
+      if $item->basename =~ m/^README(?:\..*)?$/i;
+
+    my $pkg_arch = $self->processable->architecture;
+    unless ($pkg_arch eq 'all') {
+
+        # binNMU changelog (debhelper)
+        return
+          if $item->basename eq "changelog.Debian.${pkg_arch}.gz";
+    }
+
+    # buildinfo file (dh-buildinfo)
+    return
+      if $item->basename eq "buildinfo_${pkg_arch}.gz";
+
+    $self->is_empty(0);
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    return
+      if $self->is_dummy;
+
+    if ($self->is_empty) {
+
+        $self->hint('empty-binary-package')
+          if $self->processable->type eq 'binary';
+
+        $self->hint('empty-udeb-package')
+          if $self->processable->type eq 'udeb';
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Encoding.pm b/lib/Lintian/Check/Files/Encoding.pm
new file mode 100644
index 0000000..f175401
--- /dev/null
+++ b/lib/Lintian/Check/Files/Encoding.pm
@@ -0,0 +1,125 @@
+# files/encoding -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Encoding;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use IO::Uncompress::Gunzip qw(gunzip $GunzipError);
+use Unicode::UTF8 qw(valid_utf8 encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->name =~ m{^debian/};
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /text$/;
+
+    if ($item->name =~ m{^debian/patches/}) {
+
+        my $bytes = $item->bytes;
+        return
+          unless length $bytes;
+
+        my ($header)= split(/^---/m, $bytes, 2);
+
+        $self->pointed_hint('national-encoding', $item->pointer,'DEP-3 header')
+          unless valid_utf8($header);
+
+    } else {
+        $self->pointed_hint('national-encoding', $item->pointer)
+          unless $item->is_valid_utf8;
+    }
+
+    return;
+}
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /text$/ || $item->is_script;
+
+    $self->pointed_hint('national-encoding', $item->pointer)
+      unless $item->is_valid_utf8;
+
+    return;
+}
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # this checks debs; most other nat'l encoding tags are for source
+    # Bug#796170 also suggests limiting paths and including gzip files
+
+    # return
+    #   unless $item->name =~ m{^(?:usr/)?s?bin/}
+    #   || $item->name =~ m{^usr/games/}
+    #   || $item->name =~ m{\.(?:p[myl]|php|rb|tcl|sh|txt)(?:\.gz)?$}
+    #   || $item->name =~ m{^usr/share/doc};
+
+    if ($item->file_type =~ /text$/) {
+
+        $self->pointed_hint('national-encoding', $item->pointer)
+          unless $item->is_valid_utf8;
+    }
+
+    # for man pages also look at compressed files
+    if (   $item->name =~ m{^usr/share/man/}
+        && $item->file_type =~ /gzip compressed/) {
+
+        my $bytes;
+
+        my $path = $item->unpacked_path;
+        gunzip($path => \$bytes)
+          or die encode_utf8("gunzip $path failed: $GunzipError");
+
+        $self->pointed_hint('national-encoding', $item->pointer)
+          unless valid_utf8($bytes);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Generated.pm b/lib/Lintian/Check/Files/Generated.pm
new file mode 100644
index 0000000..35c88d5
--- /dev/null
+++ b/lib/Lintian/Check/Files/Generated.pm
@@ -0,0 +1,83 @@
+# files/generated -- lintian check script -*- perl -*-
+
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Generated;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+const my $DOUBLE_QUOTE => q{"};
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    # check all patched source files except the Debian patches
+    return
+      if $item->name =~ m{^ debian/patches/ }x;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        if ($line
+            =~m{ ( This [ ] file [ ] (?: is | was ) [ ] autogenerated ) }xi
+            || $line
+            =~ m{ ( DO [ ] NOT [ ] EDIT [ ] (?: THIS [ ] FILE [ ] )? BY [ ] HAND ) }xi
+        ) {
+
+            my $marker = $1;
+
+            $self->pointed_hint(
+                'generated-file',
+                $item->pointer($position),
+                $DOUBLE_QUOTE . $marker . $DOUBLE_QUOTE
+            );
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/HardLinks.pm b/lib/Lintian/Check/Files/HardLinks.pm
new file mode 100644
index 0000000..f115897
--- /dev/null
+++ b/lib/Lintian/Check/Files/HardLinks.pm
@@ -0,0 +1,57 @@
+# files/hard-links -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::HardLinks;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_hardlink;
+
+    my $target_dir = $item->link;
+    $target_dir =~ s{[^/]*$}{};
+
+    # link always sorts after target; hard links are calibrated
+    $self->pointed_hint('package-contains-hardlink', $item->pointer,
+        'pointing to:', $item->link)
+      if $item->name =~ m{^etc/}
+      || $item->link =~ m{^etc/}
+      || $item->name !~ m{^\Q$target_dir\E[^/]*$};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Hierarchy/Links.pm b/lib/Lintian/Check/Files/Hierarchy/Links.pm
new file mode 100644
index 0000000..2402b5d
--- /dev/null
+++ b/lib/Lintian/Check/Files/Hierarchy/Links.pm
@@ -0,0 +1,83 @@
+# files/symbolic-links/broken -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2020 Felix Lechner
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Hierarchy::Links;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use File::Basename;
+use List::SomeUtils qw(any first_value);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $SLASH => q{/};
+const my $ARROW => q{ -> };
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # symbolic links only
+    return
+      unless $item->is_symlink;
+
+    my $target = $item->link_normalized;
+    return
+      unless defined $target;
+
+    my @ldconfig_folders = @{$self->data->architectures->ldconfig_folders};
+
+    my $origin_dirname= first_value { $item->dirname eq $_ } @ldconfig_folders;
+
+    # look only at links originating in common ld.so load paths
+    return
+      unless length $origin_dirname;
+
+    my $target_dirname
+      = first_value { (dirname($target) . $SLASH) eq $_ } @ldconfig_folders;
+    $target_dirname //= $EMPTY;
+
+    # no subfolders
+    $self->pointed_hint('ldconfig-escape', $item->pointer, $target)
+      unless length $target_dirname;
+
+    my @multiarch= values %{$self->data->architectures->deb_host_multiarch};
+
+    $self->pointed_hint('architecture-escape', $item->pointer,  $target)
+      if (any { basename($origin_dirname) eq $_ } @multiarch)
+      && (any { $target_dirname eq "$_/" } qw{lib usr/lib usr/local/lib});
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Hierarchy/MergedUsr.pm b/lib/Lintian/Check/Files/Hierarchy/MergedUsr.pm
new file mode 100644
index 0000000..ebd0d1c
--- /dev/null
+++ b/lib/Lintian/Check/Files/Hierarchy/MergedUsr.pm
@@ -0,0 +1,48 @@
+# files/hierarchy/merged-usr -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Hierarchy::MergedUsr;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    $self->pointed_hint('unmerged-usr', $item->pointer)
+      if $item->is_file
+      && $item->name =~ m{^(?:lib|bin|sbin)};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Hierarchy/PathSegments.pm b/lib/Lintian/Check/Files/Hierarchy/PathSegments.pm
new file mode 100644
index 0000000..b9e5535
--- /dev/null
+++ b/lib/Lintian/Check/Files/Hierarchy/PathSegments.pm
@@ -0,0 +1,57 @@
+# files/hierarchy/path-segments -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Hierarchy::PathSegments;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_dir;
+
+    my @segments = split(m{/}, $item->name);
+    return
+      unless @segments;
+
+    my $final = $segments[-1];
+    my $count = scalar grep { $final eq $_ } @segments;
+
+    $self->pointed_hint('repeated-path-segment', $item->pointer, $final)
+      if $count > 1;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Hierarchy/Standard.pm b/lib/Lintian/Check/Files/Hierarchy/Standard.pm
new file mode 100644
index 0000000..e00955b
--- /dev/null
+++ b/lib/Lintian/Check/Files/Hierarchy/Standard.pm
@@ -0,0 +1,262 @@
+# files/hierarchy/standard -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Hierarchy::Standard;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub _is_tmp_path {
+    my ($path) = @_;
+
+    return 1
+      if $path =~ m{^tmp/.}
+      || $path =~ m{^(?:var|usr)/tmp/.}
+      || $path =~ m{^/dev/shm/};
+
+    return 0;
+}
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    if ($item->name =~ m{^etc/opt/.}) {
+
+        # /etc/opt
+        $self->pointed_hint('dir-or-file-in-etc-opt', $item->pointer);
+
+    } elsif ($item->name =~ m{^usr/local/\S+}) {
+        # /usr/local
+        if ($item->is_dir) {
+            $self->pointed_hint('dir-in-usr-local', $item->pointer);
+        } else {
+            $self->pointed_hint('file-in-usr-local', $item->pointer);
+        }
+
+    } elsif ($item->name =~ m{^usr/share/[^/]+$}) {
+        # /usr/share
+        $self->pointed_hint('file-directly-in-usr-share', $item->pointer)
+          if $item->is_file;
+
+    } elsif ($item->name =~ m{^usr/bin/}) {
+        # /usr/bin
+        $self->pointed_hint('subdir-in-usr-bin', $item->pointer)
+          if $item->is_dir
+          && $item->name =~ m{^usr/bin/.}
+          && $item->name !~ m{^usr/bin/(?:X11|mh)/};
+
+    } elsif ($self->processable->type ne 'udeb'
+        && $item->name =~ m{^usr/[^/]+/$}) {
+
+        # /usr subdirs
+        if ($item->name=~ m{^usr/(?:dict|doc|etc|info|man|adm|preserve)/}) {
+            # FSSTND dirs
+            $self->pointed_hint('FSSTND-dir-in-usr', $item->pointer);
+        } elsif (
+            $item->name !~ m{^usr/(?:X11R6|X386|
+                                    bin|games|include|
+                                    lib|
+                                    local|sbin|share|
+                                    src|spool|tmp)/}x
+        ) {
+            # FHS dirs
+            if ($item->name =~ m{^usr/lib(?<libsuffix>64|x?32)/}) {
+                my $libsuffix = $+{libsuffix};
+                # eglibc exception is due to FHS. Other are
+                # transitional, waiting for full
+                # implementation of multi-arch.  Note that we
+                # allow (e.g.) "lib64" packages to still use
+                # these dirs, since their use appears to be by
+                # intention.
+                unless ($self->processable->source_name =~ m/^e?glibc$/
+                    or $self->processable->name =~ m/^lib$libsuffix/) {
+
+                    $self->pointed_hint('non-multi-arch-lib-dir',
+                        $item->pointer);
+                }
+            } else {
+                # see Bug#834607
+                $self->pointed_hint('non-standard-dir-in-usr', $item->pointer)
+                  unless $item->name =~ m{^usr/libexec/};
+            }
+
+        }
+
+        # unless $item =~ m,^usr/[^/]+-linuxlibc1/,; was tied
+        # into print above...
+        # Make an exception for the altdev dirs, which will go
+        # away at some point and are not worth moving.
+    }
+
+    # /var subdirs
+    elsif ($self->processable->type ne 'udeb'
+        && $item->name =~ m{^var/[^/]+/$}) {
+
+        if ($item->name =~ m{^var/(?:adm|catman|named|nis|preserve)/}) {
+            # FSSTND dirs
+            $self->pointed_hint('FSSTND-dir-in-var', $item->pointer);
+
+        } elsif ($self->processable->name eq 'base-files'
+            && $item->name =~ m{^var/(?:backups|local)/}) {
+            # base-files is special
+            # ignore
+
+        } elsif (
+            $item->name !~ m{\A var/
+                             (?: account|lib|cache|crash|games
+                                |lock|log|opt|run|spool|state
+                                |tmp|www|yp)/
+             }xsm
+        ) {
+            # FHS dirs with exception in Debian policy
+            $self->pointed_hint('non-standard-dir-in-var', $item->pointer);
+        }
+
+    } elsif ($self->processable->type ne 'udeb'
+        && $item->name =~ m{^var/lib/games/.}) {
+        $self->pointed_hint('non-standard-dir-in-var', $item->pointer);
+
+    } elsif ($self->processable->type ne 'udeb'
+        && $item->name =~ m{^var/lock/.}) {
+        # /var/lock
+        $self->pointed_hint('dir-or-file-in-var-lock', $item->pointer);
+
+    } elsif ($self->processable->type ne 'udeb'
+        && $item->name =~ m{^var/run/.}) {
+        # /var/run
+        $self->pointed_hint('dir-or-file-in-var-run', $item->pointer);
+
+    } elsif ($self->processable->type ne 'udeb' && $item->name =~ m{^run/.}) {
+        $self->pointed_hint('dir-or-file-in-run', $item->pointer);
+
+    } elsif ($item->name =~ m{^var/www/\S+}) {
+        # /var/www
+        # Packages are allowed to create /var/www since it's
+        # historically been the default document root, but they
+        # shouldn't be installing stuff under that directory.
+        $self->pointed_hint('dir-or-file-in-var-www', $item->pointer);
+
+    } elsif ($item->name =~ m{^opt/.}) {
+        # /opt
+        $self->pointed_hint('dir-or-file-in-opt', $item->pointer);
+
+    } elsif ($item->name =~ m{^hurd/}) {
+        return;
+
+    } elsif ($item->name =~ m{^servers/}) {
+        return;
+
+    } elsif ($item->name =~ m{^home/.}) {
+        # /home
+        $self->pointed_hint('dir-or-file-in-home', $item->pointer);
+
+    } elsif ($item->name =~ m{^root/.}) {
+        $self->pointed_hint('dir-or-file-in-home', $item->pointer);
+
+    } elsif (_is_tmp_path($item->name)) {
+        # /tmp, /var/tmp, /usr/tmp
+        $self->pointed_hint('dir-or-file-in-tmp', $item->pointer);
+
+    } elsif ($item->name =~ m{^mnt/.}) {
+        # /mnt
+        $self->pointed_hint('dir-or-file-in-mnt', $item->pointer);
+
+    } elsif ($item->name =~ m{^bin/}) {
+        # /bin
+        $self->pointed_hint('subdir-in-bin', $item->pointer)
+          if $item->is_dir && $item->name =~ m{^bin/.};
+
+    } elsif ($item->name =~ m{^srv/.}) {
+        # /srv
+        $self->pointed_hint('dir-or-file-in-srv', $item->pointer);
+
+    }elsif (
+        $item->name =~ m{^[^/]+/$}
+        && $item->name !~ m{\A (?:
+                  bin|boot|dev|etc|home|lib
+                 |mnt|opt|root|run|sbin|srv|sys
+                 |tmp|usr|var)  /
+          }xsm
+    ) {
+        # FHS directory?
+
+        # Make an exception for the base-files package here and
+        # other similar packages because they install a slew of
+        # top-level directories for setting up the base system.
+        # (Specifically, /cdrom, /floppy, /initrd, and /proc are
+        # not mentioned in the FHS).
+        if ($item->name =~ m{^lib(?<libsuffix>64|x?32)/}) {
+            my $libsuffix = $+{libsuffix};
+
+            # see comments for ^usr/lib(?'libsuffix'64|x?32)
+            $self->pointed_hint('non-multi-arch-lib-dir', $item->pointer)
+              unless $self->processable->source_name =~ m/^e?glibc$/
+              || $self->processable->name =~ m/^lib$libsuffix/;
+
+        } else {
+            $self->pointed_hint('non-standard-toplevel-dir', $item->pointer)
+              unless $self->processable->name eq 'base-files'
+              || $self->processable->name eq 'hurd'
+              || $self->processable->name eq 'hurd-udeb'
+              || $self->processable->name =~ /^rootskel(?:-bootfloppy)?/;
+        }
+    }
+
+    # compatibility symlinks should not be used
+    $self->pointed_hint('use-of-compat-symlink', $item->pointer)
+      if $item->name =~ m{^usr/(?:spool|tmp)/}
+      || $item->name =~ m{^usr/(?:doc|bin)/X11/}
+      || $item->name =~ m{^var/adm/};
+
+    # any files
+    $self->pointed_hint('file-in-unusual-dir', $item->pointer)
+      unless $item->is_dir
+      || $self->processable->type eq 'udeb'
+      || $item->name =~ m{^usr/(?:bin|dict|doc|games|
+                                    include|info|lib(?:x?32|64)?|
+                                    man|sbin|share|src|X11R6)/}x
+      || $item->name =~ m{^lib(?:x?32|64)?/(?:modules/|libc5-compat/)?}
+      || $item->name =~ m{^var/(?:games|lib|www|named)/}
+      || $item->name =~ m{^(?:bin|boot|dev|etc|sbin)/}
+      # non-FHS, but still usual
+      || $item->name =~ m{^usr/[^/]+-linux[^/]*/}
+      || $item->name =~ m{^usr/libexec/} # FHS 3.0 / #834607
+      || $item->name =~ m{^usr/iraf/}
+      # not allowed, but tested individually
+      || $item->name =~ m{\A (?:
+                        build|home|mnt|opt|root|run|srv
+                       |(?:(?:usr|var)/)?tmp)|var/www/}xsm;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/IeeeData.pm b/lib/Lintian/Check/Files/IeeeData.pm
new file mode 100644
index 0000000..0c2ba68
--- /dev/null
+++ b/lib/Lintian/Check/Files/IeeeData.pm
@@ -0,0 +1,79 @@
+# files/ieee-data -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::IeeeData;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $VERTICAL_BAR => q{|};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# an OR (|) regex of all compressed extension
+has COMPRESS_FILE_EXTENSIONS_OR_ALL => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $COMPRESS_FILE_EXTENSIONS
+          = $self->data->load('files/compressed-file-extensions',qr/\s+/);
+
+        my $text = join($VERTICAL_BAR,
+            map { quotemeta }$COMPRESS_FILE_EXTENSIONS->all);
+
+        return qr/$text/;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    my $regex = $self->COMPRESS_FILE_EXTENSIONS_OR_ALL;
+
+    if (   $item->is_regular_file
+        && $item->name
+        =~ m{/(?:[^/]-)?(?:oui|iab)(?:\.(txt|idx|db))?(?:\.$regex)?\Z}x) {
+
+        # see #785662
+        if ($item->name =~ / oui /msx || $item->name =~ / iab /msx) {
+
+            $self->pointed_hint('package-installs-ieee-data', $item->pointer)
+              unless $self->processable->source_name eq 'ieee-data';
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Includes.pm b/lib/Lintian/Check/Files/Includes.pm
new file mode 100644
index 0000000..ec10bb8
--- /dev/null
+++ b/lib/Lintian/Check/Files/Includes.pm
@@ -0,0 +1,69 @@
+# files/includes -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Includes;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw{any};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# case insensitive regular expressions for overly generic paths
+const my @GENERIC_PATHS => ('^ util[s]? [.]h $');
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    my $consumed = $item->name;
+    return
+      unless $consumed =~ s{^usr/include/}{};
+
+    my @multiarch_folders
+      = values %{$self->data->architectures->deb_host_multiarch};
+
+    for my $tuple (@multiarch_folders) {
+
+        last
+          if $consumed =~ s{^$tuple/}{};
+    }
+
+    $self->pointed_hint('header-has-overly-generic-name', $item->pointer)
+      if any { $consumed =~ m{ $_ }isx } @GENERIC_PATHS;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Init.pm b/lib/Lintian/Check/Files/Init.pm
new file mode 100644
index 0000000..25ff77d
--- /dev/null
+++ b/lib/Lintian/Check/Files/Init.pm
@@ -0,0 +1,79 @@
+# files/init -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Init;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(none);
+
+const my $NOT_EQUAL => q{!=};
+
+const my $EXECUTABLE_PERMISSIONS => oct(755);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # /etc/init
+    $self->pointed_hint('package-installs-deprecated-upstart-configuration',
+        $item->pointer)
+      if $item->name =~ m{^etc/init/\S};
+
+    # /etc/init.d
+    $self->pointed_hint(
+        'non-standard-file-permissions-for-etc-init.d-script',
+        $item->pointer,
+        $item->octal_permissions,
+        $NOT_EQUAL,
+        sprintf('%04o', $EXECUTABLE_PERMISSIONS)
+      )
+      if $item->name =~ m{^etc/init\.d/\S}
+      && $item->name !~ m{^etc/init\.d/(?:README|skeleton)$}
+      && $item->operm != $EXECUTABLE_PERMISSIONS
+      && $item->is_file;
+
+    # /etc/rc.d && /etc/rc?.d
+    $self->pointed_hint('package-installs-into-etc-rc.d', $item->pointer)
+      if $item->name =~ m{^etc/rc(?:\d|S)?\.d/\S}
+      && (none { $self->processable->name eq $_ } qw(sysvinit file-rc))
+      && $self->processable->type ne 'udeb';
+
+    # /etc/rc.boot
+    $self->pointed_hint('package-installs-into-etc-rc.boot', $item->pointer)
+      if $item->name =~ m{^etc/rc\.boot/\S};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/LdSo.pm b/lib/Lintian/Check/Files/LdSo.pm
new file mode 100644
index 0000000..2f0b9c1
--- /dev/null
+++ b/lib/Lintian/Check/Files/LdSo.pm
@@ -0,0 +1,48 @@
+# files/ld-so -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::LdSo;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    $self->pointed_hint('package-modifies-ld.so-search-path', $item->pointer)
+      if $item->name =~ m{^etc/ld\.so\.conf\.d/.+$}
+      && $self->processable->name !~ /^libc/;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Licenses.pm b/lib/Lintian/Check/Files/Licenses.pm
new file mode 100644
index 0000000..5ca61e4
--- /dev/null
+++ b/lib/Lintian/Check/Files/Licenses.pm
@@ -0,0 +1,112 @@
+# files/licenses -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Licenses;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # license files
+    if (
+        $item->basename =~ m{ \A
+                # Look for commonly used names for license files
+                (?: copying | licen[cs]e | l?gpl | bsd | artistic )
+                # ... possibly followed by a version
+                [v0-9._-]*
+                (?:\. .* )? \Z
+                }xsmi
+        # Ignore some common extensions for source or compiled
+        # extension files.  There was at least one file named
+        # "license.el".  These are probably license-displaying
+        # code, not license files.  Also ignore executable files
+        # in general. This means we get false-negatives for
+        # licenses files marked executable, but these will trigger
+        # a warning about being executable. (See #608866)
+        #
+        # Another exception is made for .html and .php because
+        # preserving working links is more important than saving
+        # some bytes, and because a package had an HTML form for
+        # licenses called like that.  Another exception is made
+        # for various picture formats since those are likely to
+        # just be simply pictures.
+        #
+        # DTD files are excluded at the request of the Mozilla
+        # suite maintainers.  Zope products include license files
+        # for runtime display.  underXXXlicense.docbook files are
+        # from KDE.
+        #
+        # Ignore extra license files in examples, since various
+        # package building software includes example packages with
+        # licenses.
+        && !$item->is_executable
+        && $item->name !~ m{ \. (?:
+                  # Common "non-license" file extensions...
+                   el|[ch]|cc|p[ylmc]|[hu]i|p_hi|html|php|rb|xpm
+                     |png|jpe?g|gif|svg|dtd|mk|lisp|yml|rs|ogg|xbm
+               ) \Z}xsm
+        && $item->name !~ m{^usr/share/zope/Products/.*\.(?:dtml|pt|cpt)$}
+        && $item->name !~ m{/under\S+License\.docbook$}
+        && $item->name !~ m{^usr/share/doc/[^/]+/examples/}
+        # liblicense has a manpage called license
+        && $item->name !~ m{^usr/share/man/(?:[^/]+/)?man\d/}
+        # liblicense (again)
+        && $item->name !~ m{^usr/share/pyshared-data/}
+        # Rust crate unmodified upstream sources
+        && $item->name !~ m{^usr/share/cargo/registry/}
+        # Some GNOME/GTK software uses these to show the "license
+        # header".
+        && $item->name !~ m{
+               ^usr/share/(?:gnome/)?help/[^/]+/[^/]+/license\.page$
+             }x
+        # base-files (which is required to ship them)
+        && $item->name !~ m{^usr/share/common-licenses/[^/]+$}
+        && !length($item->link)
+        # Sphinx includes various license files
+        && $item->name !~ m{/_sources/license(?:\.rst)?\.txt$}i
+    ) {
+
+        # okay, we cannot rule it out based on file name; but if
+        # it is an elf or a static library, we also skip it.  (In
+        # case you hadn't guessed; liblicense)
+
+        $self->pointed_hint('extra-license-file', $item->pointer)
+          unless $item->file_type =~ m/^[^,]*\bELF\b/
+          || $item->file_type =~ m/\bcurrent ar archive\b/;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Locales.pm b/lib/Lintian/Check/Files/Locales.pm
new file mode 100644
index 0000000..e645a83
--- /dev/null
+++ b/lib/Lintian/Check/Files/Locales.pm
@@ -0,0 +1,204 @@
+# files/locales -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2013 Niels Thykier <niels@thykier.net>
+# Copyright (C) 2019 Adam D. Barratt <adam@adam-barratt.org.uk>
+# Copyright (C) 2021 Felix Lechner
+#
+# Based in part on a shell script that was:
+#   Copyright (C) 2010 Raphael Geissert <atomo64@gmail.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Locales;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use JSON::MaybeXS;
+use List::SomeUtils qw(first_value);
+use Path::Tiny;
+
+const my $EMPTY => q{};
+
+const my $ARROW => q{->};
+
+const my $RESERVED => $EMPTY;
+const my $SPECIAL => q{S};
+
+const my %CONFUSING_LANGUAGES => (
+    # Albanian is sq, not al:
+    'al' => 'sq',
+    # Chinese is zh, not cn:
+    'cn' => 'zh',
+    # Czech is cs, not cz:
+    'cz' => 'cs',
+    # Danish is da, not dk:
+    'dk' => 'da',
+    # Greek is el, not gr:
+    'gr' => 'el',
+    # Indonesian is id, not in:
+    'in' => 'id',
+);
+
+const my %CONFUSING_COUNTRIES => (
+    # UK != GB
+    'en_UK' => 'en_GB',
+);
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has ISO639_3_by_alpha3 => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        local $ENV{LC_ALL} = 'C';
+
+        my $bytes = path('/usr/share/iso-codes/json/iso_639-3.json')->slurp;
+        my $json = decode_json($bytes);
+
+        my %iso639_3;
+        for my $entry (@{$json->{'639-3'}}) {
+
+            my $alpha_3 = $entry->{alpha_3};
+
+            $iso639_3{$alpha_3} = $entry;
+        }
+
+        return \%iso639_3;
+    }
+);
+
+has LOCALE_CODES => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        local $ENV{LC_ALL} = 'C';
+
+        my %CODES;
+        for my $entry (values %{$self->ISO639_3_by_alpha3}) {
+
+            my $type = $entry->{type};
+
+            # https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=692548#10
+            next
+              if $type eq $RESERVED || $type eq $SPECIAL;
+
+            # also have two letters, ISO 639-1
+            my $two_letters;
+            $two_letters = $entry->{alpha_2}
+              if exists $entry->{alpha_2};
+
+            $CODES{$two_letters} = $EMPTY
+              if length $two_letters;
+
+            # three letters, ISO 639-2
+            my $three_letters = $entry->{alpha_3};
+
+            # a value indicates that two letters are preferred
+            $CODES{$three_letters} = $two_letters || $EMPTY;
+        }
+
+        return \%CODES;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_dir;
+
+    return
+      unless $item->name =~ m{^ usr/share/locale/ ([^/]+) / $}x;
+
+    my $folder = $1;
+
+    # without encoding
+    my ($with_country) = split(m/[.@]/, $folder);
+
+    # special exception
+    return
+      if $with_country eq 'l10n';
+
+    # without country code
+    my ($two_or_three, $country) = split(m/_/, $with_country);
+
+    $country //= $EMPTY;
+
+    return
+      unless length $two_or_three;
+
+    # check some common language errors
+    if (exists $CONFUSING_LANGUAGES{$two_or_three}) {
+
+        my $fixed = $folder;
+        $fixed =~ s{^ $two_or_three }{$CONFUSING_LANGUAGES{$two_or_three}}x;
+
+        $self->pointed_hint('incorrect-locale-code', $item->pointer, $folder,
+            $ARROW,$fixed);
+        return;
+    }
+
+    # check some common country errors
+    if (exists $CONFUSING_COUNTRIES{$with_country}) {
+
+        my $fixed = $folder;
+        $fixed =~ s{^ $with_country }{$CONFUSING_COUNTRIES{$with_country}}x;
+
+        $self->pointed_hint('incorrect-locale-code', $item->pointer, $folder,
+            $ARROW,$fixed);
+        return;
+    }
+
+    # check known codes
+    if (exists $self->LOCALE_CODES->{$two_or_three}) {
+
+        my $replacement = $self->LOCALE_CODES->{$two_or_three};
+        return
+          unless length $replacement;
+
+        # a value indicates that two letters are preferred
+        my $fixed = $folder;
+        $fixed =~ s{^ $two_or_three }{$replacement}x;
+
+        $self->pointed_hint('incorrect-locale-code', $item->pointer, $folder,
+            $ARROW,$fixed);
+
+        return;
+    }
+
+    $self->pointed_hint('unknown-locale-code', $item->pointer, $folder);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Missing.pm b/lib/Lintian/Check/Files/Missing.pm
new file mode 100644
index 0000000..4c6eda5
--- /dev/null
+++ b/lib/Lintian/Check/Files/Missing.pm
@@ -0,0 +1,50 @@
+# files/missing -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Missing;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    if (   $item->is_dir
+        && $item->faux) {
+
+        $self->pointed_hint('missing-intermediate-directory', $item->pointer);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/MultiArch.pm b/lib/Lintian/Check/Files/MultiArch.pm
new file mode 100644
index 0000000..5d6a2f0
--- /dev/null
+++ b/lib/Lintian/Check/Files/MultiArch.pm
@@ -0,0 +1,111 @@
+# files/multi-arch -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::MultiArch;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has TRIPLETS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $DEB_HOST_MULTIARCH= $self->data->architectures->deb_host_multiarch;
+        my %triplets = map { $DEB_HOST_MULTIARCH->{$_} => $_ }
+          keys %{$DEB_HOST_MULTIARCH};
+
+        return \%triplets;
+    }
+);
+
+my %PATH_DIRECTORIES = map { $_ => 1 } qw(
+  bin/ sbin/ usr/bin/ usr/sbin/ usr/games/ );
+
+has has_public_executable => (is => 'rw', default => 0);
+has has_public_shared_library => (is => 'rw', default => 0);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    my $architecture = $self->processable->fields->value('Architecture');
+    my $multiarch = $self->processable->fields->value('Multi-Arch') || 'no';
+
+    my $DEB_HOST_MULTIARCH= $self->data->architectures->deb_host_multiarch;
+    my $multiarch_dir = $DEB_HOST_MULTIARCH->{$architecture};
+
+    if (   !$item->is_dir
+        && defined $multiarch_dir
+        && $multiarch eq 'foreign'
+        && $item->name =~ m{^usr/lib/\Q$multiarch_dir\E/(.*)$}) {
+
+        my $tail = $1;
+
+        $self->pointed_hint('multiarch-foreign-cmake-file', $item->pointer)
+          if $tail =~ m{^cmake/.+\.cmake$};
+
+        $self->pointed_hint('multiarch-foreign-pkgconfig', $item->pointer)
+          if $tail =~ m{^pkgconfig/[^/]+\.pc$};
+
+        $self->pointed_hint('multiarch-foreign-static-library', $item->pointer)
+          if $tail =~ m{^lib[^/]+\.a$};
+    }
+
+    if (exists($PATH_DIRECTORIES{$item->dirname})) {
+        $self->has_public_executable(1);
+    }
+
+    if ($item->name =~ m{^(?:usr/)?lib/(?:([^/]+)/)?lib[^/]*\.so$}) {
+        $self->has_public_shared_library(1)
+          if (!defined($1) || exists $self->TRIPLETS->{$1});
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $architecture = $self->processable->fields->value('Architecture');
+    my $multiarch = $self->processable->fields->value('Multi-Arch') || 'no';
+
+    $self->hint('multiarch-foreign-shared-library')
+      if $architecture ne 'all'
+      and $multiarch eq 'foreign'
+      and $self->has_public_shared_library
+      and not $self->has_public_executable;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Names.pm b/lib/Lintian/Check/Files/Names.pm
new file mode 100644
index 0000000..a6b022c
--- /dev/null
+++ b/lib/Lintian/Check/Files/Names.pm
@@ -0,0 +1,163 @@
+# files/names -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Names;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::Compare;
+use Unicode::UTF8 qw(valid_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+my %PATH_DIRECTORIES = map { $_ => 1 } qw(
+  bin/ sbin/ usr/bin/ usr/sbin/ usr/games/ );
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # unusual characters
+    $self->pointed_hint('file-name-ends-in-whitespace', $item->pointer)
+      if $item->name =~ /\s+\z/;
+
+    $self->pointed_hint('star-file', $item->pointer)
+      if $item->name =~ m{/\*\z};
+
+    $self->pointed_hint('hyphen-file', $item->pointer)
+      if $item->name =~ m{/-\z};
+
+    $self->pointed_hint('file-name-contains-wildcard-character',$item->pointer)
+      if $item->name =~ m{[*?]};
+
+    $self->pointed_hint('package-contains-compiled-glib-schema',$item->pointer)
+      if $item->name
+      =~ m{^ usr/share/ glib-[^/]+ /schemas/ gschemas[.]compiled $}x;
+
+    $self->pointed_hint('package-contains-file-in-etc-skel', $item->pointer)
+      if $item->dirname =~ m{^etc/skel/}
+      && $item->basename
+      !~ m{^ [.]bashrc | [.]bash_logout | [.]m?kshrc | [.]profile $}x;
+
+    $self->pointed_hint('package-contains-file-in-usr-share-hal',
+        $item->pointer)
+      if $item->dirname =~ m{^usr/share/hal/};
+
+    $self->pointed_hint('package-contains-icon-cache-in-generic-dir',
+        $item->pointer)
+      if $item->name eq 'usr/share/icons/hicolor/icon-theme.cache';
+
+    $self->pointed_hint('package-contains-python-dot-directory',$item->pointer)
+      if $item->dirname
+      =~ m{^ usr/lib/python[^/]+ / (?:dist|site)-packages / }x
+      && $item->name =~ m{ / [.][^/]+ / }x;
+
+    $self->pointed_hint('package-contains-python-coverage-file',$item->pointer)
+      if $item->basename eq '.coverage';
+
+    $self->pointed_hint('package-contains-python-doctree-file', $item->pointer)
+      if $item->basename =~ m{ [.]doctree (?:[.]gz)? $}x;
+
+    $self->pointed_hint(
+        'package-contains-python-header-in-incorrect-directory',
+        $item->pointer)
+      if $item->dirname =~ m{^ usr/include/python3[.][01234567]/ }x
+      && $item->name =~ m{ [.]h $}x;
+
+    $self->pointed_hint('package-contains-python-hypothesis-example',
+        $item->pointer)
+      if $item->dirname =~ m{ /[.]hypothesis/examples/ }x;
+
+    $self->pointed_hint('package-contains-python-tests-in-global-namespace',
+        $item->pointer)
+      if $item->name
+      =~ m{^ usr/lib/python[^\/]+ / (?:dist|site)-packages / test_.+[.]py $}x;
+
+    $self->pointed_hint('package-contains-sass-cache-directory',$item->pointer)
+      if $item->name =~ m{ / [.]sass-cache / }x;
+
+    $self->pointed_hint('package-contains-eslint-config-file', $item->pointer)
+      if $item->basename =~ m{^ [.]eslintrc }x;
+
+    $self->pointed_hint('package-contains-npm-ignore-file', $item->pointer)
+      if $item->basename eq '.npmignore';
+
+    if (exists($PATH_DIRECTORIES{$item->dirname})) {
+
+        $self->pointed_hint('file-name-in-PATH-is-not-ASCII', $item->pointer)
+          if $item->basename !~ m{\A [[:ascii:]]++ \Z}xsm;
+
+        $self->pointed_hint('zero-byte-executable-in-path', $item->pointer)
+          if $item->is_regular_file
+          and $item->is_executable
+          and $item->size == 0;
+
+    } elsif (!valid_utf8($item->name)) {
+        $self->pointed_hint('shipped-file-without-utf8-name', $item->pointer);
+    }
+
+    return;
+}
+
+sub source {
+    my ($self) = @_;
+
+    unless ($self->processable->native) {
+
+        my @orig_non_utf8 = grep { !valid_utf8($_->name) }
+          @{$self->processable->orig->sorted_list};
+
+        $self->pointed_hint('upstream-file-without-utf8-name', $_->pointer)
+          for @orig_non_utf8;
+    }
+
+    my @patched = map { $_->name } @{$self->processable->patched->sorted_list};
+    my @orig = map { $_->name } @{$self->processable->orig->sorted_list};
+
+    my $lc= List::Compare->new(\@patched, \@orig);
+    my @created = $lc->get_Lonly;
+
+    my @non_utf8 = grep { !valid_utf8($_) } @created;
+
+    # exclude quilt directory
+    my @maintainer_fault = grep { !m{^.pc/} } @non_utf8;
+
+    if ($self->processable->native) {
+        $self->hint('native-source-file-without-utf8-name', $_)
+          for @maintainer_fault;
+
+    } else {
+        $self->hint('patched-file-without-utf8-name', $_)for @maintainer_fault;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/NonFree.pm b/lib/Lintian/Check/Files/NonFree.pm
new file mode 100644
index 0000000..32e5e7f
--- /dev/null
+++ b/lib/Lintian/Check/Files/NonFree.pm
@@ -0,0 +1,142 @@
+# files/non-free -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::NonFree;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any);
+use Unicode::UTF8 qw(encode_utf8);
+
+const my $MD5SUM_DATA_FIELDS => 5;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub _md5sum_based_lintian_data {
+    my ($self, $filename) = @_;
+
+    my $data = $self->data->load($filename,qr/\s*\~\~\s*/);
+
+    my %md5sum_data;
+
+    for my $md5sum ($data->all) {
+
+        my $value = $data->value($md5sum);
+
+        my ($sha1, $sha256, $name, $reason, $link)
+          = split(/ \s* ~~ \s* /msx, $value, $MD5SUM_DATA_FIELDS);
+
+        die encode_utf8("Syntax error in $filename $.")
+          if any { !defined } ($sha1, $sha256, $name, $reason, $link);
+
+        $md5sum_data{$md5sum} = {
+            'sha1'   => $sha1,
+            'sha256' => $sha256,
+            'name'   => $name,
+            'reason' => $reason,
+            'link'   => $link,
+        };
+    }
+
+    return \%md5sum_data;
+}
+
+has NON_FREE_FILES => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->_md5sum_based_lintian_data('cruft/non-free-files');
+    }
+);
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # skip packages that declare non-free contents
+    return
+      if $self->processable->is_non_free;
+
+    my $nonfree = $self->NON_FREE_FILES->{$item->md5sum};
+    if (defined $nonfree) {
+        my $usualname = $nonfree->{'name'};
+        my $reason = $nonfree->{'reason'};
+        my $link = $nonfree->{'link'};
+
+        $self->pointed_hint(
+            'license-problem-md5sum-non-free-file',
+            $item->pointer, "usual name is $usualname.",
+            $reason, "See also $link."
+        );
+    }
+
+    return;
+}
+
+# A list of known non-free flash executables
+my @flash_nonfree = (
+    qr/(?i)dewplayer(?:-\w+)?\.swf$/,
+    qr/(?i)(?:mp3|flv)player\.swf$/,
+    # Situation needs to be clarified:
+    #    qr,(?i)multipleUpload\.swf$,
+    #    qr,(?i)xspf_jukebox\.swf$,
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # skip packages that declare non-free contents
+    return
+      if $self->processable->is_non_free;
+
+    # non-free .swf files
+    $self->pointed_hint('non-free-flash', $item->pointer)
+      if any { $item->name =~ m{/$_} } @flash_nonfree;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/ObsoletePaths.pm b/lib/Lintian/Check/Files/ObsoletePaths.pm
new file mode 100644
index 0000000..b1d2ddd
--- /dev/null
+++ b/lib/Lintian/Check/Files/ObsoletePaths.pm
@@ -0,0 +1,92 @@
+# files/obsolete-paths -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::ObsoletePaths;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has OBSOLETE_PATHS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %obsolete;
+
+        my $data = $self->data->load('files/obsolete-paths',qr/\s*\->\s*/);
+
+        for my $key ($data->all) {
+
+            my $value = $data->value($key);
+
+            my ($newdir, $moreinfo) = split(/\s*\~\~\s*/, $value, 2);
+
+            $obsolete{$key} = {
+                'newdir' => $newdir,
+                'moreinfo' => $moreinfo,
+                'match' => qr/$key/x,
+                'olddir' => $key,
+            };
+        }
+
+        return \%obsolete;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # check for generic obsolete path
+    for my $obsolete_path (keys %{$self->OBSOLETE_PATHS}) {
+
+        my $obs_data = $self->OBSOLETE_PATHS->{$obsolete_path};
+        my $oldpathmatch = $obs_data->{'match'};
+
+        if ($item->name =~ m{$oldpathmatch}) {
+
+            my $oldpath  = $obs_data->{'olddir'};
+            my $newpath  = $obs_data->{'newdir'};
+            my $moreinfo = $obs_data->{'moreinfo'};
+
+            $self->pointed_hint('package-installs-into-obsolete-dir',
+                $item->pointer,": $oldpath -> $newpath", $moreinfo);
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Openpgp.pm b/lib/Lintian/Check/Files/Openpgp.pm
new file mode 100644
index 0000000..dc421df
--- /dev/null
+++ b/lib/Lintian/Check/Files/Openpgp.pm
@@ -0,0 +1,51 @@
+# files/openpgp -- lintian check script -*- perl -*-
+
+# Copyright (C) 2022 Guillem Jover <guillem@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Openpgp;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    $self->pointed_hint('openpgp-file-has-implementation-specific-extension',
+        $item->pointer)
+      if $item->name =~ m{\.gpg$};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Ownership.pm b/lib/Lintian/Check/Files/Ownership.pm
new file mode 100644
index 0000000..bbea4b9
--- /dev/null
+++ b/lib/Lintian/Check/Files/Ownership.pm
@@ -0,0 +1,74 @@
+# files/ownership -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Ownership;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SLASH => q{/};
+
+const my $MAXIMUM_LOW_RESERVED => 99;
+const my $MAXIMUM_HIGH_RESERVED => 64_999;
+const my $MINIMUM_HIGH_RESERVED => 60_000;
+const my $NOBODY => 65_534;
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    $self->pointed_hint('wrong-file-owner-uid-or-gid', $item->pointer,
+        $item->uid . $SLASH . $item->gid)
+      if out_of_bounds($item->uid)
+      || out_of_bounds($item->gid);
+
+    return;
+}
+
+sub out_of_bounds {
+    my ($id) = @_;
+
+    return 0
+      if $id <= $MAXIMUM_LOW_RESERVED;
+
+    return 0
+      if $id == $NOBODY;
+
+    return 0
+      if $id >= $MINIMUM_HIGH_RESERVED
+      && $id <= $MAXIMUM_HIGH_RESERVED;
+
+    return 1;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/P11Kit.pm b/lib/Lintian/Check/Files/P11Kit.pm
new file mode 100644
index 0000000..a128fa0
--- /dev/null
+++ b/lib/Lintian/Check/Files/P11Kit.pm
@@ -0,0 +1,54 @@
+# files/p11-kit -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::P11Kit;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    if (
+        $item->name =~ m{^usr/share/p11-kit/modules/.}
+        && $item->name !~ m{\A usr/share/p11-kit/modules/
+                       [[:alnum:]][[:alnum:]_.-]*\.module\Z
+                  }xsm
+    ) {
+        $self->pointed_hint('incorrect-naming-of-pkcs11-module',
+            $item->pointer);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Pam.pm b/lib/Lintian/Check/Files/Pam.pm
new file mode 100644
index 0000000..c02cd4b
--- /dev/null
+++ b/lib/Lintian/Check/Files/Pam.pm
@@ -0,0 +1,50 @@
+# files/pam -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Pam;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # /etc/pam.conf
+    $self->pointed_hint('config-file-reserved', $item->pointer,
+        'by libpam-runtime')
+      if $item->name =~ m{^etc/pam.conf$}
+      && $self->processable->name ne 'libpam-runtime';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Permissions.pm b/lib/Lintian/Check/Files/Permissions.pm
new file mode 100644
index 0000000..30cff5b
--- /dev/null
+++ b/lib/Lintian/Check/Files/Permissions.pm
@@ -0,0 +1,249 @@
+# files/permissions -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Permissions;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Path::Tiny;
+
+const my $NOT_EQUAL => q{!=};
+
+const my $STANDARD_EXECUTABLE => oct(755);
+const my $SETGID_EXECUTABLE => oct(4754);
+const my $SET_USER_ID => oct(4000);
+const my $SET_GROUP_ID => oct(2000);
+
+const my $STANDARD_FILE => oct(644);
+const my $BACKUP_NINJA_FILE => oct(600);
+const my $SUDOERS_FILE => oct(440);
+const my $GAME_DATA => oct(664);
+
+const my $STANDARD_FOLDER => oct(755);
+const my $GAME_FOLDER => oct(2775);
+const my $VAR_LOCAL_FOLDER => oct(2775);
+const my $VAR_LOCK_FOLDER => oct(1777);
+const my $USR_SRC_FOLDER => oct(2775);
+
+const my $WORLD_READABLE => oct(444);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has component => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return path($self->processable->path)->basename;
+    }
+);
+
+has linked_against_libvga => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %linked_against_libvga;
+
+        for my $item (@{$self->processable->installed->sorted_list}) {
+
+            for my $library (@{$item->elf->{NEEDED} // []}){
+
+                $linked_against_libvga{$item->name} = 1
+                  if $library =~ m{^ libvga[.]so[.] }x;
+            }
+        }
+
+        return \%linked_against_libvga;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    if ($item->is_file) {
+
+        if (
+            $item->is_executable
+            && $item->identity eq 'root/games'
+            && (   !$item->is_setgid
+                || !$item->all_bits_set($STANDARD_EXECUTABLE))
+        ) {
+
+            $self->pointed_hint(
+                'non-standard-game-executable-perm',
+                $item->pointer,
+                $item->octal_permissions,
+                $NOT_EQUAL,
+                sprintf('%04o', $SET_GROUP_ID | $STANDARD_EXECUTABLE)
+            );
+
+            return;
+        }
+
+        $self->pointed_hint('executable-is-not-world-readable',
+            $item->pointer, $item->octal_permissions)
+          if $item->is_executable
+          && !$item->all_bits_set($WORLD_READABLE);
+
+        if ($item->is_setuid || $item->is_setgid) {
+
+            $self->pointed_hint('non-standard-setuid-executable-perm',
+                $item->pointer, $item->octal_permissions)
+              unless (($item->operm & ~($SET_USER_ID | $SET_GROUP_ID))
+                == $STANDARD_EXECUTABLE)
+              || $item->operm == $SETGID_EXECUTABLE;
+        }
+
+        # allow anything with suid in the name
+        return
+          if ($item->is_setuid || $item->is_setgid)
+          && $self->processable->name =~ / -suid /msx;
+
+        # program is using svgalib
+        return
+          if $item->is_setuid
+          && !$item->is_setgid
+          && $item->owner eq 'root'
+          && exists $self->linked_against_libvga->{$item->name};
+
+        # program is a setgid game
+        return
+          if $item->is_setgid
+          && !$item->is_setuid
+          && $item->group eq 'games'
+          && $item->name =~ m{^ usr/ (?:lib/)? games/ \S+ }msx;
+
+        if ($item->is_setuid || $item->is_setgid) {
+            $self->pointed_hint(
+                'elevated-privileges', $item->pointer,
+                $item->octal_permissions, $item->identity
+            );
+
+            return;
+        }
+
+        if (   $item->is_executable
+            && $item->operm != $STANDARD_EXECUTABLE) {
+
+            $self->pointed_hint('non-standard-executable-perm',
+                $item->pointer, $item->octal_permissions, $NOT_EQUAL,
+                sprintf('%04o', $STANDARD_EXECUTABLE));
+
+            return;
+        }
+
+        if (!$item->is_executable) {
+
+            # game data
+            return
+              if $item->operm == $GAME_DATA
+              && $item->identity eq 'root/games'
+              && $item->name =~ m{^ var/ (?:lib/)? games/ \S+ }msx;
+
+            # GNAT compiler wants read-only Ada library information.
+            if (   $item->name =~ m{^ usr/lib/ .* [.]ali $}msx
+                && $item->operm != $WORLD_READABLE) {
+
+                $self->pointed_hint('bad-permissions-for-ali-file',
+                    $item->pointer);
+
+                return;
+            }
+
+            # backupninja expects configurations files to be oct(600)
+            return
+              if $item->operm == $BACKUP_NINJA_FILE
+              && $item->name =~ m{^ etc/backup.d/ }msx;
+
+            if ($item->name =~ m{^ etc/sudoers.d/ }msx) {
+
+                # sudo requires sudoers files to be mode oct(440)
+                $self->pointed_hint(
+                    'bad-perm-for-file-in-etc-sudoers.d',$item->pointer,
+                    $item->octal_permissions, $NOT_EQUAL,
+                    sprintf('%04o', $SUDOERS_FILE)
+                )unless $item->operm == $SUDOERS_FILE;
+
+                return;
+            }
+
+            $self->pointed_hint(
+                'non-standard-file-perm', $item->pointer,
+                $item->octal_permissions, $NOT_EQUAL,
+                sprintf('%04o', $STANDARD_FILE)
+            )unless $item->operm == $STANDARD_FILE;
+        }
+
+    }
+
+    if ($item->is_dir) {
+
+        # game directory with setgid bit
+        return
+          if $item->operm == $GAME_FOLDER
+          && $item->identity eq 'root/games'
+          && $item->name =~ m{^ var/ (?:lib/)? games/ \S+ }msx;
+
+        # shipping files here triggers warnings elsewhere
+        return
+          if $item->operm == $VAR_LOCK_FOLDER
+          && $item->identity eq 'root/root'
+          && ( $item->name =~ m{^ (?:var/)? tmp/ }msx
+            || $item->name eq 'var/lock/');
+
+        # shipping files here triggers warnings elsewhere
+        return
+          if $item->operm == $VAR_LOCAL_FOLDER
+          && $item->identity eq 'root/staff'
+          && $item->name eq 'var/local/';
+
+        # /usr/src created by base-files
+        return
+          if $item->operm == $USR_SRC_FOLDER
+          && $item->identity eq 'root/src'
+          && $item->name eq 'usr/src/';
+
+        $self->pointed_hint(
+            'non-standard-dir-perm', $item->pointer,
+            $item->octal_permissions, $NOT_EQUAL,
+            sprintf('%04o', $STANDARD_FOLDER)
+        )unless $item->operm == $STANDARD_FOLDER;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Permissions/UsrLib.pm b/lib/Lintian/Check/Files/Permissions/UsrLib.pm
new file mode 100644
index 0000000..e465310
--- /dev/null
+++ b/lib/Lintian/Check/Files/Permissions/UsrLib.pm
@@ -0,0 +1,54 @@
+# files/permissions/usr-lib -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Permissions::UsrLib;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # see Bug#959037 for details
+    return
+      if $self->processable->type eq 'udeb';
+
+    return
+      unless $item->name =~ m{^usr/lib/};
+
+    $self->pointed_hint('executable-in-usr-lib', $item->pointer)
+      if $item->is_file && $item->is_executable;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Pkgconfig.pm b/lib/Lintian/Check/Files/Pkgconfig.pm
new file mode 100644
index 0000000..b2d555b
--- /dev/null
+++ b/lib/Lintian/Check/Files/Pkgconfig.pm
@@ -0,0 +1,121 @@
+# files/pkgconfig -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Pkgconfig;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::SlidingWindow;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+has PKG_CONFIG_BAD_REGEX => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->load('files/pkg-config-bad-regex',qr/~~~~~/);
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    my $architecture = $self->processable->fields->value('Architecture');
+
+    # arch-indep pkgconfig
+    if (   $item->is_regular_file
+        && $item->name=~ m{^usr/(lib(/[^/]+)?|share)/pkgconfig/[^/]+\.pc$}){
+
+        my $prefix = $1;
+        my $pkg_config_arch = $2 // $EMPTY;
+        $pkg_config_arch =~ s{\A/}{}ms;
+
+        $self->pointed_hint('pkg-config-unavailable-for-cross-compilation',
+            $item->pointer)
+          if $prefix eq 'lib';
+
+        open(my $fd, '<:raw', $item->unpacked_path)
+          or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+        my $sfd = Lintian::SlidingWindow->new;
+        $sfd->handle($fd);
+
+      BLOCK:
+        while (my $block = $sfd->readwindow) {
+            # remove comment line
+            $block =~ s/\#\V*//gsm;
+            # remove continuation line
+            $block =~ s/\\\n/ /gxsm;
+            # check if pkgconfig file include path point to
+            # arch specific dir
+
+            my $DEB_HOST_MULTIARCH
+              = $self->data->architectures->deb_host_multiarch;
+            for my $madir (values %{$DEB_HOST_MULTIARCH}) {
+
+                next
+                  if $pkg_config_arch eq $madir;
+
+                if ($block =~ m{\W\Q$madir\E(\W|$)}xms) {
+
+                    $self->pointed_hint('pkg-config-multi-arch-wrong-dir',
+                        $item->pointer,
+                        'full text contains architecture specific dir',$madir);
+
+                    last;
+                }
+            }
+
+            for my $pattern ($self->PKG_CONFIG_BAD_REGEX->all) {
+
+                while($block =~ m{$pattern}xmsg) {
+
+                    my $context = $1;
+
+                    $self->pointed_hint('pkg-config-bad-directive',
+                        $item->pointer,$context);
+                }
+            }
+        }
+        close($fd);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/PrivacyBreach.pm b/lib/Lintian/Check/Files/PrivacyBreach.pm
new file mode 100644
index 0000000..8d75623
--- /dev/null
+++ b/lib/Lintian/Check/Files/PrivacyBreach.pm
@@ -0,0 +1,420 @@
+# files/privacy-breach -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::PrivacyBreach;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::SlidingWindow;
+
+const my $BLOCKSIZE => 16_384;
+const my $EMPTY => q{};
+
+const my $PRIVACY_BREAKER_WEBSITES_FIELDS => 3;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has PRIVACY_BREAKER_WEBSITES => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %website;
+
+        my $data
+          = $self->data->load('files/privacy-breaker-websites',qr/\s*\~\~/);
+
+        for my $key ($data->all) {
+
+            my $value = $data->value($key);
+
+            my ($pattern, $tag, $suggest)
+              = split(/ \s* ~~ \s* /msx,
+                $value,$PRIVACY_BREAKER_WEBSITES_FIELDS);
+
+            $tag //= $EMPTY;
+
+            # trim both ends
+            $tag =~ s/^\s+|\s+$//g;
+
+            $tag = $key
+              unless length $tag;
+
+            $website{$key} = {
+                'tag' => $tag,
+                'regexp' => qr/$pattern/xsm,
+            };
+
+            $website{$key}{'suggest'} = $suggest
+              if defined $suggest;
+        }
+
+        return \%website;
+    }
+);
+
+has PRIVACY_BREAKER_FRAGMENTS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %fragment;
+
+        my $data
+          = $self->data->load('files/privacy-breaker-fragments',qr/\s*\~\~/);
+
+        for my $key ($data->all) {
+
+            my $value = $data->value($key);
+
+            my ($pattern, $tag) = split(/\s*\~\~\s*/, $value, 2);
+
+            $fragment{$key} = {
+                'keyword' => $key,
+                'regex' => qr/$pattern/xsm,
+                'tag' => $tag,
+            };
+        }
+
+        return \%fragment;
+    }
+);
+
+has PRIVACY_BREAKER_TAG_ATTR => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %attribute;
+
+        my $data
+          = $self->data->load('files/privacy-breaker-tag-attr',qr/\s*\~\~\s*/);
+
+        for my $key ($data->all) {
+
+            my $value = $data->value($key);
+
+            my ($keywords,$pattern) = split(/\s*\~\~\s*/, $value, 2);
+
+            $pattern =~ s/&URL/(?:(?:ht|f)tps?:)?\/\/[^"\r\n]*/g;
+
+            my @keywordlist;
+
+            my @keywordsorraw = split(/\s*\|\|\s*/,$keywords);
+
+            for my $keywordor (@keywordsorraw) {
+                my @keywordsandraw = split(/\s*&&\s*/,$keywordor);
+                push(@keywordlist, \@keywordsandraw);
+            }
+
+            $attribute{$key} = {
+                'keywords' => \@keywordlist,
+                'regex' => qr/$pattern/xsm,
+            };
+        }
+
+        return \%attribute;
+    }
+);
+
+sub detect_privacy_breach {
+    my ($self, $file) = @_;
+
+    my %privacybreachhash;
+
+    return
+      unless $file->is_regular_file;
+
+    open(my $fd, '<:raw', $file->unpacked_path)
+      or die encode_utf8('Cannot open ' . $file->unpacked_path);
+
+    my $sfd = Lintian::SlidingWindow->new;
+    $sfd->handle($fd);
+    $sfd->blocksize($BLOCKSIZE);
+    $sfd->blocksub(sub { $_ = lc; });
+
+    while (my $lowercase = $sfd->readwindow) {
+        # strip comments
+        for my $x (qw(<!--(?!\[if).*?--\s*> /\*(?!@cc_on).*?\*/)) {
+            $lowercase =~ s/$x//gs;
+        }
+
+        # keep sorted; otherwise 'exists' below produces inconsistent output
+        for my $keyword (sort keys %{$self->PRIVACY_BREAKER_FRAGMENTS}) {
+
+            if ($lowercase =~ / \Q$keyword\E /msx) {
+                my $keyvalue= $self->PRIVACY_BREAKER_FRAGMENTS->{$keyword};
+                my $regex = $keyvalue->{'regex'};
+
+                if ($lowercase =~ m{($regex)}) {
+                    my $capture = $1;
+                    my $breaker_tag = $keyvalue->{'tag'};
+
+                    unless (exists $privacybreachhash{'tag-'.$breaker_tag}){
+
+                        $privacybreachhash{'tag-'.$breaker_tag} = 1;
+
+                        $self->pointed_hint($breaker_tag, $file->pointer,
+                            "(choke on: $capture)");
+                    }
+                }
+            }
+        }
+
+        for my $x (
+            qw(src="http src="ftp src="// data-href="http data-href="ftp
+            data-href="// codebase="http codebase="ftp codebase="// data="http
+            data="ftp data="// poster="http poster="ftp poster="// <link @import)
+        ) {
+            next
+              unless $lowercase =~ / \Q$x\E /msx;
+
+            $self->detect_generic_privacy_breach($lowercase,
+                \%privacybreachhash,$file);
+
+            last;
+        }
+    }
+
+    close($fd);
+    return;
+}
+
+# According to html norm src attribute is used by tags:
+#
+# audio(v5+), embed (v5+), iframe (v4), frame, img, input, script, source, track(v5), video (v5)
+# Add other tags with src due to some javascript code:
+# div due to div.js
+# div data-href due to jquery
+# css with @import
+sub detect_generic_privacy_breach {
+    my ($self, $block, $privacybreachhash, $file) = @_;
+    my %matchedkeyword;
+
+    # now check generic tag
+  TYPE:
+    for my $type (sort keys %{$self->PRIVACY_BREAKER_TAG_ATTR}) {
+        my $keyvalue = $self->PRIVACY_BREAKER_TAG_ATTR->{$type};
+        my $keywords =  $keyvalue->{'keywords'};
+
+        my $orblockok = 0;
+      ORBLOCK:
+        for my $keywordor (@{$keywords}) {
+          ANDBLOCK:
+            for my $keyword (@{$keywordor}) {
+
+                my $thiskeyword = $matchedkeyword{$keyword};
+                if(!defined($thiskeyword)) {
+                    if ($block =~ / \Q$keyword\E /msx) {
+                        $matchedkeyword{$keyword} = 1;
+                        $orblockok = 1;
+                    }else {
+                        $matchedkeyword{$keyword} = 0;
+                        $orblockok = 0;
+                        next ORBLOCK;
+                    }
+                }
+                if($matchedkeyword{$keyword} == 0) {
+                    $orblockok = 0;
+                    next ORBLOCK;
+                }else {
+                    $orblockok = 1;
+                }
+            }
+            if($orblockok == 1) {
+                last ORBLOCK;
+            }
+        }
+        if($orblockok == 0) {
+            next TYPE;
+        }
+
+        my $regex = $keyvalue->{'regex'};
+
+        while($block=~m{$regex}g){
+            $self->check_tag_url_privacy_breach($1, $2, $3,$privacybreachhash,
+                $file);
+        }
+    }
+    return;
+}
+
+sub is_localhost {
+    my ($urlshort) = @_;
+    if(    $urlshort =~ m{^(?:[^/]+@)?localhost(?:[:][^/]+)?/}i
+        || $urlshort =~ m{^(?:[^/]+@)?::1(?:[:][^/]+)?/}i
+        || $urlshort =~ m{^(?:[^/]+@)?127(?:\.\d{1,3}){3}(?:[:][^/]+)?/}i) {
+        return 1;
+    }else {
+        return 0;
+    }
+}
+
+sub check_tag_url_privacy_breach {
+    my ($self, $fulltag, $tagattr, $url,$privacybreachhash, $file) = @_;
+
+    my $website = $url;
+    # detect also "^//" trick
+    $website =~ s{^"?(?:(?:ht|f)tps?:)?//}{};
+    $website =~ s/"?$//;
+
+    if (is_localhost($website)){
+        # do nothing ok
+        return;
+    }
+
+    # reparse fulltag for rel
+    if ($tagattr eq 'link') {
+
+        my $rel = $fulltag;
+        $rel =~ m{<link
+                      (?:\s[^>]+)? \s+
+                      rel="([^"\r\n]*)"
+                      [^>]*
+                      >}xismog;
+        my $relcontent = $1;
+
+        if (defined($relcontent)) {
+            # See, for example, https://www.w3schools.com/tags/att_link_rel.asp
+            my %allowed = (
+                'alternate'         => 1, # #891301
+                'author'            => 1, # #891301
+                'bookmark'          => 1, # #746656
+                'canonical'         => 1, # #762753
+                'copyright'         => 1, # #902919
+                'edituri'           => 1, # #902919
+                'generator'         => 1, # #891301
+                'generator-home'    => 1, # texinfo
+                'help'              => 1, # #891301
+                'license'           => 1, # #891301
+                'next'              => 1, # #891301
+                'prev'              => 1, # #891301
+                'schema.dct'        => 1, # #736992
+                'search'            => 1, # #891301
+            );
+
+            return
+              if ($allowed{$relcontent});
+
+            if ($relcontent eq 'alternate') {
+                my $type = $fulltag;
+                $type =~ m{<link
+                      (?:\s[^>]+)? \s+
+                      type="([^"\r\n]*)"
+                      [^>]*
+                      >}xismog;
+                my $typecontent = $1;
+                if($typecontent eq 'application/rdf+xml') {
+                    # see #79991
+                    return;
+                }
+            }
+        }
+    }
+
+    # False positive
+    # legal.xml file of gnome
+    # could be replaced by a link to local file but not really a privacy breach
+    if(    $file->basename eq 'legal.xml'
+        && $tagattr eq 'link'
+        && $website =~ m{^creativecommons.org/licenses/}) {
+
+        return;
+    }
+
+    # In Mallard XML, <link> is a clickable anchor that will not be
+    # followed automatically.
+    if(    $file->basename =~ '.xml$'
+        && $tagattr eq 'link'
+        && $file->bytes=~ qr{ xmlns="http://projectmallard\.org/1\.0/"}) {
+
+        return;
+    }
+
+    # track well known site
+    for my $breaker (sort keys %{$self->PRIVACY_BREAKER_WEBSITES}) {
+
+        my $value = $self->PRIVACY_BREAKER_WEBSITES->{$breaker};
+        my $regex = $value->{'regexp'};
+
+        if ($website =~ m{$regex}mxs) {
+
+            unless (exists $privacybreachhash->{'tag-'.$breaker}) {
+
+                my $tag =  $value->{'tag'};
+                my $suggest = $value->{'suggest'} // $EMPTY;
+
+                $privacybreachhash->{'tag-'.$breaker}= 1;
+                $self->pointed_hint($tag, $file->pointer, $suggest, "($url)");
+            }
+
+            # do not go to generic case
+            return;
+        }
+    }
+
+    # generic case
+    unless (exists $privacybreachhash->{'tag-generic-'.$website}){
+
+        $self->pointed_hint('privacy-breach-generic', $file->pointer,
+            "[$fulltag]","($url)");
+        $privacybreachhash->{'tag-generic-'.$website} = 1;
+    }
+
+    return;
+}
+
+sub visit_installed_files {
+    my ($self, $file) = @_;
+
+    # html/javascript
+    if (   $file->is_file
+        && $file->name =~ m/\.(?:x?html?\d?|js|xht|xml|css)$/i) {
+
+        if(     $self->processable->source_name eq 'josm'
+            and $file->basename eq 'defaultpresets.xml') {
+            # false positive
+
+        } else {
+            $self->detect_privacy_breach($file);
+        }
+    }
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Scripts.pm b/lib/Lintian/Check/Files/Scripts.pm
new file mode 100644
index 0000000..3dff34e
--- /dev/null
+++ b/lib/Lintian/Check/Files/Scripts.pm
@@ -0,0 +1,57 @@
+# files/scripts -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Scripts;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # language extensions
+    if (
+        $item->name =~ m{\A
+                    (?:usr/)?(?:s?bin|games)/[^/]+\.
+                    (?:p[ly]|php|rb|[bc]?sh|tcl)
+                    \Z}xsm
+    ) {
+        $self->pointed_hint('script-with-language-extension', $item->pointer);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Sgml.pm b/lib/Lintian/Check/Files/Sgml.pm
new file mode 100644
index 0000000..fd4ace2
--- /dev/null
+++ b/lib/Lintian/Check/Files/Sgml.pm
@@ -0,0 +1,48 @@
+# files/sgml -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Sgml;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # /usr/lib/sgml
+    $self->pointed_hint('file-in-usr-lib-sgml', $item->pointer)
+      if $item->name =~ m{^usr/lib/sgml/\S};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/SourceMissing.pm b/lib/Lintian/Check/Files/SourceMissing.pm
new file mode 100644
index 0000000..6ae9f03
--- /dev/null
+++ b/lib/Lintian/Check/Files/SourceMissing.pm
@@ -0,0 +1,286 @@
+# files/source-missing -- lintian check script -*- perl -*-
+#
+# based on debhelper check,
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::SourceMissing;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use File::Basename qw(basename);
+use List::SomeUtils qw(first_value);
+use List::UtilsBy qw(max_by);
+
+# very long line lengths
+const my $VERY_LONG_LINE_LENGTH => 512;
+
+const my $EMPTY => q{};
+const my $DOLLAR => q{$};
+const my $DOT => q{.};
+const my $DOUBLE_DOT => q{..};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      if $item->dirname =~ m{^debian/missing-sources/};
+
+    # prebuilt-file or forbidden file type
+    $self->pointed_hint('source-contains-prebuilt-wasm-binary', $item->pointer)
+      if $item->file_type =~ m{^WebAssembly \s \(wasm\) \s binary \s module}x;
+
+    $self->pointed_hint('source-contains-prebuilt-windows-binary',
+        $item->pointer)
+      if $item->file_type
+      =~ m{\b(?:PE(?:32|64)|(?:MS-DOS|COM)\s executable)\b}x;
+
+    $self->pointed_hint('source-contains-prebuilt-silverlight-object',
+        $item->pointer)
+      if $item->file_type =~ m{^Zip \s archive \s data}x
+      && $item->name =~ m{(?i)\.xac$}x;
+
+    if ($item->file_type =~ m{^python \s \d(\.\d+)? \s byte-compiled}x) {
+
+        $self->pointed_hint('source-contains-prebuilt-python-object',
+            $item->pointer);
+
+        $self->pointed_hint('source-is-missing', $item->pointer)
+          unless $self->find_source($item,
+            {'.py' => '(?i)(?:\.cpython-\d{2}|\.pypy)?\.py[co]$'});
+    }
+
+    if ($item->file_type =~ m{\bELF\b}x) {
+        $self->pointed_hint('source-contains-prebuilt-binary', $item->pointer);
+
+        my %patterns = map {
+            $_  =>
+'(?i)(?:[\.-](?:bin|elf|e|hs|linux\d+|oo?|or|out|so(?:\.\d+)*)|static|_o\.golden)?$'
+        } qw(.asm .c .cc .cpp .cxx .f .F .i .ml .rc .S);
+
+        $self->pointed_hint('source-is-missing', $item->pointer)
+          unless $self->find_source($item, \%patterns);
+    }
+
+    if ($item->file_type =~ m{^Macromedia \s Flash}x) {
+
+        $self->pointed_hint('source-contains-prebuilt-flash-object',
+            $item->pointer);
+
+        $self->pointed_hint('source-is-missing', $item->pointer)
+          unless $self->find_source($item, {'.as' => '(?i)\.swf$'});
+    }
+
+    if (   $item->file_type =~ m{^Composite \s Document \s File}x
+        && $item->name =~ m{(?i)\.fla$}x) {
+
+        $self->pointed_hint('source-contains-prebuilt-flash-project',
+            $item->pointer);
+
+        $self->pointed_hint('source-is-missing', $item->pointer)
+          unless $self->find_source($item, {'.as' => '(?i)\.fla$'});
+    }
+
+    # see #745152
+    # Be robust check also .js
+    if ($item->basename eq 'deployJava.js') {
+        if (
+            lc $item->decoded_utf8
+            =~ m/(?:\A|\v)\s*var\s+deployJava\s*=\s*function/xmsi) {
+
+            $self->pointed_hint('source-is-missing', $item->pointer)
+              unless $self->find_source($item,
+                {'.txt' => '(?i)\.js$', $EMPTY => $EMPTY});
+
+            return;
+        }
+    }
+
+    # do not forget to change also $JS_EXT in file.pm
+    if ($item->name
+        =~ m{(?i)[-._](?:compiled|compressed|lite|min|pack(?:ed)?|prod|umd|yc)\.js$}x
+    ) {
+
+        $self->pointed_hint('source-contains-prebuilt-javascript-object',
+            $item->pointer);
+        my %patterns = map {
+            $_ =>
+'(?i)(?:[-._](?:compiled|compressed|lite|min|pack(?:ed)?|prod|umd|yc))?\.js$'
+        } qw(.js _orig.js .js.orig .src.js -src.js .debug.js -debug.js -nc.js);
+
+        $self->pointed_hint('source-is-missing', $item->pointer)
+          unless $self->find_source($item, \%patterns);
+
+        return;
+    }
+
+    my @lines = split(/\n/, $item->bytes);
+    my %line_length;
+    my %semicolon_count;
+
+    my $position = 1;
+    for my $line (@lines) {
+
+        $line_length{$position} = length $line;
+        $semicolon_count{$position} = ($line =~ tr/;/;/);
+
+    } continue {
+        ++$position;
+    }
+
+    my $longest = max_by { $line_length{$_} } keys %line_length;
+    my $most = max_by { $semicolon_count{$_} } keys %semicolon_count;
+
+    return
+      if !defined $longest || $line_length{$longest} <= $VERY_LONG_LINE_LENGTH;
+
+    if ($item->basename =~ m{\.js$}i) {
+
+        $self->pointed_hint('source-contains-prebuilt-javascript-object',
+            $item->pointer);
+
+        # Check for missing source.  It will check
+        # for the source file in well known directories
+        $self->pointed_hint('source-is-missing', $item->pointer)
+          unless $self->find_source(
+            $item,
+            {
+                '.debug.js' => '(?i)\.js$',
+                '-debug.js' => '(?i)\.js$',
+                $EMPTY => $EMPTY
+            }
+          );
+    }
+
+    if ($item->basename =~ /\.(?:x?html?\d?|xht)$/i) {
+
+        # html file
+        $self->pointed_hint('source-is-missing', $item->pointer)
+          unless $self->find_source($item, {'.fragment.js' => $DOLLAR});
+    }
+
+    return;
+}
+
+sub find_source {
+    my ($self, $item, $patternref) = @_;
+
+    $patternref //= {};
+
+    return undef
+      unless $item->is_regular_file;
+
+    return undef
+      if $self->processable->is_non_free;
+
+    my %patterns = %{$patternref};
+
+    my @alternatives;
+    for my $replacement (keys %patterns) {
+
+        my $newname = $item->basename;
+
+        # empty pattern would repeat the last regex compiled
+        my $pattern = $patterns{$replacement};
+        $newname =~ s/$pattern/$replacement/
+          if length $pattern;
+
+        push(@alternatives, $newname)
+          if length $newname;
+    }
+
+    my $index = $self->processable->patched;
+    my @candidates;
+
+    # add standard locations
+    push(@candidates,
+        $index->resolve_path('debian/missing-sources/' . $item->name));
+    push(@candidates,
+        $index->resolve_path('debian/missing-sources/' . $item->basename));
+
+    my $dirname = $item->dirname;
+    my $parentname = basename($dirname);
+
+    my @absolute = (
+        # libtool
+        '.libs',
+        ".libs/$dirname",
+        # mathjax
+        'unpacked',
+        # for missing source set in debian
+        'debian',
+        'debian/missing-sources',
+        "debian/missing-sources/$dirname"
+    );
+
+    for my $absolute (@absolute) {
+        push(@candidates, $index->resolve_path("$absolute/$_"))
+          for @alternatives;
+    }
+
+    my @relative = (
+        # likely in current dir
+        $DOT,
+        # for binary object built by libtool
+        $DOUBLE_DOT,
+        # maybe in src subdir
+        './src',
+        # maybe in ../src subdir
+        '../src',
+        "../../src/$parentname",
+        # emscripten
+        './flash-src/src/net/gimite/websocket',
+    );
+
+    for my $relative (@relative) {
+        push(@candidates, $item->resolve_path("$relative/$_"))
+          for @alternatives;
+    }
+
+    my @found = grep { defined } @candidates;
+
+    # careful with behavior around empty arrays
+    my $source = first_value { $_->name ne $item->name } @found;
+
+    return $source;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Special.pm b/lib/Lintian/Check/Files/Special.pm
new file mode 100644
index 0000000..7a59006
--- /dev/null
+++ b/lib/Lintian/Check/Files/Special.pm
@@ -0,0 +1,50 @@
+# files/special -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Special;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      if $item->is_file || $item->is_dir || $item->is_symlink;
+
+    $self->pointed_hint('special-file', $item->pointer,
+        sprintf('%04o',$item->operm));
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/SymbolicLinks.pm b/lib/Lintian/Check/Files/SymbolicLinks.pm
new file mode 100644
index 0000000..0edcde2
--- /dev/null
+++ b/lib/Lintian/Check/Files/SymbolicLinks.pm
@@ -0,0 +1,229 @@
+# files/symbolic-links -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::SymbolicLinks;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SLASH => q{/};
+const my $DOT => q{.};
+const my $DOUBLE_DOT => q{..};
+const my $VERTICAL_BAR => q{|};
+const my $ARROW => q{->};
+
+# an OR (|) regex of all compressed extension
+has COMPRESS_FILE_EXTENSIONS_OR_ALL => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $COMPRESS_FILE_EXTENSIONS
+          = $self->data->load('files/compressed-file-extensions',qr/\s+/);
+
+        my $text = join($VERTICAL_BAR,
+            (map { quotemeta } $COMPRESS_FILE_EXTENSIONS->all));
+
+        return qr/$text/;
+    }
+);
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_symlink;
+
+    # absolute links cannot be resolved
+    if ($item->link =~ m{^/}) {
+
+        # allow /dev/null link target for masked systemd service files
+        $self->pointed_hint('absolute-symbolic-link-target-in-source',
+            $item->pointer, $item->link)
+          unless $item->link eq '/dev/null';
+    }
+
+    # some relative links cannot be resolved inside the source
+    $self->pointed_hint('wayward-symbolic-link-target-in-source',
+        $item->pointer, $item->link)
+      unless defined $_->link_normalized || $item->link =~ m{^/};
+
+    return;
+}
+
+sub is_tmp_path {
+    my ($path) = @_;
+
+    return 1
+      if $path =~ m{^tmp/.}
+      || $path =~ m{^(?:var|usr)/tmp/.}
+      || $path =~ m{^/dev/shm/};
+
+    return 0;
+}
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_symlink;
+
+    my $mylink = $item->link;
+    $self->pointed_hint('symlink-has-double-slash', $item->pointer,$item->link)
+      if $mylink =~ s{//+}{/}g;
+
+    $self->pointed_hint('symlink-ends-with-slash', $item->pointer, $item->link)
+      if $mylink =~ s{(.)/$}{$1};
+
+    # determine top-level directory of file
+    $item->name =~ m{^/?([^/]*)};
+    my $filetop = $1;
+
+    if ($mylink =~ m{^/([^/]*)}) {
+        my $flinkname = substr($mylink,1);
+        # absolute link, including link to /
+        # determine top-level directory of link
+        my $linktop = $1;
+
+        if ($self->processable->type ne 'udeb' and $filetop eq $linktop) {
+            # absolute links within one toplevel directory are _not_ ok!
+            $self->pointed_hint('absolute-symlink-in-top-level-folder',
+                $item->pointer, $item->link);
+        }
+
+        my $BUILD_PATH_REGEX
+          = $self->data->load('files/build-path-regex',qr/~~~~~/);
+
+        for my $pattern ($BUILD_PATH_REGEX->all) {
+
+            $self->pointed_hint('symlink-target-in-build-tree',
+                $item->pointer, $mylink)
+              if $flinkname =~ m{$pattern}xms;
+        }
+
+        $self->pointed_hint('symlink-target-in-tmp', $item->pointer,$mylink)
+          if is_tmp_path($flinkname);
+
+        # Any other case is already definitely non-recursive
+        $self->pointed_hint('symlink-is-self-recursive', $item->pointer,
+            $item->link)
+          if $mylink eq $SLASH;
+
+    } else {
+        # relative link, we can assume from here that the link
+        # starts nor ends with /
+
+        my @filecomponents = split(m{/}, $item->name);
+        # chop off the name of the symlink
+        pop @filecomponents;
+
+        my @linkcomponents = split(m{/}, $mylink);
+
+        # handle `../' at beginning of $item->link
+        my ($lastpop, $linkcomponent);
+        while ($linkcomponent = shift @linkcomponents) {
+            if ($linkcomponent eq $DOT) {
+                $self->pointed_hint('symlink-contains-spurious-segments',
+                    $item->pointer, $item->link)
+                  unless $mylink eq $DOT;
+                next;
+            }
+            last if $linkcomponent ne $DOUBLE_DOT;
+            if (@filecomponents) {
+                $lastpop = pop @filecomponents;
+            } else {
+                $self->pointed_hint('symlink-has-too-many-up-segments',
+                    $item->pointer, $item->link);
+                goto NEXT_LINK;
+            }
+        }
+
+        if (!defined $linkcomponent) {
+            # After stripping all starting .. components, nothing left
+            $self->pointed_hint('symlink-is-self-recursive', $item->pointer,
+                $item->link);
+        }
+
+        # does the link go up and then down into the same
+        # directory?  (lastpop indicates there was a backref
+        # at all, no linkcomponent means the symlink doesn't
+        # get up anymore)
+        if (   defined $lastpop
+            && defined $linkcomponent
+            && $linkcomponent eq $lastpop) {
+            $self->pointed_hint('lengthy-symlink', $item->pointer,$item->link);
+        }
+
+        unless (@filecomponents) {
+            # we've reached the root directory
+            if (   ($self->processable->type ne 'udeb')
+                && (!defined $linkcomponent)
+                || ($filetop ne $linkcomponent)) {
+
+                # relative link into other toplevel directory.
+                # this hits a relative symbolic link in the root too.
+                $self->pointed_hint('relative-symlink', $item->pointer,
+                    $item->link);
+            }
+        }
+
+        # check additional segments for mistakes like `foo/../bar/'
+        foreach (@linkcomponents) {
+            if ($_ eq $DOUBLE_DOT || $_ eq $DOT) {
+                $self->pointed_hint('symlink-contains-spurious-segments',
+                    $item->pointer, $item->link);
+                last;
+            }
+        }
+    }
+  NEXT_LINK:
+
+    my $pattern = $self->COMPRESS_FILE_EXTENSIONS_OR_ALL;
+
+    # symlink pointing to a compressed file
+    if ($item->link =~ qr{ [.] ($pattern) \s* $}x) {
+
+        my $extension = $1;
+
+        # symlink has correct extension?
+        $self->pointed_hint('compressed-symlink-with-wrong-ext',
+            $item->pointer, $item->link)
+          unless $item->name =~ qr{[.]$extension\s*$};
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/SymbolicLinks/Broken.pm b/lib/Lintian/Check/Files/SymbolicLinks/Broken.pm
new file mode 100644
index 0000000..39ae2d2
--- /dev/null
+++ b/lib/Lintian/Check/Files/SymbolicLinks/Broken.pm
@@ -0,0 +1,119 @@
+# files/symbolic-links/broken -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2011 Niels Thykier
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::SymbolicLinks::Broken;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use File::Basename qw(dirname);
+use List::SomeUtils qw(any);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $ASTERISK => q{*};
+
+has wildcard_links => (is => 'rw', default => sub{ [] });
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_symlink;
+
+    # target relative to the package root
+    my $path = $item->link_normalized;
+
+    # unresolvable link
+    unless (defined $path) {
+
+        $self->pointed_hint('package-contains-unsafe-symlink', $item->pointer);
+        return;
+    }
+
+    # will always have links to the package root (although
+    # self-recursive and possibly not very useful)
+    return
+      if $path eq $EMPTY;
+
+    # If it contains a "*" it probably a bad
+    # ln -s target/*.so link expansion.  We do not bother looking
+    # for other broken symlinks as people keep adding new special
+    # cases and it is not worth it.
+    push(@{$self->wildcard_links}, $item)
+      if index($item->link, $ASTERISK) >= 0;
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    return
+      unless @{$self->wildcard_links};
+
+    # get prerequisites from same source package
+    my @prerequisites
+      = @{$self->group->direct_dependencies($self->processable)};
+
+    for my $item (@{$self->wildcard_links}){
+
+        # target relative to the package root
+        my $path = $item->link_normalized;
+
+        # destination is in the package
+        next
+          if $self->processable->installed->lookup($path)
+          || $self->processable->installed->lookup("$path/");
+
+        # does the link point to any prerequisites in same source package
+        next
+          if
+          any {$_->installed->lookup($path) || $_->installed->lookup("$path/")}
+          @prerequisites;
+
+        # link target
+        my $target = $item->link;
+
+        # strip leading slashes for reporting
+        $target =~ s{^/+}{};
+
+        # nope - not found in any of our direct dependencies.  Ergo it is
+        # a broken "ln -s target/*.so link" expansion.
+        $self->pointed_hint('package-contains-broken-symlink-wildcard',
+            $item->pointer, $target);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Unicode/Trojan.pm b/lib/Lintian/Check/Files/Unicode/Trojan.pm
new file mode 100644
index 0000000..5c4f2e1
--- /dev/null
+++ b/lib/Lintian/Check/Files/Unicode/Trojan.pm
@@ -0,0 +1,134 @@
+# files/unicode/trojan -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Unicode::Trojan;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(decode_utf8 encode_utf8 valid_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $DOUBLE_QUOTE => q{"};
+
+const my %NAMES_BY_CHARACTER => (
+    qq{\N{ARABIC LETTER MARK}} => 'ARABIC LETTER MARK', # U+061C
+    qq{\N{LEFT-TO-RIGHT MARK}} => 'LEFT-TO-RIGHT MARK', # U+200E
+    qq{\N{RIGHT-TO-LEFT MARK}} => 'RIGHT-TO-LEFT MARK', # U+200F
+    qq{\N{LEFT-TO-RIGHT EMBEDDING}} => 'LEFT-TO-RIGHT EMBEDDING', # U+202A
+    qq{\N{RIGHT-TO-LEFT EMBEDDING}} => 'RIGHT-TO-LEFT EMBEDDING', # U+202B
+    qq{\N{POP DIRECTIONAL FORMATTING}} =>'POP DIRECTIONAL FORMATTING', # U+202C
+    qq{\N{LEFT-TO-RIGHT OVERRIDE}} => 'LEFT-TO-RIGHT OVERRIDE', # U+202D
+    qq{\N{RIGHT-TO-LEFT OVERRIDE}} => 'RIGHT-TO-LEFT OVERRIDE', # U+202E
+    qq{\N{LEFT-TO-RIGHT ISOLATE}} => 'LEFT-TO-RIGHT ISOLATE', # U+2066
+    qq{\N{RIGHT-TO-LEFT ISOLATE}} => 'RIGHT-TO-LEFT ISOLATE', # U+2067
+    qq{\N{FIRST STRONG ISOLATE}} => 'FIRST STRONG ISOLATE', # U+2068
+    qq{\N{POP DIRECTIONAL ISOLATE}} => 'POP DIRECTIONAL ISOLATE', # U+2069
+);
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    $self->check_for_trojan($item);
+
+    return;
+}
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    $self->check_for_trojan($item);
+
+    return;
+}
+
+sub check_for_trojan {
+    my ($self, $item) = @_;
+
+    if (valid_utf8($item->name)) {
+
+        my $decoded_name = decode_utf8($item->name);
+
+        # all file names
+        for my $character (keys %NAMES_BY_CHARACTER) {
+
+            $self->pointed_hint(
+                'unicode-trojan',
+                $item->pointer,
+                'File name',
+                sprintf('U+%vX', $character),
+                $DOUBLE_QUOTE. $NAMES_BY_CHARACTER{$character}. $DOUBLE_QUOTE
+            ) if $decoded_name =~ m{\Q$character\E};
+        }
+    }
+
+    return
+      unless $item->is_script;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        chomp $line;
+
+        next
+          unless valid_utf8($line);
+
+        my $decoded = decode_utf8($line);
+
+        my $pointer = $item->pointer($position);
+
+        for my $character (keys %NAMES_BY_CHARACTER) {
+
+            $self->pointed_hint(
+                'unicode-trojan',
+                $pointer,
+                'Contents',
+                sprintf('U+%vX', $character),
+                $DOUBLE_QUOTE. $NAMES_BY_CHARACTER{$character}. $DOUBLE_QUOTE
+            )if $decoded =~ m{\Q$character\E};
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Unwanted.pm b/lib/Lintian/Check/Files/Unwanted.pm
new file mode 100644
index 0000000..779e4f5
--- /dev/null
+++ b/lib/Lintian/Check/Files/Unwanted.pm
@@ -0,0 +1,55 @@
+# files/unwanted -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Unwanted;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    $self->pointed_hint('backup-file-in-package', $item->pointer)
+      if $item->name =~ /~$/
+      || $item->name =~ m{\#[^/]+\#$}
+      || $item->name =~ m{/\.[^/]+\.swp$};
+
+    $self->pointed_hint('nfs-temporary-file-in-package', $item->pointer)
+      if $item->name =~ m{/\.nfs[^/]+$};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/UsrMerge.pm b/lib/Lintian/Check/Files/UsrMerge.pm
new file mode 100644
index 0000000..be5a06d
--- /dev/null
+++ b/lib/Lintian/Check/Files/UsrMerge.pm
@@ -0,0 +1,53 @@
+# files/usr-merge -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::UsrMerge;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    my $quotedpath = quotemeta($item->name);
+
+    $self->pointed_hint('package-contains-usr-unmerged-pathnames',
+        $item->pointer)
+      if $item->name =~ m{^(?:bin|sbin|lib.*)/.+$}
+      && !$item->is_symlink
+      && !$item->is_dir
+      && $item->link !~ m{^usr/$quotedpath$};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Files/Vcs.pm b/lib/Lintian/Check/Files/Vcs.pm
new file mode 100644
index 0000000..2f5b8f5
--- /dev/null
+++ b/lib/Lintian/Check/Files/Vcs.pm
@@ -0,0 +1,113 @@
+# files/vcs -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Files::Vcs;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $VERTICAL_BAR => q{|};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# an OR (|) regex of all vcs files
+has VCS_PATTERNS_ORED => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my @vcs_patterns;
+
+        my $COMPRESS_FILE_EXTENSIONS
+          = $self->data->load('files/compressed-file-extensions',qr/\s+/);
+
+        my @quoted_extension_patterns
+          = map { quotemeta } $COMPRESS_FILE_EXTENSIONS->all;
+        my $ored_extension_patterns= ored_patterns(@quoted_extension_patterns);
+
+        my $VCS_CONTROL_PATTERNS
+          = $self->data->load('files/vcs-control-files', qr/\s+/);
+
+        for my $pattern ($VCS_CONTROL_PATTERNS->all) {
+            $pattern =~ s/\$[{]COMPRESS_EXT[}]/(?:$ored_extension_patterns)/g;
+            push(@vcs_patterns, $pattern);
+        }
+
+        my $ored_vcs_patterns = ored_patterns(@vcs_patterns);
+
+        return $ored_vcs_patterns;
+    }
+);
+
+sub ored_patterns {
+    my (@patterns) = @_;
+
+    my @protected = map { "(?:$_)" } @patterns;
+
+    my $ored = join($VERTICAL_BAR, @protected);
+
+    return $ored;
+}
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    if ($item->is_file) {
+
+        my $pattern = $self->VCS_PATTERNS_ORED;
+
+        $self->pointed_hint('package-contains-vcs-control-file',$item->pointer)
+          if $item->name =~ m{$pattern}x
+          && $item->name !~ m{^usr/share/cargo/registry/};
+
+        if ($item->name =~ m/svn-commit.*\.tmp$/) {
+            $self->pointed_hint('svn-commit-file-in-package', $item->pointer);
+        }
+
+        if ($item->name =~ m/svk-commit.+\.tmp$/) {
+            $self->pointed_hint('svk-commit-file-in-package', $item->pointer);
+        }
+
+    } elsif ($item->is_dir) {
+
+        $self->pointed_hint('package-contains-vcs-control-dir', $item->pointer)
+          if $item->name =~ m{/CVS/?$}
+          || $item->name =~ m{/\.(?:svn|bzr|git|hg)/?$}
+          || $item->name =~ m{/\.arch-ids/?$}
+          || $item->name =~ m{/\{arch\}/?$};
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fonts.pm b/lib/Lintian/Check/Fonts.pm
new file mode 100644
index 0000000..edb5c5c
--- /dev/null
+++ b/lib/Lintian/Check/Fonts.pm
@@ -0,0 +1,92 @@
+# fonts -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fonts;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SPACE => q{ };
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->basename
+      =~ m{ [\w-]+ [.] (?:[to]tf | pfb | woff2? | eot) (?:[.]gz)? $}ix;
+
+    my $font = $item->basename;
+
+    my $FONT_PACKAGES = $self->data->fonts;
+
+    my @declared_shippers = $FONT_PACKAGES->installed_by($font);
+
+    if (@declared_shippers) {
+
+        # Fonts in xfonts-tipa are really shipped by tipa.
+        my @renamed
+          = map { $_ eq 'xfonts-tipa' ? 'tipa' : $_ } @declared_shippers;
+
+        my $list
+          = $LEFT_PARENTHESIS
+          . join($SPACE, (sort @renamed))
+          . $RIGHT_PARENTHESIS;
+
+        $self->pointed_hint('duplicate-font-file', $item->pointer, 'also in',
+            $list)
+          unless (any { $_ eq $self->processable->name } @renamed)
+          || $self->processable->type eq 'udeb';
+
+    } else {
+        unless ($item->name =~ m{^usr/lib/R/site-library/}) {
+
+            $self->pointed_hint('font-in-non-font-package', $item->pointer)
+              unless $self->processable->name =~ m/^(?:[ot]tf|t1|x?fonts)-/;
+
+            $self->pointed_hint('font-outside-font-dir', $item->pointer)
+              unless $item->name =~ m{^usr/share/fonts/};
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fonts/Opentype.pm b/lib/Lintian/Check/Fonts/Opentype.pm
new file mode 100644
index 0000000..9ea5dac
--- /dev/null
+++ b/lib/Lintian/Check/Fonts/Opentype.pm
@@ -0,0 +1,95 @@
+# fonts/opentype -- lintian check script -*- perl -*-
+
+# Copyright (C) 2019 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fonts::Opentype;
+
+use v5.20;
+use warnings;
+use utf8;
+use autodie qw(open);
+
+use Const::Fast;
+use Font::TTF::Font;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SPACE => q{ };
+const my $COMMA => q{,};
+
+const my $PERMISSIONS_MASK => 0x0f;
+const my $NEVER_EMBED_FLAG => 0x02;
+const my $PRINT_PREVIEW_ONLY_FLAG => 0x04;
+const my $EDIT_ONLY_FLAG => 0x08;
+
+sub visit_installed_files {
+    my ($self, $file) = @_;
+
+    return
+      unless $file->is_file;
+
+    return
+      unless $file->file_type =~ /^OpenType font data/;
+
+    $self->pointed_hint('opentype-font-wrong-filename', $file->pointer)
+      unless $file->name =~ /\.otf$/i;
+
+    my $font = Font::TTF::Font->open($file->unpacked_path);
+
+    my $os2 = defined $font ? $font->{'OS/2'} : undef;
+    my $table = defined $os2 ? $os2->read : undef;
+    my $fs_type = defined $table ? $table->{fsType} : undef;
+
+    $font->release
+      if defined $font;
+
+    return
+      unless defined $fs_type;
+
+    my @clauses;
+
+    my $permissions = $fs_type & $PERMISSIONS_MASK;
+    push(@clauses, 'never embed')
+      if $permissions & $NEVER_EMBED_FLAG;
+    push(@clauses, 'preview/print only')
+      if $permissions & $PRINT_PREVIEW_ONLY_FLAG;
+    push(@clauses, 'edit only')
+      if $permissions & $EDIT_ONLY_FLAG;
+
+    my $terms;
+    $terms = join($COMMA . $SPACE, @clauses)
+      if @clauses;
+
+    $self->pointed_hint('opentype-font-prohibits-installable-embedding',
+        $file->pointer, "($terms)")
+      if length $terms;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fonts/Postscript/Type1.pm b/lib/Lintian/Check/Fonts/Postscript/Type1.pm
new file mode 100644
index 0000000..280eb8f
--- /dev/null
+++ b/lib/Lintian/Check/Fonts/Postscript/Type1.pm
@@ -0,0 +1,130 @@
+# fonts/postscript/type1 -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fonts::Postscript::Type1;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Encode qw(decode);
+use Syntax::Keyword::Try;
+
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Moo;
+use namespace::clean;
+
+const my $SPACE => q{ };
+const my $COLON => q{:};
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ m/PostScript Type 1 font program data/;
+
+    my @command = ('t1disasm', $item->unpacked_path);
+    my $bytes = safe_qx(@command);
+
+    my $output;
+    try {
+        # iso-8859-1 works too, but the Font 1 standard could be older
+        $output = decode('cp1252', $bytes, Encode::FB_CROAK);
+
+    } catch {
+        die 'In file ' . $item->name . $COLON . $SPACE . $@;
+    }
+
+    my @lines = split(/\n/, $output);
+
+    my $foundadobeline = 0;
+
+    for my $line (@lines) {
+
+        if ($foundadobeline) {
+            if (
+                $line =~ m{\A [%\s]*
+                                   All\s*Rights\s*Reserved\.?\s*
+                                       \Z}xsmi
+            ) {
+                $self->pointed_hint(
+                    'license-problem-font-adobe-copyrighted-fragment',
+                    $item->pointer);
+
+                last;
+            }
+        }
+
+        $foundadobeline = 1
+          if $line =~ m{\A
+                               [%\s]*Copyright\s*\(c\) \s*
+                               19\d{2}[\-\s]19\d{2}\s*
+                               Adobe\s*Systems\s*Incorporated\.?\s*\Z}xsmi;
+
+# If copy pasted from black book they are
+# copyright adobe a few line before the only
+# place where the startlock is documented is
+# in the black book copyrighted fragment
+#
+# 2023-06-05: this check has been adjusted because
+# Adobe's type hint code[1] (including Flex[2]) became
+# open source[3] with an Apache-2.0 license[4] as
+# committed on 2014-09-19, making that check a false
+# positive[7].
+#
+# We continue to check for copyrighted code that is not
+# available under an open source license from the origin
+# publication,  "Adobe Type 1 Font Format"[5][6].
+#
+# [1] - https://github.com/adobe-type-tools/afdko/blob/2bf85cf44a64148353b24db17e0cc41ede5493b1/FDK/Tools/Programs/public/lib/source/t1write/t1write_hintothers.h
+# [2] - https://github.com/adobe-type-tools/afdko/blob/2bf85cf44a64148353b24db17e0cc41ede5493b1/FDK/Tools/Programs/public/lib/source/t1write/t1write_flexothers.h
+# [3] - https://www.mail-archive.com/debian-bugs-dist@lists.debian.org/msg1375813.html
+# [4] - https://github.com/adobe-type-tools/afdko/blob/2bf85cf44a64148353b24db17e0cc41ede5493b1/LICENSE.txt
+# [5] - https://adobe-type-tools.github.io/font-tech-notes/pdfs/T1_SPEC.pdf
+# [6] - https://lccn.loc.gov/90042516
+# [7] - https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1029555
+        if ($line =~ m/UniqueID\s*6859/) {
+
+            $self->pointed_hint(
+                'license-problem-font-adobe-copyrighted-fragment-no-credit',
+                $item->pointer);
+
+            last;
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Fonts/Truetype.pm b/lib/Lintian/Check/Fonts/Truetype.pm
new file mode 100644
index 0000000..71e120a
--- /dev/null
+++ b/lib/Lintian/Check/Fonts/Truetype.pm
@@ -0,0 +1,95 @@
+# fonts/truetype -- lintian check script -*- perl -*-
+
+# Copyright (C) 2019 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Fonts::Truetype;
+
+use v5.20;
+use warnings;
+use utf8;
+use autodie qw(open);
+
+use Const::Fast;
+use Font::TTF::Font;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SPACE => q{ };
+const my $COMMA => q{,};
+
+const my $PERMISSIONS_MASK => 0x0f;
+const my $NEVER_EMBED_FLAG => 0x02;
+const my $PRINT_PREVIEW_ONLY_FLAG => 0x04;
+const my $EDIT_ONLY_FLAG => 0x08;
+
+sub visit_installed_files {
+    my ($self, $file) = @_;
+
+    return
+      unless $file->is_file;
+
+    return
+      unless $file->file_type =~ /^TrueType Font data/;
+
+    $self->pointed_hint('truetype-font-wrong-filename', $file->pointer)
+      unless $file->name =~ /\.ttf$/i;
+
+    my $font = Font::TTF::Font->open($file->unpacked_path);
+
+    my $os2 = defined $font ? $font->{'OS/2'} : undef;
+    my $table = defined $os2 ? $os2->read : undef;
+    my $fs_type = defined $table ? $table->{fsType} : undef;
+
+    $font->release
+      if defined $font;
+
+    return
+      unless defined $fs_type;
+
+    my @clauses;
+
+    my $permissions = $fs_type & $PERMISSIONS_MASK;
+    push(@clauses, 'never embed')
+      if $permissions & $NEVER_EMBED_FLAG;
+    push(@clauses, 'preview/print only')
+      if $permissions & $PRINT_PREVIEW_ONLY_FLAG;
+    push(@clauses, 'edit only')
+      if $permissions & $EDIT_ONLY_FLAG;
+
+    my $terms;
+    $terms = join($COMMA . $SPACE, @clauses)
+      if @clauses;
+
+    $self->pointed_hint('truetype-font-prohibits-installable-embedding',
+        $file->pointer, "($terms)")
+      if length $terms;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/ForeignOperatingSystems.pm b/lib/Lintian/Check/ForeignOperatingSystems.pm
new file mode 100644
index 0000000..7f9fd7d
--- /dev/null
+++ b/lib/Lintian/Check/ForeignOperatingSystems.pm
@@ -0,0 +1,63 @@
+# foreign-operating-systems -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::ForeignOperatingSystems;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # Windows development files
+    $self->pointed_hint('windows-devel-file-in-package', $item->pointer)
+      if $item->name =~ m{/.+\.(?:vcproj|sln|ds[pw])(?:\.gz)?$}
+      && $item->name !~ m{^usr/share/doc/};
+
+    # autogenerated databases from other OSes
+    $self->pointed_hint('windows-thumbnail-database-in-package',$item->pointer)
+      if $item->name =~ m{/Thumbs\.db(?:\.gz)?$}i;
+
+    $self->pointed_hint('macos-ds-store-file-in-package', $item->pointer)
+      if $item->name =~ m{/\.DS_Store(?:\.gz)?$};
+
+    $self->pointed_hint('macos-resource-fork-file-in-package', $item->pointer)
+      if $item->name =~ m{/\._[^_/][^/]*$}
+      && $item->name !~ m/\.swp$/;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Games.pm b/lib/Lintian/Check/Games.pm
new file mode 100644
index 0000000..f9ca58a
--- /dev/null
+++ b/lib/Lintian/Check/Games.pm
@@ -0,0 +1,90 @@
+# games -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Games;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # non-games-specific data in games subdirectory
+    if ($item->name=~ m{^usr/share/games/(?:applications|mime|icons|pixmaps)/}
+        && !$item->is_dir) {
+
+        $self->pointed_hint('global-data-in-games-directory', $item->pointer);
+    }
+
+    return;
+}
+
+sub dir_counts {
+    my ($self, $filename) = @_;
+
+    my $item = $self->processable->installed->lookup($filename);
+
+    return 0
+      unless $item;
+
+    return scalar $item->children;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $section = $self->processable->fields->value('Section');
+
+    # section games but nothing in /usr/games
+    # any binary counts to avoid game-data false positives:
+    my $games = $self->dir_counts('usr/games/');
+    my $other = $self->dir_counts('bin/') + $self->dir_counts('usr/bin/');
+
+    if ($other) {
+        if ($section =~ m{games$}) {
+
+            if ($games) {
+                $self->hint('package-section-games-but-has-usr-bin');
+
+            } else {
+                $self->hint('package-section-games-but-contains-no-game');
+            }
+        }
+
+    } elsif ($games > 0 and $section !~ m{games$}) {
+        $self->hint('game-outside-section');
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/GroupChecks.pm b/lib/Lintian/Check/GroupChecks.pm
new file mode 100644
index 0000000..79150a1
--- /dev/null
+++ b/lib/Lintian/Check/GroupChecks.pm
@@ -0,0 +1,282 @@
+# group-checks -- lintian check script -*- perl -*-
+
+# Copyright (C) 2011 Niels Thykier <niels@thykier.net>
+# Copyright (C) 2018 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::GroupChecks;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(any);
+
+use Lintian::Relation;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $group = $self->group;
+
+    ## To find circular dependencies, we will first generate Strongly
+    ## Connected Components using Tarjan's algorithm
+    ##
+    ## We are not using DepMap, because it cannot tell how the circles
+    ## are made - only that there exists at least 1 circle.
+
+    # The packages a.k.a. nodes
+    my (@nodes, %edges, $sccs);
+    my @installables = grep { $_->type ne 'udeb' } $group->get_installables;
+
+    $self->check_file_overlap(@installables);
+
+    for my $installable (@installables) {
+
+        my $deps = $group->direct_dependencies($installable);
+        if (scalar @{$deps} > 0) {
+            # it depends on another package - it can cause
+            # a circular dependency
+            my $pname = $installable->name;
+            push @nodes, $pname;
+            $edges{$pname} = [map { $_->name } @{$deps}];
+            $self->check_multiarch($installable, $deps);
+        }
+    }
+
+    # Bail now if we do not have at least two packages depending
+    # on some other package from this source.
+    return if scalar @nodes < 2;
+
+    $sccs= Lintian::Check::GroupChecks::Graph->new(\@nodes, \%edges)->tarjans;
+
+    for my $comp (@{$sccs}) {
+        # It takes two to tango... erh. make a circular dependency.
+        next if scalar @{$comp} < 2;
+
+        $self->hint('intra-source-package-circular-dependency',
+            (sort @{$comp}));
+    }
+
+    return;
+}
+
+sub check_file_overlap {
+    my ($self, @processables) = @_;
+
+    # make a local copy to be modified
+    my @remaining = @processables;
+
+    # avoids checking the same combo twice
+    while (@remaining > 1) {
+
+        # avoids checking the same combo twice
+        my $one = shift @remaining;
+
+        my @provides_one = $one->fields->trimmed_list('Provides', qr{,});
+        my $relation_one = Lintian::Relation->new->load(
+            join(' | ', $one->name, @provides_one));
+
+        for my $two (@remaining) {
+
+            # poor man's work-around for "Multi-arch: same"
+            next
+              if $one->name eq $two->name;
+
+            my @provides_two = $two->fields->trimmed_list('Provides', qr{,});
+            my $relation_two = Lintian::Relation->new->load(
+                join(' | ', $two->name, @provides_two));
+
+            # $two conflicts/replaces with $one
+            next
+              if $two->relation('Conflicts')->satisfies($relation_one);
+            next
+              if $two->relation('Replaces')->satisfies($one->name);
+
+            # $one conflicts/replaces with $two
+            next
+              if $one->relation('Conflicts')->satisfies($relation_two);
+            next
+              if $one->relation('Replaces')->satisfies($two->name);
+
+            for my $one_file (@{$one->installed->sorted_list}) {
+
+                my $name = $one_file->name;
+
+                $name =~ s{/$}{};
+                my $two_file = $two->installed->lookup($name)
+                  // $two->installed->lookup("$name/");
+                next
+                  unless defined $two_file;
+
+                next
+                  if $one_file->is_dir && $two_file->is_dir;
+
+                $self->hint('binaries-have-file-conflict',
+                    sort($one->name, $two->name), $name);
+            }
+        }
+    }
+
+    return;
+}
+
+sub check_multiarch {
+    my ($self, $processable, $deps) = @_;
+
+    my $KNOWN_DBG_PACKAGE= $self->data->load('common/dbg-pkg',qr/\s*\~\~\s*/);
+
+    my $ma = $processable->fields->value('Multi-Arch') || 'no';
+    if ($ma eq 'same') {
+        for my $dep (@{$deps}) {
+            my $dma = $dep->fields->value('Multi-Arch') || 'no';
+            if ($dma eq 'same' or $dma eq 'foreign') {
+                1; # OK
+            } else {
+                $self->hint(
+                    'dependency-is-not-multi-archified',
+                    join(q{ },
+                        $processable->name, 'depends on',
+                        $dep->name, "(multi-arch: $dma)")
+                );
+            }
+        }
+    } elsif ($ma ne 'same'
+        and ($processable->fields->value('Section') || 'none')
+        =~ m{(?:^|/)debug$}) {
+        # Debug package that isn't M-A: same, exploit that (non-debug)
+        # dependencies is (almost certainly) a package for which the
+        # debug carries debug symbols.
+        for my $dep (@{$deps}) {
+            my $dma = $dep->fields->value('Multi-Arch') || 'no';
+            if ($dma eq 'same'
+                && ($dep->fields->value('Section') || 'none')
+                !~ m{(?:^|/)debug$}){
+
+                # Debug package isn't M-A: same, but depends on a
+                # package that is from same source that isn't a debug
+                # package and that is M-A same.  Thus it is not
+                # possible to install debug symbols for all
+                # (architecture) variants of the binaries.
+                $self->hint(
+                    'debug-package-for-multi-arch-same-pkg-not-coinstallable',
+                    $processable->name . ' => ' . $dep->name
+                  )
+                  unless any { $processable->name =~ m/$_/xms }
+                  $KNOWN_DBG_PACKAGE->all;
+            }
+        }
+    }
+    return;
+}
+
+## Encapsulate Tarjan's algorithm in a class/object to keep
+## the run sub somewhat sane.  Allow this "extra" package as
+## it is not a proper subclass.
+#<<< no Perl tidy (it breaks the no critic comment)
+package Lintian::Check::GroupChecks::Graph;  ## no critic (Modules::ProhibitMultiplePackages)
+#>>>
+
+use Const::Fast;
+
+const my $EMPTY => q{};
+
+sub new {
+    my ($type, $nodes, $edges) = @_;
+    my $self = { nodes => $nodes, edges => $edges};
+    bless $self, $type;
+    return $self;
+}
+
+sub tarjans {
+    my ($self) = @_;
+    my $nodes = $self->{nodes};
+    $self->{index} = 0;
+    $self->{scc} = [];
+    $self->{stack} = [];
+    $self->{on_stack} = {};
+    # The information for each node:
+    #  $self->{node_info}{$node}[X], where X is:
+    #    0 => index
+    #    1 => low_index
+    $self->{node_info} = {};
+    for my $node (@{$nodes}) {
+        $self->_tarjans_sc($node)
+          unless defined $self->{node_info}{$node};
+    }
+    return $self->{scc};
+}
+
+sub _tarjans_sc {
+    my ($self, $node) = @_;
+    my $index = $self->{index};
+    my $stack = $self->{stack};
+    my $ninfo = [$index, $index];
+    my $on_stack = $self->{on_stack};
+    $self->{node_info}{$node} = $ninfo;
+    $index++;
+    $self->{index} = $index;
+    push(@{$stack}, $node);
+    $on_stack->{$node} = 1;
+
+    foreach my $neighbour (@{ $self->{edges}{$node} }){
+        my $nb_info;
+        $nb_info = $self->{node_info}{$neighbour};
+        if (!defined $nb_info){
+            # First time visit
+            $self->_tarjans_sc($neighbour);
+            # refresh $nb_info
+            $nb_info = $self->{node_info}{$neighbour};
+            # min($node.low_index, $neigh.low_index)
+            $ninfo->[1] = $nb_info->[1] if $nb_info->[1] < $ninfo->[1];
+        } elsif (exists $on_stack->{$neighbour})  {
+            # Node is in this component
+            # min($node.low_index, $neigh.index)
+            $ninfo->[1] = $nb_info->[0] if $nb_info->[0] < $ninfo->[1];
+        }
+    }
+    if ($ninfo->[0] == $ninfo->[1]){
+        # the "root" node - create the SSC.
+        my $component = [];
+        my $scc = $self->{scc};
+        my $elem = $EMPTY;
+
+        do {
+            $elem = pop @{$stack};
+            delete $on_stack->{$elem};
+            push(@{$component}, $elem);
+
+        } until $node eq $elem;
+
+        push(@{$scc}, $component);
+    }
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/HugeUsrShare.pm b/lib/Lintian/Check/HugeUsrShare.pm
new file mode 100644
index 0000000..0043586
--- /dev/null
+++ b/lib/Lintian/Check/HugeUsrShare.pm
@@ -0,0 +1,98 @@
+# huge-usr-share -- lintian check script -*- perl -*-
+
+# Copyright (C) 2004 Jeroen van Wolffelaar <jeroen@wolffelaar.nl>
+# Copyright (C) 2018 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::HugeUsrShare;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# Threshold in kB of /usr/share to trigger this warning.  Consider that the
+# changelog alone can be quite big, and cannot be moved away.
+const my $KIB_SIZE_FACTOR => 1024;
+const my $THRESHOLD_SIZE_SOFT => 4096;
+const my $THRESHOLD_SIZE_HARD => 8192;
+const my $PERCENT => 100;
+const my $THRESHOLD_PERCENTAGE => 50;
+
+has total_size => (is => 'rw', default => 0);
+has usrshare_size => (is => 'rw', default => 0);
+
+sub visit_installed_files {
+    my ($self, $file) = @_;
+
+    return
+      unless $file->is_regular_file;
+
+    # space taken up by package
+    $self->total_size($self->total_size + $file->size);
+
+    # space taken up in /usr/share.
+    $self->usrshare_size($self->usrshare_size + $file->size)
+      if $file =~ m{^usr/share/};
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    # skip architecture-dependent packages.
+    my $arch = $self->processable->fields->value('Architecture');
+    return
+      if $arch eq 'all';
+
+    # meaningless; prevents division by zero
+    return
+      if $self->total_size == 0;
+
+    # convert the totals to kilobytes.
+    my $size = sprintf('%.0f', $self->total_size / $KIB_SIZE_FACTOR);
+    my $size_usrshare
+      = sprintf('%.0f', $self->usrshare_size / $KIB_SIZE_FACTOR);
+    my $percentage
+      = sprintf('%.0f', ($self->usrshare_size / $self->total_size) * $PERCENT);
+
+    $self->hint(
+        'arch-dep-package-has-big-usr-share',
+        "${size_usrshare}kB $percentage%"
+      )
+      if ( $percentage > $THRESHOLD_PERCENTAGE
+        && $size_usrshare > $THRESHOLD_SIZE_SOFT)
+      || $size_usrshare > $THRESHOLD_SIZE_HARD;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Images.pm b/lib/Lintian/Check/Images.pm
new file mode 100644
index 0000000..47021d1
--- /dev/null
+++ b/lib/Lintian/Check/Images.pm
@@ -0,0 +1,49 @@
+# images -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Images;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    $self->pointed_hint('image-file-in-usr-lib', $item->pointer)
+      if $item->name =~ m{^usr/lib/}
+      && $item->name =~ m{\.(?:bmp|gif|jpe?g|png|tiff|x[pb]m)$}
+      && !length $item->link;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Images/Filenames.pm b/lib/Lintian/Check/Images/Filenames.pm
new file mode 100644
index 0000000..d728cc6
--- /dev/null
+++ b/lib/Lintian/Check/Images/Filenames.pm
@@ -0,0 +1,126 @@
+# images/filenames -- lintian check script -*- perl -*-
+
+# Copyright (C) 2019 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Images::Filenames;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+my @image_formats = (
+    {
+        name => 'PNG',
+        file_type => qr/^PNG image data/,
+        good_name => sub { $_[0] =~ /\.(?:png|PNG)$/ }
+    },
+    {
+        name => 'JPEG',
+        file_type => qr/^JPEG image data/,
+        good_name => sub { $_[0] =~ /\.(?:jpe?g|JPE?G)$/ }
+    },
+    {
+        name => 'GIF',
+        file_type => qr/^GIF image data/,
+        good_name => sub { $_[0] =~ /\.(?:gif|GIF)$/ }
+    },
+    {
+        name => 'TIFF',
+        file_type => qr/^TIFF image data/,
+        good_name => sub { $_[0] =~ /\.(?:tiff?|TIFF?)$/ }
+    },
+    {
+        name => 'XPM',
+        file_type => qr/^X pixmap image/,
+        good_name => sub { $_[0] =~ /\.(?:xpm|XPM)$/ }
+    },
+    {
+        name => 'Netpbm',
+        file_type => qr/^Netpbm image data/,
+        good_name => sub { $_[0] =~ /\.(?:p[bgpn]m|P[BGPN]M)$/ }
+    },
+    {
+        name => 'SVG',
+        file_type => qr/^SVG Scalable Vector Graphics image/,
+        good_name => sub { $_[0] =~ /\.(?:svg|SVG)$/ }
+    },
+);
+
+# ICO format developed into a container and may contain PNG
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    my $our_format;
+
+    for my $format (@image_formats) {
+
+        if ($item->file_type =~ $format->{file_type}) {
+            $our_format = $format;
+            last;
+        }
+    }
+
+    # not an image
+    return
+      unless $our_format;
+
+    return
+      if $our_format->{good_name}->($item->name);
+
+    my $conflicting_format;
+
+    my @other_formats = grep { $_ != $our_format } @image_formats;
+    for my $format (@other_formats) {
+
+        if ($format->{good_name}->($item->name)) {
+            $conflicting_format = $format;
+            last;
+        }
+    }
+
+    if ($conflicting_format) {
+
+        $self->pointed_hint('image-file-has-conflicting-name',
+            $item->pointer, '(is ' . $our_format->{name} . ')')
+          unless $our_format->{good_name}->($item->name);
+
+    } else {
+        $self->pointed_hint('image-file-has-unexpected-name',
+            $item->pointer, '(is ' . $our_format->{name} . ')');
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Images/Thumbnails.pm b/lib/Lintian/Check/Images/Thumbnails.pm
new file mode 100644
index 0000000..c8cc430
--- /dev/null
+++ b/lib/Lintian/Check/Images/Thumbnails.pm
@@ -0,0 +1,56 @@
+# images/thumbnails -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Images::Thumbnails;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    if (   $item->is_dir
+        && $item->name =~ m{/\.xvpics/?$}) {
+
+        $self->pointed_hint('package-contains-xvpics-dir', $item->pointer);
+    }
+
+    if (   $item->is_dir
+        && $item->name =~ m{/\.thumbnails/?$}) {
+
+        $self->pointed_hint('package-contains-thumbnails-dir', $item->pointer);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Includes/ConfigH.pm b/lib/Lintian/Check/Includes/ConfigH.pm
new file mode 100644
index 0000000..b854a31
--- /dev/null
+++ b/lib/Lintian/Check/Includes/ConfigH.pm
@@ -0,0 +1,56 @@
+# includes/config-h -- lintian check script -*- perl -*-
+
+# Copyright (C) 2019 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Includes::ConfigH;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->name =~ m{^ usr/include/ }x;
+
+    return
+      unless $item->name =~ m{ /config.h $}x;
+
+    $self->hint('package-name-defined-in-config-h', $item->name)
+      if $item->bytes =~ m{ \b PACKAGE_NAME \b }x;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/InitD.pm b/lib/Lintian/Check/InitD.pm
new file mode 100644
index 0000000..304c186
--- /dev/null
+++ b/lib/Lintian/Check/InitD.pm
@@ -0,0 +1,733 @@
+# init.d -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2016-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::InitD;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use File::Basename qw(dirname);
+use List::Compare;
+use List::SomeUtils qw(any none);
+use Unicode::UTF8 qw(encode_utf8);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $DOLLAR => q{$};
+
+const my $RUN_LEVEL_6 => 6;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# A list of valid LSB keywords.  The value is 0 if optional and 1 if required.
+my %LSB_KEYWORDS = (
+    provides            => 1,
+    'required-start'    => 1,
+    'required-stop'     => 1,
+    'should-start'      => 0,
+    'should-stop'       => 0,
+    'default-start'     => 1,
+    'default-stop'      => 1,
+    # These two are actually optional, but we mark
+    # them as required and give them a weaker tag if
+    # they are missing.
+    'short-description' => 1,
+    'description'       => 1
+);
+
+# These init script names should probably not be used in dependencies.
+# Instead, the corresponding virtual facility should be used.
+#
+# checkroot is not included here since cryptsetup needs the root file system
+# mounted but not any other local file systems and therefore correctly depends
+# on checkroot.  There may be other similar situations.
+my %implied_dependencies = (
+    'mountall'   => $DOLLAR . 'local_fs',
+    'mountnfs'   => $DOLLAR . 'remote_fs',
+
+    'hwclock'    => $DOLLAR . 'time',
+    'portmap'    => $DOLLAR . 'portmap',
+    'named'      => $DOLLAR . 'named',
+    'bind9'      => $DOLLAR . 'named',
+    'networking' => $DOLLAR . 'network',
+    'syslog'     => $DOLLAR . 'syslog',
+    'rsyslog'    => $DOLLAR . 'syslog',
+    'sysklogd'   => $DOLLAR . 'syslog'
+);
+
+# Regex to match names of init.d scripts; it is a bit more lax than
+# package names (e.g. allows "_").  We do not allow it to start with a
+# "dash" to avoid confusing it with a command-line option (also,
+# update-rc.d does not allow this).
+our $INITD_NAME_REGEX = qr/[\w\.\+][\w\-\.\+]*/;
+
+my $OPTS_R = qr/-\S+\s*/;
+my $ACTION_R = qr/\w+/;
+my $EXCLUDE_R = qr/if\s+\[\s+-x\s+\S*update-rc\.d/;
+
+sub installable {
+    my ($self) = @_;
+
+    my $pkg = $self->processable->name;
+    my $processable = $self->processable;
+
+    my $initd_dir = $processable->installed->resolve_path('etc/init.d/');
+    my $postinst = $processable->control->lookup('postinst');
+    my $preinst = $processable->control->lookup('preinst');
+    my $postrm = $processable->control->lookup('postrm');
+    my $prerm = $processable->control->lookup('prerm');
+
+    my (%initd_postinst, %initd_postrm);
+
+    # These will never be regular initscripts. (see #918459, #933383
+    # and #941140 etc.)
+    return
+      if $pkg eq 'initscripts'
+      || $pkg eq 'sysvinit';
+
+    # read postinst control file
+    if ($postinst and $postinst->is_file and $postinst->is_open_ok) {
+
+        open(my $fd, '<', $postinst->unpacked_path)
+          or die encode_utf8('Cannot open ' . $postinst->unpacked_path);
+
+        my $position = 1;
+        while (my $line = <$fd>) {
+
+            next
+              if $line =~ /$EXCLUDE_R/;
+
+            $line =~ s/\#.*$//;
+
+            next
+              unless $line =~ m{^(?:.+;|^\s*system[\s\(\']+)?\s*update-rc\.d\s+
+            (?:$OPTS_R)*($INITD_NAME_REGEX)\s+($ACTION_R)}x;
+
+            my ($name,$opt) = ($1,$2);
+            next
+              if $opt eq 'remove';
+
+            my $pointer = $postinst->pointer($position);
+
+            if ($initd_postinst{$name}++ == 1) {
+
+                $self->pointed_hint('duplicate-updaterc.d-calls-in-postinst',
+                    $pointer, $name);
+                next;
+            }
+
+            $self->pointed_hint(
+                'output-of-updaterc.d-not-redirected-to-dev-null',
+                $pointer, $name)
+              unless $line =~ m{>\s*/dev/null};
+
+        } continue {
+            ++$position;
+        }
+
+        close $fd;
+    }
+
+    # read preinst control file
+    if ($preinst and $preinst->is_file and $preinst->is_open_ok) {
+
+        open(my $fd, '<', $preinst->unpacked_path)
+          or die encode_utf8('Cannot open ' . $preinst->unpacked_path);
+
+        my $position = 1;
+        while (my $line = <$fd>) {
+
+            next
+              if $line =~ /$EXCLUDE_R/;
+
+            $line =~ s/\#.*$//;
+            next
+              unless $line =~ m{update-rc\.d \s+
+                       (?:$OPTS_R)*($INITD_NAME_REGEX) \s+
+                       ($ACTION_R)}x;
+
+            my $name = $1;
+            my $option = $2;
+            next
+              if $option eq 'remove';
+
+            my $pointer = $preinst->pointer($position);
+
+            $self->pointed_hint('preinst-calls-updaterc.d',
+                $pointer, $name, $option);
+
+        } continue {
+            ++$position;
+        }
+
+        close $fd;
+    }
+
+    # read postrm control file
+    if ($postrm and $postrm->is_file and $postrm->is_open_ok) {
+
+        open(my $fd, '<', $postrm->unpacked_path)
+          or die encode_utf8('Cannot open ' . $postrm->unpacked_path);
+
+        my $position = 1;
+        while (my $line = <$fd>) {
+
+            next
+              if $line =~ /$EXCLUDE_R/;
+
+            $line =~ s/\#.*$//;
+
+            next
+              unless $line =~ /update-rc\.d\s+(?:$OPTS_R)*($INITD_NAME_REGEX)/;
+
+            my $name = $1;
+
+            my $pointer = $postrm->pointer($position);
+
+            if ($initd_postrm{$name}++ == 1) {
+
+                $self->pointed_hint('duplicate-updaterc.d-calls-in-postrm',
+                    $pointer, $name);
+                next;
+            }
+
+            $self->pointed_hint(
+                'output-of-updaterc.d-not-redirected-to-dev-null',
+                $pointer, $name)
+              unless $line =~ m{>\s*/dev/null};
+
+        } continue {
+            ++$position;
+        }
+
+        close $fd;
+    }
+
+    # read prerm control file
+    if ($prerm and $prerm->is_file and $prerm->is_open_ok) {
+
+        open(my $fd, '<', $prerm->unpacked_path)
+          or die encode_utf8('Cannot open ' . $prerm->unpacked_path);
+
+        my $position = 1;
+        while (my $line = <$fd>) {
+
+            next
+              if $line =~ /$EXCLUDE_R/;
+
+            $line =~ s/\#.*$//;
+
+            next
+              unless $line =~ /update-rc\.d\s+(?:$OPTS_R)*($INITD_NAME_REGEX)/;
+
+            my $name = $1;
+
+            my $pointer = $prerm->pointer($position);
+
+            $self->pointed_hint('prerm-calls-updaterc.d', $pointer, $name);
+
+        } continue {
+            ++$position;
+        }
+
+        close $fd;
+    }
+
+    # init.d scripts have to be removed in postrm
+    for (keys %initd_postinst) {
+        if ($initd_postrm{$_}) {
+            delete $initd_postrm{$_};
+        } else {
+
+            $self->pointed_hint(
+                'postrm-does-not-call-updaterc.d-for-init.d-script',
+                $postrm->pointer, "etc/init.d/$_");
+        }
+    }
+
+    for (keys %initd_postrm) {
+        $self->pointed_hint('postrm-contains-additional-updaterc.d-calls',
+            $postrm->pointer, "etc/init.d/$_");
+    }
+
+    for my $initd_file (keys %initd_postinst) {
+
+        my $item;
+        $item = $initd_dir->child($initd_file)
+          if $initd_dir;
+
+        unless (
+            (defined $item && $item->resolve_path)
+            ||(    defined $item
+                && $item->is_symlink
+                && $item->link eq '/lib/init/upstart-job')
+        ) {
+
+            $self->hint('init.d-script-not-included-in-package',
+                "etc/init.d/$initd_file");
+
+            next;
+        }
+
+        # init.d scripts have to be marked as conffiles unless they're
+        # symlinks.
+        $self->hint('init.d-script-not-marked-as-conffile',
+            "etc/init.d/$initd_file")
+          if !defined $item
+          || ( !$processable->declared_conffiles->is_known($item->name)
+            && !$item->is_symlink);
+
+        # Check if file exists in package and check the script for
+        # other issues if it was included in the package.
+        $self->check_init($item);
+    }
+    $self->check_defaults;
+
+    return
+      unless defined $initd_dir && $initd_dir->is_dir;
+
+    # files actually installed in /etc/init.d should match our list :-)
+    for my $script ($initd_dir->children) {
+
+        next
+          if !$script->is_dir
+          && (any {$script->basename eq $_}qw(README skeleton rc rcS));
+
+        my $tag_name = 'script-in-etc-init.d-not-registered-via-update-rc.d';
+
+        # In an upstart system, such as Ubuntu, init scripts are symlinks to
+        # upstart-job which are not registered with update-rc.d.
+        $tag_name= 'upstart-job-in-etc-init.d-not-registered-via-update-rc.d'
+          if $script->is_symlink
+          && $script->link eq '/lib/init/upstart-job';
+
+        # If $initd_postinst is true for this script, we already
+        # checked the syntax in the above loop.  Check the syntax of
+        # unregistered scripts so that we get more complete Lintian
+        # coverage in the first pass.
+        unless ($initd_postinst{$script->basename}) {
+
+            $self->pointed_hint($tag_name, $script->pointer);
+            $self->check_init($script);
+        }
+    }
+
+    return;
+}
+
+sub check_init {
+    my ($self, $item) = @_;
+
+    my $processable = $self->processable;
+
+    # In an upstart system, such as Ubuntu, init scripts are symlinks to
+    # upstart-job.  It doesn't make sense to check the syntax of upstart-job,
+    # so skip the checks of the init script itself in that case.
+    return
+      if $item->is_symlink
+      && $item->link eq '/lib/init/upstart-job';
+
+    return
+      unless $item->is_open_ok;
+
+    my %saw_command;
+    my %value_by_lsb_keyword;
+    my $in_file_test = 0;
+    my $needs_fs = 0;
+
+    if ($item->interpreter eq '/lib/init/init-d-script') {
+        $saw_command{$_} = 1 for qw{start stop restart force-reload status};
+    }
+
+    $self->pointed_hint('init.d-script-uses-usr-interpreter',
+        $item->pointer(1), $item->interpreter)
+      if $item->interpreter =~ m{^ /usr/ }x;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        $self->pointed_hint('init.d-script-contains-skeleton-template-content',
+            $item->pointer($position))
+          if $line =~ m{Please remove the "Author" lines|Example initscript};
+
+        if ($line =~ m/^\#\#\# BEGIN INIT INFO/) {
+
+            if (defined $value_by_lsb_keyword{BEGIN}) {
+
+                $self->pointed_hint('init.d-script-has-duplicate-lsb-section',
+                    $item->pointer($position));
+                next;
+            }
+
+            $value_by_lsb_keyword{BEGIN} = [1];
+            my $final;
+
+            # We have an LSB keyword section.  Parse it and save the data
+            # in %value_by_lsb_keyword for analysis.
+            while (my $other_line = <$fd>) {
+
+                # nested while
+                ++$position;
+
+                if ($other_line =~ /^\#\#\# END INIT INFO/) {
+                    $value_by_lsb_keyword{END} = [1];
+                    last;
+
+                } elsif ($other_line !~ /^\#/) {
+                    $self->pointed_hint(
+                        'init.d-script-has-unterminated-lsb-section',
+                        $item->pointer($position));
+                    last;
+
+                } elsif ($other_line =~ /^\# ([a-zA-Z-]+):\s*(.*?)\s*$/) {
+
+                    my $keyword = lc $1;
+                    my $value = $2 // $EMPTY;
+
+                    $self->pointed_hint(
+                        'init.d-script-has-duplicate-lsb-keyword',
+                        $item->pointer($position), $keyword)
+                      if defined $value_by_lsb_keyword{$keyword};
+
+                    $self->pointed_hint(
+                        'init.d-script-has-unknown-lsb-keyword',
+                        $item->pointer($position), $keyword)
+                      unless exists $LSB_KEYWORDS{$keyword}
+                      || $keyword =~ /^x-/;
+
+                    $value_by_lsb_keyword{$keyword} = [split($SPACE, $value)];
+                    $final = $keyword;
+
+                } elsif ($other_line =~ /^\#(\t|  )/
+                    && $final eq 'description') {
+
+                    my $value = $other_line;
+                    $value =~ s/^\#\s*//;
+                    $value_by_lsb_keyword{description} .= $SPACE . $value;
+
+                } else {
+                    $self->pointed_hint('init.d-script-has-bad-lsb-line',
+                        $item->pointer($position));
+                }
+            }
+        }
+
+        # Pretty dummy way to handle conditionals, but should be enough
+        # for simple init scripts
+        $in_file_test = 1
+          if $line
+          =~ m{ \b if \s+ .*? (?:test|\[) (?: \s+ \! )? \s+ - [efr] \s+ }x;
+
+        $in_file_test = 0
+          if $line =~ m{ \b fi \b }x;
+
+        if (  !$in_file_test
+            && $line =~ m{^\s*\.\s+["'"]?(/etc/default/[\$\w/-]+)}){
+            my $sourced = $1;
+
+            $self->pointed_hint('init.d-script-sourcing-without-test',
+                $item->pointer($position), $sourced);
+        }
+
+        # Some init.d scripts source init-d-script, since (e.g.)
+        # kFreeBSD does not allow shell scripts as interpreters.
+        if ($line =~ m{\. /lib/init/init-d-script}) {
+            $saw_command{$_} = 1
+              for qw{start stop restart force-reload status};
+        }
+
+        # This should be more sophisticated: ignore heredocs, ignore quoted
+        # text and the arguments to echo, etc.
+        $needs_fs = 1
+          if $line =~ m{^[^\#]*/var/};
+
+        while ($line =~ s/^[^\#]*?(start|stop|restart|force-reload|status)//) {
+            $saw_command{$1} = 1;
+        }
+
+        # nested while
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    # Make sure all of the required keywords are present.
+    if (!defined $value_by_lsb_keyword{BEGIN}) {
+        $self->pointed_hint('init.d-script-missing-lsb-section',
+            $item->pointer);
+
+    } else {
+        for my $keyword (keys %LSB_KEYWORDS) {
+
+            if ($LSB_KEYWORDS{$keyword}
+                && !defined $value_by_lsb_keyword{$keyword}) {
+
+                if ($keyword eq 'short-description') {
+                    $self->pointed_hint(
+                        'init.d-script-missing-lsb-short-description',
+                        $item->pointer);
+
+                } elsif ($keyword eq 'description') {
+                    next;
+
+                } else {
+                    $self->pointed_hint('init.d-script-missing-lsb-keyword',
+                        $item->pointer, $keyword);
+                }
+            }
+        }
+    }
+
+    # Check the runlevels.
+    my %start;
+
+    for my $runlevel (@{$value_by_lsb_keyword{'default-start'} // []}) {
+
+        if ($runlevel =~ /^[sS0-6]$/) {
+
+            $start{lc $runlevel} = 1;
+
+            $self->pointed_hint('init.d-script-starts-in-stop-runlevel',
+                $item->pointer, $runlevel)
+              if $runlevel eq '0'
+              || $runlevel eq '6';
+
+        } else {
+            $self->pointed_hint('init.d-script-has-bad-start-runlevel',
+                $item->pointer, $runlevel);
+        }
+    }
+
+    # No script should start at one of the 2-5 runlevels but not at
+    # all of them
+    my $start = join($SPACE, (sort grep { /^[2-5]$/ } keys %start));
+
+    if (length($start) > 0 and $start ne '2 3 4 5') {
+        my @missing = grep { !exists $start{$_} } qw(2 3 4 5);
+
+        $self->pointed_hint('init.d-script-missing-start', $item->pointer,
+            @missing);
+    }
+
+    my %stop;
+
+    for my $runlevel (@{$value_by_lsb_keyword{'default-stop'} // []}) {
+
+        if ($runlevel =~ /^[sS0-6]$/) {
+
+            $stop{$runlevel} = 1
+              unless $runlevel =~ /[sS2-5]/;
+
+            $self->pointed_hint('init.d-script-has-conflicting-start-stop',
+                $item->pointer, $runlevel)
+              if exists $start{$runlevel};
+
+            $self->pointed_hint('init-d-script-stops-in-s-runlevel',
+                $item->pointer)
+              if $runlevel =~ /[sS]/;
+
+        } else {
+            $self->pointed_hint('init.d-script-has-bad-stop-runlevel',
+                $item->pointer, $runlevel);
+        }
+    }
+
+    if (none { $item->basename eq $_ } qw(killprocs sendsigs halt reboot)) {
+
+        my @required = (0, 1, $RUN_LEVEL_6);
+        my $stop_lc = List::Compare->new(\@required, [keys %stop]);
+
+        my @have_some = $stop_lc->get_intersection;
+        my @missing = $stop_lc->get_Lonly;
+
+        # Scripts that stop in any of 0, 1, or 6 probably should stop in all
+        # of them, with some special exceptions.
+        $self->pointed_hint('init.d-script-possible-missing-stop',
+            $item->pointer, (sort @missing))
+          if @have_some
+          && @missing
+          && (%start != 1 || !exists $start{s});
+    }
+
+    my $provides_self = 0;
+    for my $facility (@{$value_by_lsb_keyword{'provides'} // []}) {
+
+        $self->pointed_hint('init.d-script-provides-virtual-facility',
+            $item->pointer, $facility)
+          if $facility =~ /^\$/;
+
+        $provides_self = 1
+          if $item->basename =~/^\Q$facility\E(?:.sh)?$/;
+    }
+
+    $self->pointed_hint('init.d-script-does-not-provide-itself',$item->pointer)
+      if defined $value_by_lsb_keyword{'provides'}
+      && !$provides_self;
+
+    # Separately check Required-Start and Required-Stop, since while they're
+    # similar, they're not quite identical.  This could use some further
+    # restructuring by pulling the regexes out as data tied to start/stop and
+    # remote/local and then combining the loops.
+    if (@{$value_by_lsb_keyword{'default-start'} // []}) {
+
+        my @required = @{$value_by_lsb_keyword{'required-start'} // []};
+
+        if ($needs_fs) {
+            if (none { /^\$(?:local_fs|remote_fs|all)\z/ } @required) {
+
+                $self->pointed_hint(
+                    'init.d-script-missing-dependency-on-local_fs',
+                    $item->pointer, 'required-start');
+            }
+        }
+    }
+
+    if (@{$value_by_lsb_keyword{'default-stop'} // []}) {
+
+        my @required = @{$value_by_lsb_keyword{'required-stop'} // []};
+
+        if ($needs_fs) {
+            if (none { /^(?:\$(?:local|remote)_fs|\$all|umountn?fs)\z/ }
+                @required) {
+
+                $self->pointed_hint(
+                    'init.d-script-missing-dependency-on-local_fs',
+                    $item->pointer, 'required-stop');
+            }
+        }
+    }
+
+    my $VIRTUAL_FACILITIES= $self->data->virtual_initd_facilities;
+
+    # Check syntax rules that apply to all of the keywords.
+    for
+      my $keyword (qw(required-start should-start required-stop should-stop)){
+        for my $prerequisite (@{$value_by_lsb_keyword{$keyword} // []}) {
+
+            if (exists $implied_dependencies{$prerequisite}) {
+
+                $self->pointed_hint('non-virtual-facility-in-initd-script',
+                    $item->pointer,
+                    "$prerequisite -> $implied_dependencies{$prerequisite}");
+
+            } elsif ($keyword =~ m/^required-/ && $prerequisite =~ m/^\$/) {
+
+                $self->pointed_hint(
+                    'init.d-script-depends-on-unknown-virtual-facility',
+                    $item->pointer, $prerequisite)
+                  unless ($VIRTUAL_FACILITIES->recognizes($prerequisite));
+            }
+
+            $self->pointed_hint(
+                'init.d-script-depends-on-all-virtual-facility',
+                $item->pointer, $keyword)
+              if $prerequisite =~ m/^\$all$/;
+        }
+    }
+
+    my @required_commands = qw{start stop restart force-reload};
+    my $command_lc
+      = List::Compare->new(\@required_commands, [keys %saw_command]);
+    my @missing_commands = $command_lc->get_Lonly;
+
+    # all tags included in file?
+    $self->pointed_hint('init.d-script-does-not-implement-required-option',
+        $item->pointer, $_)
+      for @missing_commands;
+
+    $self->pointed_hint('init.d-script-does-not-implement-status-option',
+        $item->pointer)
+      unless $saw_command{'status'};
+
+    return;
+}
+
+sub check_defaults {
+    my ($self) = @_;
+
+    my $processable = $self->processable;
+
+    my $dir = $processable->installed->resolve_path('etc/default/');
+    return
+      unless $dir && $dir->is_dir;
+
+    for my $item ($dir->children) {
+
+        return
+          unless $item->is_open_ok;
+
+        open(my $fd, '<', $item->unpacked_path)
+          or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+        my $position = 1;
+        while (my $line = <$fd>) {
+
+            $self->pointed_hint('init.d-script-should-always-start-service',
+                $item->pointer($position))
+              if $line
+              =~ m{^ \s* [#]* \s* (?:[A-Z]_)? (?:ENABLED|DISABLED|[A-Z]*RUN | (?:NO_)? START) = }x;
+
+        } continue {
+            ++$position;
+        }
+
+        close $fd;
+    }
+
+    return;
+}
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    if ($item =~ m{etc/sv/([^/]+)/$}) {
+
+        my $service = $1;
+        my $runfile
+          = $self->processable->installed->resolve_path(
+            "etc/sv/${service}/run");
+
+        $self->pointed_hint(
+            'directory-in-etc-sv-directory-without-executable-run-script',
+            $item->pointer, $runfile)
+          unless defined $runfile && $runfile->is_executable;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/InitD/MaintainerScript.pm b/lib/Lintian/Check/InitD/MaintainerScript.pm
new file mode 100644
index 0000000..b44d103
--- /dev/null
+++ b/lib/Lintian/Check/InitD/MaintainerScript.pm
@@ -0,0 +1,147 @@
+# init-d/maintainer-script -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::InitD::MaintainerScript;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_maintainer_script;
+
+    return
+      unless length $item->interpreter;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $stashed = $EMPTY;
+
+    my $saw_init = 0;
+    my $saw_invoke = 0;
+
+    my $position = 1;
+    while (my $possible_continuation = <$fd>) {
+
+        chomp $possible_continuation;
+
+        # skip empty lines
+        next
+          if $possible_continuation =~ /^\s*$/;
+
+        # skip comment lines
+        next
+          if $possible_continuation =~ /^\s*\#/;
+
+        my $no_comment = remove_comments($possible_continuation);
+
+        # Concatenate lines containing continuation character (\)
+        # at the end
+        if ($no_comment =~ s{\\$}{}) {
+
+            $stashed .= $no_comment;
+
+            next;
+        }
+
+        my $line = $stashed . $no_comment;
+        $stashed = $EMPTY;
+        # Collect information about init script invocations to
+        # catch running init scripts directly rather than through
+        # invoke-rc.d.  Since the script is allowed to run the
+        # init script directly if invoke-rc.d doesn't exist, only
+        # tag direct invocations where invoke-rc.d is never used
+        # in the same script.  Lots of false negatives, but
+        # hopefully not many false positives.
+        $saw_init = $position
+          if $line =~ m{^\s*/etc/init\.d/(?:\S+)\s+[\"\']?(?:\S+)[\"\']?};
+
+        $saw_invoke = $position
+          if $line =~ m{^\s*invoke-rc\.d\s+};
+
+    } continue {
+        ++$position;
+    }
+
+    if ($saw_init && !$saw_invoke) {
+
+        my $pointer = $item->pointer($saw_init);
+
+        $self->pointed_hint('maintainer-script-calls-init-script-directly',
+            $pointer);
+    }
+
+    return;
+}
+
+sub remove_comments {
+    my ($line) = @_;
+
+    return $line
+      unless length $line;
+
+    my $simplified = $line;
+
+    # Remove quoted strings so we can more easily ignore comments
+    # inside them
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\'(?:\\.|[^\\\'])+\'/$1''/g;
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\"(?:\\.|[^\\\"])+\"/$1""/g;
+
+    # If the remaining string contains what looks like a comment,
+    # eat it. In either case, swap the unmodified script line
+    # back in for processing (if required) and return it.
+    if ($simplified =~ m/(?:^|[^[\\])[\s\&;\(\)](\#.*$)/) {
+
+        my $comment = $1;
+
+        # eat comment
+        $line =~ s/\Q$comment\E//;
+    }
+
+    return $line;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Fortran/Gfortran.pm b/lib/Lintian/Check/Languages/Fortran/Gfortran.pm
new file mode 100644
index 0000000..6479d8a
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Fortran/Gfortran.pm
@@ -0,0 +1,94 @@
+# languages/fortran/gfortran -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Fortran::Gfortran;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+const my $NEWLINE => qq{\n};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # file-info would be great, but files are zipped
+    return
+      unless $item->name =~ m{\.mod$};
+
+    return
+      unless $item->name =~ m{^usr/lib/};
+
+    # do not look at flang, grub or libreoffice modules
+    return
+      if $item->name =~ m{/flang-\d+/}
+      || $item->name =~ m{^usr/lib/grub}
+      || $item->name =~ m{^usr/lib/libreoffice};
+
+    return
+      unless $item->is_file
+      && $item->is_open_ok
+      && $item->file_type =~ /\bgzip compressed\b/;
+
+    my $module_version;
+
+    open(my $fd, '<:gzip', $item->unpacked_path)
+      or die encode_utf8(
+        'Cannot open gz file ' . $item->unpacked_path . $NEWLINE);
+
+    while (my $line = <$fd>) {
+        next
+          if $line =~ /^\s*$/;
+
+        ($module_version) = ($line =~ /^GFORTRAN module version '(\d+)'/);
+        last;
+    }
+
+    close $fd;
+
+    unless (length $module_version) {
+        $self->pointed_hint('gfortran-module-does-not-declare-version',
+            $item->pointer);
+        return;
+    }
+
+    my $depends = $self->processable->fields->value('Depends');
+    $self->pointed_hint('missing-prerequisite-for-gfortran-module',
+        $item->pointer)
+      unless $depends =~ /\bgfortran-mod-$module_version\b/;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Golang/BuiltUsing.pm b/lib/Lintian/Check/Languages/Golang/BuiltUsing.pm
new file mode 100644
index 0000000..79095d3
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Golang/BuiltUsing.pm
@@ -0,0 +1,68 @@
+# languages/golang/built-using -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Golang::BuiltUsing;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    return
+      unless $self->processable->relation('Build-Depends')
+      ->satisfies('golang-go | golang-any');
+
+    my $control = $self->processable->debian_control;
+
+    for my $installable ($control->installables) {
+        my $installable_fields= $control->installable_fields($installable);
+
+        my $control_item= $self->processable->debian_control->item;
+        my $position = $installable_fields->position('Package');
+
+        $self->pointed_hint(
+            'missing-built-using-field-for-golang-package',
+            $control_item->pointer($position),
+            "(in section for $installable)"
+          )
+          if $installable_fields->value('Built-Using')
+          !~ m{ \$ [{] misc:Built-Using [}] }x
+          && $installable_fields->value('Architecture') ne 'all';
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Golang/ImportPath.pm b/lib/Lintian/Check/Languages/Golang/ImportPath.pm
new file mode 100644
index 0000000..210696b
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Golang/ImportPath.pm
@@ -0,0 +1,56 @@
+# languages/golang/import-path -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Golang::ImportPath;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    return
+      unless $self->processable->relation('Build-Depends')
+      ->satisfies('golang-go | golang-any');
+
+    my $control = $self->processable->debian_control;
+    my $source_fields = $control->source_fields;
+
+    $self->hint('missing-xs-go-import-path-for-golang-package')
+      unless $source_fields->declares('XS-Go-Import-Path');
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Java.pm b/lib/Lintian/Check/Languages/Java.pm
new file mode 100644
index 0000000..4b26512
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Java.pm
@@ -0,0 +1,315 @@
+# languages/java -- lintian check script -*- perl -*-
+
+# Copyright (C) 2011 Vincent Fourmond
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Java;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use File::Basename;
+use List::SomeUtils qw(any none);
+
+use Lintian::Util qw(normalize_link_target $PKGNAME_REGEX $PKGVERSION_REGEX);
+
+const my $EMPTY => q{};
+const my $HYPHEN => q{-};
+
+const my $ARROW => q{->};
+
+const my $BYTE_CODE_VERSION_OFFSET => 44;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+our $CLASS_REGEX = qr/\.(?:class|cljc?)/;
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    my $java_info = $item->java_info;
+    return
+      unless scalar keys %{$java_info};
+
+    my $files = $java_info->{files};
+
+    $self->pointed_hint('source-contains-prebuilt-java-object', $item->pointer)
+      if any { m/$CLASS_REGEX$/i } keys %{$files};
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $missing_jarwrapper = 0;
+    my $has_public_jars = 0;
+    my $jmajlow = $HYPHEN;
+
+    my $depends = $self->processable->relation('strong')->to_string;
+
+    # Remove all libX-java-doc packages to avoid thinking they are java libs
+    #  - note the result may not be a valid dependency listing
+    $depends =~ s/lib[^\s,]+-java-doc//g;
+
+    my @java_lib_depends = ($depends =~ m/\b(lib[^\s,]+-java)\b/g);
+
+    my $JAVA_BYTECODES= $self->data->load('java/constants', qr/\s*=\s*/);
+
+    # We first loop over jar files to find problems
+
+    for my $item (@{$self->processable->installed->sorted_list}) {
+
+        my $java_info = $item->java_info;
+        next
+          unless scalar keys %{$java_info};
+
+        my $files = $java_info->{files};
+        my $manifest = $java_info->{manifest};
+        my $jar_dir = dirname($item->name);
+        my $classes = 0;
+        my $datafiles = 1;
+        my $class_path = $EMPTY;
+        my $bsname = $EMPTY;
+
+        if (exists $java_info->{error}) {
+            $self->pointed_hint('zip-parse-error', $item->pointer,
+                $java_info->{error});
+            next;
+        }
+
+        # The Java Policy says very little about requires for (jars in) JVMs
+        next
+          if $item->name =~ m{^usr/lib/jvm(?:-exports)?/[^/]+/};
+
+        # Ignore Mozilla's jar files, see #635495
+        next
+          if $item->name =~ m{^usr/lib/xul(?:-ext|runner[^/]*+)/};
+
+        if ($item->name =~ m{^usr/share/java/[^/]+\.jar$}) {
+            $has_public_jars = 1;
+
+            # java policy requires package version too; see Bug#976681
+            $self->pointed_hint('bad-jar-name', $item->pointer)
+              unless basename($item->name)
+              =~ /^$PKGNAME_REGEX-$PKGVERSION_REGEX\.jar$/;
+        }
+
+        # check for common code files like .class or .clj (Clojure files)
+        for my $class (grep { m/$CLASS_REGEX$/i } sort keys %{$files}){
+
+            my $module_version = $files->{$class};
+            (my $src = $class) =~ s/\.[^.]+$/\.java/;
+
+            $self->pointed_hint('jar-contains-source', $item->pointer, $src)
+              if %{$files}{$src};
+
+            $classes = 1;
+
+            next
+              if $class =~ m/\.cljc?$/;
+
+            # .class but no major version?
+            next
+              if $module_version eq $HYPHEN;
+
+            if ($module_version
+                < $JAVA_BYTECODES->value('lowest-known-bytecode-version')
+                || $module_version
+                > $JAVA_BYTECODES->value('highest-known-bytecode-version')) {
+
+                # First public major version was 45 (Java1), latest
+                # version is 55 (Java11).
+                $self->pointed_hint('unknown-java-class-version',
+                    $item->pointer,$class, $ARROW, $module_version);
+
+                # Skip the rest of this Jar.
+                last;
+            }
+
+            # Collect the "lowest" Class version used.  We assume that
+            # mixed class formats implies special compat code for certain
+            # JVM cases.
+            if ($jmajlow eq $HYPHEN) {
+                # first;
+                $jmajlow = $module_version;
+
+            } else {
+                $jmajlow = $module_version
+                  if $module_version < $jmajlow;
+            }
+        }
+
+        $datafiles = 0
+          if none { /\.(?:xml|properties|x?html|xhp)$/i } keys %{$files};
+
+        if ($item->is_executable) {
+
+            $self->pointed_hint('executable-jar-without-main-class',
+                $item->pointer)
+              unless $manifest && $manifest->{'Main-Class'};
+
+            # Here, we need to check that the package depends on
+            # jarwrapper.
+            $missing_jarwrapper = 1
+              unless $self->processable->relation('strong')
+              ->satisfies('jarwrapper');
+
+        } elsif ($item->name !~ m{^usr/share/}) {
+
+            $self->pointed_hint('jar-not-in-usr-share', $item->pointer);
+        }
+
+        $class_path = $manifest->{'Class-Path'}//$EMPTY if $manifest;
+        $bsname = $manifest->{'Bundle-SymbolicName'}//$EMPTY if $manifest;
+
+        if ($manifest) {
+            if (!$classes) {
+
+               # Eclipse / OSGi bundles are sometimes source bundles
+               #   these do not ship classes but java files and other sources.
+               # Javadoc jars deployed in the Maven repository also do not ship
+               #   classes but HTML files, images and CSS files
+                if (
+                    (
+                        $bsname !~ m/\.source$/
+                        && $item->name
+                        !~ m{^usr/share/maven-repo/.*-javadoc\.jar}
+                        && $item->name !~ m{\.doc(?:\.(?:user|isv))?_[^/]+.jar}
+                        && $item->name !~ m{\.source_[^/]+.jar}
+                    )
+                    || $class_path
+                ) {
+                    $self->pointed_hint('codeless-jar', $item->pointer);
+                }
+            }
+
+        } elsif ($classes) {
+            $self->pointed_hint('missing-manifest', $item->pointer);
+        }
+
+        if ($class_path) {
+            # Only run the tests when a classpath is present
+            my @relative;
+            my @paths = split(m/\s++/, $class_path);
+            for my $p (@paths) {
+                if ($p) {
+                    # Strip leading ./
+                    $p =~ s{^\./+}{}g;
+                    if ($p !~ m{^(?:file://)?/} && $p =~ m{/}) {
+                        my $target = normalize_link_target($jar_dir, $p);
+                        my $tinfo;
+                        # Can it be normalized?
+                        next unless defined($target);
+                        # Relative link to usr/share/java ? Works if
+                        # we are depending of a Java library.
+                        next
+                          if $target =~ m{^usr/share/java/[^/]+.jar$}
+                          && @java_lib_depends;
+                        $tinfo= $self->processable->installed->lookup($target);
+                        # Points to file or link in this package,
+                        #  which is sometimes easier than
+                        #  re-writing the classpath.
+                        next
+                          if defined $tinfo
+                          and ($tinfo->is_symlink or $tinfo->is_file);
+                        # Relative path with subdirectories.
+                        push @relative, $p;
+                    }
+                    # @todo add an info tag for relative paths, to educate
+                    # maintainers ?
+                }
+            }
+
+            $self->pointed_hint('classpath-contains-relative-path',
+                $item->pointer, join(', ', @relative))
+              if @relative;
+        }
+
+        # Trigger a warning when a maven plugin lib is installed in
+        # /usr/share/java/
+        $self->pointed_hint('maven-plugin-in-usr-share-java', $item->pointer)
+          if    $has_public_jars
+          && $self->processable->name =~ /^lib.*maven.*plugin.*/
+          && $item->name !~ m{^usr/share/maven-repo/.*\.jar};
+    }
+
+    $self->hint('missing-dep-on-jarwrapper') if $missing_jarwrapper;
+
+    if ($jmajlow ne $HYPHEN) {
+        # Byte code numbers:
+        #  45-49 -> Java1 - Java5 (Always ok)
+        #     50 -> Java6
+        #     51 -> Java7
+        #     52 -> Java8
+        #     53 -> Java9
+        #     54 -> Java10
+        #     55 -> Java11
+        my $bad = 0;
+
+        # If the lowest version used is greater than the requested
+        # limit, then flag it.
+        $bad = 1
+          if $jmajlow > $JAVA_BYTECODES->value('default-bytecode-version');
+
+        # Technically we ought to do some checks with Java6 class
+        # files and dependencies/package types, but for now just skip
+        # that.  (See #673276)
+
+        if ($bad) {
+            # Map the Class version to a Java version.
+            my $java_version = $jmajlow - $BYTE_CODE_VERSION_OFFSET;
+
+            $self->hint('incompatible-java-bytecode-format',
+                "Java$java_version version (Class format: $jmajlow)");
+        }
+    }
+
+    if (   !$has_public_jars
+        && !$self->processable->is_transitional
+        && $self->processable->name =~ /^lib[^\s,]+-java$/){
+
+        # Skip this if it installs a symlink in usr/share/java
+        my $java_dir
+          = $self->processable->installed->resolve_path('usr/share/java/');
+
+        my $has_jars = 0;
+        $has_jars = 1
+          if $java_dir
+          && (any { $_->name =~ m{^[^/]+\.jar$} } $java_dir->children);
+
+        $self->hint('javalib-but-no-public-jars')
+          unless $has_jars;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Java/Bytecode.pm b/lib/Lintian/Check/Languages/Java/Bytecode.pm
new file mode 100644
index 0000000..14566a9
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Java/Bytecode.pm
@@ -0,0 +1,58 @@
+# languages/java/bytecode -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Java::Bytecode;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $MAGIC_BYTE_SIZE => 4;
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # .class (compiled Java files)
+    if (   $item->name =~ /\.class$/
+        && $item->name !~ /(?:WEB-INF|demo|doc|example|sample|test)/) {
+
+        my $magic = $item->magic($MAGIC_BYTE_SIZE);
+
+        $self->pointed_hint('package-installs-java-bytecode', $item->pointer)
+          if $magic eq "\xCA\xFE\xBA\xBE";
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Javascript/Embedded.pm b/lib/Lintian/Check/Languages/Javascript/Embedded.pm
new file mode 100644
index 0000000..9227187
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Javascript/Embedded.pm
@@ -0,0 +1,149 @@
+# languages/javascript/embedded -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Javascript::Embedded;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+my %JS_MAGIC
+  = ('libjs-bootstrap' => qr{ var [ ] (?: Carousel | Typeahead ) }x,);
+
+my $JS_EXT
+  = qr{(?:(?i)[-._]?(?:compiled|lite|min|pack(?:ed)?|prod|umd|yc)?\.(js|css)(?:\.gz)?)$};
+my %JS_FILES = (
+    'ckeditor' => qr{(?i)/ckeditor} . $JS_EXT,
+    'fckeditor' => qr{(?i)/fckeditor} . $JS_EXT,
+    'libjs-async' => qr{(?i)/async} . $JS_EXT,
+    'libjs-bootstrap' => qr{(?i)/bootstrap(?:-[\d\.]+)?} . $JS_EXT,
+    'libjs-chai'      => qr{(?i)/chai} . $JS_EXT,
+    'libjs-cropper'   => qr{(?i)/cropper(?:\.uncompressed)?} . $JS_EXT,
+    'libjs-dojo-\w+'  => qr{(?i)/(?:dojo|dijit)} . $JS_EXT,
+    'libjs-excanvas'  => qr{(?i)/excanvas(?:-r[0-9]+)?} . $JS_EXT,
+    'libjs-jac'       => qr{(?i)/jsjac} . $JS_EXT,
+    'libjs-jquery'    => qr{(?i)/jquery(?:-[\d\.]+)?} . $JS_EXT,
+    'libjs-jquery-cookie' => qr{(?i)/jquery\.cookie} . $JS_EXT,
+    'libjs-jquery-easing' => qr{(?i)/jquery\.easing} . $JS_EXT,
+    'libjs-jquery-event-drag' => qr{(?i)/jquery\.event\.drap} . $JS_EXT,
+    'libjs-jquery-event-drop' => qr{(?i)/jquery\.event\.drop} . $JS_EXT,
+    'libjs-jquery-fancybox'   => qr{(?i)/jquery\.fancybox} . $JS_EXT,
+    'libjs-jquery-form'       => qr{(?i)/jquery\.form} . $JS_EXT,
+    'libjs-jquery-galleriffic' => qr{(?i)/jquery\.galleriffic} . $JS_EXT,
+    'libjs-jquery-history'     => qr{(?i)/jquery\.history} . $JS_EXT,
+    'libjs-jquery-jfeed'       => qr{(?i)/jquery\.jfeed} . $JS_EXT,
+    'libjs-jquery-jush'        => qr{(?i)/jquery\.jush} . $JS_EXT,
+    'libjs-jquery-livequery'   => qr{(?i)/jquery\.livequery} . $JS_EXT,
+    'libjs-jquery-meiomask'    => qr{(?i)/jquery\.meiomask} . $JS_EXT,
+    'libjs-jquery-metadata'    => qr{(?i)/jquery\.metadata} . $JS_EXT,
+    'libjs-jquery-migrate-1'   => qr{(?i)/jquery-migrate(?:-1[\d\.]*)}
+      . $JS_EXT,
+    'libjs-jquery-mousewheel'  => qr{(?i)/jquery\.mousewheel} . $JS_EXT,
+    'libjs-jquery-opacityrollover' => qr{(?i)/jquery\.opacityrollover}
+      . $JS_EXT,
+    'libjs-jquery-tablesorter'     => qr{(?i)/jquery\.tablesorter} . $JS_EXT,
+    'libjs-jquery-tipsy'           => qr{(?i)/jquery\.tipsy} . $JS_EXT,
+    'libjs-jquery-treetable'       => qr{(?i)/jquery\.treetable} . $JS_EXT,
+    'libjs-jquery-ui'              => qr{(?i)/jquery[\.-](?:-[\d\.]+)?ui}
+      . $JS_EXT,
+    'libjs-mocha'                  => qr{(?i)/mocha} . $JS_EXT,
+    'libjs-mochikit'               => qr{(?i)/mochikit} . $JS_EXT,
+    'libjs-mootools'               =>
+qr{(?i)/mootools(?:(?:\.v|-)[\d\.]+)?(?:-(?:(?:core(?:-server)?)|more)(?:-(?:yc|jm|nc))?)?}
+      . $JS_EXT,
+    'libjs-mustache'               => qr{(?i)/mustache} . $JS_EXT,
+# libjs-normalize is provided by node-normalize.css but this is an implementation detail
+    'libjs-normalize'              => qr{(?i)/normalize(?:\.min)?\.css},
+    'libjs-prototype'              => qr{(?i)/prototype(?:-[\d\.]+)?}. $JS_EXT,
+    'libjs-raphael'                => qr{(?i)/raphael(?:[\.-]min)?} . $JS_EXT,
+    'libjs-scriptaculous'          => qr{(?i)/scriptaculous} . $JS_EXT,
+    'libjs-strophe'                => qr{(?i)/strophe} . $JS_EXT,
+    'libjs-underscore'             => qr{(?i)/underscore} . $JS_EXT,
+    'libjs-yui'                    => qr{(?i)/(?:yahoo|yui)-(?:dom-event)?}
+      . $JS_EXT,
+    # Disabled due to false positives.  Needs a content check adding to verify
+    # that the file being checked is /the/ yahoo.js
+    # 'libjs-yui'                  => qr{(?i)/yahoo\.js(\.gz)?} . $JS_EXT,
+    'jsmath'                       => qr{(?i)/jsMath(?:-fallback-\w+)?}
+      . $JS_EXT,
+    'node-html5shiv'               => qr{(?i)html5shiv(?:-printshiv)?}
+      . $JS_EXT,
+    'sphinx'                       =>
+      qr{(?i)/_static/(?:doctools|language_data|searchtools)} . $JS_EXT,
+    'tinymce'                      => qr{(?i)/tiny_mce(?:_(?:popup|src))?}
+      . $JS_EXT,
+    'libjs-lodash'                 => qr{(?i)lodash} . $JS_EXT,
+    'node-pako'                    =>
+      qr{(?i)pako(?:_(:?de|in)flate(?:.es\d+)?)(?:-[\d\.]+)?}. $JS_EXT,
+    'node-jszip-utils'             => qr{(?i)jszip-utils(?:-ie)?(?:-[\d\.]+)?}
+      . $JS_EXT,
+    'node-jszip'             => qr{(?i)jszip(?:-ie)?(?:-[\d\.]+)?} . $JS_EXT,
+    'libjs-codemirror'       => qr{(?i)codemirror} . $JS_EXT,
+    'libjs-punycode'         => qr{(?i)punycode(?:\.es\d+)?} . $JS_EXT,
+# not yet available in unstable
+# 'xinha'                      => qr{(?i)/(htmlarea|Xinha(Loader|Core))} . $JS_EXT,
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # ignore embedded jQuery libraries for Doxygen (#736360)
+    my $doxygen = $self->processable->installed->resolve_path(
+        $item->dirname . 'doxygen.css');
+    return
+      if $item->basename eq 'jquery.js'
+      && defined $doxygen;
+
+    # embedded javascript
+    for my $provider (keys %JS_FILES) {
+
+        next
+          if $self->processable->name =~ /^$provider$/;
+
+        next
+          unless $item->name =~ /$JS_FILES{$provider}/;
+
+        next
+          if length $JS_MAGIC{$provider}
+          && !length $item->bytes_match($JS_MAGIC{$provider});
+
+        $self->pointed_hint('embedded-javascript-library', $item->pointer,
+            'please use', $provider);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Javascript/Nodejs.pm b/lib/Lintian/Check/Languages/Javascript/Nodejs.pm
new file mode 100644
index 0000000..98a5d76
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Javascript/Nodejs.pm
@@ -0,0 +1,262 @@
+# languages/javascript/nodejs -- lintian check script -*- perl -*-
+
+# Copyright (C) 2019-2020, Xavier Guimard <yadd@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Javascript::Nodejs;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use JSON::MaybeXS;
+use List::SomeUtils qw(any none first_value);
+use Path::Tiny;
+use Syntax::Keyword::Try;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Relation;
+
+const my $SLASH => q{/};
+const my $DOT => q{.};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $debian_control = $self->processable->debian_control;
+
+    # debian/control check
+    my @testsuites
+      = split(m/\s*,\s*/,$debian_control->source_fields->value('Testsuite'));
+
+    if (any { $_ eq 'autopkgtest-pkg-nodejs' } @testsuites) {
+
+        my $item = $self->processable->patched->resolve_path(
+            'debian/tests/pkg-js/test');
+        if (defined $item) {
+
+            $self->pointed_hint('pkg-js-autopkgtest-test-is-empty',
+                $item->pointer)
+              if none { /^[^#]*\w/m } $item->bytes;
+
+        } else {
+            $self->hint('pkg-js-autopkgtest-test-is-missing');
+        }
+
+        # Ensure all files referenced in debian/tests/pkg-js/files exist
+        my $files
+          = $self->processable->patched->resolve_path(
+            'debian/tests/pkg-js/files');
+        if (defined $files) {
+
+            my @patterns = path($files->unpacked_path)->lines;
+
+            # trim leading and trailing whitespace
+            s/^\s+|\s+$//g for @patterns;
+
+            my @notfound = grep { !$self->path_exists($_) } @patterns;
+
+            $self->hint('pkg-js-autopkgtest-file-does-not-exist', $_)
+              for @notfound;
+        }
+    }
+
+    # debian/rules check
+    my $droot = $self->processable->patched->resolve_path('debian/')
+      or return;
+    my $drules = $droot->child('rules')
+      or return;
+
+    return
+      unless $drules->is_open_ok;
+
+    open(my $rules_fd, '<', $drules->unpacked_path)
+      or die encode_utf8('Cannot open ' . $drules->unpacked_path);
+
+    my $command_prefix_pattern = qr/\s+[@+-]?(?:\S+=\S+\s+)*/;
+    my ($seen_nodejs,$override_test,$seen_dh_dynamic);
+    my $bdepends = $self->processable->relation('Build-Depends-All');
+    $seen_nodejs = 1 if $bdepends->satisfies('dh-sequence-nodejs');
+
+    while (my $line = <$rules_fd>) {
+
+        # reconstitute splitted lines
+        while ($line =~ s/\\$// && defined(my $cont = <$rules_fd>)) {
+            $line .= $cont;
+        }
+
+        # skip comments
+        next
+          if $line =~ /^\s*\#/;
+
+        if ($line =~ m{^(?:$command_prefix_pattern)dh\s+}) {
+            $seen_dh_dynamic = 1
+              if $line =~ /\$[({]\w/;
+
+            while ($line =~ /\s--with(?:=|\s+)(['"]?)(\S+)\1/g) {
+                my @addons = split(m{,}, $2);
+                $seen_nodejs = 1
+                  if any { $_ eq 'nodejs' } @addons;
+            }
+
+        } elsif ($line =~ /^([^:]*override_dh_[^:]*):/) {
+            $override_test = 1
+              if $1 eq 'auto_test';
+        }
+    }
+
+    if(    $seen_nodejs
+        && !$override_test
+        && !$seen_dh_dynamic) {
+
+        # pkg-js-tools search build test in the following order
+        my @candidates = qw{debian/nodejs/test debian/tests/pkg-js/test};
+
+        my $item = first_value { defined }
+        map { $self->processable->patched->resolve_path($_) } @candidates;
+
+        # Ensure test file contains something
+        if (defined $item) {
+            $self->pointed_hint('pkg-js-tools-test-is-empty', $item->pointer)
+              unless any { /^[^#]*\w/m } $item->bytes;
+
+        } else {
+            $self->hint('pkg-js-tools-test-is-missing');
+        }
+    }
+
+    return;
+}
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      if $item->is_dir;
+
+    return
+      if $self->processable->name =~ /-dbg$/;
+
+    # Warn if a file is installed in old nodejs root dir
+    $self->pointed_hint('nodejs-module-installed-in-usr-lib', $item->pointer)
+      if $item->name =~ m{^usr/lib/nodejs/.*};
+
+    # Warn if package is not installed in a subdirectory of nodejs root
+    # directories
+    $self->pointed_hint('node-package-install-in-nodejs-rootdir',
+        $item->pointer)
+      if $item->name
+      =~ m{^usr/(?:share|lib(?:/[^/]+)?)/nodejs/(?:package\.json|[^/]*\.js)$};
+
+    # Now we have to open package.json
+    return
+      unless $item->is_open_ok;
+
+    # Return an error if a package-lock.json or a yanr.lock file is installed
+    $self->pointed_hint('nodejs-lock-file', $item->pointer)
+      if $item->name
+      =~ m{^usr/(?:share|lib(?:/[^/]+)?)/nodejs/([^/]+)(.*/)(package-lock\.json|yarn\.lock)$};
+
+    # Look only nodejs package.json files
+    return
+      unless $item->name
+      =~ m{^usr/(?:share|lib(?:/[^/]+)?)/nodejs/([^\@/]+|\@[^/]+/[^/]+)(.*/)package\.json$};
+
+    # First regexp arg: directory in /**/nodejs or @foo/bar when dir starts
+    #                   with '@', following npm registry policy
+    my $dirname = $1;
+    # Second regex arg: subpath in /**/nodejs/module/ (eg: node_modules/foo)
+    my $subpath = $2;
+
+    my $declared = $self->processable->name;
+    my $version = $self->processable->fields->value('Version');
+    $declared .= "( = $version)"
+      if length $version;
+    $version ||= '0-1';
+
+    my $provides
+      = $self->processable->relation('Provides')->logical_and($declared);
+
+    my $content = $item->bytes;
+
+    # Look only valid package.json files
+    my $pac;
+    try {
+        $pac = decode_json($content);
+        die
+          unless length $pac->{name};
+    } catch {
+        return;
+    }
+
+    # Store node module name & version (classification)
+    $self->pointed_hint('nodejs-module', $item->pointer, $pac->{name},
+        $pac->{version} // 'undef');
+
+    # Warn if version is 0.0.0-development
+    $self->pointed_hint('nodejs-missing-version-override',
+        $item->pointer, $pac->{name}, $pac->{version})
+      if $pac->{version} and $pac->{version} =~ /^0\.0\.0-dev/;
+
+    # Warn if module name is not equal to nodejs directory
+    if ($subpath eq $SLASH && $dirname ne $pac->{name}) {
+        $self->pointed_hint('nodejs-module-installed-in-bad-directory',
+            $item->pointer, $pac->{name}, $dirname);
+
+    } else {
+        # Else verify that module is declared at least in Provides: field
+        my $name = 'node-' . lc($pac->{name});
+        # Normalize name following Debian policy
+        # (replace invalid characters by "-")
+        $name =~ s{[/_\@]}{-}g;
+        $name =~ s/-+/-/g;
+
+        $self->pointed_hint('nodejs-module-not-declared', $item->pointer,$name)
+          if $subpath eq $SLASH
+          && !$provides->satisfies($name);
+    }
+
+    return;
+}
+
+sub path_exists {
+    my ($self, $expression) = @_;
+
+    # replace asterisks with proper regex wildcard
+    $expression =~ s{ [*] }{[^/]*}gsx;
+
+    return 1
+      if any { m{^ $expression /? $}sx }
+      @{$self->processable->patched->sorted_list};
+
+    return 0;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Ocaml/ByteCode/Compiled.pm b/lib/Lintian/Check/Languages/Ocaml/ByteCode/Compiled.pm
new file mode 100644
index 0000000..f916d68
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Ocaml/ByteCode/Compiled.pm
@@ -0,0 +1,85 @@
+# languages/ocaml/byte-code/compiled -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2009 Stephane Glondu
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Ocaml::ByteCode::Compiled;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has provided_o => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %provided_o;
+
+        for my $item (@{$self->processable->installed->sorted_list}) {
+
+            for my $count (keys %{$item->ar_info}) {
+
+                my $member = $item->ar_info->{$count}{name};
+                next
+                  unless length $member;
+
+                # dirname ends in a slash
+                my $virtual_path = $item->dirname . $member;
+
+                # Note: a .o may be legitimately in several different .a
+                $provided_o{$virtual_path} = $item->name;
+            }
+        }
+
+        return \%provided_o;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    my $no_extension = $item->basename;
+    $no_extension =~ s{ [.] [^.]+ $}{}x;
+
+    # The .cmx counterpart: for each .cmx file, there must be a
+    # matching .o file, which can be there by itself, or embedded in a
+    # .a file in the same directory
+    # dirname ends with a slash
+    $self->pointed_hint('ocaml-dangling-cmx', $item->pointer)
+      if $item->name =~ m{ [.]cmx $}x
+      && !$item->parent_dir->child($no_extension . '.o')
+      && !exists $self->provided_o->{$item->dirname . $no_extension . '.o'};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Ocaml/ByteCode/Interface.pm b/lib/Lintian/Check/Languages/Ocaml/ByteCode/Interface.pm
new file mode 100644
index 0000000..8edeab1
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Ocaml/ByteCode/Interface.pm
@@ -0,0 +1,63 @@
+# languages/ocaml/byte-code/interface -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2009 Stephane Glondu
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Ocaml::ByteCode::Interface;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $LAST_ITEM => -1;
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    my $no_extension = $item->basename;
+    $no_extension =~ s{ [.] [^.]+ $}{}x;
+
+    # for dune
+    my $interface_name = (split(/__/, $no_extension))[$LAST_ITEM];
+
+    # $somename.cmi should be shipped with $somename.mli or $somename.ml
+    $self->pointed_hint('ocaml-dangling-cmi', $item->pointer)
+      if $item->name =~ m{ [.]cmi $}x
+      && !$item->parent_dir->child($interface_name . '.mli')
+      && !$item->parent_dir->child(lc($interface_name) . '.mli')
+      && !$item->parent_dir->child($interface_name . '.ml')
+      && !$item->parent_dir->child(lc($interface_name) . '.ml');
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Ocaml/ByteCode/Library.pm b/lib/Lintian/Check/Languages/Ocaml/ByteCode/Library.pm
new file mode 100644
index 0000000..965f134
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Ocaml/ByteCode/Library.pm
@@ -0,0 +1,58 @@
+# languages/ocaml/byte-code/library -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2009 Stephane Glondu
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Ocaml::ByteCode::Library;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    my $no_extension = $item->basename;
+    $no_extension =~ s{ [.] [^.]+ $}{}x;
+
+    # For each .cmxa file, there must be a matching .a file (#528367)
+    $self->pointed_hint('ocaml-dangling-cmxa', $item->pointer)
+      if $item->name =~ m{ [.]cmxa $}x
+      && !$item->parent_dir->child($no_extension . '.a');
+
+    # $somename.cmo should usually not be shipped with $somename.cma
+    $self->pointed_hint('ocaml-stray-cmo', $item->pointer)
+      if $item->name =~ m{ [.]cma $}x
+      && $item->parent_dir->child($no_extension . '.cmo');
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Ocaml/ByteCode/Misplaced/Package.pm b/lib/Lintian/Check/Languages/Ocaml/ByteCode/Misplaced/Package.pm
new file mode 100644
index 0000000..767f6b0
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Ocaml/ByteCode/Misplaced/Package.pm
@@ -0,0 +1,126 @@
+# languages/ocaml/byte-code/misplaced/package -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2009 Stephane Glondu
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Ocaml::ByteCode::Misplaced::Package;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(first_value);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $SLASH => q{/};
+
+has development_files => (is => 'rw', default => sub { [] });
+
+has is_dev_package => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        # is it a development package?
+        return 1
+          if (
+            $self->processable->name =~ m{
+           (?: -dev
+              |\A camlp[45](?:-extra)?
+              |\A ocaml  (?:
+                     -nox
+                    |-interp
+                    |-compiler-libs
+                  )?
+           )\Z}xsm
+          );
+
+        return 0;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # .cma, .cmo and .cmxs are excluded because they can be plugins
+    push(@{$self->development_files}, $item->name)
+      if $item->name =~ m{ [.] cm (?: i | xa? ) $}x;
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $count = scalar @{$self->development_files};
+    my $plural = ($count == 1) ? $EMPTY : 's';
+
+    my $prefix = longest_common_prefix(@{$self->development_files});
+
+    # strip trailing slash
+    $prefix =~ s{ / $}{}x
+      unless $prefix eq $SLASH;
+
+    # non-dev packages should not ship .cmi, .cmx or .cmxa files
+    $self->hint('ocaml-dev-file-in-nondev-package',
+        "$count file$plural in $prefix")
+      if $count > 0
+      && !$self->is_dev_package;
+
+    return;
+}
+
+sub longest_common_prefix {
+    my (@paths) = @_;
+
+    my %prefixes;
+
+    for my $path (@paths) {
+
+        my $truncated = $path;
+
+        # first operation drops the file name
+        while ($truncated =~ s{ / [^/]* $}{}x) {
+            ++$prefixes{$truncated};
+        }
+    }
+
+    my @by_descending_length = reverse sort keys %prefixes;
+
+    my $common = first_value { $prefixes{$_} == @paths } @by_descending_length;
+
+    $common ||= $SLASH;
+
+    return $common;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Ocaml/ByteCode/Misplaced/Path.pm b/lib/Lintian/Check/Languages/Ocaml/ByteCode/Misplaced/Path.pm
new file mode 100644
index 0000000..68e4f4f
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Ocaml/ByteCode/Misplaced/Path.pm
@@ -0,0 +1,105 @@
+# languages/ocaml/byte-code/misplaced/path -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2009 Stephane Glondu
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Ocaml::ByteCode::Misplaced::Path;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(first_value);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $SLASH => q{/};
+
+has misplaced_files => (is => 'rw', default => sub { [] });
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # development files outside /usr/lib/ocaml (.cmi, .cmx, .cmxa)
+    return
+      if $item->name =~ m{^ usr/lib/ocaml/ }x;
+
+    # .cma, .cmo and .cmxs are excluded because they can be plugins
+    push(@{$self->misplaced_files}, $item->name)
+      if $item->name =~ m{ [.] cm (?: i | xa? ) $}x;
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $count = scalar @{$self->misplaced_files};
+    my $plural = ($count == 1) ? $EMPTY : 's';
+
+    my $prefix = longest_common_prefix(@{$self->misplaced_files});
+
+    # strip trailing slash
+    $prefix =~ s{ / $}{}x
+      unless $prefix eq $SLASH;
+
+    $self->hint(
+        'ocaml-dev-file-not-in-usr-lib-ocaml',
+        "$count file$plural in $prefix"
+    )if $count > 0;
+
+    return;
+}
+
+sub longest_common_prefix {
+    my (@paths) = @_;
+
+    my %prefixes;
+
+    for my $path (@paths) {
+
+        my $truncated = $path;
+
+        # first operation drops the file name
+        while ($truncated =~ s{ / [^/]* $}{}x) {
+            ++$prefixes{$truncated};
+        }
+    }
+
+    my @by_descending_length = reverse sort keys %prefixes;
+
+    my $common = first_value { $prefixes{$_} == @paths } @by_descending_length;
+
+    $common ||= $SLASH;
+
+    return $common;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Ocaml/ByteCode/Plugin.pm b/lib/Lintian/Check/Languages/Ocaml/ByteCode/Plugin.pm
new file mode 100644
index 0000000..ae14f6b
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Ocaml/ByteCode/Plugin.pm
@@ -0,0 +1,56 @@
+# languages/ocaml/byte-code/plugin -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2009 Stephane Glondu
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Ocaml::ByteCode::Plugin;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    my $no_extension = $item->basename;
+    $no_extension =~ s{ [.] [^.]+ $}{}x;
+
+    # For each .cmxs file, there must be a matching .cma or .cmo file
+    # (at least, in library packages)
+    $self->pointed_hint('ocaml-dangling-cmxs', $item->pointer)
+      if $item->name =~ m{ [.]cmxs $}x
+      && !$item->parent_dir->child($no_extension . '.cma')
+      && !$item->parent_dir->child($no_extension . '.cmo')
+      && $self->processable->name =~ /^lib/;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Ocaml/CustomExecutable.pm b/lib/Lintian/Check/Languages/Ocaml/CustomExecutable.pm
new file mode 100644
index 0000000..8ebad48
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Ocaml/CustomExecutable.pm
@@ -0,0 +1,59 @@
+# languages/ocaml/custom-executable -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Ocaml::CustomExecutable;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /^ [^,]* \b ELF \b /x;
+
+    # Check for OCaml custom executables (#498138)
+    $self->pointed_hint('ocaml-custom-executable', $item->pointer)
+      if $item->file_type =~ m{ \b not [ ] stripped \b }x
+      && $item->file_type =~ m{ \b executable \b }x
+      && $item->strings =~ m{^ Caml1999X0 [0-9] [0-9] $}mx;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Ocaml/Meta.pm b/lib/Lintian/Check/Languages/Ocaml/Meta.pm
new file mode 100644
index 0000000..0a9976b
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Ocaml/Meta.pm
@@ -0,0 +1,67 @@
+# languages/ocaml/meta -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2009 Stephane Glondu
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Ocaml::Meta;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has has_meta => (is => 'rw', default => 0);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->name =~ m{^ usr/lib/ocaml/ }x;
+
+    # does the package provide a META file?
+    $self->has_meta(1)
+      if $item->name =~ m{ / META (?: [.] | $ ) }x;
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $prerequisites = $self->processable->relation('all');
+
+    # If there is a META file, ocaml-findlib should at least be suggested.
+    $self->hint('ocaml-meta-without-suggesting-findlib')
+      if $self->has_meta
+      && !$prerequisites->satisfies('ocaml-findlib:any');
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Perl.pm b/lib/Lintian/Check/Languages/Perl.pm
new file mode 100644
index 0000000..c68af47
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Perl.pm
@@ -0,0 +1,125 @@
+# languages/perl -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Perl;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has perl_sources_in_lib => (is => 'rw', default => sub { [] });
+has has_perl_binaries => (is => 'rw', default => 0);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # perllocal.pod
+    $self->pointed_hint('package-installs-perllocal-pod', $item->pointer)
+      if $item->name =~ m{^usr/lib/perl.*/perllocal.pod$};
+
+    # .packlist files
+    if ($item->name =~ m{^usr/lib/perl.*/.packlist$}) {
+        $self->pointed_hint('package-installs-packlist', $item->pointer);
+
+    }elsif ($item->name =~ m{^usr/lib/(?:[^/]+/)?perl5/.*\.p[lm]$}) {
+        push @{$self->perl_sources_in_lib}, $item;
+
+    }elsif ($item->name =~ m{^usr/lib/(?:[^/]+/)?perl5/.*\.(?:bs|so)$}) {
+        $self->has_perl_binaries(1);
+    }
+
+    # perl modules
+    if ($item->name =~ m{^usr/(?:share|lib)/perl/\S}) {
+
+        # check if it's the "perl" package itself
+        $self->pointed_hint('perl-module-in-core-directory', $item->pointer)
+          unless $self->processable->source_name eq 'perl';
+    }
+
+    # perl modules using old libraries
+    # we do the same check on perl scripts in checks/scripts
+    my $dep = $self->processable->relation('strong');
+    if (   $item->is_file
+        && $item->name =~ /\.pm$/
+        && !$dep->satisfies('libperl4-corelibs-perl | perl (<< 5.12.3-7)')) {
+
+        open(my $fd, '<', $item->unpacked_path)
+          or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+        my $position = 1;
+        while (my $line = <$fd>) {
+            if (
+                $line =~ m{ (?:do|require)\s+['"] # do/require
+
+                   # Huge list of perl4 modules...
+                   (abbrev|assert|bigfloat|bigint|bigrat
+                   |cacheout|complete|ctime|dotsh|exceptions
+                   |fastcwd|find|finddepth|flush|getcwd|getopt
+                   |getopts|hostname|importenv|look|newgetopt
+                   |open2|open3|pwd|shellwords|stat|syslog
+                   |tainted|termcap|timelocal|validate)
+                   # ... so they end with ".pl" rather than ".pm"
+                   \.pl['"]
+             }xsm
+            ) {
+                my $module = $1;
+
+                $self->pointed_hint('perl-module-uses-perl4-libs-without-dep',
+                    $item->pointer($position), "$module.pl");
+            }
+
+        } continue {
+            ++$position;
+        }
+
+        close $fd;
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    unless ($self->has_perl_binaries) {
+
+        $self->pointed_hint('package-installs-nonbinary-perl-in-usr-lib-perl5',
+            $_->pointer)
+          for @{$self->perl_sources_in_lib};
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Perl/Core/Provides.pm b/lib/Lintian/Check/Languages/Perl/Core/Provides.pm
new file mode 100644
index 0000000..b0a3923
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Perl/Core/Provides.pm
@@ -0,0 +1,83 @@
+# languages/perl/core/provides -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2021 Felix Lechner
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Perl::Core::Provides;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Dpkg::Version qw(version_check);
+
+use Lintian::Relation::Version qw(versions_compare);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub always {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    return
+      unless $fields->declares('Version');
+
+    my $version = $fields->unfolded_value('Version');
+
+    my $dversion = Dpkg::Version->new($version);
+    return
+      unless $dversion->is_valid;
+
+    my ($epoch, $upstream, $debian)
+      = ($dversion->epoch, $dversion->version, $dversion->revision);
+
+    my $PERL_CORE_PROVIDES= $self->data->load('fields/perl-provides', '\s+');
+
+    my $name = $fields->value('Package');
+
+    return
+      unless $PERL_CORE_PROVIDES->recognizes($name);
+
+    my $core_version = $PERL_CORE_PROVIDES->value($name);
+
+    my $no_revision = "$epoch:$upstream";
+    return
+      unless version_check($no_revision);
+
+    $self->hint('package-superseded-by-perl', "with $core_version")
+      if versions_compare($core_version, '>=', $no_revision);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Perl/Perl4/Prerequisites.pm b/lib/Lintian/Check/Languages/Perl/Perl4/Prerequisites.pm
new file mode 100644
index 0000000..fb5e9be
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Perl/Perl4/Prerequisites.pm
@@ -0,0 +1,124 @@
+# languages/perl/perl4/prerequisites -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Perl::Perl4::Prerequisites;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use File::Basename;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Relation;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# check for obsolete perl libraries
+const my $PERL4_PREREQUISITES =>
+  'libperl4-corelibs-perl:any | perl:any (<< 5.12.3-7)';
+
+has satisfies_perl4_prerequisites => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->processable->relation('strong')
+          ->satisfies($PERL4_PREREQUISITES);
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # Consider /usr/src/ scripts as "documentation"
+    # - packages containing /usr/src/ tend to be "-source" .debs
+    #   and usually come with overrides
+    # no checks necessary at all for scripts in /usr/share/doc/
+    # unless they are examples
+    return
+      if ($item->name =~ m{^usr/share/doc/} || $item->name =~ m{^usr/src/})
+      && $item->name !~ m{^usr/share/doc/[^/]+/examples/};
+
+    return
+      unless length $item->interpreter;
+
+    my $basename = basename($item->interpreter);
+    return
+      unless $basename eq 'perl';
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+        if (
+            $line =~m{ (?:do|require)\s+['"] # do/require
+
+                          # Huge list of perl4 modules...
+                          (abbrev|assert|bigfloat|bigint|bigrat
+                          |cacheout|complete|ctime|dotsh|exceptions
+                          |fastcwd|find|finddepth|flush|getcwd|getopt
+                          |getopts|hostname|importenv|look|newgetopt
+                          |open2|open3|pwd|shellwords|stat|syslog
+                          |tainted|termcap|timelocal|validate)
+                          # ... so they end with ".pl" rather than ".pm"
+                          \.pl['"]
+               }xsm
+        ) {
+
+            my $module = "$1.pl";
+
+            my $pointer = $item->pointer($position);
+
+            $self->pointed_hint(
+                'script-uses-perl4-libs-without-dep',$pointer,
+                "(does not satisfy $PERL4_PREREQUISITES)",$module
+            ) unless $self->satisfies_perl4_prerequisites;
+
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Perl/Perl5.pm b/lib/Lintian/Check/Languages/Perl/Perl5.pm
new file mode 100644
index 0000000..8b138ab
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Perl/Perl5.pm
@@ -0,0 +1,61 @@
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Perl::Perl5;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # Find mentioning of usr/lib/perl5 inside the packaging
+    $self->pointed_hint('mentions-deprecated-usr-lib-perl5-directory',
+        $item->pointer)
+      if $item->basename ne 'changelog'
+      && $item->name =~ m{^ debian/ }sx
+      && $item->name !~ m{^ debian/patches/ }sx
+      && $item->name !~ m{^ debian/ (?:.+\.)? install $}sx
+      && $item->bytes =~ m{^ [^#]* usr/lib/perl5 }msx;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Perl/Yapp.pm b/lib/Lintian/Check/Languages/Perl/Yapp.pm
new file mode 100644
index 0000000..adf3605
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Perl/Yapp.pm
@@ -0,0 +1,55 @@
+# languages/perl/yapp -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2019 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Perl::Yapp;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->name =~ /\.pm$/;
+
+    my $bytes = $item->bytes;
+    return
+      unless $bytes;
+
+    $self->pointed_hint('source-contains-prebuilt-yapp-parser', $item->pointer)
+      if $bytes
+      =~ /^#\s+This file was generated using Parse::Yapp version [\d.]+/m;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Php.pm b/lib/Lintian/Check/Languages/Php.pm
new file mode 100644
index 0000000..948a7a3
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Php.pm
@@ -0,0 +1,53 @@
+# languages/php -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Php;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # /etc/php/*/mods-available/*.ini
+    if (   $item->is_file
+        && $item->name =~ m{^etc/php/.*/mods-available/.+\.ini$}) {
+
+        $self->pointed_hint('obsolete-comments-style-in-php-ini',
+            $item->pointer)
+          if $item->decoded_utf8 =~ /^\s*#/m;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Php/Composer.pm b/lib/Lintian/Check/Languages/Php/Composer.pm
new file mode 100644
index 0000000..142c1e8
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Php/Composer.pm
@@ -0,0 +1,93 @@
+# languages/php/composer -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Php::Composer;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::Relation;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+    my $source_fields = $control->source_fields;
+
+    for my $field (
+        qw(Build-Depends Build-Depends-Indep
+        Build-Conflicts Build-Conflicts-Indep)
+    ) {
+        next
+          unless $source_fields->declares($field);
+
+        my $position = $source_fields->position($field);
+        my $pointer = $control->item->pointer($position);
+
+        my $raw = $source_fields->value($field);
+        my $relation = Lintian::Relation->new->load($raw);
+
+        my $condition = 'composer:any';
+
+        $self->pointed_hint('composer-prerequisite', $pointer, $field,
+            '(in source paragraph)')
+          if $relation->satisfies($condition);
+    }
+
+    for my $installable ($control->installables) {
+        my $installable_fields = $control->installable_fields($installable);
+
+        for my $field (
+            qw(Pre-Depends Depends Recommends Suggests Breaks
+            Conflicts Provides Replaces Enhances)
+        ) {
+            next
+              unless $installable_fields->declares($field);
+
+            my $position = $installable_fields->position($field);
+            my $pointer = $control->item->pointer($position);
+
+            my $relation
+              = $self->processable->binary_relation($installable, $field);
+
+            my $condition = 'composer:any';
+
+            $self->pointed_hint('composer-prerequisite', $pointer, $field,
+                "(in section for $installable)")
+              if $relation->satisfies($condition);
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Php/Embedded.pm b/lib/Lintian/Check/Languages/Php/Embedded.pm
new file mode 100644
index 0000000..2287f09
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Php/Embedded.pm
@@ -0,0 +1,92 @@
+# languages/php/embedded -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Php::Embedded;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+my $PHP_EXT = qr{(?i)\.(?:php|inc|dtd)$};
+my %PHP_FILES = (
+    'libphp-adodb'         => qr{(?i)/adodb\.inc\.php$},
+    'smarty3?'             => qr{(?i)/Smarty(?:_Compiler)?\.class\.php$},
+    'libphp-phpmailer'     => qr{(?i)/class\.phpmailer(\.(?:php|inc))+$},
+    'phpsysinfo'           =>
+qr{(?i)/phpsysinfo\.dtd|/class\.(?:Linux|(?:Open|Net|Free|)BSD)\.inc\.php$},
+    'php-openid'           => qr{/Auth/(?:OpenID|Yadis/Yadis)\.php$},
+    'libphp-snoopy'        => qr{(?i)/Snoopy\.class\.(?:php|inc)$},
+    'php-markdown'         => qr{(?i)/markdown\.php$},
+    'php-geshi'            => qr{(?i)/geshi\.php$},
+    'libphp-pclzip'        =>qr{(?i)/(?:class[.-])?pclzip\.(?:inc|lib)?\.php$},
+    'libphp-phplayersmenu' => qr{(?i)/.*layersmenu.*/(lib/)?PHPLIB\.php$},
+    'libphp-phpsniff'      => qr{(?i)/phpSniff\.(?:class|core)\.php$},
+    'libphp-jabber'        => qr{(?i)/(?:class\.)?jabber\.php$},
+    'libphp-simplepie'     =>
+      qr{(?i)/(?:class[\.-])?simplepie(?:\.(?:php|inc))+$},
+    'libphp-jpgraph'       => qr{(?i)/jpgraph\.php$},
+    'php-fpdf'             => qr{(?i)/fpdf\.php$},
+    'php-getid3'           => qr{(?i)/getid3\.(?:lib\.)?(?:\.(?:php|inc))+$},
+    'php-php-gettext'      => qr{(?i)/(?<!pomo/)streams\.php$},
+    'libphp-magpierss'     => qr{(?i)/rss_parse\.(?:php|inc)$},
+    'php-simpletest'       => qr{(?i)/unit_tester\.php$},
+    'libsparkline-php'     => qr{(?i)/Sparkline\.php$},
+    'libnusoap-php'        => qr{(?i)/(?:class\.)?nusoap\.(?:php|inc)$},
+    'php-htmlpurifier'     => qr{(?i)/HTMLPurifier\.php$},
+    # not yet available in unstable:,
+    # 'libphp-ixr'         => qr{(?i)/IXR_Library(?:\.inc|\.php)+$},
+    # 'libphp-kses'        => qr{(?i)/(?:class\.)?kses\.php$},
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # embedded PHP
+    for my $provider (keys %PHP_FILES) {
+
+        next
+          if $self->processable->name =~ /^$provider$/;
+
+        next
+          unless $item->name =~ /$PHP_FILES{$provider}/;
+
+        $self->pointed_hint('embedded-php-library', $item->pointer,
+            'please use',$provider);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Php/Pear.pm b/lib/Lintian/Check/Languages/Php/Pear.pm
new file mode 100644
index 0000000..b73b268
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Php/Pear.pm
@@ -0,0 +1,242 @@
+# langauges/php/pear -- lintian check script -*- perl -*-
+
+# Copyright (C) 2013 Mathieu Parent <math.parent@gmail.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Php::Pear;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(none);
+use Unicode::UTF8 qw(encode_utf8);
+
+const my $DOLLAR => q{$};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    # Don't check package if it doesn't contain a .php file
+    if (none { $_->basename =~ m/\.php$/i && !$_->is_dir }
+        @{$self->processable->patched->sorted_list}){
+        return;
+    }
+
+    my $build_depends = $self->processable->relation('Build-Depends');
+    my $package_type = 'unknown';
+
+    # PEAR or PECL package
+    my $package_xml = $self->processable->patched->lookup('package.xml');
+    my $package2_xml = $self->processable->patched->lookup('package2.xml');
+
+    my $debian_control = $self->processable->debian_control;
+
+    if (defined($package_xml) || defined($package2_xml)) {
+        # Checking source builddep
+        if (!$build_depends->satisfies('pkg-php-tools')) {
+            $self->hint('pear-package-without-pkg-php-tools-builddep');
+
+        } else {
+            # Checking first binary relations
+            my @binaries = $debian_control->installables;
+            my $binary = $binaries[0];
+
+            my $depends
+              = $self->processable->binary_relation($binary, 'Depends');
+            my $recommends
+              = $self->processable->binary_relation($binary, 'Recommends');
+            my $breaks= $self->processable->binary_relation($binary, 'Breaks');
+
+            $self->hint('pear-package-but-missing-dependency', 'Depends')
+              unless $depends->satisfies($DOLLAR . '{phppear:Debian-Depends}');
+
+            $self->hint('pear-package-but-missing-dependency','Recommends')
+              unless $recommends->satisfies(
+                $DOLLAR . '{phppear:Debian-Recommends}');
+
+            $self->hint('pear-package-but-missing-dependency', 'Breaks')
+              unless $breaks->satisfies($DOLLAR . '{phppear:Debian-Breaks}');
+
+            # checking description
+            my $description
+              = $debian_control->installable_fields($binary)
+              ->untrimmed_value('Description');
+
+            $self->hint(
+                'pear-package-not-using-substvar',
+                $DOLLAR . '{phppear:summary}'
+            )if $description !~ /\$\{phppear:summary\}/;
+
+            $self->hint(
+                'pear-package-not-using-substvar',
+                $DOLLAR . '{phppear:description}'
+            )if $description !~ /\$\{phppear:description\}/;
+
+            if (defined $package_xml && $package_xml->is_regular_file) {
+
+                # Wild guess package type as in
+                # PEAR_PackageFile_v2::getPackageType()
+                open(my $package_xml_fd, '<', $package_xml->unpacked_path)
+                  or die encode_utf8(
+                    'Cannot open ' . $package_xml->unpacked_path);
+
+                while (my $line = <$package_xml_fd>) {
+                    if (
+                        $line =~ m{\A \s* <
+                           (php|extsrc|extbin|zendextsrc|zendextbin)
+                           release \s* /? > }xsm
+                    ) {
+                        $package_type = $1;
+                        last;
+                    }
+                    if ($line =~ /^\s*<bundle\s*\/?>/){
+                        $package_type = 'bundle';
+                        last;
+                    }
+                }
+
+                close $package_xml_fd;
+
+                if ($package_type eq 'extsrc') { # PECL package
+                    if (!$build_depends->satisfies('php-dev')) {
+
+                        $self->pointed_hint(
+                            'pecl-package-requires-build-dependency',
+                            $package_xml->pointer,'php-dev');
+                    }
+
+                    if (!$build_depends->satisfies('dh-php')) {
+                        $self->pointed_hint(
+                            'pecl-package-requires-build-dependency',
+                            $package_xml->pointer,'dh-php');
+                    }
+                }
+            }
+        }
+    }
+
+    # PEAR channel
+    my $channel_xml = $self->processable->patched->lookup('channel.xml');
+    $self->pointed_hint('pear-channel-without-pkg-php-tools-builddep',
+        $channel_xml->pointer)
+      if defined $channel_xml
+      && !$build_depends->satisfies('pkg-php-tools');
+
+    # Composer package
+    my $composer_json = $self->processable->patched->lookup('composer.json');
+    $self->pointed_hint('composer-package-without-pkg-php-tools-builddep',
+        $composer_json->pointer)
+      if defined $composer_json
+      && !($build_depends->satisfies('pkg-php-tools')
+        || $build_depends->satisfies('dh-sequence-phpcomposer'))
+      && !defined $package_xml
+      && !defined $package2_xml;
+
+    # Check rules
+    if (
+        $build_depends->satisfies('pkg-php-tools')
+        && (   defined $package_xml
+            || defined $package2_xml
+            || defined $channel_xml
+            || defined $composer_json)
+    ) {
+        my $rules = $self->processable->patched->resolve_path('debian/rules');
+        if (defined $rules && $rules->is_open_ok) {
+
+            my $has_buildsystem_phppear = 0;
+            my $has_addon_phppear = 0;
+            my $has_addon_phpcomposer= 0;
+            my $has_addon_php = 0;
+
+            open(my $rules_fd, '<', $rules->unpacked_path)
+              or die encode_utf8('Cannot open ' . $rules->unpacked_path);
+
+            while (my $line = <$rules_fd>) {
+
+                while ($line =~ s/\\$// && defined(my $cont = <$rules_fd>)) {
+                    $line .= $cont;
+                }
+
+                next
+                  if $line =~ /^\s*\#/;
+
+                $has_buildsystem_phppear = 1
+                  if $line
+                  =~ /^\t\s*dh\s.*--buildsystem(?:=|\s+)(?:\S+,)*phppear(?:,\S+)*\s/;
+
+                $has_addon_phppear = 1
+                  if $line
+                  =~ /^\t\s*dh\s.*--with(?:=|\s+)(?:\S+,)*phppear(?:,\S+)*\s/;
+
+                $has_addon_phpcomposer = 1
+                  if $line
+                  =~ /^\t\s*dh\s.*--with(?:=|\s+)(?:\S+,)*phpcomposer(?:,\S+)*\s/;
+
+                $has_addon_php = 1
+                  if $line
+                  =~ /^\t\s*dh\s.*--with(?:=|\s+)(?:\S+,)*php(?:,\S+)*\s/;
+            }
+
+            close $rules_fd;
+
+            if (   defined $package_xml
+                || defined $package2_xml
+                || defined $channel_xml) {
+
+                $self->pointed_hint('missing-pkg-php-tools-buildsystem',
+                    $rules->pointer, 'phppear')
+                  unless $has_buildsystem_phppear;
+
+                $self->pointed_hint('missing-pkg-php-tools-addon',
+                    $rules->pointer, 'phppear')
+                  unless $has_addon_phppear;
+
+                $self->pointed_hint('missing-pkg-php-tools-addon',
+                    $rules->pointer, 'php')
+                  if $package_type eq 'extsrc'
+                  && !$has_addon_php;
+            }
+
+            if (   !defined $package_xml
+                && !defined $package2_xml
+                && defined $composer_json) {
+
+                $self->pointed_hint('missing-pkg-php-tools-addon',
+                    $rules->pointer, 'phpcomposer')
+                  unless $has_addon_phpcomposer;
+            }
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Php/Pear/Embedded.pm b/lib/Lintian/Check/Languages/Php/Pear/Embedded.pm
new file mode 100644
index 0000000..dfb1268
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Php/Pear/Embedded.pm
@@ -0,0 +1,92 @@
+# languages/php/pear/embedded -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Php::Pear::Embedded;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+my $PEAR_MAGIC = qr{pear[/.]};
+my $PEAR_EXT = qr{(?i)\.php$};
+my %PEAR_FILES = (
+    'php-auth'            => qr{/Auth} . $PEAR_EXT,
+    'php-auth-http'       => qr{/Auth/HTTP} . $PEAR_EXT,
+    'php-benchmark'       => qr{/Benchmark/(?:Timer|Profiler|Iterate)}
+      . $PEAR_EXT,
+    'php-http'            => qr{(?<!/Auth)/HTTP} . $PEAR_EXT,
+    'php-cache'           => qr{/Cache} . $PEAR_EXT,
+    'php-cache-lite'      => qr{/Cache/Lite} . $PEAR_EXT,
+    'php-compat'          => qr{/Compat} . $PEAR_EXT,
+    'php-config'          => qr{/Config} . $PEAR_EXT,
+    'php-crypt-cbc'       => qr{/CBC} . $PEAR_EXT,
+    'php-date'            => qr{/Date} . $PEAR_EXT,
+    'php-db'              => qr{(?<!/Container)/DB} . $PEAR_EXT,
+    'php-file'            => qr{(?<!/Container)/File} . $PEAR_EXT,
+    'php-log'             =>
+      qr{(?:/Log/(?:file|error_log|null|syslog|sql\w*)|/Log)} . $PEAR_EXT,
+    'php-mail'            => qr{/Mail} . $PEAR_EXT,
+    'php-mail-mime'       => qr{(?i)/mime(Part)?} . $PEAR_EXT,
+    'php-mail-mimedecode' => qr{/mimeDecode} . $PEAR_EXT,
+    'php-net-ftp'         => qr{/FTP} . $PEAR_EXT,
+    'php-net-imap'        => qr{(?<!/Container)/IMAP} . $PEAR_EXT,
+    'php-net-ldap'        => qr{(?<!/Container)/LDAP} . $PEAR_EXT,
+    'php-net-smtp'        => qr{/SMTP} . $PEAR_EXT,
+    'php-net-socket'      => qr{(?<!/FTP)/Socket} . $PEAR_EXT,
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # embedded PEAR
+    for my $provider (keys %PEAR_FILES) {
+
+        next
+          if $self->processable->name =~ /^$provider$/;
+
+        next
+          unless $item->name =~ /$PEAR_FILES{$provider}/;
+
+        next
+          unless length $item->bytes_match($PEAR_MAGIC);
+
+        $self->pointed_hint('embedded-pear-module', $item->pointer,
+            'please use',$provider);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Python.pm b/lib/Lintian/Check/Languages/Python.pm
new file mode 100644
index 0000000..089fce4
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Python.pm
@@ -0,0 +1,516 @@
+# languages/python -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2016 Chris Lamb
+# Copyright (C) 2020 Louis-Philippe Veronneau <pollo@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Python;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any none);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Relation;
+use Lintian::Relation::Version qw(versions_lte);
+
+const my $EMPTY => q{};
+const my $ARROW => q{ -> };
+const my $DOLLAR => q{$};
+
+const my $PYTHON3_MAJOR => 3;
+const my $PYTHON2_MIGRATION_MAJOR => 2;
+const my $PYTHON2_MIGRATION_MINOR => 6;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+my @FIELDS = qw(Depends Pre-Depends Recommends Suggests);
+my @IGNORE = qw(-dev$ -docs?$ -common$ -tools$);
+my @PYTHON2 = qw(python2:any python2.7:any python2-dev:any);
+my @PYTHON3 = qw(python3:any python3-dev:any);
+
+my %DJANGO_PACKAGES = (
+    '^python3-django-' => 'python3-django',
+    '^python2?-django-' => 'python-django',
+);
+
+my %REQUIRED_DEPENDS = (
+    'python2' => 'python2-minimal:any | python2:any',
+    'python3' => 'python3-minimal:any | python3:any',
+);
+
+my %MISMATCHED_SUBSTVARS = (
+    '^python3-.+' => $DOLLAR . '{python:Depends}',
+    '^python2?-.+' => $DOLLAR . '{python3:Depends}',
+);
+
+has ALLOWED_PYTHON_FILES => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->load('files/allowed-python-files');
+    }
+);
+has GENERIC_PYTHON_MODULES => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->load('files/generic-python-modules');
+    }
+);
+
+my @VERSION_FIELDS = qw(X-Python-Version XS-Python-Version X-Python3-Version);
+
+has correct_location => (is => 'rw', default => sub { {} });
+
+sub source {
+    my ($self) = @_;
+
+    my @installable_names = $self->processable->debian_control->installables;
+    for my $installable_name (@installable_names) {
+        # Python 2 modules
+        if ($installable_name =~ /^python2?-(.*)$/) {
+            my $suffix = $1;
+
+            next
+              if any { $installable_name =~ /$_/ } @IGNORE;
+
+            next
+              if any { $_ eq "python3-${suffix}" } @installable_names;
+
+            # Don't trigger if we ship any Python 3 module
+            next
+              if any {
+                $self->processable->binary_relation($_, 'all')
+                  ->satisfies($DOLLAR . '{python3:Depends}')
+              }@installable_names;
+
+            $self->hint('python-foo-but-no-python3-foo', $installable_name);
+        }
+    }
+
+    my $build_all = $self->processable->relation('Build-Depends-All');
+    $self->hint('build-depends-on-python-sphinx-only')
+      if $build_all->satisfies('python-sphinx')
+      && !$build_all->satisfies('python3-sphinx');
+
+    $self->hint(
+        'alternatively-build-depends-on-python-sphinx-and-python3-sphinx')
+      if $self->processable->fields->value('Build-Depends')
+      =~ /\bpython-sphinx\s+\|\s+python3-sphinx\b/;
+
+    my $debian_control = $self->processable->debian_control;
+
+    # Mismatched substvars
+    for my $regex (keys %MISMATCHED_SUBSTVARS) {
+        my $substvar = $MISMATCHED_SUBSTVARS{$regex};
+
+        for my $installable_name ($debian_control->installables) {
+
+            next
+              if any { $installable_name =~ /$_/ } @IGNORE;
+
+            next
+              if $installable_name !~ qr/$regex/;
+
+            $self->hint('mismatched-python-substvar', $installable_name,
+                $substvar)
+              if $self->processable->binary_relation($installable_name, 'all')
+              ->satisfies($substvar);
+        }
+    }
+
+    my $VERSIONS = $self->data->load('python/versions', qr/\s*=\s*/);
+
+    for my $field (@VERSION_FIELDS) {
+
+        next
+          unless $debian_control->source_fields->declares($field);
+
+        my $pyversion= $debian_control->source_fields->value($field);
+
+        my @valid = (
+            ['\d+\.\d+', '\d+\.\d+'],['\d+\.\d+'],
+            ['\>=\s*\d+\.\d+', '\<\<\s*\d+\.\d+'],['\>=\s*\d+\.\d+'],
+            ['current', '\>=\s*\d+\.\d+'],['current'],
+            ['all']
+        );
+
+        my @pyversion = split(/\s*,\s*/, $pyversion);
+
+        if ($pyversion =~ m/^current/) {
+            $self->hint('python-version-current-is-deprecated', $field);
+        }
+
+        if (@pyversion > 2) {
+            if (any { !/^\d+\.\d+$/ } @pyversion) {
+                $self->hint('malformed-python-version', $field, $pyversion);
+            }
+        } else {
+            my $okay = 0;
+            for my $rule (@valid) {
+                if (
+                    $pyversion[0] =~ /^$rule->[0]$/
+                    && (
+                        (
+                            $pyversion[1]
+                            && $rule->[1]
+                            && $pyversion[1] =~ /^$rule->[1]$/
+                        )
+                        || (!$pyversion[1] && !$rule->[1])
+                    )
+                ) {
+                    $okay = 1;
+                    last;
+                }
+            }
+            $self->hint('malformed-python-version', $field, $pyversion)
+              unless $okay;
+        }
+
+        if ($pyversion =~ /\b(([23])\.\d+)$/) {
+            my ($v, $major) = ($1, $2);
+            my $old = $VERSIONS->value("old-python$major");
+            my $ancient = $VERSIONS->value("ancient-python$major");
+
+            if (versions_lte($v, $ancient)) {
+                $self->hint('ancient-python-version-field', $field, $v);
+            } elsif (versions_lte($v, $old)) {
+                $self->hint('old-python-version-field', $field, $v);
+            }
+        }
+    }
+
+    $self->hint('source-package-encodes-python-version')
+      if $self->processable->name =~ m/^python\d-/
+      && $self->processable->name ne 'python3-defaults';
+
+    my $build_depends = Lintian::Relation->new;
+    $build_depends->load_norestriction(
+        $self->processable->fields->value('Build-Depends'));
+
+    my $pyproject= $self->processable->patched->resolve_path('pyproject.toml');
+    if (defined $pyproject && $pyproject->is_open_ok) {
+
+        my %PYPROJECT_PREREQUISITES = (
+            'poetry.core.masonry.api' => 'python3-poetry-core:any',
+            'flit_core.buildapi' => 'flit:any',
+            'setuptools.build_meta' => 'python3-setuptools:any',
+            'pdm.pep517.api' => 'python3-pdm-pep517:any',
+            'hatchling.build' => 'python3-hatchling:any',
+            'mesonpy' => 'python3-mesonpy:any',
+            'sipbuild.api' => 'python3-sipbuild:any'
+        );
+
+        open(my $fd, '<', $pyproject->unpacked_path)
+          or die encode_utf8('Cannot open ' . $pyproject->unpacked_path);
+
+        my $position = 1;
+        while (my $line = <$fd>) {
+
+            my $pointer = $pyproject->pointer($position);
+
+           # In theory, TOML only uses double quotes. In practice, that's not
+           # true and only matching for double quotes introduce false negatives
+            if ($line =~ m{^ \s* build-backend \s* = \s* "([^"]+)" }x
+                ||  $line =~ m{^ \s* build-backend \s* = \s* '([^"]+)' }x) {
+
+                my $backend = $1;
+
+                $self->pointed_hint('uses-poetry-cli', $pointer)
+                  if $backend eq 'poetry.core.masonry.api'
+                  && $build_depends->satisfies('python3-poetry:any')
+                  && !$build_depends->satisfies('python3-poetry-core:any');
+
+                $self->pointed_hint('uses-pdm-cli', $pointer)
+                  if $backend eq 'pdm.pep517.api'
+                  && $build_depends->satisfies('python3-pdm:any')
+                  && !$build_depends->satisfies('python3-pdm-pep517:any');
+
+                if (exists $PYPROJECT_PREREQUISITES{$backend}) {
+
+                    my $prerequisites = $PYPROJECT_PREREQUISITES{$backend}
+                      . ', pybuild-plugin-pyproject:any';
+
+                    $self->pointed_hint(
+                        'missing-prerequisite-for-pyproject-backend',
+                        $pointer, $backend,"(does not satisfy $prerequisites)")
+                      if !$build_all->satisfies($prerequisites);
+                }
+            }
+
+        } continue {
+            ++$position;
+        }
+
+        close $fd;
+    }
+
+    return;
+}
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # .pyc/.pyo (compiled Python files)
+    #  skip any file installed inside a __pycache__ directory
+    #  - we have a separate check for that directory.
+    $self->pointed_hint('package-installs-python-bytecode', $item->pointer)
+      if $item->name =~ /\.py[co]$/
+      && $item->name !~ m{/__pycache__/};
+
+    # __pycache__ (directory for pyc/pyo files)
+    $self->pointed_hint('package-installs-python-pycache-dir', $item->pointer)
+      if $item->is_dir
+      && $item->name =~ m{/__pycache__/};
+
+    if (   $item->is_file
+        && $item->name
+        =~ m{^usr/lib/debug/usr/lib/pyshared/(python\d?(?:\.\d+))/(.+)$}) {
+
+        my $correct = "usr/lib/debug/usr/lib/pymodules/$1/$2";
+        $self->pointed_hint('python-debug-in-wrong-location',
+            $item->pointer, "better: $correct");
+    }
+
+    # .egg (Python egg files)
+    $self->pointed_hint('package-installs-python-egg', $item->pointer)
+      if $item->name =~ /\.egg$/
+      && ( $item->name =~ m{^usr/lib/python\d+(?:\.\d+/)}
+        || $item->name =~ m{^usr/lib/pyshared}
+        || $item->name =~ m{^usr/share/});
+
+    # /usr/lib/site-python
+    $self->pointed_hint('file-in-usr-lib-site-python', $item->pointer)
+      if $item->name =~ m{^usr/lib/site-python/\S};
+
+    # pythonX.Y extensions
+    if (   $item->name =~ m{^usr/lib/python\d\.\d/\S}
+        && $item->name !~ m{^usr/lib/python\d\.\d/(?:site|dist)-packages/}){
+
+        $self->pointed_hint('third-party-package-in-python-dir',$item->pointer)
+          unless $self->processable->source_name =~ m/^python(?:\d\.\d)?$/
+          || $self->processable->source_name =~ m{\A python\d?-
+                               (?:stdlib-extensions|profiler|old-doctools) \Z}xsm;
+    }
+
+    # ---------------- Python file locations
+    #  - The Python people kindly provided the following table.
+    # good:
+    # /usr/lib/python2.5/site-packages/
+    # /usr/lib/python2.6/dist-packages/
+    # /usr/lib/python2.7/dist-packages/
+    # /usr/lib/python3/dist-packages/
+    #
+    # bad:
+    # /usr/lib/python2.5/dist-packages/
+    # /usr/lib/python2.6/site-packages/
+    # /usr/lib/python2.7/site-packages/
+    # /usr/lib/python3.*/*-packages/
+    if (
+        $item->name =~ m{\A
+                   (usr/lib/debug/)?
+                   usr/lib/python(\d+(?:\.\d+)?)/
+                   ((?:site|dist)-packages)/(.+)
+                   \Z}xsm
+    ){
+        my ($debug, $pyver, $actual_package_dir, $relative) = ($1, $2, $3, $4);
+        $debug //= $EMPTY;
+
+        my ($pmaj, $pmin) = split(m{\.}, $pyver, 2);
+        $pmin //= 0;
+
+        next
+          if $pmaj < $PYTHON2_MIGRATION_MAJOR;
+
+        my ($module_name) = ($relative =~ m{^([^/]+)});
+
+        my $actual_python_libpath = "usr/lib/python$pyver/";
+        my $specified_python_libpath = "usr/lib/python$pmaj/";
+
+        # for python 2.X, folder was python2.X and not python2
+        $specified_python_libpath = $actual_python_libpath
+          if $pmaj < $PYTHON3_MAJOR;
+
+        my $specified_package_dir = 'dist-packages';
+
+        # python 2.4 and 2.5
+        $specified_package_dir = 'site-packages'
+          if $pmaj == $PYTHON2_MIGRATION_MAJOR
+          && $pmin < $PYTHON2_MIGRATION_MINOR;
+
+        my $actual_module_path
+          = $debug. $actual_python_libpath. "$actual_package_dir/$module_name";
+        my $specified_module_path
+          = $debug
+          . $specified_python_libpath
+          . "$specified_package_dir/$module_name";
+
+        $self->correct_location->{$actual_module_path} = $specified_module_path
+          unless $actual_module_path eq $specified_module_path;
+
+        for my $regex ($self->GENERIC_PYTHON_MODULES->all) {
+            $self->pointed_hint('python-module-has-overly-generic-name',
+                $item->pointer, "($1)")
+              if $relative =~ m{^($regex)(?:\.py|/__init__\.py)$}i;
+        }
+
+        $self->pointed_hint('unknown-file-in-python-module-directory',
+            $item->pointer)
+          if $item->is_file
+          && $relative eq $item->basename  # "top-level"
+          &&!$self->ALLOWED_PYTHON_FILES->matches_any($item->basename, 'i');
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    $self->hint(
+        'python-module-in-wrong-location',
+        $_ . $ARROW . $self->correct_location->{$_}
+    )for keys %{$self->correct_location};
+
+    my $deps
+      = $self->processable->relation('all')
+      ->logical_and($self->processable->relation('Provides'),
+        $self->processable->name);
+
+    my @entries
+      = $self->processable->changelog
+      ? @{$self->processable->changelog->entries}
+      : ();
+
+    # Check for missing dependencies
+    if ($self->processable->name !~ /-dbg$/) {
+        for my $item (@{$self->processable->installed->sorted_list}) {
+
+            if (   $item->is_file
+                && $item->name
+                =~ m{^usr/lib/(?<version>python[23])[\d.]*/(?:site|dist)-packages}
+                && !$deps->satisfies($REQUIRED_DEPENDS{$+{version}})) {
+
+                $self->hint('python-package-missing-depends-on-python');
+
+                last;
+            }
+        }
+    }
+
+    # Check for duplicate dependencies
+    for my $field (@FIELDS) {
+        my $dep = $self->processable->relation($field);
+      FIELD: for my $py2 (@PYTHON2) {
+            for my $py3 (@PYTHON3) {
+
+                if ($dep->satisfies($py2) && $dep->satisfies($py3)) {
+                    $self->hint('depends-on-python2-and-python3',
+                        $field, "(satisfies $py2, $py3)");
+                    last FIELD;
+                }
+            }
+        }
+    }
+
+    my $pkg = $self->processable->name;
+
+    # Python 2 modules
+    $self->hint('new-package-should-not-package-python2-module',
+        $self->processable->name)
+      if $self->processable->name =~ / ^ python2? - /msx
+      && (none { $pkg =~ m{ $_ }x } @IGNORE)
+      && @entries == 1
+      && $entries[0]->Changes
+      !~ / \b python [ ]? 2 (?:[.]x)? [ ] (?:variant|version) \b /imsx
+      && $entries[0]->Changes !~ / \Q$pkg\E /msx;
+
+    # Python applications
+    if ($self->processable->name !~ /^python[23]?-/
+        && (none { $_ eq $self->processable->name } @PYTHON2)) {
+        for my $field (@FIELDS) {
+            for my $dep (@PYTHON2) {
+
+                $self->hint(
+                    'dependency-on-python-version-marked-for-end-of-life',
+                    $field, "(satisfies $dep)")
+                  if $self->processable->relation($field)->satisfies($dep);
+            }
+        }
+    }
+
+    # Django modules
+    for my $regex (keys %DJANGO_PACKAGES) {
+        my $basepkg = $DJANGO_PACKAGES{$regex};
+
+        next
+          if $self->processable->name !~ /$regex/;
+
+        next
+          if any { $self->processable->name =~ /$_/ } @IGNORE;
+
+        $self->hint('django-package-does-not-depend-on-django', $basepkg)
+          unless $self->processable->relation('strong')->satisfies($basepkg);
+    }
+
+    if (
+        $self->processable->name =~ /^python([23]?)-/
+        && (none { $self->processable->name =~ /$_/ } @IGNORE)
+    ) {
+        my $version = $1 || '2'; # Assume python-foo is a Python 2.x package
+        my @prefixes = ($version eq '2') ? 'python3' : qw(python python2);
+
+        for my $field (@FIELDS) {
+            for my $prefix (@prefixes) {
+
+                my $visit = sub {
+                    my $rel = $_;
+                    return if any { $rel =~ /$_/ } @IGNORE;
+                    $self->hint(
+'python-package-depends-on-package-from-other-python-variant',
+                        "$field: $rel"
+                    ) if /^$prefix-/;
+                };
+
+                $self->processable->relation($field)
+                  ->visit($visit, Lintian::Relation::VISIT_PRED_NAME);
+            }
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Python/BogusPrerequisites.pm b/lib/Lintian/Check/Languages/Python/BogusPrerequisites.pm
new file mode 100644
index 0000000..fe2df7f
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Python/BogusPrerequisites.pm
@@ -0,0 +1,88 @@
+# languages/python/bogus-prerequisites -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Python::BogusPrerequisites;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub installable {
+    my ($self) = @_;
+
+    $self->what_is_python($self->processable->source_name,
+        qw{Depends Pre-Depends Recommends});
+
+    return;
+}
+
+sub source {
+    my ($self) = @_;
+
+    $self->what_is_python($self->processable->name,
+        qw{Build-Depends Build-Depends-Indep Build-Depends-Arch});
+
+    return;
+}
+
+sub what_is_python {
+    my ($self, $source, @fields) = @_;
+
+    # see Bug#973011
+    my @WHAT_IS_PYTHON = qw(
+      python-is-python2:any
+      python-dev-is-python2:any
+      python-is-python3:any
+      python-dev-is-python3:any
+    );
+
+    my %BOGUS_PREREQUISITES;
+
+    unless ($source eq 'what-is-python') {
+
+        for my $unwanted (@WHAT_IS_PYTHON) {
+
+            $BOGUS_PREREQUISITES{$unwanted}
+              = [grep {$self->processable->relation($_)->satisfies($unwanted)}
+                  @fields];
+        }
+    }
+
+    for my $unwanted (keys %BOGUS_PREREQUISITES) {
+
+        $self->hint('bogus-python-prerequisite', $_, "(satisfies $unwanted)")
+          for @{$BOGUS_PREREQUISITES{$unwanted}};
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Python/DistOverrides.pm b/lib/Lintian/Check/Languages/Python/DistOverrides.pm
new file mode 100644
index 0000000..2dadeb6
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Python/DistOverrides.pm
@@ -0,0 +1,80 @@
+# languages/python/dist-overrides -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Python::DistOverrides;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(uniq);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SPACE => q{ };
+
+sub source {
+    my ($self) = @_;
+
+    my $override_file
+      = $self->processable->patched->resolve_path('debian/py3dist-overrides');
+    return
+      unless defined $override_file;
+
+    my $contents = $override_file->decoded_utf8;
+    return
+      unless length $contents;
+
+    # strip comments
+    $contents =~ s/^\s*\#.*$//mg;
+
+    # strip empty lines
+    $contents =~ s/^\s*$//mg;
+
+    # trim leading spaces
+    $contents =~ s/^\s*//mg;
+
+    my @lines = split(/\n/, $contents);
+
+    # get first component from each line
+    my @identifiers
+      = grep { defined } map { (split($SPACE, $_, 2))[0] } @lines;
+
+    my %count;
+    $count{$_}++ for @identifiers;
+
+    my @duplicates = grep { $count{$_} > 1 } uniq @identifiers;
+
+    $self->hint('duplicate-p3dist-override', $_) for @duplicates;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Python/Distutils.pm b/lib/Lintian/Check/Languages/Python/Distutils.pm
new file mode 100644
index 0000000..cbc30ce
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Python/Distutils.pm
@@ -0,0 +1,77 @@
+# languages/python/distutils -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2022 Louis-Philippe Véronneau <pollo@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Python::Distutils;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+my $PYTHON3_DEPEND
+  = 'python3:any | python3-dev:any | python3-all:any | python3-all-dev:any';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    my $build_all = $self->processable->relation('Build-Depends-All');
+
+    # Skip if the package doesn't depend on python
+    return
+      unless $build_all->satisfies($PYTHON3_DEPEND);
+
+    # Skip if it's not a python file
+    return
+      unless $item->name =~ /\.py$/;
+
+    # Skip if we can't open the file
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        my $pointer = $item->pointer($position);
+
+        $self->pointed_hint('uses-python-distutils', $pointer)
+          if $line =~ m{^from distutils} || $line =~ m{^import distutils};
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Python/Feedparser.pm b/lib/Lintian/Check/Languages/Python/Feedparser.pm
new file mode 100644
index 0000000..da716e7
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Python/Feedparser.pm
@@ -0,0 +1,54 @@
+# languages/python/feedparser -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Python::Feedparser;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # embedded Feedparser library
+    $self->pointed_hint('embedded-feedparser-library', $item->pointer)
+      if $item->name =~ m{ / feedparser[.]py $}x
+      && $item->bytes =~ /Universal feed parser/
+      && $self->processable->source_name ne 'feedparser';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Python/Homepage.pm b/lib/Lintian/Check/Languages/Python/Homepage.pm
new file mode 100644
index 0000000..18a0470
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Python/Homepage.pm
@@ -0,0 +1,59 @@
+# languages/python/homepage -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2021 Felix Lechner
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Python::Homepage;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+    if ($fields->declares('Homepage')) {
+
+        my $homepage = $fields->value('Homepage');
+
+        # see Bug#981932
+        $self->hint('pypi-homepage', $homepage)
+          if $homepage
+          =~ m{^http s? :// (?:www [.])? pypi (:?[.] python)? [.] org/}isx;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Python/Obsolete.pm b/lib/Lintian/Check/Languages/Python/Obsolete.pm
new file mode 100644
index 0000000..e810faa
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Python/Obsolete.pm
@@ -0,0 +1,63 @@
+# languages/python/obsolete -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Python::Obsolete;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $pycompat= $self->processable->patched->resolve_path('debian/pycompat');
+
+    $self->pointed_hint('debian-pycompat-is-obsolete', $pycompat->pointer)
+      if defined $pycompat
+      && $pycompat->is_file;
+
+    my $pyversions
+      = $self->processable->patched->resolve_path('debian/pyversions');
+
+    $self->pointed_hint('debian-pyversions-is-obsolete', $pyversions->pointer)
+      if defined $pyversions
+      && $pyversions->is_file;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Python/Scripts.pm b/lib/Lintian/Check/Languages/Python/Scripts.pm
new file mode 100644
index 0000000..988b915
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Python/Scripts.pm
@@ -0,0 +1,54 @@
+# languages/python/scripts -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2016 Chris Lamb
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Python::Scripts;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->name =~ m{(?:usr/)?bin/[^/]+};
+
+    return
+      unless $item->is_script;
+
+    $self->pointed_hint('script-uses-unversioned-python-in-shebang',
+        $item->pointer)
+      if $item->interpreter =~ m{^(?:/usr/bin/)?python$};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/R.pm b/lib/Lintian/Check/Languages/R.pm
new file mode 100644
index 0000000..daa8462
--- /dev/null
+++ b/lib/Lintian/Check/Languages/R.pm
@@ -0,0 +1,74 @@
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 1999 Joey Hess
+# Copyright (C) 2000 Sean 'Shaleh' Perry
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2007 Russ Allbery
+# Copyright (C) 2013-2018 Bastien ROUCARIES
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::R;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $RDATA_MAGIC_LENGTH => 4;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # Ensure we have a README.source for R data files
+    if (   $item->basename =~ /\.(?:rda|Rda|rdata|Rdata|RData)$/
+        && $item->is_open_ok
+        && $item->file_type =~ /gzip compressed data/
+        && !$self->processable->patched->resolve_path('debian/README.source')){
+
+        open(my $fd, '<:gzip', $item->unpacked_path)
+          or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+        read($fd, my $magic, $RDATA_MAGIC_LENGTH)
+          or die encode_utf8('Cannot read from ' . $item->unpacked_path);
+
+        close($fd);
+
+        $self->pointed_hint('r-data-without-readme-source', $item->pointer)
+          if $magic eq 'RDX2';
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/R/Architecture.pm b/lib/Lintian/Check/Languages/R/Architecture.pm
new file mode 100644
index 0000000..3ee0bd2
--- /dev/null
+++ b/lib/Lintian/Check/Languages/R/Architecture.pm
@@ -0,0 +1,69 @@
+# languages/r/architecture -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2021 Felix Lechner
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::R::Architecture;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has have_r_files => (is => 'rw', default => 0);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      if $item->is_dir;
+
+    $self->have_r_files(1)
+      if $item->name =~ m{^usr/lib/R/.*/DESCRIPTION$}
+      && $item->decoded_utf8 =~ /^NeedsCompilation: no/m;
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    $self->hint('r-package-not-arch-all')
+      if $self->processable->name =~ /^r-(?:cran|bioc|other)-/
+      && $self->have_r_files
+      && $self->processable->fields->value('Architecture') ne 'all';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/R/SiteLibrary.pm b/lib/Lintian/Check/Languages/R/SiteLibrary.pm
new file mode 100644
index 0000000..1ac6ac9
--- /dev/null
+++ b/lib/Lintian/Check/Languages/R/SiteLibrary.pm
@@ -0,0 +1,71 @@
+# languages/r/site-library -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Dylan Aissi
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::R::SiteLibrary;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::Relation;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has r_site_libraries => (is => 'rw', default => sub { [] });
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # R site libraries
+    if ($item->name =~ m{^usr/lib/R/site-library/(.*)/DESCRIPTION$}) {
+        push(@{$self->r_site_libraries}, $1);
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    $self->hint('ships-r-site-library', $_) for @{$self->r_site_libraries};
+
+    return
+      unless @{$self->r_site_libraries};
+
+    my $depends = $self->processable->relation('strong');
+
+    # no version allowed for virtual package; no alternatives
+    $self->hint('requires-r-api')
+      unless $depends->matches(qr/^r-api-[\w\d+-.]+$/,
+        Lintian::Relation::VISIT_OR_CLAUSE_FULL);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Ruby.pm b/lib/Lintian/Check/Languages/Ruby.pm
new file mode 100644
index 0000000..563f740
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Ruby.pm
@@ -0,0 +1,72 @@
+# languages/ruby -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2021 Felix Lechner
+#
+# Parts of the code were taken from the old check script, which
+# was Copyright (C) 1998 Richard Braakman (also licensed under the
+# GPL 2 or higher)
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Ruby;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+    if ($fields->declares('Homepage')) {
+
+        my $homepage = $fields->value('Homepage');
+
+        # rubygems itself is okay; see Bug#981935
+        $self->hint('rubygem-homepage', $homepage)
+          if $homepage
+          =~ m{^http s? :// (?:www [.])? rubygems [.] org/gems/}isx;
+    }
+
+    return;
+}
+
+sub binary {
+    my ($self) = @_;
+
+    my @prerequisites
+      = $self->processable->fields->trimmed_list('Depends', qr/,/);
+
+    my @ruby_interpreter = grep { / \b ruby-interpreter \b /x } @prerequisites;
+
+    $self->hint('ruby-interpreter-is-deprecated', $_)for @ruby_interpreter;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Languages/Rust.pm b/lib/Lintian/Check/Languages/Rust.pm
new file mode 100644
index 0000000..140134f
--- /dev/null
+++ b/lib/Lintian/Check/Languages/Rust.pm
@@ -0,0 +1,69 @@
+# languages/rust -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Sylvestre Ledru
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Languages::Rust;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $debian_control = $self->processable->debian_control;
+    for my $installable ($debian_control->installables) {
+
+        my $fields = $debian_control->installable_fields($installable);
+        my $extended = $fields->text('Description');
+
+        # drop synopsis
+        $extended =~ s/^ [^\n]* \n //sx;
+
+        $self->hint('rust-boilerplate', $installable)
+          if $extended
+          =~ /^ \QThis package contains the following binaries built from the Rust crate\E /isx;
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    $self->hint('empty-rust-library-declares-provides')
+      if $self->processable->name =~ /^librust-/
+      && $self->processable->not_just_docs
+      && length $self->processable->fields->value('Provides');
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Libraries/DebugSymbols.pm b/lib/Lintian/Check/Libraries/DebugSymbols.pm
new file mode 100644
index 0000000..4f04e6f
--- /dev/null
+++ b/lib/Lintian/Check/Libraries/DebugSymbols.pm
@@ -0,0 +1,59 @@
+# libraries/debug-symbols -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Libraries::DebugSymbols;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /^ [^,]* \b ELF \b /x;
+
+    # stripped but a debug or profiling library?
+    $self->pointed_hint('stripped-library', $item->pointer)
+      if $item->file_type !~ m{\bnot stripped\b}
+      && $item->name =~ m{^ (?:usr/)? lib/ (?: debug | profile ) / }x
+      && $item->size;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Libraries/Embedded.pm b/lib/Lintian/Check/Libraries/Embedded.pm
new file mode 100644
index 0000000..502af47
--- /dev/null
+++ b/lib/Lintian/Check/Libraries/Embedded.pm
@@ -0,0 +1,124 @@
+# libraries/embedded -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Libraries::Embedded;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::Compare;
+use Unicode::UTF8 qw(encode_utf8);
+
+const my $SPACE => q{ };
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has EMBEDDED_LIBRARIES => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %embedded_libraries;
+
+        my $data
+          = $self->data->load('binaries/embedded-libs',qr{ \s*+ [|][|] }x);
+
+        for my $label ($data->all) {
+
+            my $details = $data->value($label);
+
+            my ($pairs, $pattern) = split(m{ [|][|] }x, $details, 2);
+
+            my %result;
+            for my $kvpair (split($SPACE, $pairs)) {
+
+                my ($key, $value) = split(/=/, $kvpair, 2);
+                $result{$key} = $value;
+            }
+
+            my $lc= List::Compare->new([keys %result],
+                [qw{libname source source-regex}]);
+            my @unknown = $lc->get_Lonly;
+
+            die encode_utf8(
+"Unknown options @unknown for $label (in binaries/embedded-libs)"
+            )if @unknown;
+
+            die encode_utf8(
+"Both source and source-regex used for $label (in binaries/embedded-libs)"
+            )if length $result{source} && length $result{'source-regex'};
+
+            $result{match} = qr/$pattern/;
+
+            $result{libname} //= $label;
+            $result{source} //= $label;
+
+            $embedded_libraries{$label} = \%result;
+        }
+
+        return \%embedded_libraries;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /^ [^,]* \b ELF \b /x;
+
+    for my $embedded_name (keys %{$self->EMBEDDED_LIBRARIES}) {
+
+        my $library_data = $self->EMBEDDED_LIBRARIES->{$embedded_name};
+
+        next
+          if length $library_data->{'source-regex'}
+          && $self->processable->source_name=~ $library_data->{'source-regex'};
+
+        next
+          if length $library_data->{source}
+          && $self->processable->source_name eq $library_data->{source};
+
+        $self->pointed_hint('embedded-library', $item->pointer,
+            $library_data->{libname})
+          if $item->strings =~ $library_data->{match};
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Libraries/Shared/Exit.pm b/lib/Lintian/Check/Libraries/Shared/Exit.pm
new file mode 100644
index 0000000..5788808
--- /dev/null
+++ b/lib/Lintian/Check/Libraries/Shared/Exit.pm
@@ -0,0 +1,72 @@
+# libraries/shared/exit -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2018-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Libraries::Shared::Exit;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(any none);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# not presently used
+#my $UNKNOWN_SHARED_LIBRARY_EXCEPTIONS
+#  = $self->data->load('shared-libs/unknown-shared-library-exceptions');
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # shared library
+    return
+      unless @{$item->elf->{SONAME} // [] };
+
+    my @symbols = grep { $_->section eq '.text' || $_->section eq 'UND' }
+      @{$item->elf->{SYMBOLS} // []};
+
+    my @symbol_names = map { $_->name } @symbols;
+
+    # If it has an INTERP section it might be an application with
+    # a SONAME (hi openjdk-6, see #614305).  Also see the comment
+    # for "shared-library-is-executable" below.
+    $self->pointed_hint('exit-in-shared-library', $item->pointer)
+      if (any { m/^_?exit$/ } @symbol_names)
+      && (none { $_ eq 'fork' } @symbol_names)
+      && !length $item->elf->{INTERP};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Libraries/Shared/FilePermissions.pm b/lib/Lintian/Check/Libraries/Shared/FilePermissions.pm
new file mode 100644
index 0000000..663205e
--- /dev/null
+++ b/lib/Lintian/Check/Libraries/Shared/FilePermissions.pm
@@ -0,0 +1,72 @@
+# libraries/shared/file-permissions -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2018-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Libraries::Shared::FilePermissions;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $WIDELY_READABLE => oct(644);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # shared library
+    return
+      unless @{$item->elf->{SONAME} // [] };
+
+    # Yes.  But if the library has an INTERP section, it's
+    # designed to do something useful when executed, so don't
+    # report an error.  Also give ld.so a pass, since it's
+    # special.
+    $self->pointed_hint('shared-library-is-executable',
+        $item->pointer, $item->octal_permissions)
+      if $item->is_executable
+      && !$item->elf->{INTERP}
+      && $item->name !~ m{^lib.*/ld-[\d.]+\.so$};
+
+    $self->pointed_hint('odd-permissions-on-shared-library',
+        $item->pointer, $item->octal_permissions)
+      if !$item->is_executable
+      && $item->operm != $WIDELY_READABLE;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Libraries/Shared/Links.pm b/lib/Lintian/Check/Libraries/Shared/Links.pm
new file mode 100644
index 0000000..e25d3fd
--- /dev/null
+++ b/lib/Lintian/Check/Libraries/Shared/Links.pm
@@ -0,0 +1,167 @@
+# libraries/shared/links -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2018-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Libraries::Shared::Links;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(none);
+
+const my $ARROW => q{->};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has development_packages => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my @development_packages;
+
+        for my $installable ($self->group->get_installables) {
+
+            push(@development_packages, $installable)
+              if $installable->name =~ /-dev$/
+              && $installable->relation('strong')
+              ->satisfies($self->processable->name);
+        }
+
+        return \@development_packages;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # shared library
+    return
+      unless @{$item->elf->{SONAME} // [] };
+
+    my $soname = $item->elf->{SONAME}[0];
+
+    my @ldconfig_folders = @{$self->data->architectures->ldconfig_folders};
+    return
+      if none { $item->dirname eq $_ } @ldconfig_folders;
+
+    my $installed = $self->processable->installed;
+
+    my $versioned_name = $item->dirname . $soname;
+    my $versioned_item = $installed->lookup($versioned_name);
+
+    my $unversioned_name = $versioned_name;
+    # libtool "-release" variant
+    $unversioned_name =~ s/-[\d\.]+\.so$/.so/;
+    # determine shlib link name (w/o version)
+    $unversioned_name =~ s/\.so.+$/.so/;
+
+    $self->pointed_hint('lacks-versioned-link-to-shared-library',
+        $item->pointer, $versioned_name)
+      unless defined $versioned_item;
+
+    $self->pointed_hint(
+        'ldconfig-symlink-referencing-wrong-file',
+        $versioned_item->pointer,'should point to',
+        $versioned_item->link,'instead of',$item->basename
+      )
+      if $versioned_name ne $item->name
+      && defined $versioned_item
+      && $versioned_item->is_symlink
+      && $versioned_item->link ne $item->basename;
+
+    $self->pointed_hint(
+        'ldconfig-symlink-is-not-a-symlink',
+        $versioned_item->pointer,'should point to',
+        $item->name
+      )
+      if $versioned_name ne $item->name
+      && defined $versioned_item
+      && !$versioned_item->is_symlink;
+
+    # shlib symlink may not exist.
+    # if shlib doesn't _have_ a version, then $unversioned_name and
+    # $item->name will be equal, and it's not a development link,
+    # so don't complain.
+    $self->pointed_hint(
+        'link-to-shared-library-in-wrong-package',
+        $installed->lookup($unversioned_name)->pointer,
+        $item->name
+      )
+      if $unversioned_name ne $item->name
+      && defined $installed->lookup($unversioned_name);
+
+    # If the shared library is in /lib, we have to look for
+    # the dev symlink in /usr/lib
+    $unversioned_name = "usr/$unversioned_name"
+      unless $item->name =~ m{^usr/};
+
+    my @dev_links;
+    for my $dev_installable (@{$self->development_packages}) {
+        for my $dev_item (@{$dev_installable->installed->sorted_list}) {
+
+            next
+              unless $dev_item->is_symlink;
+
+            next
+              unless $dev_item->name =~ m{^ usr/lib/ }x;
+
+            # try absolute first
+            my $resolved = $installed->resolve_path($dev_item->link);
+
+            # otherwise relative
+            $resolved
+              = $installed->resolve_path($dev_item->dirname . $dev_item->link)
+              unless defined $resolved;
+
+            next
+              unless defined $resolved;
+
+            push(@dev_links, $dev_item)
+              if $resolved->name eq $item->name;
+        }
+    }
+
+    # found -dev package; library needs a symlink
+    $self->pointed_hint('lacks-unversioned-link-to-shared-library',
+        $item->pointer, "example: $unversioned_name")
+      if @{$self->development_packages}
+      && (none { $_->name =~ m{ [.]so $}x } @dev_links);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Libraries/Shared/MultiArch.pm b/lib/Lintian/Check/Libraries/Shared/MultiArch.pm
new file mode 100644
index 0000000..52c1bc5
--- /dev/null
+++ b/lib/Lintian/Check/Libraries/Shared/MultiArch.pm
@@ -0,0 +1,79 @@
+# libraries/shared/multi-arch -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2018-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Libraries::Shared::MultiArch;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(none uniq);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has shared_libraries => (is => 'rw', default => sub { [] });
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ m{^ [^,]* \b ELF \b }x;
+
+    return
+      unless $item->file_type
+      =~ m{(?: shared [ ] object | pie [ ] executable )}x;
+
+    my @ldconfig_folders = @{$self->data->architectures->ldconfig_folders};
+    return
+      if none { $item->dirname eq $_ } @ldconfig_folders;
+
+    push(@{$self->shared_libraries}, $item->name);
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    $self->hint(
+        'shared-library-is-multi-arch-foreign',
+        (sort +uniq @{$self->shared_libraries})
+      )
+      if @{$self->shared_libraries}
+      && $self->processable->fields->value('Multi-Arch') eq 'foreign';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Libraries/Shared/Obsolete.pm b/lib/Lintian/Check/Libraries/Shared/Obsolete.pm
new file mode 100644
index 0000000..699b70c
--- /dev/null
+++ b/lib/Lintian/Check/Libraries/Shared/Obsolete.pm
@@ -0,0 +1,56 @@
+# libraries/shared/obsolete -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Mo Zhou
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Libraries::Shared::Obsolete;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /^[^,]*\bELF\b/;
+
+    my @needed = @{$item->elf->{NEEDED} // []};
+    my @obsolete = grep { /^libcblas\.so\.\d/ } @needed;
+
+    $self->pointed_hint('linked-with-obsolete-library', $item->pointer, $_)
+      for @obsolete;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Libraries/Shared/Relocation.pm b/lib/Lintian/Check/Libraries/Shared/Relocation.pm
new file mode 100644
index 0000000..8c3dac9
--- /dev/null
+++ b/lib/Lintian/Check/Libraries/Shared/Relocation.pm
@@ -0,0 +1,58 @@
+# libraries/shared/relocation -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2018-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Libraries::Shared::Relocation;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # shared library
+    return
+      unless @{$item->elf->{SONAME} // [] };
+
+    # Now that we're sure this is really a shared library, report on
+    # non-PIC problems.
+    $self->pointed_hint('specific-address-in-shared-library', $item->pointer)
+      if $item->elf->{TEXTREL};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Libraries/Shared/Soname.pm b/lib/Lintian/Check/Libraries/Shared/Soname.pm
new file mode 100644
index 0000000..9887e3b
--- /dev/null
+++ b/lib/Lintian/Check/Libraries/Shared/Soname.pm
@@ -0,0 +1,123 @@
+# libraries/shared/soname -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Libraries::Shared::Soname;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any none uniq);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+
+has DEB_HOST_MULTIARCH => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->architectures->deb_host_multiarch;
+    }
+);
+
+sub installable {
+    my ($self) = @_;
+
+    return
+      if $self->processable->type eq 'udeb';
+
+    my $architecture = $self->processable->fields->value('Architecture');
+    my $multiarch_component = $self->DEB_HOST_MULTIARCH->{$architecture};
+
+    my @common_folders = qw{lib usr/lib};
+    push(@common_folders, map { "$_/$multiarch_component" } @common_folders)
+      if length $multiarch_component;
+
+    my @duplicated;
+    for my $item (@{$self->processable->installed->sorted_list}) {
+
+        # For the package naming check, filter out SONAMEs where all the
+        # files are at paths other than /lib, /usr/lib and /usr/lib/<MA-DIR>.
+        # This avoids false positives with plugins like Apache modules,
+        # which may have their own SONAMEs but which don't matter for the
+        # purposes of this check.
+        next
+          if none { $item->dirname eq $_ . $SLASH } @common_folders;
+
+        # Also filter out nsswitch modules
+        next
+          if $item->basename =~ m{^ libnss_[^.]+\.so(?:\.\d+) $}x;
+
+        push(@duplicated, @{$item->elf->{SONAME} // []});
+    }
+
+    my @sonames = uniq @duplicated;
+
+    # try to strip transition strings
+    my $shortened_name = $self->processable->name;
+    $shortened_name =~ s/c102\b//;
+    $shortened_name =~ s/c2a?\b//;
+    $shortened_name =~ s/\dg$//;
+    $shortened_name =~ s/gf$//;
+    $shortened_name =~ s/v[5-6]$//; # GCC-5 / libstdc++6 C11 ABI breakage
+    $shortened_name =~ s/-udeb$//;
+    $shortened_name =~ s/^lib64/lib/;
+
+    my $match_found = 0;
+    for my $soname (@sonames) {
+
+        $soname =~ s/ ([0-9]) [.]so[.] /$1-/x;
+        $soname =~ s/ [.]so (?:[.]|\z) //x;
+        $soname =~ s/_/-/g;
+
+        my $lowercase = lc $soname;
+
+        $match_found = any { $lowercase eq $_ }
+          ($self->processable->name, $shortened_name);
+
+        last
+          if $match_found;
+    }
+
+    $self->hint('package-name-doesnt-match-sonames',
+        join($SPACE, sort @sonames))
+      if @sonames && !$match_found;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Libraries/Shared/Soname/Missing.pm b/lib/Lintian/Check/Libraries/Shared/Soname/Missing.pm
new file mode 100644
index 0000000..a01a878
--- /dev/null
+++ b/lib/Lintian/Check/Libraries/Shared/Soname/Missing.pm
@@ -0,0 +1,73 @@
+# libraries/shared/soname/missing -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2018-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Libraries::Shared::Soname::Missing;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(none);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ m{^ [^,]* \b ELF \b }x;
+
+    return
+      unless $item->file_type
+      =~ m{(?: shared [ ] object | pie [ ] executable )}x;
+
+    # does not have SONAME
+    return
+      if @{$item->elf->{SONAME} // [] };
+
+    my @ldconfig_folders = @{$self->data->architectures->ldconfig_folders};
+    return
+      if none { $item->dirname eq $_ } @ldconfig_folders;
+
+    # disregard executables
+    $self->pointed_hint('sharedobject-in-library-directory-missing-soname',
+        $item->pointer)
+      if !$item->is_executable
+      || !defined $item->elf->{DEBUG}
+      || $item->name =~ / [.]so (?: [.] | $ ) /msx;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Libraries/Shared/Stack.pm b/lib/Lintian/Check/Libraries/Shared/Stack.pm
new file mode 100644
index 0000000..f3e1d03
--- /dev/null
+++ b/lib/Lintian/Check/Libraries/Shared/Stack.pm
@@ -0,0 +1,69 @@
+# libraries/shared/stack -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2018-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Libraries::Shared::Stack;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # shared library
+    return
+      unless @{$item->elf->{SONAME} // [] };
+
+    $self->pointed_hint('shared-library-lacks-stack-section',$item->pointer)
+      if $self->processable->fields->declares('Architecture')
+      && !exists $item->elf->{PH}{STACK};
+
+    $self->pointed_hint('executable-stack-in-shared-library', $item->pointer)
+      if exists $item->elf->{PH}{STACK}
+      && $item->elf->{PH}{STACK}{flags} ne 'rw-'
+     # Once the following line is removed again, please also remove
+     # the Test-Architectures line in
+     # t/recipes/checks/libraries/shared/stack/shared-libs-exec-stack/eval/desc
+     # and the MIPS-related notes in
+     # tags/e/executable-stack-in-shared-library.tag. See
+     # https://bugs.debian.org/1025436 and
+     # https://bugs.debian.org/1022787 for details
+      && $self->processable->fields->value('Architecture') !~ /mips/;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Libraries/Shared/Trigger/Ldconfig.pm b/lib/Lintian/Check/Libraries/Shared/Trigger/Ldconfig.pm
new file mode 100644
index 0000000..66f5961
--- /dev/null
+++ b/lib/Lintian/Check/Libraries/Shared/Trigger/Ldconfig.pm
@@ -0,0 +1,131 @@
+# libraries/shared/trigger/ldconfig -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2018-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Libraries::Shared::Trigger::Ldconfig;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(any uniq);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has soname_by_filename => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %soname_by_filename;
+        for my $item (@{$self->processable->installed->sorted_list}) {
+
+            $soname_by_filename{$item->name}= $item->elf->{SONAME}[0]
+              if exists $item->elf->{SONAME};
+        }
+
+        return \%soname_by_filename;
+    }
+);
+
+has must_call_ldconfig => (is => 'rw', default => sub { [] });
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    my $resolved_name = $item->name;
+    $resolved_name = $item->link_normalized
+      if length $item->link;
+
+    # Installed in a directory controlled by the dynamic
+    # linker?  We have to strip off directories named for
+    # hardware capabilities.
+    # yes! so postinst must call ldconfig
+    push(@{$self->must_call_ldconfig}, $resolved_name)
+      if exists $self->soname_by_filename->{$resolved_name}
+      && $self->needs_ldconfig($item);
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    # determine if the package had an ldconfig trigger
+    my $triggers = $self->processable->control->resolve_path('triggers');
+
+    my $we_trigger_ldconfig = 0;
+    $we_trigger_ldconfig = 1
+      if defined $triggers
+      && $triggers->decoded_utf8
+      =~ /^ \s* activate-noawait \s+ ldconfig \s* $/mx;
+
+    $self->hint('package-has-unnecessary-activation-of-ldconfig-trigger')
+      if !@{$self->must_call_ldconfig}
+      && $we_trigger_ldconfig
+      && $self->processable->type ne 'udeb';
+
+    $self->hint('lacks-ldconfig-trigger',
+        (sort +uniq @{$self->must_call_ldconfig}))
+      if @{$self->must_call_ldconfig}
+      && !$we_trigger_ldconfig
+      && $self->processable->type ne 'udeb';
+
+    return;
+}
+
+sub needs_ldconfig {
+    my ($self, $item) = @_;
+
+   # Libraries that should only be used in the presence of certain capabilities
+   # may be located in subdirectories of the standard ldconfig search path with
+   # one of the following names.
+    my $HWCAP_DIRS = $self->data->load('shared-libs/hwcap-dirs');
+    my @ldconfig_folders = @{$self->data->architectures->ldconfig_folders};
+
+    my $dirname = $item->dirname;
+    my $encapsulator;
+    do {
+        $dirname =~ s{ ([^/]+) / $}{}x;
+        $encapsulator = $1;
+
+    } while ($encapsulator && $HWCAP_DIRS->recognizes($encapsulator));
+
+    $dirname .= "$encapsulator/" if $encapsulator;
+
+    # yes! so postinst must call ldconfig
+    return 1
+      if any { $dirname eq $_ } @ldconfig_folders;
+
+    return 0;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Libraries/Static.pm b/lib/Lintian/Check/Libraries/Static.pm
new file mode 100644
index 0000000..72c8b97
--- /dev/null
+++ b/lib/Lintian/Check/Libraries/Static.pm
@@ -0,0 +1,121 @@
+# libraries/static -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Libraries::Static;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::Compare;
+use List::SomeUtils qw(any none uniq);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SPACE => q{ };
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ m{ \b current [ ] ar [ ] archive \b }x;
+
+    my @unstripped_members;
+    my %stripped_sections_by_member;
+
+    for my $member_name (keys %{$item->elf_by_member}) {
+
+        my $member_elf = $item->elf_by_member->{$member_name};
+
+        my @elf_sections = values %{$member_elf->{'SECTION-HEADERS'}};
+        my @have_section_names = map { $_->name } @elf_sections;
+
+        # These are the ones file(1) looks for.  The ".zdebug_info" being the
+        # compressed version of .debug_info.
+        # - Technically, file(1) also looks for .symtab, but that is apparently
+        #   not strippable for static libs.  Accordingly, it is omitted below.
+        my @KNOWN_DEBUG_SECTION_NAMES = qw{.debug_info .zdebug_info};
+        my $lc_debug = List::Compare->new(\@have_section_names,
+            \@KNOWN_DEBUG_SECTION_NAMES);
+
+        my @have_debug_sections = $lc_debug->get_intersection;
+
+        if (@have_debug_sections) {
+
+            push(@unstripped_members, $member_name);
+            next;
+        }
+
+        my @KNOWN_STRIPPED_SECTION_NAMES = qw{.note .comment};
+        my $lc_stripped = List::Compare->new(\@have_section_names,
+            \@KNOWN_STRIPPED_SECTION_NAMES);
+
+        my @have_stripped_sections = $lc_stripped->get_intersection;
+
+        $stripped_sections_by_member{$member_name} //= [];
+        push(
+            @{$stripped_sections_by_member{$member_name}},
+            @have_stripped_sections
+        );
+    }
+
+    $self->pointed_hint('unstripped-static-library', $item->pointer,
+        $LEFT_PARENTHESIS
+          . join($SPACE, sort +uniq @unstripped_members)
+          . $RIGHT_PARENTHESIS)
+      if @unstripped_members
+      && $item->name !~ m{ _g [.]a $}x;
+
+    # "libfoo_g.a" is usually a "debug" library, so ignore
+    # unneeded sections in those.
+    for my $member (keys %stripped_sections_by_member) {
+
+        $self->pointed_hint(
+            'static-library-has-unneeded-sections',
+            $item->pointer,
+            "($member)",
+            join($SPACE, sort +uniq @{$stripped_sections_by_member{$member}})
+          )
+          if @{$stripped_sections_by_member{$member}}
+          && $item->name !~ m{ _g [.]a $}x;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Libraries/Static/LinkTimeOptimization.pm b/lib/Lintian/Check/Libraries/Static/LinkTimeOptimization.pm
new file mode 100644
index 0000000..04e65e8
--- /dev/null
+++ b/lib/Lintian/Check/Libraries/Static/LinkTimeOptimization.pm
@@ -0,0 +1,70 @@
+# libraries/static/link-time-optimization -- lintian check script -*- perl -*-
+
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Libraries::Static::LinkTimeOptimization;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(uniq);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # not sure if that captures everything GHC, or too much
+    return
+      if $item->name =~ m{^ usr/lib/ghc/ }x;
+
+    return
+      unless $item->file_type =~ m{ \b current [ ] ar [ ] archive \b }x;
+
+    for my $member_name (keys %{$item->elf_by_member}) {
+
+        my $member_elf = $item->elf_by_member->{$member_name};
+
+        my @elf_sections = values %{$member_elf->{'SECTION-HEADERS'}};
+        my @section_names = map { $_->name } @elf_sections;
+
+        my @lto_section_names = grep { m{^ [.]gnu[.]lto }x } @section_names;
+
+        $self->pointed_hint('static-link-time-optimization',
+            $item->pointer, $member_name)
+          if @lto_section_names;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Libraries/Static/Name.pm b/lib/Lintian/Check/Libraries/Static/Name.pm
new file mode 100644
index 0000000..a4c47d1
--- /dev/null
+++ b/lib/Lintian/Check/Libraries/Static/Name.pm
@@ -0,0 +1,61 @@
+# libraries/static/name -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Libraries::Static::Name;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ m{ \b current [ ] ar [ ] archive \b }x;
+
+    my $shortened = $item->name;
+
+    if ($shortened =~ s{ _s[.]a $}{.a}x) {
+
+        $self->pointed_hint('odd-static-library-name', $item->pointer)
+          unless defined $self->processable->installed->lookup($shortened);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Libraries/Static/NoCode.pm b/lib/Lintian/Check/Libraries/Static/NoCode.pm
new file mode 100644
index 0000000..0d2415a
--- /dev/null
+++ b/lib/Lintian/Check/Libraries/Static/NoCode.pm
@@ -0,0 +1,95 @@
+# libraries/static/no-code -- lintian check script -*- perl -*-
+
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Libraries::Static::NoCode;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any uniq);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SPACE => q{ };
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    # not sure if that captures everything GHC, or too much
+    return
+      if $item->name =~ m{^ usr/lib/ghc/ }x;
+
+    return
+      unless $item->file_type =~ m{ \b current [ ] ar [ ] archive \b }x;
+
+    my @codeful_members;
+    for my $member_name (keys %{$item->elf_by_member}) {
+
+        my $member_elf = $item->elf_by_member->{$member_name};
+
+        my @elf_sections = values %{$member_elf->{'SECTION-HEADERS'}};
+        my @sections_with_size = grep { $_->size > 0 } @elf_sections;
+
+        my @names_with_size = map { $_->name } @sections_with_size;
+
+        my @KNOWN_ARRAY_SECTIONS = qw{.preinit_array .init_array .fini_array};
+        my $lc_array
+          = List::Compare->new(\@names_with_size, \@KNOWN_ARRAY_SECTIONS);
+
+        my @have_array_sections = $lc_array->get_intersection;
+
+# adapted from https://github.com/rpm-software-management/rpmlint/blob/main/rpmlint/checks/BinariesCheck.py#L242-L249
+        my $has_code = 0;
+
+        $has_code = 1
+          if any { m{^ [.]text }x } @names_with_size;
+
+        $has_code = 1
+          if any { m{^ [.]data }x } @names_with_size;
+
+        $has_code = 1
+          if @have_array_sections;
+
+        push(@codeful_members, $member_name)
+          if $has_code;
+    }
+
+    $self->pointed_hint('no-code-sections', $item->pointer)
+      unless @codeful_members;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Linda.pm b/lib/Lintian/Check/Linda.pm
new file mode 100644
index 0000000..f7dcca8
--- /dev/null
+++ b/lib/Lintian/Check/Linda.pm
@@ -0,0 +1,47 @@
+# linda -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Linda;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    $self->pointed_hint('package-contains-linda-override', $item->pointer)
+      if $item->name =~ m{^usr/share/linda/overrides/\S+};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Lintian.pm b/lib/Lintian/Check/Lintian.pm
new file mode 100644
index 0000000..abfcccc
--- /dev/null
+++ b/lib/Lintian/Check/Lintian.pm
@@ -0,0 +1,38 @@
+# Lintian -- lintian check script (rewrite) -*- perl -*-
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Lintian;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Mailcap.pm b/lib/Lintian/Check/Mailcap.pm
new file mode 100644
index 0000000..2588d43
--- /dev/null
+++ b/lib/Lintian/Check/Mailcap.pm
@@ -0,0 +1,108 @@
+# mailcap -- lintian check script -*- perl -*-
+
+# Copyright (C) 2019 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Mailcap;
+
+use v5.20;
+use warnings;
+use utf8;
+use autodie qw(open);
+
+use Const::Fast;
+use List::SomeUtils qw(uniq);
+use Text::Balanced qw(extract_delimited extract_multiple);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->name =~ m{^usr/lib/mime/packages/};
+
+    return
+      unless $item->is_file && $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path);
+
+    my @continuation;
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        unless (@continuation) {
+            # skip blank lines
+            next
+              if $line =~ /^\s*$/;
+
+            # skip comments
+            next
+              if $line =~ /^\s*#/;
+        }
+
+        # continuation line
+        if ($line =~ s/\\$//) {
+            push(@continuation, {string => $line, position => $position});
+            next;
+        }
+
+        push(@continuation, {string => $line, position => $position});
+
+        my $assembled = $EMPTY;
+        $assembled .= $_->{string} for @continuation;
+
+        my $start_position = $continuation[0]->{position};
+
+        my @quoted
+          = extract_multiple($assembled,
+            [sub { extract_delimited($_[0], q{"'}, '[^\'"]*') }],
+            undef, 1);
+
+        my @placeholders = uniq grep { /\%s/ } @quoted;
+
+        $self->pointed_hint(
+            'quoted-placeholder-in-mailcap-entry',
+            $item->pointer($start_position),
+            @placeholders
+        )if @placeholders;
+
+        @continuation = ();
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/MaintainerScripts/Adduser.pm b/lib/Lintian/Check/MaintainerScripts/Adduser.pm
new file mode 100644
index 0000000..f8bbea4
--- /dev/null
+++ b/lib/Lintian/Check/MaintainerScripts/Adduser.pm
@@ -0,0 +1,96 @@
+# maintainer_scripts::adduser -- lintian check script -*- perl -*-
+
+# Copyright (C) 2020 Topi Miettinen
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::MaintainerScripts::Adduser;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    # get maintainer scripts
+    return
+      unless $item->is_maintainer_script;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $continuation = undef;
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        chomp $line;
+
+        # merge lines ending with '\'
+        if (defined $continuation) {
+            $line = $continuation . $line;
+            $continuation = undef;
+        }
+
+        if ($line =~ /\\$/) {
+            $continuation = $line;
+            $continuation =~ s/\\$/ /;
+            next;
+        }
+
+        # trim right
+        $line =~ s/\s+$//;
+
+        # skip empty lines
+        next
+          if $line =~ /^\s*$/;
+
+        # skip comments
+        next
+          if $line =~ /^[#\n]/;
+
+        $self->pointed_hint('adduser-with-home-var-run',
+            $item->pointer($position))
+          if $line =~ /adduser .*--home +\/var\/run/;
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/MaintainerScripts/AncientVersion.pm b/lib/Lintian/Check/MaintainerScripts/AncientVersion.pm
new file mode 100644
index 0000000..9fac1c5
--- /dev/null
+++ b/lib/Lintian/Check/MaintainerScripts/AncientVersion.pm
@@ -0,0 +1,180 @@
+# maintainer-scripts/ancient-version -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::MaintainerScripts::AncientVersion;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use POSIX qw(strftime);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+# date --date="Sat, 14 Aug 2021 17:41:41 -0400" +%s
+# https://lists.debian.org/debian-announce/2021/msg00003.html
+const my $OLDSTABLE_RELEASE_EPOCH => 1_628_977_301;
+
+# When detecting commands inside shell scripts, use this regex to match the
+# beginning of the command rather than checking whether the command is at the
+# beginning of a line.
+const my $LEADING_PATTERN=>
+'(?:(?:^|[`&;(|{])\s*|(?:if|then|do|while|!)\s+|env(?:\s+[[:alnum:]_]+=(?:\S+|\"[^"]*\"|\'[^\']*\'))*\s+)';
+const my $LEADING_REGEX => qr/$LEADING_PATTERN/;
+
+has old_versions => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %old_versions;
+        for my $entry (
+            $self->processable->changelog
+            ? @{$self->processable->changelog->entries}
+            : ()
+        ) {
+            my $timestamp = $entry->Timestamp // $OLDSTABLE_RELEASE_EPOCH;
+            $old_versions{$entry->Version} = $timestamp
+              if $timestamp < $OLDSTABLE_RELEASE_EPOCH;
+        }
+
+        return \%old_versions;
+    }
+);
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_maintainer_script;
+
+    return
+      unless length $item->interpreter;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $stashed = $EMPTY;
+
+    my $position = 1;
+    while (my $possible_continuation = <$fd>) {
+
+        chomp $possible_continuation;
+
+        # skip empty lines
+        next
+          if $possible_continuation =~ /^\s*$/;
+
+        # skip comment lines
+        next
+          if $possible_continuation =~ /^\s*\#/;
+
+        my $no_comment = remove_comments($possible_continuation);
+
+        # Concatenate lines containing continuation character (\)
+        # at the end
+        if ($no_comment =~ s{\\$}{}) {
+
+            $stashed .= $no_comment;
+
+            next;
+        }
+
+        my $line = $stashed . $no_comment;
+        $stashed = $EMPTY;
+
+        for my $old_version (keys %{$self->old_versions}) {
+
+            next
+              if $old_version =~ /^\d+$/;
+
+            if ($line
+                =~m{$LEADING_REGEX(?:/usr/bin/)?dpkg\s+--compare-versions\s+.*\b\Q$old_version\E(?!\.)\b}
+            ) {
+                my $date
+                  = strftime('%Y-%m-%d',
+                    gmtime $self->old_versions->{$old_version});
+                my $epoch
+                  = strftime('%Y-%m-%d', gmtime $OLDSTABLE_RELEASE_EPOCH);
+
+                my $pointer = $item->pointer($position);
+
+                $self->pointed_hint(
+                    'maintainer-script-supports-ancient-package-version',
+                    $pointer, $old_version,"($date < $epoch)",
+                );
+            }
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    return;
+}
+
+sub remove_comments {
+    my ($line) = @_;
+
+    return $line
+      unless length $line;
+
+    my $simplified = $line;
+
+    # Remove quoted strings so we can more easily ignore comments
+    # inside them
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\'(?:\\.|[^\\\'])+\'/$1''/g;
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\"(?:\\.|[^\\\"])+\"/$1""/g;
+
+    # If the remaining string contains what looks like a comment,
+    # eat it. In either case, swap the unmodified script line
+    # back in for processing (if required) and return it.
+    if ($simplified =~ m/(?:^|[^[\\])[\s\&;\(\)](\#.*$)/) {
+
+        my $comment = $1;
+
+        # eat comment
+        $line =~ s/\Q$comment\E//;
+    }
+
+    return $line;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/MaintainerScripts/Diversion.pm b/lib/Lintian/Check/MaintainerScripts/Diversion.pm
new file mode 100644
index 0000000..e786422
--- /dev/null
+++ b/lib/Lintian/Check/MaintainerScripts/Diversion.pm
@@ -0,0 +1,369 @@
+# maintainer-scripts/diversion -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::MaintainerScripts::Diversion;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any none);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+# When detecting commands inside shell scripts, use this regex to match the
+# beginning of the command rather than checking whether the command is at the
+# beginning of a line.
+const my $LEADING_PATTERN=>
+'(?:(?:^|[`&;(|{])\s*|(?:if|then|do|while|!)\s+|env(?:\s+[[:alnum:]_]+=(?:\S+|\"[^"]*\"|\'[^\']*\'))*\s+)';
+const my $LEADING_REGEX => qr/$LEADING_PATTERN/;
+
+has added_diversions => (is => 'rw', default => sub { {} });
+has removed_diversions => (is => 'rw', default => sub { {} });
+has expand_diversions => (is => 'rw', default => 0);
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_maintainer_script;
+
+    return
+      unless length $item->interpreter;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $stashed = $EMPTY;
+
+    my $position = 1;
+    while (my $possible_continuation = <$fd>) {
+
+        my $pointer = $item->pointer($position);
+
+        chomp $possible_continuation;
+
+        # skip empty lines
+        next
+          if $possible_continuation =~ /^\s*$/;
+
+        # skip comment lines
+        next
+          if $possible_continuation =~ /^\s*\#/;
+
+        my $no_comment = remove_comments($possible_continuation);
+
+        # Concatenate lines containing continuation character (\)
+        # at the end
+        if ($no_comment =~ s{\\$}{}) {
+
+            $stashed .= $no_comment;
+
+            next;
+        }
+
+        my $line = $stashed . $no_comment;
+        $stashed = $EMPTY;
+
+        if (   $line =~ m{$LEADING_REGEX(?:/usr/sbin/)?dpkg-divert\s}
+            && $line !~ /--(?:help|list|truename|version)/) {
+
+            $self->pointed_hint('package-uses-local-diversion',$pointer)
+              if $line =~ /--local/;
+
+            my $mode = $line =~ /--remove/ ? 'remove' : 'add';
+
+            my ($divert) = ($line =~ /dpkg-divert\s*(.*)$/);
+
+            $divert =~ s{\s*(?:\$[{]?[\w:=-]+[}]?)*\s*
+                                # options without arguments
+                              --(?:add|quiet|remove|rename|no-rename|test|local
+                                # options with arguments
+                                |(?:admindir|divert|package) \s+ \S+)
+                              \s*}{}gxsm;
+
+            # Remove unpaired opening or closing parenthesis
+            1 while ($divert =~ m/\G.*?\(.+?\)/gc);
+            $divert =~ s/\G(.*?)[()]/$1/;
+            pos($divert) = undef;
+
+            # Remove unpaired opening or closing braces
+            1 while ($divert =~ m/\G.*?{.+?}/gc);
+            $divert =~ s/\G(.*?)[{}]/$1/;
+            pos($divert) = undef;
+
+            # position after the last pair of quotation marks, if any
+            1 while ($divert =~ m/\G.*?(["']).+?\1/gc);
+
+            # Strip anything matching and after '&&', '||', ';', or '>'
+            # this is safe only after we are positioned after the last pair
+            # of quotation marks
+            $divert =~ s/\G.+?\K(?: && | \|\| | ; | \d*> ).*$//x;
+            pos($divert) = undef;
+
+            # Remove quotation marks, they affect:
+            # * our var to regex trick
+            # * stripping the initial slash if the path was quoted
+            $divert =~ s/[\"\']//g;
+
+            # remove the leading / because it's not in the index hash
+            $divert =~ s{^/}{};
+
+            # trim both ends
+            $divert =~ s/^\s+|\s+$//g;
+
+            $divert = quotemeta($divert);
+
+            # For now just replace variables, they will later be normalised
+            $self->expand_diversions(1)
+              if $divert =~ s/\\\$\w+/.+/g;
+
+            $self->expand_diversions(1)
+              if $divert =~ s/\\\$\\[{]\w+.*?\\[}]/.+/g;
+
+            # handle $() the same way:
+            $self->expand_diversions(1)
+              if $divert =~ s/\\\$\\\(.+?\\\)/.+/g;
+
+            my %diversion;
+            $diversion{script} = $item;
+            $diversion{position} = $position;
+
+            $self->added_diversions->{$divert} = \%diversion
+              if $mode eq 'add';
+
+            push(@{$self->removed_diversions->{$divert}}, \%diversion)
+              if $mode eq 'remove';
+
+            die encode_utf8("mode has unknown value: $mode")
+              if none { $mode eq $_ } qw{add remove};
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    # If any of the maintainer scripts used a variable in the file or
+    # diversion name normalise them all
+    if ($self->expand_diversions) {
+
+        for my $divert (
+            keys %{$self->removed_diversions},
+            keys %{$self->added_diversions}
+        ) {
+
+            # if a wider regex was found, the entries might no longer be there
+            next
+              unless exists $self->removed_diversions->{$divert}
+              || exists $self->added_diversions->{$divert};
+
+            my $widerrx = $divert;
+            my $wider = $widerrx;
+            $wider =~ s/\\//g;
+
+            # find the widest regex:
+            my @matches = grep {
+                my $lrx = $_;
+                my $l = $lrx;
+                $l =~ s/\\//g;
+
+                if ($wider =~ m/^$lrx$/) {
+                    $widerrx = $lrx;
+                    $wider = $l;
+                    1;
+                } elsif ($l =~ m/^$widerrx$/) {
+                    1;
+                } else {
+                    0;
+                }
+            } (
+                keys %{$self->removed_diversions},
+                keys %{$self->added_diversions}
+            );
+
+            # replace all the occurrences with the widest regex:
+            for my $k (@matches) {
+
+                next
+                  if $k eq $widerrx;
+
+                if (exists $self->removed_diversions->{$k}) {
+
+                    $self->removed_diversions->{$widerrx}
+                      = $self->removed_diversions->{$k};
+
+                    delete $self->removed_diversions->{$k};
+                }
+
+                if (exists $self->added_diversions->{$k}) {
+
+                    $self->added_diversions->{$widerrx}
+                      = $self->added_diversions->{$k};
+
+                    delete $self->added_diversions->{$k};
+                }
+            }
+        }
+    }
+
+    for my $divert (keys %{$self->removed_diversions}) {
+
+        if (exists $self->added_diversions->{$divert}) {
+            # just mark the entry, because a --remove might
+            # happen in two branches in the script, i.e. we
+            # see it twice, which is not a bug
+            $self->added_diversions->{$divert}{removed} = 1;
+
+        } else {
+
+            for my $item (@{$self->removed_diversions->{$divert}}) {
+
+                my $script = $item->{script};
+                my $position = $item->{position};
+
+                next
+                  unless $script->name eq 'postrm';
+
+                # Allow preinst and postinst to remove diversions the
+                # package doesn't add to clean up after previous
+                # versions of the package.
+
+                my $unquoted = unquote($divert, $self->expand_diversions);
+
+                my $pointer = $script->pointer($position);
+
+                $self->pointed_hint('remove-of-unknown-diversion', $pointer,
+                    $unquoted);
+            }
+        }
+    }
+
+    for my $divert (keys %{$self->added_diversions}) {
+
+        my $script = $self->added_diversions->{$divert}{script};
+        my $position = $self->added_diversions->{$divert}{position};
+
+        my $pointer = $script->pointer($script);
+        $pointer->position($position);
+
+        my $divertrx = $divert;
+        my $unquoted = unquote($divert, $self->expand_diversions);
+
+        $self->pointed_hint('orphaned-diversion', $pointer, $unquoted)
+          unless exists $self->added_diversions->{$divertrx}{removed};
+
+        # Handle man page diversions somewhat specially.  We may
+        # divert away a man page in one section without replacing that
+        # same file, since we're installing a man page in a different
+        # section.  An example is diverting a man page in section 1
+        # and replacing it with one in section 1p (such as
+        # libmodule-corelist-perl at the time of this writing).
+        #
+        # Deal with this by turning all man page diversions into
+        # wildcard expressions instead that match everything in the
+        # same numeric section so that they'll match the files shipped
+        # in the package.
+        if ($divertrx =~ m{^(usr\\/share\\/man\\/\S+\\/.*\\\.\d)\w*(\\\.gz\z)})
+        {
+            $divertrx = "$1.*$2";
+            $self->expand_diversions(1);
+        }
+
+        if ($self->expand_diversions) {
+
+            $self->pointed_hint('diversion-for-unknown-file', $pointer,
+                $unquoted)
+              unless (any { /$divertrx/ }
+                @{$self->processable->installed->sorted_list});
+
+        } else {
+            $self->pointed_hint('diversion-for-unknown-file', $pointer,
+                $unquoted)
+              unless $self->processable->installed->lookup($unquoted);
+        }
+    }
+
+    return;
+}
+
+sub remove_comments {
+    my ($line) = @_;
+
+    return $line
+      unless length $line;
+
+    my $simplified = $line;
+
+    # Remove quoted strings so we can more easily ignore comments
+    # inside them
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\'(?:\\.|[^\\\'])+\'/$1''/g;
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\"(?:\\.|[^\\\"])+\"/$1""/g;
+
+    # If the remaining string contains what looks like a comment,
+    # eat it. In either case, swap the unmodified script line
+    # back in for processing (if required) and return it.
+    if ($simplified =~ m/(?:^|[^[\\])[\s\&;\(\)](\#.*$)/) {
+
+        my $comment = $1;
+
+        # eat comment
+        $line =~ s/\Q$comment\E//;
+    }
+
+    return $line;
+}
+
+sub unquote {
+    my ($string, $replace_regex) = @_;
+
+    $string =~ s{\\}{}g;
+
+    $string =~ s{\.\+}{*}g
+      if $replace_regex;
+
+    return $string;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/MaintainerScripts/DpkgStatoverride.pm b/lib/Lintian/Check/MaintainerScripts/DpkgStatoverride.pm
new file mode 100644
index 0000000..6b8347c
--- /dev/null
+++ b/lib/Lintian/Check/MaintainerScripts/DpkgStatoverride.pm
@@ -0,0 +1,148 @@
+# maintainer-scripts/dpkg-statoverride -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::MaintainerScripts::DpkgStatoverride;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+# When detecting commands inside shell scripts, use this regex to match the
+# beginning of the command rather than checking whether the command is at the
+# beginning of a line.
+const my $LEADING_PATTERN=>
+'(?:(?:^|[`&;(|{])\s*|(?:if|then|do|while|!)\s+|env(?:\s+[[:alnum:]_]+=(?:\S+|\"[^"]*\"|\'[^\']*\'))*\s+)';
+const my $LEADING_REGEX => qr/$LEADING_PATTERN/;
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_maintainer_script;
+
+    return
+      unless length $item->interpreter;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $stashed = $EMPTY;
+
+    my $saw_statoverride_list = 0;
+
+    my $position = 1;
+    while (my $possible_continuation = <$fd>) {
+
+        my $pointer = $item->pointer($position);
+
+        chomp $possible_continuation;
+
+        # skip empty lines
+        next
+          if $possible_continuation =~ /^\s*$/;
+
+        # skip comment lines
+        next
+          if $possible_continuation =~ /^\s*\#/;
+
+        my $no_comment = remove_comments($possible_continuation);
+
+        # Concatenate lines containing continuation character (\)
+        # at the end
+        if ($no_comment =~ s{\\$}{}) {
+
+            $stashed .= $no_comment;
+
+            next;
+        }
+
+        my $line = $stashed . $no_comment;
+        $stashed = $EMPTY;
+
+        if ($line =~ m{$LEADING_REGEX(?:/usr/bin/)?dpkg-statoverride\s}) {
+
+            $saw_statoverride_list = 1
+              if $line =~ /--list/;
+
+            if ($line =~ /--add/) {
+
+                $self->pointed_hint('unconditional-use-of-dpkg-statoverride',
+                    $pointer)
+                  unless $saw_statoverride_list;
+            }
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    return;
+}
+
+sub remove_comments {
+    my ($line) = @_;
+
+    return $line
+      unless length $line;
+
+    my $simplified = $line;
+
+    # Remove quoted strings so we can more easily ignore comments
+    # inside them
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\'(?:\\.|[^\\\'])+\'/$1''/g;
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\"(?:\\.|[^\\\"])+\"/$1""/g;
+
+    # If the remaining string contains what looks like a comment,
+    # eat it. In either case, swap the unmodified script line
+    # back in for processing (if required) and return it.
+    if ($simplified =~ m/(?:^|[^[\\])[\s\&;\(\)](\#.*$)/) {
+
+        my $comment = $1;
+
+        # eat comment
+        $line =~ s/\Q$comment\E//;
+    }
+
+    return $line;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/MaintainerScripts/Empty.pm b/lib/Lintian/Check/MaintainerScripts/Empty.pm
new file mode 100644
index 0000000..298eb0a
--- /dev/null
+++ b/lib/Lintian/Check/MaintainerScripts/Empty.pm
@@ -0,0 +1,144 @@
+# maintainer-scripts/empty -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::MaintainerScripts::Empty;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_maintainer_script;
+
+    return
+      unless length $item->interpreter;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $stashed = $EMPTY;
+
+    my $has_code = 0;
+
+    my $position = 1;
+    while (my $possible_continuation = <$fd>) {
+
+        chomp $possible_continuation;
+
+        # skip empty lines
+        next
+          if $possible_continuation =~ /^\s*$/;
+
+        # skip comment lines
+        next
+          if $possible_continuation =~ /^\s*\#/;
+
+        my $no_comment = remove_comments($possible_continuation);
+
+        # Concatenate lines containing continuation character (\)
+        # at the end
+        if ($no_comment =~ s{\\$}{}) {
+
+            $stashed .= $no_comment;
+
+            next;
+        }
+
+        my $line = $stashed . $no_comment;
+        $stashed = $EMPTY;
+
+        # Don't consider the standard dh-make boilerplate to be code.  This
+        # means ignoring the framework of a case statement, the labels, the
+        # echo complaining about unknown arguments, and an exit.
+        if (   $line !~ /^\s*set\s+-\w+\s*$/
+            && $line !~ /^\s*case\s+\"?\$1\"?\s+in\s*$/
+            && $line !~ /^\s*(?:[a-z|-]+|\*)\)\s*$/
+            && $line !~ /^\s*[:;]+\s*$/
+            && $line !~ /^\s*echo\s+\"[^\"]+\"(?:\s*>&2)?\s*$/
+            && $line !~ /^\s*esac\s*$/
+            && $line !~ /^\s*exit\s+\d+\s*$/) {
+
+            $has_code = 1;
+            last;
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    $self->pointed_hint('maintainer-script-empty', $item->pointer)
+      unless $has_code;
+
+    return;
+}
+
+sub remove_comments {
+    my ($line) = @_;
+
+    return $line
+      unless length $line;
+
+    my $simplified = $line;
+
+    # Remove quoted strings so we can more easily ignore comments
+    # inside them
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\'(?:\\.|[^\\\'])+\'/$1''/g;
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\"(?:\\.|[^\\\"])+\"/$1""/g;
+
+    # If the remaining string contains what looks like a comment,
+    # eat it. In either case, swap the unmodified script line
+    # back in for processing (if required) and return it.
+    if ($simplified =~ m/(?:^|[^[\\])[\s\&;\(\)](\#.*$)/) {
+
+        my $comment = $1;
+
+        # eat comment
+        $line =~ s/\Q$comment\E//;
+    }
+
+    return $line;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/MaintainerScripts/Generated.pm b/lib/Lintian/Check/MaintainerScripts/Generated.pm
new file mode 100644
index 0000000..bf00910
--- /dev/null
+++ b/lib/Lintian/Check/MaintainerScripts/Generated.pm
@@ -0,0 +1,85 @@
+# maintainer-scripts/generated -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::MaintainerScripts::Generated;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(uniq);
+use Path::Tiny;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub installable {
+    my ($self) = @_;
+
+    my @tools_seen;
+
+    # get maintainer scripts
+    my @control
+      = grep { $_->is_maintainer_script }
+      @{$self->processable->control->sorted_list};
+
+    for my $file (@control) {
+
+        my $hashbang = $file->hashbang;
+        next
+          unless length $hashbang;
+
+        next
+          unless $file->is_open_ok;
+
+        my @lines = path($file->unpacked_path)->lines;
+
+        # scan contents
+        for (@lines) {
+
+            # skip empty lines
+            next
+              if /^\s*$/;
+
+            if (/^# Automatically added by (\S+)\s*$/) {
+                my $tool = $1;
+# remove trailing ":" from dh_python
+# https://sources.debian.org/src/dh-python/4.20191017/dhpython/debhelper.py/#L200
+                $tool =~ s/:\s*$//g;
+                push(@tools_seen, $tool);
+            }
+        }
+    }
+
+    $self->hint('debhelper-autoscript-in-maintainer-scripts', $_)
+      for uniq @tools_seen;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/MaintainerScripts/Helper/Dpkg.pm b/lib/Lintian/Check/MaintainerScripts/Helper/Dpkg.pm
new file mode 100644
index 0000000..ef87c40
--- /dev/null
+++ b/lib/Lintian/Check/MaintainerScripts/Helper/Dpkg.pm
@@ -0,0 +1,183 @@
+# maintainer-scripts/helper/dpkg -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::MaintainerScripts::Helper::Dpkg;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::Compare;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+# When detecting commands inside shell scripts, use this regex to match the
+# beginning of the command rather than checking whether the command is at the
+# beginning of a line.
+const my $LEADING_PATTERN=>
+'(?:(?:^|[`&;(|{])\s*|(?:if|then|do|while|!)\s+|env(?:\s+[[:alnum:]_]+=(?:\S+|\"[^"]*\"|\'[^\']*\'))*\s+)';
+const my $LEADING_REGEX => qr/$LEADING_PATTERN/;
+
+has seen_helper_commands => (is => 'rw', default => sub { {} });
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_maintainer_script;
+
+    return
+      unless length $item->interpreter;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $stashed = $EMPTY;
+
+    my $position = 1;
+    while (my $possible_continuation = <$fd>) {
+
+        chomp $possible_continuation;
+
+        # skip empty lines
+        next
+          if $possible_continuation =~ /^\s*$/;
+
+        # skip comment lines
+        next
+          if $possible_continuation =~ /^\s*\#/;
+
+        my $no_comment = remove_comments($possible_continuation);
+
+        # Concatenate lines containing continuation character (\)
+        # at the end
+        if ($no_comment =~ s{\\$}{}) {
+
+            $stashed .= $no_comment;
+
+            next;
+        }
+
+        my $line = $stashed . $no_comment;
+        $stashed = $EMPTY;
+
+        if ($line
+            =~ m{$LEADING_REGEX(?:/usr/bin/)?dpkg-maintscript-helper\s(\S+)}){
+
+            my $command = $1;
+
+            $self->seen_helper_commands->{$command} //= [];
+            push(@{$self->seen_helper_commands->{$command}}, $item->name);
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    for my $command (keys %{$self->seen_helper_commands}) {
+
+        # entering the loop means there is at least one member
+        my @have = @{$self->seen_helper_commands->{$command} // [] };
+        next
+          unless @have;
+
+        # dpkg-maintscript-helper(1) recommends the snippets are in all
+        # maintainer scripts but they are not strictly required in prerm.
+        my @wanted = qw{preinst postinst postrm};
+
+        my $lc = List::Compare->new(\@wanted, \@have);
+
+        my @missing = $lc->get_Lonly;
+
+        for my $name (@missing) {
+
+            my $item = $self->processable->control->lookup($name);
+
+            if (defined $item) {
+
+                $self->pointed_hint('missing-call-to-dpkg-maintscript-helper',
+                    $item->pointer, $command);
+
+            } else {
+                # file does not exist
+                $self->hint('missing-call-to-dpkg-maintscript-helper',
+                    $command, "[$name]");
+            }
+        }
+    }
+
+    return;
+}
+
+sub remove_comments {
+    my ($line) = @_;
+
+    return $line
+      unless length $line;
+
+    my $simplified = $line;
+
+    # Remove quoted strings so we can more easily ignore comments
+    # inside them
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\'(?:\\.|[^\\\'])+\'/$1''/g;
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\"(?:\\.|[^\\\"])+\"/$1""/g;
+
+    # If the remaining string contains what looks like a comment,
+    # eat it. In either case, swap the unmodified script line
+    # back in for processing (if required) and return it.
+    if ($simplified =~ m/(?:^|[^[\\])[\s\&;\(\)](\#.*$)/) {
+
+        my $comment = $1;
+
+        # eat comment
+        $line =~ s/\Q$comment\E//;
+    }
+
+    return $line;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/MaintainerScripts/Killall.pm b/lib/Lintian/Check/MaintainerScripts/Killall.pm
new file mode 100644
index 0000000..2c3dd09
--- /dev/null
+++ b/lib/Lintian/Check/MaintainerScripts/Killall.pm
@@ -0,0 +1,131 @@
+# maintainer-scripts/killall -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::MaintainerScripts::Killall;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_maintainer_script;
+
+    return
+      unless length $item->interpreter;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $stashed = $EMPTY;
+
+    my $position = 1;
+    while (my $possible_continuation = <$fd>) {
+
+        my $pointer = $item->pointer($position);
+
+        chomp $possible_continuation;
+
+        # skip empty lines
+        next
+          if $possible_continuation =~ /^\s*$/;
+
+        # skip comment lines
+        next
+          if $possible_continuation =~ /^\s*\#/;
+
+        my $no_comment = remove_comments($possible_continuation);
+
+        # Concatenate lines containing continuation character (\)
+        # at the end
+        if ($no_comment =~ s{\\$}{}) {
+
+            $stashed .= $no_comment;
+
+            next;
+        }
+
+        my $line = $stashed . $no_comment;
+        $stashed = $EMPTY;
+
+        $self->pointed_hint('killall-is-dangerous', $pointer)
+          if $line =~ /^\s*killall(?:\s|\z)/;
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+sub remove_comments {
+    my ($line) = @_;
+
+    return $line
+      unless length $line;
+
+    my $simplified = $line;
+
+    # Remove quoted strings so we can more easily ignore comments
+    # inside them
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\'(?:\\.|[^\\\'])+\'/$1''/g;
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\"(?:\\.|[^\\\"])+\"/$1""/g;
+
+    # If the remaining string contains what looks like a comment,
+    # eat it. In either case, swap the unmodified script line
+    # back in for processing (if required) and return it.
+    if ($simplified =~ m/(?:^|[^[\\])[\s\&;\(\)](\#.*$)/) {
+
+        my $comment = $1;
+
+        # eat comment
+        $line =~ s/\Q$comment\E//;
+    }
+
+    return $line;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/MaintainerScripts/Ldconfig.pm b/lib/Lintian/Check/MaintainerScripts/Ldconfig.pm
new file mode 100644
index 0000000..22e64d2
--- /dev/null
+++ b/lib/Lintian/Check/MaintainerScripts/Ldconfig.pm
@@ -0,0 +1,60 @@
+# maintainer-scripts/ldconfig -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2018-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::MaintainerScripts::Ldconfig;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_maintainer_script;
+
+    return
+      unless $item->decoded_utf8 =~ /^ [^\#]* \b ldconfig \b /mx;
+
+    $self->pointed_hint('udeb-postinst-calls-ldconfig', $item->pointer)
+      if $item->name eq 'postinst'
+      && $self->processable->type eq 'udeb';
+
+    $self->pointed_hint('maintscript-calls-ldconfig', $item->pointer)
+      if $item->name ne 'postinst'
+      || $self->processable->type ne 'udeb';
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/MaintainerScripts/Mknod.pm b/lib/Lintian/Check/MaintainerScripts/Mknod.pm
new file mode 100644
index 0000000..e7269ea
--- /dev/null
+++ b/lib/Lintian/Check/MaintainerScripts/Mknod.pm
@@ -0,0 +1,131 @@
+# maintainer-scripts/mknod -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::MaintainerScripts::Mknod;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_maintainer_script;
+
+    return
+      unless length $item->interpreter;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $stashed = $EMPTY;
+
+    my $position = 1;
+    while (my $possible_continuation = <$fd>) {
+
+        my $pointer = $item->pointer($position);
+
+        chomp $possible_continuation;
+
+        # skip empty lines
+        next
+          if $possible_continuation =~ /^\s*$/;
+
+        # skip comment lines
+        next
+          if $possible_continuation =~ /^\s*\#/;
+
+        my $no_comment = remove_comments($possible_continuation);
+
+        # Concatenate lines containing continuation character (\)
+        # at the end
+        if ($no_comment =~ s{\\$}{}) {
+
+            $stashed .= $no_comment;
+
+            next;
+        }
+
+        my $line = $stashed . $no_comment;
+        $stashed = $EMPTY;
+
+        $self->pointed_hint('mknod-in-maintainer-script', $pointer)
+          if $line =~ /^\s*mknod(?:\s|\z)/ && $line !~ /\sp\s/;
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+sub remove_comments {
+    my ($line) = @_;
+
+    return $line
+      unless length $line;
+
+    my $simplified = $line;
+
+    # Remove quoted strings so we can more easily ignore comments
+    # inside them
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\'(?:\\.|[^\\\'])+\'/$1''/g;
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\"(?:\\.|[^\\\"])+\"/$1""/g;
+
+    # If the remaining string contains what looks like a comment,
+    # eat it. In either case, swap the unmodified script line
+    # back in for processing (if required) and return it.
+    if ($simplified =~ m/(?:^|[^[\\])[\s\&;\(\)](\#.*$)/) {
+
+        my $comment = $1;
+
+        # eat comment
+        $line =~ s/\Q$comment\E//;
+    }
+
+    return $line;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/MaintainerScripts/Systemctl.pm b/lib/Lintian/Check/MaintainerScripts/Systemctl.pm
new file mode 100644
index 0000000..c5e1654
--- /dev/null
+++ b/lib/Lintian/Check/MaintainerScripts/Systemctl.pm
@@ -0,0 +1,76 @@
+# masitainer-scripts/systemctl -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2013 Michael Stapelberg
+# Copyright (C) 2016-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# based on the apache2 checks file by:
+# Copyright (C) 2012 Arno Toell
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::MaintainerScripts::Systemctl;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_maintainer_script;
+
+    # look only at shell scripts
+    return
+      unless $item->hashbang =~ /^\S*sh\b/;
+
+    my @lines = split(/\n/, $item->decoded_utf8);
+
+    my $position = 1;
+    for my $line (@lines) {
+
+        next
+          if $line =~ /^#/;
+
+        my $pointer = $item->pointer($position);
+
+        # systemctl should not be called in maintainer scripts at all,
+        # except for systemctl daemon-reload calls.
+        $self->pointed_hint('maintainer-script-calls-systemctl', $pointer)
+          if $line =~ /^(?:.+;)?\s*systemctl\b/
+          && $line !~ /daemon-reload/;
+
+    } continue {
+        ++$position;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/MaintainerScripts/TemporaryFiles.pm b/lib/Lintian/Check/MaintainerScripts/TemporaryFiles.pm
new file mode 100644
index 0000000..f6d1164
--- /dev/null
+++ b/lib/Lintian/Check/MaintainerScripts/TemporaryFiles.pm
@@ -0,0 +1,144 @@
+# maintainer-scripts/temporary-files -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::MaintainerScripts::TemporaryFiles;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_maintainer_script;
+
+    return
+      unless length $item->interpreter;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $stashed = $EMPTY;
+
+    my $position = 1;
+    while (my $possible_continuation = <$fd>) {
+
+        my $pointer = $item->pointer($position);
+
+        chomp $possible_continuation;
+
+        # skip empty lines
+        next
+          if $possible_continuation =~ /^\s*$/;
+
+        # skip comment lines
+        next
+          if $possible_continuation =~ /^\s*\#/;
+
+        my $no_comment = remove_comments($possible_continuation);
+
+        # Concatenate lines containing continuation character (\)
+        # at the end
+        if ($no_comment =~ s{\\$}{}) {
+
+            $stashed .= $no_comment;
+
+            next;
+        }
+
+        my $line = $stashed . $no_comment;
+        $stashed = $EMPTY;
+
+        if ($line =~  m{ \W ( (?:/var)?/tmp | \$TMPDIR /[^)\]\}\s]+ ) }x) {
+
+            my $indicator = $1;
+
+            $self->pointed_hint(
+                'possibly-insecure-handling-of-tmp-files-in-maintainer-script',
+                $pointer,
+                $indicator
+              )
+              if $line !~ /\bmks?temp\b/
+              && $line !~ /\btempfile\b/
+              && $line !~ /\bmkdir\b/
+              && $line !~ /\bXXXXXX\b/
+              && $line !~ /\$RANDOM/;
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+sub remove_comments {
+    my ($line) = @_;
+
+    return $line
+      unless length $line;
+
+    my $simplified = $line;
+
+    # Remove quoted strings so we can more easily ignore comments
+    # inside them
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\'(?:\\.|[^\\\'])+\'/$1''/g;
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\"(?:\\.|[^\\\"])+\"/$1""/g;
+
+    # If the remaining string contains what looks like a comment,
+    # eat it. In either case, swap the unmodified script line
+    # back in for processing (if required) and return it.
+    if ($simplified =~ m/(?:^|[^[\\])[\s\&;\(\)](\#.*$)/) {
+
+        my $comment = $1;
+
+        # eat comment
+        $line =~ s/\Q$comment\E//;
+    }
+
+    return $line;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Md5sums.pm b/lib/Lintian/Check/Md5sums.pm
new file mode 100644
index 0000000..c62d9cd
--- /dev/null
+++ b/lib/Lintian/Check/Md5sums.pm
@@ -0,0 +1,133 @@
+# md5sums -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2020 Felix Lechner
+# Copyright (C) 2018, 2020 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Md5sums;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::Compare;
+use Path::Tiny;
+
+use Lintian::Util qw(read_md5sums drop_relative_prefix);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has only_conffiles => (is => 'rw', default => 1);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # check if package contains non-conffiles
+    # debhelper doesn't create entries in md5sums
+    # for conffiles since this information would
+    # be redundant
+
+    # Skip non-files, they will not appear in the md5sums file
+    return
+      unless $item->is_regular_file;
+
+    $self->only_conffiles(0)
+      unless $self->processable->declared_conffiles->is_known($item->name);
+
+    return;
+}
+
+sub binary {
+    my ($self) = @_;
+
+    my $control = $self->processable->control->lookup('md5sums');
+    unless (defined $control) {
+
+        # ignore if package contains no files
+        return
+          unless @{$self->processable->installed->sorted_list};
+
+        $self->hint('no-md5sums-control-file')
+          unless $self->only_conffiles;
+
+        return;
+    }
+
+    # The md5sums file should not be a symlink.  If it is, the best
+    # we can do is to leave it alone.
+    return
+      if $control->is_symlink;
+
+    return
+      unless $control->is_open_ok;
+
+    # Is it empty? Then skip it. Tag will be issued by control-files
+    return
+      if $control->size == 0;
+
+    my $text = $control->bytes;
+
+    my ($md5sums, $errors) = read_md5sums($text);
+
+    $self->pointed_hint('malformed-md5sums-control-file',$control->pointer, $_)
+      for @{$errors};
+
+    my %noprefix
+      = map { drop_relative_prefix($_) => $md5sums->{$_} } keys %{$md5sums};
+
+    my @listed = keys %noprefix;
+    my @found
+      = grep { $_->is_file} @{$self->processable->installed->sorted_list};
+
+    my $lc = List::Compare->new(\@listed, \@found);
+
+    # find files that should exist but do not
+    $self->pointed_hint('md5sums-lists-nonexistent-file',$control->pointer, $_)
+      for $lc->get_Lonly;
+
+    # find files that should be listed but are not
+    for my $name ($lc->get_Ronly) {
+
+        $self->pointed_hint('file-missing-in-md5sums', $control->pointer,$name)
+          unless $self->processable->declared_conffiles->is_known($name)
+          || $name =~ m{^var/lib/[ai]spell/.};
+    }
+
+    # checksum should match for common files
+    for my $name ($lc->get_intersection) {
+
+        my $item = $self->processable->installed->lookup($name);
+
+        $self->pointed_hint('md5sum-mismatch', $control->pointer, $name)
+          unless $item->md5sum eq $noprefix{$name};
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/MenuFormat.pm b/lib/Lintian/Check/MenuFormat.pm
new file mode 100644
index 0000000..c9d40a8
--- /dev/null
+++ b/lib/Lintian/Check/MenuFormat.pm
@@ -0,0 +1,907 @@
+# menu format -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 by Joey Hess
+# Copyright (C) 2017-2018 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+# This script also checks desktop entries, since they share quite a bit of
+# code.  At some point, it would make sense to try to refactor this so that
+# shared code is in libraries.
+#
+# Further things that the desktop file validation should be checking:
+#
+#  - Encoding of the file should be UTF-8.
+#  - Additional Categories should be associated with Main Categories.
+#  - List entries (MimeType, Categories) should end with a semicolon.
+#  - Check for GNOME/GTK/X11/etc. dependencies and require the relevant
+#    Additional Category to be present.
+#  - Check all the escape characters supported by Exec.
+#  - Review desktop-file-validate to see what else we're missing.
+
+package Lintian::Check::MenuFormat;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use File::Basename;
+use List::SomeUtils qw(any first_value);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+
+const my $MAXIMUM_SIZE_STANDARD_ICON => 32;
+const my $MAXIMUM_SIZE_32X32_ICON => 32;
+const my $MAXIMUM_SIZE_16X16_ICON => 16;
+
+# This is a list of all tags that should be in every menu item.
+my @req_tags = qw(needs section title command);
+
+# This is a list of all known tags.
+my @known_tags = qw(
+  needs
+  section
+  title
+  sort
+  command
+  longtitle
+  icon
+  icon16x16
+  icon32x32
+  description
+  hotkey
+  hints
+);
+
+# These 'needs' tags are always valid, no matter the context, and no other
+# values are valid outside the Window Managers context (don't include wm here,
+# in other words).  It's case insensitive, use lower case here.
+my @needs_tag_vals = qw(x11 text vc);
+
+has MENU_SECTIONS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %menu_sections;
+
+        my $data = $self->data->load('menu-format/menu-sections');
+
+        for my $key ($data->all) {
+
+            my ($root, $under) = split(m{/}, $key, 2);
+
+            $under //= $EMPTY;
+
+            # $under is empty if this is just a root section
+            $menu_sections{$root}{$under} = 1;
+        }
+
+        return \%menu_sections;
+    }
+);
+
+# Authoritative source of desktop keys:
+# https://specifications.freedesktop.org/desktop-entry-spec/latest/
+#
+# This is a list of all keys that should be in every desktop entry.
+my @req_desktop_keys = qw(Type Name);
+
+# This is a list of all known keys.
+has KNOWN_DESKTOP_KEYS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->load('menu-format/known-desktop-keys');
+    }
+);
+
+has DEPRECATED_DESKTOP_KEYS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->load('menu-format/deprecated-desktop-keys');
+    }
+);
+
+# KDE uses some additional keys that should start with X-KDE but don't for
+# historical reasons.
+has KDE_DESKTOP_KEYS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->load('menu-format/kde-desktop-keys');
+    }
+);
+
+# Known types of desktop entries.
+# https://specifications.freedesktop.org/desktop-entry-spec/latest/ar01s06.html
+my %known_desktop_types = map { $_ => 1 } qw(
+  Application
+  Link
+  Directory
+);
+
+# Authoritative source of desktop categories:
+# https://specifications.freedesktop.org/menu-spec/latest/apa.html
+
+# This is a list of all Main Categories for .desktop files.  Application is
+# added as an exception; it's not listed in the standard, but it's widely used
+# and used as an example in the GNOME documentation.  GNUstep is added as an
+# exception since it's used by GNUstep packages.
+my %main_categories = map { $_ => 1 } qw(
+  AudioVideo
+  Audio
+  Video
+  Development
+  Education
+  Game
+  Graphics
+  Network
+  Office
+  Science
+  Settings
+  System
+  Utility
+  Application
+  GNUstep
+);
+
+# This is a list of all Additional Categories for .desktop files.  Ideally we
+# should be checking to be sure the associated Main Categories are present,
+# but we don't have support for that yet.
+has ADD_CATEGORIES => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->data->load('menu-format/add-categories');
+    }
+);
+
+# This is a list of Reserved Categories for .desktop files.  To use one of
+# these, the desktop entry must also have an OnlyShowIn key limiting the
+# environment to one that supports this category.
+my %reserved_categories = map { $_ => 1 } qw(
+  Screensaver
+  TrayIcon
+  Applet
+  Shell
+);
+
+# Path in which to search for binaries referenced in menu entries.  These must
+# not have leading slashes.
+my @path = qw(usr/local/bin/ usr/bin/ bin/ usr/games/);
+
+my %known_tags_hash = map { $_ => 1 } @known_tags;
+my %needs_tag_vals_hash = map { $_ => 1 } @needs_tag_vals;
+
+# -----------------------------------
+
+sub installable {
+    my ($self) = @_;
+
+    my $index = $self->processable->installed;
+
+    my (@menufiles, %desktop_cmds);
+    for my $dirname (qw(usr/share/menu/ usr/lib/menu/)) {
+        if (my $dir = $index->resolve_path($dirname)) {
+            push(@menufiles, $dir->children);
+        }
+    }
+
+    # Find the desktop files in the package for verification.
+    my @desktop_files;
+    for my $subdir (qw(applications xsessions)) {
+        if (my $dir = $index->lookup("usr/share/$subdir/")) {
+            for my $item ($dir->children) {
+                next
+                  unless $item->is_file;
+
+                next
+                  if $item->is_dir;
+
+                next
+                  unless $item->basename =~ /\.desktop$/;
+
+                $self->pointed_hint('executable-desktop-file', $item->pointer,
+                    $item->octal_permissions)
+                  if $item->is_executable;
+
+                push(@desktop_files, $item)
+                  unless $item->name =~ / template /msx;
+            }
+        }
+    }
+
+    # Verify all the desktop files.
+    for my $desktop_file (@desktop_files) {
+        $self->verify_desktop_file($desktop_file, \%desktop_cmds);
+    }
+
+    # Now all the menu files.
+    for my $menufile (@menufiles) {
+        # Do not try to parse executables
+        next if $menufile->is_executable or not $menufile->is_open_ok;
+
+        # README is a special case
+        next if $menufile->basename eq 'README' && !$menufile->is_dir;
+        my $menufile_line =$EMPTY;
+
+        open(my $fd, '<', $menufile->unpacked_path)
+          or die encode_utf8('Cannot open ' . $menufile->unpacked_path);
+
+        # line below is commented out in favour of the while loop
+        # do { $_=<IN>; } while defined && (m/^\s* \#/ || m/^\s*$/);
+        while (my $line = <$fd>) {
+            if ($line =~ /^\s*\#/ || $line =~ /^\s*$/) {
+                next;
+
+            } else {
+                $menufile_line = $line;
+                last;
+            }
+        }
+
+        # Check first line of file to see if it matches the new menu
+        # file format.
+        if ($menufile_line =~ m/^!C\s*menu-2/) {
+            # we can't parse that yet
+            close($fd);
+            next;
+        }
+
+        # Parse entire file as a new format menu file.
+        my $line=$EMPTY;
+        my $lc=0;
+        do {
+            $lc++;
+
+            # Ignore lines that are comments.
+            if ($menufile_line =~ m/^\s*\#/) {
+                next;
+            }
+            $line .= $menufile_line;
+            # Note that I allow whitespace after the continuation character.
+            # This is caught by verify_line().
+            if (!($menufile_line =~ m/\\\s*?$/)) {
+                $self->verify_line($menufile, $line,$lc,\%desktop_cmds);
+                $line=$EMPTY;
+            }
+        } while ($menufile_line = <$fd>);
+        $self->verify_line($menufile, $line,$lc,\%desktop_cmds);
+
+        close($fd);
+    }
+
+    return;
+}
+
+# -----------------------------------
+
+# Pass this a line of a menu file, it sanitizes it and
+# verifies that it is correct.
+sub verify_line {
+    my ($self, $menufile, $line, $position,$desktop_cmds) = @_;
+
+    my $pointer = $menufile->pointer($position);
+    my %vals;
+
+    chomp $line;
+
+    # Replace all line continuation characters with whitespace.
+    # (do not remove them completely, because update-menus doesn't)
+    $line =~ s/\\\n/ /mg;
+
+    # This is in here to fix a common mistake: whitespace after a '\'
+    # character.
+    if ($line =~ s/\\\s+\n/ /mg) {
+        $self->pointed_hint('whitespace-after-continuation-character',
+            $pointer);
+    }
+
+    # Ignore lines that are all whitespace or empty.
+    return if $line =~ m/^\s*$/;
+
+    # Ignore lines that are comments.
+    return if $line =~ m/^\s*\#/;
+
+    # Start by testing the package check.
+    if (not $line =~ m/^\?package\((.*?)\):/) {
+        $self->pointed_hint('bad-test-in-menu-item', $pointer);
+        return;
+    }
+    my $pkg_test = $1;
+    my %tested_packages = map { $_ => 1 } split(/\s*,\s*/, $pkg_test);
+    my $tested_packages = scalar keys %tested_packages;
+    unless (exists $tested_packages{$self->processable->name}) {
+        $self->pointed_hint('pkg-not-in-package-test', $pointer, $pkg_test);
+    }
+    $line =~ s/^\?package\(.*?\)://;
+
+    # Now collect all the tag=value pairs. I've heavily commented
+    # the killer regexp that's responsible.
+    #
+    # The basic idea here is we start at the beginning of the line.
+    # Each loop pulls off one tag=value pair and advances to the next
+    # when we have no more matches, there should be no text left on
+    # the line - if there is, it's a parse error.
+    while (
+        $line =~ m{
+           \s*?                 # allow whitespace between pairs
+           (                    # capture what follows in $1, it's our tag
+            [^\"\s=]            # a non-quote, non-whitespace, character
+            *                   # match as many as we can
+           )
+           =
+           (                    # capture what follows in $2, it's our value
+            (?:
+             \"                 # this is a quoted string
+             (?:
+              \\.               # any quoted character
+              |                 # or
+              [^\"]             # a non-quote character
+             )
+             *                  # repeat as many times as possible
+             \"                 # end of the quoted value string
+            )
+            |                   # the other possibility is a non-quoted string
+            (?:
+             [^\"\s]            # a non-quote, non-whitespace character
+             *                  # match as many times as we can
+            )
+           )
+           }gcx
+    ) {
+        my $tag = $1;
+        my $value = $2;
+
+        if (exists $vals{$tag}) {
+            $self->pointed_hint('duplicate-tag-in-menu', $pointer, $1);
+        }
+
+        # If the value was quoted, remove those quotes.
+        if ($value =~ m/^\"(.*)\"$/) {
+            $value = $1;
+        } else {
+            $self->pointed_hint('unquoted-string-in-menu-item',$pointer, $1);
+        }
+
+        # If the value has escaped characters, remove the
+        # escapes.
+        $value =~ s/\\(.)/$1/g;
+
+        $vals{$tag} = $value;
+    }
+
+    # This is not really a no-op. Note the use of the /c
+    # switch - this makes perl keep track of the current
+    # search position. Notice, we did it above in the loop,
+    # too. (I have a /g here just so the /c takes affect.)
+    # We use this below when we look at how far along in the
+    # string we matched. So the point of this line is to allow
+    # trailing whitespace on the end of a line.
+    $line =~ m/\s*/gc;
+
+    # If that loop didn't match up to end of line, we have a
+    # problem..
+    if (pos($line) < length($line)) {
+        $self->pointed_hint('unparsable-menu-item', $pointer);
+        # Give up now, before things just blow up in our face.
+        return;
+    }
+
+    # Now validate the data in the menu file.
+
+    # Test for important tags.
+    for my $tag (@req_tags) {
+        unless (exists($vals{$tag}) && defined($vals{$tag})) {
+            $self->pointed_hint('menu-item-missing-required-tag',
+                $pointer, $tag);
+            # Just give up right away, if such an essential tag is missing,
+            # chance is high the rest doesn't make sense either. And now all
+            # following checks can assume those tags to be there
+            return;
+        }
+    }
+
+    # Make sure all tags are known.
+    for my $tag (keys %vals) {
+        if (!$known_tags_hash{$tag}) {
+            $self->pointed_hint('menu-item-contains-unknown-tag',
+                $pointer, $tag);
+        }
+    }
+
+    # Sanitize the section tag
+    my $section = $vals{'section'};
+    $section =~ tr:/:/:s;       # eliminate duplicate slashes. # Hallo emacs ;;
+    $section =~ s{/$}{}         # remove trailing slash
+      unless $section eq $SLASH; # - except if $section is '/'
+
+    # Be sure the command is provided by the package.
+    my ($okay, $command)
+      = $self->verify_cmd($pointer, $vals{'command'});
+
+    $self->pointed_hint('menu-command-not-in-package', $pointer, $command)
+      if !$okay
+      && length $command
+      && $tested_packages < 2
+      && $section !~ m{^(?:WindowManagers/Modules|FVWM Modules|Window Maker)};
+
+    if (length $command) {
+        $command =~ s{^(?:usr/)?s?bin/}{};
+        $command =~ s{^usr/games/}{};
+
+        $self->pointed_hint('command-in-menu-file-and-desktop-file',
+            $pointer, $command)
+          if $desktop_cmds->{$command};
+    }
+
+    $self->verify_icon('icon', $vals{'icon'},$MAXIMUM_SIZE_STANDARD_ICON,
+        $pointer);
+    $self->verify_icon('icon32x32', $vals{'icon32x32'},
+        $MAXIMUM_SIZE_32X32_ICON, $pointer);
+    $self->verify_icon('icon16x16', $vals{'icon16x16'},
+        $MAXIMUM_SIZE_16X16_ICON, $pointer);
+
+    # needs is case insensitive
+    my $needs = lc($vals{'needs'});
+
+    if ($section =~ m{^(WindowManagers/Modules|FVWM Modules|Window Maker)}) {
+        # WM/Modules: needs must not be the regular ones nor wm
+        $self->pointed_hint('non-wm-module-in-wm-modules-menu-section',
+            $pointer, $needs)
+          if $needs_tag_vals_hash{$needs} || $needs eq 'wm';
+
+    } elsif ($section =~ m{^Window ?Managers}) {
+        # Other WM sections: needs must be wm
+        $self->pointed_hint('non-wm-in-windowmanager-menu-section',
+            $pointer, $needs)
+          unless $needs eq 'wm';
+
+    } else {
+        # Any other section: just only the general ones
+        if ($needs eq 'dwww') {
+            $self->pointed_hint('menu-item-needs-dwww', $pointer);
+
+        } elsif (!$needs_tag_vals_hash{$needs}) {
+            $self->pointed_hint('menu-item-needs-tag-has-unknown-value',
+                $pointer, $needs);
+        }
+    }
+
+    # Check the section tag
+    # Check for historical changes in the section tree.
+    if ($section =~ m{^Apps/Games}) {
+        $self->pointed_hint('menu-item-uses-apps-games-section', $pointer);
+        $section =~ s{^Apps/}{};
+    }
+
+    if ($section =~ m{^Apps/}) {
+        $self->pointed_hint('menu-item-uses-apps-section', $pointer);
+        $section =~ s{^Apps/}{Applications/};
+    }
+
+    if ($section =~ m{^WindowManagers}) {
+        $self->pointed_hint('menu-item-uses-windowmanagers-section', $pointer);
+        $section =~ s{^WindowManagers}{Window Managers};
+    }
+
+    # Check for Evil new root sections.
+    my ($rootsec, $sect) = split(m{/}, $section, 2);
+
+    my $root_data = $self->MENU_SECTIONS->{$rootsec};
+
+    if (!defined $root_data) {
+
+        my $pkg = $self->processable->name;
+        $self->pointed_hint('menu-item-creates-new-root-section',
+            $pointer, $rootsec)
+          unless $rootsec =~ /$pkg/i;
+
+    } else {
+
+        $self->pointed_hint('menu-item-creates-new-section',
+            $pointer, $vals{section})
+          if (length $sect && !exists $root_data->{$sect})
+          || (!length $sect && !exists $root_data->{$EMPTY});
+    }
+
+    return;
+}
+
+sub verify_icon {
+    my ($self, $tag, $name, $size, $pointer)= @_;
+
+    return
+      unless length $name;
+
+    if ($name eq 'none') {
+
+        $self->pointed_hint('menu-item-uses-icon-none', $pointer, $tag);
+        return;
+    }
+
+    $self->pointed_hint('menu-icon-uses-relative-path', $pointer, $tag, $name)
+      unless $name =~ s{^/+}{};
+
+    if ($name !~ /\.xpm$/i) {
+
+        $self->pointed_hint('menu-icon-not-in-xpm-format',
+            $pointer, $tag, $name);
+        return;
+    }
+
+    my @packages = (
+        $self->processable,
+        @{ $self->group->direct_dependencies($self->processable) }
+    );
+
+    my @candidates;
+    for my $processable (@packages) {
+
+        push(@candidates, $processable->installed->resolve_path($name));
+        push(@candidates,
+            $processable->installed->resolve_path("usr/share/pixmaps/$name"));
+    }
+
+    my $iconfile = first_value { defined } @candidates;
+
+    if (!defined $iconfile || !$iconfile->is_open_ok) {
+
+        $self->pointed_hint('menu-icon-missing', $pointer, $tag, $name);
+        return;
+    }
+
+    open(my $fd, '<', $iconfile->unpacked_path)
+      or die encode_utf8('Cannot open ' . $iconfile->unpacked_path);
+
+    my $parse = 'XPM header';
+
+    my $line;
+    do { defined($line = <$fd>) or goto PARSE_ERROR; }
+      until ($line =~ /\/\*\s*XPM\s*\*\//);
+
+    $parse = 'size line';
+
+    do { defined($line = <$fd>) or goto PARSE_ERROR; }
+      until ($line =~ /"\s*([0-9]+)\s*([0-9]+)\s*(?:[0-9]+)\s*(?:[0-9]+)\s*"/);
+    my $width = $1 + 0;
+    my $height = $2 + 0;
+
+    if ($width > $size || $height > $size) {
+        $self->pointed_hint('menu-icon-too-big', $pointer, $tag,
+            "$name: ${width}x${height} > ${size}x${size}");
+    }
+
+    close($fd);
+
+    return;
+
+  PARSE_ERROR:
+    close($fd);
+    $self->pointed_hint('menu-icon-cannot-be-parsed', $pointer, $tag,
+        "$name: looking for $parse");
+
+    return;
+}
+
+# Syntax-checks a .desktop file.
+sub verify_desktop_file {
+    my ($self, $item, $desktop_cmds) = @_;
+
+    my ($saw_first, $warned_cr, %vals, @pending);
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        chomp $line;
+
+        my $pointer = $item->pointer($position);
+
+        next
+          if $line =~ /^\s*\#/ || $line =~ /^\s*$/;
+
+        if ($line =~ s/\r//) {
+            $self->pointed_hint('desktop-entry-file-has-crs', $pointer)
+              unless $warned_cr;
+            $warned_cr = 1;
+        }
+
+        # Err on the side of caution for now.  If the first non-comment line
+        # is not the required [Desktop Entry] group, ignore this file.  Also
+        # ignore any keys in other groups.
+        last
+          if $saw_first && $line =~ /^\[(.*)\]\s*$/;
+
+        unless ($saw_first) {
+            return
+              unless $line =~ /^\[(KDE )?Desktop Entry\]\s*$/;
+            $saw_first = 1;
+            $self->pointed_hint('desktop-contains-deprecated-key', $pointer)
+              if $line =~ /^\[KDE Desktop Entry\]\s*$/;
+        }
+
+        # Tag = Value.  For most errors, just add the error to pending rather
+        # than warning on it immediately since we want to not warn on tag
+        # errors if we didn't know the file type.
+        #
+        # TODO: We do not check for properly formatted localised values for
+        # keys but might be worth checking if they are properly formatted (not
+        # their value)
+        if ($line =~ /^(.*?)\s*=\s*(.*)$/) {
+            my ($tag, $value) = ($1, $2);
+            my $basetag = $tag;
+            $basetag =~ s/\[([^\]]+)\]$//;
+            if (exists $vals{$tag}) {
+                $self->pointed_hint('duplicate-key-in-desktop', $pointer,$tag);
+            } elsif ($self->DEPRECATED_DESKTOP_KEYS->recognizes($basetag)) {
+                if ($basetag eq 'Encoding') {
+                    push(@pending,
+                        ['desktop-entry-contains-encoding-key',$pointer, $tag]
+                    );
+                } else {
+                    push(
+                        @pending,
+                        [
+                            'desktop-entry-contains-deprecated-key',
+                            $pointer, $tag
+                        ]
+                    );
+                }
+            } elsif (not $self->KNOWN_DESKTOP_KEYS->recognizes($basetag)
+                and not $self->KDE_DESKTOP_KEYS->recognizes($basetag)
+                and not $basetag =~ /^X-/) {
+                push(@pending,
+                    ['desktop-entry-contains-unknown-key', $pointer, $tag]);
+            }
+            $vals{$tag} = $value;
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    close($fd);
+
+    # Now validate the data in the desktop file, but only if it's a known type.
+    # Warn if it's not.
+    my $type = $vals{'Type'};
+    return
+      unless defined $type;
+
+    unless ($known_desktop_types{$type}) {
+        $self->pointed_hint('desktop-entry-unknown-type', $item->pointer,
+            $type);
+        return;
+    }
+
+    $self->pointed_hint(@{$_}) for @pending;
+
+    # Test for important keys.
+    for my $tag (@req_desktop_keys) {
+        unless (defined $vals{$tag}) {
+            $self->pointed_hint('desktop-entry-missing-required-key',
+                $item->pointer, $tag);
+        }
+    }
+
+    # test if missing Keywords (only if NoDisplay is not set)
+    if (!defined $vals{NoDisplay}) {
+
+        $self->pointed_hint('desktop-entry-lacks-icon-entry', $item->pointer)
+          unless defined $vals{Icon};
+
+        $self->pointed_hint('desktop-entry-lacks-keywords-entry',
+            $item->pointer)
+          if !defined $vals{Keywords} && $vals{'Type'} eq 'Application';
+    }
+
+    # Only test whether the binary is in the package if the desktop file is
+    # directly under /usr/share/applications.  Too many applications use
+    # desktop files for other purposes with custom paths.
+    #
+    # TODO:  Should check quoting and the check special field
+    # codes in Exec for desktop files.
+    if (   $item->name =~ m{^usr/share/applications/}
+        && $vals{'Exec'}
+        && $vals{'Exec'} =~ /\S/) {
+
+        my ($okay, $command)
+          = $self->verify_cmd($item->pointer, $vals{'Exec'});
+
+        $self->pointed_hint('desktop-command-not-in-package',
+            $item->pointer, $command)
+          unless $okay
+          || $command eq 'kcmshell';
+
+        $command =~ s{^(?:usr/)?s?bin/}{};
+        $desktop_cmds->{$command} = 1
+          unless $command =~ m/^(?:su-to-root|sux?|(?:gk|kde)su)$/;
+    }
+
+    # Check the Category tag.
+    my $in_reserved;
+    if (defined $vals{'Categories'}) {
+
+        my $saw_main;
+
+        my @categories = split(/;/, $vals{'Categories'});
+        for my $category (@categories) {
+
+            next
+              if $category =~ /^X-/;
+
+            if ($reserved_categories{$category}) {
+                $self->pointed_hint('desktop-entry-uses-reserved-category',
+                    $item->pointer,$category)
+                  unless $vals{'OnlyShowIn'};
+
+                $saw_main = 1;
+                $in_reserved = 1;
+
+            } elsif (!$self->ADD_CATEGORIES->recognizes($category)
+                && !$main_categories{$category}) {
+                $self->pointed_hint('desktop-entry-invalid-category',
+                    $item->pointer, $category);
+
+            } elsif ($main_categories{$category}) {
+                $saw_main = 1;
+            }
+        }
+
+        $self->pointed_hint('desktop-entry-lacks-main-category',$item->pointer)
+          unless $saw_main;
+    }
+
+    # Check the OnlyShowIn tag.  If this is not an application in a reserved
+    # category, warn about any desktop entry that specifies OnlyShowIn for
+    # more than one environment.  In that case, the application probably
+    # should be using NotShowIn instead.
+    if (defined $vals{OnlyShowIn} and not $in_reserved) {
+        my @envs = split(/;/, $vals{OnlyShowIn});
+        if (@envs > 1) {
+            $self->pointed_hint('desktop-entry-limited-to-environments',
+                $item->pointer);
+        }
+    }
+
+    # Check that the Exec tag specifies how to pass a filename if MimeType
+    # tags are present.
+    if ($item->name =~ m{^usr/share/applications/}
+        && defined $vals{'MimeType'}) {
+
+        $self->pointed_hint('desktop-mime-but-no-exec-code', $item->pointer)
+          unless defined $vals{'Exec'}
+          && $vals{'Exec'} =~ /(?:^|[^%])%[fFuU]/;
+    }
+
+    return;
+}
+
+# Verify whether a command is shipped as part of the package.  Takes the full
+# path to the file being checked (for error reporting) and the binary.
+# Returns a list whose first member is true if the command is present and
+# false otherwise, and whose second member is the command (minus any leading
+# su-to-root wrapper).  Shared between the desktop and menu code.
+sub verify_cmd {
+    my ($self, $pointer, $exec) = @_;
+
+    my $index = $self->processable->installed;
+
+    # This routine handles su wrappers.  The option parsing here is ugly and
+    # dead-simple, but it's hopefully good enough for what will show up in
+    # desktop files.  su-to-root and sux require -c options, kdesu optionally
+    # allows one, and gksu has the command at the end of its arguments.
+    my @components = split($SPACE, $exec);
+    my $cmd;
+
+    $self->pointed_hint('su-to-root-with-usr-sbin', $pointer)
+      if $components[0] && $components[0] eq '/usr/sbin/su-to-root';
+
+    if (   $components[0]
+        && $components[0] =~ m{^(?:/usr/s?bin/)?(su-to-root|gksu|kdesu|sux)$}){
+
+        my $wrapper = $1;
+        shift @components;
+
+        while (@components) {
+            unless ($components[0]) {
+                shift @components;
+                next;
+            }
+
+            if ($components[0] eq '-c') {
+                $cmd = $components[1];
+                last;
+
+            } elsif (
+                $components[0] =~ /^-[Dfmupi]|^--(user|description|message)/) {
+                shift @components;
+                shift @components;
+
+            } elsif ($components[0] =~ /^-/) {
+                shift @components;
+
+            } else {
+                last;
+            }
+        }
+
+        if (!$cmd && $wrapper =~ /^(gk|kde)su$/) {
+            if (@components) {
+                $cmd = $components[0];
+            } else {
+                $cmd = $wrapper;
+                undef $wrapper;
+            }
+        }
+
+        $self->pointed_hint('su-wrapper-without--c', $pointer, $wrapper)
+          unless $cmd;
+
+        $self->pointed_hint('su-wrapper-not-su-to-root', $pointer, $wrapper)
+          if $wrapper
+          && $wrapper !~ /su-to-root/
+          && $wrapper ne $self->processable->name;
+
+    } else {
+        $cmd = $components[0];
+    }
+
+    my $cmd_file = $cmd;
+    if ($cmd_file) {
+        $cmd_file =~ s{^/}{};
+    }
+
+    my $okay = $cmd
+      && ( $cmd =~ /^[\'\"]/
+        || $index->lookup($cmd_file)
+        || $cmd =~ m{^(/bin/)?sh}
+        || $cmd =~ m{^(/usr/bin/)?sensible-(pager|editor|browser)}
+        || any { $index->lookup($_ . $cmd) } @path);
+
+    return ($okay, $cmd_file);
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Menus.pm b/lib/Lintian/Check/Menus.pm
new file mode 100644
index 0000000..2e8f3d1
--- /dev/null
+++ b/lib/Lintian/Check/Menus.pm
@@ -0,0 +1,818 @@
+# menus -- lintian check script -*- perl -*-
+
+# somewhat of a misnomer -- it doesn't only check menus
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2018 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Menus;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Spelling qw(check_spelling check_spelling_picky);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $DOT => q{.};
+const my $QUESTION_MARK => q{?};
+
+# Supported documentation formats for doc-base files.
+my %known_doc_base_formats
+  = map { $_ => 1 }qw(html text pdf postscript info dvi debiandoc-sgml);
+
+# Known fields for doc-base files.  The value is 1 for required fields and 0
+# for optional fields.
+my %KNOWN_DOCBASE_MAIN_FIELDS = (
+    'Document' => 1,
+    'Title'    => 1,
+    'Section'  => 1,
+    'Abstract' => 0,
+    'Author'   => 0
+);
+
+my %KNOWN_DOCBASE_FORMAT_FIELDS = (
+    'Format'  => 1,
+    'Files'   => 1,
+    'Index'   => 0
+);
+
+has menu_item => (is => 'rw');
+has menumethod_item => (is => 'rw');
+has documentation => (is => 'rw', default => 0);
+
+sub spelling_tag_emitter {
+    my ($self, @orig_args) = @_;
+
+    return sub {
+        return $self->pointed_hint(@orig_args, @_);
+    };
+}
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    if ($item->is_file) { # file checks
+         # menu file?
+        if ($item->name =~ m{^usr/(lib|share)/menu/\S}){ # correct permissions?
+
+            $self->pointed_hint('executable-menu-file', $item->pointer,
+                $item->octal_permissions)
+              if $item->is_executable;
+
+            return
+              if $item->name =~ m{^usr/(?:lib|share)/menu/README$};
+
+            if ($item->name =~ m{^usr/lib/}) {
+                $self->pointed_hint('menu-file-in-usr-lib', $item->pointer);
+            }
+
+            $self->menu_item($item);
+
+            $self->pointed_hint('bad-menu-file-name', $item->pointer)
+              if $item->name =~ m{^usr/(?:lib|share)/menu/menu$}
+              && $self->processable->name ne 'menu';
+        }
+        #menu-methods file?
+        elsif ($item->name =~ m{^etc/menu-methods/\S}) {
+            #TODO: we should test if the menu-methods file
+            # is made executable in the postinst as recommended by
+            # the menu manual
+
+            my $menumethod_includes_menu_h = 0;
+            $self->menumethod_item($item);
+
+            if ($item->is_open_ok) {
+                open(my $fd, '<', $item->unpacked_path)
+                  or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+                while (my $line = <$fd>) {
+                    chomp $line;
+                    if ($line =~ /^!include menu.h/) {
+                        $menumethod_includes_menu_h = 1;
+                        last;
+                    }
+                }
+                close($fd);
+            }
+
+            $self->pointed_hint('menu-method-lacks-include', $item->pointer)
+              unless $menumethod_includes_menu_h
+              or $self->processable->name eq 'menu';
+        }
+        # package doc dir?
+        elsif (
+            $item->name =~ m{ \A usr/share/doc/(?:[^/]+/)?
+                                 (.+\.(?:html|pdf))(?:\.gz)?
+                          \Z}xsm
+        ) {
+            my $name = $1;
+            unless ($name =~ m/^changelog\.html$/
+                or $name =~ m/^README[.-]/
+                or $name =~ m/examples/) {
+                $self->documentation(1);
+            }
+        }
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $pkg = $self->processable->name;
+    my $processable = $self->processable;
+    my $group = $self->group;
+
+    my (%all_files, %all_links);
+
+    my %preinst;
+    my %postinst;
+    my %prerm;
+    my %postrm;
+
+    $self->check_script($processable->control->lookup('preinst'),\%preinst);
+    $self->check_script($processable->control->lookup('postinst'),\%postinst);
+    $self->check_script($processable->control->lookup('prerm'),\%prerm);
+    $self->check_script($processable->control->lookup('postrm'),\%postrm);
+
+    # Populate all_{files,links} from current package and its dependencies
+    for my $installable ($group->get_installables) {
+        next
+          unless $processable->name eq $installable->name
+          || $processable->relation('strong')->satisfies($installable->name);
+
+        for my $item (@{$installable->installed->sorted_list}) {
+            add_file_link_info($installable, $item->name, \%all_files,
+                \%all_links);
+        }
+    }
+
+    # prerm scripts should not call update-menus
+    $self->pointed_hint('prerm-calls-updatemenus',$prerm{'calls-updatemenus'})
+      if defined $prerm{'calls-updatemenus'};
+
+    # postrm scripts should not call install-docs
+    $self->pointed_hint('postrm-calls-installdocs',
+        $postrm{'calls-installdocs'})
+      if defined $postrm{'calls-installdocs'};
+    $self->pointed_hint('postrm-calls-installdocs',
+        $postrm{'calls-installdocs-r'})
+      if defined $postrm{'calls-installdocs-r'};
+
+    # preinst scripts should not call either update-menus nor installdocs
+    $self->pointed_hint('preinst-calls-updatemenus',
+        $preinst{'calls-updatemenus'})
+      if defined $preinst{'calls-updatemenus'};
+
+    $self->pointed_hint('preinst-calls-installdocs',
+        $preinst{'calls-installdocs'})
+      if defined $preinst{'calls-installdocs'};
+
+    my $anymenu_item = $self->menu_item || $self->menumethod_item;
+
+    # No one needs to call install-docs any more; triggers now handles that.
+    $self->pointed_hint('postinst-has-useless-call-to-install-docs',
+        $postinst{'calls-installdocs'})
+      if defined $postinst{'calls-installdocs'};
+    $self->pointed_hint('postinst-has-useless-call-to-install-docs',
+        $postinst{'calls-installdocs-r'})
+      if defined $postinst{'calls-installdocs-r'};
+
+    $self->pointed_hint('prerm-has-useless-call-to-install-docs',
+        $prerm{'calls-installdocs'})
+      if defined $prerm{'calls-installdocs'};
+    $self->pointed_hint('prerm-has-useless-call-to-install-docs',
+        $prerm{'calls-installdocs-r'})
+      if defined $prerm{'calls-installdocs-r'};
+
+    # check consistency
+    # docbase file?
+    if (my $db_dir
+        = $processable->installed->resolve_path('usr/share/doc-base/')){
+        for my $item ($db_dir->children) {
+            next
+              if !$item->is_open_ok;
+
+            if ($item->resolve_path->is_executable) {
+
+                $self->pointed_hint('executable-in-usr-share-docbase',
+                    $item->pointer, $item->octal_permissions);
+                next;
+            }
+
+            $self->check_doc_base_file($item, \%all_files,\%all_links);
+        }
+    } elsif ($self->documentation) {
+        if ($pkg =~ /^libghc6?-.*-doc$/) {
+            # This is the library documentation for a haskell library. Haskell
+            # libraries register their documentation via the ghc compiler's
+            # documentation registration mechanism.  See bug #586877.
+        } else {
+            $self->hint('possible-documentation-but-no-doc-base-registration');
+        }
+    }
+
+    if ($anymenu_item) {
+        # postinst and postrm should not need to call update-menus
+        # unless there is a menu-method file.  However, update-menus
+        # currently won't enable packages that have outstanding
+        # triggers, leading to an update-menus call being required for
+        # at least some packages right now.  Until this bug is fixed,
+        # we still require it.  See #518919 for more information.
+        #
+        # That bug does not require calling update-menus from postrm,
+        # but debhelper apparently currently still adds that to the
+        # maintainer script, so don't warn if it's done.
+        $self->pointed_hint('postinst-does-not-call-updatemenus',
+            $anymenu_item->pointer)
+          if !defined $postinst{'calls-updatemenus'};
+
+        $self->pointed_hint(
+            'postrm-does-not-call-updatemenus',
+            $self->menumethod_item->pointer
+          )
+          if defined $self->menumethod_item
+          && !defined $postrm{'calls-updatemenus'}
+          && $pkg ne 'menu';
+
+    } else {
+        $self->pointed_hint('postinst-has-useless-call-to-update-menus',
+            $postinst{'calls-updatemenus'})
+          if defined $postinst{'calls-updatemenus'};
+
+        $self->pointed_hint('postrm-has-useless-call-to-update-menus',
+            $postrm{'calls-updatemenus'})
+          if defined $postrm{'calls-updatemenus'};
+    }
+
+    return;
+}
+
+# -----------------------------------
+
+sub check_doc_base_file {
+    my ($self, $item, $all_files, $all_links) = @_;
+
+    my $pkg = $self->processable->name;
+    my $group = $self->group;
+
+    # another check complains about invalid encoding
+    return
+      unless ($item->is_valid_utf8);
+
+    my $contents = $item->decoded_utf8;
+    my @lines = split(/\n/, $contents);
+
+    my $knownfields = \%KNOWN_DOCBASE_MAIN_FIELDS;
+    my ($field, @vals);
+    my %sawfields;        # local for each section of control file
+    my %sawformats;       # global for control file
+    my $line           = 0;  # global
+
+    my $position = 1;
+    while (defined(my $string = shift @lines)) {
+        chomp $string;
+
+        # New field.  check previous field, if we have any.
+        if ($string =~ /^(\S+)\s*:\s*(.*)$/) {
+            my (@new) = ($1, $2);
+            if ($field) {
+                $self->check_doc_base_field(
+                    $item, $line, $field,
+                    \@vals,\%sawfields, \%sawformats,
+                    $knownfields,$all_files, $all_links
+                );
+            }
+
+            $field = $new[0];
+
+            @vals  = ($new[1]);
+            $line  = $position;
+
+            # Continuation of previously defined field.
+        } elsif ($field && $string =~ /^\s+\S/) {
+            push(@vals, $string);
+
+            # All tags will be reported on the last continuation line of the
+            # doc-base field.
+            $line  = $position;
+
+            # Sections' separator.
+        } elsif ($string =~ /^(\s*)$/) {
+            $self->pointed_hint('doc-base-file-separator-extra-whitespace',
+                $item->pointer($position))
+              if $1;
+            next unless $field; # skip successive empty lines
+
+            # Check previously defined field and section.
+            $self->check_doc_base_field(
+                $item, $line, $field,
+                \@vals,\%sawfields, \%sawformats,
+                $knownfields,$all_files, $all_links
+            );
+            $self->check_doc_base_file_section($item, $line + 1,\%sawfields,
+                \%sawformats, $knownfields);
+
+            # Initialize variables for new section.
+            undef $field;
+            undef $line;
+            @vals      = ();
+            %sawfields = ();
+
+            # Each section except the first one is format section.
+            $knownfields = \%KNOWN_DOCBASE_FORMAT_FIELDS;
+
+            # Everything else is a syntax error.
+        } else {
+            $self->pointed_hint('doc-base-file-syntax-error',
+                $item->pointer($position));
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    # Check the last field/section of the control file.
+    if ($field) {
+        $self->check_doc_base_field(
+            $item, $line, $field,
+            \@vals, \%sawfields,\%sawformats,
+            $knownfields,$all_files,$all_links
+        );
+        $self->check_doc_base_file_section($item, $line, \%sawfields,
+            \%sawformats,$knownfields);
+    }
+
+    # Make sure we saw at least one format.
+    $self->pointed_hint('doc-base-file-no-format-section', $item->pointer)
+      unless %sawformats;
+
+    return;
+}
+
+# Checks one field of a doc-base control file.  $vals is array ref containing
+# all lines of the field.  Modifies $sawfields and $sawformats.
+sub check_doc_base_field {
+    my (
+        $self, $item, $position, $field,$vals,
+        $sawfields, $sawformats,$knownfields,$all_files, $all_links
+    ) = @_;
+
+    my $pkg = $self->processable->name;
+    my $group = $self->group;
+
+    my $SECTIONS = $self->data->load('doc-base/sections');
+
+    $self->pointed_hint('doc-base-file-unknown-field',
+        $item->pointer($position), $field)
+      unless defined $knownfields->{$field};
+    $self->pointed_hint('duplicate-field-in-doc-base',
+        $item->pointer($position), $field)
+      if $sawfields->{$field};
+    $sawfields->{$field} = 1;
+
+    # Index/Files field.
+    #
+    # Check if files referenced by doc-base are included in the package.  The
+    # Index field should refer to only one file without wildcards.  The Files
+    # field is a whitespace-separated list of files and may contain wildcards.
+    # We skip without validating wildcard patterns containing character
+    # classes since otherwise we'd need to deal with wildcards inside
+    # character classes and aren't there yet.
+    if ($field eq 'Index' or $field eq 'Files') {
+        my @files = map { split($SPACE) } @{$vals};
+
+        if ($field eq 'Index' && @files > 1) {
+            $self->pointed_hint('doc-base-index-references-multiple-files',
+                $item->pointer($position));
+        }
+        for my $file (@files) {
+            next if $file =~ m{^/usr/share/doc/};
+            next if $file =~ m{^/usr/share/info/};
+
+            $self->pointed_hint('doc-base-file-references-wrong-path',
+                $item->pointer($position), $file);
+        }
+        for my $file (@files) {
+            my $realfile = delink($file, $all_links);
+            # openoffice.org-dev-doc has thousands of files listed so try to
+            # use the hash if possible.
+            my $found;
+            if ($realfile =~ /[*?]/) {
+                my $regex = quotemeta($realfile);
+                unless ($field eq 'Index') {
+                    next if $regex =~ /\[/;
+                    $regex =~ s{\\\*}{[^/]*}g;
+                    $regex =~ s{\\\?}{[^/]}g;
+                    $regex .= $SLASH . $QUESTION_MARK;
+                }
+                $found = grep { /^$regex\z/ } keys %{$all_files};
+            } else {
+                $found = $all_files->{$realfile} || $all_files->{"$realfile/"};
+            }
+            unless ($found) {
+                $self->pointed_hint('doc-base-file-references-missing-file',
+                    $item->pointer($position),$file);
+            }
+        }
+        undef @files;
+
+        # Format field.
+    } elsif ($field eq 'Format') {
+        my $format = join($SPACE, @{$vals});
+
+        # trim both ends
+        $format =~ s/^\s+|\s+$//g;
+
+        $format = lc $format;
+        $self->pointed_hint('doc-base-file-unknown-format',
+            $item->pointer($position), $format)
+          unless $known_doc_base_formats{$format};
+        $self->pointed_hint('duplicate-format-in-doc-base',
+            $item->pointer($position), $format)
+          if $sawformats->{$format};
+        $sawformats->{$format} = 1;
+
+        # Save the current format for the later section check.
+        $sawformats->{' *current* '} = $format;
+
+        # Document field.
+    } elsif ($field eq 'Document') {
+        $_ = join($SPACE, @{$vals});
+
+        $self->pointed_hint('doc-base-invalid-document-field',
+            $item->pointer($position), $_)
+          unless /^[a-z0-9+.-]+$/;
+        $self->pointed_hint('doc-base-document-field-ends-in-whitespace',
+            $item->pointer($position))
+          if /[ \t]$/;
+        $self->pointed_hint('doc-base-document-field-not-in-first-line',
+            $item->pointer($position))
+          unless $position == 1;
+
+        # Title field.
+    } elsif ($field eq 'Title') {
+        if (@{$vals}) {
+            my $stag_emitter
+              = $self->spelling_tag_emitter(
+                'spelling-error-in-doc-base-title-field',
+                $item->pointer($position));
+            check_spelling(
+                $self->data,
+                join($SPACE, @{$vals}),
+                $group->spelling_exceptions,
+                $stag_emitter
+            );
+            check_spelling_picky($self->data, join($SPACE, @{$vals}),
+                $stag_emitter);
+        }
+
+        # Section field.
+    } elsif ($field eq 'Section') {
+        $_ = join($SPACE, @{$vals});
+        unless ($SECTIONS->recognizes($_)) {
+            if (m{^App(?:lication)?s/(.+)$} && $SECTIONS->recognizes($1)) {
+                $self->pointed_hint('doc-base-uses-applications-section',
+                    $item->pointer($position), $_);
+            } elsif (m{^(.+)/(?:[^/]+)$} && $SECTIONS->recognizes($1)) {
+                # allows creating a new subsection to a known section
+            } else {
+                $self->pointed_hint('doc-base-unknown-section',
+                    $item->pointer($position), $_);
+            }
+        }
+
+        # Abstract field.
+    } elsif ($field eq 'Abstract') {
+        # The three following variables are used for checking if the field is
+        # correctly phrased.  We detect if each line (except for the first
+        # line and lines containing single dot) of the field starts with the
+        # same number of spaces, not followed by the same non-space character,
+        # and the number of spaces is > 1.
+        #
+        # We try to match fields like this:
+        #  ||Abstract: The Boost web site provides free peer-reviewed portable
+        #  ||  C++ source libraries.  The emphasis is on libraries which work
+        #  ||  well with the C++ Standard Library.  One goal is to establish
+        #
+        # but not like this:
+        #  ||Abstract:  This is "Ding"
+        #  ||  * a dictionary lookup program for Unix,
+        #  ||  * DIctionary Nice Grep,
+        my $leadsp;            # string with leading spaces from second line
+        my $charafter;         # first non-whitespace char of second line
+        my $leadsp_ok = 1;     # are spaces OK?
+
+        # Intentionally skipping the first line.
+        for my $idx (1 .. $#{$vals}) {
+            $_ = $vals->[$idx];
+
+            if (/manage\s+online\s+manuals\s.*Debian/) {
+                $self->pointed_hint('doc-base-abstract-field-is-template',
+                    $item->pointer($position))
+                  unless $pkg eq 'doc-base';
+
+            } elsif (/^(\s+)\.(\s*)$/ and ($1 ne $SPACE or $2)) {
+                $self->pointed_hint(
+                    'doc-base-abstract-field-separator-extra-whitespace',
+                    $item->pointer($position - $#{$vals} + $idx)
+                );
+
+            } elsif (!$leadsp && /^(\s+)(\S)/) {
+                # The regexp should always match.
+                ($leadsp, $charafter) = ($1, $2);
+                $leadsp_ok = $leadsp eq $SPACE;
+
+            } elsif (!$leadsp_ok && /^(\s+)(\S)/) {
+                # The regexp should always match.
+                undef $charafter if $charafter && $charafter ne $2;
+                $leadsp_ok = 1
+                  if ($1 ne $leadsp) || ($1 eq $leadsp && $charafter);
+            }
+        }
+
+        unless ($leadsp_ok) {
+            $self->pointed_hint(
+                'doc-base-abstract-might-contain-extra-leading-whitespace',
+                $item->pointer($position));
+        }
+
+        # Check spelling.
+        if (@{$vals}) {
+            my $stag_emitter
+              = $self->spelling_tag_emitter(
+                'spelling-error-in-doc-base-abstract-field',
+                $item->pointer($position));
+            check_spelling(
+                $self->data,
+                join($SPACE, @{$vals}),
+                $group->spelling_exceptions,
+                $stag_emitter
+            );
+            check_spelling_picky($self->data, join($SPACE, @{$vals}),
+                $stag_emitter);
+        }
+    }
+
+    return;
+}
+
+# Checks the section of the doc-base control file.  Tries to find required
+# fields missing in the section.
+sub check_doc_base_file_section {
+    my ($self, $item, $position, $sawfields, $sawformats, $knownfields) = @_;
+
+    $self->pointed_hint('doc-base-file-no-format', $item->pointer($position))
+      if ((defined $sawfields->{'Files'} || defined $sawfields->{'Index'})
+        && !(defined $sawfields->{'Format'}));
+
+    # The current format is set by check_doc_base_field.
+    if ($sawfields->{'Format'}) {
+        my $format =  $sawformats->{' *current* '};
+        $self->pointed_hint('doc-base-file-no-index',$item->pointer($position))
+          if ( $format
+            && ($format eq 'html' || $format eq 'info')
+            && !$sawfields->{'Index'});
+    }
+    for my $field (sort keys %{$knownfields}) {
+        $self->pointed_hint('doc-base-file-lacks-required-field',
+            $item->pointer($position), $field)
+          if ($knownfields->{$field} == 1 && !$sawfields->{$field});
+    }
+
+    return;
+}
+
+# Add file and link to $all_files and $all_links.  Note that both files and
+# links have to include a leading /.
+sub add_file_link_info {
+    my ($processable, $file, $all_files, $all_links) = @_;
+
+    my $link = $processable->installed->lookup($file)->link;
+    my $ishard = $processable->installed->lookup($file)->is_hardlink;
+
+    # make name absolute
+    $file = $SLASH . $file
+      unless $file =~ m{^/};
+
+    $file =~ s{/+}{/}g;                           # remove duplicated `/'
+    $all_files->{$file} = 1;
+
+    if (length $link) {
+
+        $link = $DOT . $SLASH . $link
+          if $link !~ m{^/};
+
+        if ($ishard) {
+            $link =~ s{^\./}{/};
+        } elsif ($link !~ m{^/}) {            # not absolute link
+            $link
+              = $SLASH
+              . $link;                  # make sure link starts with '/'
+            $link =~ s{/+\./+}{/}g;                # remove all /./ parts
+            my $dcount = 1;
+            while ($link =~ s{^/+\.\./+}{/}) {     #\ count & remove
+                $dcount++;                         #/ any leading /../ parts
+            }
+            my $f = $file;
+            while ($dcount--) {                   #\ remove last $dcount
+                $f=~ s{/[^/]*$}{};                #/ path components from $file
+            }
+            $link
+              = $f. $link;                   # now we should have absolute link
+        }
+        $all_links->{$file} = $link unless ($link eq $file);
+    }
+
+    return;
+}
+
+# Dereference all symlinks in file.
+sub delink {
+    my ($file, $all_links) = @_;
+
+    $file =~ s{/+}{/}g;                            # remove duplicated '/'
+    return $file
+      unless %{$all_links};              # package doesn't symlinks
+
+    my $p1 = $EMPTY;
+    my $p2 = $file;
+    my %used_links;
+
+    # In the loop below we split $file into two parts on each '/' until
+    # there's no remaining slashes.  We try substituting the first part with
+    # corresponding symlink and if it succeeds, we start the procedure from
+    # beginning.
+    #
+    # Example:
+    #    Let $all_links{"/a/b"} == "/d", and $file == "/a/b/c"
+    #    Then 0) $p1 == "",     $p2 == "/a/b/c"
+    #         1) $p1 == "/a",   $p2 == "/b/c"
+    #         2) $p1 == "/a/b", $p2 == "/c"      ; substitute "/d" for "/a/b"
+    #         3) $p1 == "",     $p2 == "/d/c"
+    #         4) $p1 == "/d",   $p2 == "/c"
+    #         5) $p1 == "/d/c", $p2 == ""
+    #
+    # Note that the algorithm supposes, that
+    #    i) $all_links{$X} != $X for each $X
+    #   ii) both keys and values of %all_links start with '/'
+
+    while (($p2 =~ s{^(/[^/]*)}{}g) > 0) {
+        $p1 .= $1;
+        if (defined $all_links->{$p1}) {
+            return '!!! SYMLINK LOOP !!!' if defined $used_links{$p1};
+            $p2 = $all_links->{$p1} . $p2;
+            $p1 = $EMPTY;
+            $used_links{$p1} = 1;
+        }
+    }
+
+    # After the loop $p2 should be empty and $p1 should contain the target
+    # file.  In some rare cases when $file contains no slashes, $p1 will be
+    # empty and $p2 will contain the result (which will be equal to $file).
+    return $p1 ne $EMPTY ? $p1 : $p2;
+}
+
+sub check_script {
+    my ($self, $item, $pres) = @_;
+
+    my $pkg = $self->processable->name;
+
+    my ($no_check_menu, $no_check_installdocs);
+
+    # control files are regular files and not symlinks, pipes etc.
+    return
+      unless defined $item;
+
+    return
+      if $item->is_symlink;
+
+    return
+      unless $item->is_open_ok;
+
+    # nothing to do for ELF
+    return
+      if $item->is_elf;
+
+    my $interpreter = $item->interpreter || 'unknown';
+
+    if ($item->is_shell_script) {
+        $interpreter = 'sh';
+
+    } elsif ($interpreter =~ m{^/usr/bin/perl}) {
+        $interpreter = 'perl';
+    }
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+        # skip comments
+        $line =~ s/\#.*$//;
+
+        ##
+        # update-menus will satisfy the checks that the menu file
+        # installed is properly used
+        ##
+
+        # does the script check whether update-menus exists?
+        $pres->{'checks-for-updatemenus'} = $item->pointer($position)
+          if $line =~ /-x\s+\S*update-menus/
+          || $line =~ /(?:which|type)\s+update-menus/
+          || $line =~ /command\s+.*?update-menus/;
+
+        # does the script call update-menus?
+        # TODO this regex-magic should be moved to some lib for checking
+        # whether a certain word is likely called as command... --Jeroen
+        if (
+            $line =~m{ (?:^\s*|[;&|]\s*|(?:then|do|exec)\s+)
+               (?:\/usr\/bin\/)?update-menus
+               (?:\s|[;&|<>]|\Z)}xsm
+        ) {
+            # yes, it does.
+            $pres->{'calls-updatemenus'} = $item->pointer($position);
+
+            # checked first?
+            if (not $pres->{'checks-for-updatemenus'} and $pkg ne 'menu') {
+                $self->pointed_hint(
+'maintainer-script-does-not-check-for-existence-of-updatemenus',
+                    $item->pointer($position)
+                ) unless $no_check_menu++;
+            }
+        }
+
+        # does the script check whether install-docs exists?
+        $pres->{'checks-for-installdocs'} = $item->pointer($position)
+          if $line =~ s/-x\s+\S*install-docs//
+          || $line =~/(?:which|type)\s+install-docs/
+          || $line =~ s/command\s+.*?install-docs//;
+
+        # does the script call install-docs?
+        if (
+            $line =~ m{ (?:^\s*|[;&|]\s*|(?:then|do)\s+)
+               (?:\/usr\/sbin\/)?install-docs
+               (?:\s|[;&|<>]|\Z) }xsm
+        ) {
+            # yes, it does.  Does it remove or add a doc?
+            if ($line =~ /install-docs\s+(?:-r|--remove)\s/) {
+                $pres->{'calls-installdocs-r'} = $item->pointer($position);
+            } else {
+                $pres->{'calls-installdocs'} = $item->pointer($position);
+            }
+
+            # checked first?
+            if (not $pres->{'checks-for-installdocs'}) {
+                $self->pointed_hint(
+'maintainer-script-does-not-check-for-existence-of-installdocs',
+                    $item->pointer($position)
+                ) unless $no_check_installdocs++;
+            }
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    close($fd);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Mimeinfo.pm b/lib/Lintian/Check/Mimeinfo.pm
new file mode 100644
index 0000000..f24b73d
--- /dev/null
+++ b/lib/Lintian/Check/Mimeinfo.pm
@@ -0,0 +1,61 @@
+# mimeinfo -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Mimeinfo;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    if ($item->name =~ m{^usr/share/applications/mimeinfo.cache(?:\.gz)?$}){
+        $self->pointed_hint('package-contains-mimeinfo.cache-file',
+            $item->pointer);
+
+    }elsif ($item->name =~ m{^usr/share/mime/.+}) {
+
+        if ($item->name =~ m{^usr/share/mime/[^/]+$}) {
+            $self->pointed_hint('package-contains-mime-cache-file',
+                $item->pointer);
+
+        } elsif ($item->name !~ m{^usr/share/mime/packages/}) {
+            $self->pointed_hint(
+                'package-contains-mime-file-outside-package-dir',
+                $item->pointer);
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Modprobe.pm b/lib/Lintian/Check/Modprobe.pm
new file mode 100644
index 0000000..f9af6c7
--- /dev/null
+++ b/lib/Lintian/Check/Modprobe.pm
@@ -0,0 +1,61 @@
+# modprobe -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Modprobe;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(uniq);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    if (   $item->name =~ m{^etc/modprobe\.d/ }x
+        && $item->name !~ m{ [.]conf $}x
+        && !$item->is_dir) {
+
+        $self->pointed_hint('non-conf-file-in-modprobe.d', $item->pointer);
+
+    } elsif ($item->name =~ m{^ etc/modprobe[.]d/ }x
+        || $item->name =~ m{^ etc/modules-load\.d/ }x) {
+
+        my @obsolete = ($item->bytes =~ m{^ \s* ( install | remove ) }gmx);
+        $self->pointed_hint('obsolete-command-in-modprobe.d-file',
+            $item->pointer, $_)
+          for uniq @obsolete;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Nmu.pm b/lib/Lintian/Check/Nmu.pm
new file mode 100644
index 0000000..a758728
--- /dev/null
+++ b/lib/Lintian/Check/Nmu.pm
@@ -0,0 +1,193 @@
+# nmu -- lintian check script -*- perl -*-
+
+# Copyright (C) 2004 Jeroen van Wolffelaar
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Nmu;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any);
+use List::Util qw(first);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+sub source {
+    my ($self) = @_;
+
+    my $processable = $self->processable;
+
+    my $changelog_mentions_nmu = 0;
+    my $changelog_mentions_local = 0;
+    my $changelog_mentions_qa = 0;
+    my $changelog_mentions_team_upload = 0;
+
+    my $debian_dir = $processable->patched->resolve_path('debian/');
+
+    my $chf;
+    $chf = $debian_dir->child('changelog') if $debian_dir;
+
+    # This isn't really an NMU check, but right now no other check
+    # looks at debian/changelog in source packages.  Catch a
+    # debian/changelog file that's a symlink.
+    $self->pointed_hint('changelog-is-symlink', $chf->pointer)
+      if $chf && $chf->is_symlink;
+
+    return
+      unless $processable->changelog;
+
+    # Get some data from the changelog file.
+    my ($entry) = @{$processable->changelog->entries};
+
+    my $pointer = $chf->pointer($entry->position);
+
+    my $uploader = canonicalize($entry->Maintainer // $EMPTY);
+
+    # trim both ends
+    $self->pointed_hint('extra-whitespace-around-name-in-changelog-trailer',
+        $pointer)
+      if $uploader =~ s/^\s+|\s+$//g;
+
+    my $changes = $entry->Changes;
+    $changes =~ s/^(\s*\n)+//;
+    my $firstline = first { /^\s*\*/ } split(/\n/, $changes);
+
+    # Check the first line for QA, NMU or team upload mentions.
+    if ($firstline) {
+        local $_ = $firstline;
+        if (/\bnmu\b/i or /non-maintainer upload/i or m/LowThresholdNMU/i) {
+            unless (
+                m{
+                        (?:ackno|\back\b|confir|incorporat).*
+                        (?:\bnmu\b|non-maintainer)}xi
+            ) {
+                $changelog_mentions_nmu = 1;
+            }
+        }
+        $changelog_mentions_local = 1 if /\blocal\s+package\b/i;
+        $changelog_mentions_qa = 1 if /orphan/i or /qa (?:group )?upload/i;
+        $changelog_mentions_team_upload = 1 if /team upload/i;
+    }
+
+    # If the version field is missing, assume it to be a native,
+    # maintainer upload as it is probably the most likely case.
+    my $version = $processable->fields->value('Version') || '0-1';
+    my $maintainer= canonicalize($processable->fields->value('Maintainer'));
+    my $uploaders = $processable->fields->value('Uploaders');
+
+    my $version_nmuness = 0;
+    my $version_local = 0;
+    my $upload_is_backport = $version =~ m/~bpo(\d+)\+(\d+)$/;
+    my $upload_is_stable_update = $version =~ m/~deb(\d+)u(\d+)$/;
+
+    if ($version =~ /-[^.-]+(\.[^.-]+)?(\.[^.-]+)?$/) {
+        $version_nmuness = 1 if defined $1;
+        $version_nmuness = 2 if defined $2;
+    }
+    if ($version =~ /\+nmu\d+$/) {
+        $version_nmuness = 1;
+    }
+    if ($version =~ /\+b\d+$/) {
+        $version_nmuness = 2;
+    }
+    if ($version =~ /local/i) {
+        $version_local = 1;
+    }
+
+    my $upload_is_nmu = $uploader ne $maintainer;
+
+    my @uploaders = map { canonicalize($_) } split />\K\s*,\s*/,$uploaders;
+    $upload_is_nmu = 0 if any { $_ eq $uploader } @uploaders;
+
+    # If the changelog entry is missing a maintainer (eg. "-- <blank>")
+    # assume it's an upload still work in progress.
+    $upload_is_nmu = 0 if not $uploader;
+
+    if ($maintainer =~ /packages\@qa.debian.org/) {
+
+        $self->pointed_hint('uploaders-in-orphan', $pointer)
+          if $processable->fields->declares('Uploaders');
+
+        $self->pointed_hint('qa-upload-has-incorrect-version-number',
+            $pointer, $version)
+          if $version_nmuness == 1;
+
+        $self->pointed_hint('no-qa-in-changelog', $pointer)
+          unless $changelog_mentions_qa;
+
+    } elsif ($changelog_mentions_team_upload) {
+
+        $self->pointed_hint('team-upload-has-incorrect-version-number',
+            $pointer, $version)
+          if $version_nmuness == 1;
+
+        $self->pointed_hint('unnecessary-team-upload', $pointer)
+          unless $upload_is_nmu;
+
+    } else {
+        # Local packages may be either NMUs or not.
+        unless ($changelog_mentions_local || $version_local) {
+
+            $self->pointed_hint('no-nmu-in-changelog', $pointer)
+              if !$changelog_mentions_nmu && $upload_is_nmu;
+
+            $self->pointed_hint('source-nmu-has-incorrect-version-number',
+                $pointer, $version)
+              if $upload_is_nmu
+              && $version_nmuness != 1
+              && !$upload_is_stable_update
+              && !$upload_is_backport;
+        }
+
+        $self->pointed_hint('nmu-in-changelog', $pointer)
+          if $changelog_mentions_nmu && !$upload_is_nmu;
+
+        $self->pointed_hint('maintainer-upload-has-incorrect-version-number',
+            $pointer, $version)
+          if !$upload_is_nmu && $version_nmuness;
+    }
+
+    return;
+}
+
+# Canonicalize a maintainer address with respect to case.  E-mail addresses
+# are case-insensitive in the right-hand side.
+sub canonicalize {
+    my ($maintainer) = @_;
+
+    $maintainer =~ s/<([^>\@]+\@)([\w.-]+)>/<$1\L$2>/;
+
+    return $maintainer;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/ObsoleteSites.pm b/lib/Lintian/Check/ObsoleteSites.pm
new file mode 100644
index 0000000..976cdb2
--- /dev/null
+++ b/lib/Lintian/Check/ObsoleteSites.pm
@@ -0,0 +1,96 @@
+# obsolete-sites -- lintian check script -*- perl -*-
+
+# Copyright (C) 2015 Axel Beckert <abe@debian.org>
+# Copyright (C) 2017-2018 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::ObsoleteSites;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(any);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+my @interesting_files = qw(
+  control
+  copyright
+  watch
+  upstream
+  upstream/metadata
+  upstream-metadata.yaml
+);
+
+sub visit_patched_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_regular_file;
+
+    $self->search_for_obsolete_sites($item)
+      if any { $item->name =~ m{^ debian/$_ $}x } @interesting_files;
+
+    return;
+}
+
+sub search_for_obsolete_sites {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_open_ok;
+
+    my $OBSOLETE_SITES= $self->data->load('obsolete-sites/obsolete-sites');
+
+    my $bytes = $item->bytes;
+
+    # strip comments
+    $bytes =~ s/^ \s* [#] .* $//gmx;
+
+    for my $site ($OBSOLETE_SITES->all) {
+
+        if ($bytes
+            =~ m{ (\w+:// (?: [\w.]* [.] )? \Q$site\E [/:] [^\s"<>\$]* ) }ix) {
+
+            my $url = $1;
+            $self->pointed_hint('obsolete-url-in-packaging', $item->pointer,
+                $url);
+        }
+    }
+
+    if ($bytes =~ m{ (ftp:// (?:ftp|security) [.]debian[.]org) }ix) {
+
+        my $url = $1;
+        $self->pointed_hint('obsolete-url-in-packaging', $item->pointer, $url);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Origtar.pm b/lib/Lintian/Check/Origtar.pm
new file mode 100644
index 0000000..47de793
--- /dev/null
+++ b/lib/Lintian/Check/Origtar.pm
@@ -0,0 +1,55 @@
+# origtar -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2008 Bernhard R. Link
+# Copyright (C) 2019 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Origtar;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $processable = $self->processable;
+
+    return
+      if $processable->native;
+
+    my @origfiles = @{$processable->orig->sorted_list};
+
+    $self->hint('empty-upstream-sources')
+      unless @origfiles;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Pe.pm b/lib/Lintian/Check/Pe.pm
new file mode 100644
index 0000000..d5514d5
--- /dev/null
+++ b/lib/Lintian/Check/Pe.pm
@@ -0,0 +1,113 @@
+# pe -- lintian check script -*- perl -*-
+
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Pe;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Syntax::Keyword::Try;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SPACE => q{ };
+
+const my $MAIN_HEADER => 0x3c;
+const my $MAIN_HEADER_LENGTH_WORD_SIZE => 4;
+const my $OPTIONAL_HEADER => 0x18;
+const my $DLL_CHARACTERISTICS => 0x46;
+const my $ASLR_FLAG => 0x40;
+const my $DEP_NX_FLAG => 0x100;
+const my $UNSAFE_SEH_FLAG => 0x400;
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->file_type =~ /^PE32\+? executable/;
+
+    return
+      unless $item->is_open_ok;
+
+    my $buf;
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    try {
+        # offset to main header
+        seek($fd, $MAIN_HEADER, 0)
+          or die encode_utf8("seek: $!");
+
+        read($fd, $buf, $MAIN_HEADER_LENGTH_WORD_SIZE)
+          or die encode_utf8("read: $!");
+
+        my $pe_offset = unpack('V', $buf);
+
+        # 0x18 is index to "Optional Header"; 0x46 to DLL Characteristics
+        seek($fd, $pe_offset + $OPTIONAL_HEADER + $DLL_CHARACTERISTICS, 0)
+          or die encode_utf8("seek: $!");
+
+        # get DLLCharacteristics value
+        read($fd, $buf, 2)
+          or die encode_utf8("read: $!");
+
+    } catch {
+        die $@;
+    }
+
+    my $characteristics = unpack('v', $buf);
+    my %features = (
+        'ASLR' => $characteristics & $ASLR_FLAG,
+        'DEP/NX' => $characteristics & $DEP_NX_FLAG,
+        'SafeSEH' => ~$characteristics & $UNSAFE_SEH_FLAG,  # note negation
+    );
+
+    # Don't check for the x86-specific "SafeSEH" feature for code
+    # that is JIT-compiled by the Mono runtime. (#926334)
+    delete $features{'SafeSEH'}
+      if $item->file_type =~ / Mono\/.Net assembly, /;
+
+    my @missing = grep { !$features{$_} } sort keys %features;
+
+    $self->pointed_hint('portable-executable-missing-security-features',
+        $item->pointer,join($SPACE, @missing))
+      if scalar @missing;
+
+    close $fd;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Script/Deprecated/Chown.pm b/lib/Lintian/Check/Script/Deprecated/Chown.pm
new file mode 100644
index 0000000..e640e17
--- /dev/null
+++ b/lib/Lintian/Check/Script/Deprecated/Chown.pm
@@ -0,0 +1,96 @@
+# script/deprecated/chown -- lintian check script -*- perl -*-
+
+# Copyright (C) 2022 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Script::Deprecated::Chown;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Unicode::UTF8 qw(valid_utf8 encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub check_item {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->is_script;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        chomp $line;
+
+        next
+          if $line =~ /^#/;
+
+        next
+          unless length $line;
+
+        if ($line =~ m{ \b chown \s+ (?: -\S+ \s+ )* ( \S+ [.] \S+ ) \b }x) {
+
+            my $ownership = $1;
+
+            $self->pointed_hint('chown-with-dot', $item->pointer($position),
+                $ownership);
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    $self->check_item($item);
+
+    return;
+}
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    $self->check_item($item);
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Script/Syntax.pm b/lib/Lintian/Check/Script/Syntax.pm
new file mode 100644
index 0000000..20188f1
--- /dev/null
+++ b/lib/Lintian/Check/Script/Syntax.pm
@@ -0,0 +1,224 @@
+# script/syntax -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Script::Syntax;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use File::Basename;
+
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $MAXIMUM_LINES_ANALYZED => 54;
+
+# exclude some shells. zsh -n is broken, see #485885
+const my %SYNTAX_CHECKERS => (
+    sh => [qw{/bin/dash -n}],
+    bash => [qw{/bin/bash -n}]
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # Consider /usr/src/ scripts as "documentation"
+    # - packages containing /usr/src/ tend to be "-source" .debs
+    #   and usually come with overrides
+    # no checks necessary at all for scripts in /usr/share/doc/
+    # unless they are examples
+    return
+      if ($item->name =~ m{^usr/share/doc/} || $item->name =~ m{^usr/src/})
+      && $item->name !~ m{^usr/share/doc/[^/]+/examples/};
+
+    # Syntax-check most shell scripts, but don't syntax-check
+    # scripts that end in .dpatch.  bash -n doesn't stop checking
+    # at exit 0 and goes on to blow up on the patch itself.
+    $self->pointed_hint('shell-script-fails-syntax-check',$item->pointer)
+      if $self->fails_syntax_check($item)
+      && $item->name !~ m{^usr/share/doc/[^/]+/examples/}
+      && $item->name !~ /\.dpatch$/
+      && $item->name !~ /\.erb$/;
+
+    $self->pointed_hint('example-shell-script-fails-syntax-check',
+        $item->pointer)
+      if $self->fails_syntax_check($item)
+      && $item->name =~ m{^usr/share/doc/[^/]+/examples/}
+      && $item->name !~ /\.dpatch$/
+      && $item->name !~ /\.erb$/;
+
+    return;
+}
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    $self->pointed_hint('maintainer-shell-script-fails-syntax-check',
+        $item->pointer)
+      if $self->fails_syntax_check($item);
+
+    return;
+}
+
+sub fails_syntax_check {
+    my ($self, $item) = @_;
+
+    return 0
+      unless length $item->interpreter;
+
+    my $basename = basename($item->interpreter);
+
+    my @command;
+
+    # "Perl doesn't distinguish between restricted hashes and readonly hashes."
+    # https://metacpan.org/pod/Const::Fast#CAVEATS
+    @command = @{$SYNTAX_CHECKERS{$basename}}
+      if exists $SYNTAX_CHECKERS{$basename};
+
+    return 0
+      unless @command;
+
+    my $program = $command[0];
+    return 0
+      unless length $program
+      && -x $program;
+
+    return 0
+      unless $item->is_open_ok;
+
+    return 0
+      if script_looks_dangerous($item);
+
+  # Given an interpreter and a file, run the interpreter on that file with the
+  # -n option to check syntax, discarding output and returning the exit status.
+    safe_qx(@command, $item->unpacked_path);
+    my $failed = $?;
+
+    return $failed;
+}
+
+# Returns non-zero if the given file is not actually a shell script,
+# just looks like one.
+sub script_looks_dangerous {
+    my ($item) = @_;
+
+    my $result = 0;
+    my $shell_variable_name = '0';
+    my $backgrounded = 0;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        chomp $line;
+
+        next
+          if $line =~ /^#/;
+
+        next
+          unless length $line;
+
+        last
+          if $position >= $MAXIMUM_LINES_ANALYZED;
+
+        if (
+            $line =~ m<
+            # the exec should either be "eval"ed or a new statement
+            (?:^\s*|\beval\s*[\'\"]|(?:;|&&|\b(?:then|else))\s*)
+
+            # eat anything between the exec and $0
+            exec\s*.+\s*
+
+            # optionally quoted executable name (via $0)
+            .?\$$shell_variable_name.?\s*
+
+            # optional "end of options" indicator
+            (?:--\s*)?
+
+            # Match expressions of the form '${1+$@}', '${1:+"$@"',
+            # '"${1+$@', "$@", etc where the quotes (before the dollar
+            # sign(s)) are optional and the second (or only if the $1
+            # clause is omitted) parameter may be $@ or $*.
+            #
+            # Finally the whole subexpression may be omitted for scripts
+            # which do not pass on their parameters (i.e. after re-execing
+            # they take their parameters (and potentially data) from stdin
+            .?(?:\$[{]1:?\+.?)?(?:\$[\@\*])?>x
+        ) {
+            $result = 1;
+
+            last;
+
+        } elsif ($line =~ /^\s*(\w+)=\$0;/) {
+            $shell_variable_name = $1;
+
+        } elsif (
+            $line =~ m<
+            # Match scripts which use "foo $0 $@ &\nexec true\n"
+            # Program name
+            \S+\s+
+
+            # As above
+            .?\$$shell_variable_name.?\s*
+            (?:--\s*)?
+            .?(?:\$[{]1:?\+.?)?(?:\$[\@\*])?.?\s*\&>x
+        ) {
+
+            $backgrounded = 1;
+
+        } elsif (
+            $backgrounded
+            && $line =~ m{
+            # the exec should either be "eval"ed or a new statement
+            (?:^\s*|\beval\s*[\'\"]|(?:;|&&|\b(?:then|else))\s*)
+            exec\s+true(?:\s|\Z)}x
+        ) {
+
+            $result = 1;
+            last;
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return $result;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Scripts.pm b/lib/Lintian/Check/Scripts.pm
new file mode 100644
index 0000000..5539208
--- /dev/null
+++ b/lib/Lintian/Check/Scripts.pm
@@ -0,0 +1,1070 @@
+# scripts -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Scripts;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use File::Basename;
+use List::SomeUtils qw(any none);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::IPC::Run3 qw(safe_qx);
+use Lintian::Relation;
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $AT_SIGN => q{@};
+const my $ASTERISK => q{*};
+const my $DOT => q{.};
+const my $DOUBLE_QUOTE => q{"};
+const my $NOT_EQUAL => q{!=};
+
+const my $BAD_MAINTAINER_COMMAND_FIELDS => 5;
+const my $UNVERSIONED_INTERPRETER_FIELDS => 2;
+const my $VERSIONED_INTERPRETER_FIELDS => 5;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# This is a map of all known interpreters.  The key is the interpreter
+# name (the binary invoked on the #! line).  The value is an anonymous
+# array of two elements.  The first argument is the path on a Debian
+# system where that interpreter would be installed.  The second
+# argument is the dependency that provides that interpreter.
+#
+# $INTERPRETERS maps names of (unversioned) interpreters to the path
+# they are installed and what package to depend on to use them.
+#
+has INTERPRETERS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %unversioned;
+
+        my $data
+          = $self->data->load('scripts/interpreters',qr/ \s* => \s* /msx);
+
+        for my $interpreter ($data->all) {
+
+            my $remainder = $data->value($interpreter);
+
+            my ($folder, $prerequisites)= split(/ \s* , \s* /msx,
+                $remainder, $UNVERSIONED_INTERPRETER_FIELDS);
+
+            $prerequisites //= $EMPTY;
+
+            $unversioned{$interpreter} = {
+                folder => $folder,
+                prerequisites => $prerequisites
+            };
+        }
+
+        return \%unversioned;
+    }
+);
+
+# The more complex case of interpreters that may have a version number.
+#
+# This is a hash from the base interpreter name to a list.  The base
+# interpreter name may appear by itself or followed by some combination of
+# dashes, digits, and periods.
+#
+# The list contains the following values:
+#  [<path>, <dependency-relation>, <regex>, <dependency-template>, <version-list>]
+#
+# Their meaning is documented in Lintian's scripts/versioned-interpreters
+# file, though they are ordered differently and there are a few differences
+# as described below:
+#
+# * <regex> has been passed through qr/^<value>$/
+# * If <dependency-relation> was left out, it has been substituted by the
+#   interpreter.
+# * The magic values of <dependency-relation> are represented as:
+#   @SKIP_UNVERSIONED@ ->  undef (i.e the undefined value)
+# * <version-list> has been split into a list of versions.
+#   (e.g. "1.6 1.8" will be ["1.6", "1.8"])
+#
+# A full example is:
+#
+#    data:
+#        lua => /usr/bin, lua([\d.]+), 'lua$1', 40 50 5.1
+#
+#    $VERSIONED_INTERPRETERS->value ('lua') is
+#       [ '/usr/bin', 'lua', qr/^lua([\d.]+)$/, 'lua$1', ["40", "50", "5.1"] ]
+#
+has VERSIONED_INTERPRETERS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %versioned;
+
+        my $data = $self->data->load('scripts/versioned-interpreters',
+            qr/ \s* => \s* /msx);
+
+        for my $interpreter ($data->all) {
+
+            my $remainder = $data->value($interpreter);
+
+            my ($folder, $pattern, $template, $version_list, $prerequisites)
+              = split(/ \s* , \s* /msx,
+                $remainder, $VERSIONED_INTERPRETER_FIELDS);
+
+            my @versions = split(/ \s+ /msx, $version_list);
+            $prerequisites //= $EMPTY;
+
+            if ($prerequisites eq $AT_SIGN . 'SKIP_UNVERSIONED' . $AT_SIGN) {
+                $prerequisites = undef;
+
+            } elsif ($prerequisites =~ / @ /msx) {
+                die encode_utf8(
+"Unknown magic value $prerequisites for versioned interpreter $interpreter"
+                );
+            }
+
+            $versioned{$interpreter} = {
+                folder => $folder,
+                prerequisites => $prerequisites,
+                regex => qr/^$pattern$/,
+                template => $template,
+                versions => \@versions
+            };
+        }
+
+        return \%versioned;
+    }
+);
+
+# When detecting commands inside shell scripts, use this regex to match the
+# beginning of the command rather than checking whether the command is at the
+# beginning of a line.
+const my $LEADING_PATTERN=>
+'(?:(?:^|[`&;(|{])\s*|(?:if|then|do|while|!)\s+|env(?:\s+[[:alnum:]_]+=(?:\S+|\"[^"]*\"|\'[^\']*\'))*\s+)';
+const my $LEADING_REGEX => qr/$LEADING_PATTERN/;
+
+#forbidden command in maintainer scripts
+has BAD_MAINTAINER_COMMANDS => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %forbidden;
+
+        my $data = $self->data->load('scripts/maintainer-script-bad-command',
+            qr/\s*\~\~/);
+
+        for my $key ($data->all) {
+
+            my $value = $data->value($key);
+
+            my ($in_cat,$in_auto,$package_include_pattern,
+                $script_include_pattern,$command_pattern)
+              = split(/ \s* ~~ /msx, $value,$BAD_MAINTAINER_COMMAND_FIELDS);
+
+            die encode_utf8(
+                "Syntax error in scripts/maintainer-script-bad-command: $.")
+              if any { !defined }(
+                $in_cat,$in_auto,$package_include_pattern,
+                $script_include_pattern,$command_pattern
+              );
+
+            # trim both ends
+            $in_cat =~ s/^\s+|\s+$//g;
+            $in_auto =~ s/^\s+|\s+$//g;
+            $package_include_pattern =~ s/^\s+|\s+$//g;
+            $script_include_pattern =~ s/^\s+|\s+$//g;
+
+            $package_include_pattern ||= '\a\Z';
+
+            $script_include_pattern ||= $DOT . $ASTERISK;
+
+            $command_pattern=~ s/\$[{]LEADING_PATTERN[}]/$LEADING_PATTERN/;
+
+            $forbidden{$key} = {
+                ignore_automatic_sections => !!$in_auto,
+                in_cat_string => !!$in_cat,
+                package_exclude_regex => qr/$package_include_pattern/x,
+                script_include_regex => qr/$script_include_pattern/x,
+                command_pattern => $command_pattern,
+            };
+        }
+
+        return \%forbidden;
+    }
+);
+
+# Appearance of one of these regexes in a maintainer script means that there
+# must be a dependency (or pre-dependency) on the given package.  The tag
+# reported is maintainer-script-needs-depends-on-%s, so be sure to update
+# scripts.desc when adding a new rule.
+my %prerequisite_by_command_pattern = (
+    '\badduser\s' => 'adduser',
+    '\bgconf-schemas\s' => 'gconf2',
+    '\bupdate-inetd\s' =>
+'update-inetd | inet-superserver | openbsd-inetd | inetutils-inetd | rlinetd | xinetd',
+    '\bucf\s' => 'ucf',
+    '\bupdate-xmlcatalog\s' => 'xml-core',
+    '\bupdate-fonts-(?:alias|dir|scale)\s' => 'xfonts-utils',
+);
+
+# no dependency for install-menu, because the menu package specifically
+# says not to depend on it.
+has all_prerequisites => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $all_prerequisites
+          = $self->processable->relation('all')
+          ->logical_and($self->processable->relation('Provides'),
+            $self->processable->name);
+
+        return $all_prerequisites;
+    }
+);
+
+has strong_prerequisites => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $strong_prerequisites = $self->processable->relation('strong');
+
+        return $strong_prerequisites;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_script;
+
+    # Consider /usr/src/ scripts as "documentation"
+    # - packages containing /usr/src/ tend to be "-source" .debs
+    #   and usually comes with overrides for most of the checks
+    #   below.
+    # Supposedly, they could be checked as examples, but there is
+    # a risk that the scripts need substitution to be complete
+    # (so, syntax checking is not as reliable).
+
+    # no checks necessary at all for scripts in /usr/share/doc/
+    # unless they are examples
+    return
+      if ($item->name =~ m{^usr/share/doc/} || $item->name =~ m{^usr/src/})
+      && $item->name !~ m{^usr/share/doc/[^/]+/examples/};
+
+    my $basename = basename($item->interpreter);
+
+    # Ignore Python scripts that are shipped under dist-packages; these
+    # files aren't supposed to be called as scripts.
+    return
+      if $basename eq 'python'
+      && $item->name =~ m{^usr/lib/python3/dist-packages/};
+
+    # allow exception for .in files that have stuff like #!@PERL@
+    return
+      if $item->name =~ /\.in$/
+      && $item->interpreter =~ /^(\@|<\<)[A-Z_]+(\@|>\>)$/;
+
+    my $is_absolute = ($item->interpreter =~ m{^/} || $item->calls_env);
+
+    # As a special-exception, Policy 10.4 states that Perl scripts must use
+    # /usr/bin/perl directly and not via /usr/bin/env, etc.
+    $self->pointed_hint(
+        'incorrect-path-for-interpreter',
+        $item->pointer,'/usr/bin/env perl',
+        $NOT_EQUAL, '/usr/bin/perl'
+      )
+      if $item->calls_env
+      && $item->interpreter eq 'perl'
+      && $item->name !~ m{^usr/share/doc/[^/]+/examples/};
+
+    $self->pointed_hint(
+        'example-incorrect-path-for-interpreter',
+        $item->pointer,'/usr/bin/env perl',
+        $NOT_EQUAL, '/usr/bin/perl'
+      )
+      if $item->calls_env
+      && $item->interpreter eq 'perl'
+      && $item->name =~ m{^usr/share/doc/[^/]+/examples/};
+
+    # Skip files that have the #! line, but are not executable and
+    # do not have an absolute path and are not in a bin/ directory
+    # (/usr/bin, /bin etc).  They are probably not scripts after
+    # all.
+    return
+      if ( $item->name !~ m{(?:bin/|etc/init\.d/)}
+        && (!$item->is_file || !$item->is_executable)
+        && !$is_absolute
+        && $item->name !~ m{^usr/share/doc/[^/]+/examples/});
+
+    # Example directories sometimes contain Perl libraries, and
+    # some people use initial lines like #!perl or #!python to
+    # provide editor hints, so skip those too if they're not
+    # executable.  Be conservative here, since it's not uncommon
+    # for people to both not set examples executable and not fix
+    # the path and we want to warn about that.
+    return
+      if ( $item->name =~ /\.pm\z/
+        && (!$item->is_file || !$item->is_executable)
+        && !$is_absolute
+        && $item->name =~ m{^usr/share/doc/[^/]+/examples/});
+
+    # Skip upstream source code shipped in /usr/share/cargo/registry/
+    return
+      if $item->name =~ m{^usr/share/cargo/registry/};
+
+    if ($item->interpreter eq $EMPTY) {
+
+        $self->pointed_hint('script-without-interpreter', $item->pointer)
+          if $item->name !~ m{^usr/share/doc/[^/]+/examples/};
+
+        $self->pointed_hint('example-script-without-interpreter',
+            $item->pointer)
+          if $item->name =~ m{^usr/share/doc/[^/]+/examples/};
+
+        return;
+    }
+
+    # Either they use an absolute path or they use '/usr/bin/env interp'.
+    $self->pointed_hint('interpreter-not-absolute', $item->pointer,
+        $item->interpreter)
+      if !$is_absolute
+      && $item->name !~ m{^usr/share/doc/[^/]+/examples/};
+
+    $self->pointed_hint('example-interpreter-not-absolute',
+        $item->pointer,$item->interpreter)
+      if !$is_absolute
+      && $item->name =~ m{^usr/share/doc/[^/]+/examples/};
+
+    my $bash_completion_regex= qr{^usr/share/bash-completion/completions/.*};
+
+    $self->pointed_hint('script-not-executable', $item->pointer)
+      if (!$item->is_file || !$item->is_executable)
+      && $item->name !~ m{^usr/(?:lib|share)/.*\.pm}
+      && $item->name !~ m{^usr/(?:lib|share)/.*\.py}
+      && $item->name !~ m{^usr/(?:lib|share)/ruby/.*\.rb}
+      && $item->name !~ m{^usr/share/debconf/confmodule(?:\.sh)?$}
+      && $item->name !~ /\.in$/
+      && $item->name !~ /\.erb$/
+      && $item->name !~ /\.ex$/
+      && $item->name ne 'etc/init.d/skeleton'
+      && $item->name !~ m{^etc/menu-methods}
+      && $item->name !~ $bash_completion_regex
+      && $item->name !~ m{^etc/X11/Xsession\.d}
+      && $item->name !~ m{^usr/share/doc/}
+      && $item->name !~ m{^usr/src/};
+
+    return
+      unless $item->is_open_ok;
+
+    # Try to find the expected path of the script to check.  First
+    # check $INTERPRETERS and %versioned_interpreters.  If not
+    # found there, see if it ends in a version number and the base
+    # is found in $VERSIONED_INTERPRETERS
+    my $interpreter_data = $self->INTERPRETERS->{$basename};
+
+    my $versioned = 0;
+    unless (defined $interpreter_data) {
+
+        $interpreter_data = $self->VERSIONED_INTERPRETERS->{$basename};
+
+        if (!defined $interpreter_data && $basename =~ /^(.*[^\d.-])-?[\d.]+$/)
+        {
+            $interpreter_data = $self->VERSIONED_INTERPRETERS->{$1};
+            undef $interpreter_data
+              unless $interpreter_data
+              && $basename =~ /$interpreter_data->{regex}/;
+        }
+
+        $versioned = 1
+          if defined $interpreter_data;
+    }
+
+    if (defined $interpreter_data) {
+        my $expected = $interpreter_data->{folder} . $SLASH . $basename;
+
+        my @context = ($item->interpreter, $NOT_EQUAL, $expected);
+
+        $self->pointed_hint('wrong-path-for-interpreter', $item->pointer,
+            @context)
+          if $item->interpreter ne $expected
+          && !$item->calls_env
+          && $expected ne '/usr/bin/env perl'
+          && $item->name !~ m{^usr/share/doc/[^/]+/examples/};
+
+        $self->pointed_hint('example-wrong-path-for-interpreter',
+            $item->pointer, @context)
+          if $item->interpreter ne $expected
+          && !$item->calls_env
+          && $expected ne '/usr/bin/env perl'
+          && $item->name =~ m{^usr/share/doc/[^/]+/examples/};
+
+        $self->pointed_hint('incorrect-path-for-interpreter',
+            $item->pointer, @context)
+          if $item->interpreter ne $expected
+          && !$item->calls_env
+          && $expected eq '/usr/bin/env perl'
+          && $item->name !~ m{^usr/share/doc/[^/]+/examples/};
+
+        $self->pointed_hint('example-incorrect-path-for-interpreter',
+            $item->pointer, @context)
+          if $item->interpreter ne $expected
+          && !$item->calls_env
+          && $expected eq '/usr/bin/env perl'
+          && $item->name =~ m{^usr/share/doc/[^/]+/examples/};
+
+    } elsif ($item->interpreter =~ m{^/usr/local/}) {
+
+        $self->pointed_hint('interpreter-in-usr-local', $item->pointer,
+            $item->interpreter)
+          if $item->name !~ m{^usr/share/doc/[^/]+/examples/};
+
+        $self->pointed_hint('example-interpreter-in-usr-local',
+            $item->pointer,$item->interpreter)
+          if $item->name =~ m{^usr/share/doc/[^/]+/examples/};
+
+    } elsif ($item->interpreter eq '/bin/env') {
+
+        $self->pointed_hint('script-uses-bin-env', $item->pointer,
+            $item->interpreter)
+          if $item->name !~ m{^usr/share/doc/[^/]+/examples/};
+
+        $self->pointed_hint('example-script-uses-bin-env', $item->pointer,
+            $item->interpreter)
+          if $item->name =~ m{^usr/share/doc/[^/]+/examples/};
+
+    } elsif ($item->interpreter eq 'nodejs') {
+
+        $self->pointed_hint('script-uses-deprecated-nodejs-location',
+            $item->pointer,$item->interpreter)
+          if $item->name !~ m{^usr/share/doc/[^/]+/examples/};
+
+        $self->pointed_hint('example-script-uses-deprecated-nodejs-location',
+            $item->pointer,$item->interpreter)
+          if $item->name =~ m{^usr/share/doc/[^/]+/examples/};
+
+        # Check whether we have correct dependendies on nodejs regardless.
+        $interpreter_data = $self->INTERPRETERS->{'node'};
+
+    } elsif ($basename =~ /^php/) {
+
+        $self->pointed_hint('php-script-with-unusual-interpreter',
+            $item->pointer,$item->interpreter)
+          if $item->name !~ m{^usr/share/doc/[^/]+/examples/};
+
+        $self->pointed_hint('example-php-script-with-unusual-interpreter',
+            $item->pointer, $item->interpreter)
+          if $item->name =~ m{^usr/share/doc/[^/]+/examples/};
+
+        # This allows us to still perform the dependencies checks
+        # below even when an unusual interpreter has been found.
+        $interpreter_data = $self->INTERPRETERS->{'php'};
+
+    } else {
+        my @private_interpreters;
+
+        # Check if the package ships the interpreter (and it is
+        # executable).
+        my $name = $item->interpreter;
+        if ($name =~ s{^/}{}) {
+            my $file = $self->processable->installed->lookup($name);
+            push(@private_interpreters, $file)
+              if defined $file;
+
+        } elsif ($item->calls_env) {
+            my @files= map {
+                $self->processable->installed->lookup(
+                    $_ . $SLASH . $item->interpreter)
+            }qw{bin usr/bin};
+            push(@private_interpreters, grep { defined } @files);
+        }
+
+        $self->pointed_hint('unusual-interpreter', $item->pointer,
+            $item->interpreter)
+          if (none { $_->is_file && $_->is_executable } @private_interpreters)
+          && $item->name !~ m{^usr/share/doc/[^/]+/examples/};
+
+        $self->pointed_hint('example-unusual-interpreter', $item->pointer,
+            $item->interpreter)
+          if (none { $_->is_file && $_->is_executable } @private_interpreters)
+          && $item->name =~ m{^usr/share/doc/[^/]+/examples/};
+    }
+
+    # If we found the interpreter and the script is executable,
+    # check dependencies.  This should be the last thing we do in
+    # the loop so that we can use next for an early exit and
+    # reduce the nesting.
+    return
+      unless $interpreter_data;
+
+    return
+      unless $item->is_file && $item->is_executable;
+
+    return
+      if $item->name =~ m{^usr/share/doc/} || $item->name =~ m{^usr/src/};
+
+    if (!$versioned) {
+        my $depends = $interpreter_data->{prerequisites};
+
+        if ($depends && !$self->all_prerequisites->satisfies($depends)) {
+
+            if ($basename =~ /^php/) {
+
+                $self->pointed_hint('php-script-but-no-php-cli-dep',
+                    $item->pointer, $item->interpreter,
+                    "(does not satisfy $depends)");
+
+            } elsif ($basename =~ /^(python\d|ruby|[mg]awk)$/) {
+
+                $self->pointed_hint(
+                    (
+                        "$basename-script-but-no-$basename-dep",
+                        $item->pointer,
+                        $item->interpreter,
+                        "(does not satisfy $depends)"
+                    )
+                );
+
+            } elsif ($basename eq 'csh'
+                && $item->name =~ m{^etc/csh/login\.d/}){
+                # Initialization files for csh.
+
+            } elsif ($basename eq 'fish' && $item->name =~ m{^etc/fish\.d/}) {
+                # Initialization files for fish.
+
+            } elsif (
+                $basename eq 'ocamlrun'
+                && $self->all_prerequisites->matches(
+                    qr/^ocaml(?:-base)?(?:-nox)?-\d\.[\d.]+/)
+            ) {
+                # ABI-versioned virtual packages for ocaml
+
+            } elsif ($basename eq 'escript'
+                && $self->all_prerequisites->matches(qr/^erlang-abi-[\d+\.]+$/)
+            ) {
+                # ABI-versioned virtual packages for erlang
+
+            } else {
+
+                $self->pointed_hint('missing-dep-for-interpreter',
+                    $item->pointer, $item->interpreter,
+                    "(does not satisfy $depends)");
+            }
+        }
+
+    } elsif (exists $self->VERSIONED_INTERPRETERS->{$basename}) {
+        my @versions = @{ $interpreter_data->{versions} };
+
+        my @depends;
+        for my $version (@versions) {
+            my $d = $interpreter_data->{template};
+            $d =~ s/\$1/$version/g;
+            push(@depends, $d);
+        }
+
+        unshift(@depends, $interpreter_data->{prerequisites})
+          if length $interpreter_data->{prerequisites};
+
+        my $depends = join(' | ',  @depends);
+        unless ($self->all_prerequisites->satisfies($depends)) {
+            if ($basename =~ /^(wish|tclsh)/) {
+
+                my $shell_name = $1;
+
+                $self->pointed_hint(
+                    "$shell_name-script-but-no-$shell_name-dep",
+                    $item->pointer, $item->interpreter,
+                    "(does not satisfy $depends)");
+
+            } else {
+
+                $self->pointed_hint('missing-dep-for-interpreter',
+                    $item->pointer, $item->interpreter,
+                    "(does not satisfy $depends)");
+            }
+        }
+
+    } else {
+
+        my ($version) = ($basename =~ /$interpreter_data->{regex}/);
+        my $depends = $interpreter_data->{template};
+        $depends =~ s/\$1/$version/g;
+
+        unless ($self->all_prerequisites->satisfies($depends)) {
+            if ($basename =~ /^(python|ruby)/) {
+
+                $self->pointed_hint("$1-script-but-no-$1-dep",
+                    $item->pointer, $item->interpreter,
+                    "(does not satisfy $depends)");
+
+            } else {
+
+                $self->pointed_hint('missing-dep-for-interpreter',
+                    $item->pointer, $item->interpreter,
+                    "(does not satisfy $depends)");
+            }
+        }
+    }
+
+    return;
+}
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_maintainer_script;
+
+    if ($item->is_elf) {
+
+        $self->pointed_hint('elf-maintainer-script', $item->pointer);
+        return;
+    }
+
+    # keep 'env', if present
+    my $interpreter = $item->hashbang;
+
+    # keep base command without options
+    $interpreter =~ s/^(\S+).*/$1/;
+
+    if ($interpreter eq $EMPTY) {
+
+        $self->pointed_hint('script-without-interpreter', $item->pointer);
+        return;
+    }
+
+    # tag for statistics
+    $self->pointed_hint('maintainer-script-interpreter',
+        $item->pointer, $interpreter);
+
+    $self->pointed_hint('interpreter-not-absolute', $item->pointer,
+        $interpreter)
+      unless $interpreter =~ m{^/};
+
+    my $basename = basename($interpreter);
+
+    if ($interpreter =~ m{^/usr/local/}) {
+        $self->pointed_hint('control-interpreter-in-usr-local',
+            $item->pointer, $interpreter);
+
+    } elsif ($basename eq 'sh' || $basename eq 'bash' || $basename eq 'perl') {
+        my $expected
+          = $self->INTERPRETERS->{$basename}->{folder}. $SLASH. $basename;
+
+        my $tag_name
+          = ($expected eq '/usr/bin/env perl')
+          ?
+          'incorrect-path-for-interpreter'
+          : 'wrong-path-for-interpreter';
+
+        $self->pointed_hint(
+            $tag_name, $item->pointer,  $interpreter,
+            $NOT_EQUAL, $expected
+        )unless $interpreter eq $expected;
+
+    } elsif ($item->name eq 'config') {
+        $self->pointed_hint('forbidden-config-interpreter',
+            $item->pointer, $interpreter);
+
+    } elsif ($item->name eq 'postrm') {
+        $self->pointed_hint('forbidden-postrm-interpreter',
+            $item->pointer, $interpreter);
+
+    } elsif (exists $self->INTERPRETERS->{$basename}) {
+
+        my $interpreter_data = $self->INTERPRETERS->{$basename};
+        my $expected = $interpreter_data->{folder} . $SLASH . $basename;
+
+        my $tag_name
+          = ($expected eq '/usr/bin/env perl')
+          ?
+          'incorrect-path-for-interpreter'
+          : 'wrong-path-for-interpreter';
+
+        $self->pointed_hint(
+            $tag_name, $item->pointer, $interpreter,
+            $NOT_EQUAL, $expected
+        )unless $interpreter eq $expected;
+
+        $self->pointed_hint('unusual-control-interpreter', $item->pointer,
+            $interpreter);
+
+        # Interpreters used by preinst scripts must be in
+        # Pre-Depends.  Interpreters used by postinst or prerm
+        # scripts must be in Depends.
+        if ($interpreter_data->{prerequisites}) {
+
+            my $depends = Lintian::Relation->new->load(
+                $interpreter_data->{prerequisites});
+
+            if ($item->name eq 'preinst') {
+
+                $self->pointed_hint(
+                    'control-interpreter-without-predepends',
+                    $item->pointer,
+                    $interpreter,
+                    '(does not satisfy ' . $depends->to_string . ')'
+                  )
+                  unless $self->processable->relation('Pre-Depends')
+                  ->satisfies($depends);
+
+            } else {
+
+                $self->pointed_hint(
+                    'control-interpreter-without-depends',
+                    $item->pointer,
+                    $interpreter,
+                    '(does not satisfy ' . $depends->to_string . ')'
+                  )
+                  unless $self->processable->relation('strong')
+                  ->satisfies($depends);
+            }
+        }
+
+    } else {
+        $self->pointed_hint('unknown-control-interpreter', $item->pointer,
+            $interpreter);
+
+        # no use doing further checks if it's not a known interpreter
+        return;
+    }
+
+    return
+      unless $item->is_open_ok;
+
+    # now scan the file contents themselves
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $saw_debconf;
+    my $saw_bange;
+    my $saw_sete;
+    my $saw_udevadm_guard;
+
+    my $cat_string = $EMPTY;
+
+    my $previous_line = $EMPTY;
+    my $in_automatic_section = 0;
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        my $pointer = $item->pointer($position);
+
+        $saw_bange = 1
+          if $position == 1
+          && $item->is_shell_script
+          && $line =~ m{/$basename\s*.*\s-\w*e\w*\b};
+
+        $in_automatic_section = 1
+          if $line =~ /^# Automatically added by \S+\s*$/;
+
+        $in_automatic_section = 0
+          if $line eq '# End automatically added section';
+
+        # skip empty lines
+        next
+          if $line =~ /^\s*$/;
+
+        # skip comment lines
+        next
+          if $line =~ /^\s*\#/;
+
+        $line = remove_comments($line);
+
+        # Concatenate lines containing continuation character (\)
+        # at the end
+        if ($item->is_shell_script && $line =~ /\\$/) {
+
+            $line =~ s/\\//;
+            chomp $line;
+            $previous_line .= $line;
+
+            next;
+        }
+
+        chomp $line;
+
+        $line = $previous_line . $line;
+        $previous_line = $EMPTY;
+
+        $saw_sete = 1
+          if $item->is_shell_script
+          && $line =~ /${LEADING_REGEX}set\s*(?:\s+-(?:-.*|[^e]+))*\s-\w*e/;
+
+        $saw_udevadm_guard = 1
+          if $line =~ /\b(if|which|command)\s+.*udevadm/g;
+
+        if ($line =~ m{$LEADING_REGEX(?:/bin/)?udevadm\s} && $saw_sete) {
+
+            $self->pointed_hint('udevadm-called-without-guard',$pointer)
+              unless $saw_udevadm_guard
+              || $line =~ m{\|\|}
+              || $self->strong_prerequisites->satisfies('udev:any');
+        }
+
+        if ($item->is_shell_script) {
+
+            $cat_string = $EMPTY
+              if $cat_string ne $EMPTY
+              && $line =~ /^\Q$cat_string\E$/;
+
+            my $within_another_shell = 0;
+
+            $within_another_shell = 1
+              if $item->interpreter !~ m{(?:^|/)sh$}
+              && $item->interpreter_with_options =~ /\S+\s+-c/;
+
+            if (!$cat_string) {
+
+                $self->generic_check_bad_command($item, $line,
+                    $position, 0,$in_automatic_section);
+
+                $saw_debconf = 1
+                  if $line =~ m{/usr/share/debconf/confmodule};
+
+                $self->pointed_hint('read-in-maintainer-script',$pointer)
+                  if $line =~ /^\s*read(?:\s|\z)/ && !$saw_debconf;
+
+                $self->pointed_hint('multi-arch-same-package-calls-pycompile',
+                    $pointer)
+                  if $line =~ /^\s*py3?compile(?:\s|\z)/
+                  &&$self->processable->fields->value('Multi-Arch') eq 'same';
+
+                $self->pointed_hint('maintainer-script-modifies-inetd-conf',
+                    $pointer)
+                  if $line =~ m{>\s*/etc/inetd\.conf(?:\s|\Z)}
+                  && !$self->processable->relation('Provides')
+                  ->satisfies('inet-superserver:any');
+
+                $self->pointed_hint('maintainer-script-modifies-inetd-conf',
+                    $pointer)
+                  if $line=~ m{^\s*(?:cp|mv)\s+(?:.*\s)?/etc/inetd\.conf\s*$}
+                  && !$self->processable->relation('Provides')
+                  ->satisfies('inet-superserver:any');
+
+                # Check for running commands with a leading path.
+                #
+                # Unfortunately, our $LEADING_REGEX string doesn't work
+                # well for this in the presence of commands that
+                # contain backquoted expressions because it can't
+                # tell the difference between the initial backtick
+                # and the closing backtick.  We therefore first
+                # extract all backquoted expressions and check
+                # them separately, and then remove them from a
+                # copy of a string and then check it for bashisms.
+                while ($line =~ /\`([^\`]+)\`/g) {
+
+                    my $mangled = $1;
+
+                    if (
+                        $mangled =~ m{ $LEADING_REGEX
+                                      (/(?:usr/)?s?bin/[\w.+-]+)
+                                      (?:\s|;|\Z)}xsm
+                    ) {
+                        my $command = $1;
+
+                        $self->pointed_hint(
+                            'command-with-path-in-maintainer-script',
+                            $pointer, $command,'(in backticks)')
+                          unless $in_automatic_section;
+                    }
+                }
+
+                # check for test syntax
+                if(
+                    $line =~ m{\[\s+
+                          (?:!\s+)? -x \s+
+                          (/(?:usr/)?s?bin/[\w.+-]+)
+                          \s+ \]}xsm
+                ){
+                    my $command = $1;
+
+                    $self->pointed_hint(
+                        'command-with-path-in-maintainer-script',
+                        $pointer, $command,'(in test syntax)')
+                      unless $in_automatic_section;
+                }
+
+                my $mangled = $line;
+                $mangled =~ s/\`[^\`]+\`//g;
+
+                if ($mangled
+                    =~ m{$LEADING_REGEX(/(?:usr/)?s?bin/[\w.+-]+)(?:\s|;|$)}){
+                    my $command = $1;
+
+                    $self->pointed_hint(
+                        'command-with-path-in-maintainer-script',
+                        $pointer, $command, '(plain script)')
+                      unless $in_automatic_section;
+                }
+            }
+        }
+
+        for my $pattern (keys %prerequisite_by_command_pattern) {
+
+            next
+              unless $line =~ /($pattern)/;
+
+            my $command = $1;
+
+            next
+              if $line =~ /-x\s+\S*$pattern/
+              || $line =~ /(?:which|type)\s+$pattern/
+              || $line =~ /command\s+.*?$pattern/
+              || $line =~ m{ [|][|] \s* true \b }x;
+
+            my $requirement = $prerequisite_by_command_pattern{$pattern};
+
+            my $first_alternative = $requirement;
+            $first_alternative =~ s/[ \(].*//;
+
+            $self->pointed_hint(
+                "maintainer-script-needs-depends-on-$first_alternative",
+                $pointer, $command,"(does not satisfy $requirement)")
+              unless $self->processable->relation('strong')
+              ->satisfies($requirement)
+              || $self->processable->name eq $first_alternative
+              || $item->name eq 'postrm';
+        }
+
+        $self->generic_check_bad_command($item, $line, $position, 1,
+            $in_automatic_section);
+
+        if ($line =~ m{$LEADING_REGEX(?:/usr/sbin/)?update-inetd\s}) {
+
+            $self->pointed_hint(
+                'maintainer-script-has-invalid-update-inetd-options',
+                $pointer, '(--pattern with --add)')
+              if $line =~ /--pattern/
+              && $line =~ /--add/;
+
+            $self->pointed_hint(
+                'maintainer-script-has-invalid-update-inetd-options',
+                $pointer, '(--group without --add)')
+              if $line =~ /--group/
+              && $line !~ /--add/;
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    $self->pointed_hint('maintainer-script-without-set-e', $item->pointer)
+      if $item->is_shell_script && !$saw_sete && $saw_bange;
+
+    $self->pointed_hint('maintainer-script-ignores-errors', $item->pointer)
+      if $item->is_shell_script && !$saw_sete && !$saw_bange;
+
+    return;
+}
+
+sub generic_check_bad_command {
+    my ($self, $script, $line, $position, $find_in_cat_string,
+        $in_automatic_section)
+      = @_;
+
+    for my $tag_name (keys %{$self->BAD_MAINTAINER_COMMANDS}) {
+
+        my $command_data= $self->BAD_MAINTAINER_COMMANDS->{$tag_name};
+
+        next
+          if $in_automatic_section
+          && $command_data->{ignore_automatic_sections};
+
+        next
+          unless $script->name =~ $command_data->{script_include_regex};
+
+        next
+          unless $find_in_cat_string == $command_data->{in_cat_string};
+
+        if ($line =~ m{ ( $command_data->{command_pattern} ) }x) {
+
+            my $bad_command = $1 // $EMPTY;
+
+            # trim both ends
+            $bad_command =~ s/^\s+|\s+$//g;
+
+            my $pointer = $script->pointer($position);
+
+            $self->pointed_hint($tag_name, $pointer,
+                $DOUBLE_QUOTE . $bad_command . $DOUBLE_QUOTE)
+              unless $self->processable->name
+              =~ $command_data->{package_exclude_regex};
+        }
+    }
+
+    return;
+}
+
+sub remove_comments {
+    my ($line) = @_;
+
+    return $line
+      unless length $line;
+
+    my $simplified = $line;
+
+    # Remove quoted strings so we can more easily ignore comments
+    # inside them
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\'(?:\\.|[^\\\'])+\'/$1''/g;
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\"(?:\\.|[^\\\"])+\"/$1""/g;
+
+    # If the remaining string contains what looks like a comment,
+    # eat it. In either case, swap the unmodified script line
+    # back in for processing (if required) and return it.
+    if ($simplified =~ m/(?:^|[^[\\])[\s\&;\(\)](\#.*$)/) {
+
+        my $comment = $1;
+
+        # eat comment
+        $line =~ s/\Q$comment\E//;
+    }
+
+    return $line;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Shell/Bash/Completion.pm b/lib/Lintian/Check/Shell/Bash/Completion.pm
new file mode 100644
index 0000000..4b0584e
--- /dev/null
+++ b/lib/Lintian/Check/Shell/Bash/Completion.pm
@@ -0,0 +1,54 @@
+# shell/bash/completion -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Shell::Bash::Completion;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->name =~ m{^ usr/share/bash-completion/completions/ }x;
+
+    $self->pointed_hint('bash-completion-with-hashbang',
+        $item->pointer(1), $item->hashbang)
+      if length $item->hashbang;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Shell/Csh.pm b/lib/Lintian/Check/Shell/Csh.pm
new file mode 100644
index 0000000..f84d374
--- /dev/null
+++ b/lib/Lintian/Check/Shell/Csh.pm
@@ -0,0 +1,89 @@
+# shell/csh -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Shell::Csh;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use File::Basename;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    # Consider /usr/src/ scripts as "documentation"
+    # - packages containing /usr/src/ tend to be "-source" .debs
+    #   and usually come with overrides
+    # no checks necessary at all for scripts in /usr/share/doc/
+    # unless they are examples
+    return
+      if ($item->name =~ m{^usr/share/doc/} || $item->name =~ m{^usr/src/})
+      && $item->name !~ m{^usr/share/doc/[^/]+/examples/};
+
+    $self->pointed_hint('csh-considered-harmful', $item->pointer(1),
+        $item->interpreter)
+      if $self->is_csh_script($item)
+      && $item->name !~ m{^ etc/csh/login[.]d/ }x;
+
+    return;
+}
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    # perhaps we should warn about *csh even if they're somehow screwed,
+    # but that's not really important...
+    $self->pointed_hint('csh-considered-harmful', $item->pointer(1),
+        $item->interpreter)
+      if $self->is_csh_script($item);
+
+    return;
+}
+
+sub is_csh_script {
+    my ($self, $item) = @_;
+
+    return 0
+      unless length $item->interpreter;
+
+    my $basename = basename($item->interpreter);
+
+    return 1
+      if $basename eq 'csh' || $basename eq 'tcsh';
+
+    return 0;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Shell/NonPosix/BashCentric.pm b/lib/Lintian/Check/Shell/NonPosix/BashCentric.pm
new file mode 100644
index 0000000..024ea6a
--- /dev/null
+++ b/lib/Lintian/Check/Shell/NonPosix/BashCentric.pm
@@ -0,0 +1,348 @@
+# shell/non-posix/bash-centric -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+# Copyright (C) 2021 Rafael Laboissiere
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+# bashism sounded too much like fascism
+package Lintian::Check::Shell::NonPosix::BashCentric;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use File::Basename;
+use List::SomeUtils qw(uniq);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+const my $SLASH => q{/};
+
+# When detecting commands inside shell scripts, use this regex to match the
+# beginning of the command rather than checking whether the command is at the
+# beginning of a line.
+const my $LEADING_PATTERN=>
+'(?:(?:^|[`&;(|{])\s*|(?:if|then|do|while|!)\s+|env(?:\s+[[:alnum:]_]+=(?:\S+|\"[^"]*\"|\'[^\']*\'))*\s+)';
+const my $LEADING_REGEX => qr/$LEADING_PATTERN/;
+
+my @bashism_single_quote_regexes = (
+    $LEADING_REGEX
+      . qr{echo\s+(?:-[^e\s]+\s+)?\'[^\']*(\\[abcEfnrtv0])+.*?[\']},
+    # unsafe echo with backslashes
+    $LEADING_REGEX . qr{source\s+[\"\']?(?:\.\/|[\/\$\w~.-])\S*},
+    # should be '.', not 'source'
+);
+
+my @bashism_string_regexes = (
+    qr/\$\[\w+\]/,                 # arith not allowed
+    qr/\$\{\w+\:\d+(?::\d+)?\}/,   # ${foo:3[:1]}
+    qr/\$\{\w+(\/.+?){1,2}\}/,     # ${parm/?/pat[/str]}
+    qr/\$\{\#?\w+\[[0-9\*\@]+\]\}/,# bash arrays, ${name[0|*|@]}
+    qr/\$\{!\w+[\@*]\}/,           # ${!prefix[*|@]}
+    qr/\$\{!\w+\}/,                # ${!name}
+    qr/(\$\(|\`)\s*\<\s*\S+\s*([\)\`])/, # $(\< foo) should be $(cat foo)
+    qr/\$\{?RANDOM\}?\b/,          # $RANDOM
+    qr/\$\{?(OS|MACH)TYPE\}?\b/,   # $(OS|MACH)TYPE
+    qr/\$\{?HOST(TYPE|NAME)\}?\b/, # $HOST(TYPE|NAME)
+    qr/\$\{?DIRSTACK\}?\b/,        # $DIRSTACK
+    qr/\$\{?EUID\}?\b/,            # $EUID should be "id -u"
+    qr/\$\{?UID\}?\b/,             # $UID should be "id -ru"
+    qr/\$\{?SECONDS\}?\b/,         # $SECONDS
+    qr/\$\{?BASH_[A-Z]+\}?\b/,     # $BASH_SOMETHING
+    qr/\$\{?SHELLOPTS\}?\b/,       # $SHELLOPTS
+    qr/\$\{?PIPESTATUS\}?\b/,      # $PIPESTATUS
+    qr/\$\{?SHLVL\}?\b/,           # $SHLVL
+    qr/<<</,                       # <<< here string
+    $LEADING_REGEX
+      . qr/echo\s+(?:-[^e\s]+\s+)?\"[^\"]*(\\[abcEfnrtv0])+.*?[\"]/,
+    # unsafe echo with backslashes
+);
+
+my @bashism_regexes = (
+    qr/(?:^|\s+)function \w+(\s|\(|\Z)/,  # function is useless
+    qr/(test|-o|-a)\s*[^\s]+\s+==\s/, # should be 'b = a'
+    qr/\[\s+[^\]]+\s+==\s/,        # should be 'b = a'
+    qr/\s(\|\&)/,                  # pipelining is not POSIX
+    qr/[^\\\$]\{(?:[^\s\\\}]*?,)+[^\\\}\s]*\}/, # brace expansion
+    qr/(?:^|\s+)\w+\[\d+\]=/,      # bash arrays, H[0]
+    $LEADING_REGEX . qr/read\s+(?:-[a-qs-zA-Z\d-]+)/,
+    # read with option other than -r
+    $LEADING_REGEX . qr/read\s*(?:-\w+\s*)*(?:\".*?\"|[\'].*?[\'])?\s*(?:;|$)/,
+    # read without variable
+    qr/\&>/,                       # cshism
+    qr/(<\&|>\&)\s*((-|\d+)[^\s;|)`&\\\\]|[^-\d\s]+)/, # should be >word 2>&1
+    qr/\[\[(?!:)/,                 # alternative test command
+    $LEADING_REGEX . qr/select\s+\w+/,    # 'select' is not POSIX
+    $LEADING_REGEX . qr/echo\s+(-n\s+)?-n?en?/,  # echo -e
+    $LEADING_REGEX . qr/exec\s+-[acl]/,   # exec -c/-l/-a name
+    qr/(?:^|\s+)let\s/,            # let ...
+    qr/(?<![\$\(])\(\(.*\)\)/,     # '((' should be '$(('
+    qr/\$\[[^][]+\]/,              # '$[' should be '$(('
+    qr/(\[|test)\s+-a/,            # test with unary -a (should be -e)
+    qr{/dev/(tcp|udp)},            # /dev/(tcp|udp)
+    $LEADING_REGEX . qr/\w+\+=/,   # should be "VAR="${VAR}foo"
+    $LEADING_REGEX . qr/suspend\s/,
+    $LEADING_REGEX . qr/caller\s/,
+    $LEADING_REGEX . qr/complete\s/,
+    $LEADING_REGEX . qr/compgen\s/,
+    $LEADING_REGEX . qr/declare\s/,
+    $LEADING_REGEX . qr/typeset\s/,
+    $LEADING_REGEX . qr/disown\s/,
+    $LEADING_REGEX . qr/builtin\s/,
+    $LEADING_REGEX . qr/set\s+-[BHT]+/,   # set -[BHT]
+    $LEADING_REGEX . qr/alias\s+-p/,      # alias -p
+    $LEADING_REGEX . qr/unalias\s+-a/,    # unalias -a
+    $LEADING_REGEX . qr/local\s+-[a-zA-Z]+/, # local -opt
+    qr/(?:^|\s+)\s*\(?\w*[^\(\w\s]+\S*?\s*\(\)\s*([\{|\(]|\Z)/,
+    # function names should only contain [a-z0-9_]
+    $LEADING_REGEX . qr/(push|pop)d(\s|\Z)/,   # (push|pod)d
+    $LEADING_REGEX . qr/export\s+-[^p]/,  # export only takes -p as an option
+    $LEADING_REGEX . qr/ulimit(\s|\Z)/,
+    $LEADING_REGEX . qr/shopt(\s|\Z)/,
+    $LEADING_REGEX . qr/time\s/,
+    $LEADING_REGEX . qr/dirs(\s|\Z)/,
+    qr/(?:^|\s+)[<>]\(.*?\)/,       # <() process substitution
+    qr/(?:^|\s+)readonly\s+-[af]/,  # readonly -[af]
+    $LEADING_REGEX . qr/(sh|\$\{?SHELL\}?) -[rD]/, # sh -[rD]
+    $LEADING_REGEX . qr/(sh|\$\{?SHELL\}?) --\w+/, # sh --long-option
+    $LEADING_REGEX . qr/(sh|\$\{?SHELL\}?) [-+]O/, # sh [-+]O
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless length $item->interpreter;
+
+    my $basename = basename($item->interpreter);
+
+    return
+      unless $basename eq 'sh';
+
+    $self->check_bash_centric($item, 'bash-term-in-posix-shell');
+
+    return;
+}
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless length $item->interpreter;
+
+    my $basename = basename($item->interpreter);
+
+    return
+      unless $basename eq 'sh';
+
+    $self->check_bash_centric($item, 'possible-bashism-in-maintainer-script');
+
+    return;
+}
+
+sub check_bash_centric {
+    my ($self, $item, $tag_name) = @_;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $stashed = $EMPTY;
+
+    my $position = 1;
+    while (my $possible_continuation = <$fd>) {
+
+        chomp $possible_continuation;
+
+        # skip empty lines
+        next
+          if $possible_continuation =~ /^\s*$/;
+
+        # skip comment lines
+        next
+          if $possible_continuation =~ /^\s*\#/;
+
+        my $no_comment = remove_comments($possible_continuation);
+
+        # Concatenate lines containing continuation character (\)
+        # at the end
+        if ($no_comment =~ s{\\$}{}) {
+
+            $stashed .= $no_comment;
+
+            next;
+        }
+
+        my $line = $stashed . $no_comment;
+        $stashed = $EMPTY;
+
+        # see Bug#999756 and tclsh(1)
+        last
+          if $line =~ m{^ exec \s }x;
+
+        my $pointer = $item->pointer($position);
+
+        my @matches = uniq +$self->check_line($line);
+
+        for my $match (@matches) {
+
+            my $printable = "'$match'";
+            $printable = '{hex:' . sprintf('%vX', $match) . '}'
+              if $match =~ /\P{XPosixPrint}/;
+
+            $self->pointed_hint($tag_name, $pointer, $printable);
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return;
+}
+
+sub check_line {
+    my ($self, $line) = @_;
+
+    my @matches;
+
+    # since this test is ugly, I have to do it by itself
+    # detect source (.) trying to pass args to the command it runs
+    # The first expression weeds out '. "foo bar"'
+    if (
+        $line !~  m{\A \s*\.\s+
+                                   (?:\"[^\"]+\"|\'[^\']+\')\s*
+                                   (?:[\&\|<;]|\d?>|\Z)}xsm
+        && $line =~ /^\s*(\.\s+[^\s;\`:]+\s+([^\s;]+))/
+    ) {
+
+        my ($dot_command, $extra) = ($1, $2);
+
+        push(@matches, $dot_command)
+          if length $dot_command
+          && $extra !~ m{^ & | [|] | < | \d? > }x;
+    }
+
+    my $modified = $line;
+
+    for my $regex (@bashism_single_quote_regexes) {
+        if ($modified =~ $regex) {
+
+            # on unmodified line
+            my ($match) = ($line =~ /($regex)/);
+
+            push(@matches, $match)
+              if length $match;
+        }
+    }
+
+    # Ignore anything inside single quotes; it could be an
+    # argument to grep or the like.
+
+    # Remove "quoted quotes". They're likely to be
+    # inside another pair of quotes; we're not
+    # interested in them for their own sake and
+    # removing them makes finding the limits of
+    # the outer pair far easier.
+    $modified =~ s/(^|[^\\\'\"])\"\'\"/$1/g;
+    $modified =~ s/(^|[^\\\'\"])\'\"\'/$1/g;
+
+    $modified =~ s/(^|[^\\\"](?:\\\\)*)\'(?:\\.|[^\\\'])+\'/$1''/g;
+
+    for my $regex (@bashism_string_regexes) {
+        if ($modified =~ $regex) {
+
+            # on unmodified line
+            my ($match) = ($line =~ /($regex)/);
+
+            $match //= $EMPTY;
+
+            push(@matches, $match)
+              if length $match;
+        }
+    }
+
+    $modified =~ s/(^|[^\\\'](?:\\\\)*)\"(?:\\.|[^\\\"])+\"/$1""/g;
+
+    for my $regex (@bashism_regexes) {
+        if ($modified =~ $regex) {
+
+            # on unmodified line
+            my ($match) = ($line =~ /($regex)/);
+
+            $match //= $EMPTY;
+
+            push(@matches, $match)
+              if length $match;
+        }
+    }
+
+    # trim both ends of each element
+    s/^\s+|\s+$//g for @matches;
+
+    my @meaningful = grep { length } @matches;
+
+    return @meaningful;
+}
+
+sub remove_comments {
+    my ($line) = @_;
+
+    return $line
+      unless length $line;
+
+    my $simplified = $line;
+
+    # Remove quoted strings so we can more easily ignore comments
+    # inside them
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\'(?:\\.|[^\\\'])+\'/$1''/g;
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\"(?:\\.|[^\\\"])+\"/$1""/g;
+
+    # If the remaining string contains what looks like a comment,
+    # eat it. In either case, swap the unmodified script line
+    # back in for processing (if required) and return it.
+    if ($simplified =~ m/(?:^|[^[\\])[\s\&;\(\)](\#.*$)/) {
+
+        my $comment = $1;
+
+        # eat comment
+        $line =~ s/\Q$comment\E//;
+    }
+
+    return $line;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Substvars/Libc.pm b/lib/Lintian/Check/Substvars/Libc.pm
new file mode 100644
index 0000000..db97ee5
--- /dev/null
+++ b/lib/Lintian/Check/Substvars/Libc.pm
@@ -0,0 +1,86 @@
+# substvars/libc -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Substvars::Libc;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Lintian::Relation;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# The list of libc packages, used for checking for a hard-coded dependency
+# rather than using ${shlibs:Depends}.
+const my @LIBCS => qw(libc6:any libc6.1:any libc0.1:any libc0.3:any);
+
+my $LIBC_RELATION = Lintian::Relation->new->load(join(' | ', @LIBCS));
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+
+    my @prerequisite_fields = qw(Pre-Depends Depends Recommends Suggests);
+
+    for my $installable ($control->installables) {
+        my $installable_fields = $control->installable_fields($installable);
+
+        for my $field (@prerequisite_fields) {
+
+            next
+              unless $control->installable_fields($installable)
+              ->declares($field);
+
+            my $relation
+              = $self->processable->binary_relation($installable,$field);
+
+            my $control_item= $self->processable->debian_control->item;
+            my $position = $installable_fields->position($field);
+            my $pointer = $control_item->pointer($position);
+
+            $self->pointed_hint(
+                'package-depends-on-hardcoded-libc',
+                $pointer,"(in section for $installable)",
+                $field, $relation->to_string
+              )
+              if $relation->satisfies($LIBC_RELATION)
+              && $self->processable->name !~ /^e?glibc$/;
+        }
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Substvars/Misc/PreDepends.pm b/lib/Lintian/Check/Substvars/Misc/PreDepends.pm
new file mode 100644
index 0000000..6172aca
--- /dev/null
+++ b/lib/Lintian/Check/Substvars/Misc/PreDepends.pm
@@ -0,0 +1,64 @@
+# substvars/misc/pre-depends -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Substvars::Misc::PreDepends;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $control = $self->processable->debian_control;
+
+    for my $installable ($control->installables) {
+        my $installable_fields = $control->installable_fields($installable);
+
+        my $field = 'Depends';
+
+        my $depends= $control->installable_fields($installable)->value($field);
+
+        my $control_item= $self->processable->debian_control->item;
+        my $position = $installable_fields->position($field);
+        my $pointer = $control_item->pointer($position);
+
+        $self->pointed_hint('depends-on-misc-pre-depends', $pointer,$depends,
+            "(in section for $installable)")
+          if $depends =~ m/\$\{misc:Pre-Depends\}/;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Systemd.pm b/lib/Lintian/Check/Systemd.pm
new file mode 100644
index 0000000..39487e0
--- /dev/null
+++ b/lib/Lintian/Check/Systemd.pm
@@ -0,0 +1,530 @@
+# systemd -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2013 Michael Stapelberg
+# Copyright (C) 2016-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# based on the apache2 checks file by:
+# Copyright (C) 2012 Arno Toell
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Systemd;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Data::Validate::URI qw(is_uri);
+use List::Compare;
+use List::SomeUtils qw(any none);
+use Text::ParseWords qw(shellwords);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+# "Usual" targets for WantedBy
+const my @WANTEDBY_WHITELIST => qw{
+  default.target
+  graphical.target
+  multi-user.target
+  network-online.target
+  sleep.target
+  sysinit.target
+};
+
+# Known hardening flags in [Service] section
+const my @HARDENING_FLAGS => qw{
+  CapabilityBoundingSet
+  DeviceAllow
+  DynamicUser
+  IPAddressDeny
+  InaccessiblePaths
+  KeyringMode
+  LimitNOFILE
+  LockPersonality
+  MemoryDenyWriteExecute
+  MountFlags
+  NoNewPrivileges
+  PrivateDevices
+  PrivateMounts
+  PrivateNetwork
+  PrivateTmp
+  PrivateUsers
+  ProtectControlGroups
+  ProtectHome
+  ProtectHostname
+  ProtectKernelLogs
+  ProtectKernelModules
+  ProtectKernelTunables
+  ProtectSystem
+  ReadOnlyPaths
+  RemoveIPC
+  RestrictAddressFamilies
+  RestrictNamespaces
+  RestrictRealtime
+  RestrictSUIDSGID
+  SystemCallArchitectures
+  SystemCallFilter
+  UMask
+};
+
+# init scripts that do not need a service file
+has PROVIDED_BY_SYSTEMD => (
+    is => 'rw',
+    lazy => 1,
+    default =>sub {
+        my ($self) = @_;
+
+        return $self->data->load('systemd/init-whitelist');
+    }
+);
+
+# array of names provided by the service files.
+# This includes Alias= directives, so after parsing
+# NetworkManager.service, it will contain NetworkManager and
+# network-manager.
+has service_names => (is => 'rw', default => sub { [] });
+
+has timer_files => (is => 'rw', default => sub { [] });
+
+has init_files_by_service_name => (is => 'rw', default => sub { {} });
+has cron_scripts => (is => 'rw', default => sub { [] });
+
+has is_rcs_script_by_name => (is => 'rw', default => sub { {} });
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    if ($item->name =~ m{/systemd/system/.*\.service$}) {
+
+        $self->check_systemd_service_file($item);
+
+        my $service_name = $item->basename;
+        $service_name =~ s/@?\.service$//;
+
+        push(@{$self->service_names}, $service_name);
+
+        my @aliases
+          = $self->extract_service_file_values($item, 'Install', 'Alias');
+
+        for my $alias (@aliases) {
+
+            $self->pointed_hint('systemd-service-alias-without-extension',
+                $item->pointer)
+              if $alias !~ m/\.service$/;
+
+            # maybe issue a tag for duplicates?
+
+            $alias =~ s{ [.]service $}{}x;
+            push(@{$self->service_names}, $alias);
+        }
+    }
+
+    push(@{$self->timer_files}, $item)
+      if $item->name =~ m{^(?:usr/)?lib/systemd/system/[^\/]+\.timer$};
+
+    push(@{$self->cron_scripts}, $item)
+      if $item->dirname =~ m{^ etc/cron[.][^\/]+ / $}x;
+
+    if (
+        $item->dirname eq 'etc/init.d/'
+        && !$item->is_dir
+        && (none { $item->basename eq $_} qw{README skeleton rc rcS})
+        && $self->processable->name ne 'initscripts'
+        && $item->link ne 'lib/init/upstart-job'
+    ) {
+
+        unless ($item->is_file) {
+
+            $self->pointed_hint('init-script-is-not-a-file', $item->pointer);
+            return;
+        }
+
+        # sysv generator drops the .sh suffix
+        my $service_name = $item->basename;
+        $service_name =~ s{ [.]sh $}{}x;
+
+        $self->init_files_by_service_name->{$service_name} //= [];
+        push(@{$self->init_files_by_service_name->{$service_name}}, $item);
+
+        $self->is_rcs_script_by_name->{$item->name}
+          = $self->check_init_script($item);
+    }
+
+    if ($item->name =~ m{ /systemd/system/ .*[.]socket $}x) {
+
+        my @values
+          = $self->extract_service_file_values($item,'Socket','ListenStream');
+
+        $self->pointed_hint('systemd-service-file-refers-to-var-run',
+            $item->pointer, 'ListenStream', $_)
+          for grep { m{^/var/run/} } @values;
+    }
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $lc = List::Compare->new([keys %{$self->init_files_by_service_name}],
+        $self->service_names);
+
+    my @missing_service_names = $lc->get_Lonly;
+
+    for my $service_name (@missing_service_names) {
+
+        next
+          if $self->PROVIDED_BY_SYSTEMD->recognizes($service_name);
+
+        my @init_files
+          = @{$self->init_files_by_service_name->{$service_name} // []};
+
+        for my $init_file (@init_files) {
+
+            # rcS scripts are particularly bad; always tag
+            $self->pointed_hint(
+                'missing-systemd-service-for-init.d-rcS-script',
+                $init_file->pointer, $service_name)
+              if $self->is_rcs_script_by_name->{$init_file->name};
+
+            $self->pointed_hint('omitted-systemd-service-for-init.d-script',
+                $init_file->pointer, $service_name)
+              if @{$self->service_names}
+              && !$self->is_rcs_script_by_name->{$init_file->name};
+
+            $self->pointed_hint('missing-systemd-service-for-init.d-script',
+                $init_file->pointer, $service_name)
+              if !@{$self->service_names}
+              && !$self->is_rcs_script_by_name->{$init_file->name};
+        }
+    }
+
+    if (!@{$self->timer_files}) {
+
+        $self->pointed_hint('missing-systemd-timer-for-cron-script',
+            $_->pointer)
+          for @{$self->cron_scripts};
+    }
+
+    return;
+}
+
+# Verify that each init script includes /lib/lsb/init-functions,
+# because that is where the systemd diversion happens.
+sub check_init_script {
+    my ($self, $item) = @_;
+
+    my $lsb_source_seen;
+    my $is_rcs_script = 0;
+
+    my @lines = split(/\n/, $item->decoded_utf8);
+
+    my $position = 1;
+    for my $line (@lines) {
+
+        # trim left
+        $line =~ s/^\s+//;
+
+        $lsb_source_seen = 1
+          if $position == 1
+          && $line
+          =~ m{\A [#]! \s* (?:/usr/bin/env)? \s* /lib/init/init-d-script}xsm;
+
+        $is_rcs_script = 1
+          if $line =~ m{#.*Default-Start:.*S};
+
+        next
+          if $line =~ /^#/;
+
+        $lsb_source_seen = 1
+          if $line
+          =~ m{(?:\.|source)\s+/lib/(?:lsb/init-functions|init/init-d-script)};
+
+    } continue {
+        ++$position;
+    }
+
+    $self->pointed_hint('init.d-script-does-not-source-init-functions',
+        $item->pointer)
+      unless $lsb_source_seen;
+
+    return $is_rcs_script;
+}
+
+sub check_systemd_service_file {
+    my ($self, $item) = @_;
+
+    # ambivalent about /lib or /usr/lib
+    $self->pointed_hint('systemd-service-in-odd-location', $item->pointer)
+      if $item =~ m{^etc/systemd/system/};
+
+    unless ($item->is_open_ok
+        || ($item->is_symlink && $item->link eq '/dev/null')) {
+
+        $self->pointed_hint('service-file-is-not-a-file', $item->pointer);
+        return 0;
+    }
+
+    my @values = $self->extract_service_file_values($item, 'Unit', 'After');
+    my @obsolete = grep { /^(?:syslog|dbus)\.target$/ } @values;
+
+    $self->pointed_hint('systemd-service-file-refers-to-obsolete-target',
+        $item->pointer, $_)
+      for @obsolete;
+
+    $self->pointed_hint('systemd-service-file-refers-to-obsolete-bindto',
+        $item->pointer)
+      if $self->extract_service_file_values($item, 'Unit', 'BindTo');
+
+    for my $key (
+        qw(ExecStart ExecStartPre ExecStartPost ExecReload ExecStop ExecStopPost)
+    ) {
+        $self->pointed_hint('systemd-service-file-wraps-init-script',
+            $item->pointer, $key)
+          if any { m{^/etc/init\.d/} }
+          $self->extract_service_file_values($item, 'Service', $key);
+    }
+
+    unless ($item->link eq '/dev/null') {
+
+        my @wanted_by
+          = $self->extract_service_file_values($item, 'Install', 'WantedBy');
+        my $is_oneshot = any { $_ eq 'oneshot' }
+          $self->extract_service_file_values($item, 'Service', 'Type');
+
+        # We are a "standalone" service file if we have no .path or .timer
+        # equivalent.
+        my $is_standalone = 1;
+        if ($item =~ m{^(usr/)?lib/systemd/system/([^/]*?)@?\.service$}) {
+
+            my ($usr, $service) = ($1 // $EMPTY, $2);
+
+            $is_standalone = 0
+              if $self->processable->installed->resolve_path(
+                "${usr}lib/systemd/system/${service}.path")
+              || $self->processable->installed->resolve_path(
+                "${usr}lib/systemd/system/${service}.timer");
+        }
+
+        for my $target (@wanted_by) {
+
+            $self->pointed_hint(
+                'systemd-service-file-refers-to-unusual-wantedby-target',
+                $item->pointer, $target)
+              unless (any { $target eq $_ } @WANTEDBY_WHITELIST)
+              || $self->processable->name eq 'systemd';
+        }
+
+        my @documentation
+          = $self->extract_service_file_values($item, 'Unit','Documentation');
+
+        $self->pointed_hint('systemd-service-file-missing-documentation-key',
+            $item->pointer)
+          unless @documentation;
+
+        for my $documentation (@documentation) {
+
+            my @uris = split(m{\s+}, $documentation);
+
+            my @invalid = grep { !is_uri($_) } @uris;
+
+            $self->pointed_hint('invalid-systemd-documentation',
+                $item->pointer, $_)
+              for @invalid;
+        }
+
+        my @kill_modes
+          = $self->extract_service_file_values($item, 'Service','KillMode');
+
+        for my $kill_mode (@kill_modes) {
+
+            # trim both ends
+            $kill_mode =~ s/^\s+|\s+$//g;
+
+            $self->pointed_hint('kill-mode-none',$item->pointer, $_)
+              if $kill_mode eq 'none';
+        }
+
+        if (   !@wanted_by
+            && !$is_oneshot
+            && $is_standalone
+            && $item =~ m{^(?:usr/)?lib/systemd/[^\/]+/[^\/]+\.service$}
+            && $item !~ m{@\.service$}) {
+
+            $self->pointed_hint('systemd-service-file-missing-install-key',
+                $item->pointer)
+              unless $self->extract_service_file_values($item, 'Install',
+                'RequiredBy')
+              || $self->extract_service_file_values($item, 'Install', 'Also');
+        }
+
+        my @pidfile
+          = $self->extract_service_file_values($item,'Service','PIDFile');
+        for my $x (@pidfile) {
+            $self->pointed_hint('systemd-service-file-refers-to-var-run',
+                $item->pointer, 'PIDFile', $x)
+              if $x =~ m{^/var/run/};
+        }
+
+        my $seen_hardening
+          = any { $self->extract_service_file_values($item, 'Service', $_) }
+          @HARDENING_FLAGS;
+
+        $self->pointed_hint('systemd-service-file-missing-hardening-features',
+            $item->pointer)
+          unless $seen_hardening
+          || $is_oneshot
+          || any { 'sleep.target' eq $_ } @wanted_by;
+
+        if (
+            $self->extract_service_file_values(
+                $item, 'Unit', 'DefaultDependencies', 1
+            )
+        ) {
+            my @before
+              = $self->extract_service_file_values($item, 'Unit','Before');
+            my @conflicts
+              = $self->extract_service_file_values($item, 'Unit','Conflicts');
+
+            $self->pointed_hint('systemd-service-file-shutdown-problems',
+                $item->pointer)
+              if (none { $_ eq 'shutdown.target' } @before)
+              && (any { $_ eq 'shutdown.target' } @conflicts);
+        }
+
+        my %bad_users = (
+            'User' => 'nobody',
+            'Group' => 'nogroup',
+        );
+
+        for my $key (keys %bad_users) {
+
+            my $value = $bad_users{$key};
+
+            $self->pointed_hint('systemd-service-file-uses-nobody-or-nogroup',
+                $item->pointer, "$key=$value")
+              if any { $_ eq $value }
+              $self->extract_service_file_values($item, 'Service',$key);
+        }
+
+        for my $key (qw(StandardError StandardOutput)) {
+            for my $value (qw(syslog syslog-console)) {
+
+                $self->pointed_hint(
+                    'systemd-service-file-uses-deprecated-syslog-facility',
+                    $item->pointer, "$key=$value")
+                  if any { $_ eq $value }
+                  $self->extract_service_file_values($item, 'Service',$key);
+            }
+        }
+    }
+
+    return 1;
+}
+
+sub service_file_lines {
+    my ($item) = @_;
+
+    my @output;
+
+    return @output
+      if $item->is_symlink and $item->link eq '/dev/null';
+
+    my @lines = split(/\n/, $item->decoded_utf8);
+    my $continuation = $EMPTY;
+
+    my $position = 1;
+    for my $line (@lines) {
+
+        $line = $continuation . $line;
+        $continuation = $EMPTY;
+
+        if ($line =~ s/\\$/ /) {
+            $continuation = $line;
+            next;
+        }
+
+        # trim right
+        $line =~ s/\s+$//;
+
+        next
+          unless length $line;
+
+        next
+          if $line =~ /^[#;\n]/;
+
+        push(@output, $line);
+    }
+
+    return @output;
+}
+
+# Extracts the values of a specific Key from a .service file
+sub extract_service_file_values {
+    my ($self, $item, $extract_section, $extract_key) = @_;
+
+    return ()
+      unless length $extract_section && length $extract_key;
+
+    my @values;
+    my $section;
+
+    my @lines = service_file_lines($item);
+    for my $line (@lines) {
+        # section header
+        if ($line =~ /^\[([^\]]+)\]$/) {
+            $section = $1;
+            next;
+        }
+
+        if (!defined($section)) {
+            # Assignment outside of section. Ignoring.
+            next;
+        }
+
+        my ($key, $value) = ($line =~ m{^(.*)\s*=\s*(.*)$});
+        if (   defined($key)
+            && $section eq $extract_section
+            && $key eq $extract_key) {
+
+            if (length $value) {
+                push(@values, shellwords($value));
+
+            } else {
+                # Empty assignment resets the list
+                @values = ();
+            }
+        }
+    }
+
+    return @values;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Systemd/Native/Prerequisites.pm b/lib/Lintian/Check/Systemd/Native/Prerequisites.pm
new file mode 100644
index 0000000..5a2480f
--- /dev/null
+++ b/lib/Lintian/Check/Systemd/Native/Prerequisites.pm
@@ -0,0 +1,146 @@
+# systemd/native/prerequisites -- lintian check script -*- perl -*-
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2002 Josip Rodin
+# Copyright (C) 2016-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Systemd::Native::Prerequisites;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(any none);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $EMPTY => q{};
+
+const my $SYSTEMD_NATIVE_PREREQUISITES => 'init-system-helpers:any';
+
+has satisfies_systemd_native_prerequisites => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $pre_depends = $self->processable->relation('Pre-Depends');
+
+        return $pre_depends->satisfies($SYSTEMD_NATIVE_PREREQUISITES);
+    }
+);
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_maintainer_script;
+
+    return
+      unless length $item->interpreter;
+
+    return
+      unless $item->is_open_ok;
+
+    open(my $fd, '<', $item->unpacked_path)
+      or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+    my $stashed = $EMPTY;
+
+    my $position = 1;
+    while (my $possible_continuation = <$fd>) {
+
+        chomp $possible_continuation;
+
+        # skip empty lines
+        next
+          if $possible_continuation =~ /^\s*$/;
+
+        # skip comment lines
+        next
+          if $possible_continuation =~ /^\s*\#/;
+
+        my $no_comment = remove_comments($possible_continuation);
+
+        # Concatenate lines containing continuation character (\)
+        # at the end
+        if ($no_comment =~ s{\\$}{}) {
+
+            $stashed .= $no_comment;
+
+            next;
+        }
+
+        my $line = $stashed . $no_comment;
+        $stashed = $EMPTY;
+
+        my $pointer = $item->pointer($position);
+
+        $self->pointed_hint('skip-systemd-native-flag-missing-pre-depends',
+            $pointer,"(does not satisfy $SYSTEMD_NATIVE_PREREQUISITES)")
+          if $line =~ /invoke-rc.d\b.*--skip-systemd-native\b/
+          && !$self->satisfies_systemd_native_prerequisites;
+
+    } continue {
+        ++$position;
+    }
+
+    return;
+}
+
+sub remove_comments {
+    my ($line) = @_;
+
+    return $line
+      unless length $line;
+
+    my $simplified = $line;
+
+    # Remove quoted strings so we can more easily ignore comments
+    # inside them
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\'(?:\\.|[^\\\'])+\'/$1''/g;
+    $simplified =~ s/(^|[^\\](?:\\\\)*)\"(?:\\.|[^\\\"])+\"/$1""/g;
+
+    # If the remaining string contains what looks like a comment,
+    # eat it. In either case, swap the unmodified script line
+    # back in for processing (if required) and return it.
+    if ($simplified =~ m/(?:^|[^[\\])[\s\&;\(\)](\#.*$)/) {
+
+        my $comment = $1;
+
+        # eat comment
+        $line =~ s/\Q$comment\E//;
+    }
+
+    return $line;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Systemd/Tmpfiles.pm b/lib/Lintian/Check/Systemd/Tmpfiles.pm
new file mode 100644
index 0000000..dc86628
--- /dev/null
+++ b/lib/Lintian/Check/Systemd/Tmpfiles.pm
@@ -0,0 +1,57 @@
+# systemd -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2013 Michael Stapelberg
+# Copyright (C) 2016-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# based on the apache2 checks file by:
+# Copyright (C) 2012 Arno Toell
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Systemd::Tmpfiles;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    $self->pointed_hint('systemd-tmpfile-in-var-run', $item->pointer)
+      if $item->name =~ m{^ usr/lib/tmpfiles[.]d/ .* [.]conf $}sx
+      && $item->decoded_utf8 =~ m{^ d \s+ /var/run/ }msx;
+
+    $self->pointed_hint('misplaced-systemd-tmpfiles', $item->pointer)
+      if $item->name =~ m{^ etc/tmpfiles[.]d/ .* [.]conf $}sx
+      && $item->is_file;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Team/PkgJs/Deprecated.pm b/lib/Lintian/Check/Team/PkgJs/Deprecated.pm
new file mode 100644
index 0000000..e04099d
--- /dev/null
+++ b/lib/Lintian/Check/Team/PkgJs/Deprecated.pm
@@ -0,0 +1,76 @@
+# team/pkg-js/deprecated -- lintian check script for deprecated javascript -*- perl -*-
+#
+# Copyright (C) 2019 Xavier Guimard <yadd@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Team::PkgJs::Deprecated;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has javascript_team_maintained => (
+    is => 'rw',
+    lazy => 1,
+    coerce => sub { my ($boolean) = @_; return ($boolean // 0); },
+    default => sub {
+        my ($self) = @_;
+
+        my $maintainer = $self->processable->fields->value('Maintainer');
+
+        # only for pkg-perl packages
+        return 1
+          if $maintainer
+          =~ /pkg-javascript-maintainers\@lists\.alioth\.debian\.org/;
+
+        return 0;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $self->javascript_team_maintained;
+
+    return
+      unless $item->name =~ /\.js$/;
+
+    my $bytes = $item->bytes;
+    return
+      unless length $bytes;
+
+    $self->pointed_hint('nodejs-bad-buffer-usage', $item->pointer)
+      if $bytes =~ /\bnew\s+Buffer\(/;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Team/PkgJs/Testsuite.pm b/lib/Lintian/Check/Team/PkgJs/Testsuite.pm
new file mode 100644
index 0000000..2920fe0
--- /dev/null
+++ b/lib/Lintian/Check/Team/PkgJs/Testsuite.pm
@@ -0,0 +1,73 @@
+# team/pkg-js/testsuite -- lintian check script for detecting a missing Testsuite header -*- perl -*-
+#
+# Copyright (C) 2013 Niels Thykier <niels@thykier.net>
+# Copyright (C) 2013 gregor herrmann <gregoa@debian.org>
+# Copyright (C) 2014 Niko Tyni <ntyni@debian.org>
+# Copyright (C) 2018 Florian Schlichting <fsfs@debian.org>
+# Copyright (C) 2019 Xavier Guimard <yadd@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Team::PkgJs::Testsuite;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(none);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $maintainer = $self->processable->fields->value('Maintainer');
+
+    # only for pkg-perl packages
+    return
+      unless $maintainer
+      =~ /pkg-javascript-maintainers\@lists\.alioth\.debian\.org/;
+
+    unless ($self->processable->fields->declares('Testsuite')) {
+
+        $self->hint('no-testsuite-header');
+        return;
+    }
+
+    my @testsuites
+      = $self->processable->fields->trimmed_list('Testsuite', qr/,/);
+
+    if (none { $_ eq 'autopkgtest-pkg-perl' } @testsuites) {
+
+        $self->hint('no-team-tests');
+        return;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Team/PkgJs/Vcs.pm b/lib/Lintian/Check/Team/PkgJs/Vcs.pm
new file mode 100644
index 0000000..e4d4bec
--- /dev/null
+++ b/lib/Lintian/Check/Team/PkgJs/Vcs.pm
@@ -0,0 +1,78 @@
+# team/pkg-js/debhelper -- lintian check script for checking Vcs-* headers -*- perl -*-
+#
+# Copyright (C) 2013 Niels Thykier <niels@thykier.net>
+# Copyright (C) 2013 gregor herrmann <gregoa@debian.org>
+# Copyright (C) 2013 Axel Beckert <abe@debian.org>
+# Copyright (C) 2019 Xavier Guimard <yadd@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Team::PkgJs::Vcs;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+my @NON_GIT_VCS_FIELDS
+  = qw(Vcs-Arch Vcs-Bzr Vcs-Cvs Vcs-Darcs Vcs-Hg Vcs-Mtn Vcs-Svn);
+my @VCS_FIELDS = (@NON_GIT_VCS_FIELDS, qw(Vcs-Git Vcs-Browser));
+
+sub source {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    # only for pkg-perl packages
+    my $maintainer = $fields->value('Maintainer');
+    return
+      unless $maintainer
+      =~ /pkg-javascript-maintainers\@lists\.alioth\.debian\.org/;
+
+    my @non_git = grep { $fields->declares($_) } @NON_GIT_VCS_FIELDS;
+    $self->hint('no-git', $_) for @non_git;
+
+    # check for team locations
+    for my $name (@VCS_FIELDS) {
+
+        next
+          unless $fields->declares($name);
+
+        my $value = $fields->value($name);
+
+        # get actual capitalization
+        my $original_name = $fields->literal_name($name);
+
+        $self->hint('no-team-url', $original_name, $value)
+          unless $value=~ m{^https://salsa.debian.org/js-team}i;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Team/PkgPerl/Testsuite.pm b/lib/Lintian/Check/Team/PkgPerl/Testsuite.pm
new file mode 100644
index 0000000..2bf6776
--- /dev/null
+++ b/lib/Lintian/Check/Team/PkgPerl/Testsuite.pm
@@ -0,0 +1,78 @@
+# team/pkg-perl/no-testsuite -- lintian check script for detecting a missing Testsuite header -*- perl -*-
+#
+# Copyright (C) 2013 Niels Thykier <niels@thykier.net>
+# Copyright (C) 2013 gregor herrmann <gregoa@debian.org>
+# Copyright (C) 2014 Niko Tyni <ntyni@debian.org>
+# Copyright (C) 2018 Florian Schlichting <fsfs@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Team::PkgPerl::Testsuite;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(none);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    # only for pkg-perl packages
+    my $maintainer = $self->processable->fields->value('Maintainer');
+    return
+      unless $maintainer=~ /pkg-perl-maintainers\@lists\.alioth\.debian\.org/;
+
+    unless ($self->processable->fields->declares('Testsuite')) {
+
+        $self->hint('no-testsuite-header');
+        return;
+    }
+
+    my @testsuites
+      = $self->processable->fields->trimmed_list('Testsuite', qr/,/);
+
+    if (none { $_ eq 'autopkgtest-pkg-perl' } @testsuites) {
+
+        $self->hint('no-team-tests');
+        return;
+    }
+
+    my $metajson = $self->processable->patched->lookup('META.json');
+    my $metayml = $self->processable->patched->lookup('META.yml');
+
+    $self->hint('autopkgtest-needs-use-name')
+      unless (defined $metajson && $metajson->size)
+      || (defined $metayml && $metayml->size)
+      || $self->processable->patched->lookup('debian/tests/pkg-perl/use-name');
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Team/PkgPerl/Vcs.pm b/lib/Lintian/Check/Team/PkgPerl/Vcs.pm
new file mode 100644
index 0000000..2818b78
--- /dev/null
+++ b/lib/Lintian/Check/Team/PkgPerl/Vcs.pm
@@ -0,0 +1,77 @@
+# team/pkg-perl/debhelper -- lintian check script for checking Vcs-* headers -*- perl -*-
+#
+# Copyright (C) 2013 Niels Thykier <niels@thykier.net>
+# Copyright (C) 2013 gregor herrmann <gregoa@debian.org>
+# Copyright (C) 2013 Axel Beckert <abe@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Team::PkgPerl::Vcs;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+my @NON_GIT_VCS_FIELDS
+  = qw(Vcs-Arch Vcs-Bzr Vcs-Cvs Vcs-Darcs Vcs-Hg Vcs-Mtn Vcs-Svn);
+my @VCS_FIELDS = (@NON_GIT_VCS_FIELDS, qw(Vcs-Git Vcs-Browser));
+
+sub source {
+    my ($self) = @_;
+
+    my $fields = $self->processable->fields;
+
+    # only for pkg-perl packages
+    my $maintainer = $fields->value('Maintainer');
+    return
+      unless $maintainer=~ /pkg-perl-maintainers\@lists\.alioth\.debian\.org/;
+
+    my @non_git = grep { $fields->declares($_) } @NON_GIT_VCS_FIELDS;
+    $self->hint('no-git', $_) for @non_git;
+
+    # check for team locations
+    for my $name (@VCS_FIELDS) {
+
+        next
+          unless $fields->declares($name);
+
+        my $value = $fields->value($name);
+
+        # get actual capitalization
+        my $original_name = $fields->literal_name($name);
+
+        $self->hint('no-team-url', $original_name, $value)
+          unless $value
+          =~ m{^https://salsa\.debian\.org/perl-team/modules/packages}i;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Team/PkgPerl/XsAbi.pm b/lib/Lintian/Check/Team/PkgPerl/XsAbi.pm
new file mode 100644
index 0000000..bb6ea56
--- /dev/null
+++ b/lib/Lintian/Check/Team/PkgPerl/XsAbi.pm
@@ -0,0 +1,95 @@
+# team/pkg-perl/xs-abi -- lintian check script for XS target directory -*- perl -*-
+#
+# Copyright (C) 2014 Damyan Ivanov <dmn@debian.org>
+# Copyright (C) 2014 Axel Beckert <abe@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Team::PkgPerl::XsAbi;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Dpkg::Version;
+
+use Lintian::Relation;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+has relies_on_modern_api => (
+    is => 'rw',
+    lazy => 1,
+    coerce => sub { my ($boolean) = @_; return ($boolean // 0); },
+    default => sub {
+        my ($self) = @_;
+
+        return 0
+          if $self->processable->fields->value('Architecture') eq 'all';
+
+        my $depends = $self->processable->relation('strong');
+
+        my $api_version = $depends->visit(
+            sub {
+                my ($prerequisite) = @_;
+
+                if ($prerequisite =~ /^perlapi-(\d[\d.]*)$/) {
+                    return $1;
+                }
+
+                return;
+            },
+            Lintian::Relation::VISIT_OR_CLAUSE_FULL
+              | Lintian::Relation::VISIT_STOP_FIRST_MATCH
+        );
+
+        return 0
+          unless defined $api_version;
+
+        return 1
+          if version_compare_relation($api_version, REL_GE, '5.19.11');
+
+        return 0;
+    }
+);
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->is_file;
+
+    return
+      unless $item->name =~ m{^usr/lib/perl5/};
+
+    $self->pointed_hint('legacy-vendorarch-directory', $item->pointer)
+      if $self->relies_on_modern_api;
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Template/DhMake/Control/Vcs.pm b/lib/Lintian/Check/Template/DhMake/Control/Vcs.pm
new file mode 100644
index 0000000..11bf366
--- /dev/null
+++ b/lib/Lintian/Check/Template/DhMake/Control/Vcs.pm
@@ -0,0 +1,77 @@
+# template/dh-make/control/vcs -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Template::DhMake::Control::Vcs;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $item = $self->processable->debian_control->item;
+    return
+      unless defined $item;
+
+    my @lines = split(/\n/, $item->decoded_utf8);
+
+    my $line;
+    my $position = 1;
+    while (defined($line = shift @lines)) {
+
+        $line =~ s{\s*$}{};
+
+        if (
+            $line =~ m{\A \# \s* Vcs-(?:Git|Browser): \s*
+                       (?:git|http)://git\.debian\.org/
+                       (?:\?p=)?collab-maint/<pkg>\.git}smx
+        ) {
+
+            my $pointer = $item->pointer($position);
+
+            $self->pointed_hint('control-file-contains-dh-make-vcs-comment',
+                $pointer, $line);
+
+            # once per source
+            last;
+        }
+
+    } continue {
+        ++$position;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Testsuite.pm b/lib/Lintian/Check/Testsuite.pm
new file mode 100644
index 0000000..46556e5
--- /dev/null
+++ b/lib/Lintian/Check/Testsuite.pm
@@ -0,0 +1,352 @@
+# testsuite -- lintian check script -*- perl -*-
+
+# Copyright (C) 2013 Nicolas Boulenguez <nicolas@debian.org>
+# Copyright (C) 2017-2020 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+
+# This file is part of lintian.
+
+# Lintian is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# Lintian is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with Lintian.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Check::Testsuite;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::Compare;
+use List::SomeUtils qw(any none uniq);
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Deb822;
+use Lintian::Deb822::Constants qw(DCTRL_COMMENTS_AT_EOL);
+use Lintian::Relation;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $DOT => q{.};
+const my $DOUBLE_QUOTE => q{"};
+
+const my @KNOWN_FIELDS => qw(
+  Tests
+  Restrictions
+  Features
+  Depends
+  Tests-Directory
+  Test-Command
+  Architecture
+  Classes
+);
+
+my %KNOWN_FEATURES = map { $_ => 1 } qw();
+
+our $PYTHON3_ALL_DEPEND
+  = 'python3-all:any | python3-all-dev:any | python3-all-dbg:any';
+
+my %KNOWN_SPECIAL_DEPENDS = map { $_ => 1 } qw(
+  @
+  @builddeps@
+  @recommends@
+);
+
+sub source {
+    my ($self) = @_;
+
+    my $KNOWN_TESTSUITES= $self->data->load('testsuite/known-testsuites');
+
+    my $debian_control = $self->processable->debian_control;
+
+    my $testsuite = $debian_control->source_fields->value('Testsuite');
+    my @testsuites = split(/\s*,\s*/, $testsuite);
+
+    my $lc = List::Compare->new(\@testsuites, [$KNOWN_TESTSUITES->all]);
+    my @unknown = $lc->get_Lonly;
+
+    my $control_position
+      = $debian_control->source_fields->position('Testsuite');
+    my $control_pointer = $debian_control->item->pointer($control_position);
+
+    $self->pointed_hint('unknown-testsuite', $control_pointer, $_)for @unknown;
+
+    my $tests_control
+      = $self->processable->patched->resolve_path('debian/tests/control');
+
+    # field added automatically since dpkg 1.17 when d/tests/control is present
+    $self->pointed_hint('unnecessary-testsuite-autopkgtest-field',
+        $control_pointer)
+      if (any { $_ eq 'autopkgtest' } @testsuites) && defined $tests_control;
+
+    # need d/tests/control for plain autopkgtest
+    $self->pointed_hint('missing-tests-control', $control_pointer)
+      if (any { $_ eq 'autopkgtest' } @testsuites) && !defined $tests_control;
+
+    die encode_utf8('debian tests control is not a regular file')
+      if defined $tests_control && !$tests_control->is_regular_file;
+
+    if (defined $tests_control && $tests_control->is_valid_utf8) {
+
+        # another check complains about invalid encoding
+        my $contents = $tests_control->decoded_utf8;
+
+        my $control_file = Lintian::Deb822->new;
+        $control_file->parse_string($contents, DCTRL_COMMENTS_AT_EOL);
+
+        my @sections = @{$control_file->sections};
+
+        $self->pointed_hint('empty-debian-tests-control',
+            $tests_control->pointer)
+          unless @sections;
+
+        $self->check_control_paragraph($tests_control, $_) for @sections;
+
+        my @thorough
+          = grep { $_->value('Restrictions') !~ m{\bsuperficial\b} } @sections;
+        $self->pointed_hint('superficial-tests', $tests_control->pointer)
+          if @sections && !@thorough;
+
+        if (scalar @sections == 1) {
+
+            my $section = $sections[0];
+
+            my $command = $section->unfolded_value('Test-Command');
+            my $position = $section->position('Test-Command');
+            my $pointer = $tests_control->pointer($position);
+
+            $self->pointed_hint('no-op-testsuite', $pointer)
+              if $command =~ m{^ \s* (?:/bin/)? true \s* $}sx;
+        }
+    }
+
+    my $control_autodep8
+      = $self->processable->patched->resolve_path(
+        'debian/tests/control.autodep8');
+    $self->pointed_hint('debian-tests-control-autodep8-is-obsolete',
+        $control_autodep8->pointer)
+      if defined $control_autodep8;
+
+    return;
+}
+
+sub check_control_paragraph {
+    my ($self, $tests_control, $section) = @_;
+
+    my $section_pointer = $tests_control->pointer($section->position);
+
+    $self->pointed_hint('no-tests', $section_pointer)
+      unless $section->declares('Tests') || $section->declares('Test-Command');
+
+    $self->pointed_hint('conflicting-test-fields', $section_pointer, 'Tests',
+        'Test-Command')
+      if $section->declares('Tests') && $section->declares('Test-Command');
+
+    my @lowercase_names = map { lc } $section->names;
+    my @lowercase_known = map { lc } @KNOWN_FIELDS;
+
+    my $lc = List::Compare->new(\@lowercase_names, \@lowercase_known);
+    my @lowercase_unknown = $lc->get_Lonly;
+
+    my @unknown = map { $section->literal_name($_) } @lowercase_unknown;
+    $self->pointed_hint('unknown-runtime-tests-field',
+        $tests_control->pointer($section->position($_)), $_)
+      for @unknown;
+
+    my @features = $section->trimmed_list('Features', qr/ \s* , \s* | \s+ /x);
+    for my $feature (@features) {
+
+        my $position = $section->position('Features');
+        my $pointer = $tests_control->pointer($position);
+
+        $self->pointed_hint('unknown-runtime-tests-feature',$pointer, $feature)
+          unless exists $KNOWN_FEATURES{$feature}
+          || $feature =~ m/^test-name=\S+/;
+    }
+
+    my $KNOWN_RESTRICTIONS= $self->data->load('testsuite/known-restrictions');
+    my $KNOWN_OBSOLETE_RESTRICTIONS
+      = $self->data->load('testsuite/known-obsolete-restrictions');
+
+    my @restrictions
+      = $section->trimmed_list('Restrictions', qr/ \s* , \s* | \s+ /x);
+    for my $restriction (@restrictions) {
+
+        my $position = $section->position('Restrictions');
+        my $pointer = $tests_control->pointer($position);
+
+        $self->pointed_hint('unknown-runtime-tests-restriction',
+            $pointer, $restriction)
+          unless $KNOWN_RESTRICTIONS->recognizes($restriction);
+
+        $self->pointed_hint('obsolete-runtime-tests-restriction',
+            $pointer, $restriction)
+          if $KNOWN_OBSOLETE_RESTRICTIONS->recognizes($restriction);
+    }
+
+    my $test_command = $section->unfolded_value('Test-Command');
+
+    # trim both sides
+    $test_command =~ s/^\s+|\s+$//g;
+
+    $self->pointed_hint('backgrounded-test-command',
+        $tests_control->pointer($section->position('Test-Command')),
+        $test_command)
+      if $test_command =~ / & $/x;
+
+    my $directory = $section->unfolded_value('Tests-Directory')
+      || 'debian/tests';
+
+    my $tests_position = $section->position('Tests');
+    my $tests_pointer = $tests_control->pointer($tests_position);
+
+    my @tests = uniq +$section->trimmed_list('Tests', qr/ \s* , \s* | \s+ /x);
+
+    my @illegal_names = grep { !m{^ [ [:alnum:] \+ \- \. / ]+ $}x } @tests;
+    $self->pointed_hint('illegal-runtime-test-name', $tests_pointer, $_)
+      for @illegal_names;
+
+    my @paths;
+    if ($directory eq $DOT) {
+
+        # Special case with "Tests-Directory: ." (see #849880)
+        @paths = @tests;
+
+    } else {
+        @paths = map { "$directory/$_" } @tests;
+    }
+
+    my $debian_control = $self->processable->debian_control;
+
+    my $depends_norestriction = Lintian::Relation->new;
+    $depends_norestriction->load($section->unfolded_value('Depends'));
+
+    my $all_tests_use_supported = 1;
+
+    for my $path (@paths) {
+
+        my $item = $self->processable->patched->resolve_path($path);
+        if (!defined $item) {
+
+            $self->pointed_hint('missing-runtime-test-file', $tests_pointer,
+                $path);
+            next;
+        }
+
+        if (!$item->is_open_ok) {
+
+            $self->pointed_hint('runtime-test-file-is-not-a-regular-file',
+                $tests_pointer, $path);
+            next;
+        }
+
+        my $queries_all_python_versions = 0;
+
+        open(my $fd, '<', $item->unpacked_path)
+          or die encode_utf8('Cannot open ' . $item->unpacked_path);
+
+        my $position = 1;
+        while (my $line = <$fd>) {
+
+            my $pointer = $item->pointer($position);
+
+            $self->pointed_hint('uses-deprecated-adttmp', $pointer)
+              if $line =~ /ADTTMP/;
+
+            if ($line =~ /(py3versions)((?:\s+--?\w+)*)/) {
+
+                my $command = $1 . $2;
+                my $options = $2;
+
+                $self->pointed_hint(
+                    'runtime-test-file-uses-installed-python-versions',
+                    $pointer, $command)
+                  if $options =~ /\s(?:-\w*i|--installed)/;
+
+                $self->pointed_hint(
+'runtime-test-file-uses-supported-python-versions-without-test-depends',
+                    $pointer,
+                    $command
+                  )
+                  if $options =~ /\s(?:-\w*s|--supported)/
+                  && !$depends_norestriction->satisfies($PYTHON3_ALL_DEPEND);
+
+                $self->pointed_hint('declare-python-versions-for-test',
+                    $pointer, $command)
+                  if $options =~ m{ \s (?: -\w*r | --requested ) }x
+                  && !$debian_control->source_fields->declares(
+                    'X-Python3-Version');
+
+                $queries_all_python_versions = 1
+                  if $options =~ m{ \s (?: -\w*s | --supported ) }x;
+            }
+
+        } continue {
+            ++$position;
+        }
+
+        close $fd;
+
+        $all_tests_use_supported = 0
+          if !$queries_all_python_versions;
+
+        $self->pointed_hint('test-leaves-python-version-untested',
+            $item->pointer)
+          if $depends_norestriction->satisfies($PYTHON3_ALL_DEPEND)
+          && !$queries_all_python_versions;
+    }
+
+    if (   $debian_control->source_fields->declares('X-Python3-Version')
+        && $all_tests_use_supported) {
+
+        my $position
+          = $debian_control->source_fields->position('X-Python3-Version');
+        my $pointer = $debian_control->item->pointer($position);
+
+        $self->pointed_hint('drop-python-version-declaration',$pointer);
+    }
+
+    if ($section->declares('Depends')) {
+
+        my $depends = $section->unfolded_value('Depends');
+
+        # trim both sides
+        $depends =~ s/^\s+|\s+$//g;
+
+        my $relation = Lintian::Relation->new->load($depends);
+
+        # autopkgtest allows @ as predicate as an exception
+        my @unparsable = grep { !exists $KNOWN_SPECIAL_DEPENDS{$_} }
+          $relation->unparsable_predicates;
+
+        my $position = $section->position('Depends');
+        my $pointer = $tests_control->pointer($position);
+
+        $self->pointed_hint('testsuite-dependency-has-unparsable-elements',
+            $pointer, $DOUBLE_QUOTE . $_ . $DOUBLE_QUOTE)
+          for @unparsable;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Triggers.pm b/lib/Lintian/Check/Triggers.pm
new file mode 100644
index 0000000..738f3c6
--- /dev/null
+++ b/lib/Lintian/Check/Triggers.pm
@@ -0,0 +1,145 @@
+# triggers -- lintian check script -*- perl -*-
+
+# Copyright (C) 2017 Niels Thykier
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Triggers;
+
+use v5.20;
+use warnings;
+use utf8;
+use autodie qw(open);
+
+use Const::Fast;
+use List::SomeUtils qw(all);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+const my $SPACE => q{ };
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+has TRIGGER_TYPES => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %trigger_types;
+
+        my $data
+          = $self->data->load('triggers/trigger-types',qr{ \s* => \s* }x);
+        for my $type ($data->all) {
+
+            my $attributes  = $data->value($type);
+
+            my %one_type;
+
+            for my $pair (split(m{ \s* , \s* }x, $attributes)) {
+
+                my ($flag, $setting) = split(m{ \s* = \s* }x, $pair, 2);
+                $one_type{$flag} = $setting;
+            }
+
+            die encode_utf8(
+"Invalid trigger-types: $type is defined as implicit-await but not await"
+              )
+              if $one_type{'implicit-await'}
+              && !$one_type{await};
+
+            $trigger_types{$type} = \%one_type;
+        }
+
+        return \%trigger_types;
+    }
+);
+
+sub visit_control_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->name eq 'triggers';
+
+    my @lines = split(m{\n}, $item->decoded_utf8);
+
+    my %positions_by_trigger_name;
+
+    my $position = 1;
+    while (defined(my $line = shift @lines)) {
+
+        # trim both ends
+        $line =~ s/^\s+|\s+$//g;
+
+        next
+          if $line =~ m/^(?:\s*)(?:#.*)?$/;
+
+        my ($trigger_type, $trigger_name) = split($SPACE, $line, 2);
+        next
+          unless all { length } ($trigger_type, $trigger_name);
+
+        $positions_by_trigger_name{$trigger_name} //= [];
+        push(@{$positions_by_trigger_name{$trigger_name}}, $position);
+
+        my $trigger_info = $self->TRIGGER_TYPES->{$trigger_type};
+        if (!$trigger_info) {
+
+            $self->pointed_hint('unknown-trigger', $item->pointer($position),
+                $trigger_type);
+            next;
+        }
+
+        $self->pointed_hint('uses-implicit-await-trigger',
+            $item->pointer($position),
+            $trigger_type)
+          if $trigger_info->{'implicit-await'};
+
+    } continue {
+        ++$position;
+    }
+
+    my @duplicates= grep { @{$positions_by_trigger_name{$_}} > 1 }
+      keys %positions_by_trigger_name;
+
+    for my $trigger_name (@duplicates) {
+
+        my $indicator
+          = $LEFT_PARENTHESIS . 'lines'
+          . $SPACE
+          . join($SPACE,
+            sort { $a <=> $b }@{$positions_by_trigger_name{$trigger_name}})
+          . $RIGHT_PARENTHESIS;
+
+        $self->pointed_hint('repeated-trigger-name', $item->pointer,
+            $trigger_name, $indicator);
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Udev.pm b/lib/Lintian/Check/Udev.pm
new file mode 100644
index 0000000..4d1779a
--- /dev/null
+++ b/lib/Lintian/Check/Udev.pm
@@ -0,0 +1,172 @@
+# udev -- lintian check script -*- perl -*-
+
+# Copyright (C) 2016 Petter Reinholdtsen
+# Copyright (C) 2018 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Udev;
+
+use v5.20;
+use warnings;
+use utf8;
+use autodie qw(open);
+
+use Const::Fast;
+
+const my $EMPTY => q{};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+# Check /lib/udev/rules.d/, detect use of MODE="0666" and use of
+# GROUP="plugdev" without TAG+="uaccess".
+
+sub installable {
+    my ($self) = @_;
+
+    foreach my $lib_dir (qw(usr/lib lib)) {
+        my $rules_dir
+          = $self->processable->installed->resolve_path(
+            "$lib_dir/udev/rules.d/");
+        next
+          unless $rules_dir;
+
+        for my $item ($rules_dir->children) {
+
+            if (!$item->is_open_ok) {
+
+                $self->pointed_hint('udev-rule-unreadable', $item->pointer);
+                next;
+            }
+
+            $self->check_udev_rules($item);
+        }
+    }
+
+    return;
+}
+
+sub check_rule {
+    my ($self, $item, $position, $in_goto, $rule) = @_;
+
+    # for USB, if everyone or the plugdev group members are
+    # allowed access, the uaccess tag should be used too.
+    $self->pointed_hint(
+        'udev-rule-missing-uaccess',
+        $item->pointer($position),
+        'user accessible device missing TAG+="uaccess"'
+      )
+      if $rule =~ m/SUBSYSTEM=="usb"/
+      && ( $rule =~ m/GROUP="plugdev"/
+        || $rule =~ m/MODE="0666"/)
+      && $rule !~ m/ENV\{COLOR_MEASUREMENT_DEVICE\}/
+      && $rule !~ m/ENV\{DDC_DEVICE\}/
+      && $rule !~ m/ENV\{ID_CDROM\}/
+      && $rule !~ m/ENV\{ID_FFADO\}/
+      && $rule !~ m/ENV\{ID_GPHOTO2\}/
+      && $rule !~ m/ENV\{ID_HPLIP\}/
+      && $rule !~ m/ENV\{ID_INPUT_JOYSTICK\}/
+      && $rule !~ m/ENV\{ID_MAKER_TOOL\}/
+      && $rule !~ m/ENV\{ID_MEDIA_PLAYER\}/
+      && $rule !~ m/ENV\{ID_PDA\}/
+      && $rule !~ m/ENV\{ID_REMOTE_CONTROL\}/
+      && $rule !~ m/ENV\{ID_SECURITY_TOKEN\}/
+      && $rule !~ m/ENV\{ID_SMARTCARD_READER\}/
+      && $rule !~ m/ENV\{ID_SOFTWARE_RADIO\}/
+      && $rule !~ m/TAG\+="uaccess"/;
+
+    # Matching rules mentioning vendor/product should also specify
+    # subsystem, as vendor/product is subsystem specific.
+    $self->pointed_hint(
+        'udev-rule-missing-subsystem',
+        $item->pointer($position),
+        'vendor/product matching missing SUBSYSTEM specifier'
+      )
+      if $rule =~ m/ATTR\{idVendor\}=="[0-9a-fA-F]+"/
+      && $rule =~ m/ATTR\{idProduct\}=="[0-9a-fA-F]*"/
+      && !$in_goto
+      && $rule !~ m/SUBSYSTEM=="[^"]+"/;
+
+    return 0;
+}
+
+sub check_udev_rules {
+    my ($self, $item) = @_;
+
+    my $contents = $item->decoded_utf8;
+    my @lines = split(/\n/, $contents);
+
+    my $continued = $EMPTY;
+    my $in_goto = $EMPTY;
+    my $result = 0;
+
+    my $position = 1;
+    while (defined(my $line = shift @lines)) {
+
+        if (length $continued) {
+            $line = $continued . $line;
+            $continued = $EMPTY;
+        }
+
+        if ($line =~ /^(.*)\\$/) {
+            $continued = $1;
+            next;
+        }
+
+        # Skip comments
+        next
+          if $line =~ /^#.*/;
+
+        $in_goto = $EMPTY
+          if $line =~ /LABEL="[^"]+"/;
+
+        $in_goto = $line
+          if $line =~ /SUBSYSTEM!="[^"]+"/
+          && $line =~ /GOTO="[^"]+"/;
+
+        $result |= $self->check_rule($item, $position, $in_goto, $line);
+
+    } continue {
+        $position++;
+    }
+
+    return $result;
+}
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->name =~ m{^etc/udev/};
+
+    # /etc/udev/rules.d
+    $self->pointed_hint('udev-rule-in-etc', $item->pointer)
+      if $item->name =~ m{^etc/udev/rules\.d/\S};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Unpack.pm b/lib/Lintian/Check/Unpack.pm
new file mode 100644
index 0000000..9395942
--- /dev/null
+++ b/lib/Lintian/Check/Unpack.pm
@@ -0,0 +1,67 @@
+# unpack -- lintian check script -*- perl -*-
+
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Unpack;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $processable = $self->processable;
+
+    $self->hint('unpack-message-for-source', $_)
+      for @{$processable->patched->unpack_messages};
+
+    # empty for native
+    $self->hint('unpack-message-for-orig', $_)
+      for @{$processable->orig->unpack_messages};
+
+    return;
+}
+
+sub installable {
+    my ($self) = @_;
+
+    my $processable = $self->processable;
+
+    $self->hint('unpack-message-for-deb-data', $_)
+      for @{$processable->installed->unpack_messages};
+
+    $self->hint('unpack-message-for-deb-control', $_)
+      for @{$processable->control->unpack_messages};
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/UpstreamSignature.pm b/lib/Lintian/Check/UpstreamSignature.pm
new file mode 100644
index 0000000..3278e87
--- /dev/null
+++ b/lib/Lintian/Check/UpstreamSignature.pm
@@ -0,0 +1,126 @@
+# upstream-signature -- lintian check script -*- perl -*-
+#
+# Copyright (C) 2019 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::UpstreamSignature;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Path::Tiny;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub source {
+    my ($self) = @_;
+
+    my $SIGNING_KEY_FILENAMES
+      = $self->data->load('common/signing-key-filenames');
+
+    my @keynames = $SIGNING_KEY_FILENAMES->all;
+    my @keypaths
+      = map { $self->processable->patched->resolve_path("debian/$_") }
+      @keynames;
+    my @keys = grep { $_ && $_->is_file } @keypaths;
+
+    # in uscan's gittag mode,signature will never match
+    my $watch = $self->processable->patched->resolve_path('debian/watch');
+    my $gittag = $watch && $watch->bytes =~ /pgpmode=gittag/;
+
+    my @filenames = sort keys %{$self->processable->files};
+    my @origtar= grep { /^.*\.orig(?:-[A-Za-z\d-]+)?\.tar\./ }
+      grep { !/\.asc$/ }@filenames;
+
+    my %signatures;
+    for my $filename (@origtar) {
+
+        my ($uncompressed) = ($filename =~ /(^.*\.tar)/);
+
+        my @componentsigs;
+        for my $tarball ($filename, $uncompressed) {
+            my $signaturename = "$tarball.asc";
+            push(@componentsigs, $signaturename)
+              if exists $self->processable->files->{$signaturename};
+        }
+
+        $signatures{$filename} = \@componentsigs;
+    }
+
+    # orig tarballs should be signed if upstream's public key is present
+    if (@keys && !$self->processable->repacked && !$gittag) {
+
+        for my $filename (@origtar) {
+
+            $self->hint('orig-tarball-missing-upstream-signature', $filename)
+              unless scalar @{$signatures{$filename}};
+        }
+    }
+
+    my $parentdir = path($self->processable->path)->parent->stringify;
+
+    # check signatures
+    my @allsigs = map { @{$signatures{$_}} } @origtar;
+    for my $signature (@allsigs) {
+        my $sig_file = path($parentdir)->child($signature);
+        # Only try to slurp file if it exists. Otherwise Path::Tiny ≥
+        # 0.142 will bail out. (Returned empty string instead before
+        # that version.)
+        next unless $sig_file->is_file;
+
+        # take from location near input file
+        my $contents = $sig_file->slurp;
+
+        if ($contents =~ /^-----BEGIN PGP ARMORED FILE-----/m) {
+
+            if ($contents =~ /^LS0tLS1CRUd/m) {
+                # doubly armored
+                $self->hint('doubly-armored-upstream-signature', $signature);
+
+            } else {
+                # non standard armored header
+                $self->hint('explicitly-armored-upstream-signature',
+                    $signature);
+            }
+
+            my @spurious = ($contents =~ /\n([^:\n]+):/g);
+            $self->hint('spurious-fields-in-upstream-signature',
+                $signature, @spurious)
+              if @spurious;
+        }
+
+        # multiple signatures in one file
+        $self->hint('concatenated-upstream-signatures', $signature)
+          if $contents
+          =~ m/(?:-----BEGIN PGP SIGNATURE-----[^-]*-----END PGP SIGNATURE-----\s*){2,}/;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Usrmerge.pm b/lib/Lintian/Check/Usrmerge.pm
new file mode 100644
index 0000000..a435470
--- /dev/null
+++ b/lib/Lintian/Check/Usrmerge.pm
@@ -0,0 +1,66 @@
+# usrmerge -- lintian check script -*- perl -*-
+
+# Copyright (C) 2016 Marco d'Itri
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Usrmerge;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    return
+      unless $item->name =~ m{^(?:s?bin|lib(?:|[ox]?32|64))/};
+
+    my $usrfile = $self->processable->installed->lookup("usr/$item");
+
+    return
+      unless defined $usrfile;
+
+    return
+      if $item->is_dir and $usrfile->is_dir;
+
+    if ($item =~ m{^lib.+\.(?:so[\.0-9]*|a)$}) {
+        $self->pointed_hint('library-in-root-and-usr', $item->pointer,
+            'already in:', $usrfile->name);
+
+    } else {
+        $self->pointed_hint(
+            'file-in-root-and-usr', $item->pointer,
+            'already in:', $usrfile->name
+        );
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Vim.pm b/lib/Lintian/Check/Vim.pm
new file mode 100644
index 0000000..ef889f5
--- /dev/null
+++ b/lib/Lintian/Check/Vim.pm
@@ -0,0 +1,53 @@
+# vim -- lintian check script -*- perl -*-
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Vim;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub visit_installed_files {
+    my ($self, $item) = @_;
+
+    if ($item->name =~ m{^usr/share/vim/vim(?:current|\d\d)/([^/]+)}){
+        my $is_vimhelp
+          = $1 eq 'doc' && $self->processable->name =~ /^vimhelp-\w+$/;
+        my $is_vim = $self->processable->source_name =~ /vim/;
+
+        $self->pointed_hint('vim-addon-within-vim-runtime-path',$item->pointer)
+          unless $is_vim || $is_vimhelp;
+    }
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Check/Vim/Addons.pm b/lib/Lintian/Check/Vim/Addons.pm
new file mode 100644
index 0000000..9823f0c
--- /dev/null
+++ b/lib/Lintian/Check/Vim/Addons.pm
@@ -0,0 +1,48 @@
+# vim -- lintian check script -*- perl -*-
+
+# Copyright (C) Louis-Philippe Veronneau
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Check::Vim::Addons;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Check';
+
+sub installable {
+    my ($self) = @_;
+
+    $self->hint('obsolete-vim-addon-manager')
+      if $self->processable->relation('strong')
+      ->satisfies('vim-addon-manager');
+
+    return;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Conffiles.pm b/lib/Lintian/Conffiles.pm
new file mode 100644
index 0000000..1daa2c4
--- /dev/null
+++ b/lib/Lintian/Conffiles.pm
@@ -0,0 +1,162 @@
+# -*- perl -*- Lintian::Processable::Installable::Conffiles
+#
+# Copyright (C) 2019 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Conffiles;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Lintian::Conffiles::Entry;
+
+const my $SPACE => q{ };
+const my $NEWLINE => qq{\n};
+
+const my $TRUE => 1;
+const my $FALSE => 0;
+
+use Moo;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Conffiles - access to collected control data for conffiles
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Conffiles provides an interface to control data for conffiles.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item by_file
+
+=cut
+
+has by_file => (is => 'rw', default => sub { {} });
+
+=item parse
+
+=cut
+
+sub parse {
+    my ($self, $item) = @_;
+
+    return
+      unless $item && $item->is_valid_utf8;
+
+    my @lines = split($NEWLINE, $item->decoded_utf8);
+
+    # dpkg strips whitespace (using isspace) from the right hand
+    # side of the file name.
+
+    # trim right
+    s/\s+$// for @lines;
+
+    my $position = 1;
+    for my $line (@lines) {
+
+        next
+          unless length $line;
+
+        my @words = split($SPACE, $line);
+        my $relative = pop @words;
+
+        my $conffile = Lintian::Conffiles::Entry->new;
+
+        # path must be absolute
+        if ($relative =~ s{^ / }{}x) {
+            $conffile->is_relative($FALSE);
+        } else {
+            $conffile->is_relative($TRUE);
+        }
+
+        $conffile->instructions(\@words);
+        $conffile->position($position);
+
+        # but use relative path as key
+        $self->by_file->{$relative} //= [];
+        push(@{$self->by_file->{$relative}}, $conffile);
+
+    } continue {
+        ++$position;
+    }
+
+    return;
+}
+
+=item all
+
+Returns a list of absolute filenames found for conffiles.
+
+=cut
+
+sub all {
+    my ($self) = @_;
+
+    return keys %{$self->by_file};
+}
+
+=item is_known (FILE)
+
+Returns a truth value if FILE is listed in the conffiles control file.
+If the control file is not present or FILE is not listed in it, it
+returns C<undef>.
+
+Note that FILE should be the filename relative to the package root
+(even though the control file uses absolute paths).  If the control
+file does relative paths, they are assumed to be relative to the
+package root as well (and used without warning).
+
+=cut
+
+sub is_known {
+    my ($self, $relative) = @_;
+
+    return 1
+      if exists $self->by_file->{$relative};
+
+    return 0;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Conffiles/Entry.pm b/lib/Lintian/Conffiles/Entry.pm
new file mode 100644
index 0000000..488cd99
--- /dev/null
+++ b/lib/Lintian/Conffiles/Entry.pm
@@ -0,0 +1,72 @@
+# -*- perl -*- Lintian::Conffiles::Entry
+#
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Conffiles::Entry;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Conffiles::Entry - access to collected control data for conffiles
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Conffiles::Entry provides an interface to control data for conffiles.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item instructions
+=item is_relative
+=item position
+
+=cut
+
+has instructions => (is => 'rw', default => sub { [] });
+has is_relative => (is => 'rw');
+has position => (is => 'rw');
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data.pm b/lib/Lintian/Data.pm
new file mode 100644
index 0000000..6a0b227
--- /dev/null
+++ b/lib/Lintian/Data.pm
@@ -0,0 +1,354 @@
+# Copyright (C) 2011 Niels Thykier <niels@thykier.net>
+# Copyright (C) 2018 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+# Copyright (C) 2022 Axel Beckert
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Data;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Data::Architectures;
+use Lintian::Data::Archive::AutoRejection;
+use Lintian::Data::Archive::Sections;
+use Lintian::Data::Buildflags::Hardening;
+use Lintian::Data::Debhelper::Addons;
+use Lintian::Data::Debhelper::Commands;
+use Lintian::Data::Debhelper::Levels;
+use Lintian::Data::Fonts;
+use Lintian::Data::InitD::VirtualFacilities;
+use Lintian::Data::Policy::Releases;
+use Lintian::Data::Provides::MailTransportAgent;
+use Lintian::Data::Stylesheet;
+use Lintian::Data::Traditional;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::Authorities';
+
+=head1 NAME
+
+Lintian::Data - Data parser for Lintian
+
+=head1 SYNOPSIS
+
+ my $profile = Lintian::Data->new (vendor => 'debian');
+
+=head1 DESCRIPTION
+
+Lintian::Data handles finding, parsing and implementation of Lintian Data
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item vendor
+
+=item data_paths
+
+=item data_cache
+
+=cut
+
+has vendor => (is => 'rw');
+
+has data_paths => (
+    is => 'rw',
+    coerce => sub { my ($arrayref) = @_; return ($arrayref // []); },
+    default => sub { [] }
+);
+
+has data_cache => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+=item load
+
+=cut
+
+sub load {
+    my ($self, $location, $separator) = @_;
+
+    croak encode_utf8('no data type specified')
+      unless $location;
+
+    unless (exists $self->data_cache->{$location}) {
+
+        my $cache = Lintian::Data::Traditional->new;
+        $cache->location($location);
+        $cache->separator($separator);
+
+        $cache->load($self->data_paths, $self->vendor);
+
+        $self->data_cache->{$location} = $cache;
+    }
+
+    return $self->data_cache->{$location};
+}
+
+=item all_sources
+
+=cut
+
+sub all_sources {
+    my ($self) = @_;
+
+    my @sources = (
+        $self->architectures,$self->auto_rejection,
+        $self->debhelper_addons,$self->debhelper_commands,
+        $self->debhelper_levels,$self->fonts,
+        $self->hardening_buildflags,$self->mail_transport_agents,
+        $self->policy_releases,$self->sections,
+        #$self->style_sheet,
+        $self->virtual_initd_facilities
+    );
+
+    return @sources;
+}
+
+=item architectures
+
+=cut
+
+has architectures => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $architectures = Lintian::Data::Architectures->new;
+        $architectures->load($self->data_paths, $self->vendor);
+
+        return $architectures;
+    }
+);
+
+=item auto_rejection
+
+=cut
+
+has auto_rejection => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $auto_rejection = Lintian::Data::Archive::AutoRejection->new;
+        $auto_rejection->load($self->data_paths, $self->vendor);
+
+        return $auto_rejection;
+    }
+);
+
+=item debhelper_addons
+
+=cut
+
+has debhelper_addons => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $addons = Lintian::Data::Debhelper::Addons->new;
+        $addons->load($self->data_paths, $self->vendor);
+
+        return $addons;
+    }
+);
+
+=item debhelper_commands
+
+=cut
+
+has debhelper_commands => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $commands = Lintian::Data::Debhelper::Commands->new;
+        $commands->load($self->data_paths, $self->vendor);
+
+        return $commands;
+    }
+);
+
+=item debhelper_levels
+
+=cut
+
+has debhelper_levels => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $levels = Lintian::Data::Debhelper::Levels->new;
+        $levels->load($self->data_paths, $self->vendor);
+
+        return $levels;
+    }
+);
+
+=item fonts
+
+=cut
+
+has fonts => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $fonts = Lintian::Data::Fonts->new;
+        $fonts->load($self->data_paths, $self->vendor);
+
+        return $fonts;
+    }
+);
+
+=item hardening_buildflags
+
+=cut
+
+has hardening_buildflags => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $buildflags = Lintian::Data::Buildflags::Hardening->new;
+        $buildflags->load($self->data_paths, $self->vendor);
+
+        return $buildflags;
+    }
+);
+
+=item mail_transport_agents
+
+=cut
+
+has mail_transport_agents => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $manual = Lintian::Data::Provides::MailTransportAgent->new;
+        $manual->load($self->data_paths, $self->vendor);
+
+        return $manual;
+    }
+);
+
+=item policy_releases
+
+=cut
+
+has policy_releases => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $releases = Lintian::Data::Policy::Releases->new;
+        $releases->load($self->data_paths, $self->vendor);
+
+        return $releases;
+    }
+);
+
+=item sections
+
+=cut
+
+has sections => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $sections = Lintian::Data::Archive::Sections->new;
+        $sections->load($self->data_paths, $self->vendor);
+
+        return $sections;
+    }
+);
+
+=item style_sheet
+
+=cut
+
+has style_sheet => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $stylesheets = Lintian::Data::Stylesheet->new;
+        $stylesheets->load($self->data_paths, $self->vendor);
+
+        return $stylesheets;
+    }
+);
+
+=item virtual_initd_facilities
+
+=cut
+
+has virtual_initd_facilities => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $facilities = Lintian::Data::InitD::VirtualFacilities->new;
+        $facilities->load($self->data_paths, $self->vendor);
+
+        return $facilities;
+    }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Niels Thykier <niels@thykier.net> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Architectures.pm b/lib/Lintian/Data/Architectures.pm
new file mode 100644
index 0000000..c45ced4
--- /dev/null
+++ b/lib/Lintian/Data/Architectures.pm
@@ -0,0 +1,441 @@
+# -*- perl -*-
+
+# Copyright (C) 2011-2012 Niels Thykier <niels@thykier.net>
+#  - Based on a shell script by Raphael Geissert <atomo64@gmail.com>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Architectures;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(first_value);
+use Unicode::UTF8 qw(decode_utf8);
+
+use Lintian::IPC::Run3 qw(safe_qx);
+
+const my $EMPTY => q{};
+const my $SLASH => q{/};
+
+const my $HOST_VARIABLES => q{host_variables};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::PreambledJSON';
+
+=encoding utf-8
+
+=head1 NAME
+
+Lintian::Data::Architectures -- Lintian API for handling architectures and wildcards
+
+=head1 SYNOPSIS
+
+ use Lintian::Data::Architectures;
+
+=head1 DESCRIPTION
+
+Lintian API for checking and expanding architectures and architecture
+wildcards.  The functions are backed by a L<data|Lintian::Data> file,
+so it may be out of date (use private/refresh-archs to update it).
+
+Generally all architecture names are in the format "$os-$architecture" and
+wildcards are "$os-any" or "any-$cpu", though there are exceptions:
+
+Note that the architecture and cpu name are not always identical
+(example architecture "armhf" has cpu name "arm").
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item title
+
+=item location
+
+=item host_variables
+
+=item C<wildcards>
+
+=item C<names>
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'DEB_HOST_* Variables from Dpkg'
+);
+
+has location => (
+    is => 'rw',
+    default => 'architectures/host.json'
+);
+
+has host_variables => (
+    is => 'rw',
+    default => sub { {} },
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); }
+);
+
+has deb_host_multiarch => (
+    is => 'rw',
+    lazy => 1,
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub {
+        my ($self) = @_;
+
+        my %deb_host_multiarch;
+
+        $deb_host_multiarch{$_}
+          = $self->host_variables->{$_}{DEB_HOST_MULTIARCH}
+          for keys %{$self->host_variables};
+
+        return \%deb_host_multiarch;
+    }
+);
+
+# The list of directories searched by default by the dynamic linker.
+# Packages installing shared libraries into these directories must call
+# ldconfig, must have shlibs files, and must ensure those libraries have
+# proper SONAMEs.
+#
+# Directories listed here must not have leading slashes.
+#
+# On the topic of multi-arch dirs.  Hopefully including the ones not
+# native to the local platform won't hurt.
+#
+# See Bug#469301 and Bug#464796 for more details.
+#
+has ldconfig_folders => (
+    is => 'rw',
+    lazy => 1,
+    coerce => sub { my ($arrayref) = @_; return ($arrayref // {}); },
+    default => sub {
+        my ($self) = @_;
+
+        my @multiarch = values %{$self->deb_host_multiarch};
+        my @ldconfig_folders = map { ("lib/$_", "usr/lib/$_") } @multiarch;
+
+        my @always = qw{
+          lib
+          lib32
+          lib64
+          libx32
+          usr/lib
+          usr/lib32
+          usr/lib64
+          usr/libx32
+          usr/local/lib
+        };
+        push(@ldconfig_folders, @always);
+
+        my @with_slash = map { $_ . $SLASH } @ldconfig_folders;
+
+        return \@with_slash;
+    }
+);
+
+# Valid architecture wildcards.
+has wildcards => (
+    is => 'rw',
+    lazy => 1,
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub {
+        my ($self) = @_;
+
+        my %wildcards;
+
+        for my $hyphenated (keys %{$self->host_variables}) {
+
+            my $variables = $self->host_variables->{$hyphenated};
+
+            # NB: "$os-$cpu" is not always equal to $hyphenated
+            my $abi = $variables->{DEB_HOST_ARCH_ABI};
+            my $libc = $variables->{DEB_HOST_ARCH_LIBC};
+            my $os = $variables->{DEB_HOST_ARCH_OS};
+            my $cpu = $variables->{DEB_HOST_ARCH_CPU};
+
+   # map $os-any (e.g. "linux-any") and any-$architecture (e.g. "any-amd64") to
+   # the relevant architectures.
+            $wildcards{'any'}{$hyphenated} = 1;
+
+            $wildcards{'any-any'}{$hyphenated} = 1;
+            $wildcards{"any-$cpu"}{$hyphenated} = 1;
+            $wildcards{"$os-any"}{$hyphenated} = 1;
+
+            $wildcards{'any-any-any'}{$hyphenated} = 1;
+            $wildcards{"any-any-$cpu"}{$hyphenated} = 1;
+            $wildcards{"any-$os-any"}{$hyphenated} = 1;
+            $wildcards{"any-$os-$cpu"}{$hyphenated} = 1;
+            $wildcards{"$libc-any-any"}{$hyphenated} = 1;
+            $wildcards{"$libc-any-$cpu"}{$hyphenated} = 1;
+            $wildcards{"$libc-$os-any"}{$hyphenated} = 1;
+
+            $wildcards{'any-any-any-any'}{$hyphenated} = 1;
+            $wildcards{"any-any-any-$cpu"}{$hyphenated} = 1;
+            $wildcards{"any-any-$os-any"}{$hyphenated} = 1;
+            $wildcards{"any-any-$os-$cpu"}{$hyphenated} = 1;
+            $wildcards{"any-$libc-any-any"}{$hyphenated} = 1;
+            $wildcards{"any-$libc-any-$cpu"}{$hyphenated} = 1;
+            $wildcards{"any-$libc-$os-any"}{$hyphenated} = 1;
+            $wildcards{"any-$libc-$os-$cpu"}{$hyphenated} = 1;
+            $wildcards{"$abi-any-any-any"}{$hyphenated} = 1;
+            $wildcards{"$abi-any-any-$cpu"}{$hyphenated} = 1;
+            $wildcards{"$abi-any-$os-any"}{$hyphenated} = 1;
+            $wildcards{"$abi-any-$os-$cpu"}{$hyphenated} = 1;
+            $wildcards{"$abi-$libc-any-any"}{$hyphenated} = 1;
+            $wildcards{"$abi-$libc-any-$cpu"}{$hyphenated} = 1;
+            $wildcards{"$abi-$libc-$os-any"}{$hyphenated} = 1;
+        }
+
+        return \%wildcards;
+    }
+);
+
+# Maps aliases to the "original" arch name.
+# (e.g. "linux-amd64" => "amd64")
+has names => (
+    is => 'rw',
+    lazy => 1,
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub {
+        my ($self) = @_;
+
+        my %names;
+
+        for my $hyphenated (keys %{$self->host_variables}) {
+
+            my $variables = $self->host_variables->{$hyphenated};
+
+            $names{$hyphenated} = $hyphenated;
+
+            # NB: "$os-$cpu" ne $hyphenated in some cases
+            my $os = $variables->{DEB_HOST_ARCH_OS};
+            my $cpu = $variables->{DEB_HOST_ARCH_CPU};
+
+            if ($os eq 'linux') {
+
+                # Per Policy section 11.1 (3.9.3):
+                #
+                #"""[architecture] strings are in the format "os-arch", though
+                # the OS part is sometimes elided, as when the OS is Linux."""
+                #
+                # i.e. "linux-amd64" and "amd64" are aliases, so handle them
+                # as such.  Currently, dpkg-architecture -L gives us "amd64"
+                # but in case it changes to "linux-amd64", we are prepared.
+
+                if ($hyphenated =~ /^linux-/) {
+                    # It may be temping to use $cpu here, but it does not work
+                    # for (e.g.) arm based architectures.  Instead extract the
+                    # "short" architecture name from $hyphenated
+                    my (undef, $short) = split(/-/, $hyphenated, 2);
+                    $names{$short} = $hyphenated;
+
+                } else {
+                    # short string in $hyphenated
+                    my $long = "$os-$hyphenated";
+                    $names{$long} = $hyphenated;
+                }
+            }
+        }
+
+        return \%names;
+    }
+);
+
+=item is_wildcard ($wildcard)
+
+Returns a truth value if $wildcard is a known architecture wildcard.
+
+Note: 'any' is considered a wildcard and not an architecture.
+
+=cut
+
+sub is_wildcard {
+    my ($self, $wildcard) = @_;
+
+    return exists $self->wildcards->{$wildcard};
+}
+
+=item is_release_architecture ($architecture)
+
+Returns a truth value if $architecture is (an alias of) a Debian machine
+architecture.  It returns a false value for
+architecture wildcards (including "any") and unknown architectures.
+
+=cut
+
+sub is_release_architecture {
+    my ($self, $architecture) = @_;
+
+    return exists $self->names->{$architecture};
+}
+
+=item expand_wildcard ($wildcard)
+
+Returns a list of architectures that this wildcard expands to.  No
+order is guaranteed (even between calls).  Returned values must not be
+modified.
+
+Note: This list is based on the architectures in Lintian's data file.
+However, many of these are not supported or used in Debian or any of
+its derivatives.
+
+The returned values matches the list generated by dpkg-architecture -L,
+so the returned list may use (e.g.) "amd64" for "linux-amd64".
+
+=cut
+
+sub expand_wildcard {
+    my ($self, $wildcard) = @_;
+
+    return keys %{ $self->wildcards->{$wildcard} // {} };
+}
+
+=item wildcard_includes ($wildcard, $architecture)
+
+Returns a truth value if $architecture is included in the list of
+architectures that $wildcard expands to.
+
+This is generally faster than
+
+  grep { $_ eq $architecture } expand_arch_wildcard ($wildcard)
+
+It also properly handles cases like "linux-amd64" and "amd64" being
+aliases.
+
+=cut
+
+sub wildcard_includes {
+    my ($self, $wildcard, $architecture) = @_;
+
+    $architecture = $self->names->{$architecture}
+      if exists $self->names->{$architecture};
+
+    return exists $self->wildcards->{$wildcard}{$architecture};
+}
+
+=item valid_restriction
+
+=cut
+
+sub valid_restriction {
+    my ($self, $restriction) = @_;
+
+    # strip any negative prefix
+    $restriction =~ s/^!//;
+
+    return
+      $self->is_release_architecture($restriction)
+      || $self->is_wildcard($restriction)
+      || $restriction eq 'all';
+}
+
+=item restriction_matches
+
+=cut
+
+sub restriction_matches {
+    my ($self, $restriction, $architecture) = @_;
+
+    # look for negative prefix and strip
+    my $match_wanted = !($restriction =~ s/^!//);
+
+    return $match_wanted
+      if $restriction eq $architecture;
+
+    return $match_wanted
+      if $self->is_wildcard($restriction)
+      && $self->wildcard_includes($restriction, $architecture);
+
+    return !$match_wanted;
+}
+
+=item load
+
+=cut
+
+sub load {
+    my ($self, $search_space, $our_vendor) = @_;
+
+    my @candidates = map { $_ . $SLASH . $self->location } @{$search_space};
+    my $path = first_value { -e } @candidates;
+
+    my $host_variables;
+
+    return 0
+      unless $self->read_file($path, \$host_variables);
+
+    $self->host_variables($host_variables);
+
+    return 1;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    local $ENV{LC_ALL} = 'C';
+    delete local $ENV{DEB_HOST_ARCH};
+
+    my @architectures
+      = split(/\n/, decode_utf8(safe_qx(qw{dpkg-architecture --list-known})));
+    chomp for @architectures;
+
+    my %host_variables;
+    for my $architecture (@architectures) {
+
+        my @lines= split(
+            /\n/,
+            decode_utf8(
+                safe_qx(qw{dpkg-architecture --host-arch}, $architecture)
+            )
+        );
+
+        for my $line (@lines) {
+            my ($key, $value) = split(/=/, $line, 2);
+
+            $host_variables{$architecture}{$key} = $value
+              if $key =~ /^DEB_HOST_/;
+        }
+    }
+
+    $self->cargo('host_variables');
+
+    my $data_path = "$basedir/" . $self->location;
+    my $status
+      = $self->write_file($HOST_VARIABLES, \%host_variables, $data_path);
+
+    return $status;
+}
+
+=back
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Archive/AutoRejection.pm b/lib/Lintian/Data/Archive/AutoRejection.pm
new file mode 100644
index 0000000..d05ae51
--- /dev/null
+++ b/lib/Lintian/Data/Archive/AutoRejection.pm
@@ -0,0 +1,154 @@
+# -*- perl -*-
+#
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Archive::AutoRejection;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(carp);
+use Const::Fast;
+use HTTP::Tiny;
+use List::SomeUtils qw(first_value uniq);
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+use YAML::XS qw(LoadFile);
+
+const my $EMPTY => q{};
+const my $SLASH => q{/};
+
+use Moo;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Data::Archive::AutoRejection - Lintian interface to the archive's auto-rejection tags
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Archive::AutoRejection;
+
+=head1 DESCRIPTION
+
+This module provides a way to load data files for the archive's auto-rejection tags
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item title
+
+=item location
+
+=item certain
+
+=item preventable
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Archive Auto-Rejection Tags'
+);
+
+has location => (
+    is => 'rw',
+    default => 'archive/auto-rejection.yaml'
+);
+
+has certain => (is => 'rw', default => sub { [] });
+has preventable => (is => 'rw', default => sub { [] });
+
+=item load
+
+=cut
+
+sub load {
+    my ($self, $search_space, $our_vendor) = @_;
+
+    my @candidates = map { $_ . $SLASH . $self->location } @{$search_space};
+    my $path = first_value { -e } @candidates;
+
+    unless (length $path) {
+        carp encode_utf8('Unknown data file: ' . $self->location);
+        return;
+    }
+
+    my $yaml = LoadFile($path);
+    die encode_utf8('Could not parse YAML file ' . $self->location)
+      unless defined $yaml;
+
+    my $base = $yaml->{lintian};
+    die encode_utf8('Could not parse document base for ' . $self->location)
+      unless defined $base;
+
+    my @certain = uniq @{ $base->{fatal} // [] };
+    my @preventable = uniq @{ $base->{nonfatal} // [] };
+
+    $self->certain(\@certain);
+    $self->preventable(\@preventable);
+
+    return;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    my $auto_rejection_url
+      = 'https://ftp-master.debian.org/static/lintian.tags';
+
+    my $response = HTTP::Tiny->new->get($auto_rejection_url);
+    die encode_utf8("Failed to get $auto_rejection_url!\n")
+      unless $response->{success};
+
+    my $auto_rejection_yaml = $response->{content};
+
+    my $data_path = "$basedir/" . $self->location;
+    my $parent_dir = path($data_path)->parent->stringify;
+    path($parent_dir)->mkpath
+      unless -e $parent_dir;
+
+    # already in UTF-8
+    path($data_path)->spew($auto_rejection_yaml);
+
+    return 1;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Archive/Sections.pm b/lib/Lintian/Data/Archive/Sections.pm
new file mode 100644
index 0000000..24a99c7
--- /dev/null
+++ b/lib/Lintian/Data/Archive/Sections.pm
@@ -0,0 +1,133 @@
+# -*- perl -*-
+#
+# Copyright (C) 2021 Felix Lechner
+# Copyright (C) 2022 Axel Beckert
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Archive::Sections;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(carp);
+use Const::Fast;
+use HTTP::Tiny;
+use List::SomeUtils qw(first_value uniq);
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+use Lintian::Deb822;
+
+const my $EMPTY => q{};
+const my $SLASH => q{/};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::JoinedLines';
+
+=head1 NAME
+
+Lintian::Data::Archive::Sections - Lintian interface to the archive's sections
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Archive::Sections;
+
+=head1 DESCRIPTION
+
+This module provides a way to load the data file for the archive's section.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item title
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Archive Sections'
+);
+
+=item location
+
+=cut
+
+has location => (
+    is => 'rw',
+    default => 'fields/archive-sections'
+);
+
+=item separator
+
+=cut
+
+has separator => (is => 'rw');
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    my $sections_url = 'https://metadata.ftp-master.debian.org/sections.822';
+
+    my $response = HTTP::Tiny->new->get($sections_url);
+    die encode_utf8("Failed to get $sections_url!\n")
+      unless $response->{success};
+
+    my $sections_822 = $response->{content};
+
+    # TODO: We should probably save this in the original format and
+    # parse it with Lintian::Deb822 at some time.
+    my $sections = join("\n",
+        map { s/^Section: //r }
+          grep { m{^Section: [^/]*$} }
+          split(/\n/, $sections_822))
+      ."\n";
+
+    my $data_path = "$basedir/" . $self->location;
+    my $parent_dir = path($data_path)->parent->stringify;
+    path($parent_dir)->mkpath
+      unless -e $parent_dir;
+
+    # already in UTF-8
+    path($data_path)->spew($sections);
+
+    return 1;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Axel Beckert <abe@debian.org> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Authorities.pm b/lib/Lintian/Data/Authorities.pm
new file mode 100644
index 0000000..fdb77cd
--- /dev/null
+++ b/lib/Lintian/Data/Authorities.pm
@@ -0,0 +1,330 @@
+# Copyright (C) 2011 Niels Thykier <niels@thykier.net>
+# Copyright (C) 2018 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Data::Authorities;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Lintian::Data::Authority::DebconfSpecification;
+use Lintian::Data::Authority::DebianPolicy;
+use Lintian::Data::Authority::DeveloperReference;
+use Lintian::Data::Authority::DocBaseManual;
+use Lintian::Data::Authority::FilesystemHierarchy;
+use Lintian::Data::Authority::JavaPolicy;
+use Lintian::Data::Authority::LintianManual;
+use Lintian::Data::Authority::MenuPolicy;
+use Lintian::Data::Authority::MenuManual;
+use Lintian::Data::Authority::NewMaintainer;
+use Lintian::Data::Authority::PerlPolicy;
+use Lintian::Data::Authority::PythonPolicy;
+use Lintian::Data::Authority::VimPolicy;
+
+const my $EMPTY => q{};
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Data::Authorities - Lintian's Reference Authorities
+
+=head1 SYNOPSIS
+
+ my $data = Lintian::Data->new;
+
+=head1 DESCRIPTION
+
+Lintian::Data::Authorities handles finding, parsing and implementation of Lintian reference authorities
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item markdown_authority_reference
+
+=cut
+
+sub markdown_authority_reference {
+    my ($self, $volume, $section) = @_;
+
+    my @MARKDOWN_CAPABLE = (
+        $self->new_maintainer,$self->menu_policy,
+        $self->perl_policy,$self->python_policy,
+        $self->java_policy,$self->vim_policy,
+        $self->lintian_manual,$self->developer_reference,
+        $self->policy_manual,$self->debconf_specification,
+        $self->menu_manual,$self->doc_base_manual,
+        $self->filesystem_hierarchy_standard,
+    );
+
+    my %by_shorthand = map { $_->shorthand => $_ } @MARKDOWN_CAPABLE;
+
+    return $EMPTY
+      unless exists $by_shorthand{$volume};
+
+    my $manual = $by_shorthand{$volume};
+
+    return $manual->markdown_citation($section);
+}
+
+=item debconf_specification
+
+=cut
+
+has debconf_specification => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $manual = Lintian::Data::Authority::DebconfSpecification->new;
+        $manual->load($self->data_paths, $self->vendor);
+
+        return $manual;
+    }
+);
+
+=item developer_reference
+
+=cut
+
+has developer_reference => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $manual = Lintian::Data::Authority::DeveloperReference->new;
+        $manual->load($self->data_paths, $self->vendor);
+
+        return $manual;
+    }
+);
+
+=item doc_base_manual
+
+=cut
+
+has doc_base_manual => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $manual = Lintian::Data::Authority::DocBaseManual->new;
+        $manual->load($self->data_paths, $self->vendor);
+
+        return $manual;
+    }
+);
+
+=item filesystem_hierarchy_standard
+
+=cut
+
+has filesystem_hierarchy_standard => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $manual= Lintian::Data::Authority::FilesystemHierarchy->new;
+        $manual->load($self->data_paths, $self->vendor);
+
+        return $manual;
+    }
+);
+
+=item java_policy
+
+=cut
+
+has java_policy => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $manual = Lintian::Data::Authority::JavaPolicy->new;
+        $manual->load($self->data_paths, $self->vendor);
+
+        return $manual;
+    }
+);
+
+=item lintian_manual
+
+=cut
+
+has lintian_manual => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $manual = Lintian::Data::Authority::LintianManual->new;
+        $manual->load($self->data_paths, $self->vendor);
+
+        return $manual;
+    }
+);
+
+=item menu_manual
+
+=cut
+
+has menu_manual => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $manual = Lintian::Data::Authority::MenuManual->new;
+        $manual->load($self->data_paths, $self->vendor);
+
+        return $manual;
+    }
+);
+
+=item menu_policy
+
+=cut
+
+has menu_policy => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $manual = Lintian::Data::Authority::MenuPolicy->new;
+        $manual->load($self->data_paths, $self->vendor);
+
+        return $manual;
+    }
+);
+
+=item menu_policy
+
+=cut
+
+has new_maintainer => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $manual = Lintian::Data::Authority::NewMaintainer->new;
+        $manual->load($self->data_paths, $self->vendor);
+
+        return $manual;
+    }
+);
+
+=item perl_policy
+
+=cut
+
+has perl_policy => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $manual = Lintian::Data::Authority::PerlPolicy->new;
+        $manual->load($self->data_paths, $self->vendor);
+
+        return $manual;
+    }
+);
+
+=item policy_manual
+
+=cut
+
+has policy_manual => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $manual = Lintian::Data::Authority::DebianPolicy->new;
+        $manual->load($self->data_paths, $self->vendor);
+
+        return $manual;
+    }
+);
+
+=item python_policy
+
+=cut
+
+has python_policy => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $manual = Lintian::Data::Authority::PythonPolicy->new;
+        $manual->load($self->data_paths, $self->vendor);
+
+        return $manual;
+    }
+);
+
+=item vim_policy
+
+=cut
+
+has vim_policy => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $manual = Lintian::Data::Authority::VimPolicy->new;
+        $manual->load($self->data_paths, $self->vendor);
+
+        return $manual;
+    }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Authority/DebconfSpecification.pm b/lib/Lintian/Data/Authority/DebconfSpecification.pm
new file mode 100644
index 0000000..661d11e
--- /dev/null
+++ b/lib/Lintian/Data/Authority/DebconfSpecification.pm
@@ -0,0 +1,328 @@
+# -*- perl -*-
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2001 Colin Watson
+# Copyright (C) 2008 Jorda Polo
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Authority::DebconfSpecification;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use File::Basename qw(dirname);
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+use WWW::Mechanize ();
+
+use Lintian::Output::Markdown qw(markdown_authority);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $COLON => q{:};
+const my $UNDERSCORE => q{_};
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+const my $TWO_PARTS => 2;
+
+const my $VOLUME_KEY => $UNDERSCORE;
+const my $SEPARATOR => $COLON x 2;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::JoinedLines';
+
+=head1 NAME
+
+Lintian::Data::Authority::DebconfSpecification - Lintian interface for manual references
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Authority::DebconfSpecification;
+
+=head1 DESCRIPTION
+
+Lintian::Data::Authority::DebconfSpecification provides a way to load data files for
+manual references.
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item title
+
+=item shorthand
+
+=item location
+
+=item separator
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Debconf Specification'
+);
+
+has shorthand => (
+    is => 'rw',
+    default => 'debconf-specification'
+);
+
+has location => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return 'authority/' . $self->shorthand;
+    }
+);
+
+has separator => (
+    is => 'rw',
+    default => sub { qr/::/ }
+);
+
+=item consumer
+
+=cut
+
+sub consumer {
+    my ($self, $key, $remainder, $previous) = @_;
+
+    return undef
+      if defined $previous;
+
+    my ($title, $url)= split($self->separator, $remainder, $TWO_PARTS);
+
+    my %entry;
+    $entry{title} = $title;
+    $entry{url} = $url;
+
+    return \%entry;
+}
+
+=item markdown_citation
+
+=cut
+
+sub markdown_citation {
+    my ($self, $section_key) = @_;
+
+    croak "Invalid section $section_key"
+      if $section_key eq $VOLUME_KEY;
+
+    my $volume_entry = $self->value($VOLUME_KEY);
+
+    # start with the citation to the overall manual.
+    my $volume_title = $volume_entry->{title};
+    my $volume_url   = $volume_entry->{url};
+
+    my $section_title;
+    my $section_url;
+
+    if ($self->recognizes($section_key)) {
+
+        my $section_entry = $self->value($section_key);
+
+        $section_title = $section_entry->{title};
+        $section_url   = $section_entry->{url};
+    }
+
+    return markdown_authority(
+        $volume_title, $volume_url,$section_key,
+        $section_title, $section_url
+    );
+}
+
+=item write_line
+
+=cut
+
+sub write_line {
+    my ($data_fd, $section_key, $section_title, $destination) = @_;
+
+    # drop final dots
+    $section_key =~ s{ [.]+ $}{}x;
+
+    # reduce consecutive whitespace
+    $section_title =~ s{ \s+ }{ }gx;
+
+    my $line= join($SEPARATOR,$section_key, $section_title, $destination);
+
+    say {$data_fd} encode_utf8($line);
+
+    return;
+}
+
+=item write_data_file
+
+=cut
+
+sub write_data_file {
+    my ($self, $basedir, $generated) = @_;
+
+    my $header =<<"HEADER";
+# Data about titles, sections, and URLs of manuals, used to expand references
+# in tag descriptions and add links for HTML output.  Each line of this file
+# has three fields separated by double colons:
+#
+#     <section> :: <title> :: <url>
+#
+# If <section> is an underscore, that line specifies the title and URL for the
+# whole manual.
+
+HEADER
+
+    my $data_path = "$basedir/" . $self->location;
+    my $parent_dir = path($data_path)->parent->stringify;
+    path($parent_dir)->mkpath
+      unless -e $parent_dir;
+
+    my $output = encode_utf8($header) . $generated;
+    path($data_path)->spew($output);
+
+    return;
+}
+
+=item extract_sections_from_links
+
+=cut
+
+sub extract_sections_from_links {
+    my ($self, $data_fd, $base_url, $page_name)= @_;
+
+    my $page_url = $base_url . $page_name;
+
+    my $mechanize = WWW::Mechanize->new();
+    $mechanize->get($page_url);
+
+    my $page_title = $mechanize->title;
+
+    # strip explanatory remark
+    $page_title =~ s{ \s* \N{EM DASH} .* $}{}x;
+
+    # underscore is a token for the whole page
+    write_line($data_fd, $VOLUME_KEY, $page_title, $page_url);
+
+    my %by_section_key;
+    my $in_appendix = 0;
+
+    # https://stackoverflow.com/a/254687
+    for my $link ($mechanize->links) {
+
+        next
+          unless length $link->text;
+
+        next
+          if $link->text !~ qr{^ \s* ([.\d]+) \s+ (.+) $}x;
+
+        my $section_key = $1;
+        my $section_title = $2;
+
+        # drop final dots
+        $section_key =~ s{ [.]+ $}{}x;
+
+        # reduce consecutive whitespace
+        $section_title =~ s{ \s+ }{ }gx;
+
+        my $relative_destination = $link->url;
+
+        my $destination_base = $page_url;
+        $destination_base = dirname($page_url) . $SLASH
+          unless $destination_base =~ m{ / $}x
+          || $relative_destination =~ m{^ [#] }x;
+
+        my $full_destination = $destination_base . $relative_destination;
+
+        next
+          if exists $by_section_key{$section_key}
+          && ( $by_section_key{$section_key}{title} eq $section_title
+            || $by_section_key{$section_key}{destination} eq$full_destination);
+
+        # Some manuals reuse section numbers for different references,
+        # e.g. the Debian Policy's normal and appendix sections are
+        # numbers that clash with each other. Track if we've already
+        # seen a section pointing to some other URL than the current one,
+        # and prepend it with an indicator
+        $in_appendix = 1
+          if exists $by_section_key{$section_key}
+          && $by_section_key{$section_key}{destination} ne$full_destination;
+
+        $section_key = "appendix-$section_key"
+          if $in_appendix;
+
+        $by_section_key{$section_key}{title} = $section_title;
+        $by_section_key{$section_key}{destination} = $full_destination;
+
+        write_line($data_fd, $section_key, $section_title, $full_destination);
+    }
+
+    return;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    # single page
+    my $base_url = 'https://www.debian.org/doc/packaging-manuals/';
+    my $index_name = 'debconf_specification.html';
+
+    my $generated;
+    open(my $memory_fd, '>', \$generated)
+      or die encode_utf8('Cannot open scalar');
+
+    $self->extract_sections_from_links($memory_fd, $base_url, $index_name);
+
+    close $memory_fd;
+
+    $self->write_data_file($basedir, $generated);
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Authority/DebianPolicy.pm b/lib/Lintian/Data/Authority/DebianPolicy.pm
new file mode 100644
index 0000000..177b07d
--- /dev/null
+++ b/lib/Lintian/Data/Authority/DebianPolicy.pm
@@ -0,0 +1,321 @@
+# -*- perl -*-
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2001 Colin Watson
+# Copyright (C) 2008 Jorda Polo
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Authority::DebianPolicy;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+use WWW::Mechanize ();
+
+use Lintian::Output::Markdown qw(markdown_authority);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $COLON => q{:};
+const my $UNDERSCORE => q{_};
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+const my $TWO_PARTS => 2;
+
+const my $VOLUME_KEY => $UNDERSCORE;
+const my $SEPARATOR => $COLON x 2;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::JoinedLines';
+
+=head1 NAME
+
+Lintian::Data::Authority::DebianPolicy - Lintian interface for manual references
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Authority::DebianPolicy;
+
+=head1 DESCRIPTION
+
+Lintian::Data::Authority::DebianPolicy provides a way to load data files for
+manual references.
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item title
+
+=item shorthand
+
+=item location
+
+=item separator
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Debian Policy'
+);
+
+has shorthand => (
+    is => 'rw',
+    default => 'debian-policy'
+);
+
+has location => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return 'authority/' . $self->shorthand;
+    }
+);
+
+has separator => (
+    is => 'rw',
+    default => sub { qr/::/ }
+);
+
+=item consumer
+
+=cut
+
+sub consumer {
+    my ($self, $key, $remainder, $previous) = @_;
+
+    return undef
+      if defined $previous;
+
+    my ($title, $url)= split($self->separator, $remainder, $TWO_PARTS);
+
+    my %entry;
+    $entry{title} = $title;
+    $entry{url} = $url;
+
+    return \%entry;
+}
+
+=item markdown_citation
+
+=cut
+
+sub markdown_citation {
+    my ($self, $section_key) = @_;
+
+    croak "Invalid section $section_key"
+      if $section_key eq $VOLUME_KEY;
+
+    my $volume_entry = $self->value($VOLUME_KEY);
+
+    # start with the citation to the overall manual.
+    my $volume_title = $volume_entry->{title};
+    my $volume_url   = $volume_entry->{url};
+
+    my $section_title;
+    my $section_url;
+
+    if ($self->recognizes($section_key)) {
+
+        my $section_entry = $self->value($section_key);
+
+        $section_title = $section_entry->{title};
+        $section_url   = $section_entry->{url};
+    }
+
+    return markdown_authority(
+        $volume_title, $volume_url,$section_key,
+        $section_title, $section_url
+    );
+}
+
+=item write_line
+
+=cut
+
+sub write_line {
+    my ($data_fd, $section_key, $section_title, $destination) = @_;
+
+    # drop final dots
+    $section_key =~ s{ [.]+ $}{}x;
+
+    # reduce consecutive whitespace
+    $section_title =~ s{ \s+ }{ }gx;
+
+    my $line= join($SEPARATOR,$section_key, $section_title, $destination);
+
+    say {$data_fd} encode_utf8($line);
+
+    return;
+}
+
+=item write_data_file
+
+=cut
+
+sub write_data_file {
+    my ($self, $basedir, $generated) = @_;
+
+    my $header =<<"HEADER";
+# Data about titles, sections, and URLs of manuals, used to expand references
+# in tag descriptions and add links for HTML output.  Each line of this file
+# has three fields separated by double colons:
+#
+#     <section> :: <title> :: <url>
+#
+# If <section> is an underscore, that line specifies the title and URL for the
+# whole manual.
+
+HEADER
+
+    my $data_path = "$basedir/" . $self->location;
+    my $parent_dir = path($data_path)->parent->stringify;
+    path($parent_dir)->mkpath
+      unless -e $parent_dir;
+
+    my $output = encode_utf8($header) . $generated;
+    path($data_path)->spew($output);
+
+    return;
+}
+
+=item extract_sections_from_links
+
+=cut
+
+sub extract_sections_from_links {
+    my ($self, $data_fd, $base_url)= @_;
+
+    my $mechanize = WWW::Mechanize->new();
+    $mechanize->get($base_url);
+
+    my $page_title = $mechanize->title;
+
+    # strip explanatory remark
+    $page_title =~ s{ \s* \N{EM DASH} .* $}{}x;
+
+    # underscore is a token for the whole page
+    write_line($data_fd, $VOLUME_KEY, $page_title, $base_url);
+
+    my %by_section_key;
+    my $in_appendix = 0;
+
+    # https://stackoverflow.com/a/254687
+    for my $link ($mechanize->links) {
+
+        next
+          unless length $link->text;
+
+        next
+          if $link->text !~ qr{^ \s* ([.\d]+) \s+ (.+) $}x;
+
+        my $section_key = $1;
+        my $section_title = $2;
+
+        # drop final dots
+        $section_key =~ s{ [.]+ $}{}x;
+
+        # reduce consecutive whitespace
+        $section_title =~ s{ \s+ }{ }gx;
+
+        my $destination = $base_url . $link->url;
+
+        next
+          if exists $by_section_key{$section_key}
+          && ( $by_section_key{$section_key}{title} eq $section_title
+            || $by_section_key{$section_key}{destination} eq $destination);
+
+        # Some manuals reuse section numbers for different references,
+        # e.g. the Debian Policy's normal and appendix sections are
+        # numbers that clash with each other. Track if we've already
+        # seen a section pointing to some other URL than the current one,
+        # and prepend it with an indicator
+        $in_appendix = 1
+          if exists $by_section_key{$section_key}
+          && $by_section_key{$section_key}{destination} ne $destination;
+
+        $section_key = "appendix-$section_key"
+          if $in_appendix;
+
+        # do not collect the upgrading checklists in appendix 10 of policy
+        # the numbering changes all the time
+        next
+          if $section_key =~ m{^ appendix-10 [.] }x;
+
+        $by_section_key{$section_key}{title} = $section_title;
+        $by_section_key{$section_key}{destination} = $destination;
+
+        write_line($data_fd, $section_key, $section_title, $destination);
+    }
+
+    return;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    my $base_url = 'https://www.debian.org/doc/debian-policy/';
+
+    my $generated;
+    open(my $memory_fd, '>', \$generated)
+      or die encode_utf8('Cannot open scalar');
+
+    $self->extract_sections_from_links($memory_fd, $base_url);
+
+    close $memory_fd;
+
+    $self->write_data_file($basedir, $generated);
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Authority/DeveloperReference.pm b/lib/Lintian/Data/Authority/DeveloperReference.pm
new file mode 100644
index 0000000..676cbf4
--- /dev/null
+++ b/lib/Lintian/Data/Authority/DeveloperReference.pm
@@ -0,0 +1,319 @@
+# -*- perl -*-
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2001 Colin Watson
+# Copyright (C) 2008 Jorda Polo
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Authority::DeveloperReference;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+use WWW::Mechanize ();
+
+use Lintian::Output::Markdown qw(markdown_authority);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $COLON => q{:};
+const my $UNDERSCORE => q{_};
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+const my $TWO_PARTS => 2;
+
+const my $VOLUME_KEY => $UNDERSCORE;
+const my $SEPARATOR => $COLON x 2;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::JoinedLines';
+
+=head1 NAME
+
+Lintian::Data::Authority::DeveloperReference - Lintian interface for manual references
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Authority::DeveloperReference;
+
+=head1 DESCRIPTION
+
+Lintian::Data::Authority::DeveloperReference provides a way to load data files for
+manual references.
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item title
+
+=item shorthand
+
+=item location
+
+=item separator
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => q{Developer's Reference}
+);
+
+has shorthand => (
+    is => 'rw',
+    default => 'developer-reference'
+);
+
+has location => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return 'authority/' . $self->shorthand;
+    }
+);
+
+has separator => (
+    is => 'rw',
+    default => sub { qr/::/ }
+);
+
+=item consumer
+
+=cut
+
+sub consumer {
+    my ($self, $key, $remainder, $previous) = @_;
+
+    return undef
+      if defined $previous;
+
+    my ($title, $url)= split($self->separator, $remainder, $TWO_PARTS);
+
+    my %entry;
+    $entry{title} = $title;
+    $entry{url} = $url;
+
+    return \%entry;
+}
+
+=item markdown_citation
+
+=cut
+
+sub markdown_citation {
+    my ($self, $section_key) = @_;
+
+    croak "Invalid section $section_key"
+      if $section_key eq $VOLUME_KEY;
+
+    my $volume_entry = $self->value($VOLUME_KEY);
+
+    # start with the citation to the overall manual.
+    my $volume_title = $volume_entry->{title};
+    my $volume_url   = $volume_entry->{url};
+
+    my $section_title;
+    my $section_url;
+
+    if ($self->recognizes($section_key)) {
+
+        my $section_entry = $self->value($section_key);
+
+        $section_title = $section_entry->{title};
+        $section_url   = $section_entry->{url};
+    }
+
+    return markdown_authority(
+        $volume_title, $volume_url,$section_key,
+        $section_title, $section_url
+    );
+}
+
+=item write_line
+
+=cut
+
+sub write_line {
+    my ($data_fd, $section_key, $section_title, $destination) = @_;
+
+    # drop final dots
+    $section_key =~ s{ [.]+ $}{}x;
+
+    # reduce consecutive whitespace
+    $section_title =~ s{ \s+ }{ }gx;
+
+    my $line= join($SEPARATOR,$section_key, $section_title, $destination);
+
+    say {$data_fd} encode_utf8($line);
+
+    return;
+}
+
+=item write_data_file
+
+=cut
+
+sub write_data_file {
+    my ($self, $basedir, $generated) = @_;
+
+    my $header =<<"HEADER";
+# Data about titles, sections, and URLs of manuals, used to expand references
+# in tag descriptions and add links for HTML output.  Each line of this file
+# has three fields separated by double colons:
+#
+#     <section> :: <title> :: <url>
+#
+# If <section> is an underscore, that line specifies the title and URL for the
+# whole manual.
+
+HEADER
+
+    my $data_path = "$basedir/" . $self->location;
+    my $parent_dir = path($data_path)->parent->stringify;
+    path($parent_dir)->mkpath
+      unless -e $parent_dir;
+
+    my $output = encode_utf8($header) . $generated;
+    path($data_path)->spew($output);
+
+    return;
+}
+
+=item extract_sections_from_links
+
+=cut
+
+sub extract_sections_from_links {
+    my ($self, $data_fd, $base_url)= @_;
+
+    my $mechanize = WWW::Mechanize->new();
+    $mechanize->get($base_url);
+
+    my $page_title = $mechanize->title;
+
+    # strip explanatory remark
+    $page_title =~ s{ \s* \N{EM DASH} .* $}{}x;
+
+    # underscore is a token for the whole page
+    write_line($data_fd, $VOLUME_KEY, $page_title, $base_url);
+
+    my %by_section_key;
+    my $in_appendix = 0;
+
+    # https://stackoverflow.com/a/254687
+    for my $link ($mechanize->links) {
+
+        next
+          unless length $link->text;
+
+        next
+          if $link->text !~ qr{^ \s* ([.\d]+) \s+ (.+) $}x;
+
+        my $section_key = $1;
+        my $section_title = $2;
+
+        # drop final dots
+        $section_key =~ s{ [.]+ $}{}x;
+
+        # reduce consecutive whitespace
+        $section_title =~ s{ \s+ }{ }gx;
+
+        my $destination = $base_url . $link->url;
+
+        # developers reference likes to return locale specific pages
+        $destination =~ s{ [.]\w{2}[.]html }{.html}x;
+
+        next
+          if exists $by_section_key{$section_key}
+          && ( $by_section_key{$section_key}{title} eq $section_title
+            || $by_section_key{$section_key}{destination} eq $destination);
+
+        # Some manuals reuse section numbers for different references,
+        # e.g. the Debian Policy's normal and appendix sections are
+        # numbers that clash with each other. Track if we've already
+        # seen a section pointing to some other URL than the current one,
+        # and prepend it with an indicator
+        $in_appendix = 1
+          if exists $by_section_key{$section_key}
+          && $by_section_key{$section_key}{destination} ne $destination;
+
+        $section_key = "appendix-$section_key"
+          if $in_appendix;
+
+        $by_section_key{$section_key}{title} = $section_title;
+        $by_section_key{$section_key}{destination} = $destination;
+
+        write_line($data_fd, $section_key, $section_title, $destination);
+    }
+
+    return;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    my $base_url = 'https://www.debian.org/doc/developers-reference/';
+
+    my $generated;
+    open(my $memory_fd, '>', \$generated)
+      or die encode_utf8('Cannot open scalar');
+
+    $self->extract_sections_from_links($memory_fd, $base_url);
+
+    close $memory_fd;
+
+    $self->write_data_file($basedir, $generated);
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Authority/DocBaseManual.pm b/lib/Lintian/Data/Authority/DocBaseManual.pm
new file mode 100644
index 0000000..53cfbcb
--- /dev/null
+++ b/lib/Lintian/Data/Authority/DocBaseManual.pm
@@ -0,0 +1,431 @@
+# -*- perl -*-
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2001 Colin Watson
+# Copyright (C) 2008 Jorda Polo
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Authority::DocBaseManual;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use File::Basename qw(dirname basename);
+use IPC::Run3;
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+use WWW::Mechanize ();
+
+use Lintian::Output::Markdown qw(markdown_authority);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $COLON => q{:};
+const my $INDENT => $SPACE x 4;
+const my $UNDERSCORE => q{_};
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+const my $TWO_PARTS => 2;
+
+const my $VOLUME_KEY => $UNDERSCORE;
+const my $SEPARATOR => $COLON x 2;
+
+const my $WAIT_STATUS_SHIFT => 8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::JoinedLines';
+
+=head1 NAME
+
+Lintian::Data::Authority::DocBaseManual - Lintian interface for manual references
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Authority::DocBaseManual;
+
+=head1 DESCRIPTION
+
+Lintian::Data::Authority::DocBaseManual provides a way to load data files for
+manual references.
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item title
+
+=item shorthand
+
+=item location
+
+=item separator
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Doc-Base Manual'
+);
+
+has shorthand => (
+    is => 'rw',
+    default => 'doc-base-manual'
+);
+
+has location => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return 'authority/' . $self->shorthand;
+    }
+);
+
+has separator => (
+    is => 'rw',
+    default => sub { qr/::/ }
+);
+
+=item consumer
+
+=cut
+
+sub consumer {
+    my ($self, $key, $remainder, $previous) = @_;
+
+    return undef
+      if defined $previous;
+
+    my ($title, $url)= split($self->separator, $remainder, $TWO_PARTS);
+
+    my %entry;
+    $entry{title} = $title;
+    $entry{url} = $url;
+
+    return \%entry;
+}
+
+=item markdown_citation
+
+=cut
+
+sub markdown_citation {
+    my ($self, $section_key) = @_;
+
+    croak "Invalid section $section_key"
+      if $section_key eq $VOLUME_KEY;
+
+    my $volume_entry = $self->value($VOLUME_KEY);
+
+    # start with the citation to the overall manual.
+    my $volume_title = $volume_entry->{title};
+    my $volume_url   = $volume_entry->{url};
+
+    my $section_title;
+    my $section_url;
+
+    if ($self->recognizes($section_key)) {
+
+        my $section_entry = $self->value($section_key);
+
+        $section_title = $section_entry->{title};
+        $section_url   = $section_entry->{url};
+    }
+
+    return markdown_authority(
+        $volume_title, $volume_url,$section_key,
+        $section_title, $section_url
+    );
+}
+
+=item write_line
+
+=cut
+
+sub write_line {
+    my ($data_fd, $section_key, $section_title, $destination) = @_;
+
+    # drop final dots
+    $section_key =~ s{ [.]+ $}{}x;
+
+    # reduce consecutive whitespace
+    $section_title =~ s{ \s+ }{ }gx;
+
+    my $line= join($SEPARATOR,$section_key, $section_title, $destination);
+
+    say {$data_fd} encode_utf8($line);
+
+    return;
+}
+
+=item write_data_file
+
+=cut
+
+sub write_data_file {
+    my ($self, $basedir, $generated) = @_;
+
+    my $header =<<"HEADER";
+# Data about titles, sections, and URLs of manuals, used to expand references
+# in tag descriptions and add links for HTML output.  Each line of this file
+# has three fields separated by double colons:
+#
+#     <section> :: <title> :: <url>
+#
+# If <section> is an underscore, that line specifies the title and URL for the
+# whole manual.
+
+HEADER
+
+    my $data_path = "$basedir/" . $self->location;
+    my $parent_dir = path($data_path)->parent->stringify;
+    path($parent_dir)->mkpath
+      unless -e $parent_dir;
+
+    my $output = encode_utf8($header) . $generated;
+    path($data_path)->spew($output);
+
+    return;
+}
+
+=item find_installable_name
+
+=cut
+
+sub find_installable_name {
+    my ($self, $archive, $port, $requested_path) = @_;
+
+    my @installed_by;
+
+    # find installable package
+    for my $installable_architecture ('all', $port) {
+
+        my $local_path
+          = $archive->contents_gz('sid', 'main', $installable_architecture);
+
+        open(my $fd, '<:gzip', $local_path)
+          or die encode_utf8("Cannot open $local_path.");
+
+        while (my $line = <$fd>) {
+
+            chomp $line;
+
+            my ($path, $finder) = split($SPACE, $line, 2);
+            next
+              unless length $path
+              && length $finder;
+
+            if ($path eq $requested_path) {
+
+                my $name = $1;
+
+                my @locations = split(m{,}, $finder);
+                for my $location (@locations) {
+
+                    my ($section, $installable)= split(m{/}, $location, 2);
+
+                    push(@installed_by, $installable);
+                }
+
+                next;
+            }
+        }
+
+        close $fd;
+    }
+
+    die encode_utf8(
+        "The path $requested_path is not installed by any package.")
+      if @installed_by < 1;
+
+    if (@installed_by > 1) {
+        warn encode_utf8(
+            "The path $requested_path is installed by multiple packages:\n");
+        warn encode_utf8($INDENT . "- $_\n")for @installed_by;
+    }
+
+    my $installable_name = shift @installed_by;
+
+    return $installable_name;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    # shipped as part of the doc-base installable
+    my $shipped_base = 'usr/share/doc/doc-base/doc-base.html/';
+    my $index_name = 'index.html';
+
+    my $shipped_path = $shipped_base . $index_name;
+    my $stored_uri = "file:///$shipped_path";
+
+    # neutral sort order
+    local $ENV{LC_ALL} = 'C';
+
+    my $port = 'amd64';
+    my $installable_name
+      = $self->find_installable_name($archive, $port, $shipped_path);
+
+    my $deb822_by_installable_name
+      = $archive->deb822_packages_by_installable_name('sid', 'main', $port);
+
+    my $work_folder
+      = Path::Tiny->tempdir(TEMPLATE => 'refresh-doc-base-manual-XXXXXXXXXX');
+
+    die encode_utf8("Installable $installable_name not shipped in port $port")
+      unless exists $deb822_by_installable_name->{$installable_name};
+
+    my $deb822 = $deb822_by_installable_name->{$installable_name};
+
+    my $pool_path = $deb822->value('Filename');
+
+    my $deb_filename = basename($pool_path);
+    my $deb_local_path = "$work_folder/$deb_filename";
+    my $deb_url = $archive->mirror_base . $SLASH . $pool_path;
+
+    my $stderr;
+    run3([qw{wget --quiet}, "--output-document=$deb_local_path", $deb_url],
+        undef, \$stderr);
+    my $status = ($? >> $WAIT_STATUS_SHIFT);
+
+    # stderr already in UTF-8
+    die $stderr
+      if $status;
+
+    my $extract_folder = "$work_folder/unpacked/$pool_path";
+    path($extract_folder)->mkpath;
+
+    run3([qw{dpkg-deb --extract}, $deb_local_path, $extract_folder],
+        undef, \$stderr);
+    $status = ($? >> $WAIT_STATUS_SHIFT);
+
+    # stderr already in UTF-8
+    die $stderr
+      if $status;
+
+    unlink($deb_local_path)
+      or die encode_utf8("Cannot delete $deb_local_path");
+
+    my $generated;
+    open(my $memory_fd, '>', \$generated)
+      or die encode_utf8('Cannot open scalar');
+
+    my $mechanize = WWW::Mechanize->new();
+
+    my $fresh_uri = URI::file->new_abs("/$extract_folder/$shipped_path");
+    $mechanize->get($fresh_uri);
+
+    my $page_title = $mechanize->title;
+
+    # strip explanatory remark
+    $page_title =~ s{ \s* \N{EM DASH} .* $}{}x;
+
+    # underscore is a token for the whole page
+    write_line($memory_fd, $VOLUME_KEY, $page_title, $stored_uri);
+
+    my %by_section_key;
+    my $in_appendix = 0;
+
+    # https://stackoverflow.com/a/254687
+    for my $link ($mechanize->links) {
+
+        next
+          unless length $link->text;
+
+        next
+          if $link->text !~ qr{^ \s* ([.\d]+) \s+ (.+) $}x;
+
+        my $section_key = $1;
+        my $section_title = $2;
+
+        # drop final dots
+        $section_key =~ s{ [.]+ $}{}x;
+
+        # reduce consecutive whitespace
+        $section_title =~ s{ \s+ }{ }gx;
+
+        my $relative_destination = $link->url;
+
+        my $destination_base = $stored_uri;
+        $destination_base = dirname($stored_uri) . $SLASH
+          unless $destination_base =~ m{ / $}x
+          || $relative_destination =~ m{^ [#] }x;
+
+        my $full_destination = $destination_base . $relative_destination;
+
+        next
+          if exists $by_section_key{$section_key}
+          && ( $by_section_key{$section_key}{title} eq $section_title
+            || $by_section_key{$section_key}{destination} eq$full_destination);
+
+        # Some manuals reuse section numbers for different references,
+        # e.g. the Debian Policy's normal and appendix sections are
+        # numbers that clash with each other. Track if we've already
+        # seen a section pointing to some other URL than the current one,
+        # and prepend it with an indicator
+        $in_appendix = 1
+          if exists $by_section_key{$section_key}
+          && $by_section_key{$section_key}{destination} ne$full_destination;
+
+        $section_key = "appendix-$section_key"
+          if $in_appendix;
+
+        $by_section_key{$section_key}{title} = $section_title;
+        $by_section_key{$section_key}{destination} = $full_destination;
+
+        write_line($memory_fd, $section_key, $section_title,$full_destination);
+    }
+
+    close $memory_fd;
+
+    $self->write_data_file($basedir, $generated);
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Authority/FilesystemHierarchy.pm b/lib/Lintian/Data/Authority/FilesystemHierarchy.pm
new file mode 100644
index 0000000..89fb677
--- /dev/null
+++ b/lib/Lintian/Data/Authority/FilesystemHierarchy.pm
@@ -0,0 +1,333 @@
+# -*- perl -*-
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2001 Colin Watson
+# Copyright (C) 2008 Jorda Polo
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Authority::FilesystemHierarchy;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use File::Basename qw(dirname);
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+use WWW::Mechanize ();
+
+use Lintian::Output::Markdown qw(markdown_authority);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $COLON => q{:};
+const my $UNDERSCORE => q{_};
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+const my $THREE_PARTS => 3;
+
+const my $VOLUME_KEY => $UNDERSCORE;
+const my $SEPARATOR => $COLON x 2;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::JoinedLines';
+
+=head1 NAME
+
+Lintian::Data::Authority::FilesystemHierarchy - Lintian interface for manual references
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Authority::FilesystemHierarchy;
+
+=head1 DESCRIPTION
+
+Lintian::Data::Authority::FilesystemHierarchy provides a way to load data files for
+manual references.
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item title
+
+=item shorthand
+
+=item location
+
+=item separator
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Filesystem Hierarchy Standard'
+);
+
+has shorthand => (
+    is => 'rw',
+    default => 'filesystem-hierarchy'
+);
+
+has location => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return 'authority/' . $self->shorthand;
+    }
+);
+
+has separator => (
+    is => 'rw',
+    default => sub { qr/::/ }
+);
+
+=item consumer
+
+=cut
+
+sub consumer {
+    my ($self, $key, $remainder, $previous) = @_;
+
+    return undef
+      if defined $previous;
+
+    my ($number, $title, $url)
+      = split($self->separator, $remainder, $THREE_PARTS);
+
+    my %entry;
+    $entry{title} = $title;
+    $entry{number} = $number;
+    $entry{url} = $url;
+
+    return \%entry;
+}
+
+=item markdown_citation
+
+=cut
+
+sub markdown_citation {
+    my ($self, $section_key) = @_;
+
+    croak "Invalid section $section_key"
+      if $section_key eq $VOLUME_KEY;
+
+    my $volume_entry = $self->value($VOLUME_KEY);
+
+    # start with the citation to the overall manual.
+    my $volume_title = $volume_entry->{title};
+    my $volume_url   = $volume_entry->{url};
+
+    my $section_title;
+    my $section_number;
+    my $section_url;
+
+    if ($self->recognizes($section_key)) {
+
+        my $section_entry = $self->value($section_key);
+
+        $section_title = $section_entry->{title};
+        $section_number = $section_entry->{number};
+        $section_url = $section_entry->{url};
+    }
+
+    return markdown_authority(
+        $volume_title, $volume_url,$section_number,
+        $section_title, $section_url
+    );
+}
+
+=item write_line
+
+=cut
+
+sub write_line {
+    my ($data_fd, $section_key, $section_number, $section_title, $destination)
+      = @_;
+
+    # drop final dots
+    $section_key =~ s{ [.]+ $}{}x;
+
+    # reduce consecutive whitespace
+    $section_title =~ s{ \s+ }{ }gx;
+
+    my $line= join($SEPARATOR,
+        $section_key, $section_number, $section_title, $destination);
+
+    say {$data_fd} encode_utf8($line);
+
+    return;
+}
+
+=item write_data_file
+
+=cut
+
+sub write_data_file {
+    my ($self, $basedir, $generated) = @_;
+
+    my $header =<<"HEADER";
+# Data about titles, sections, and URLs of manuals, used to expand references
+# in tag descriptions and add links for HTML output.  Each line of this file
+# has three fields separated by double colons:
+#
+#     <section> :: <title> :: <url>
+#
+# If <section> is an underscore, that line specifies the title and URL for the
+# whole manual.
+
+HEADER
+
+    my $data_path = "$basedir/" . $self->location;
+    my $parent_dir = path($data_path)->parent->stringify;
+    path($parent_dir)->mkpath
+      unless -e $parent_dir;
+
+    my $output = encode_utf8($header) . $generated;
+    path($data_path)->spew($output);
+
+    return;
+}
+
+=item extract_sections_from_links
+
+=cut
+
+sub extract_sections_from_links {
+    my ($self, $data_fd, $base_url, $page_name)= @_;
+
+    my $page_url = $base_url . $page_name;
+
+    my $mechanize = WWW::Mechanize->new();
+    $mechanize->get($page_url);
+
+    my $page_title = $mechanize->title;
+
+    # strip explanatory remark
+    $page_title =~ s{ \s* \N{EM DASH} .* $}{}x;
+
+    # underscore is a token for the whole page
+    write_line($data_fd, $VOLUME_KEY, $EMPTY, $page_title, $page_url);
+
+    my %by_section_key;
+    my $in_appendix = 0;
+
+    # https://stackoverflow.com/a/254687
+    for my $link ($mechanize->links) {
+
+        next
+          unless length $link->url;
+
+        # make lowercase
+        my $section_key = lc($link->url);
+
+        # strip hash; it's a fragment;
+        $section_key =~ s{^ [#] }{}x;
+
+        next
+          unless length $link->text;
+
+        next
+          if $link->text !~ qr{^ \s* ([.\d]+) \s+ (.+) $}x;
+
+        my $section_number = $1;
+        my $section_title = $2;
+
+        # drop final dot
+        $section_number =~ s{ [.]+ $}{}x;
+
+        # reduce consecutive whitespace
+        $section_title =~ s{ \s+ }{ }gx;
+
+        # includes hash
+        my $relative_destination = $link->url;
+
+        my $destination_base = $page_url;
+        $destination_base = dirname($page_url) . $SLASH
+          unless $destination_base =~ m{ / $}x
+          || $relative_destination =~ m{^ [#] }x;
+
+        my $full_destination = $destination_base . $relative_destination;
+
+        next
+          if exists $by_section_key{$section_key};
+
+        $by_section_key{$section_key}{title} = $section_title;
+        $by_section_key{$section_key}{number} = $section_number;
+        $by_section_key{$section_key}{destination} = $full_destination;
+
+        write_line($data_fd, $section_key, $section_number,
+            $section_title, $full_destination);
+    }
+
+    return;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    # single page version
+    # plain directory shows a file list
+    my $base_url = 'https://refspecs.linuxfoundation.org/FHS_3.0/';
+    my $index_name = 'fhs-3.0.html';
+
+    my $generated;
+    open(my $memory_fd, '>', \$generated)
+      or die encode_utf8('Cannot open scalar');
+
+    $self->extract_sections_from_links($memory_fd, $base_url, $index_name);
+
+    close $memory_fd;
+
+    $self->write_data_file($basedir, $generated);
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Authority/JavaPolicy.pm b/lib/Lintian/Data/Authority/JavaPolicy.pm
new file mode 100644
index 0000000..eaa6704
--- /dev/null
+++ b/lib/Lintian/Data/Authority/JavaPolicy.pm
@@ -0,0 +1,290 @@
+# -*- perl -*-
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2001 Colin Watson
+# Copyright (C) 2008 Jorda Polo
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Authority::JavaPolicy;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use List::SomeUtils qw(any first_value);
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+use WWW::Mechanize ();
+
+use Lintian::Output::Markdown qw(markdown_authority);
+
+const my $SLASH => q{/};
+const my $UNDERSCORE => q{_};
+
+const my $VOLUME_KEY => $UNDERSCORE;
+const my $SECTIONS => 'sections';
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::PreambledJSON';
+
+=head1 NAME
+
+Lintian::Data::Authority::JavaPolicy - Lintian interface for manual references
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Authority::JavaPolicy;
+
+=head1 DESCRIPTION
+
+Lintian::Data::Authority::JavaPolicy provides a way to load data files for
+manual references.
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item title
+
+=item shorthand
+
+=item location
+
+=item by_section_key
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Java Policy'
+);
+
+has shorthand => (
+    is => 'rw',
+    default => 'java-policy'
+);
+
+has location => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return 'authority/' . $self->shorthand . '.json';
+    }
+);
+
+has by_section_key => (is => 'rw', default => sub { {} });
+
+=item markdown_citation
+
+=cut
+
+sub markdown_citation {
+    my ($self, $section_key) = @_;
+
+    croak "Invalid section $section_key"
+      if $section_key eq $VOLUME_KEY;
+
+    my $volume_entry = $self->value($VOLUME_KEY);
+
+    # start with the citation to the overall manual.
+    my $volume_title = $volume_entry->{title};
+    my $volume_url   = $volume_entry->{destination};
+
+    my $section_title;
+    my $section_url;
+
+    if ($self->recognizes($section_key)) {
+
+        my $section_entry = $self->value($section_key);
+
+        $section_title = $section_entry->{title};
+        $section_url   = $section_entry->{destination};
+    }
+
+    return markdown_authority(
+        $volume_title, $volume_url,$section_key,
+        $section_title, $section_url
+    );
+}
+
+=item recognizes (KEY)
+
+Returns true if KEY is known, and false otherwise.
+
+=cut
+
+sub recognizes {
+    my ($self, $key) = @_;
+
+    return 0
+      unless length $key;
+
+    return 1
+      if exists $self->by_section_key->{$key};
+
+    return 0;
+}
+
+=item value (KEY)
+
+Returns the value attached to KEY if it was listed in the data
+file represented by this Lintian::Data instance and the undefined value
+otherwise.
+
+=cut
+
+sub value {
+    my ($self, $key) = @_;
+
+    return undef
+      unless length $key;
+
+    return $self->by_section_key->{$key};
+}
+
+=item load
+
+=cut
+
+sub load {
+    my ($self, $search_space, $our_vendor) = @_;
+
+    my @candidates = map { $_ . $SLASH . $self->location } @{$search_space};
+    my $path = first_value { -e } @candidates;
+
+    my $reference;
+
+    return 0
+      unless $self->read_file($path, \$reference);
+
+    my @sections = @{$reference // []};
+
+    for my $section (@sections) {
+
+        my $key = $section->{key};
+
+        # only store first value for duplicates
+        # silently ignore later values
+        $self->by_section_key->{$key} //= $section;
+    }
+
+    return 1;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    my $base_url = 'https://www.debian.org/doc/packaging-manuals/java-policy/';
+
+    my $mechanize = WWW::Mechanize->new();
+    $mechanize->get($base_url);
+
+    my $page_title = $mechanize->title;
+
+    my @sections;
+
+    # underscore is a token for the whole page
+    my %volume;
+    $volume{key} = $VOLUME_KEY;
+    $volume{title} = $page_title;
+    $volume{destination} = $base_url;
+
+    # store array to resemble web layout
+    # may contain duplicates
+    push(@sections, \%volume);
+
+    my $in_appendix = 0;
+
+    # https://stackoverflow.com/a/254687
+    for my $link ($mechanize->links) {
+
+        next
+          unless length $link->text;
+
+        next
+          if $link->text !~ qr{^ \s* ([.\d]+) \s+ (.+) $}x;
+
+        my $section_key = $1;
+        my $section_title = $2;
+
+        # drop final dots
+        $section_key =~ s{ [.]+ $}{}x;
+
+        # reduce consecutive whitespace
+        $section_title =~ s{ \s+ }{ }gx;
+
+        my $destination = $base_url . $link->url;
+
+        my @similar = grep { $_->{key} eq $section_key } @sections;
+        next
+          if (any { $_->{title} eq $section_title } @similar)
+          || (any { $_->{destination} eq $destination } @similar);
+
+        # Some manuals reuse section numbers for different references,
+        # e.g. the Debian Policy's normal and appendix sections are
+        # numbers that clash with each other. Track if we've already
+        # seen a section pointing to some other URL than the current one,
+        # and prepend it with an indicator
+        $in_appendix = 1
+          if any { $_->{destination} ne $destination } @similar;
+
+        $section_key = "appendix-$section_key"
+          if $in_appendix;
+
+        my %section;
+        $section{key} = $section_key;
+        $section{title} = $section_title;
+        $section{destination} = $destination;
+        push(@sections, \%section);
+    }
+
+    my $data_path = "$basedir/" . $self->location;
+    my $status = $self->write_file($SECTIONS, \@sections, $data_path);
+
+    return $status;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Authority/LintianManual.pm b/lib/Lintian/Data/Authority/LintianManual.pm
new file mode 100644
index 0000000..3fc7bd0
--- /dev/null
+++ b/lib/Lintian/Data/Authority/LintianManual.pm
@@ -0,0 +1,324 @@
+# -*- perl -*-
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2001 Colin Watson
+# Copyright (C) 2008 Jorda Polo
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Authority::LintianManual;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use IPC::Run3;
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+use URI::file;
+use WWW::Mechanize ();
+
+use Lintian::Output::Markdown qw(markdown_authority);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $COLON => q{:};
+const my $UNDERSCORE => q{_};
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+const my $TWO_PARTS => 2;
+
+const my $VOLUME_KEY => $UNDERSCORE;
+const my $SEPARATOR => $COLON x 2;
+
+const my $WAIT_STATUS_SHIFT => 8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::JoinedLines';
+
+=head1 NAME
+
+Lintian::Data::Authority::LintianManual - Lintian interface for manual references
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Authority::LintianManual;
+
+=head1 DESCRIPTION
+
+Lintian::Data::Authority::LintianManual provides a way to load data files for
+manual references.
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item title
+
+=item shorthand
+
+=item location
+
+=item separator
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Lintian Manual'
+);
+
+has shorthand => (
+    is => 'rw',
+    default => 'lintian-manual'
+);
+
+has location => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return 'authority/' . $self->shorthand;
+    }
+);
+
+has separator => (
+    is => 'rw',
+    default => sub { qr/::/ }
+);
+
+=item consumer
+
+=cut
+
+sub consumer {
+    my ($self, $key, $remainder, $previous) = @_;
+
+    return undef
+      if defined $previous;
+
+    my ($title, $url)= split($self->separator, $remainder, $TWO_PARTS);
+
+    my %entry;
+    $entry{title} = $title;
+    $entry{url} = $url;
+
+    return \%entry;
+}
+
+=item markdown_citation
+
+=cut
+
+sub markdown_citation {
+    my ($self, $section_key) = @_;
+
+    croak "Invalid section $section_key"
+      if $section_key eq $VOLUME_KEY;
+
+    my $volume_entry = $self->value($VOLUME_KEY);
+
+    # start with the citation to the overall manual.
+    my $volume_title = $volume_entry->{title};
+    my $volume_url   = $volume_entry->{url};
+
+    my $section_title;
+    my $section_url;
+
+    if ($self->recognizes($section_key)) {
+
+        my $section_entry = $self->value($section_key);
+
+        $section_title = $section_entry->{title};
+        $section_url   = $section_entry->{url};
+    }
+
+    return markdown_authority(
+        $volume_title, $volume_url,$section_key,
+        $section_title, $section_url
+    );
+}
+
+=item write_line
+
+=cut
+
+sub write_line {
+    my ($data_fd, $section_key, $section_title, $destination) = @_;
+
+    # drop final dots
+    $section_key =~ s{ [.]+ $}{}x;
+
+    # reduce consecutive whitespace
+    $section_title =~ s{ \s+ }{ }gx;
+
+    my $line= join($SEPARATOR,$section_key, $section_title, $destination);
+
+    say {$data_fd} encode_utf8($line);
+
+    return;
+}
+
+=item write_data_file
+
+=cut
+
+sub write_data_file {
+    my ($self, $basedir, $generated) = @_;
+
+    my $header =<<"HEADER";
+# Data about titles, sections, and URLs of manuals, used to expand references
+# in tag descriptions and add links for HTML output.  Each line of this file
+# has three fields separated by double colons:
+#
+#     <section> :: <title> :: <url>
+#
+# If <section> is an underscore, that line specifies the title and URL for the
+# whole manual.
+
+HEADER
+
+    my $data_path = "$basedir/" . $self->location;
+    my $parent_dir = path($data_path)->parent->stringify;
+    path($parent_dir)->mkpath
+      unless -e $parent_dir;
+
+    my $output = encode_utf8($header) . $generated;
+    path($data_path)->spew($output);
+
+    return;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    # WWW::Mechanize will not parse page title without the suffix
+    my $temp_tiny = Path::Tiny->tempfile(
+        TEMPLATE => 'lintian-manual-XXXXXXXX',
+        SUFFIX => '.html'
+    );
+    my $local_uri = URI::file->new_abs($temp_tiny->stringify);
+
+    # for rst2html
+    local $ENV{LC_ALL} = 'en_US.UTF-8';
+
+    my $stderr;
+    run3(['rst2html', "$ENV{LINTIAN_BASE}/doc/lintian.rst"],
+        undef, $local_uri->file, \$stderr);
+    my $status = ($? >> $WAIT_STATUS_SHIFT);
+
+    # stderr already in UTF-8
+    die $stderr
+      if $status;
+
+    my $generated;
+    open(my $memory_fd, '>', \$generated)
+      or die encode_utf8("Cannot open scalar: $!");
+
+    my $page_url = 'https://lintian.debian.org/manual/index.html';
+
+    my $mechanize = WWW::Mechanize->new();
+    $mechanize->get($local_uri);
+
+    my $page_title = $mechanize->title;
+
+    # underscore is a token for the whole page
+    write_line($memory_fd, $VOLUME_KEY, $page_title, $page_url);
+
+    my %by_section_key;
+    my $in_appendix = 0;
+
+    # https://stackoverflow.com/a/254687
+    for my $link ($mechanize->links) {
+
+        next
+          unless length $link->text;
+
+        next
+          if $link->text !~ qr{^ \s* ([.\d]+) \s+ (.+) $}x;
+
+        my $section_key = $1;
+        my $section_title = $2;
+
+        # drop final dots
+        $section_key =~ s{ [.]+ $}{}x;
+
+        # reduce consecutive whitespace
+        $section_title =~ s{ \s+ }{ }gx;
+
+        my $destination = $page_url . $link->url;
+
+        next
+          if exists $by_section_key{$section_key}
+          && ( $by_section_key{$section_key}{title} eq $section_title
+            || $by_section_key{$section_key}{destination} eq $destination);
+
+        # Some manuals reuse section numbers for different references,
+        # e.g. the Debian Policy's normal and appendix sections are
+        # numbers that clash with each other. Track if we've already
+        # seen a section pointing to some other URL than the current one,
+        # and prepend it with an indicator
+        $in_appendix = 1
+          if exists $by_section_key{$section_key}
+          && $by_section_key{$section_key}{destination} ne $destination;
+
+        $section_key = "appendix-$section_key"
+          if $in_appendix;
+
+        $by_section_key{$section_key}{title} = $section_title;
+        $by_section_key{$section_key}{destination} = $destination;
+
+        write_line($memory_fd, $section_key, $section_title, $destination);
+    }
+
+    close $memory_fd;
+
+    $self->write_data_file($basedir, $generated);
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Authority/MenuManual.pm b/lib/Lintian/Data/Authority/MenuManual.pm
new file mode 100644
index 0000000..c8a2878
--- /dev/null
+++ b/lib/Lintian/Data/Authority/MenuManual.pm
@@ -0,0 +1,316 @@
+# -*- perl -*-
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2001 Colin Watson
+# Copyright (C) 2008 Jorda Polo
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Authority::MenuManual;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+use WWW::Mechanize ();
+
+use Lintian::Output::Markdown qw(markdown_authority);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $COLON => q{:};
+const my $UNDERSCORE => q{_};
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+const my $TWO_PARTS => 2;
+
+const my $VOLUME_KEY => $UNDERSCORE;
+const my $SEPARATOR => $COLON x 2;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::JoinedLines';
+
+=head1 NAME
+
+Lintian::Data::Authority::MenuManual - Lintian interface for manual references
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Authority::MenuManual;
+
+=head1 DESCRIPTION
+
+Lintian::Data::Authority::MenuManual provides a way to load data files for
+manual references.
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item title
+
+=item shorthand
+
+=item location
+
+=item separator
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Menu Manual'
+);
+
+has shorthand => (
+    is => 'rw',
+    default => 'menu-manual'
+);
+
+has location => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return 'authority/' . $self->shorthand;
+    }
+);
+
+has separator => (
+    is => 'rw',
+    default => sub { qr/::/ }
+);
+
+=item consumer
+
+=cut
+
+sub consumer {
+    my ($self, $key, $remainder, $previous) = @_;
+
+    return undef
+      if defined $previous;
+
+    my ($title, $url)= split($self->separator, $remainder, $TWO_PARTS);
+
+    my %entry;
+    $entry{title} = $title;
+    $entry{url} = $url;
+
+    return \%entry;
+}
+
+=item markdown_citation
+
+=cut
+
+sub markdown_citation {
+    my ($self, $section_key) = @_;
+
+    croak "Invalid section $section_key"
+      if $section_key eq $VOLUME_KEY;
+
+    my $volume_entry = $self->value($VOLUME_KEY);
+
+    # start with the citation to the overall manual.
+    my $volume_title = $volume_entry->{title};
+    my $volume_url   = $volume_entry->{url};
+
+    my $section_title;
+    my $section_url;
+
+    if ($self->recognizes($section_key)) {
+
+        my $section_entry = $self->value($section_key);
+
+        $section_title = $section_entry->{title};
+        $section_url   = $section_entry->{url};
+    }
+
+    return markdown_authority(
+        $volume_title, $volume_url,$section_key,
+        $section_title, $section_url
+    );
+}
+
+=item write_line
+
+=cut
+
+sub write_line {
+    my ($data_fd, $section_key, $section_title, $destination) = @_;
+
+    # drop final dots
+    $section_key =~ s{ [.]+ $}{}x;
+
+    # reduce consecutive whitespace
+    $section_title =~ s{ \s+ }{ }gx;
+
+    my $line= join($SEPARATOR,$section_key, $section_title, $destination);
+
+    say {$data_fd} encode_utf8($line);
+
+    return;
+}
+
+=item write_data_file
+
+=cut
+
+sub write_data_file {
+    my ($self, $basedir, $generated) = @_;
+
+    my $header =<<"HEADER";
+# Data about titles, sections, and URLs of manuals, used to expand references
+# in tag descriptions and add links for HTML output.  Each line of this file
+# has three fields separated by double colons:
+#
+#     <section> :: <title> :: <url>
+#
+# If <section> is an underscore, that line specifies the title and URL for the
+# whole manual.
+
+HEADER
+
+    my $data_path = "$basedir/" . $self->location;
+    my $parent_dir = path($data_path)->parent->stringify;
+    path($parent_dir)->mkpath
+      unless -e $parent_dir;
+
+    my $output = encode_utf8($header) . $generated;
+    path($data_path)->spew($output);
+
+    return;
+}
+
+=item extract_sections_from_links
+
+=cut
+
+sub extract_sections_from_links {
+    my ($self, $data_fd, $base_url)= @_;
+
+    my $mechanize = WWW::Mechanize->new();
+    $mechanize->get($base_url);
+
+    my $page_title = $mechanize->title;
+
+    # strip explanatory remark
+    $page_title =~ s{ \s* \N{EM DASH} .* $}{}x;
+
+    # underscore is a token for the whole page
+    write_line($data_fd, $VOLUME_KEY, $page_title, $base_url);
+
+    my %by_section_key;
+    my $in_appendix = 0;
+
+    # https://stackoverflow.com/a/254687
+    for my $link ($mechanize->links) {
+
+        next
+          unless length $link->text;
+
+        next
+          if $link->text !~ qr{^ \s* ([.\d]+) \s+ (.+) $}x;
+
+        my $section_key = $1;
+        my $section_title = $2;
+
+        # drop final dots
+        $section_key =~ s{ [.]+ $}{}x;
+
+        # reduce consecutive whitespace
+        $section_title =~ s{ \s+ }{ }gx;
+
+        my $destination = $base_url . $link->url;
+
+        next
+          if exists $by_section_key{$section_key}
+          && ( $by_section_key{$section_key}{title} eq $section_title
+            || $by_section_key{$section_key}{destination} eq $destination);
+
+        # Some manuals reuse section numbers for different references,
+        # e.g. the Debian Policy's normal and appendix sections are
+        # numbers that clash with each other. Track if we've already
+        # seen a section pointing to some other URL than the current one,
+        # and prepend it with an indicator
+        $in_appendix = 1
+          if exists $by_section_key{$section_key}
+          && $by_section_key{$section_key}{destination} ne $destination;
+
+        $section_key = "appendix-$section_key"
+          if $in_appendix;
+
+        $by_section_key{$section_key}{title} = $section_title;
+        $by_section_key{$section_key}{destination} = $destination;
+
+        write_line($data_fd, $section_key, $section_title, $destination);
+    }
+
+    return;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    my $base_url = 'https://www.debian.org/doc/packaging-manuals/menu.html/';
+
+    my $generated;
+    open(my $memory_fd, '>', \$generated)
+      or die encode_utf8('Cannot open scalar');
+
+    $self->extract_sections_from_links($memory_fd, $base_url);
+
+    close $memory_fd;
+
+    $self->write_data_file($basedir, $generated);
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Authority/MenuPolicy.pm b/lib/Lintian/Data/Authority/MenuPolicy.pm
new file mode 100644
index 0000000..e0f710a
--- /dev/null
+++ b/lib/Lintian/Data/Authority/MenuPolicy.pm
@@ -0,0 +1,316 @@
+# -*- perl -*-
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2001 Colin Watson
+# Copyright (C) 2008 Jorda Polo
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Authority::MenuPolicy;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+use WWW::Mechanize ();
+
+use Lintian::Output::Markdown qw(markdown_authority);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $COLON => q{:};
+const my $UNDERSCORE => q{_};
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+const my $TWO_PARTS => 2;
+
+const my $VOLUME_KEY => $UNDERSCORE;
+const my $SEPARATOR => $COLON x 2;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::JoinedLines';
+
+=head1 NAME
+
+Lintian::Data::Authority::MenuPolicy - Lintian interface for manual references
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Authority::MenuPolicy;
+
+=head1 DESCRIPTION
+
+Lintian::Data::Authority::MenuPolicy provides a way to load data files for
+manual references.
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item title
+
+=item shorthand
+
+=item location
+
+=item separator
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Menu Policy'
+);
+
+has shorthand => (
+    is => 'rw',
+    default => 'menu-policy'
+);
+
+has location => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return 'authority/' . $self->shorthand;
+    }
+);
+
+has separator => (
+    is => 'rw',
+    default => sub { qr/::/ }
+);
+
+=item consumer
+
+=cut
+
+sub consumer {
+    my ($self, $key, $remainder, $previous) = @_;
+
+    return undef
+      if defined $previous;
+
+    my ($title, $url)= split($self->separator, $remainder, $TWO_PARTS);
+
+    my %entry;
+    $entry{title} = $title;
+    $entry{url} = $url;
+
+    return \%entry;
+}
+
+=item markdown_citation
+
+=cut
+
+sub markdown_citation {
+    my ($self, $section_key) = @_;
+
+    croak "Invalid section $section_key"
+      if $section_key eq $VOLUME_KEY;
+
+    my $volume_entry = $self->value($VOLUME_KEY);
+
+    # start with the citation to the overall manual.
+    my $volume_title = $volume_entry->{title};
+    my $volume_url   = $volume_entry->{url};
+
+    my $section_title;
+    my $section_url;
+
+    if ($self->recognizes($section_key)) {
+
+        my $section_entry = $self->value($section_key);
+
+        $section_title = $section_entry->{title};
+        $section_url   = $section_entry->{url};
+    }
+
+    return markdown_authority(
+        $volume_title, $volume_url,$section_key,
+        $section_title, $section_url
+    );
+}
+
+=item write_line
+
+=cut
+
+sub write_line {
+    my ($data_fd, $section_key, $section_title, $destination) = @_;
+
+    # drop final dots
+    $section_key =~ s{ [.]+ $}{}x;
+
+    # reduce consecutive whitespace
+    $section_title =~ s{ \s+ }{ }gx;
+
+    my $line= join($SEPARATOR,$section_key, $section_title, $destination);
+
+    say {$data_fd} encode_utf8($line);
+
+    return;
+}
+
+=item write_data_file
+
+=cut
+
+sub write_data_file {
+    my ($self, $basedir, $generated) = @_;
+
+    my $header =<<"HEADER";
+# Data about titles, sections, and URLs of manuals, used to expand references
+# in tag descriptions and add links for HTML output.  Each line of this file
+# has three fields separated by double colons:
+#
+#     <section> :: <title> :: <url>
+#
+# If <section> is an underscore, that line specifies the title and URL for the
+# whole manual.
+
+HEADER
+
+    my $data_path = "$basedir/" . $self->location;
+    my $parent_dir = path($data_path)->parent->stringify;
+    path($parent_dir)->mkpath
+      unless -e $parent_dir;
+
+    my $output = encode_utf8($header) . $generated;
+    path($data_path)->spew($output);
+
+    return;
+}
+
+=item extract_sections_from_links
+
+=cut
+
+sub extract_sections_from_links {
+    my ($self, $data_fd, $base_url)= @_;
+
+    my $mechanize = WWW::Mechanize->new();
+    $mechanize->get($base_url);
+
+    my $page_title = $mechanize->title;
+
+    # strip explanatory remark
+    $page_title =~ s{ \s* \N{EM DASH} .* $}{}x;
+
+    # underscore is a token for the whole page
+    write_line($data_fd, $VOLUME_KEY, $page_title, $base_url);
+
+    my %by_section_key;
+    my $in_appendix = 0;
+
+    # https://stackoverflow.com/a/254687
+    for my $link ($mechanize->links) {
+
+        next
+          unless length $link->text;
+
+        next
+          if $link->text !~ qr{^ \s* ([.\d]+) \s+ (.+) $}x;
+
+        my $section_key = $1;
+        my $section_title = $2;
+
+        # drop final dots
+        $section_key =~ s{ [.]+ $}{}x;
+
+        # reduce consecutive whitespace
+        $section_title =~ s{ \s+ }{ }gx;
+
+        my $destination = $base_url . $link->url;
+
+        next
+          if exists $by_section_key{$section_key}
+          && ( $by_section_key{$section_key}{title} eq $section_title
+            || $by_section_key{$section_key}{destination} eq $destination);
+
+        # Some manuals reuse section numbers for different references,
+        # e.g. the Debian Policy's normal and appendix sections are
+        # numbers that clash with each other. Track if we've already
+        # seen a section pointing to some other URL than the current one,
+        # and prepend it with an indicator
+        $in_appendix = 1
+          if exists $by_section_key{$section_key}
+          && $by_section_key{$section_key}{destination} ne $destination;
+
+        $section_key = "appendix-$section_key"
+          if $in_appendix;
+
+        $by_section_key{$section_key}{title} = $section_title;
+        $by_section_key{$section_key}{destination} = $destination;
+
+        write_line($data_fd, $section_key, $section_title, $destination);
+    }
+
+    return;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    my $base_url = 'https://www.debian.org/doc/packaging-manuals/menu-policy/';
+
+    my $generated;
+    open(my $memory_fd, '>', \$generated)
+      or die encode_utf8('Cannot open scalar');
+
+    $self->extract_sections_from_links($memory_fd, $base_url);
+
+    close $memory_fd;
+
+    $self->write_data_file($basedir, $generated);
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Authority/NewMaintainer.pm b/lib/Lintian/Data/Authority/NewMaintainer.pm
new file mode 100644
index 0000000..bd8c933
--- /dev/null
+++ b/lib/Lintian/Data/Authority/NewMaintainer.pm
@@ -0,0 +1,290 @@
+# -*- perl -*-
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2001 Colin Watson
+# Copyright (C) 2008 Jorda Polo
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Authority::NewMaintainer;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use List::SomeUtils qw(any first_value);
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+use WWW::Mechanize ();
+
+use Lintian::Output::Markdown qw(markdown_authority);
+
+const my $SLASH => q{/};
+const my $UNDERSCORE => q{_};
+
+const my $VOLUME_KEY => $UNDERSCORE;
+const my $SECTIONS => 'sections';
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::PreambledJSON';
+
+=head1 NAME
+
+Lintian::Data::Authority::NewMaintainer - Lintian interface for manual references
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Authority::NewMaintainer;
+
+=head1 DESCRIPTION
+
+Lintian::Data::Authority::NewMaintainer provides a way to load data files for
+manual references.
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item title
+
+=item shorthand
+
+=item location
+
+=item by_section_key
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'New Maintainer\'s Guide'
+);
+
+has shorthand => (
+    is => 'rw',
+    default => 'new-maintainer'
+);
+
+has location => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return 'authority/' . $self->shorthand . '.json';
+    }
+);
+
+has by_section_key => (is => 'rw', default => sub { {} });
+
+=item markdown_citation
+
+=cut
+
+sub markdown_citation {
+    my ($self, $section_key) = @_;
+
+    croak "Invalid section $section_key"
+      if $section_key eq $VOLUME_KEY;
+
+    my $volume_entry = $self->value($VOLUME_KEY);
+
+    # start with the citation to the overall manual.
+    my $volume_title = $volume_entry->{title};
+    my $volume_url   = $volume_entry->{destination};
+
+    my $section_title;
+    my $section_url;
+
+    if ($self->recognizes($section_key)) {
+
+        my $section_entry = $self->value($section_key);
+
+        $section_title = $section_entry->{title};
+        $section_url   = $section_entry->{destination};
+    }
+
+    return markdown_authority(
+        $volume_title, $volume_url,$section_key,
+        $section_title, $section_url
+    );
+}
+
+=item recognizes (KEY)
+
+Returns true if KEY is known, and false otherwise.
+
+=cut
+
+sub recognizes {
+    my ($self, $key) = @_;
+
+    return 0
+      unless length $key;
+
+    return 1
+      if exists $self->by_section_key->{$key};
+
+    return 0;
+}
+
+=item value (KEY)
+
+Returns the value attached to KEY if it was listed in the data
+file represented by this Lintian::Data instance and the undefined value
+otherwise.
+
+=cut
+
+sub value {
+    my ($self, $key) = @_;
+
+    return undef
+      unless length $key;
+
+    return $self->by_section_key->{$key};
+}
+
+=item load
+
+=cut
+
+sub load {
+    my ($self, $search_space, $our_vendor) = @_;
+
+    my @candidates = map { $_ . $SLASH . $self->location } @{$search_space};
+    my $path = first_value { -e } @candidates;
+
+    my $reference;
+
+    return 0
+      unless $self->read_file($path, \$reference);
+
+    my @sections = @{$reference // []};
+
+    for my $section (@sections) {
+
+        my $key = $section->{key};
+
+        # only store first value for duplicates
+        # silently ignore later values
+        $self->by_section_key->{$key} //= $section;
+    }
+
+    return 1;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    my $base_url = 'https://www.debian.org/doc/manuals/maint-guide/index.html';
+
+    my $mechanize = WWW::Mechanize->new();
+    $mechanize->get($base_url);
+
+    my $page_title = $mechanize->title;
+
+    my @sections;
+
+    # underscore is a token for the whole page
+    my %volume;
+    $volume{key} = $VOLUME_KEY;
+    $volume{title} = $page_title;
+    $volume{destination} = $base_url;
+
+    # store array to resemble web layout
+    # may contain duplicates
+    push(@sections, \%volume);
+
+    my $in_appendix = 0;
+
+    # https://stackoverflow.com/a/254687
+    for my $link ($mechanize->links) {
+
+        next
+          unless length $link->text;
+
+        next
+          if $link->text !~ qr{^ \s* ([.\d[:upper:]]+) \s+ (.+) $}x;
+
+        my $section_key = $1;
+        my $section_title = $2;
+
+        # drop final dots
+        $section_key =~ s{ [.]+ $}{}x;
+
+        # reduce consecutive whitespace
+        $section_title =~ s{ \s+ }{ }gx;
+
+        my $destination = $base_url . $link->url;
+
+        my @similar = grep { $_->{key} eq $section_key } @sections;
+        next
+          if (any { $_->{title} eq $section_title } @similar)
+          || (any { $_->{destination} eq $destination } @similar);
+
+        # Some manuals reuse section numbers for different references,
+        # e.g. the Debian Policy's normal and appendix sections are
+        # numbers that clash with each other. Track if we've already
+        # seen a section pointing to some other URL than the current one,
+        # and prepend it with an indicator
+        $in_appendix = 1
+          if any { $_->{destination} ne $destination } @similar;
+
+        $section_key = "appendix-$section_key"
+          if $in_appendix;
+
+        my %section;
+        $section{key} = $section_key;
+        $section{title} = $section_title;
+        $section{destination} = $destination;
+        push(@sections, \%section);
+    }
+
+    my $data_path = "$basedir/" . $self->location;
+    my $status = $self->write_file($SECTIONS, \@sections, $data_path);
+
+    return $status;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Authority/PerlPolicy.pm b/lib/Lintian/Data/Authority/PerlPolicy.pm
new file mode 100644
index 0000000..92dc31a
--- /dev/null
+++ b/lib/Lintian/Data/Authority/PerlPolicy.pm
@@ -0,0 +1,316 @@
+# -*- perl -*-
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2001 Colin Watson
+# Copyright (C) 2008 Jorda Polo
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Authority::PerlPolicy;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+use WWW::Mechanize ();
+
+use Lintian::Output::Markdown qw(markdown_authority);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $COLON => q{:};
+const my $UNDERSCORE => q{_};
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+const my $TWO_PARTS => 2;
+
+const my $VOLUME_KEY => $UNDERSCORE;
+const my $SEPARATOR => $COLON x 2;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::JoinedLines';
+
+=head1 NAME
+
+Lintian::Data::Authority::PerlPolicy - Lintian interface for manual references
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Authority::PerlPolicy;
+
+=head1 DESCRIPTION
+
+Lintian::Data::Authority::PerlPolicy provides a way to load data files for
+manual references.
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item title
+
+=item shorthand
+
+=item location
+
+=item separator
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Perl Policy'
+);
+
+has shorthand => (
+    is => 'rw',
+    default => 'perl-policy'
+);
+
+has location => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return 'authority/' . $self->shorthand;
+    }
+);
+
+has separator => (
+    is => 'rw',
+    default => sub { qr/::/ }
+);
+
+=item consumer
+
+=cut
+
+sub consumer {
+    my ($self, $key, $remainder, $previous) = @_;
+
+    return undef
+      if defined $previous;
+
+    my ($title, $url)= split($self->separator, $remainder, $TWO_PARTS);
+
+    my %entry;
+    $entry{title} = $title;
+    $entry{url} = $url;
+
+    return \%entry;
+}
+
+=item markdown_citation
+
+=cut
+
+sub markdown_citation {
+    my ($self, $section_key) = @_;
+
+    croak "Invalid section $section_key"
+      if $section_key eq $VOLUME_KEY;
+
+    my $volume_entry = $self->value($VOLUME_KEY);
+
+    # start with the citation to the overall manual.
+    my $volume_title = $volume_entry->{title};
+    my $volume_url   = $volume_entry->{url};
+
+    my $section_title;
+    my $section_url;
+
+    if ($self->recognizes($section_key)) {
+
+        my $section_entry = $self->value($section_key);
+
+        $section_title = $section_entry->{title};
+        $section_url   = $section_entry->{url};
+    }
+
+    return markdown_authority(
+        $volume_title, $volume_url,$section_key,
+        $section_title, $section_url
+    );
+}
+
+=item write_line
+
+=cut
+
+sub write_line {
+    my ($data_fd, $section_key, $section_title, $destination) = @_;
+
+    # drop final dots
+    $section_key =~ s{ [.]+ $}{}x;
+
+    # reduce consecutive whitespace
+    $section_title =~ s{ \s+ }{ }gx;
+
+    my $line= join($SEPARATOR,$section_key, $section_title, $destination);
+
+    say {$data_fd} encode_utf8($line);
+
+    return;
+}
+
+=item write_data_file
+
+=cut
+
+sub write_data_file {
+    my ($self, $basedir, $generated) = @_;
+
+    my $header =<<"HEADER";
+# Data about titles, sections, and URLs of manuals, used to expand references
+# in tag descriptions and add links for HTML output.  Each line of this file
+# has three fields separated by double colons:
+#
+#     <section> :: <title> :: <url>
+#
+# If <section> is an underscore, that line specifies the title and URL for the
+# whole manual.
+
+HEADER
+
+    my $data_path = "$basedir/" . $self->location;
+    my $parent_dir = path($data_path)->parent->stringify;
+    path($parent_dir)->mkpath
+      unless -e $parent_dir;
+
+    my $output = encode_utf8($header) . $generated;
+    path($data_path)->spew($output);
+
+    return;
+}
+
+=item extract_sections_from_links
+
+=cut
+
+sub extract_sections_from_links {
+    my ($self, $data_fd, $base_url)= @_;
+
+    my $mechanize = WWW::Mechanize->new();
+    $mechanize->get($base_url);
+
+    my $page_title = $mechanize->title;
+
+    # strip explanatory remark
+    $page_title =~ s{ \s* \N{EM DASH} .* $}{}x;
+
+    # underscore is a token for the whole page
+    write_line($data_fd, $VOLUME_KEY, $page_title, $base_url);
+
+    my %by_section_key;
+    my $in_appendix = 0;
+
+    # https://stackoverflow.com/a/254687
+    for my $link ($mechanize->links) {
+
+        next
+          unless length $link->text;
+
+        next
+          if $link->text !~ qr{^ \s* ([A-Z]|[A-Z]?[.\d]+) \s+ (.+) $}x;
+
+        my $section_key = $1;
+        my $section_title = $2;
+
+        # drop final dots
+        $section_key =~ s{ [.]+ $}{}x;
+
+        # reduce consecutive whitespace
+        $section_title =~ s{ \s+ }{ }gx;
+
+        my $destination = $base_url . $link->url;
+
+        next
+          if exists $by_section_key{$section_key}
+          && ( $by_section_key{$section_key}{title} eq $section_title
+            || $by_section_key{$section_key}{destination} eq $destination);
+
+        # Some manuals reuse section numbers for different references,
+        # e.g. the Debian Policy's normal and appendix sections are
+        # numbers that clash with each other. Track if we've already
+        # seen a section pointing to some other URL than the current one,
+        # and prepend it with an indicator
+        $in_appendix = 1
+          if exists $by_section_key{$section_key}
+          && $by_section_key{$section_key}{destination} ne $destination;
+
+        $section_key = "appendix-$section_key"
+          if $in_appendix;
+
+        $by_section_key{$section_key}{title} = $section_title;
+        $by_section_key{$section_key}{destination} = $destination;
+
+        write_line($data_fd, $section_key, $section_title, $destination);
+    }
+
+    return;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    my $base_url = 'https://www.debian.org/doc/packaging-manuals/perl-policy/';
+
+    my $generated;
+    open(my $memory_fd, '>', \$generated)
+      or die encode_utf8('Cannot open scalar');
+
+    $self->extract_sections_from_links($memory_fd, $base_url);
+
+    close $memory_fd;
+
+    $self->write_data_file($basedir, $generated);
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Authority/PythonPolicy.pm b/lib/Lintian/Data/Authority/PythonPolicy.pm
new file mode 100644
index 0000000..ebeda04
--- /dev/null
+++ b/lib/Lintian/Data/Authority/PythonPolicy.pm
@@ -0,0 +1,317 @@
+# -*- perl -*-
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2001 Colin Watson
+# Copyright (C) 2008 Jorda Polo
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Authority::PythonPolicy;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+use WWW::Mechanize ();
+
+use Lintian::Output::Markdown qw(markdown_authority);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $COLON => q{:};
+const my $UNDERSCORE => q{_};
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+const my $TWO_PARTS => 2;
+
+const my $VOLUME_KEY => $UNDERSCORE;
+const my $SEPARATOR => $COLON x 2;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::JoinedLines';
+
+=head1 NAME
+
+Lintian::Data::Authority::PythonPolicy - Lintian interface for manual references
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Authority::PythonPolicy;
+
+=head1 DESCRIPTION
+
+Lintian::Data::Authority::PythonPolicy provides a way to load data files for
+manual references.
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item title
+
+=item shorthand
+
+=item location
+
+=item separator
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Python Policy'
+);
+
+has shorthand => (
+    is => 'rw',
+    default => 'python-policy'
+);
+
+has location => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return 'authority/' . $self->shorthand;
+    }
+);
+
+has separator => (
+    is => 'rw',
+    default => sub { qr/::/ }
+);
+
+=item consumer
+
+=cut
+
+sub consumer {
+    my ($self, $key, $remainder, $previous) = @_;
+
+    return undef
+      if defined $previous;
+
+    my ($title, $url)= split($self->separator, $remainder, $TWO_PARTS);
+
+    my %entry;
+    $entry{title} = $title;
+    $entry{url} = $url;
+
+    return \%entry;
+}
+
+=item markdown_citation
+
+=cut
+
+sub markdown_citation {
+    my ($self, $section_key) = @_;
+
+    croak "Invalid section $section_key"
+      if $section_key eq $VOLUME_KEY;
+
+    my $volume_entry = $self->value($VOLUME_KEY);
+
+    # start with the citation to the overall manual.
+    my $volume_title = $volume_entry->{title};
+    my $volume_url   = $volume_entry->{url};
+
+    my $section_title;
+    my $section_url;
+
+    if ($self->recognizes($section_key)) {
+
+        my $section_entry = $self->value($section_key);
+
+        $section_title = $section_entry->{title};
+        $section_url   = $section_entry->{url};
+    }
+
+    return markdown_authority(
+        $volume_title, $volume_url,$section_key,
+        $section_title, $section_url
+    );
+}
+
+=item write_line
+
+=cut
+
+sub write_line {
+    my ($data_fd, $section_key, $section_title, $destination) = @_;
+
+    # drop final dots
+    $section_key =~ s{ [.]+ $}{}x;
+
+    # reduce consecutive whitespace
+    $section_title =~ s{ \s+ }{ }gx;
+
+    my $line= join($SEPARATOR,$section_key, $section_title, $destination);
+
+    say {$data_fd} encode_utf8($line);
+
+    return;
+}
+
+=item write_data_file
+
+=cut
+
+sub write_data_file {
+    my ($self, $basedir, $generated) = @_;
+
+    my $header =<<"HEADER";
+# Data about titles, sections, and URLs of manuals, used to expand references
+# in tag descriptions and add links for HTML output.  Each line of this file
+# has three fields separated by double colons:
+#
+#     <section> :: <title> :: <url>
+#
+# If <section> is an underscore, that line specifies the title and URL for the
+# whole manual.
+
+HEADER
+
+    my $data_path = "$basedir/" . $self->location;
+    my $parent_dir = path($data_path)->parent->stringify;
+    path($parent_dir)->mkpath
+      unless -e $parent_dir;
+
+    my $output = encode_utf8($header) . $generated;
+    path($data_path)->spew($output);
+
+    return;
+}
+
+=item extract_sections_from_links
+
+=cut
+
+sub extract_sections_from_links {
+    my ($self, $data_fd, $base_url)= @_;
+
+    my $mechanize = WWW::Mechanize->new();
+    $mechanize->get($base_url);
+
+    my $page_title = $mechanize->title;
+
+    # strip explanatory remark
+    $page_title =~ s{ \s* \N{EM DASH} .* $}{}x;
+
+    # underscore is a token for the whole page
+    write_line($data_fd, $VOLUME_KEY, $page_title, $base_url);
+
+    my %by_section_key;
+    my $in_appendix = 0;
+
+    # https://stackoverflow.com/a/254687
+    for my $link ($mechanize->links) {
+
+        next
+          unless length $link->text;
+
+        next
+          if $link->text !~ qr{^ \s* ([.\d]+) \s+ (.+) $}x;
+
+        my $section_key = $1;
+        my $section_title = $2;
+
+        # drop final dots
+        $section_key =~ s{ [.]+ $}{}x;
+
+        # reduce consecutive whitespace
+        $section_title =~ s{ \s+ }{ }gx;
+
+        my $destination = $base_url . $link->url;
+
+        next
+          if exists $by_section_key{$section_key}
+          && ( $by_section_key{$section_key}{title} eq $section_title
+            || $by_section_key{$section_key}{destination} eq $destination);
+
+        # Some manuals reuse section numbers for different references,
+        # e.g. the Debian Policy's normal and appendix sections are
+        # numbers that clash with each other. Track if we've already
+        # seen a section pointing to some other URL than the current one,
+        # and prepend it with an indicator
+        $in_appendix = 1
+          if exists $by_section_key{$section_key}
+          && $by_section_key{$section_key}{destination} ne $destination;
+
+        $section_key = "appendix-$section_key"
+          if $in_appendix;
+
+        $by_section_key{$section_key}{title} = $section_title;
+        $by_section_key{$section_key}{destination} = $destination;
+
+        write_line($data_fd, $section_key, $section_title, $destination);
+    }
+
+    return;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    my $base_url
+      = 'https://www.debian.org/doc/packaging-manuals/python-policy/';
+
+    my $generated;
+    open(my $memory_fd, '>', \$generated)
+      or die encode_utf8('Cannot open scalar');
+
+    $self->extract_sections_from_links($memory_fd, $base_url);
+
+    close $memory_fd;
+
+    $self->write_data_file($basedir, $generated);
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Authority/VimPolicy.pm b/lib/Lintian/Data/Authority/VimPolicy.pm
new file mode 100644
index 0000000..6ffbe91
--- /dev/null
+++ b/lib/Lintian/Data/Authority/VimPolicy.pm
@@ -0,0 +1,459 @@
+# -*- perl -*-
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2001 Colin Watson
+# Copyright (C) 2008 Jorda Polo
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2017-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Authority::VimPolicy;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use File::Basename qw(basename);
+use IPC::Run3;
+use HTML::TokeParser::Simple;
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Output::Markdown qw(markdown_authority);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $COLON => q{:};
+const my $INDENT => $SPACE x 4;
+const my $UNDERSCORE => q{_};
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+const my $TWO_PARTS => 2;
+
+const my $VOLUME_KEY => $UNDERSCORE;
+const my $SEPARATOR => $COLON x 2;
+
+const my $WAIT_STATUS_SHIFT => 8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::JoinedLines';
+
+=head1 NAME
+
+Lintian::Data::Authority::VimPolicy - Lintian interface for manual references
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Authority::VimPolicy;
+
+=head1 DESCRIPTION
+
+Lintian::Data::Authority::VimPolicy provides a way to load data files for
+manual references.
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item title
+
+=item shorthand
+
+=item location
+
+=item separator
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Vim Policy'
+);
+
+has shorthand => (
+    is => 'rw',
+    default => 'vim-policy'
+);
+
+has location => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return 'authority/' . $self->shorthand;
+    }
+);
+
+has separator => (
+    is => 'rw',
+    default => sub { qr/::/ }
+);
+
+=item consumer
+
+=cut
+
+sub consumer {
+    my ($self, $key, $remainder, $previous) = @_;
+
+    return undef
+      if defined $previous;
+
+    my ($title, $url)= split($self->separator, $remainder, $TWO_PARTS);
+
+    my %entry;
+    $entry{title} = $title;
+    $entry{url} = $url;
+
+    return \%entry;
+}
+
+=item markdown_citation
+
+=cut
+
+sub markdown_citation {
+    my ($self, $section_key) = @_;
+
+    croak "Invalid section $section_key"
+      if $section_key eq $VOLUME_KEY;
+
+    my $volume_entry = $self->value($VOLUME_KEY);
+
+    # start with the citation to the overall manual.
+    my $volume_title = $volume_entry->{title};
+    my $volume_url   = $volume_entry->{url};
+
+    my $section_title;
+    my $section_url;
+
+    if ($self->recognizes($section_key)) {
+
+        my $section_entry = $self->value($section_key);
+
+        $section_title = $section_entry->{title};
+        $section_url   = $section_entry->{url};
+    }
+
+    return markdown_authority(
+        $volume_title, $volume_url,$section_key,
+        $section_title, $section_url
+    );
+}
+
+=item write_line
+
+=cut
+
+sub write_line {
+    my ($data_fd, $section_key, $section_title, $destination) = @_;
+
+    # drop final dots
+    $section_key =~ s{ [.]+ $}{}x;
+
+    # reduce consecutive whitespace
+    $section_title =~ s{ \s+ }{ }gx;
+
+    my $line= join($SEPARATOR,$section_key, $section_title, $destination);
+
+    say {$data_fd} encode_utf8($line);
+
+    return;
+}
+
+=item write_data_file
+
+=cut
+
+sub write_data_file {
+    my ($self, $basedir, $generated) = @_;
+
+    my $header =<<"HEADER";
+# Data about titles, sections, and URLs of manuals, used to expand references
+# in tag descriptions and add links for HTML output.  Each line of this file
+# has three fields separated by double colons:
+#
+#     <section> :: <title> :: <url>
+#
+# If <section> is an underscore, that line specifies the title and URL for the
+# whole manual.
+
+HEADER
+
+    my $data_path = "$basedir/" . $self->location;
+    my $parent_dir = path($data_path)->parent->stringify;
+    path($parent_dir)->mkpath
+      unless -e $parent_dir;
+
+    my $output = encode_utf8($header) . $generated;
+    path($data_path)->spew($output);
+
+    return;
+}
+
+=item find_installable_name
+
+=cut
+
+sub find_installable_name {
+    my ($self, $archive, $release, $liberty, $port, $requested_path) = @_;
+
+    my @installed_by;
+
+    # find installable package
+    for my $installable_architecture ('all', $port) {
+
+        my $local_path
+          = $archive->contents_gz($release, $liberty,
+            $installable_architecture);
+
+        open(my $fd, '<:gzip', $local_path)
+          or die encode_utf8("Cannot open $local_path.");
+
+        while (my $line = <$fd>) {
+
+            chomp $line;
+
+            my ($path, $finder) = split($SPACE, $line, 2);
+            next
+              unless length $path
+              && length $finder;
+
+            if ($path eq $requested_path) {
+
+                my $name = $1;
+
+                my @locations = split(m{,}, $finder);
+                for my $location (@locations) {
+
+                    my ($section, $installable)= split(m{/}, $location, 2);
+
+                    push(@installed_by, $installable);
+                }
+
+                next;
+            }
+        }
+
+        close $fd;
+    }
+
+    die encode_utf8(
+        "The path $requested_path is not installed by any package.")
+      if @installed_by < 1;
+
+    if (@installed_by > 1) {
+        warn encode_utf8(
+            "The path $requested_path is installed by multiple packages:\n");
+        warn encode_utf8($INDENT . "- $_\n")for @installed_by;
+    }
+
+    my $installable_name = shift @installed_by;
+
+    return $installable_name;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    # shipped as part of the vim installable
+    my $shipped_base = 'usr/share/doc/vim/vim-policy.html/';
+    my $index_name = 'index.html';
+
+    my $shipped_path = $shipped_base . $index_name;
+    my $stored_uri = "file:///$shipped_base";
+
+    # neutral sort order
+    local $ENV{LC_ALL} = 'C';
+
+    my $release = 'stable';
+    my $port = 'amd64';
+
+    my $installable_name
+      = $self->find_installable_name($archive, $release, 'main', $port,
+        $shipped_path);
+
+    my $deb822_by_installable_name
+      = $archive->deb822_packages_by_installable_name($release, 'main', $port);
+
+    my $work_folder
+      = Path::Tiny->tempdir(
+        TEMPLATE => 'refresh-doc-base-specification-XXXXXXXXXX');
+
+    die encode_utf8("Installable $installable_name not shipped in port $port")
+      unless exists $deb822_by_installable_name->{$installable_name};
+
+    my $deb822 = $deb822_by_installable_name->{$installable_name};
+
+    my $pool_path = $deb822->value('Filename');
+
+    my $deb_filename = basename($pool_path);
+    my $deb_local_path = "$work_folder/$deb_filename";
+    my $deb_url = $archive->mirror_base . $SLASH . $pool_path;
+
+    my $stderr;
+    run3([qw{wget --quiet}, "--output-document=$deb_local_path", $deb_url],
+        undef, \$stderr);
+    my $status = ($? >> $WAIT_STATUS_SHIFT);
+
+    # stderr already in UTF-8
+    die $stderr
+      if $status;
+
+    my $extract_folder = "$work_folder/unpacked/$pool_path";
+    path($extract_folder)->mkpath;
+
+    run3([qw{dpkg-deb --extract}, $deb_local_path, $extract_folder],
+        undef, \$stderr);
+    $status = ($? >> $WAIT_STATUS_SHIFT);
+
+    # stderr already in UTF-8
+    die $stderr
+      if $status;
+
+    unlink($deb_local_path)
+      or die encode_utf8("Cannot delete $deb_local_path");
+
+    my $generated;
+    open(my $memory_fd, '>', \$generated)
+      or die encode_utf8("Cannot open scalar: $!");
+
+    my $fresh_uri = URI::file->new_abs("/$extract_folder/$shipped_path");
+
+    my $parser = HTML::TokeParser::Simple->new(url => $fresh_uri);
+    my $in_title = 0;
+    my $in_dt_tag = 0;
+    my $after_a_tag = 0;
+
+    my $page_title = $EMPTY;
+    my $section_key = $EMPTY;
+    my $section_title = $EMPTY;
+    my $relative_destination = $EMPTY;
+
+    while (my $token = $parser->get_token) {
+
+        if (length $token->get_tag) {
+
+            if ($token->get_tag eq 'h1') {
+
+                $in_title = ($token->is_start_tag
+                      && $token->get_attr('class') eq 'title');
+
+                # not yet leaving title
+                next
+                  if $in_title;
+
+                # trim both ends
+                $page_title =~ s/^\s+|\s+$//g;
+
+                # underscore is a token for the whole page
+                write_line($memory_fd, $VOLUME_KEY, $page_title,
+                    $stored_uri . $index_name)
+                  if length $page_title;
+
+                $page_title = $EMPTY;
+            }
+
+            if ($token->get_tag eq 'dt') {
+
+                $in_dt_tag = $token->is_start_tag;
+
+                # not yet leaving dt tag
+                next
+                  if $in_dt_tag;
+
+                # trim both ends
+                $section_key =~ s/^\s+|\s+$//g;
+                $section_title =~ s/^\s+|\s+$//g;
+
+                my $full_destination = $stored_uri . $relative_destination;
+
+                write_line(
+                    $memory_fd, $section_key,
+                    $section_title,$full_destination
+                )if length $section_title;
+
+                $section_key = $EMPTY;
+                $section_title = $EMPTY;
+                $relative_destination = $EMPTY;
+            }
+
+            if ($token->get_tag eq 'a') {
+
+                $after_a_tag = $token->is_start_tag;
+
+                $relative_destination = $token->get_attr('href')
+                  if $token->is_start_tag;
+            }
+
+        } else {
+
+            # concatenate span objects
+            $page_title .= $token->as_is
+              if length $token->as_is
+              && $in_title
+              && $after_a_tag;
+
+            $section_key = $token->as_is
+              if length $token->as_is
+              && $in_dt_tag
+              && !$after_a_tag;
+
+            # concatenate span objects
+            $section_title .= $token->as_is
+              if length $token->as_is
+              && $in_dt_tag
+              && $after_a_tag;
+        }
+    }
+
+    close $memory_fd;
+
+    $self->write_data_file($basedir, $generated);
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Buildflags/Hardening.pm b/lib/Lintian/Data/Buildflags/Hardening.pm
new file mode 100644
index 0000000..75056df
--- /dev/null
+++ b/lib/Lintian/Data/Buildflags/Hardening.pm
@@ -0,0 +1,154 @@
+# -*- perl -*-
+
+# Copyright (C) 2011-2012 Niels Thykier <niels@thykier.net>
+#  - Based on a shell script by Raphael Geissert <atomo64@gmail.com>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Buildflags::Hardening;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(first_value uniq);
+use Unicode::UTF8 qw(decode_utf8);
+
+use Lintian::Deb822;
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Moo;
+use namespace::clean;
+
+const my $EMPTY => q{};
+const my $SLASH => q{/};
+
+const my $RECOMMENDED_FEATURES => q{recommended_features};
+
+with 'Lintian::Data::PreambledJSON';
+
+=encoding utf-8
+
+=head1 NAME
+
+Lintian::Data::Buildflags::Hardening -- Lintian API for hardening build flags
+
+=head1 SYNOPSIS
+
+ use Lintian::Data::Buildflags::Hardening;
+
+=head1 DESCRIPTION
+
+Lintian API for hardening build flags.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item title
+
+=item location
+
+=item recommended_features
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Hardening Flags from Dpkg'
+);
+
+has location => (
+    is => 'rw',
+    default => 'buildflags/hardening.json'
+);
+
+has recommended_features => (
+    is => 'rw',
+    default => sub { {} },
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); }
+);
+
+=item load
+
+=cut
+
+sub load {
+    my ($self, $search_space, $our_vendor) = @_;
+
+    my @candidates = map { $_ . $SLASH . $self->location } @{$search_space};
+    my $path = first_value { -e } @candidates;
+
+    my $recommended_features;
+    return 0
+      unless $self->read_file($path, \$recommended_features);
+
+    $self->recommended_features($recommended_features);
+
+    return 1;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    # find all recommended hardening features
+    local $ENV{LC_ALL} = 'C';
+    local $ENV{DEB_BUILD_MAINT_OPTIONS} = 'hardening=+all';
+
+    my @architectures
+      = split(/\n/, decode_utf8(safe_qx('dpkg-architecture', '-L')));
+    chomp for @architectures;
+
+    my %recommended_features;
+    for my $architecture (@architectures) {
+
+        local $ENV{DEB_HOST_ARCH} = $architecture;
+
+        my @command = qw{dpkg-buildflags --query-features hardening};
+        my $feature_output = decode_utf8(safe_qx(@command));
+
+        my $deb822 = Lintian::Deb822->new;
+        my @sections = $deb822->parse_string($feature_output);
+
+        my @enabled = grep { $_->value('Enabled') eq 'yes' } @sections;
+        my @features = uniq map { $_->value('Feature') } @enabled;
+
+        $recommended_features{$architecture} = [sort @features];
+    }
+
+    my $data_path = "$basedir/" . $self->location;
+    my $status
+      = $self->write_file($RECOMMENDED_FEATURES, \%recommended_features,
+        $data_path);
+
+    return $status;
+}
+
+=back
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Debhelper/Addons.pm b/lib/Lintian/Data/Debhelper/Addons.pm
new file mode 100644
index 0000000..3b8dbb1
--- /dev/null
+++ b/lib/Lintian/Data/Debhelper/Addons.pm
@@ -0,0 +1,215 @@
+# -*- perl -*-
+#
+# Copyright (C) 2008 by Raphael Geissert <atomo64@gmail.com>
+# Copyright (C) 2017-2018 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Debhelper::Addons;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use List::SomeUtils qw(first_value any uniq);
+use PerlIO::gzip;
+use Unicode::UTF8 qw(encode_utf8);
+
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+
+const my $WAIT_STATUS_SHIFT => 8;
+
+const my $ADD_ONS => 'add_ons';
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::PreambledJSON';
+
+=head1 NAME
+
+Lintian::Data::Debhelper::Addons - Lintian interface for debhelper addons.
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Debhelper::Addons;
+
+=head1 DESCRIPTION
+
+This module provides a way to load data files for debhelper.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item title
+
+=item location
+
+=item installable_names_by_add_on
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Debhelper Add-ons'
+);
+
+has location => (
+    is => 'rw',
+    default => 'debhelper/add_ons.json'
+);
+
+has installable_names_by_add_on => (is => 'rw', default => sub { {} });
+
+=item all
+
+=cut
+
+sub all {
+    my ($self) = @_;
+
+    return keys %{$self->installable_names_by_add_on};
+}
+
+=item installed_by
+
+=cut
+
+sub installed_by {
+    my ($self, $name) = @_;
+
+    return ()
+      unless exists $self->installable_names_by_add_on->{$name};
+
+    my @installed_by = @{$self->installable_names_by_add_on->{$name} // []};
+
+    push(@installed_by, 'debhelper-compat')
+      if any { $_ eq 'debhelper' } @installed_by;
+
+    return @installed_by;
+}
+
+=item load
+
+=cut
+
+sub load {
+    my ($self, $search_space, $our_vendor) = @_;
+
+    my @candidates = map { $_ . $SLASH . $self->location } @{$search_space};
+    my $path = first_value { -e } @candidates;
+
+    my $reference;
+    return 0
+      unless $self->read_file($path, \$reference);
+
+    my %add_ons = %{$reference // {}};
+    my %installable_names_by_add_on;
+
+    for my $name (keys %add_ons) {
+
+        my @installable_names;
+        push(@installable_names, @{$add_ons{$name}{installed_by}});
+
+        $installable_names_by_add_on{$name} = \@installable_names;
+    }
+
+    $self->installable_names_by_add_on(\%installable_names_by_add_on);
+
+    return 1;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    # neutral sort order
+    local $ENV{LC_ALL} = 'C';
+
+    my $port = 'amd64';
+
+    my %add_ons;
+
+    for my $installable_architecture ('all', $port) {
+
+        my $local_path
+          = $archive->contents_gz('sid', 'main', $installable_architecture);
+
+        open(my $fd, '<:gzip', $local_path)
+          or die encode_utf8("Cannot open $local_path.");
+
+        while (my $line = <$fd>) {
+
+            chomp $line;
+
+            my ($path, $finder) = split($SPACE, $line, 2);
+            next
+              unless length $path
+              && length $finder;
+
+            if ($path
+                =~ m{^ usr/share/perl5/Debian/Debhelper/Sequence/ (\S+) [.]pm $}x
+            ) {
+
+                my $name = $1;
+
+                my @locations = split(m{,}, $finder);
+                for my $location (@locations) {
+
+                    my ($section, $installable)= split(m{/}, $location, 2);
+
+                    $add_ons{$name}{installed_by} //= [];
+                    push(@{$add_ons{$name}{installed_by}}, $installable);
+                }
+
+                next;
+            }
+        }
+
+        close $fd;
+    }
+
+    my $data_path = "$basedir/" . $self->location;
+    my $status = $self->write_file($ADD_ONS, \%add_ons,$data_path);
+
+    return $status;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Debhelper/Commands.pm b/lib/Lintian/Data/Debhelper/Commands.pm
new file mode 100644
index 0000000..bd1ea67
--- /dev/null
+++ b/lib/Lintian/Data/Debhelper/Commands.pm
@@ -0,0 +1,306 @@
+# -*- perl -*-
+#
+# Copyright (C) 2008 by Raphael Geissert <atomo64@gmail.com>
+# Copyright (C) 2017-2018 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Debhelper::Commands;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use File::Basename;
+use IPC::Run3;
+use List::SomeUtils qw(first_value any uniq);
+use Path::Tiny;
+use PerlIO::gzip;
+use Unicode::UTF8 qw(encode_utf8);
+
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+
+const my $WAIT_STATUS_SHIFT => 8;
+
+const my $COMMANDS => 'commands';
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::PreambledJSON';
+
+=head1 NAME
+
+Lintian::Data::Debhelper::Commands - Lintian interface for debhelper commands.
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Debhelper::Commands;
+
+=head1 DESCRIPTION
+
+This module provides a way to load data files for debhelper.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item title
+
+=item location
+
+=item installable_names_by_command
+
+=item maint_commands
+
+=item misc_depends_commands
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Debhelper Commands'
+);
+
+has location => (
+    is => 'rw',
+    default => 'debhelper/commands.json'
+);
+
+has installable_names_by_command => (is => 'rw', default => sub { {} });
+has maint_commands => (is => 'rw', default => sub { [] });
+has misc_depends_commands => (is => 'rw', default => sub { [] });
+
+=item all
+
+=cut
+
+sub all {
+    my ($self) = @_;
+
+    return keys %{$self->installable_names_by_command};
+}
+
+=item installed_by
+
+=cut
+
+sub installed_by {
+    my ($self, $name) = @_;
+
+    return ()
+      unless exists $self->installable_names_by_command->{$name};
+
+    my @installed_by = @{$self->installable_names_by_command->{$name} // []};
+
+    push(@installed_by, 'debhelper-compat')
+      if any { $_ eq 'debhelper' } @installed_by;
+
+    return @installed_by;
+}
+
+=item load
+
+=cut
+
+sub load {
+    my ($self, $search_space, $our_vendor) = @_;
+
+    my @candidates = map { $_ . $SLASH . $self->location } @{$search_space};
+    my $path = first_value { -e } @candidates;
+
+    my $reference;
+    return 0
+      unless $self->read_file($path, \$reference);
+
+    my %commands = %{$reference // {}};
+
+    my %installable_names_by_command;
+    my @maint_commands;
+    my @misc_depends_commands;
+
+    for my $name (keys %commands) {
+
+        my @installable_names;
+        push(@installable_names, @{$commands{$name}{installed_by}});
+
+        $installable_names_by_command{$name} = \@installable_names;
+
+        push(@maint_commands, $name)
+          if $commands{$name}{uses_autoscript};
+
+        push(@misc_depends_commands, $name)
+          if $commands{$name}{uses_misc_depends}
+          && $name ne 'dh_gencontrol';
+    }
+
+    $self->installable_names_by_command(\%installable_names_by_command);
+    $self->maint_commands(\@maint_commands);
+    $self->misc_depends_commands(\@misc_depends_commands);
+
+    return 1;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    # neutral sort order
+    local $ENV{LC_ALL} = 'C';
+
+    my $port = 'amd64';
+
+    my %commands;
+
+    for my $installable_architecture ('all', $port) {
+
+        my $local_path
+          = $archive->contents_gz('sid', 'main', $installable_architecture);
+
+        open(my $fd, '<:gzip', $local_path)
+          or die encode_utf8("Cannot open $local_path.");
+
+        while (my $line = <$fd>) {
+
+            chomp $line;
+
+            my ($path, $finder) = split($SPACE, $line, 2);
+            next
+              unless length $path
+              && length $finder;
+
+            if ($path =~ m{^ usr/bin/ (dh_ \S+) $}x) {
+
+                my $name = $1;
+
+                my @locations = split(m{,}, $finder);
+                for my $location (@locations) {
+
+                    my ($section, $installable)= split(m{/}, $location, 2);
+
+                    $commands{$name}{installed_by} //= [];
+                    push(@{$commands{$name}{installed_by}}, $installable);
+                }
+
+                next;
+            }
+        }
+
+        close $fd;
+    }
+
+    my $deb822_by_installable_name
+      = $archive->deb822_packages_by_installable_name('sid', 'main', $port);
+
+    my $work_folder
+      = Path::Tiny->tempdir(
+        TEMPLATE => 'refresh-debhelper-add-ons-XXXXXXXXXX');
+
+    my @uses_autoscript;
+    my @uses_misc_depends;
+
+    my @installable_names= uniq map { @{$_->{installed_by}} }values %commands;
+
+    for my $installable_name (sort @installable_names) {
+
+        next
+          unless exists $deb822_by_installable_name->{$installable_name};
+
+        my $deb822 = $deb822_by_installable_name->{$installable_name};
+
+        my $pool_path = $deb822->value('Filename');
+
+        my $deb_filename = basename($pool_path);
+        my $deb_local_path = "$work_folder/$deb_filename";
+        my $deb_url = $archive->mirror_base . $SLASH . $pool_path;
+
+        my $stderr;
+        run3(
+            [qw{wget --quiet}, "--output-document=$deb_local_path", $deb_url],
+            undef, \$stderr
+        );
+        my $status = ($? >> $WAIT_STATUS_SHIFT);
+
+        # stderr already in UTF-8
+        die $stderr
+          if $status;
+
+        my $extract_folder = "$work_folder/pool/$pool_path";
+        path($extract_folder)->mkpath;
+
+        run3([qw{dpkg-deb --extract}, $deb_local_path, $extract_folder],
+            undef, \$stderr);
+        $status = ($? >> $WAIT_STATUS_SHIFT);
+
+        # stderr already in UTF-8
+        die $stderr
+          if $status;
+
+        unlink($deb_local_path)
+          or die encode_utf8("Cannot delete $deb_local_path");
+
+        my $autoscript_rule = File::Find::Rule->file;
+        $autoscript_rule->name(qr{^dh_});
+        $autoscript_rule->grep(qr{autoscript});
+        my @autoscript_matches
+          = $autoscript_rule->in("$extract_folder/usr/bin");
+
+        push(@uses_autoscript, map { basename($_) } @autoscript_matches);
+
+        my $misc_depends_rule = File::Find::Rule->file;
+        $misc_depends_rule->name(qr{^dh_});
+        $misc_depends_rule->grep(qr{misc:Depends});
+        my @misc_depends_matches
+          = $misc_depends_rule->in("$extract_folder/usr/bin");
+
+        push(@uses_misc_depends, map { basename($_) } @misc_depends_matches);
+
+        path("$work_folder/pool")->remove_tree;
+    }
+
+    $commands{$_}{uses_autoscript} = 1 for @uses_autoscript;
+
+    $commands{$_}{uses_misc_depends} = 1 for @uses_misc_depends;
+
+    my $data_path = "$basedir/" . $self->location;
+    my $status = $self->write_file($COMMANDS, \%commands,$data_path);
+
+    return $status;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Debhelper/Levels.pm b/lib/Lintian/Data/Debhelper/Levels.pm
new file mode 100644
index 0000000..571ce2c
--- /dev/null
+++ b/lib/Lintian/Data/Debhelper/Levels.pm
@@ -0,0 +1,89 @@
+# -*- perl -*-
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Debhelper::Levels;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::JoinedLines';
+
+=head1 NAME
+
+Lintian::Data::Debhelper::Levels - Lintian interface for debhelper
+compat levels.
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Debhelper::Levels;
+
+=head1 DESCRIPTION
+
+This module provides a way to load data files for debhelper.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item title
+
+=item location
+
+=item separator
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Debhelper Levels'
+);
+
+has location => (
+    is => 'rw',
+    default => 'debhelper/compat-level'
+);
+
+has separator => (
+    is => 'rw',
+    default => sub { qr/=/ }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Fonts.pm b/lib/Lintian/Data/Fonts.pm
new file mode 100644
index 0000000..4820439
--- /dev/null
+++ b/lib/Lintian/Data/Fonts.pm
@@ -0,0 +1,216 @@
+# -*- perl -*-
+#
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Fonts;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use File::Basename;
+use List::SomeUtils qw(first_value uniq);
+use PerlIO::gzip;
+use Unicode::UTF8 qw(encode_utf8);
+
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+
+const my $FONTS => 'fonts';
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::PreambledJSON';
+
+=head1 NAME
+
+Lintian::Data::Fonts - Lintian interface for fonts.
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Fonts;
+
+=head1 DESCRIPTION
+
+This module provides a way to load data files for fonts.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item title
+
+=item location
+
+=item installable_names_by_font
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Fonts Available for Installation'
+);
+
+has location => (
+    is => 'rw',
+    default => 'fonts.json'
+);
+
+has installable_names_by_font => (is => 'rw', default => sub { {} });
+
+=item all
+
+=cut
+
+sub all {
+    my ($self) = @_;
+
+    return keys %{$self->installable_names_by_font};
+}
+
+=item installed_by
+
+=cut
+
+sub installed_by {
+    my ($self, $name) = @_;
+
+    my $lowercase = lc $name;
+
+    return ()
+      unless exists $self->installable_names_by_font->{$lowercase};
+
+    my @installed_by = @{$self->installable_names_by_font->{$lowercase} // []};
+
+    return @installed_by;
+}
+
+=item load
+
+=cut
+
+sub load {
+    my ($self, $search_space, $our_vendor) = @_;
+
+    my @candidates = map { $_ . $SLASH . $self->location } @{$search_space};
+    my $path = first_value { -e } @candidates;
+
+    my $reference;
+    return 0
+      unless $self->read_file($path, \$reference);
+
+    my %fonts = %{$reference // {}};
+    my %installable_names_by_font;
+
+    for my $name (keys %fonts) {
+
+        my @installable_names;
+        push(@installable_names, @{$fonts{$name}{installed_by}});
+
+        $installable_names_by_font{$name} = \@installable_names;
+    }
+
+    $self->installable_names_by_font(\%installable_names_by_font);
+
+    return 1;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    # neutral sort order
+    local $ENV{LC_ALL} = 'C';
+
+    my $port = 'amd64';
+
+    my %fonts;
+
+    for my $installable_architecture ('all', $port) {
+
+        my $local_path
+          = $archive->contents_gz('sid', 'main', $installable_architecture);
+
+        open(my $fd, '<:gzip', $local_path)
+          or die encode_utf8("Cannot open $local_path.");
+
+        while (my $line = <$fd>) {
+
+            chomp $line;
+
+            my ($path, $finder) = split($SPACE, $line, 2);
+            next
+              unless length $path
+              && length $finder;
+
+            if ($path =~ m{ [.] (?:[to]tf|pfb) $}ix) {
+
+                my @locations = split(m{,}, $finder);
+                for my $location (@locations) {
+
+                    my ($section, $installable_name)
+                      = split(m{/}, $location, 2);
+
+        # Record only packages starting with ttf-, otf-, t1-, xfonts- or fonts-
+                    next
+                      unless $installable_name
+                      =~ m{^ (?: [to]tf | t1 | x?fonts ) - }x;
+
+                    my $basename = basename($path);
+                    my $lowercase = lc $basename;
+
+                    $fonts{$lowercase}{installed_by} //= [];
+                    push(@{$fonts{$lowercase}{installed_by}},
+                        $installable_name);
+                }
+
+                next;
+            }
+        }
+
+        close $fd;
+    }
+
+    my $data_path = "$basedir/" . $self->location;
+    my $status = $self->write_file($FONTS, \%fonts,$data_path);
+
+    return $status;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/InitD/VirtualFacilities.pm b/lib/Lintian/Data/InitD/VirtualFacilities.pm
new file mode 100644
index 0000000..fbb4030
--- /dev/null
+++ b/lib/Lintian/Data/InitD/VirtualFacilities.pm
@@ -0,0 +1,256 @@
+# -*- perl -*-
+#
+# Copyright (C) 2008, 2010 by Raphael Geissert <atomo64@gmail.com>
+# Copyright (C) 2017 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::InitD::VirtualFacilities;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use File::Basename;
+use IPC::Run3;
+use List::SomeUtils qw(first_value uniq);
+use Path::Tiny;
+use PerlIO::gzip;
+use Unicode::UTF8 qw(encode_utf8);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $DOLLAR => q{$};
+
+const my $NEWLINE => qq{\n};
+
+const my $WAIT_STATUS_SHIFT => 8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::JoinedLines';
+
+=head1 NAME
+
+Lintian::Data::InitD::VirtualFacilities - Lintian interface for init.d virtual facilities
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::InitD::VirtualFacilities;
+
+=head1 DESCRIPTION
+
+This module provides a way to load data files for init.d.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item title
+
+=item location
+
+=item separator
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Init.d Virtual Facilities'
+);
+
+has location => (
+    is => 'rw',
+    default => 'init.d/virtual_facilities'
+);
+
+has separator => (
+    is => 'rw',
+    default => sub { qr{ \s+ }x }
+);
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    # neutral sort order
+    local $ENV{LC_ALL} = 'C';
+
+    my $port = 'amd64';
+
+    my %paths_by_installable_names;
+
+    for my $installable_architecture ('all', $port) {
+
+        my $local_path
+          = $archive->contents_gz('sid', 'main', $installable_architecture);
+
+        open(my $fd, '<:gzip', $local_path)
+          or die encode_utf8("Cannot open $local_path.");
+
+        while (my $line = <$fd>) {
+
+            chomp $line;
+
+            my ($path, $finder) = split($SPACE, $line, 2);
+            next
+              unless length $path
+              && length $finder;
+
+            # catch both monolithic and split configurations
+            if ($path =~ m{^ etc/insserv[.]conf (?: $ | [.]d / )? }x) {
+
+                my @locations = split(m{,}, $finder);
+                for my $location (@locations) {
+
+                    my ($section, $installable)= split(m{/}, $location, 2);
+
+                    $paths_by_installable_names{$installable} //= [];
+                    push(@{$paths_by_installable_names{$installable}}, $path);
+                }
+
+                next;
+            }
+        }
+
+        close $fd;
+    }
+
+    my $deb822_by_installable_name
+      = $archive->deb822_packages_by_installable_name('sid', 'main', $port);
+
+    my $work_folder
+      = Path::Tiny->tempdir(
+        TEMPLATE => 'refresh-debhelper-add-ons-XXXXXXXXXX');
+
+    my @virtual_facilities;
+
+    my @installable_names = keys %paths_by_installable_names;
+
+    for my $installable_name (sort @installable_names) {
+
+        next
+          unless exists $deb822_by_installable_name->{$installable_name};
+
+        my $deb822 = $deb822_by_installable_name->{$installable_name};
+
+        my $pool_path = $deb822->value('Filename');
+
+        my $deb_filename = basename($pool_path);
+        my $deb_local_path = "$work_folder/$deb_filename";
+        my $deb_url = $archive->mirror_base . $SLASH . $pool_path;
+
+        my $stderr;
+        run3(
+            [qw{wget --quiet}, "--output-document=$deb_local_path", $deb_url],
+            undef, \$stderr
+        );
+        my $status = ($? >> $WAIT_STATUS_SHIFT);
+
+        # stderr already in UTF-8
+        die $stderr
+          if $status;
+
+        my $extract_folder = "$work_folder/pool/$pool_path";
+        path($extract_folder)->mkpath;
+
+        run3([qw{dpkg-deb --extract}, $deb_local_path, $extract_folder],
+            undef, \$stderr);
+        $status = ($? >> $WAIT_STATUS_SHIFT);
+
+        # stderr already in UTF-8
+        die $stderr
+          if $status;
+
+        unlink($deb_local_path)
+          or die encode_utf8("Cannot delete $deb_local_path");
+
+        my $monolithic_rule = File::Find::Rule->file;
+        $monolithic_rule->name('insserv.conf');
+        my @files= $monolithic_rule->in("$extract_folder/etc");
+
+        my $split_files_rule = File::Find::Rule->file;
+        push(@files,
+            $split_files_rule->in("$extract_folder/etc/insserv.conf.d"));
+
+        for my $path (@files) {
+
+            open(my $fd, '<', $path)
+              or die encode_utf8("Cannot open $path.");
+
+            while (my $line = <$fd>) {
+
+                if ($line =~ m{^ ( \$\S+ ) }x) {
+
+                    my $virtual = $1;
+                    push(@virtual_facilities, $virtual);
+                }
+            }
+
+            close $fd;
+        }
+
+        path("$work_folder/pool")->remove_tree;
+    }
+
+    push(@virtual_facilities, $DOLLAR . 'all');
+
+    my $generated = $EMPTY;
+
+    # still in UTF-8
+    $generated .= $_ . $NEWLINE for sort +uniq @virtual_facilities;
+
+    my $header =<<"HEADER";
+# The list of known virtual facilities that init scripts may depend on.
+#
+
+HEADER
+
+    my $data_path = "$basedir/" . $self->location;
+    my $parent_dir = path($data_path)->parent->stringify;
+    path($parent_dir)->mkpath
+      unless -e $parent_dir;
+
+    my $output = encode_utf8($header) . $generated;
+    path($data_path)->spew($output);
+
+    return 1;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/JoinedLines.pm b/lib/Lintian/Data/JoinedLines.pm
new file mode 100644
index 0000000..a753430
--- /dev/null
+++ b/lib/Lintian/Data/JoinedLines.pm
@@ -0,0 +1,369 @@
+# -*- perl -*-
+# Lintian::Data::JoinedLines -- interface to query lists of keywords
+
+# Copyright (C) 2008 Russ Allbery
+# Copyright (C) 2017-2018 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::JoinedLines;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(carp croak);
+use Const::Fast;
+use List::SomeUtils qw(any);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo::Role;
+use namespace::clean;
+
+const my $EMPTY => q{};
+const my $SLASH => q{/};
+
+=head1 NAME
+
+Lintian::Data::JoinedLines - Lintian interface to query lists of keywords
+
+=head1 SYNOPSIS
+
+    my $keyword;
+    my $list = Lintian::Data::JoinedLines->new('type');
+    if ($list->recognizes($keyword)) {
+        # do something ...
+    }
+    my $hash = Lintian::Data::JoinedLines->new('another-type', qr{\s++});
+    if ($hash->value($keyword) > 1) {
+        # do something ...
+    }
+    if ($list->value($keyword) > 1) {
+        # do something ...
+    }
+    my @keywords = $list->all;
+    if ($list->matches_any($keyword)) {
+        # do something ...
+    }
+
+=head1 DESCRIPTION
+
+Lintian::Data::JoinedLines provides a way of loading a list of keywords or key/value
+pairs from a file in the Lintian root and then querying that list.
+The lists are stored in the F<data> directory of the Lintian root and
+consist of one keyword or key/value pair per line.  Blank lines and
+lines beginning with C<#> are ignored.  Leading and trailing whitespace
+is stripped.
+
+If requested, the lines are split into key/value pairs with a given
+separator regular expression.  Otherwise, keywords are taken verbatim
+as they are listed in the file and may include spaces.
+
+This module allows lists such as menu sections, doc-base sections,
+obsolete packages, package fields, and so forth to be stored in simple,
+easily editable files.
+
+NB: By default Lintian::Data::JoinedLines is lazy and defers loading of the data
+file until it is actually needed.
+
+=head2 Interface for the CODE argument
+
+This section describes the interface between for the CODE argument
+for the class method new.
+
+The sub will be called once for each key/pair with three arguments,
+KEY, VALUE and CURVALUE.  The first two are the key/value pair parsed
+from the data file and CURVALUE is current value associated with the
+key.  CURVALUE will be C<undef> the first time the sub is called with
+that KEY argument.
+
+The sub can then modify VALUE in some way and return the new value for
+that KEY.  If CURVALUE is not C<undef>, the sub may return C<undef> to
+indicate that the current value should still be used.  It is not
+permissible for the sub to return C<undef> if CURVALUE is C<undef>.
+
+Where Perl semantics allow it, the sub can modify CURVALUE and the
+changes will be reflected in the result.  As an example, if CURVALUE
+is a hashref, new keys can be inserted etc.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item dataset
+
+=item C<keyorder>
+
+=cut
+
+has dataset => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+has keyorder => (
+    is => 'rw',
+    coerce => sub { my ($arrayref) = @_; return ($arrayref // []); },
+    default => sub { [] }
+);
+
+=item all
+
+Returns all keywords listed in the data file as a list in original order.
+In a scalar context, returns the number of keywords.
+
+=cut
+
+sub all {
+    my ($self) = @_;
+
+    return @{$self->keyorder};
+}
+
+=item recognizes (KEY)
+
+Returns true if KEY was listed in the data file represented by this
+Lintian::Data::JoinedLines instance and false otherwise.
+
+=cut
+
+sub recognizes {
+    my ($self, $key) = @_;
+
+    return 0
+      unless length $key;
+
+    return 1
+      if exists $self->dataset->{$key};
+
+    return 0;
+}
+
+=item resembles (KEY)
+
+Returns true if the data file contains a key that is a case-insensitive match
+to KEY, and false otherwise.
+
+=cut
+
+sub resembles {
+    my ($self, $key) = @_;
+
+    return 0
+      unless length $key;
+
+    return 1
+      if $self->recognizes($key);
+
+    return 1
+      if any { m{^\Q$key\E$}i } keys %{$self->dataset};
+
+    return 0;
+}
+
+=item value (KEY)
+
+Returns the value attached to KEY if it was listed in the data
+file represented by this Lintian::Data::JoinedLines instance and the undefined value
+otherwise.
+
+=cut
+
+sub value {
+    my ($self, $key) = @_;
+
+    return undef
+      unless length $key;
+
+    return $self->dataset->{$key};
+}
+
+=item matches_any(KEYWORD[, MODIFIERS])
+
+Returns true if KEYWORD matches any regular expression listed in the
+data file. The optional MODIFIERS serve as modifiers on all regexes.
+
+=cut
+
+sub matches_any {
+    my ($self, $wanted, $modifiers) = @_;
+
+    return 0
+      unless length $wanted;
+
+    $modifiers //= $EMPTY;
+
+    return 1
+      if any { $wanted =~ /(?$modifiers)$_/ } $self->all;
+
+    return 0;
+}
+
+=item load
+
+=cut
+
+sub load {
+    my ($self, $search_space, $our_vendor) = @_;
+
+    my @remaining_lineage = @{$search_space // []};
+    unless (@remaining_lineage) {
+
+        carp encode_utf8('Unknown data file: ' . $self->location);
+        return 0;
+    }
+
+    my $directory = shift @remaining_lineage;
+
+    my $path = $directory . $SLASH . $self->location;
+
+    return $self->load(\@remaining_lineage, $our_vendor)
+      unless -e $path;
+
+    open(my $fd, '<:utf8_strict', $path)
+      or die encode_utf8("Cannot open $path: $!");
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        # trim both ends
+        $line =~ s/^\s+|\s+$//g;
+
+        next
+          unless length $line;
+
+        next
+          if $line =~ m{^\#};
+
+        # a command
+        if ($line =~ s/^\@//) {
+
+            my ($directive, $value) = split(/\s+/, $line, 2);
+            if ($directive eq 'delete') {
+
+                croak encode_utf8(
+                    "Missing key after \@delete in $path at line $position")
+                  unless length $value;
+
+                @{$self->keyorder} = grep { $_ ne $value } @{$self->keyorder};
+                delete $self->dataset->{$value};
+
+            } elsif ($directive eq 'include-parent') {
+
+                $self->load(\@remaining_lineage, $our_vendor)
+                  or croak encode_utf8("No ancestor data file for $path");
+
+            } elsif ($directive eq 'if-vendor-is'
+                || $directive eq 'if-vendor-is-not') {
+
+                my ($specified_vendor, $remain) = split(/\s+/, $value, 2);
+
+                croak encode_utf8("Missing vendor name after \@$directive")
+                  unless length $specified_vendor;
+                croak encode_utf8(
+                    "Missing command after vendor name for \@$directive")
+                  unless length $remain;
+
+                $our_vendor =~ s{/.*$}{};
+
+                next
+                  if $directive eq 'if-vendor-is'
+                  && $our_vendor ne $specified_vendor;
+
+                next
+                  if $directive eq 'if-vendor-is-not'
+                  && $our_vendor eq $specified_vendor;
+
+                $line = $remain;
+                redo;
+
+            } else {
+                croak encode_utf8(
+                    "Unknown operation \@$directive in $path at line $position"
+                );
+            }
+            next;
+        }
+
+        my $key = $line;
+        my $remainder;
+
+        ($key, $remainder) = split($self->separator, $line, 2)
+          if defined $self->separator;
+
+        # do not autovivify; 'exists' below
+        my $previous;
+        $previous = $self->dataset->{$key}
+          if exists $self->dataset->{$key};
+
+        my $value;
+        if ($self->can('consumer')) {
+
+            $value = $self->consumer($key, $remainder, $previous);
+            next
+              unless defined $value;
+
+        } else {
+            $value = $remainder;
+        }
+
+        push(@{$self->keyorder}, $key)
+          unless exists $self->dataset->{$key};
+
+        $self->dataset->{$key} = $value;
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return 1;
+}
+
+=back
+
+=head1 FILES
+
+=over 4
+
+=item LINTIAN_INCLUDE_DIR/data
+
+The files loaded by this module must be located in this directory.
+Relative paths containing a C</> are permitted, so files may be organized
+in subdirectories in this directory.
+
+Note that lintian supports multiple LINTIAN_INCLUDE_DIRs.
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Russ Allbery <rra@debian.org> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1), L<https://lintian.debian.org/manual/section-2.6.html>
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Policy/Releases.pm b/lib/Lintian/Data/Policy/Releases.pm
new file mode 100644
index 0000000..540da13
--- /dev/null
+++ b/lib/Lintian/Data/Policy/Releases.pm
@@ -0,0 +1,274 @@
+# -*- perl -*-
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Policy::Releases;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Date::Parse qw(str2time);
+use List::SomeUtils qw(first_value);
+use IPC::Run3;
+use HTTP::Tiny;
+use List::SomeUtils qw(minmax);
+use List::UtilsBy qw(rev_nsort_by);
+use Path::Tiny;
+use Time::Moment;
+use Unicode::UTF8 qw(decode_utf8 encode_utf8);
+
+const my $SLASH => q{/};
+
+const my $RELEASES => q{releases};
+
+const my $WAIT_STATUS_SHIFT => 8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::PreambledJSON';
+
+=head1 NAME
+
+Lintian::Data::Policy::Releases - Lintian interface for policy releases
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Policy::Releases;
+
+=head1 DESCRIPTION
+
+This module provides a way to load data files for policy releases.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item title
+
+=item location
+
+=item ordered_versions
+
+=item by_version
+
+=item max_dots
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Debian Policy Releases'
+);
+
+has location => (
+    is => 'rw',
+    default => 'debian-policy/releases.json'
+);
+
+has ordered_versions => (is => 'rw', default => sub { [] });
+has by_version => (is => 'rw', default => sub { {} });
+has max_dots => (is => 'rw');
+
+=item latest_version
+
+=cut
+
+sub latest_version {
+    my ($self) = @_;
+
+    return $self->ordered_versions->[0];
+}
+
+=item normalize
+
+=cut
+
+sub normalize {
+    my ($self, $version) = @_;
+
+    my $have = $version =~ tr{\.}{};
+    my $need = $self->max_dots - $have;
+
+    $version .= '.0' for (1..$need);
+
+    return $version;
+}
+
+=item is_known
+
+=cut
+
+sub is_known {
+    my ($self, $version) = @_;
+
+    my $normalized = $self->normalize($version);
+
+    return exists $self->by_version->{$normalized};
+}
+
+=item epoch
+
+=cut
+
+sub epoch {
+    my ($self, $version) = @_;
+
+    my $normalized = $self->normalize($version);
+
+    my $release = $self->by_version->{$normalized};
+    return undef
+      unless defined $release;
+
+    return $release->{epoch};
+}
+
+=item author
+
+=cut
+
+sub author {
+    my ($self, $version) = @_;
+
+    my $normalized = $self->normalize($version);
+
+    my $release = $self->by_version->{$normalized};
+    return undef
+      unless defined $release;
+
+    return $release->{author};
+}
+
+=item load
+
+=cut
+
+sub load {
+    my ($self, $search_space, $our_vendor) = @_;
+
+    my @candidates = map { $_ . $SLASH . $self->location } @{$search_space};
+    my $path = first_value { -e } @candidates;
+
+    my $reference;
+    return 0
+      unless $self->read_file($path, \$reference);
+
+    my @releases = @{$reference // []};
+
+    my @sorted = rev_nsort_by { $_->{epoch} } @releases;
+    my @ordered_versions = map { $_->{version} } @sorted;
+    $self->ordered_versions(\@ordered_versions);
+
+    my @dot_count = map { tr{\.}{} } @ordered_versions;
+    my (undef, $max_dots) = minmax @dot_count;
+    $self->max_dots($max_dots);
+
+    # normalize versions
+    $_->{version} = $self->normalize($_->{version}) for @releases;
+
+    my %by_version;
+    $by_version{$_->{version}} = $_ for @releases;
+
+    $self->by_version(\%by_version);
+
+    return 1;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    my $changelog_url
+      = 'https://salsa.debian.org/dbnpolicy/policy/-/raw/master/debian/changelog?inline=false';
+
+    my $response = HTTP::Tiny->new->get($changelog_url);
+    die encode_utf8("Failed to get $changelog_url!\n")
+      unless $response->{success};
+
+    my $tempfile_tiny = Path::Tiny->tempfile;
+    $tempfile_tiny->spew($response->{content});
+
+    my @command = (
+        qw{dpkg-parsechangelog --format rfc822 --all --file},
+        $tempfile_tiny->stringify
+    );
+    my $rfc822;
+    my $stderr;
+    run3(\@command, \undef, \$rfc822, \$stderr);
+    my $dpkg_status = ($? >> $WAIT_STATUS_SHIFT);
+
+    # already in UTF-8
+    die $stderr
+      if $dpkg_status;
+
+    my $deb822 = Lintian::Deb822->new;
+    my @sections = $deb822->parse_string(decode_utf8($rfc822));
+
+    my @releases;
+    for my $section (@sections) {
+
+        my $epoch = str2time($section->value('Date'), 'GMT');
+        my $moment = Time::Moment->from_epoch($epoch);
+        my $timestamp = $moment->strftime('%Y-%m-%dT%H:%M:%S%Z');
+
+        my @closes = sort { $a <=> $b } $section->trimmed_list('Closes');
+        my @changes = split(/\n/, $section->text('Changes'));
+
+        my %release;
+        $release{version} = $section->value('Version');
+        $release{timestamp} = $timestamp;
+        $release{epoch} = $epoch;
+        $release{closes} = \@closes;
+        $release{changes} = \@changes;
+        $release{author} = $section->value('Maintainer');
+
+        push(@releases, \%release);
+    }
+
+    my @sorted = rev_nsort_by { $_->{epoch} } @releases;
+
+    my $data_path = "$basedir/" . $self->location;
+    my $write_status = $self->write_file($RELEASES, \@releases, $data_path);
+
+    return $write_status;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/PreambledJSON.pm b/lib/Lintian/Data/PreambledJSON.pm
new file mode 100644
index 0000000..e2af970
--- /dev/null
+++ b/lib/Lintian/Data/PreambledJSON.pm
@@ -0,0 +1,164 @@
+# -*- perl -*-
+
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::PreambledJSON;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(carp);
+use Const::Fast;
+use JSON::MaybeXS;
+use Path::Tiny;
+use Time::Piece;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo::Role;
+use namespace::clean;
+
+const my $EMPTY => q{};
+
+const my $PREAMBLE => q{preamble};
+const my $TITLE => q{title};
+const my $CARGO => q{cargo};
+
+=encoding utf-8
+
+=head1 NAME
+
+Lintian::Data::PreambledJSON -- Data in preambled JSON format
+
+=head1 SYNOPSIS
+
+ use Lintian::Data::PreambledJSON;
+
+=head1 DESCRIPTION
+
+Routines for access and management of preambled JSON data files.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item last_modified
+
+=cut
+
+has cargo => (
+    is => 'rw',
+    coerce => sub { my ($scalar) = @_; return ($scalar // $EMPTY); }
+);
+
+=item read_file
+
+=cut
+
+sub read_file {
+    my ($self, $path, $double_reference) = @_;
+
+    if (!length $path || !-e $path) {
+
+        carp encode_utf8("Unknown data file: $path");
+        return 0;
+    }
+
+    my $json = path($path)->slurp;
+    my $data = decode_json($json);
+
+    my %preamble = %{$data->{$PREAMBLE}};
+    my $stored_title = $preamble{$TITLE};
+    my $storage_key = $preamble{$CARGO};
+
+    unless (length $stored_title && length $storage_key) {
+        warn encode_utf8("Please refresh data file $path: invalid format");
+        return 0;
+    }
+
+    unless ($stored_title eq $self->title) {
+        warn encode_utf8(
+            "Please refresh data file $path: wrong title $stored_title");
+        return 0;
+    }
+
+    if ($storage_key eq $PREAMBLE) {
+        warn encode_utf8(
+            "Please refresh data file $path: disallowed cargo key $storage_key"
+        );
+        return 0;
+    }
+
+    if (!exists $data->{$storage_key}) {
+        warn encode_utf8(
+            "Please refresh data file $path: cargo key $storage_key not found"
+        );
+        return 0;
+    }
+
+    ${$double_reference} = $data->{$storage_key};
+
+    return 1;
+}
+
+=item write_file
+
+=cut
+
+sub write_file {
+    my ($self, $storage_key, $reference, $path) = @_;
+
+    die
+"Cannot write preambled JSON data file $path: disallowed cargo key $storage_key"
+      if $storage_key eq $PREAMBLE;
+
+    my %preamble;
+    $preamble{$TITLE} = $self->title;
+    $preamble{$CARGO} = $storage_key;
+
+    my %combined;
+    $combined{$PREAMBLE} = \%preamble;
+    $combined{$storage_key} = $reference;
+
+    # convert to UTF-8 prior to encoding in JSON
+    my $encoder = JSON->new;
+    $encoder->canonical;
+    $encoder->utf8;
+    $encoder->pretty;
+
+    my $json = $encoder->encode(\%combined);
+
+    my $parentdir = path($path)->parent->stringify;
+    path($parentdir)->mkpath
+      unless -e $parentdir;
+
+    # already in UTF-8
+    path($path)->spew($json);
+
+    return 1;
+}
+
+=back
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Provides/MailTransportAgent.pm b/lib/Lintian/Data/Provides/MailTransportAgent.pm
new file mode 100644
index 0000000..51818f2
--- /dev/null
+++ b/lib/Lintian/Data/Provides/MailTransportAgent.pm
@@ -0,0 +1,193 @@
+# -*- perl -*-
+#
+# Copyright (C) 2008 Niko Tyni
+# Copyright (C) 2018 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Provides::MailTransportAgent;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(carp);
+use Const::Fast;
+use List::SomeUtils qw(first_value any);
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+const my $SLASH => q{/};
+
+const my $NEWLINE => qq{\n};
+
+=head1 NAME
+
+Lintian::Data::Provides::MailTransportAgent - Lintian interface for mail transport agents.
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Provides::MailTransportAgent;
+
+=head1 DESCRIPTION
+
+This module provides a way to load data files for mail transport agents.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item title
+
+=item location
+
+=item mail_transport_agents
+
+=item deb822_by_installable_name
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Mail Transport Agents'
+);
+
+has location => (
+    is => 'rw',
+    default => 'fields/mail-transport-agents'
+);
+
+has mail_transport_agents => (is => 'rw', default => sub { [] });
+
+=item all
+
+=cut
+
+sub all {
+    my ($self) = @_;
+
+    return keys %{$self->mail_transport_agents};
+}
+
+=item load
+
+=cut
+
+sub load {
+    my ($self, $search_space, $our_vendor) = @_;
+
+    my @candidates = map { $_ . $SLASH . $self->location } @{$search_space};
+    my $path = first_value { -e } @candidates;
+
+    unless (length $path) {
+        carp encode_utf8('Unknown data file: ' . $self->location);
+        return 0;
+    }
+
+    open(my $fd, '<:utf8_strict', $path)
+      or die encode_utf8("Cannot open $path: $!");
+
+    my $position = 1;
+    while (my $line = <$fd>) {
+
+        # trim both ends
+        $line =~ s/^\s+|\s+$//g;
+
+        next
+          unless length $line;
+
+        next
+          if $line =~ m{^ [#]}x;
+
+        my $agent = $line;
+
+        push(@{$self->mail_transport_agents}, $agent);
+
+    } continue {
+        ++$position;
+    }
+
+    close $fd;
+
+    return 1;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    my @mail_transport_agents;
+
+    # neutral sort order
+    local $ENV{LC_ALL} = 'C';
+
+    my $port = 'amd64';
+
+    my $deb822_by_installable_name
+      = $archive->deb822_packages_by_installable_name('sid', 'main', $port);
+
+    for my $installable_name (keys %{$deb822_by_installable_name}) {
+
+        my $deb822 = $deb822_by_installable_name->{$installable_name};
+
+        my @provides = $deb822->trimmed_list('Provides', qr{ \s* , \s* }x);
+
+        push(@mail_transport_agents, $installable_name)
+          if any { $_ eq 'mail-transport-agent' } @provides;
+    }
+
+    my $text = encode_utf8(<<'EOF');
+# Packages that provide mail-transport-agent
+#
+EOF
+
+    $text .= encode_utf8($_ . $NEWLINE)for sort @mail_transport_agents;
+
+    my $datapath = "$basedir/" . $self->location;
+    my $parentdir = path($datapath)->parent->stringify;
+    path($parentdir)->mkpath
+      unless -e $parentdir;
+
+    # already in UTF-8
+    path($datapath)->spew($text);
+
+    return 1;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Stylesheet.pm b/lib/Lintian/Data/Stylesheet.pm
new file mode 100644
index 0000000..bfc8c5b
--- /dev/null
+++ b/lib/Lintian/Data/Stylesheet.pm
@@ -0,0 +1,139 @@
+# -*- perl -*-
+#
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Stylesheet;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(carp);
+use Const::Fast;
+use HTTP::Tiny;
+use List::SomeUtils qw(first_value);
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+
+const my $EMPTY => q{};
+const my $SLASH => q{/};
+
+use Moo;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Data::Stylesheet - Lintian interface to CSS style sheets
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Stylesheet;
+
+=head1 DESCRIPTION
+
+This module provides a way to load data files to CSS style sheets
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item title
+
+=item location
+
+=item C<css>
+
+=cut
+
+has title => (
+    is => 'rw',
+    default => 'Lintian CSS Style Sheet'
+);
+
+has location => (
+    is => 'rw',
+    default => 'stylesheets/lintian.css'
+);
+
+has css => (is => 'rw', default => $EMPTY);
+
+=item load
+
+=cut
+
+sub load {
+    my ($self, $search_space, $our_vendor) = @_;
+
+    my @candidates = map { $_ . $SLASH . $self->location } @{$search_space};
+    my $path = first_value { -e } @candidates;
+
+    unless (length $path) {
+        carp encode_utf8('Unknown data file: ' . $self->location);
+        return 0;
+    }
+
+    my $style_sheet = path($path)->slurp_utf8;
+
+    $self->css($style_sheet);
+
+    return 1;
+}
+
+=item refresh
+
+=cut
+
+sub refresh {
+    my ($self, $archive, $basedir) = @_;
+
+    my $css_url = 'https://lintian.debian.org/stylesheets/lintian.css';
+
+    my $response = HTTP::Tiny->new->get($css_url);
+    die encode_utf8("Failed to get $css_url!\n")
+      unless $response->{success};
+
+    my $style_sheet = $response->{content};
+
+    my $data_path = "$basedir/" . $self->location;
+    my $parent_dir = path($data_path)->parent->stringify;
+    path($parent_dir)->mkpath
+      unless -e $parent_dir;
+
+    # already in UTF-8
+    path($data_path)->spew($style_sheet);
+
+    return 1;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Data/Traditional.pm b/lib/Lintian/Data/Traditional.pm
new file mode 100644
index 0000000..9deaf12
--- /dev/null
+++ b/lib/Lintian/Data/Traditional.pm
@@ -0,0 +1,73 @@
+# -*- perl -*-
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Data::Traditional;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Data::JoinedLines';
+
+=head1 NAME
+
+Lintian::Data::Traditional - Lintian interface for generic data
+
+=head1 SYNOPSIS
+
+    use Lintian::Data::Traditional;
+
+=head1 DESCRIPTION
+
+Lintian::Data::Traditional provides a way to load generic, traditional
+data files.
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item location
+
+=item separator
+
+=cut
+
+has location => (is => 'rw');
+has separator => (is => 'rw');
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Deb822.pm b/lib/Lintian/Deb822.pm
new file mode 100644
index 0000000..c153415
--- /dev/null
+++ b/lib/Lintian/Deb822.pm
@@ -0,0 +1,692 @@
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Deb822;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Path::Tiny;
+use Syntax::Keyword::Try;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Deb822::Constants qw(:constants);
+use Lintian::Deb822::Section;
+
+const my $EMPTY => q{};
+const my $NUMBER_SIGN => q{#};
+
+use Moo;
+use namespace::clean;
+
+=encoding utf-8
+
+=head1 NAME
+
+Lintian::Deb822 -- A deb822 control file
+
+=head1 SYNOPSIS
+
+ use Lintian::Deb822;
+
+=head1 DESCRIPTION
+
+Represents a paragraph in a Deb822 control file.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item sections
+
+Array of Deb822::Section objects in order of their original appearance.
+
+=item positions
+
+Line positions
+
+=cut
+
+has sections => (is => 'rw', default => sub { [] });
+has positions => (is => 'rw', default => sub { [] });
+
+=item first_mention
+
+=cut
+
+sub first_mention {
+    my ($self, $name) = @_;
+
+    my $earliest;
+
+    # empty when field not present
+    $earliest ||= $_->value($name) for @{$self->sections};
+
+    return ($earliest // $EMPTY);
+}
+
+=item last_mention
+
+=cut
+
+sub last_mention {
+    my ($self, $name) = @_;
+
+    my $latest;
+
+    for my $section (@{$self->sections}) {
+
+        # empty when field not present
+        $latest = $section->value($name)
+          if $section->declares($name);
+    }
+
+    return ($latest // $EMPTY);
+}
+
+=item read_file
+
+=cut
+
+sub read_file {
+    my ($self, $path, $flags) = @_;
+
+    my $contents = path($path)->slurp_utf8;
+
+    return $self->parse_string($contents, $flags);
+}
+
+=item parse_string
+
+=cut
+
+sub parse_string {
+    my ($self, $contents, $flags) = @_;
+
+    my (@paragraphs, @positions);
+
+    try {
+        @paragraphs= parse_dpkg_control_string($contents, $flags,\@positions);
+
+    } catch {
+        # ignore syntax errors here
+        die map { encode_utf8($_) } $@
+          unless $@ =~ /syntax error/;
+    }
+
+    my $index = 0;
+    for my $paragraph (@paragraphs) {
+
+        my $section = Lintian::Deb822::Section->new;
+        $section->verbatim($paragraph);
+        $section->positions($positions[$index]);
+
+        push(@{$self->sections}, $section);
+
+    } continue {
+        $index++;
+    }
+
+    return @{$self->sections};
+}
+
+=back
+
+=head1 FUNCTIONS
+
+=head2 Debian control parsers
+
+At first glance, this module appears to contain several debian control
+parsers.  In practise, there is only one real parser
+(L</visit_dpkg_paragraph_string>) - the rest are convenience functions around
+it.
+
+=over 4
+
+=item read_dpkg_control(FILE[, FLAGS[, LINES]])
+
+This is a convenience function to ease using L</parse_dpkg_control>
+with paths to files (rather than open handles).  The first argument
+must be the path to a FILE, which should be read as a debian control
+file.  If the file is empty, an empty list is returned.
+
+Otherwise, this behaves like:
+
+ use autodie;
+ 
+ open(my $fd, '<:encoding(UTF-8)', FILE); # or '<'
+ my @p = parse_dpkg_control($fd, FLAGS, LINES);
+ close($fd);
+ return @p;
+
+This goes without saying that may fail with any of the messages that
+L</parse_dpkg_control(HANDLE[, FLAGS[, LINES]])> do.  It can also emit
+autodie exceptions if open or close fails.
+
+=cut
+
+sub read_dpkg_control {
+    my ($file, $flags, $field_starts) = @_;
+
+    open(my $handle, '<:utf8_strict', $file)
+      or die encode_utf8("Cannot open $file");
+
+    local $/ = undef;
+    my $string = <$handle>;
+    close $handle;
+
+    my @result;
+
+    my $visitor = sub {
+        my ($paragraph, $line) = @_;
+
+        push(@result, $paragraph);
+        push(@{$field_starts}, $line) if defined $field_starts;
+    };
+
+    visit_dpkg_paragraph_string($visitor, $string, $flags);
+
+    return @result;
+}
+
+=item read_dpkg_control_lc(FILE[, FLAGS[, LINES]])
+
+=cut
+
+sub read_dpkg_control_lc {
+    my ($file, $flags, $field_starts) = @_;
+
+    my @result = read_dpkg_control($file, $flags, $field_starts);
+
+    lowercase_field_names(\@result);
+    lowercase_field_names($field_starts);
+
+    return @result;
+}
+
+=item parse_dpkg_control_string(STRING[, FLAGS[, LINES]])
+
+Reads debian control data from STRING and returns a list of
+paragraphs in it.  A paragraph is represented via a hashref, which
+maps (lower cased) field names to their values.
+
+FLAGS (if given) is a bitmask of the I<DCTRL_*> constants.  Please
+refer to L</CONSTANTS> for the list of constants and their meaning.
+The default value for FLAGS is 0.
+
+If LINES is given, it should be a reference to an empty list.  On
+return, LINES will be populated with a hashref for each paragraph (in
+the same order as the returned list).  Each hashref will also have a
+special key "I<START-OF-PARAGRAPH>" that gives the line number of the
+first field in that paragraph.  These hashrefs will map the field name
+of the given paragraph to the line number where the field name
+appeared.
+
+This is a convenience sub around L</visit_dpkg_paragraph> and can
+therefore produce the same errors as it.  Please see
+L</visit_dpkg_paragraph> for the finer semantics of how the
+control file is parsed.
+
+NB: parse_dpkg_control does I<not> close the handle for the caller.
+
+=cut
+
+sub parse_dpkg_control_string {
+    my ($string, $flags, $field_starts) = @_;
+    my @result;
+
+    my $c = sub {
+        my ($para, $line) = @_;
+
+        push(@result, $para);
+        push(@{$field_starts}, $line)
+          if defined $field_starts;
+    };
+
+    visit_dpkg_paragraph_string($c, $string, $flags);
+
+    return @result;
+}
+
+=item parse_dpkg_control_string_lc(STRING[, FLAGS[, LINES]])
+
+=cut
+
+sub parse_dpkg_control_string_lc {
+    my ($string, $flags, $field_starts) = @_;
+
+    my @result = parse_dpkg_control_string($string, $flags, $field_starts);
+
+    lowercase_field_names(\@result);
+    lowercase_field_names($field_starts);
+
+    return @result;
+}
+
+=item lowercase_field_names
+
+=cut
+
+sub lowercase_field_names {
+    my ($arrayref) = @_;
+
+    return
+      unless $arrayref;
+
+    for my $paragraph (@{$arrayref}) {
+
+        # magic marker should only appear in field starts
+        my @fields = grep { $_ ne 'START-OF-PARAGRAPH' } keys %{$paragraph};
+        my @mixedcase = grep { $_ ne lc } @fields;
+
+        for my $old (@mixedcase) {
+            $paragraph->{lc $old} = $paragraph->{$old};
+            delete $paragraph->{$old};
+        }
+    }
+
+    return;
+}
+
+=item visit_dpkg_paragraph_string (CODE, STRING[, FLAGS])
+
+Reads debian control data from STRING and passes each paragraph to
+CODE.  A paragraph is represented via a hashref, which maps (lower
+cased) field names to their values.
+
+FLAGS (if given) is a bitmask of the I<DCTRL_*> constants.  Please
+refer to L</CONSTANTS> for the list of constants and their meaning.
+The default value for FLAGS is 0.
+
+If the file is empty (i.e. it contains no paragraphs), the method will
+contain an I<empty> list.  The deb822 contents may be inside a
+I<signed> PGP message with a signature.
+
+visit_dpkg_paragraph will require the PGP headers to be correct (if
+present) and require that the entire file is covered by the signature.
+However, it will I<not> validate the signature (in fact, the contents
+of the PGP SIGNATURE part can be empty).  The signature should be
+validated separately.
+
+visit_dpkg_paragraph will pass paragraphs to CODE as they are
+completed.  If CODE can process the paragraphs as they are seen, very
+large control files can be processed without keeping all the
+paragraphs in memory.
+
+As a consequence of how the file is parsed, CODE may be passed a
+number of (valid) paragraphs before parsing is stopped due to a syntax
+error.
+
+NB: visit_dpkg_paragraph does I<not> close the handle for the caller.
+
+CODE is expected to be a callable reference (e.g. a sub) and will be
+invoked as the following:
+
+=over 4
+
+=item CODE->(PARA, LINE_NUMBERS)
+
+The first argument, PARA, is a hashref to the most recent paragraph
+parsed.  The second argument, LINE_NUMBERS, is a hashref mapping each
+of the field names to the line number where the field name appeared.
+LINE_NUMBERS will also have a special key "I<START-OF-PARAGRAPH>" that
+gives the line number of the first field in that paragraph.
+
+The return value of CODE is ignored.
+
+If the CODE invokes die (or similar) the error is propagated to the
+caller.
+
+=back
+
+
+I<On syntax errors>, visit_dpkg_paragraph will call die with the
+following string:
+
+  "syntax error at line %d: %s\n"
+
+Where %d is the line number of the issue and %s is one of:
+
+=over
+
+=item Duplicate field %s
+
+The field appeared twice in the paragraph.
+
+=item Continuation line outside a paragraph (maybe line %d should be " .")
+
+A continuation line appears outside a paragraph - usually caused by an
+unintended empty line before it.
+
+=item Whitespace line not allowed (possibly missing a ".")
+
+An empty continuation line was found.  This usually means that a
+period is missing to denote an "empty line" in (e.g.) the long
+description of a package.
+
+=item Cannot parse line "%s"
+
+Generic error containing the text of the line that confused the
+parser.  Note that all non-printables in %s will be replaced by
+underscores.
+
+=item Comments are not allowed
+
+A comment line appeared and FLAGS contained DCTRL_NO_COMMENTS.
+
+=item PGP signature seen before start of signed message
+
+A "BEGIN PGP SIGNATURE" header is seen and a "BEGIN PGP MESSAGE" has
+not been seen yet.
+
+=item Two PGP signatures (first one at line %d)
+
+Two "BEGIN PGP SIGNATURE" headers are seen in the same file.
+
+=item Unexpected %s header
+
+A valid PGP header appears (e.g. "BEGIN PUBLIC KEY BLOCK").
+
+=item Malformed PGP header
+
+An invalid or malformed PGP header appears.
+
+=item Expected at most one signed message (previous at line %d)
+
+Two "BEGIN PGP MESSAGE" headers appears in the same message.
+
+=item End of file but expected an "END PGP SIGNATURE" header
+
+The file ended after a "BEGIN PGP SIGNATURE" header without being
+followed by an "END PGP SIGNATURE".
+
+=item PGP MESSAGE header must be first content if present
+
+The file had content before PGP MESSAGE.
+
+=item Data after the PGP SIGNATURE
+
+The file had data after the PGP SIGNATURE block ended.
+
+=item End of file before "BEGIN PGP SIGNATURE"
+
+The file had a "BEGIN PGP MESSAGE" header, but no signature was
+present.
+
+=back
+
+=cut
+
+sub visit_dpkg_paragraph_string {
+    my ($code, $string, $flags) = @_;
+    $flags//=0;
+    my $field_starts = {};
+    my $section = {};
+    my $open_section = 0;
+    my $last_tag;
+    my $debconf = $flags & DCTRL_DEBCONF_TEMPLATE;
+    my $signed = 0;
+    my $signature = 0;
+
+    my @lines = split(/\n/, $string);
+
+    my $position = 1;
+
+    my $line;
+    while (defined($line = shift @lines)) {
+        chomp $line;
+
+        if (substr($line, 0, 1) eq $NUMBER_SIGN) {
+            next
+              unless $flags & DCTRL_NO_COMMENTS;
+            die encode_utf8("No comments allowed (line $position).\n");
+        }
+
+        # empty line?
+        if ($line eq $EMPTY || (!$debconf && $line =~ /^\s*$/)) {
+            if ($open_section) { # end of current section
+                 # pass the current section to the handler
+                $code->($section, $field_starts);
+                $section = {};
+                $field_starts = {};
+                $open_section = 0;
+            }
+        }
+        # pgp sig? Be strict here (due to #696230)
+        # According to http://tools.ietf.org/html/rfc4880#section-6.2
+        # The header MUST start at the beginning of the line and MUST NOT have
+        # any other text (except whitespace) after the header.
+        elsif ($line =~ m/^-----BEGIN PGP SIGNATURE-----[ \r\t]*$/)
+        { # skip until end of signature
+            my $saw_end = 0;
+
+            die encode_utf8("PGP signature before message (line $position).\n")
+              unless $signed;
+
+            die encode_utf8(
+"Found two PGP signatures (line $signature and line $position).\n"
+            )if $signature;
+
+            $signature = $position;
+            while (defined($line = shift @lines)) {
+                if ($line =~ /^-----END PGP SIGNATURE-----[ \r\t]*$/) {
+                    $saw_end = 1;
+                    last;
+                }
+            }continue {
+                ++$position;
+            }
+
+            # The "at line X" may seem a little weird, but it keeps the
+            # message format identical.
+            die encode_utf8("Cannot find END PGP SIGNATURE header.\n")
+              unless $saw_end;
+        }
+        # other pgp control?
+        elsif ($line =~ /^-----(?:BEGIN|END) PGP/) {
+            # At this point it could be a malformed PGP header or one
+            # of the following valid headers (RFC4880):
+            #  * BEGIN PGP MESSAGE
+            #    - Possibly a signed Debian CTRL, so okay (for now)
+            #  * BEGIN PGP {PUBLIC,PRIVATE} KEY BLOCK
+            #    - Valid header, but not a Debian CTRL file.
+            #  * BEGIN PGP MESSAGE, PART X{,/Y}
+            #    - Valid, but we don't support partial messages, so
+            #      bail on those.
+
+            unless ($line =~ /^-----BEGIN PGP SIGNED MESSAGE-----[ \r\t]*$/) {
+                # Not a (full) PGP MESSAGE; reject.
+
+                my $key = qr/(?:BEGIN|END) PGP (?:PUBLIC|PRIVATE) KEY BLOCK/;
+                my $msgpart = qr{BEGIN PGP MESSAGE, PART \d+(?:/\d+)?};
+                my $msg
+                  = qr/(?:BEGIN|END) PGP (?:(?:COMPRESSED|ENCRYPTED) )?MESSAGE/;
+
+                if ($line =~ /^-----($key|$msgpart|$msg)-----[ \r\t]*$/) {
+                    die encode_utf8(
+                        "Unexpected $1 header (line $position).\n");
+                }
+
+                die encode_utf8("Malformed PGP header (line $position).\n");
+
+            } else {
+                die encode_utf8(
+"Multiple PGP messages (line $signed and line $position).\n"
+                )if $signed;
+
+                # NB: If you remove this, keep in mind that it may
+                # allow two paragraphs to merge.  Consider:
+                #
+                # Field-P1: some-value
+                # -----BEGIN PGP SIGNATURE-----
+                #
+                # Field-P2: another value
+                #
+                # At the time of writing: If $open_section is
+                # true, it will remain so until the empty line
+                # after the PGP header.
+                die encode_utf8(
+                    "Expected PGP MESSAGE header (line $position).\n")
+                  if $last_tag;
+
+                $signed = $position;
+            }
+
+            # skip until the next blank line
+            while (defined($line = shift @lines)) {
+                last
+                  if $line =~ /^\s*$/;
+            }continue {
+                ++$position;
+            }
+        }
+       # did we see a signature already?  We allow all whitespace/comment lines
+       # outside the signature.
+        elsif ($signature) {
+            # Accept empty lines after the signature.
+            next
+              if $line =~ /^\s*$/;
+
+            # NB: If you remove this, keep in mind that it may allow
+            # two paragraphs to merge.  Consider:
+            #
+            # Field-P1: some-value
+            # -----BEGIN PGP SIGNATURE-----
+            # [...]
+            # -----END PGP SIGNATURE-----
+            # Field-P2: another value
+            #
+            # At the time of writing: If $open_section is true, it
+            # will remain so until the empty line after the PGP
+            # header.
+            die encode_utf8("Data after PGP SIGNATURE (line $position).\n");
+        }
+        # new empty field?
+        elsif ($line =~ /^([^: \t]+):\s*$/) {
+            $field_starts->{'START-OF-PARAGRAPH'} = $position
+              unless $open_section;
+            $open_section = 1;
+
+            my $tag = $1;
+            $section->{$tag} = $EMPTY;
+            $field_starts->{$tag} = $position;
+
+            $last_tag = $tag;
+        }
+        # new field?
+        elsif ($line =~ /^([^: \t]+):\s*(.*)$/) {
+            $field_starts->{'START-OF-PARAGRAPH'} = $position
+              unless $open_section;
+            $open_section = 1;
+
+            # Policy: Horizontal whitespace (spaces and tabs) may occur
+            # immediately before or after the value and is ignored there.
+            my $tag = $1;
+            my $value = $2;
+
+            # trim right
+            $value =~ s/\s+$//;
+
+            if (exists $section->{$tag}) {
+                # Policy: A paragraph must not contain more than one instance
+                # of a particular field name.
+                die encode_utf8("Duplicate field $tag (line $position).\n");
+            }
+            $value =~ s/#.*$//
+              if $flags & DCTRL_COMMENTS_AT_EOL;
+            $section->{$tag} = $value;
+            $field_starts->{$tag} = $position;
+
+            $last_tag = $tag;
+        }
+
+        # continued field?
+        elsif ($line =~ /^([ \t].*\S.*)$/) {
+            die encode_utf8(
+"Continuation line not in paragraph (line $position). Missing a dot on the previous line?\n"
+            )unless $open_section;
+
+            # Policy: Many fields' values may span several lines; in this case
+            # each continuation line must start with a space or a tab.  Any
+            # trailing spaces or tabs at the end of individual lines of a
+            # field value are ignored.
+            my $value = $1;
+
+            # trim right
+            $value =~ s/\s+$//;
+
+            $value =~ s/#.*$//
+              if $flags & DCTRL_COMMENTS_AT_EOL;
+            $section->{$last_tag} .= "\n" . $value;
+        }
+        # None of the above => syntax error
+        else {
+
+            die encode_utf8(
+                "Unexpected whitespace (line $position). Missing a dot?\n")
+              if $line =~ /^\s+$/;
+
+            # Replace non-printables and non-space characters with
+            # "_" - just in case.
+            $line =~ s/[^[:graph:][:space:]]/_/g;
+
+            die encode_utf8("Cannot parse line $position: $line\n");
+        }
+
+    }continue {
+        ++$position;
+    }
+
+    # pass the last section (if not already done).
+    $code->($section, $field_starts)
+      if $open_section;
+
+    # Given the API, we cannot use this check to prevent any
+    # paragraphs from being emitted to the code argument, so we might
+    # as well just do this last.
+
+    die encode_utf8("Cannot find BEGIN PGP SIGNATURE\n.")
+      if $signed && !$signature;
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written Christian Schwarz and many other people.
+
+Moo version by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Deb822/Constants.pm b/lib/Lintian/Deb822/Constants.pm
new file mode 100644
index 0000000..a30e117
--- /dev/null
+++ b/lib/Lintian/Deb822/Constants.pm
@@ -0,0 +1,87 @@
+# Hey emacs! This is a -*- Perl -*- script!
+# Lintian::Deb822::Constants -- Perl utility functions for parsing deb822 files
+
+# Copyright (C) 1998 Christian Schwarz
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Deb822::Constants;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use constant {
+    DCTRL_DEBCONF_TEMPLATE => 1,
+    DCTRL_NO_COMMENTS => 2,
+    DCTRL_COMMENTS_AT_EOL => 4,
+};
+
+our %EXPORT_TAGS = (constants =>
+      [qw(DCTRL_DEBCONF_TEMPLATE DCTRL_NO_COMMENTS DCTRL_COMMENTS_AT_EOL)],);
+
+our @EXPORT_OK = (@{ $EXPORT_TAGS{constants} });
+
+use Exporter qw(import);
+
+=head1 NAME
+
+Lintian::Deb822::Constants - Lintian's generic Deb822 constants
+
+=head1 SYNOPSIS
+
+ use Lintian::Deb822::Constants qw(DCTRL_NO_COMMENTS);
+
+=head1 DESCRIPTION
+
+This module contains a number of utility subs that are nice to have,
+but on their own did not warrant their own module.
+
+Most subs are imported only on request.
+
+=head1 CONSTANTS
+
+The following constants can be passed to the Debian control file
+parser functions to alter their parsing flag.
+
+=over 4
+
+=item DCTRL_DEBCONF_TEMPLATE
+
+The file should be parsed as debconf template.  These have slightly
+syntax rules for whitespace in some cases.
+
+=item DCTRL_NO_COMMENTS
+
+The file do not allow comments.  With this flag, any comment in the
+file is considered a syntax error.
+
+=back
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Deb822/Section.pm b/lib/Lintian/Deb822/Section.pm
new file mode 100644
index 0000000..5950ee4
--- /dev/null
+++ b/lib/Lintian/Deb822/Section.pm
@@ -0,0 +1,373 @@
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Deb822::Section;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::Compare;
+
+const my $EMPTY => q{};
+
+const my $UNKNOWN_POSITION => -1;
+
+use Moo;
+use namespace::clean;
+
+=encoding utf-8
+
+=head1 NAME
+
+Lintian::Deb822::Section -- A paragraph in a control file
+
+=head1 SYNOPSIS
+
+ use Lintian::Deb822::Section;
+
+=head1 DESCRIPTION
+
+Represents a paragraph in a Deb822 control file.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item legend
+
+Returns exact field names for their lowercase versions.
+
+=item verbatim
+
+Returns a hash to the raw, unedited and verbatim field values.
+
+=item unfolded
+
+Returns a hash to unfolded field values. Continuations lines
+have been connected.
+
+=item positions
+
+The original line positions.
+
+=cut
+
+has legend => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my %legend;
+
+        for my $key (keys %{$self->verbatim}) {
+
+            my $lowercase = lc $key;
+            $legend{$lowercase} = $key;
+        }
+
+        return \%legend;
+    }
+);
+
+has verbatim => (is => 'rw', default => sub { {} });
+has unfolded => (is => 'rw', default => sub { {} });
+has positions => (is => 'rw', default => sub { {} });
+
+=item trimmed_list(FIELD [, SEPARATOR])
+
+=cut
+
+sub trimmed_list {
+    my ($self, $name, $regex) = @_;
+
+    $regex //= qr/\s+/;
+
+    my $value = $self->value($name);
+
+    # trim both ends
+    $value =~ s/^\s+|\s+$//g;
+
+    my @list = split($regex, $value);
+
+    # trim both ends of each element
+    s/^\s+|\s+$//g for @list;
+
+    return grep { length } @list;
+}
+
+=item unfolded_value (FIELD)
+
+This method returns the unfolded value of the control field FIELD in
+the control file for the package.  For a source package, this is the
+*.dsc file; for a binary package, this is the control file in the
+control section of the package.
+
+If FIELD is passed but not present, then this method returns undef.
+
+=cut
+
+sub unfolded_value {
+    my ($self, $name) = @_;
+
+    return $EMPTY
+      unless length $name;
+
+    my $lowercase = lc $name;
+
+    my $unfolded = $self->unfolded->{$lowercase};
+    return $unfolded
+      if defined $unfolded;
+
+    my $value = $self->value($name);
+
+    # will also replace a newline at the very end
+    $value =~ s/\n//g;
+
+    # Remove leading space as it confuses some of the other checks
+    # that are anchored.  This happens if the field starts with a
+    # space and a newline, i.e ($ marks line end):
+    #
+    # Vcs-Browser: $
+    #  http://somewhere.com/$
+    $value =~ s/^\s*+//;
+
+    $self->unfolded->{$lowercase} = $value;
+
+    return $value;
+}
+
+=item value (FIELD)
+
+If FIELD is given, this method returns the value of the control field
+FIELD.
+
+=cut
+
+sub value {
+    my ($self, $name) = @_;
+
+    return $EMPTY
+      unless length $name;
+
+    my $exact = $self->legend->{lc $name};
+    return $EMPTY
+      unless length $exact;
+
+    my $trimmed = $self->verbatim->{$exact} // $EMPTY;
+
+    # trim both ends
+    $trimmed =~ s/^\s+|\s+$//g;
+
+    return $trimmed;
+}
+
+=item untrimmed_value (FIELD)
+
+If FIELD is given, this method returns the value of the control field
+FIELD.
+
+=cut
+
+sub untrimmed_value {
+    my ($self, $name) = @_;
+
+    return $EMPTY
+      unless length $name;
+
+    my $exact = $self->legend->{lc $name};
+    return $EMPTY
+      unless length $exact;
+
+    return $self->verbatim->{$exact} // $EMPTY;
+}
+
+=item text (FIELD)
+
+=cut
+
+sub text {
+    my ($self, $name) = @_;
+
+    my $text = $self->untrimmed_value($name);
+
+    # remove leading space in each line
+    $text =~ s/^[ \t]//mg;
+
+    # remove dot place holder for empty lines
+    $text =~ s/^\.$//mg;
+
+    return $text;
+}
+
+=item store (FIELD, VALUE)
+
+=cut
+
+sub store {
+    my ($self, $name, $value) = @_;
+
+    $value //= $EMPTY;
+
+    return
+      unless length $name;
+
+    my $exact = $self->legend->{lc $name};
+
+    # add new value if key not found
+    unless (defined $exact) {
+
+        $exact = $name;
+
+        # update legend with exact spelling
+        $self->legend->{lc $exact} = $exact;
+
+        # remove any old position
+        $self->positions->{$exact} = $UNKNOWN_POSITION;
+    }
+
+    $self->verbatim->{$exact} = $value;
+
+    # remove old unfolded value, if any
+    delete $self->unfolded->{$exact};
+
+    return;
+}
+
+=item drop (FIELD)
+
+=cut
+
+sub drop {
+    my ($self, $name) = @_;
+
+    return
+      unless length $name;
+
+    my $exact = $self->legend->{lc $name};
+    return
+      unless length $exact;
+
+    delete $self->legend->{lc $exact};
+
+    delete $self->verbatim->{$exact};
+    delete $self->unfolded->{$exact};
+    delete $self->positions->{$exact};
+
+    return;
+}
+
+=item declares (NAME)
+
+Returns a boolean for whether the named field exists.
+
+=cut
+
+sub declares {
+    my ($self, $name) = @_;
+
+    return 1
+      if defined $self->legend->{lc $name};
+
+    return 0;
+}
+
+=item names
+
+Returns an array with the literal field names.
+
+=cut
+
+sub names {
+    my ($self) = @_;
+
+    return keys %{$self->verbatim};
+}
+
+=item literal_name
+
+Returns an array with the literal, true case field names.
+
+=cut
+
+sub literal_name {
+    my ($self, $anycase) = @_;
+
+    return $self->legend->{ lc $anycase };
+}
+
+=item position
+
+With an argument, returns the starting line of the named field.
+
+Without an argument, return the starting line of the paragraph.
+
+=cut
+
+sub position {
+    my ($self, $field) = @_;
+
+    return $self->positions->{'START-OF-PARAGRAPH'}
+      unless length $field;
+
+    my $exact = $self->legend->{lc $field};
+    return undef
+      unless length $exact;
+
+    return $self->positions->{$exact};
+}
+
+=item extra
+
+=cut
+
+sub extra {
+    my ($self, @reference) = @_;
+
+    my @lowercase = map { lc } @reference;
+
+    my $extra_lc
+      = List::Compare->new([keys %{$self->legend}], \@lowercase);
+    my @extra_lowercase = $extra_lc->get_Lonly;
+
+    my @extra = map { $self->literal_name($_) } @extra_lowercase;
+
+    return @extra;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Debian/Control.pm b/lib/Lintian/Debian/Control.pm
new file mode 100644
index 0000000..cd99302
--- /dev/null
+++ b/lib/Lintian/Debian/Control.pm
@@ -0,0 +1,198 @@
+# -*- perl -*-
+# Lintian::Debian::Control -- object for fields in d/control
+
+# Copyright (C) 2008 Russ Allbery
+# Copyright (C) 2009 Raphael Geissert
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Debian::Control;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Path::Tiny;
+use Syntax::Keyword::Try;
+use Unicode::UTF8 qw(valid_utf8 decode_utf8 encode_utf8);
+
+use Lintian::Deb822;
+use Lintian::Deb822::Section;
+use Lintian::Util qw($PKGNAME_REGEX);
+
+use Moo;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Debian::Control - Lintian interface to d/control fields
+
+=head1 SYNOPSIS
+
+    use Lintian::Debian::Control;
+
+=head1 DESCRIPTION
+
+Lintian::Debian::Control provides access to fields in d/control.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item item
+=item source_fields
+=item installable_fields_by_name
+
+=cut
+
+has item => (is => 'rw');
+
+has source_fields => (
+    is => 'rw',
+    default => sub { return Lintian::Deb822::Section->new; },
+    coerce => sub {
+        my ($blessedref) = @_;
+        return ($blessedref // Lintian::Deb822::Section->new);
+    },
+);
+
+has installable_fields_by_name => (
+    is => 'rw',
+    default => sub { {} },
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+);
+
+=item load
+
+=cut
+
+sub load {
+    my ($self, $item) = @_;
+
+    return
+      unless defined $item;
+
+    $self->item($item);
+
+    return
+      unless -r $item->unpacked_path;
+
+    my $deb822 = Lintian::Deb822->new;
+
+    my @sections;
+    try {
+        @sections = $deb822->read_file($item->unpacked_path);
+
+    } catch {
+        # If it is a syntax error, ignore it (we emit
+        # syntax-error-in-control-file in this case via
+        # control-file).
+        die map { encode_utf8($_) } $@
+          unless $@ =~ /syntax error/;
+
+        return;
+    }
+
+    # in theory, one could craft a package in which d/control is empty
+    my $source = shift @sections;
+    $self->source_fields($source);
+
+    my @named
+      = grep { $_->value('Package') =~ m{\A $PKGNAME_REGEX \Z}x }@sections;
+
+    my %by_name = map { $_->value('Package') => $_ } @named;
+
+    $self->installable_fields_by_name(\%by_name);
+
+    return;
+}
+
+=item installables
+
+Returns a list of the binary and udeb packages listed in the
+F<debian/control>.
+
+=cut
+
+sub installables {
+    my ($self) = @_;
+
+    return keys %{$self->installable_fields_by_name};
+}
+
+=item installable_package_type (NAME)
+
+Returns package type based on value of the Package-Type (or if absent,
+X-Package-Type) field.  If the field is omitted, the default value
+"deb" is used.
+
+If NAME is not an installable listed in the source packages
+F<debian/control> file, this method return C<undef>.
+
+=cut
+
+sub installable_package_type {
+    my ($self, $name) = @_;
+
+    my $type;
+
+    my $fields = $self->installable_fields_by_name->{$name};
+
+    $type = $fields->value('Package-Type') || $fields->value('XC-Package-Type')
+      if defined $fields;
+
+    $type ||= 'deb';
+
+    return lc $type;
+}
+
+=item installable_fields (PACKAGE)
+
+Returns the Deb822::Section object for the installable. Returns an
+empty object if the installable does not exist.
+
+=cut
+
+sub installable_fields {
+    my ($self, $package) = @_;
+
+    my $per_package;
+
+    $per_package = $self->installable_fields_by_name->{$package}
+      if length $package;
+
+    return ($per_package // Lintian::Deb822::Section->new);
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Russ Allbery <rra@debian.org> for Lintian.
+Amended by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Elf/Section.pm b/lib/Lintian/Elf/Section.pm
new file mode 100644
index 0000000..f5ff7af
--- /dev/null
+++ b/lib/Lintian/Elf/Section.pm
@@ -0,0 +1,156 @@
+# Copyright (C) 2021 Felix Lechner <felix.lechner@lease-up.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Elf::Section;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $EMPTY => q{};
+
+use Moo;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Elf::Section -- ELF Sections
+
+=head1 SYNOPSIS
+
+ use Lintian::Elf::Section;
+
+=head1 DESCRIPTION
+
+A class for storing ELF section data
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item number
+
+=item name
+
+=item type
+
+=item address
+
+=item offset
+
+=item size
+
+=item entry_size
+
+=item flags
+
+=item index_link
+
+=item index_info
+
+=item alignment
+
+=cut
+
+has number => (
+    is => 'rw',
+    coerce => sub { my ($number) = @_; return ($number // 0); },
+    default => 0
+);
+
+has name => (
+    is => 'rw',
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); },
+    default => $EMPTY
+);
+
+has type => (
+    is => 'rw',
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); },
+    default => $EMPTY
+);
+
+has address => (
+    is => 'rw',
+    coerce => sub { my ($number) = @_; return ($number // 0); },
+    default => 0
+);
+
+has offset => (
+    is => 'rw',
+    coerce => sub { my ($number) = @_; return ($number // 0); },
+    default => 0
+);
+
+has size => (
+    is => 'rw',
+    coerce => sub { my ($number) = @_; return ($number // 0); },
+    default => 0
+);
+
+has entry_size => (
+    is => 'rw',
+    coerce => sub { my ($number) = @_; return ($number // 0); },
+    default => 0
+);
+
+has flags => (
+    is => 'rw',
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); },
+    default => $EMPTY
+);
+
+has index_link => (
+    is => 'rw',
+    coerce => sub { my ($number) = @_; return ($number // 0); },
+    default => 0
+);
+
+has index_info => (
+    is => 'rw',
+    coerce => sub { my ($number) = @_; return ($number // 0); },
+    default => 0
+);
+
+has alignment => (
+    is => 'rw',
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); },
+    default => $EMPTY
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Elf/Symbol.pm b/lib/Lintian/Elf/Symbol.pm
new file mode 100644
index 0000000..ae20dd0
--- /dev/null
+++ b/lib/Lintian/Elf/Symbol.pm
@@ -0,0 +1,90 @@
+# Copyright (C) 2021 Felix Lechner <felix.lechner@lease-up.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Elf::Symbol;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $EMPTY => q{};
+
+use Moo;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Elf::Symbol -- ELF Symbols
+
+=head1 SYNOPSIS
+
+ use Lintian::Elf::Symbol;
+
+=head1 DESCRIPTION
+
+A class for storing ELF symbol data
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item name
+
+=item version
+
+=item section
+
+=cut
+
+has name => (
+    is => 'rw',
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); },
+    default => $EMPTY
+);
+has version => (
+    is => 'rw',
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); },
+    default => $EMPTY
+);
+has section => (
+    is => 'rw',
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); },
+    default => $EMPTY
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Group.pm b/lib/Lintian/Group.pm
new file mode 100644
index 0000000..010f42e
--- /dev/null
+++ b/lib/Lintian/Group.pm
@@ -0,0 +1,794 @@
+# Copyright (C) 2011 Niels Thykier <niels@thykier.net>
+# Copyright (C) 2019-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Group;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use Cwd;
+use Devel::Size qw(total_size);
+use Email::Address::XS;
+use File::Spec;
+use List::Compare;
+use List::SomeUtils qw(any none uniq firstval true);
+use List::UtilsBy qw(sort_by);
+use POSIX qw(ENOENT);
+use Syntax::Keyword::Try;
+use Time::HiRes qw(gettimeofday tv_interval);
+use Time::Piece;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Hint::Pointed;
+use Lintian::Mask;
+use Lintian::Util qw(human_bytes match_glob);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $UNDERSCORE => q{_};
+
+const my $EXTRA_VERBOSE => 3;
+
+# A private table of supported types.
+const my %SUPPORTED_TYPES => (
+    'binary'  => 1,
+    'buildinfo' => 1,
+    'changes' => 1,
+    'source'  => 1,
+    'udeb'    => 1,
+);
+
+use Moo;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Group -- A group of objects that Lintian can process
+
+=head1 SYNOPSIS
+
+ use Lintian::Group;
+
+ my $group = Lintian::Group->new('lintian_2.5.0_i386.changes');
+
+=head1 DESCRIPTION
+
+Instances of this perl class are sets of
+L<processables|Lintian::Processable>.  It allows at most one source
+and one changes or buildinfo package per set, but multiple binary packages
+(provided that the binary is not already in the set).
+
+=head1 METHODS
+
+=over 4
+
+=item $group->pooldir
+
+Returns or sets the pool directory used by this group.
+
+=item $group->source_name
+
+=item $group->source_version
+
+=item $group->binary
+
+Returns a hash reference to the binary processables in this group.
+
+=item $group->buildinfo
+
+Returns the buildinfo processable in this group.
+
+=item $group->changes
+
+Returns the changes processable in this group.
+
+=item $group->source
+
+Returns the source processable in this group.
+
+=item $group->udeb
+
+Returns a hash reference to the udeb processables in this group.
+
+=item jobs
+
+Returns or sets the max number of jobs to be processed in parallel.
+
+If the limit is 0, then there is no limit for the number of parallel
+jobs.
+
+=item processing_start
+
+=item processing_end
+
+=item cache
+
+Cache for some items.
+
+=item profile
+
+Hash with active jobs.
+
+=item C<saved_direct_dependencies>
+
+=item C<saved_direct_reliants>
+
+=cut
+
+has pooldir => (is => 'rw', default => $EMPTY);
+has source_name => (is => 'rw', default => $EMPTY);
+has source_version => (is => 'rw', default => $EMPTY);
+
+has binary => (is => 'rw', default => sub{ {} });
+has buildinfo => (is => 'rw');
+has changes => (is => 'rw');
+has source => (is => 'rw');
+has udeb => (is => 'rw', default => sub{ {} });
+
+has jobs => (is => 'rw', default => 1);
+has processing_start => (is => 'rw', default => $EMPTY);
+has processing_end => (is => 'rw', default => $EMPTY);
+
+has cache => (is => 'rw', default => sub { {} });
+has profile => (is => 'rw', default => sub { {} });
+
+=item $group->name
+
+Returns a unique identifier for the group based on source and version.
+
+=cut
+
+sub name {
+    my ($self) = @_;
+
+    return $EMPTY
+      unless length $self->source_name && length $self->source_version;
+
+    return $self->source_name . $UNDERSCORE . $self->source_version;
+}
+
+=item process
+
+Process group.
+
+=cut
+
+sub process {
+    my ($self, $ignored_overrides, $option)= @_;
+
+    my $groupname = $self->name;
+    local $SIG{__WARN__}
+      = sub { warn encode_utf8("Warning in group $groupname: $_[0]") };
+
+    my $savedir = getcwd;
+
+    $self->processing_start(gmtime->datetime . 'Z');
+    say {*STDERR} encode_utf8('Starting on group ' . $self->name)
+      if $option->{debug};
+    my $group_timer = [gettimeofday];
+
+    my $success = 1;
+    for my $processable ($self->get_processables){
+
+        my $path = $processable->path;
+        local $SIG{__WARN__}
+          = sub { warn encode_utf8("Warning in processable $path: $_[0]") };
+
+        my @hints;
+        my %enabled_overrides;
+
+        say {*STDERR}
+          encode_utf8(
+            'Base directory for processable: '. $processable->basedir)
+          if $option->{debug};
+
+        unless ($option->{'no-override'}) {
+
+            say {*STDERR} encode_utf8('Loading overrides file (if any) ...')
+              if $option->{debug};
+
+            for my $override (@{$processable->overrides}) {
+
+                my $pattern = $override->pattern;
+
+                # catch renames
+                my $tag_name
+                  = $self->profile->get_current_name($override->tag_name);
+
+                # catches unknown tags
+                next
+                  unless length $tag_name;
+
+                next
+                  unless $self->profile->tag_is_enabled($tag_name);
+
+                my @architectures = @{$override->architectures};
+
+                # count negations
+                my $negations = true { /^!/ } @architectures;
+
+                # strip negations if present
+                s/^!// for @architectures;
+
+                # enable overrides for this architecture
+                # proceed when none specified
+                my $data = $self->profile->data;
+                next
+                  if @architectures
+                  && (
+                    $negations xor none {
+                        $data->architectures->restriction_matches($_,
+                            $processable->architecture)
+                    }@architectures
+                  );
+
+                if ($self->profile->is_durable($tag_name)) {
+
+                    ++$ignored_overrides->{$tag_name};
+                    next;
+                }
+
+                $enabled_overrides{$tag_name}{$pattern} = $override;
+            }
+        }
+
+        my @check_names = sort $self->profile->enabled_checks;
+
+        my @from_checks;
+        for my $name (@check_names) {
+
+            my $absolute = $self->profile->check_path_by_name->{$name};
+            require $absolute;
+
+            my $module = $self->profile->check_module_by_name->{$name};
+            my $check = $module->new;
+
+            $check->name($name);
+            $check->processable($processable);
+            $check->group($self);
+            $check->profile($self->profile);
+
+            my $timer = [gettimeofday];
+            my $procid = $processable->identifier;
+            say {*STDERR} encode_utf8("Running check: $name on $procid  ...")
+              if $option->{debug};
+
+            try {
+                my @found_here = $check->run;
+                push(@from_checks, @found_here);
+
+            } catch {
+                my $message = $@;
+                $message
+                  .= "warning: cannot run $name check on package $procid\n";
+                $message .= "skipping check of $procid\n";
+                warn encode_utf8($message);
+
+                $success = 0;
+
+                next;
+            }
+
+            my $raw_res = tv_interval($timer);
+            my $tres = sprintf('%.3fs', $raw_res);
+
+            say {*STDERR} encode_utf8("Check $name for $procid done ($tres)")
+              if $option->{debug};
+            say {*STDERR} encode_utf8("$procid,check/$name,$raw_res")
+              if $option->{'perf-output'};
+        }
+
+        my %context_tracker;
+        my %used_overrides;
+
+        for my $hint (@from_checks) {
+
+            my $as_issued = $hint->tag_name;
+
+            croak encode_utf8('No tag name')
+              unless length $as_issued;
+
+            my $issuer = $hint->issued_by;
+
+            # try local name space
+            my $tag = $self->profile->get_tag("$issuer/$as_issued");
+
+            warn encode_utf8(
+"Using tag $as_issued as name spaced while not so declared (in check $issuer)."
+            )if defined $tag && !$tag->name_spaced;
+
+            # try global name space
+            $tag ||= $self->profile->get_tag($as_issued);
+
+            unless (defined $tag) {
+                warn encode_utf8(
+                    "Tried to issue unknown tag $as_issued in check $issuer.");
+                next;
+            }
+
+            if (  !$tag->name_spaced && $tag->name ne $as_issued
+                || $tag->name_spaced && $tag->name ne "$issuer/$as_issued") {
+
+                my $current_name = $tag->name;
+                warn encode_utf8(
+"Tried to issue renamed tag $as_issued (current name $current_name) in check $issuer."
+                );
+
+                next;
+            }
+
+            my $owner = $tag->check;
+            if ($issuer ne $owner) {
+                warn encode_utf8(
+                    "Check $issuer has no tag $as_issued (but $owner does).");
+                next;
+            }
+
+            # pull name from tag; could be name-spaced
+            $hint->tag_name($tag->name);
+            my $tag_name = $hint->tag_name;
+
+            # skip disabled tags
+            next
+              unless $self->profile->tag_is_enabled($tag_name);
+
+            my $context = $hint->context;
+
+            if (exists $context_tracker{$tag_name}{$context}) {
+                warn encode_utf8(
+"Tried to issue duplicate hint in check $issuer: $tag_name $context\n"
+                );
+                next;
+            }
+
+            $context_tracker{$tag_name}{$context} = 1;
+
+            my @masks;
+            for my $screen (@{$tag->screens}) {
+
+                next
+                  unless $screen->suppress($processable, $hint);
+
+                my $mask = Lintian::Mask->new;
+                $mask->screen($screen->name);
+
+                push(@masks, $mask);
+            }
+
+            my @screen_names = map { $_->screen } @masks;
+            my $screen_list = join($SPACE, (sort @screen_names));
+
+            warn encode_utf8("Crossing screens for $tag_name ($screen_list)")
+              if @masks > 1;
+
+            $hint->masks(\@masks)
+              if !$tag->show_always;
+
+            if (exists $enabled_overrides{$tag_name}) {
+
+                my $for_tag = $enabled_overrides{$tag_name};
+
+                if (exists $for_tag->{$EMPTY}) {
+                    $hint->override($for_tag->{$EMPTY});
+
+                } else {
+
+                    # overrides without context handled above
+                    my @patterns = grep { length } keys %{$for_tag};
+
+                    # try short ones first
+                    my @by_length = sort_by { length } @patterns;
+
+                    my $match = firstval {
+                        match_glob($_, $hint->context)
+                    }
+                    @by_length;
+
+                    $hint->override($for_tag->{$match})
+                      if defined $match;
+                }
+            }
+
+            # new hash values autovivify to 0
+            ++$used_overrides{$tag_name}{$hint->override->pattern}
+              if defined $hint->override;
+
+            push(@hints, $hint);
+        }
+
+        # look for unused overrides
+        for my $tag_name (keys %enabled_overrides) {
+
+            my @declared_patterns = keys %{$enabled_overrides{$tag_name}};
+            my @used_patterns = keys %{$used_overrides{$tag_name} // {}};
+
+            my $pattern_lc
+              = List::Compare->new(\@declared_patterns, \@used_patterns);
+            my @unused_patterns = $pattern_lc->get_Lonly;
+
+            for my $pattern (@unused_patterns) {
+
+                my $override = $enabled_overrides{$tag_name}{$pattern};
+
+                my $override_item = $processable->override_file;
+                my $position = $override->position;
+                my $pointer = $override_item->pointer($position);
+
+                my $unused = Lintian::Hint::Pointed->new;
+                $unused->issued_by('lintian');
+
+                $unused->tag_name('unused-override');
+                $unused->tag_name('mismatched-override')
+                  if exists $context_tracker{$tag_name};
+
+                # use the original name, in case the tag was renamed
+                my $original_name = $override->tag_name;
+                $unused->note($original_name . $SPACE . $pattern);
+
+                $unused->pointer($pointer);
+
+                # cannot be overridden or suppressed
+                push(@hints, $unused);
+            }
+        }
+
+        # carry hints into the output modules
+        $processable->hints(\@hints);
+    }
+
+    $self->processing_end(gmtime->datetime . 'Z');
+
+    my $raw_res = tv_interval($group_timer);
+    my $tres = sprintf('%.3fs', $raw_res);
+    say {*STDERR}
+      encode_utf8('Checking all of group ' . $self->name . " done ($tres)")
+      if $option->{debug};
+    say {*STDERR} encode_utf8($self->name . ",total-group-check,$raw_res")
+      if $option->{'perf-output'};
+
+    if ($option->{'debug'} > 2) {
+
+        # suppress warnings without reliable sizes
+        local $Devel::Size::warn = 0;
+
+        my @processables = $self->get_processables;
+        my $pivot = shift @processables;
+        my $group_id
+          = $pivot->source_name . $UNDERSCORE . $pivot->source_version;
+        my $group_usage
+          = human_bytes(total_size([map { $_ } $self->get_processables]));
+        say {*STDERR}
+          encode_utf8("Memory usage [group:$group_id]: $group_usage")
+          if $option->{debug} >= $EXTRA_VERBOSE;
+
+        for my $processable ($self->get_processables) {
+            my $id = $processable->identifier;
+            my $usage = human_bytes(total_size($processable));
+
+            say {*STDERR} encode_utf8("Memory usage [$id]: $usage")
+              if $option->{debug} >= $EXTRA_VERBOSE;
+        }
+    }
+
+    # change to known folder; ealier failures could prevent removal below
+    chdir $savedir
+      or warn encode_utf8("Cannot change to directory $savedir");
+
+    return $success;
+}
+
+=item $group->add_processable($proc)
+
+Adds $proc to $group.  At most one source and one changes $proc can be
+in a $group.  There can be multiple binary $proc's, as long as they
+are all unique.  Successive buildinfo $proc's are silently ignored.
+
+This will error out if an additional source or changes $proc is added
+to the group. Otherwise it will return a truth value if $proc was
+added.
+
+=cut
+
+sub add_processable {
+    my ($self, $processable) = @_;
+
+    if ($processable->tainted) {
+        warn encode_utf8(
+            sprintf(
+                "warning: tainted %1\$s package '%2\$s', skipping\n",
+                $processable->type, $processable->name
+            )
+        );
+        return 0;
+    }
+
+    $self->source_name($processable->source_name)
+      unless length $self->source_name;
+    $self->source_version($processable->source_version)
+      unless length $self->source_version;
+
+    return 0
+      if $self->source_name ne $processable->source_name
+      || $self->source_version ne $processable->source_version;
+
+    croak encode_utf8('Please set pool directory first.')
+      unless $self->pooldir;
+
+    $processable->pooldir($self->pooldir);
+
+    croak encode_utf8('Not a supported type (' . $processable->type . ')')
+      unless exists $SUPPORTED_TYPES{$processable->type};
+
+    if ($processable->type eq 'changes') {
+        die encode_utf8('Cannot add another ' . $processable->type . ' file')
+          if $self->changes;
+        $self->changes($processable);
+
+    } elsif ($processable->type eq 'buildinfo') {
+        # Ignore multiple .buildinfo files; use the first one
+        $self->buildinfo($processable)
+          unless $self->buildinfo;
+
+    } elsif ($processable->type eq 'source'){
+        die encode_utf8('Cannot add another source package')
+          if $self->source;
+        $self->source($processable);
+
+    } else {
+        my $type = $processable->type;
+        die encode_utf8('Unknown type ' . $type)
+          unless $type eq 'binary' || $type eq 'udeb';
+
+        # check for duplicate; should be rewritten with arrays
+        my $id = $processable->identifier;
+        return 0
+          if exists $self->$type->{$id};
+
+        $self->$type->{$id} = $processable;
+    }
+
+    return 1;
+}
+
+=item get_processables
+
+Returns an array of all processables in $group.
+
+=cut
+
+sub get_processables {
+    my ($self) = @_;
+
+    my @processables;
+
+    push(@processables, $self->changes)
+      if defined $self->changes;
+
+    push(@processables, $self->source)
+      if defined $self->source;
+
+    push(@processables, $self->buildinfo)
+      if defined $self->buildinfo;
+
+    push(@processables, $self->get_installables);
+
+    return @processables;
+}
+
+=item get_installables
+
+Returns all binary (and udeb) processables in $group.
+
+If $group does not have any binary processables then an empty list is
+returned.
+
+=cut
+
+sub get_installables {
+    my ($self) = @_;
+
+    my @installables;
+
+    push(@installables, values %{$self->binary});
+    push(@installables, values %{$self->udeb});
+
+    return @installables;
+}
+
+=item direct_dependencies (PROC)
+
+If PROC is a part of the underlying processable group, this method
+returns a listref containing all the direct dependencies of PROC.  If
+PROC is not a part of the group, this returns undef.
+
+Note: Only strong dependencies (Pre-Depends and Depends) are
+considered.
+
+Note: Self-dependencies (if any) are I<not> included in the result.
+
+=cut
+
+has saved_direct_dependencies => (is => 'rw', default => sub { {} });
+
+sub direct_dependencies {
+    my ($self, $processable) = @_;
+
+    unless (keys %{$self->saved_direct_dependencies}) {
+
+        my @processables = $self->get_installables;
+
+        my %dependencies;
+        for my $that (@processables) {
+
+            my $relation = $that->relation('strong');
+            my @specific;
+
+            for my $this (@processables) {
+
+                # Ignore self deps - we have checks for that and it
+                # will just end up complicating "correctness" of
+                # otherwise simple checks.
+                next
+                  if $this->name eq $that->name;
+
+                push @specific, $this
+                  if $relation->satisfies($this->name);
+            }
+            $dependencies{$that->name} = \@specific;
+        }
+
+        $self->saved_direct_dependencies(\%dependencies);
+    }
+
+    return $self->saved_direct_dependencies->{$processable->name}
+      if $processable;
+
+    return $self->saved_direct_dependencies;
+}
+
+=item direct_reliants (PROC)
+
+If PROC is a part of the underlying processable group, this method
+returns a listref containing all the packages in the group that rely
+on PROC.  If PROC is not a part of the group, this returns undef.
+
+Note: Only strong dependencies (Pre-Depends and Depends) are
+considered.
+
+Note: Self-dependencies (if any) are I<not> included in the result.
+
+=cut
+
+has saved_direct_reliants => (is => 'rw', default => sub { {} });
+
+sub direct_reliants {
+    my ($self, $processable) = @_;
+
+    unless (keys %{$self->saved_direct_reliants}) {
+
+        my @processables = $self->get_installables;
+
+        my %reliants;
+        foreach my $that (@processables) {
+
+            my @specific;
+            foreach my $this (@processables) {
+
+                # Ignore self deps - we have checks for that and it
+                # will just end up complicating "correctness" of
+                # otherwise simple checks.
+                next
+                  if $this->name eq $that->name;
+
+                my $relation = $this->relation('strong');
+                push @specific, $this
+                  if $relation->satisfies($that->name);
+            }
+            $reliants{$that->name} = \@specific;
+        }
+
+        $self->saved_direct_reliants(\%reliants);
+    }
+
+    return $self->saved_direct_reliants->{$processable->name}
+      if $processable;
+
+    return $self->saved_direct_reliants;
+}
+
+=item spelling_exceptions
+
+Returns a hashref of words, which the spell checker should ignore.
+These words are generally based on the package names in the group to
+avoid false-positive "spelling error" when packages have "fun" names.
+
+Example: Package alot-doc (#687464)
+
+=cut
+
+has spelling_exceptions => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my @acceptable;
+
+        # this run may not have all types
+        for my $processable ($self->get_processables) {
+
+            # all processables have those
+            my @package_names= ($processable->name, $processable->source_name);
+
+            # for sources we have d/control
+            push(@package_names, $processable->debian_control->installables)
+              if $processable->type eq 'source';
+
+            push(@acceptable, @package_names);
+
+            # exempt pieces, too
+            my @package_pieces = map { split(m{-}) } @package_names;
+            push(@acceptable, @package_pieces);
+
+            my @people_names;
+            for my $role (qw(Maintainer Uploaders Changed-By)) {
+
+                my $value = $processable->fields->value($role);
+                for my $parsed (Email::Address::XS->parse($value)) {
+
+                    push(@people_names, $parsed->phrase)
+                      if length $parsed->phrase;
+                }
+            }
+
+            push(@acceptable, @people_names);
+
+            # exempt first and last name separately, too
+            my @people_pieces = map { split($SPACE) } @people_names;
+            push(@acceptable, @people_pieces);
+        }
+
+        return [uniq @acceptable];
+    }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Niels Thykier <niels@thykier.net> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+L<Lintian::Processable>
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Hint.pm b/lib/Lintian/Hint.pm
new file mode 100644
index 0000000..ee45393
--- /dev/null
+++ b/lib/Lintian/Hint.pm
@@ -0,0 +1,88 @@
+# Copyright (C) 2019-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Hint;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Hint -- Common facilities for Lintian tags found and to be issued
+
+=head1 SYNOPSIS
+
+ use Moo;
+ use namespace::clean;
+
+ with 'Lintian::Hint';
+
+=head1 DESCRIPTION
+
+Common facilities for Lintian tags found and to be issued
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item tag_name
+
+=item issued_by
+
+=item override
+
+=item masks
+
+=cut
+
+has tag_name => (is => 'rw', default => $EMPTY);
+has issued_by => (is => 'rw', default => $EMPTY);
+
+has override => (is => 'rw');
+has masks => (is => 'rw', default => sub { [] });
+
+no namespace::clean;
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Hint/Annotated.pm b/lib/Lintian/Hint/Annotated.pm
new file mode 100644
index 0000000..137f8fe
--- /dev/null
+++ b/lib/Lintian/Hint/Annotated.pm
@@ -0,0 +1,78 @@
+# Copyright (C) 2019-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Hint::Annotated;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $EMPTY => q{};
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Hint';
+
+=head1 NAME
+
+Lintian::Hint::Annotated - standard tag with arguments concatenated by space
+
+=head1 SYNOPSIS
+
+    use Lintian::Hint::Annotated;
+
+=head1 DESCRIPTION
+
+Provides a standard tag whose arguments are concatenated by a space.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item note
+
+=cut
+
+has note => (is => 'rw', default => $EMPTY);
+
+=item context
+
+=cut
+
+sub context {
+    my ($self) = @_;
+
+    return $self->note;
+}
+
+=back
+
+=cut
+
+1;
+
+__END__
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Hint/Pointed.pm b/lib/Lintian/Hint/Pointed.pm
new file mode 100644
index 0000000..be59731
--- /dev/null
+++ b/lib/Lintian/Hint/Pointed.pm
@@ -0,0 +1,88 @@
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Hint::Pointed;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Hint';
+
+=head1 NAME
+
+Lintian::Hint::Pointed - pointed tag with arguments concatenated by space
+
+=head1 SYNOPSIS
+
+    use Lintian::Hint::Pointed;
+
+=head1 DESCRIPTION
+
+Provides a pointed tag whose arguments are concatenated by a space.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item note
+
+=cut
+
+has note => (is => 'rw', default => $EMPTY);
+
+=item pointer
+
+=cut
+
+has pointer => (is => 'rw');
+
+=item context
+
+=cut
+
+sub context {
+    my ($self) = @_;
+
+    my $pointer = $self->pointer->to_string;
+    my @pieces = grep { length } ($self->note, "[$pointer]");
+
+    return join($SPACE, @pieces);
+}
+
+=back
+
+=cut
+
+1;
+
+__END__
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/IO/Select.pm b/lib/Lintian/IO/Select.pm
new file mode 100644
index 0000000..fec6a1e
--- /dev/null
+++ b/lib/Lintian/IO/Select.pm
@@ -0,0 +1,259 @@
+# Hey emacs! This is a -*- Perl -*- script!
+#
+# Lintian::IO::Select -- Perl utility functions for lintian
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::IO::Select;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+our @EXPORT_OK;
+
+BEGIN {
+
+    @EXPORT_OK = qw(
+      unpack_and_index_piped_tar
+    );
+}
+
+use Const::Fast;
+use IPC::Open3;
+use IO::Select;
+use Symbol;
+use Syntax::Keyword::Try;
+use Unicode::UTF8 qw(encode_utf8);
+
+# read up to 40kB at a time.  this happens to be 4096 "tar records"
+# (with a block-size of 512 and a block factor of 20, which appear to
+# be the defaults).  when we do full reads and writes of READ_SIZE (the
+# OS willing), the receiving end will never be with an incomplete
+# record.
+const my $TAR_RECORD_SIZE => 20 * 512;
+
+# using 4096 * $TAR_RECORD_SIZE tripped up older kernels < 5.7
+const my $READ_CHUNK => 4 * 1024;
+
+const my $EMPTY => q{};
+
+=head1 NAME
+
+Lintian::IO::Select - process functions based on IO::Select
+
+=head1 SYNOPSIS
+
+ use Lintian::IO::Select;
+
+=head1 DESCRIPTION
+
+This module contains process functions based on IO::Select.
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item unpack_and_index_piped_tar
+
+=cut
+
+sub unpack_and_index_piped_tar {
+    my ($command, $basedir) = @_;
+
+    my @pids;
+
+    my $select = IO::Select->new;
+
+    my $produce_stdin;
+    my $produce_stdout;
+    my $produce_stderr = gensym;
+
+    my @produce_command = @{$command};
+
+    my $produce_pid;
+    try {
+        $produce_pid = open3(
+            $produce_stdin, $produce_stdout,
+            $produce_stderr, @produce_command
+        );
+    } catch {
+        die map { encode_utf8($_) } $@;
+    }
+
+    close $produce_stdin;
+
+    push(@pids, $produce_pid);
+
+    $select->add($produce_stdout, $produce_stderr);
+
+    my $extract_stdin;
+    my $extract_stdout;
+    my $extract_stderr = gensym;
+
+    my @extract_command = (
+        qw(tar --no-same-owner --no-same-permissions --touch --extract --file - -C),
+        $basedir
+    );
+
+    my $extract_pid;
+    try {
+        $extract_pid = open3(
+            $extract_stdin, $extract_stdout,
+            $extract_stderr, @extract_command
+        );
+    } catch {
+        die map { encode_utf8($_) } $@;
+    }
+
+    push(@pids, $extract_pid);
+
+    $select->add($extract_stdout, $extract_stderr);
+
+    my @index_options
+      = qw(--list --verbose --utc --full-time --quoting-style=c --file -);
+
+    my $named_stdin;
+    my $named_stdout;
+    my $named_stderr = gensym;
+
+    my @named_command = ('tar', @index_options);
+
+    my $named_pid;
+    try {
+        $named_pid
+          = open3($named_stdin, $named_stdout, $named_stderr, @named_command);
+    } catch {
+        die map { encode_utf8($_) } $@;
+    }
+
+    push(@pids, $named_pid);
+
+    $select->add($named_stdout, $named_stderr);
+
+    my $numeric_stdin;
+    my $numeric_stdout;
+    my $numeric_stderr = gensym;
+
+    my @numeric_command = ('tar', '--numeric-owner', @index_options);
+
+    my $numeric_pid;
+    try {
+        $numeric_pid = open3(
+            $numeric_stdin, $numeric_stdout,
+            $numeric_stderr, @numeric_command
+        );
+    } catch {
+        die map { encode_utf8($_) } $@;
+    }
+
+    push(@pids, $numeric_pid);
+
+    $select->add($numeric_stdout, $numeric_stderr);
+
+    my $named = $EMPTY;
+    my $numeric = $EMPTY;
+
+    my $produce_errors = $EMPTY;
+    my $extract_errors = $EMPTY;
+    my $named_errors = $EMPTY;
+
+    while (my @ready = $select->can_read) {
+
+        for my $handle (@ready) {
+
+            my $buffer;
+            my $length = sysread($handle, $buffer, $READ_CHUNK);
+
+            die encode_utf8("Error from child: $!\n")
+              unless defined $length;
+
+            if ($length == 0){
+                if ($handle == $produce_stdout) {
+                    close $extract_stdin;
+                    close $named_stdin;
+                    close $numeric_stdin;
+                }
+                $select->remove($handle);
+                next;
+            }
+
+            if ($handle == $produce_stdout) {
+                print {$extract_stdin} $buffer;
+                print {$named_stdin} $buffer;
+                print {$numeric_stdin} $buffer;
+
+            } elsif ($handle == $named_stdout) {
+                $named .= $buffer;
+
+            } elsif ($handle == $numeric_stdout) {
+                $numeric .= $buffer;
+
+            } elsif ($handle == $produce_stderr) {
+                $produce_errors .= $buffer;
+
+            } elsif ($handle == $extract_stderr) {
+                $extract_errors .= $buffer;
+
+            } elsif ($handle == $named_stderr) {
+                $named_errors .= $buffer;
+
+                # } else {
+                #   die encode_utf8("Shouldn't be here\n");
+            }
+        }
+    }
+
+    close $produce_stdout;
+    close $produce_stderr;
+
+    close $extract_stdout;
+    close $extract_stderr;
+
+    close $named_stdout;
+    close $named_stderr;
+
+    close $numeric_stdout;
+    close $numeric_stderr;
+
+    waitpid($_, 0) for @pids;
+
+    my $tar_errors = ($produce_errors // $EMPTY) . ($extract_errors // $EMPTY);
+    my $index_errors = $named_errors;
+
+    return ($named, $numeric, $tar_errors, $index_errors);
+}
+
+=back
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/IPC/Run3.pm b/lib/Lintian/IPC/Run3.pm
new file mode 100644
index 0000000..e762be5
--- /dev/null
+++ b/lib/Lintian/IPC/Run3.pm
@@ -0,0 +1,135 @@
+# Hey emacs! This is a -*- Perl -*- script!
+#
+# Lintian::IPC::Run3 -- Perl utility functions for lintian
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::IPC::Run3;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+our @EXPORT_OK;
+
+BEGIN {
+
+    @EXPORT_OK = qw(
+      safe_qx
+      xargs
+    );
+}
+
+use Const::Fast;
+use IPC::Run3;
+
+const my $EMPTY => q{};
+const my $NULL => qq{\0};
+
+const my $WAIT_STATUS_SHIFT => 8;
+
+=head1 NAME
+
+Lintian::IPC::Run3 - process functions based on IPC::Run3
+
+=head1 SYNOPSIS
+
+ use Lintian::IPC::Run3 qw(safe_qx);
+
+=head1 DESCRIPTION
+
+This module contains process functions based on IPC::Run3.
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item C<safe_qx(@cmd)>
+
+Emulates the C<qx()> operator but with array argument only.
+
+=cut
+
+sub safe_qx {
+    my @command = @_;
+
+    my $stdout;
+    my $stderr;
+
+    run3(\@command, \undef, \$stdout, \$stderr);
+
+    my $exitcode = $?;
+    my $status = ($exitcode >> $WAIT_STATUS_SHIFT);
+
+    $? = $status;
+
+    return $stdout . $stderr
+      if $?;
+
+    return $stdout;
+}
+
+=item C<xargs>
+
+=cut
+
+sub xargs {
+    my ($command, $arguments, $processor) = @_;
+
+    $command //= [];
+    $arguments //= [];
+
+    return
+      unless @{$arguments};
+
+    my $input = $EMPTY;
+    $input .= $_ . $NULL for @{$arguments};
+
+    my $stdout;
+    my $stderr;
+
+    my @combined = (qw(xargs --null --no-run-if-empty), @{$command});
+
+    run3(\@combined, \$input, \$stdout, \$stderr);
+
+    my $exitcode = $?;
+    my $status = ($exitcode >> $WAIT_STATUS_SHIFT);
+
+    $processor->($stdout, $stderr, $status, @{$arguments});
+
+    return;
+}
+
+=back
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Index.pm b/lib/Lintian/Index.pm
new file mode 100644
index 0000000..b442455
--- /dev/null
+++ b/lib/Lintian/Index.pm
@@ -0,0 +1,878 @@
+# -*- perl -*- Lintian::Index
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Index;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp;
+use Const::Fast;
+use Cwd;
+use IPC::Run3;
+use List::SomeUtils qw(any);
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8 decode_utf8);
+
+use Lintian::Index::Item;
+use Lintian::IO::Select qw(unpack_and_index_piped_tar);
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Lintian::Util qw(perm2oct);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $BACKSLASH => q{\\};
+const my $ZERO => q{0};
+const my $HYPHEN => q{-};
+const my $PERCENT => q{%};
+const my $NEWLINE => qq{\n};
+
+const my $WAIT_STATUS_SHIFT => 8;
+const my $NO_LIMIT => -1;
+const my $LINES_PER_FILE => 3;
+const my $WIDELY_READABLE_FOLDER => oct(755);
+const my $WORLD_WRITABLE_FOLDER => oct(777);
+
+use Moo;
+use namespace::clean;
+
+with
+  'Lintian::Index::Ar',
+  'Lintian::Index::Elf',
+  'Lintian::Index::FileTypes',
+  'Lintian::Index::Java',
+  'Lintian::Index::Md5sums',
+  'Lintian::Index::Strings';
+
+my %FILE_CODE2LPATH_TYPE = (
+    $HYPHEN => Lintian::Index::Item::TYPE_FILE
+      | Lintian::Index::Item::OPEN_IS_OK,
+    'h' => Lintian::Index::Item::TYPE_HARDLINK
+      | Lintian::Index::Item::OPEN_IS_OK,
+    'd' => Lintian::Index::Item::TYPE_DIR| Lintian::Index::Item::FS_PATH_IS_OK,
+    'l' => Lintian::Index::Item::TYPE_SYMLINK,
+    'b' => Lintian::Index::Item::TYPE_BLOCK_DEV,
+    'c' => Lintian::Index::Item::TYPE_CHAR_DEV,
+    'p' => Lintian::Index::Item::TYPE_PIPE,
+);
+
+=head1 NAME
+
+Lintian::Index - access to collected data about the upstream (orig) sources
+
+=head1 SYNOPSIS
+
+    use Lintian::Index;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Source::Orig::Index provides an interface to collected data about the upstream (orig) sources.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item identifier
+
+=item catalog
+
+Returns a reference to a hash with elements catalogued by path names.
+
+=item C<basedir>
+
+Returns the base directory for file references.
+
+=item C<anchored>
+
+=item unpack_messages
+
+=cut
+
+has identifier => (is => 'rw', default => 'unnamed');
+
+has catalog => (
+    is => 'rw',
+    default => sub {
+        my ($self) = @_;
+
+        # create an empty root
+        my $root = Lintian::Index::Item->new;
+
+        # associate with this index
+        $root->index($self);
+
+        my %catalog;
+        $catalog{$EMPTY} = $root;
+
+        return \%catalog;
+    }
+);
+
+has basedir => (
+    is => 'rw',
+    trigger => sub {
+        my ($self, $folder) = @_;
+
+        return
+          unless length $folder;
+
+        # create directory
+        path($folder)->mkpath({ chmod => $WORLD_WRITABLE_FOLDER })
+          unless -e $folder;
+    },
+    default => $EMPTY
+);
+
+has anchored => (is => 'rw', default => 0);
+has unpack_messages => (is => 'rw', default => sub { [] });
+
+has sorted_list => (
+    is => 'ro',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my @sorted = sort { $a->name cmp $b->name } values %{$self->catalog};
+
+        # remove automatic root dir; list is sorted
+        shift @sorted;
+
+        const my @IMMUTABLE => @sorted;
+
+        return \@IMMUTABLE;
+    }
+);
+
+=item lookup (FILE)
+
+Like L</index> except orig_index is based on the "orig tarballs" of
+the source packages.
+
+For native packages L</index> and L</orig_index> are generally
+identical.
+
+NB: If sorted_index includes a debian packaging, it is was
+contained in upstream part of the source package (or the package is
+native).
+
+=cut
+
+sub lookup {
+    my ($self, $name) = @_;
+
+    # get root dir by default
+    $name //= $EMPTY;
+
+    croak encode_utf8($self->identifier . ': Name is not a string')
+      unless ref $name eq $EMPTY;
+
+    my $found = $self->catalog->{$name};
+
+    return $found
+      if defined $found;
+
+    return undef;
+}
+
+=item resolve_path
+
+=cut
+
+sub resolve_path {
+    my ($self, $name) = @_;
+
+    return $self->lookup->resolve_path($name);
+}
+
+=item create_from_basedir
+
+=cut
+
+sub create_from_basedir {
+    my ($self) = @_;
+
+    my $savedir = getcwd;
+    chdir($self->basedir)
+      or die encode_utf8(
+        $self->identifier . ': Cannot change to directory ' . $self->basedir);
+
+    # get times in UTC
+    my $TIME_STAMP
+      = $PERCENT . q{M} . $SPACE . $PERCENT . q{s} . $SPACE . $PERCENT . q{A+};
+    my $FILE_NAME = $PERCENT . q{p};
+    my $LINK_DESTINATION = $PERCENT . q{l};
+    my $NULL_BREAK = $BACKSLASH . $ZERO;
+
+    my @REQUESTED_FIELDS
+      = map { $_ . $NULL_BREAK } ($TIME_STAMP, $FILE_NAME, $LINK_DESTINATION);
+
+    my @index_command
+      = ('env', 'TZ=UTC', 'find', '-printf', join($EMPTY, @REQUESTED_FIELDS));
+    my $index_output;
+    my $index_errors;
+
+    run3(\@index_command, \undef, \$index_output, \$index_errors);
+
+    chdir($savedir)
+      or die encode_utf8(
+        $self->identifier . ": Cannot change to directory $savedir");
+
+    # allow processing of file names with non UTF-8 bytes
+    $index_errors = decode_utf8($index_errors)
+      if length $index_errors;
+
+    my $permissionspattern = qr/\S{10}/;
+    my $sizepattern = qr/\d+/;
+    my $datepattern = qr/\d{4}-\d{2}-\d{2}/;
+    my $timepattern = qr/\d{2}:\d{2}:\d{2}\.\d+/;
+    my $pathpattern = qr/[^\0]*/;
+
+    my %all;
+
+    $index_output =~ s/\0$//;
+
+    my @lines = split(/\0/, $index_output, $NO_LIMIT);
+    die encode_utf8($self->identifier
+          . ": Did not get a multiple of $LINES_PER_FILE lines from find.")
+      unless @lines % $LINES_PER_FILE == 0;
+
+    while (defined(my $first = shift @lines)) {
+
+        my $entry = Lintian::Index::Item->new;
+        $entry->index($self);
+
+        $first
+          =~ /^($permissionspattern)\ ($sizepattern)\ ($datepattern)\+($timepattern)$/s;
+
+        $entry->perm($1);
+        $entry->size($2);
+        $entry->date($3);
+        $entry->time($4);
+
+        my $name = shift @lines;
+
+        my $linktarget = shift @lines;
+
+        # for non-links, string is empty
+        $entry->link($linktarget)
+          if length $linktarget;
+
+        # find prints single dot for base; removed in next step
+        $name =~ s{^\.$}{\./}s;
+
+        # strip relative prefix
+        $name =~ s{^\./+}{}s;
+
+        # make sure directories end with a slash, except root
+        $name .= $SLASH
+          if length $name
+          && $entry->perm =~ /^d/
+          && $name !~ m{ /$ }msx;
+        $entry->name($name);
+
+        $all{$entry->name} = $entry;
+    }
+
+    $self->catalog(\%all);
+
+    my $load_errors = $self->load;
+
+    return $index_errors . $load_errors;
+}
+
+=item create_from_piped_tar
+
+=cut
+
+sub create_from_piped_tar {
+    my ($self, $command) = @_;
+
+    my $extract_dir = $self->basedir;
+
+    my ($named, $numeric, $extract_errors, $index_errors)
+      = unpack_and_index_piped_tar($command, $extract_dir);
+
+    # fix permissions
+    safe_qx('chmod', '-R', 'u+rwX,go-w', $extract_dir);
+
+    # allow processing of file names with non UTF-8 bytes
+    my @named_owner = split(/\n/, $named);
+    my @numeric_owner = split(/\n/, $numeric);
+
+    my %catalog;
+
+    for my $line (@named_owner) {
+
+        my $entry = Lintian::Index::Item->new;
+        $entry->init_from_tar_output($line);
+        $entry->index($self);
+
+        $catalog{$entry->name} = $entry;
+    }
+
+    # get numerical owners from second list
+    for my $line (@numeric_owner) {
+
+        # entry not used outside this loop
+        my $entry = Lintian::Index::Item->new;
+        $entry->init_from_tar_output($line);
+
+        die encode_utf8($self->identifier
+              . ': Numerical index lists extra files for file name '
+              . $entry->name)
+          unless exists $catalog{$entry->name};
+
+        # keep numerical uid and gid
+        $catalog{$entry->name}->uid($entry->owner);
+        $catalog{$entry->name}->gid($entry->group);
+    }
+
+    # tar produces spurious root entry when stripping slashes from member names
+    delete $catalog{$SLASH}
+      unless $self->anchored;
+
+    $self->catalog(\%catalog);
+
+    my $load_errors = $self->load;
+
+    return $extract_errors . $index_errors . $load_errors;
+}
+
+=item load
+
+=cut
+
+sub load {
+    my ($self) = @_;
+
+    my $errors = $EMPTY;
+
+    my %all = %{$self->catalog};
+
+    # set internal permissions flags
+    for my $entry (values %all) {
+
+        my $raw_type = substr($entry->perm, 0, 1);
+
+        my $operm = perm2oct($entry->perm);
+        $entry->path_info(
+            $operm | (
+                $FILE_CODE2LPATH_TYPE{$raw_type}
+                  // Lintian::Index::Item::TYPE_OTHER
+            )
+        );
+    }
+
+    # find all entries that are not regular files
+    my @nosize
+      = grep { !$_->path_info & Lintian::Index::Item::TYPE_FILE } values %all;
+
+    # reset size for anything but regular files
+    $_->size(0) for @nosize;
+
+    if ($self->anchored) {
+
+        my %relative;
+        for my $name (keys %all) {
+            my $entry = $all{$name};
+
+            # remove leading slash from absolute names
+            my $name = $entry->name;
+            $name =~ s{^/+}{}s;
+            $entry->name($name);
+
+            # remove leading slash from absolute hardlink targets
+            if ($entry->is_hardlink) {
+                my $target = $entry->link;
+                $target =~ s{^/+}{}s;
+                $entry->link($target);
+            }
+
+            $relative{$name} = $entry;
+        }
+
+        %all = %relative;
+    }
+
+    # disallow absolute names
+    die encode_utf8($self->identifier . ': Index contains absolute path names')
+      if any { $_->name =~ m{^/}s } values %all;
+
+    # disallow absolute hardlink targets
+    die encode_utf8(
+        $self->identifier . ': Index contains absolute hardlink targets')
+      if any { $_->link =~ m{^/}s } grep { $_->is_hardlink } values %all;
+
+    # add entries for missing directories
+    for my $entry (values %all) {
+
+        my $current = $entry;
+        my $parentname;
+
+        # travel up the directory tree
+        do {
+            $parentname = $current->dirname;
+
+            # insert new entry for missing intermediate directories
+            unless (exists $all{$parentname}) {
+
+                my $added = Lintian::Index::Item->new;
+                $added->index($self);
+
+                $added->name($parentname);
+                $added->path_info(
+                    $FILE_CODE2LPATH_TYPE{'d'} | $WIDELY_READABLE_FOLDER);
+
+                # random but fixed date; hint, it's a good read. :)
+                $added->date('1998-01-25');
+                $added->time('22:55:34');
+                $added->faux(1);
+
+                $all{$parentname} = $added;
+            }
+
+            $current = $all{$parentname};
+
+        } while ($parentname ne $EMPTY);
+    }
+
+    # insert root for empty tarfies like suckless-tools_45.orig.tar.xz
+    unless (exists $all{$EMPTY}) {
+
+        my $root = Lintian::Index::Item->new;
+        $root->index($self);
+
+        $root->name($EMPTY);
+        $root->path_info($FILE_CODE2LPATH_TYPE{'d'} | $WIDELY_READABLE_FOLDER);
+
+        # random but fixed date; hint, it's a good read. :)
+        $root->date('1998-01-25');
+        $root->time('22:55:34');
+        $root->faux(1);
+
+        $all{$EMPTY} = $root;
+    }
+
+    my @directories
+      = grep { $_->path_info & Lintian::Index::Item::TYPE_DIR } values %all;
+
+    # make space for children
+    my %children;
+    $children{$_->name} = [] for @directories;
+
+    # record children
+    for my $entry (values %all) {
+
+        my $parentname = $entry->dirname;
+
+        # Ensure the "root" is not its own child.  It is not really helpful
+        # from an analysis PoV and it creates ref cycles  (and by extension
+        # leaks like #695866).
+        push(@{ $children{$parentname} }, $entry)
+          unless $parentname eq $entry->name;
+    }
+
+    foreach my $entry (@directories) {
+        my %childnames
+          = map {$_->basename => $_->name }@{ $children{$entry->name} };
+        $entry->childnames(\%childnames);
+    }
+
+    # ensure root is not its own child; may create leaks like #695866
+    die encode_utf8($self->identifier . ': Root directory is its own parent')
+      if defined $all{$EMPTY} && defined $all{$EMPTY}->parent_dir;
+
+    # find all hard links
+    my @hardlinks
+      = grep { $_->path_info & Lintian::Index::Item::TYPE_HARDLINK }
+      values %all;
+
+    # catalog where they point
+    my %backlinks;
+    push(@{$backlinks{$_->link}}, $_) for @hardlinks;
+
+    # add the master files for proper sort results
+    push(@{$backlinks{$_}}, $all{$_}) for keys %backlinks;
+
+    # point hard links to shortest path
+    for my $mastername (keys %backlinks) {
+
+        my @group = @{$backlinks{$mastername}};
+
+        # sort for path length
+        my @links = sort { $a->name cmp $b->name } @group;
+
+        # pick the shortest path
+        my $preferred = shift @links;
+
+        # get the previous master entry
+        my $master = $all{$mastername};
+
+        # skip if done
+        next
+          if $preferred->name eq $master->name;
+
+        # unset link for preferred
+        $preferred->link($EMPTY);
+
+        # copy size from original
+        $preferred->size($master->size);
+
+        $preferred->path_info(
+            ($preferred->path_info& ~Lintian::Index::Item::TYPE_HARDLINK)
+            | Lintian::Index::Item::TYPE_FILE);
+
+        foreach my $pointer (@links) {
+
+            # turn into a hard link
+            $pointer->path_info(
+                ($pointer->path_info & ~Lintian::Index::Item::TYPE_FILE)
+                | Lintian::Index::Item::TYPE_HARDLINK);
+
+            # set link to preferred path
+            $pointer->link($preferred->name);
+
+            # no size for hardlinks
+            $pointer->size(0);
+        }
+    }
+
+    # make sure recorded names match hash keys
+    $all{$_}->name($_) for keys %all;
+
+    $self->catalog(\%all);
+
+    $errors .= $self->add_md5sums;
+    $errors .= $self->add_file_types;
+
+    $errors .= $self->add_ar;
+    $errors .= $self->add_elf;
+    $errors .= $self->add_java;
+    $errors .= $self->add_strings;
+
+    return $errors;
+}
+
+=item merge_in
+
+=cut
+
+sub merge_in {
+    my ($self, $other) = @_;
+
+    die encode_utf8($self->identifier
+          . ': Need same base directory ('
+          . $self->basedir . ' vs '
+          . $other->basedir . ')')
+      unless $self->basedir eq $other->basedir;
+
+    die encode_utf8($self->identifier . ': Need same anchoring status')
+      unless $self->anchored == $other->anchored;
+
+    # associate all new items with this index
+    $_->index($self) for values %{$other->catalog};
+
+    for my $item (values %{$other->catalog}) {
+
+        # do not transfer root
+        next
+          if $item->name eq $EMPTY;
+
+        # duplicates on disk are dropped with basedir segments
+        $self->catalog->{$item->name} = $item;
+
+        # when adding folder, delete potential file entry
+        my $noslash = $item->name;
+        if ($noslash =~ s{/$}{}) {
+            delete $self->catalog->{$noslash};
+        }
+    }
+
+    # add children that came from other root to current
+    my @other_childnames = keys %{$other->catalog->{$EMPTY}->childnames};
+    for my $name (@other_childnames) {
+
+        $self->catalog->{$EMPTY}->childnames->{$name}
+          = $self->catalog->{$name};
+    }
+
+    # remove items from other index
+    $other->catalog({});
+
+    # unset other base directory
+    $other->basedir($EMPTY);
+
+    return;
+}
+
+=item capture_common_prefix
+
+=cut
+
+sub capture_common_prefix {
+    my ($self) = @_;
+
+    my $new_basedir = path($self->basedir)->parent;
+
+    # do nothing in root
+    return
+      if $new_basedir eq $SLASH;
+
+    my $segment = path($self->basedir)->basename;
+    die encode_utf8($self->identifier . ': Common path segment has no length')
+      unless length $segment;
+
+    my $prefix;
+    if ($self->anchored) {
+        $prefix = $SLASH . $segment;
+    } else {
+        $prefix = $segment . $SLASH;
+    }
+
+    my $new_root = Lintian::Index::Item->new;
+
+    # associate new item with this index
+    $new_root->index($self);
+
+    $new_root->name($EMPTY);
+    $new_root->childnames({ $segment => $prefix });
+
+    # random but fixed date; hint, it's a good read. :)
+    $new_root->date('1998-01-25');
+    $new_root->time('22:55:34');
+    $new_root->path_info($FILE_CODE2LPATH_TYPE{'d'} | $WIDELY_READABLE_FOLDER);
+    $new_root->faux(1);
+
+    my %new_catalog;
+    for my $item (values %{$self->catalog}) {
+
+        # drop common prefix from name
+        my $new_name = $prefix . $item->name;
+        $item->name($new_name);
+
+        if (length $item->link) {
+
+            # add common prefix from link target
+            my $new_link = $prefix . $item->link;
+            $item->link($new_link);
+        }
+
+        # adjust references to children
+        for my $basename (keys %{$item->childnames}) {
+            $item->childnames->{$basename}
+              = $prefix . $item->childnames->{$basename};
+        }
+
+        $new_catalog{$new_name} = $item;
+    }
+
+    $new_catalog{$EMPTY} = $new_root;
+    $new_catalog{$prefix}->parent_dir($new_root);
+
+    $self->catalog(\%new_catalog);
+
+    # remove segment from base directory
+    $self->basedir($new_basedir);
+
+    return;
+}
+
+=item drop_common_prefix
+
+=cut
+
+sub drop_common_prefix {
+    my ($self) = @_;
+
+    my $errors = $EMPTY;
+
+    my @childnames = keys %{$self->catalog->{$EMPTY}->childnames};
+
+    die encode_utf8($self->identifier . ': Not exactly one top-level child')
+      unless @childnames == 1;
+
+    my $segment = $childnames[0];
+    die encode_utf8($self->identifier . ': Common path segment has no length')
+      unless length $segment;
+
+    my $new_root = $self->lookup($segment . $SLASH);
+    die encode_utf8($self->identifier . ': New root is not a directory')
+      unless $new_root->is_dir;
+
+    my $prefix;
+    if ($self->anchored) {
+        $prefix = $SLASH . $segment;
+    } else {
+        $prefix = $segment . $SLASH;
+    }
+
+    my $regex = quotemeta($prefix);
+
+    delete $self->catalog->{$EMPTY};
+
+    my %new_catalog;
+    for my $item (values %{$self->catalog}) {
+
+        # drop common prefix from name
+        my $new_name = $item->name;
+        $new_name =~ s{^$regex}{};
+        $item->name($new_name);
+
+        if (length $item->link) {
+
+            # drop common prefix from link target
+            my $new_link = $item->link;
+            $new_link =~ s{^$regex}{};
+            $item->link($new_link);
+        }
+
+        # adjust references to children
+        for my $basename (keys %{$item->childnames}) {
+            $item->childnames->{$basename} =~ s{^$regex}{};
+        }
+
+        # unsure this works, but orig not anchored
+        $new_name = $EMPTY
+          if $new_name eq $SLASH && $self->anchored;
+
+        $new_catalog{$new_name} = $item;
+    }
+
+    $self->catalog(\%new_catalog);
+
+    # add dropped segment to base directory
+    $self->basedir($self->basedir . $SLASH . $segment);
+
+    my $other_errors = $self->drop_basedir_segment;
+
+    return $errors . $other_errors;
+}
+
+=item drop_basedir_segment
+
+=cut
+
+sub drop_basedir_segment {
+    my ($self) = @_;
+
+    my $errors = $EMPTY;
+
+    my $obsolete = path($self->basedir)->basename;
+    die encode_utf8($self->identifier . ': Base directory has no name')
+      unless length $obsolete;
+
+    my $parent_dir = path($self->basedir)->parent->stringify;
+    die encode_utf8($self->identifier . ': Base directory has no parent')
+      if $parent_dir eq $SLASH;
+
+    my $grandparent_dir = path($parent_dir)->parent->stringify;
+    die encode_utf8(
+        $self->identifier . ': Will not do anything in file system root')
+      if $grandparent_dir eq $SLASH;
+
+    # destroyed when object is lost
+    my $tempdir_tiny
+      = path($grandparent_dir)->tempdir(TEMPLATE => 'customXXXXXXXX');
+
+    my $tempdir = $tempdir_tiny->stringify;
+
+    # avoids conflict in case of repeating path segments
+    for my $child (path($self->basedir)->children) {
+        my $old_name = $child->stringify;
+
+        # Perl unicode bug
+        utf8::downgrade $old_name;
+        utf8::downgrade $tempdir;
+
+        my @command = ('mv', $old_name, $tempdir);
+        my $stderr;
+        run3(\@command, \undef, \undef, \$stderr);
+        my $status = ($? >> $WAIT_STATUS_SHIFT);
+
+        # already in UTF-8
+        die $stderr
+          if $status;
+    }
+
+    rmdir $self->basedir;
+    $self->basedir($parent_dir);
+
+    for my $child ($tempdir_tiny->children) {
+        my $old_name = $child->stringify;
+
+        my $target_dir = $parent_dir . $SLASH . $child->basename;
+
+        # Perl unicode bug
+        utf8::downgrade $target_dir;
+
+        if (-e $target_dir) {
+
+            # catalog items were dropped when index was merged
+            my @command = (qw{rm -rf}, $target_dir);
+            my $stderr;
+            run3(\@command, \undef, \undef, \$stderr);
+            my $status = ($? >> $WAIT_STATUS_SHIFT);
+
+            # already in UTF-8
+            die $stderr
+              if $status;
+
+            my $display_dir
+              = path($parent_dir)->basename . $SLASH . $child->basename;
+            $errors .= "removed existing $display_dir" . $NEWLINE;
+        }
+
+        # Perl unicode bug
+        utf8::downgrade $old_name;
+        utf8::downgrade $parent_dir;
+
+        my @command = ('mv', $old_name, $parent_dir);
+        my $stderr;
+        run3(\@command, \undef, \undef, \$stderr);
+        my $status = ($? >> $WAIT_STATUS_SHIFT);
+
+        # already in UTF-8
+        die $stderr
+          if $status;
+    }
+
+    return $errors;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Index/Ar.pm b/lib/Lintian/Index/Ar.pm
new file mode 100644
index 0000000..01f3e6b
--- /dev/null
+++ b/lib/Lintian/Index/Ar.pm
@@ -0,0 +1,128 @@
+# -*- perl -*- Lintian::Index::Ar
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Index::Ar;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Cwd;
+use Path::Tiny;
+use Unicode::UTF8 qw(decode_utf8 encode_utf8);
+
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Moo::Role;
+use namespace::clean;
+
+const my $EMPTY => q{};
+const my $NEWLINE => qq{\n};
+
+=head1 NAME
+
+Lintian::Index::Ar - binary symbol information.
+
+=head1 SYNOPSIS
+
+    use Lintian::Index;
+
+=head1 DESCRIPTION
+
+Lintian::Index::Ar binary symbol information.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item add_ar
+
+=cut
+
+sub add_ar {
+    my ($self) = @_;
+
+    my $savedir = getcwd;
+    chdir($self->basedir)
+      or die encode_utf8(
+        $self->identifier . ': Cannot change to directory ' . $self->basedir);
+
+    my $errors = $EMPTY;
+
+    my @archives
+      = grep { $_->name =~ / [.]a $/msx && $_->is_regular_file }
+      @{$self->sorted_list};
+
+    for my $archive (@archives) {
+
+        # skip empty archives to avoid ar error message; happens in tests
+        next
+          unless $archive->size;
+
+        my %ar_info;
+
+    # fails silently for non-ar files (#934899); probably creates empty entries
+        my $bytes = safe_qx(qw{ar t}, $archive);
+        if ($?) {
+            $errors .= "ar failed for $archive" . $NEWLINE;
+            next;
+        }
+
+        my $output = decode_utf8($bytes);
+        my @members = split(/\n/, $output);
+
+        my $count = 1;
+        for my $member (@members) {
+
+            # more info could be added with -v above
+            $ar_info{$count}{name} = $member;
+
+        } continue {
+            $count++;
+        }
+
+        $archive->ar_info(\%ar_info);
+    }
+
+    chdir($savedir)
+      or die encode_utf8(
+        $self->identifier . ": Cannot change to directory $savedir");
+
+    return $errors;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Index/Elf.pm b/lib/Lintian/Index/Elf.pm
new file mode 100644
index 0000000..1fe4d7a
--- /dev/null
+++ b/lib/Lintian/Index/Elf.pm
@@ -0,0 +1,739 @@
+# -*- perl -*- Lintian::Index::Elf
+#
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2008 Adam D. Barratt
+# Copyright (C) 2017-2018 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2022 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Index::Elf;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use bignum qw(hex);
+
+use Const::Fast;
+use Cwd;
+use IPC::Run3;
+use Unicode::UTF8 qw(encode_utf8 valid_utf8 decode_utf8);
+
+use Lintian::Elf::Section;
+use Lintian::Elf::Symbol;
+use Lintian::Storage::MLDBM;
+
+use Moo::Role;
+use namespace::clean;
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $HYPHEN => q{-};
+const my $NEWLINE => qq{\n};
+
+const my $LINES_PER_FILE => 3;
+
+=head1 NAME
+
+Lintian::Index::Elf - binary symbol information.
+
+=head1 SYNOPSIS
+
+    use Lintian::Index;
+
+=head1 DESCRIPTION
+
+Lintian::Index::Elf binary symbol information.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item elf_storage
+
+=cut
+
+has elf_storage => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $storage = Lintian::Storage::MLDBM->new;
+        $storage->create('elf');
+
+        return $storage;
+    }
+);
+
+=item elf_storage_by_member
+
+=cut
+
+has elf_storage_by_member => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $storage = Lintian::Storage::MLDBM->new;
+        $storage->create('elf-by-member');
+
+        return $storage;
+    }
+);
+
+=item add_elf
+
+=cut
+
+sub add_elf {
+    my ($self) = @_;
+
+    my $savedir = getcwd;
+    chdir($self->basedir)
+      or die encode_utf8(
+        $self->identifier . ': Cannot change to directory ' . $self->basedir);
+
+    my $errors = $EMPTY;
+
+    my @files = grep { $_->is_file } @{$self->sorted_list};
+
+    # must be ELF or static library
+    my @with_objects = grep {
+        $_->file_type =~ /\bELF\b/
+          || ( $_->file_type =~ /\bcurrent ar archive\b/
+            && $_->name =~ /\.a$/)
+    } @files;
+
+    for my $file (@with_objects) {
+
+        local $SIG{__WARN__}= sub {
+            warn encode_utf8($self->identifier
+                  . ': Warning while running readelf on'
+                  . $file->name
+                  . ": $_[0]");
+        };
+
+        my @command = (qw{readelf --all --wide}, $file->name);
+        my $combined_bytes;
+
+        run3(\@command, \undef, \$combined_bytes, \$combined_bytes);
+
+        next
+          unless length $combined_bytes;
+
+        my $combined_output;
+
+        if (valid_utf8($combined_bytes)) {
+            $combined_output = decode_utf8($combined_bytes);
+
+        } else {
+            $combined_output = $combined_bytes;
+            $errors .= "Output from '@command' is not valid UTF-8" . $NEWLINE;
+        }
+
+        # each object file in an archive gets its own File section
+        my @per_files = split(/^(File): (.*)$/m, $combined_output);
+        shift @per_files while @per_files && $per_files[0] ne 'File';
+
+        @per_files = ($combined_output)
+          unless @per_files;
+
+        # Special case - readelf will not prefix the output with "File:
+        # $name" if it only gets one ELF file argument, so act as if it did...
+        # (but it does "the right thing" if passed a static lib >.>)
+        #
+        # - In fact, if readelf always emitted that File: header, we could
+        #   simply use xargs directly on readelf and just parse its output
+        #   in the loop below.
+        if (@per_files == 1) {
+            unshift(@per_files, $file->name);
+            unshift(@per_files, 'File');
+        }
+
+        unless (@per_files % $LINES_PER_FILE == 0) {
+
+            $errors
+              .= "Parsed data from readelf is not a multiple of $LINES_PER_FILE for $file"
+              . $NEWLINE;
+            next;
+        }
+
+        while (defined(my $fixed = shift @per_files)) {
+
+            my $recorded_name = shift @per_files;
+            my $per_file = shift @per_files;
+
+            unless ($fixed eq 'File') {
+                $errors .= "Unknown output from readelf for $file" . $NEWLINE;
+                next;
+            }
+
+            unless (length $recorded_name) {
+                $errors .= "No file name from readelf for $file" . $NEWLINE;
+                next;
+            }
+
+            my ($container, $member) = ($recorded_name =~ /^(.*)\(([^)]+)\)$/);
+
+            $container = $recorded_name
+              unless defined $container && defined $member;
+
+            unless ($container eq $file->name) {
+                $errors
+                  .= "Container not same as file name ($container vs $file)"
+                  . $NEWLINE;
+                next;
+            }
+
+            # ignore empty archives, such as in musl-dev_1.2.1-1_amd64.deb
+            next
+              unless length $per_file;
+
+            my $object_name;
+            if ($recorded_name =~ m{^(?:.+)\(([^/\)]+)\)$}){
+
+                # object file in a static lib.
+                $object_name = $1;
+            }
+
+            parse_per_file($file, $object_name, $per_file);
+        }
+    }
+
+    chdir($savedir)
+      or die encode_utf8(
+        $self->identifier . ": Cannot change to directory $savedir");
+
+    return $errors;
+}
+
+=item parse_per_file
+
+=cut
+
+sub parse_per_file {
+    my ($file, $object_name, $from_readelf) = @_;
+
+    my %by_object;
+
+    $by_object{READELF} = $from_readelf;
+
+    # sometimes there are three blank lines; seen on armhf
+    my @paragraphs = split(/\n{2,}/, $from_readelf);
+
+    for my $paragraph (@paragraphs) {
+
+        my ($first, $bulk) = split(m{\n}, $paragraph, 2);
+
+        if ($first =~ /^ELF Header:/) {
+            elf_header($bulk, \%by_object);
+            next;
+        }
+
+        if ($first =~ /^Program Headers:/) {
+            program_headers($bulk, \%by_object);
+            next;
+        }
+
+        if ($first =~ /^Dynamic section at offset .*:/) {
+            dynamic_section($bulk, \%by_object);
+            next;
+        }
+
+        if ($first =~ /^Section Headers:/) {
+            section_headers($bulk, \%by_object);
+            next;
+        }
+
+        if ($first =~ /^Symbol table '.dynsym'/) {
+            symbol_table($bulk, \%by_object);
+            next;
+        }
+
+        if ($first =~ /^Version symbols section /) {
+            version_symbols($bulk, \%by_object);
+            next;
+        }
+
+        if ($first =~ /^There is no dynamic section in this file/) {
+            # a dynamic section was declared but it's empty.
+            $by_object{'BAD-DYNAMIC-TABLE'} = 1
+              if exists $by_object{PH}{DYNAMIC};
+            next;
+        }
+    }
+
+    my %section_name_by_number;
+    for my $name (keys %{$by_object{SH} // {}}) {
+
+        my $number = $by_object{SH}{$name}{number};
+        $section_name_by_number{$number} = $name;
+    }
+
+    for my $symbol_number (keys %{$by_object{'DYNAMIC-SYMBOLS'}}) {
+
+        my $symbol_name
+          = $by_object{'DYNAMIC-SYMBOLS'}{$symbol_number}{symbol_name};
+        my $section_number
+          = $by_object{'DYNAMIC-SYMBOLS'}{$symbol_number}{section_number};
+
+        my $symbol_version;
+
+        if ($symbol_name =~ m{^ (.*) @ (.*) \s [(] .* [)] $}x) {
+
+            $symbol_name = $1;
+            $symbol_version = $2;
+
+        } else {
+            $symbol_version = $by_object{'SYMBOL-VERSIONS'}{$symbol_number}
+              // $EMPTY;
+
+            if (   $symbol_version eq '*local*'
+                || $symbol_version eq '*global*'){
+
+                if ($section_number eq 'UND') {
+                    $symbol_version = $EMPTY;
+
+                } else {
+                    $symbol_version = 'Base';
+                }
+
+            } elsif ($symbol_version eq '()') {
+                $symbol_version = '(Base)';
+            }
+        }
+
+        # happens once or twice for regular binaries
+        next
+          unless length $symbol_name;
+
+        # look up numbered section
+        my $section_name = $section_name_by_number{$section_number}
+          // $section_number;
+
+        my $symbol = Lintian::Elf::Symbol->new;
+        $symbol->section($section_name);
+        $symbol->version($symbol_version);
+        $symbol->name($symbol_name);
+
+        push(@{ $by_object{SYMBOLS} }, $symbol);
+    }
+
+    if (length $object_name) {
+
+        # object file in a static lib.
+        $file->elf_by_member($object_name, \%by_object);
+
+    } else {
+        $file->elf(\%by_object);
+    }
+
+    return;
+}
+
+=item elf_header
+
+=cut
+
+sub elf_header {
+    my ($text, $by_object) = @_;
+
+    my @lines = split(m{\n}, $text);
+
+    for my $line (@lines) {
+
+        next
+          if divert_error('ELF header', $line, $by_object);
+
+        my ($field, $value) = split(/:/, $line, 2);
+
+        # trim both ends
+        $field =~ s/^\s+|\s+$//g;
+        $value =~ s/^\s+|\s+$//g;
+
+        next
+          unless length $field && length $value;
+
+        $by_object->{'ELF-HEADER'}{$field} = $value;
+    }
+
+    return;
+}
+
+=item program_headers
+
+=cut
+
+sub program_headers {
+    my ($text, $by_object) = @_;
+
+    my @lines = split(m{\n}, $text);
+
+    while (defined(my $line = shift @lines)) {
+
+        next
+          if divert_error('program headers', $line, $by_object);
+
+        if ($line =~ m{^ \s* (\S+) \s* (?:(?:\S+\s+){4}) \S+ \s (...) }x) {
+
+            my $header = $1;
+            my $flags = $2;
+
+            $header =~ s/^GNU_//g;
+
+            next
+              if $header eq 'Type';
+
+            my $newflags = $EMPTY;
+            $newflags .= ($flags =~ /R/) ? 'r' : $HYPHEN;
+            $newflags .= ($flags =~ /W/) ? 'w' : $HYPHEN;
+            $newflags .= ($flags =~ /E/) ? 'x' : $HYPHEN;
+
+            $by_object->{PH}{$header}{flags} = $newflags;
+
+            if ($header eq 'INTERP' && @lines) {
+                # Check if the next line is the "requesting an interpreter"
+                # (readelf appears to always emit on the next line if at all)
+                my $next_line = $lines[0];
+
+                if ($next_line
+                    =~ m{ [[] Requesting \s program \s interpreter: \s ([^\]]+) []] }x
+                ){
+
+                    my $interpreter = $1;
+
+                    $by_object->{INTERP} = $interpreter;
+
+                    # discard line
+                    shift @lines;
+                }
+            }
+        }
+    }
+
+    return;
+}
+
+=item dynamic_section
+
+=cut
+
+sub dynamic_section {
+    my ($text, $by_object) = @_;
+
+    my @lines = split(m{\n}, $text);
+
+    while (defined(my $line = shift @lines)) {
+
+        next
+          if divert_error('dynamic section', $line, $by_object);
+
+        if ($line
+            =~ m{^ \s* 0x (?:[0-9A-F]+) \s+ [(] (.*?) [)] \s+ ([\x21-\x7f][\x20-\x7f]*) \Z}ix
+        ) {
+
+            my $type = $1;
+            my $remainder = $2;
+
+            my $keep = 0;
+
+            if ($type eq 'RPATH' || $type eq 'RUNPATH') {
+                $remainder =~ s{^ .* [[] }{}x;
+                $remainder =~ s{ []] \s* $}{}x;
+                $keep = 1;
+
+            } elsif ($type eq 'TEXTREL' || $type eq 'DEBUG') {
+                $keep = 1;
+
+            } elsif ($type eq 'FLAGS_1') {
+                # Will contain "NOW" if the binary was built with -Wl,-z,now
+                $remainder =~ s/^Flags:\s*//i;
+                $keep = 1;
+
+            } elsif (($type eq 'FLAGS' && $remainder =~ m/\bBIND_NOW\b/)
+                || $type eq 'BIND_NOW') {
+
+                # Variants of bindnow
+                $type = 'FLAGS_1';
+                $remainder = 'NOW';
+                $keep = 1;
+            }
+
+            $keep = 1
+              if $remainder
+              =~ s{^ (?: Shared \s library | Library \s soname ) : \s [[] (.*) []] }{$1}x;
+
+            next
+              unless $keep;
+
+            # Here we just need RPATH and NEEDS, so ignore the rest for now
+            if ($type eq 'RPATH' || $type eq 'RUNPATH') {
+
+                # RPATH is like PATH
+                my @components = split(/:/, $remainder);
+                $by_object->{$type}{$_} = 1 for @components;
+
+            } elsif ($type eq 'NEEDED' || $type eq 'SONAME') {
+                push(@{ $by_object->{$type} }, $remainder);
+
+            } elsif ($type eq 'TEXTREL' || $type eq 'DEBUG') {
+                $by_object->{$type} = 1;
+
+            } elsif ($type eq 'FLAGS_1') {
+
+                my @flags = split(/\s+/, $remainder);
+                $by_object->{$type}{$_} = 1 for @flags;
+            }
+        }
+    }
+
+    return;
+}
+
+=item section_headers
+
+=cut
+
+sub section_headers {
+    my ($text, $by_object) = @_;
+
+    const my $TOTAL_FIELDS => 11;
+
+    my @lines = split(m{\n}, $text);
+
+    die 'No column labels.'
+      unless @lines;
+
+    my $first = shift @lines;
+
+    my %labels_by_column;
+
+    my $column = 1;
+    for my $label (split($SPACE, $first)) {
+
+        $label =~ s{^ [[] }{}x;
+        $label =~ s{ []] $}{}x;
+
+        $labels_by_column{$column} = $label;
+
+    } continue {
+        ++$column;
+    }
+
+    die 'Not enough column labels.'
+      if keys %labels_by_column != $TOTAL_FIELDS;
+
+    my $row = 1;
+    while (defined(my $line = shift @lines)) {
+
+        next
+          if divert_error('section headers', $line, $by_object);
+
+        last
+          if $line =~ /^Key to Flags:/;
+
+        my %section_header;
+
+        my @matches = (
+            $line =~ m{^ \s*
+                         [[] \s* (\S+) []] \s    # Nr
+                         (\S+)?      \s+         # Name
+                         (\S+)       \s+         # Type
+                         ([0-9a-f]+) \s          # Address/Addr
+                         ([0-9a-f]+) \s          # Off
+                         ([0-9a-f]+) \s          # Size
+                         (\S+)       \s+         # ES
+                         (\S+)?      \s+         # Flg
+                         (\S+)       \s+         # Lk
+                         (\S+)       \s+         # Inf
+                         (\S+)                   # Al
+                       $}x
+        );
+
+        if (@matches != $TOTAL_FIELDS) {
+
+            warn "Parse error in readelf section headers [row $row]: $line";
+            next;
+        }
+
+        for my $column (keys %labels_by_column) {
+
+            my $label = $labels_by_column{$column};
+            my $value = $matches[$column -1] // $EMPTY;
+
+            $section_header{$label} = $value;
+        }
+
+        # http://sco.com/developers/gabi/latest/ch4.sheader.html
+        my $section = Lintian::Elf::Section->new;
+        $section->number($section_header{Nr});
+        $section->name($section_header{Name});
+        $section->type($section_header{Type});
+
+        # readelf uses both
+        $section->address(
+            hex($section_header{Address} // $section_header{Addr}));
+        $section->offset(hex($section_header{Off}));
+        $section->size(hex($section_header{Size}));
+        $section->entry_size(hex($section_header{ES}));
+        $section->flags($section_header{Flg});
+        $section->index_link(hex($section_header{Lk}));
+        $section->index_info(hex($section_header{Inf}));
+        $section->alignment(hex($section_header{Al}));
+
+        die 'No section number.'
+          unless length $section->number;
+
+        $by_object->{'SECTION-HEADERS'}{$section->number} = $section;
+
+    } continue {
+        ++$row;
+    }
+
+    return;
+}
+
+=item symbol_table
+
+=cut
+
+sub symbol_table {
+    my ($text, $by_object) = @_;
+
+    # We (sometimes) need to read the "Version symbols section" first to
+    # use this data and readelf tends to print after this section, so
+    # save for later.
+
+    my @lines = split(m{\n}, $text);
+
+    while (defined(my $line = shift @lines)) {
+
+        next
+          if divert_error('symbol table', $line, $by_object);
+
+        if ($line
+            =~ m{^ \s* (\d+) : \s* [0-9a-f]+ \s+ \d+ \s+ (?:(?:\S+\s+){3}) (?: [[] .* []] \s+)? (\S+) \s+ (.*) \Z}x
+        ) {
+
+            my $symbol_number = $1;
+            my $section_number = $2;
+            my $symbol_name = $3;
+
+            $by_object->{'DYNAMIC-SYMBOLS'}{$symbol_number}{section_number}
+              = $section_number;
+            $by_object->{'DYNAMIC-SYMBOLS'}{$symbol_number}{symbol_name}
+              = $symbol_name;
+        }
+    }
+
+    return;
+}
+
+=item version_symbols
+
+=cut
+
+sub version_symbols {
+    my ($text, $by_object) = @_;
+
+    my @lines = split(m{\n}, $text);
+
+    while (defined(my $line = shift @lines)) {
+
+        next
+          if divert_error('version symbols', $line, $by_object);
+
+        if ($line
+            =~ m{^ \s* [0-9a-f]+ : \s* \S+ \s* (?: [(] \S+ [)] )? (?: \s | \Z ) }xi
+        ){
+
+            while ($line
+                =~ m{ ([0-9a-f]+ h?) \s* (?: [(] (\S+) [)] )? (?: \s | \Z ) }cgix
+            ) {
+
+                my $symbol_number = $1;
+                my $symbol_version = $2;
+
+                # for libfuse2_2.9.9-3_amd64.deb
+                next
+                  unless length $symbol_version;
+
+                $symbol_version = "($symbol_version)"
+                  if $symbol_number =~ m{ h $}x;
+
+                $by_object->{'SYMBOL-VERSIONS'}{$symbol_number}
+                  = $symbol_version;
+            }
+        }
+    }
+
+    return;
+}
+
+=item divert_error
+
+=cut
+
+sub divert_error {
+    my ($section, $line, $by_object) = @_;
+
+    return 0
+      unless $line =~ s{^ readelf: \s+ }{}x;
+
+    if ($line =~ s{^ Error: \s+ }{}x) {
+
+        my $message = "In $section: $line";
+
+        $by_object->{ERRORS} //= [];
+        push(@{$by_object->{ERRORS}}, $message);
+
+        return 1;
+    }
+
+    if ($line =~ s{^ Warning: \s+ }{}x) {
+
+        my $message = "In $section: $line";
+
+        $by_object->{WARNINGS} //= [];
+        push(@{$by_object->{WARNINGS}}, $message);
+
+        return 1;
+    }
+
+    return 0;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Index/FileTypes.pm b/lib/Lintian/Index/FileTypes.pm
new file mode 100644
index 0000000..a71efb3
--- /dev/null
+++ b/lib/Lintian/Index/FileTypes.pm
@@ -0,0 +1,195 @@
+# -*- perl -*- Lintian::Index::FileTypes
+#
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Index::FileTypes;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Cwd;
+use Unicode::UTF8 qw(encode_utf8 decode_utf8);
+
+use Lintian::IPC::Run3 qw(xargs);
+
+use Moo::Role;
+use namespace::clean;
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $COMMA => q{,};
+const my $NEWLINE => qq{\n};
+
+const my $KEEP_EMPTY_FIELDS => -1;
+const my $GZIP_MAGIC_SIZE => 9;
+const my $GZIP_MAGIC_BYTES => 0x1f8b;
+
+=head1 NAME
+
+Lintian::Index::FileTypes - determine file type via magic.
+
+=head1 SYNOPSIS
+
+    use Lintian::Index;
+
+=head1 DESCRIPTION
+
+Lintian::Index::FileTypes determine file type via magic.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item add_file_types
+
+=cut
+
+sub add_file_types {
+    my ($self) = @_;
+
+    my $savedir = getcwd;
+    chdir $self->basedir
+      or die encode_utf8(
+        $self->identifier . ': Cannot change to directory ' . $self->basedir);
+
+    my $errors = $EMPTY;
+
+    my @files = grep { $_->is_file } @{$self->sorted_list};
+    my @names = map { $_->name } @files;
+
+    my @command = qw(file --raw --no-pad --print0 --print0 --);
+
+    my %file_types;
+
+    xargs(
+        \@command,
+        \@names,
+        sub {
+            my ($stdout, $stderr, $status, @partial) = @_;
+
+            # ignore failures if possible; file returns non-zero and
+            # "ERROR" on parse errors but output is still usable
+
+            # undecoded split allows names with non UTF-8 bytes
+            $stdout =~ s{ \0 $}{}x;
+
+            my @lines = split(m{\0}, $stdout, $KEEP_EMPTY_FIELDS);
+
+            unless (@lines % 2 == 0) {
+                $errors
+                  .= 'Did not get an even number lines from file command.'
+                  . $NEWLINE;
+                return;
+            }
+
+            while (defined(my $path = shift @lines)) {
+
+                my $type = shift @lines;
+
+                unless (length $path && length $type) {
+                    $errors
+                      .= "syntax error in file-info output: '$path' '$type'"
+                      . $NEWLINE;
+                    next;
+                }
+
+                # drop relative prefix, if present
+                $path =~ s{^ [.]/ }{}x;
+
+                $file_types{$path} = $self->adjust_type($path, $type);
+            }
+
+            return;
+        }
+    );
+
+    $_->file_type($file_types{$_->name}) for @files;
+
+    chdir $savedir
+      or die encode_utf8(
+        $self->identifier . ": Cannot change to directory $savedir");
+
+    return $errors;
+}
+
+=item adjust_type
+
+=cut
+
+# some files need to be corrected
+sub adjust_type {
+    my ($self, $name, $file_type) = @_;
+
+    if ($name =~ m{ [.]gz $}ix && $file_type !~ /compressed/) {
+
+        my $item = $self->lookup($name);
+
+        die encode_utf8("Cannot find file $name in index")
+          unless $item;
+
+        my $buffer = $item->magic($GZIP_MAGIC_SIZE);
+        if (length $buffer) {
+
+            # translation of the unpack
+            #  nn nn ,  NN NN NN NN, nn nn, cc     - bytes read
+            #  $magic,  __ __ __ __, __ __, $comp  - variables
+            my ($magic, undef, undef, $compression) = unpack('nNnc', $buffer);
+
+            # gzip file magic
+            if ($magic == $GZIP_MAGIC_BYTES) {
+
+                my $augment = 'gzip compressed data';
+
+                # 2 for max compression; RFC1952 suggests this is a
+                # flag and not a value, hence bit operation
+                $augment .= $COMMA . $SPACE . 'max compression'
+                  if $compression & 2;
+
+                return $file_type . $COMMA . $SPACE . $augment;
+            }
+        }
+    }
+
+    # some TFMs are categorized as gzip, see Bug#963589
+    return 'data'
+      if $name =~ m{ [.]tfm $}ix
+      && $file_type =~ /gzip compressed data/;
+
+    return $file_type;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Index/Item.pm b/lib/Lintian/Index/Item.pm
new file mode 100644
index 0000000..7ef6c09
--- /dev/null
+++ b/lib/Lintian/Index/Item.pm
@@ -0,0 +1,1567 @@
+# -*- perl -*-
+# Lintian::Index::Item -- Representation of path entry in a package
+#
+# Copyright (C) 2011 Niels Thykier
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Index::Item;
+
+use v5.20;
+use warnings;
+use utf8;
+use autodie qw(open);
+
+use Carp qw(croak confess);
+use Const::Fast;
+use Date::Parse qw(str2time);
+use List::SomeUtils qw(all);
+use Path::Tiny;
+use Syntax::Keyword::Try;
+use Text::Balanced qw(extract_delimited);
+use Unicode::UTF8 qw(valid_utf8 decode_utf8 encode_utf8);
+
+use Lintian::Pointer::Item;
+use Lintian::SlidingWindow;
+use Lintian::Util qw(normalize_link_target);
+
+use Moo;
+use namespace::clean;
+
+use constant {
+    TYPE_FILE      => 0x00_01_00_00,
+    TYPE_HARDLINK  => 0x00_02_00_00,
+    TYPE_DIR       => 0x00_04_00_00,
+    TYPE_SYMLINK   => 0x00_08_00_00,
+    TYPE_BLOCK_DEV => 0x00_10_00_00,
+    TYPE_CHAR_DEV  => 0x00_20_00_00,
+    TYPE_PIPE      => 0x00_40_00_00,
+    TYPE_OTHER     => 0x00_80_00_00,
+    TYPE_MASK      => 0x00_ff_00_00,
+
+    UNSAFE_PATH    => 0x01_00_00_00,
+    FS_PATH_IS_OK  => 0x02_00_00_00,
+    OPEN_IS_OK     => 0x06_00_00_00, # Implies FS_PATH_IS_OK
+    ACCESS_INFO    => 0x07_00_00_00,
+    # 0o6777 == 0xdff, which covers set[ug]id + sticky bit.  Accordingly,
+    # 0xffff should be more than sufficient for the foreseeable future.
+    OPERM_MASK     => 0x00_00_ff_ff,
+};
+
+use overload (
+    q{""} => \&_as_string,
+    'qr' => \&_as_regex_ref,
+    'bool' => \&_bool,
+    q{!} => \&_bool_not,
+    q{.} => \&_str_concat,
+    'cmp' => \&_str_cmp,
+    'eq' => \&_str_eq,
+    'ne' => \&_str_ne,
+    'fallback' => 0,
+);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $DOT => q{.};
+const my $DOUBLE_DOT => q{..};
+const my $DOUBLE_QUOTE => q{"};
+const my $BACKSLASH => q{\\};
+const my $HASHBANG => q{#!};
+
+const my $MAXIMUM_LINK_DEPTH => 18;
+
+const my $BYTE_MAXIMUM => 255;
+const my $SINGLE_OCTAL_MASK => oct(7);
+const my $DUAL_OCTAL_MASK => oct(77);
+
+const my $ELF_MAGIC_SIZE => 4;
+const my $LINCITY_MAGIC_SIZE => 6;
+const my $SHELL_SCRIPT_MAGIC_SIZE => 2;
+
+const my $READ_BITS => oct(444);
+const my $WRITE_BITS => oct(222);
+const my $EXECUTABLE_BITS => oct(111);
+
+const my $SETUID => oct(4000);
+const my $SETGID => oct(2000);
+
+=head1 NAME
+
+Lintian::Index::Item - Lintian representation of a path entry in a package
+
+=head1 SYNOPSIS
+
+    my ($name, $type, $dir) = ('lintian', 'source', '/path/to/entry');
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item init_from_tar_output
+
+=item get_quoted_filename
+
+=item unescape_c_style
+
+=cut
+
+my $datepattern = qr/\d{4}-\d{2}-\d{2}/;
+my $timepattern = qr/\d{2}\:\d{2}(?:\:\d{2}(?:\.\d+)?)?/;
+my $symlinkpattern = qr/\s+->\s+/;
+my $hardlinkpattern = qr/\s+link\s+to\s+/;
+
+# adapted from https://www.perlmonks.org/?node_id=1056606
+my %T = (
+    (map {chr() => chr} 0..$BYTE_MAXIMUM),
+    (map {sprintf('%o',$_) => chr} 0..($BYTE_MAXIMUM & $SINGLE_OCTAL_MASK)),
+    (map {sprintf('%02o',$_) => chr} 0..($BYTE_MAXIMUM & $DUAL_OCTAL_MASK)),
+    (map {sprintf('%03o',$_) => chr} 0..$BYTE_MAXIMUM),
+    (split //, "r\rn\nb\ba\af\ft\tv\013")
+);
+
+sub unescape_c_style {
+    my ($escaped) = @_;
+
+    (my $result = $escaped) =~ s/\\([0-7]{1,3}|.)/$T{$1}/g;
+
+    return $result;
+}
+
+sub get_quoted_filename {
+    my ($unknown, $skip) = @_;
+
+    # extract quoted file name
+    my ($delimited, $extra)
+      = extract_delimited($unknown, $DOUBLE_QUOTE, $skip, $BACKSLASH);
+
+    return (undef, undef)
+      unless defined $delimited;
+
+    # drop quotes
+    my $cstylename = substr($delimited, 1, (length $delimited) - 2);
+
+    # convert c-style escapes
+    my $name = unescape_c_style($cstylename);
+
+    return ($name, $extra);
+}
+
+sub init_from_tar_output {
+    my ($self, $line) = @_;
+
+    chomp $line;
+
+    # allow spaces in ownership and filenames (#895175 and #950589)
+
+    my ($initial, $size, $date, $time, $remainder)
+      = split(/\s+(\d+)\s+($datepattern)\s+($timepattern)\s+/, $line,2);
+
+    die encode_utf8(
+        $self->index->identifier . ": Cannot parse tar output: $line")
+      unless all { defined } ($initial, $size, $date, $time, $remainder);
+
+    $self->size($size);
+    $self->date($date);
+    $self->time($time);
+
+    my ($permissions, $ownership) = split(/\s+/, $initial, 2);
+    die encode_utf8($self->index->identifier
+          .": Cannot parse permissions and ownership in tar output: $line")
+      unless all { defined } ($permissions, $ownership);
+
+    $self->perm($permissions);
+
+    my ($owner, $group) = split(qr{/}, $ownership, 2);
+    die encode_utf8($self->index->identifier
+          . ": Cannot parse owner and group in tar output: $line")
+      unless all { defined } ($owner, $group);
+
+    $self->owner($owner);
+    $self->group($group);
+
+    my ($name, $extra) = get_quoted_filename($remainder, $EMPTY);
+    die encode_utf8($self->index->identifier
+          . ": Cannot parse file name in tar output: $line")
+      unless all { defined } ($name, $extra);
+
+    # strip relative prefix
+    $name =~ s{^\./+}{}s;
+
+    # slashes cannot appear in names but are sometimes doubled
+    # as in emboss-explorer_2.2.0-10.dsc
+    # better implemented in a Moo trigger on the attribute
+    $name =~ s{/+}{/}g;
+
+    # make sure directories end with a slash, except root
+    $name .= $SLASH
+      if length $name
+      && $self->perm =~ / ^d /msx
+      && $name !~ m{ /$ }msx;
+
+    $self->name($name);
+
+    # look for symbolic link target
+    if ($self->perm =~ /^l/) {
+
+        my ($linktarget, undef) = get_quoted_filename($extra, $symlinkpattern);
+        die encode_utf8($self->index->identifier
+              .": Cannot parse symbolic link target in tar output: $line")
+          unless defined $linktarget;
+
+        # do not remove multiple slashes from symlink targets
+        # caught by symlink-has-double-slash, which is tested
+        # leaves resolution of these links unsolved
+
+        # do not strip relative prefix for symbolic links
+        $self->link($linktarget);
+    }
+
+    # look for hard link target
+    if ($self->perm =~ /^h/) {
+
+        my ($linktarget, undef)= get_quoted_filename($extra, $hardlinkpattern);
+        die encode_utf8($self->index->identifier
+              . ": Cannot parse hard link target in tar output: $line")
+          unless defined $linktarget;
+
+        # strip relative prefix
+        $linktarget =~ s{^\./+}{}s;
+
+        # slashes cannot appear in names but are sometimes doubled
+        # as in emboss-explorer_2.2.0-10.dsc
+        # better implemented in a Moo trigger on the attribute, but requires
+        # separate attributes for hard and symbolic link targets
+        $linktarget =~ s{/+}{/}g;
+
+        $self->link($linktarget);
+    }
+
+    return;
+}
+
+=item bytes_match(REGEX)
+
+Returns the matched string if REGEX matches the file's byte contents,
+or $EMPTY otherwise.
+
+=cut
+
+sub bytes_match {
+    my ($self, $regex) = @_;
+
+    return $EMPTY
+      unless $self->is_file;
+
+    return $EMPTY
+      unless $self->is_open_ok;
+
+    return $EMPTY
+      unless length $regex;
+
+    open(my $fd, '<:raw', $self->unpacked_path);
+    my $sfd = Lintian::SlidingWindow->new;
+    $sfd->handle($fd);
+
+    my $match;
+    while (my $block = $sfd->readwindow) {
+
+        if ($block =~ /($regex)/) {
+
+            $match = $1;
+            last;
+        }
+    }
+
+    close $fd;
+
+    return $match // $EMPTY;
+}
+
+=item mentions_in_operation(REGEX)
+
+Returns the matched string if REGEX matches in a file location
+that is likely an operation (vs text), or $EMPTY otherwise.
+
+=cut
+
+sub mentions_in_operation {
+    my ($self, $regex) = @_;
+
+    # prefer strings(1) output (eg. for ELF) if we have it
+    # may not work as expected on ELF due to ld's SHF_MERGE
+    my $match;
+    if (length $self->strings && $self->strings =~ /($regex)/) {
+        $match = $1;
+
+    } elsif ($self->is_script) {
+        $match = $self->bytes_match($regex);
+    }
+
+    return $match // $EMPTY;
+}
+
+=item magic(COUNT)
+
+Returns the specified COUNT of magic bytes for the file.
+
+=cut
+
+sub magic {
+    my ($self, $count) = @_;
+
+    return $EMPTY
+      if length $self->link;
+
+    return $EMPTY
+      if $self->size < $count;
+
+    return $EMPTY
+      unless $self->is_open_ok;
+
+    my $magic;
+
+    open(my $fd, '<', $self->unpacked_path);
+    die encode_utf8($self->index->identifier
+          . ": Could not read $count bytes from "
+          . $self->name)
+      unless read($fd, $magic, $count) == $count;
+    close $fd;
+
+    return $magic;
+}
+
+=item C<hashbang>
+
+Returns the C<hashbang> for the file if it is a script.
+
+=cut
+
+has hashbang => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $EMPTY
+          unless $self->is_script;
+
+        my $trimmed_bytes = $EMPTY;
+        my $magic;
+
+        open(my $fd, '<', $self->unpacked_path);
+        if (read($fd, $magic, 2) && $magic eq $HASHBANG && !eof($fd)) {
+            $trimmed_bytes = <$fd>;
+        }
+        close $fd;
+
+        # decoding UTF-8 fails on magyarispell_1.6.1-2.dsc and ldc_1.24.0-1.dsc
+
+        # remove comment, if any
+        $trimmed_bytes =~ s/^([^#]*)/$1/;
+
+        # trim both ends
+        $trimmed_bytes =~ s/^\s+|\s+$//g;
+
+        return $trimmed_bytes;
+    }
+);
+
+=item interpreter_with_options
+
+Returns the interpreter requested by a script with options
+after stripping C<env>.
+
+=cut
+
+has interpreter_with_options => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $with_options = $self->hashbang;
+
+        $with_options =~ s{^/usr/bin/env\s+}{};
+
+        return $with_options;
+    }
+);
+
+=item interpreter
+
+Returns the interpreter requested by a script but strips C<env>.
+
+=cut
+
+has interpreter => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $interpreter = $self->interpreter_with_options;
+
+        # keep base command without options
+        $interpreter =~ s/^(\S+).*/$1/;
+
+        return $interpreter;
+    }
+);
+
+=item C<calls_env>
+
+Returns true if file is a script that calls C<env>.
+
+=cut
+
+has calls_env => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        # must return a boolean success value #943724
+        return 1
+          if $self->hashbang =~ m{^/usr/bin/env\s+};
+
+        return 0;
+    }
+);
+
+=item C<is_shell_script>
+
+Returns true if file is a script requesting a recognized shell
+interpreter.
+
+=cut
+
+has is_shell_script => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $interpreter = $self->interpreter;
+
+        # keep basename
+        my ($basename) = ($interpreter =~ m{([^/]*)/?$}s);
+
+        return 1
+          if $basename =~ /^(?:[bd]?a|t?c|(?:pd|m)?k|z)?sh$/;
+
+        return 0;
+    }
+);
+
+=item is_elf
+
+Returns true if file is an ELF executable, and false otherwise.
+
+=cut
+
+has is_elf => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return 1
+          if $self->magic($ELF_MAGIC_SIZE) eq "\x7FELF";
+
+        return 0;
+    }
+);
+
+=item is_script
+
+Returns true if file is a script and false otherwise.
+
+=cut
+
+has is_script => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        # skip lincity data files; magic: #!#!#!
+        return 0
+          if $self->magic($LINCITY_MAGIC_SIZE) eq '#!#!#!';
+
+        return 0
+          unless $self->magic($SHELL_SCRIPT_MAGIC_SIZE) eq $HASHBANG;
+
+        return 1;
+    }
+);
+
+=item is_maintainer_script
+
+Returns true if file is a maintainer script and false otherwise.
+
+=cut
+
+has is_maintainer_script => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return 1
+          if $self->name =~ /^ config | (?:pre|post)(?:inst|rm) $/x
+          && $self->is_open_ok;
+
+        return 0;
+    }
+);
+
+=item identity
+
+Returns the owner and group of the path, separated by a slash.
+
+NB: If only numerical owner information is available in the package,
+this may return a numerical owner (except uid 0 is always mapped to
+"root")
+
+=cut
+
+sub identity {
+    my ($self) = @_;
+
+    return $self->owner . $SLASH . $self->group;
+}
+
+=item operm
+
+Returns the file permissions of this object in octal (e.g. 0644).
+
+NB: This is only well defined for file entries that are subject to
+permissions (e.g. files).  Particularly, the value is not well defined
+for symlinks.
+
+=cut
+
+sub operm {
+    my ($self) = @_;
+
+    return $self->path_info & OPERM_MASK;
+}
+
+=item octal_permissions
+
+=cut
+
+sub octal_permissions {
+    my ($self) = @_;
+
+    return sprintf('%04o', $self->operm);
+}
+
+=item children
+
+Returns a list of children (as Lintian::File::Path objects) of this entry.
+The list and its contents should not be modified.
+
+Only returns direct children of this directory.  The entries are sorted by name.
+
+NB: Returns the empty list for non-dir entries.
+
+=cut
+
+sub children {
+    my ($self) = @_;
+
+    croak encode_utf8('No index in ' . $self->name)
+      unless defined $self->index;
+
+    my @names = values %{$self->childnames};
+
+    return map { $self->index->lookup($_) } @names;
+}
+
+=item descendants
+
+Returns a list of children (as Lintian::File::Path objects) of this entry.
+The list and its contents should not be modified.
+
+Descends recursively into subdirectories and return the descendants in
+breadth-first order.  Children of a given directory will be sorted by
+name.
+
+NB: Returns the empty list for non-dir entries.
+
+=cut
+
+sub descendants {
+    my ($self) = @_;
+
+    my @descendants = $self->children;
+
+    my @directories = grep { $_->is_dir } @descendants;
+    push(@descendants, $_->descendants) for @directories;
+
+    return @descendants;
+}
+
+=item timestamp
+
+Returns a Unix timestamp for the given path. This is a number of
+seconds since the start of Unix epoch in UTC.
+
+=cut
+
+sub timestamp {
+    my ($self) = @_;
+
+    my $timestamp = $self->date . $SPACE . $self->time;
+
+    return str2time($timestamp, 'GMT');
+}
+
+=item child(BASENAME)
+
+Returns the child named BASENAME if it is a child of this directory.
+Otherwise, this method returns C<undef>.
+
+Even for directories, BASENAME should not end with a slash.
+
+When invoked on non-dirs, this method always returns C<undef>.
+
+Example:
+
+  $dir_entry->child('foo') => $entry OR undef
+
+=cut
+
+sub child {
+    my ($self, $basename) = @_;
+
+    croak encode_utf8('No index in ' . $self->name)
+      unless defined $self->index;
+
+    croak encode_utf8($self->index->identifier . ': Basename is required')
+      unless length $basename;
+
+    my $childname = $self->childnames->{$basename};
+    return undef
+      unless $childname;
+
+    return $self->index->lookup($childname);
+}
+
+=item is_symlink
+
+Returns a truth value if this entry is a symlink.
+
+=item is_hardlink
+
+Returns a truth value if this entry is a hardlink to a regular file.
+
+NB: The target of a hardlink is always a regular file (and not a dir etc.).
+
+=item is_dir
+
+Returns a truth value if this entry is a dir.
+
+NB: Unlike the "-d $dir" operator this will never return true for
+symlinks, even if the symlink points to a dir.
+
+=item is_file
+
+Returns a truth value if this entry is a regular file (or a hardlink to one).
+
+NB: Unlike the "-f $file" operator this will never return true for
+symlinks, even if the symlink points to a file (or hardlink).
+
+=item is_regular_file
+
+Returns a truth value if this entry is a regular file.
+
+This is eqv. to $path->is_file and not $path->is_hardlink.
+
+NB: Unlike the "-f $file" operator this will never return true for
+symlinks, even if the symlink points to a file.
+
+=cut
+
+sub is_symlink {
+    my ($self) = @_;
+
+    return $self->path_info & TYPE_SYMLINK ? 1 : 0;
+}
+
+sub is_hardlink {
+    my ($self) = @_;
+
+    return $self->path_info & TYPE_HARDLINK ? 1 : 0;
+}
+
+sub is_dir {
+    my ($self) = @_;
+
+    return $self->path_info & TYPE_DIR ? 1 : 0;
+}
+
+sub is_file {
+    my ($self) = @_;
+
+    return $self->path_info & (TYPE_FILE | TYPE_HARDLINK) ? 1 : 0;
+}
+
+sub is_regular_file {
+    my ($self) = @_;
+
+    return $self->path_info & TYPE_FILE ? 1 : 0;
+}
+
+=item link_normalized
+
+Returns the target of the link normalized against it's directory name.
+If the link cannot be normalized or normalized path might escape the
+package root, this method returns C<undef>.
+
+NB: This method will return the empty string for links pointing to the
+root dir of the package.
+
+Only available on "links" (i.e. symlinks or hardlinks).  On non-links
+this will croak.
+
+I<Symlinks only>: If you want the symlink target as a L<Lintian::File::Path>
+object, use the L<resolve_path|/resolve_path([PATH])> method with no
+arguments instead.
+
+=cut
+
+has link_normalized => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $name = $self->name;
+        my $link = $self->link;
+
+        croak encode_utf8($self->index->identifier . ": $name is not a link")
+          unless length $link;
+
+        my $dir = $self->dirname;
+
+        # hardlinks are always relative to the package root
+        $dir = $SLASH
+          if $self->is_hardlink;
+
+        my $target = normalize_link_target($dir, $link);
+
+        return $target;
+    }
+);
+
+=item is_readable
+
+Returns a truth value if the permission bits of this entry have
+at least one bit denoting readability set (bitmask 0444).
+
+=item is_writable
+
+Returns a truth value if the permission bits of this entry have
+at least one bit denoting writability set (bitmask 0222).
+
+=item is_executable
+
+Returns a truth value if the permission bits of this entry have
+at least one bit denoting executability set (bitmask 0111).
+
+=cut
+
+sub is_readable   {
+    my ($self) = @_;
+
+    return $self->path_info & $READ_BITS;
+}
+
+sub is_writable   {
+    my ($self) = @_;
+
+    return $self->path_info & $WRITE_BITS;
+}
+
+sub is_executable {
+    my ($self) = @_;
+
+    return $self->path_info & $EXECUTABLE_BITS;
+}
+
+=item all_bits_set
+
+=cut
+
+sub all_bits_set {
+    my ($self, $bits) = @_;
+
+    return ($self->operm & $bits) == $bits;
+}
+
+=item is_setuid
+
+=cut
+
+sub is_setuid {
+    my ($self) = @_;
+
+    return $self->operm & $SETUID;
+}
+
+=item is_setgid
+
+=cut
+
+sub is_setgid {
+    my ($self) = @_;
+
+    return $self->operm & $SETGID;
+}
+
+=item unpacked_path
+
+Returns the path to this object on the file system, which must be a
+regular file, a hardlink or a directory.
+
+This method may fail if:
+
+=over 4
+
+=item * The object is neither a directory or a file-like object (e.g. a
+named pipe).
+
+=item * If the object is dangling symlink or the path traverses a symlink
+outside the package root.
+
+=back
+
+To test if this is safe to call, if the target is (supposed) to be a:
+
+=over 4
+
+=item * file or hardlink then test with L</is_open_ok>.
+
+=item * dir then assert L<resolve_path|/resolve_path([PATH])> returns a
+defined entry, for which L</is_dir> returns a truth value.
+
+=back
+
+=cut
+
+sub unpacked_path {
+    my ($self) = @_;
+
+    $self->_check_access;
+
+    croak encode_utf8('No index in ' . $self->name)
+      unless defined $self->index;
+
+    my $basedir = $self->index->basedir;
+
+    croak encode_utf8($self->index->identifier . ': No base directory')
+      unless length $basedir;
+
+    my $unpacked = path($basedir)->child($self->name)->stringify;
+
+    # bug in perl, file operator should not care but does
+    # https://github.com/Perl/perl5/issues/10550
+    # also, https://github.com/Perl/perl5/issues/9674
+    utf8::downgrade $unpacked;
+
+    return $unpacked;
+}
+
+=item is_open_ok
+
+Returns a truth value if it is safe to attempt open a read handle to
+the underlying file object.
+
+Returns a truth value if the path may be opened.
+
+=cut
+
+sub is_open_ok {
+    my ($self) = @_;
+
+    my $path_info = $self->path_info;
+
+    return 1
+      if ($path_info & OPEN_IS_OK) == OPEN_IS_OK;
+
+    return 0
+      if $path_info & ACCESS_INFO;
+
+    try {
+        $self->_check_open;
+
+    } catch {
+        return 0;
+
+        # perlcritic 1.140-1 requires the semicolon on the next line
+    };
+
+    return 1;
+}
+
+sub _check_access {
+    my ($self) = @_;
+
+    my $path_info = $self->path_info;
+
+    return 1
+      if ($path_info & FS_PATH_IS_OK) == FS_PATH_IS_OK;
+
+    return 0
+      if $path_info & ACCESS_INFO;
+
+    my $resolvable = $self->resolve_path;
+    unless ($resolvable) {
+        $self->path_info($self->path_info | UNSAFE_PATH);
+        # NB: We are deliberately vague here to avoid suggesting
+        # whether $path exists.  In some cases (e.g. lintian.d.o)
+        # the output is readily available to wider public.
+        confess encode_utf8($self->index->identifier
+              .': Attempt to access through broken or unsafe symlink: '
+              . $self->name);
+    }
+
+    $self->path_info($self->path_info | FS_PATH_IS_OK);
+
+    return 1;
+}
+
+sub _check_open {
+    my ($self) = @_;
+
+    $self->_check_access;
+
+    # Symlinks can point to a "non-file" object inside the
+    # package root
+    # Leave "_path_access" here as _check_access marks it either as
+    # "UNSAFE_PATH" or "FS_PATH_IS_OK"
+
+    confess encode_utf8($self->index->identifier
+          .': Opening of irregular file not supported: '
+          . $self->name)
+      unless $self->is_file || ($self->is_symlink && -e $self->unpacked_path);
+
+    $self->path_info($self->path_info | OPEN_IS_OK);
+
+    return 1;
+}
+
+=item follow
+
+Return dereferenced link if applicable
+
+=cut
+
+sub follow {
+    my ($self, $maxlinks) = @_;
+
+    return $self
+      unless length $self->link;
+
+    return $self->dereferenced
+      if defined $self->dereferenced;
+
+    # set limit
+    $maxlinks //= $MAXIMUM_LINK_DEPTH;
+
+    # catch recursive links
+    return undef
+      if $maxlinks <= 0;
+
+    # reduce counter
+    $maxlinks--;
+
+    my $reference;
+
+    croak encode_utf8('No index in ' . $self->name)
+      unless defined $self->index;
+
+    if ($self->is_hardlink) {
+        # hard links are resolved against package root
+        $reference = $self->index->lookup;
+
+    } else {
+        # otherwise resolve against the parent
+        $reference = $self->parent_dir;
+    }
+
+    croak encode_utf8($self->index->identifier
+          . ': No parent reference for link in '
+          . $self->name)
+      unless defined $reference;
+
+    # follow link
+    my $dereferenced = $reference->resolve_path($self->link, $maxlinks);
+    $self->dereferenced($dereferenced);
+
+    return $self->dereferenced;
+}
+
+=item resolve_path([PATH])
+
+Resolve PATH relative to this path entry.
+
+If PATH starts with a slash and the file hierarchy has a well-defined
+root directory, then PATH will instead be resolved relatively to the
+root dir.  If the file hierarchy does not have a well-defined root dir
+(e.g. for source packages), this method will return C<undef>.
+
+If PATH is omitted, then the entry is resolved and the target is
+returned if it is valid.  Except for symlinks, all entries always
+resolve to themselves.  NB: hardlinks also resolve as themselves.
+
+It is an error to attempt to resolve a PATH against a non-directory
+and non-symlink entry - as such resolution would always fail
+(i.e. foo/../bar is an invalid path unless foo is a directory or a
+symlink to a dir).
+
+
+The resolution takes symlinks into account and following them provided
+that the target path is valid (and can be followed safely).  If the
+path is invalid or circular (symlinks), escapes the root directory or
+follows an unsafe symlink, the method returns C<undef>.  Otherwise, it
+returns the path entry that denotes the target path.
+
+
+If PATH contains at least one path segment and ends with a slash, then
+the resolved path will end in a directory (or fail).  Otherwise, the
+resolved PATH can end in any entry I<except> a symlink.
+
+Examples:
+
+  $symlink_entry->resolve_path => $nonsymlink_entry OR undef
+
+  $x->resolve_path => $x
+
+  For directory or symlink entries (dol), you can also resolve a path:
+
+  $dol_entry->resolve_path('some/../where') => $nonsymlink_entry OR undef
+
+  # Note the trailing slash
+  $dol_entry->resolve_path('some/../where/') => $dir_entry OR undef
+
+=cut
+
+sub resolve_path {
+    my ($self, $request, $maxlinks) = @_;
+
+    croak encode_utf8('No index in ' . $self->name)
+      unless defined $self->index;
+
+    croak encode_utf8(
+        $self->index->identifier . ': Can only resolve string arguments')
+      if defined $request && ref($request) ne $EMPTY;
+
+    $request //= $EMPTY;
+
+    if (length $self->link) {
+        # follow the link
+        my $dereferenced = $self->follow($maxlinks);
+        return undef
+          unless defined $dereferenced;
+
+        # and use that to resolve the request
+        return $dereferenced->resolve_path($request, $maxlinks);
+    }
+
+    my $reference;
+
+    # check for absolute reference; remove slash
+    if ($request =~ s{^/+}{}s) {
+
+        # require anchoring for absolute references
+        return undef
+          unless $self->index->anchored;
+
+        # get root entry
+        $reference = $self->index->lookup;
+
+    } elsif ($self->is_dir) {
+        # directories are their own starting point
+        $reference = $self;
+
+    } else {
+        # otherwise, use parent directory
+        $reference = $self->parent_dir;
+    }
+
+    return undef
+      unless defined $reference;
+
+    # read first segment; strip all trailing slashes for recursive use
+    if ($request =~ s{^([^/]+)/*}{}) {
+
+        my $segment = $1;
+
+        # single dot, or two slashes in a row
+        return $reference->resolve_path($request, $maxlinks)
+          if $segment eq $DOT || !length $segment;
+
+        # for double dot, go up a level
+        if ($segment eq $DOUBLE_DOT) {
+            my $parent = $reference->parent_dir;
+            return undef
+              unless defined $parent;
+
+            return $parent->resolve_path($request, $maxlinks);
+        }
+
+        # look for child otherwise
+        my $child = $reference->child($segment);
+        return undef
+          unless defined $child;
+
+        return $child->resolve_path($request, $maxlinks);
+    }
+
+    croak encode_utf8($self->index->identifier
+          . ": Cannot parse path resolution request: $request")
+      if length $request;
+
+    # nothing else to resolve
+    return $self;
+}
+
+=item name
+
+Returns the name of the file (relative to the package root).
+
+NB: It will never have any leading "./" (or "/") in it.
+
+=item basename
+
+Returns the "filename" part of the name, similar basename(1) or
+File::Basename::basename (without passing a suffix to strip in either
+case).
+
+NB: Returns the empty string for the "root" dir.
+
+=item dirname
+
+Returns the "directory" part of the name, similar to dirname(1) or
+File::Basename::dirname.  The dirname will end with a trailing slash
+(except the "root" dir - see below).
+
+NB: Returns the empty string for the "root" dir.
+
+=item link
+
+If this is a link (i.e. is_symlink or is_hardlink returns a truth
+value), this method returns the target of the link.
+
+If this is not a link, then this returns undef.
+
+If the path is a symlink this method can be used to determine if the
+symlink is relative or absolute.  This is I<not> true for hardlinks,
+where the link target is always relative to the root.
+
+NB: Even for symlinks, a leading "./" will be stripped.
+
+=item normalized
+
+=item faux
+
+Returns a truth value if this entry absent in the package.  This can
+happen if a package does not include all intermediate directories.
+
+=item size
+
+Returns the size of the path in bytes.
+
+NB: Only regular files can have a non-zero file size.
+
+=item date
+
+Return the modification date as YYYY-MM-DD.
+
+=item time
+
+=item perm
+
+=item path_info
+
+=item owner
+
+Returns the owner of the path entry as a username.
+
+NB: If only numerical owner information is available in the package,
+this may return a numerical owner (except uid 0 is always mapped to
+"root")
+
+=item group
+
+Returns the group of the path entry as a username.
+
+NB: If only numerical owner information is available in the package,
+this may return a numerical group (except gid 0 is always mapped to
+"root")
+
+=item uid
+
+Returns the uid of the owner of the path entry.
+
+NB: If the uid is not available, 0 will be returned.
+This usually happens if the numerical data is not collected (e.g. in
+source packages)
+
+=item gid
+
+Returns the gid of the owner of the path entry.
+
+NB: If the gid is not available, 0 will be returned.
+This usually happens if the numerical data is not collected (e.g. in
+source packages)
+
+=item file_type
+
+Return the data from L<file(1)> if it has been collected.
+
+Note this is only defined for files as Lintian only runs L<file(1)> on
+files.
+
+=item java_info
+
+=item strings
+
+=item C<basedir>
+
+=item index
+
+=item parent_dir
+
+=item child_table
+
+=item sorted_children
+
+Returns the parent directory entry of this entry as a
+L<Lintian::File::Path>.
+
+NB: Returns C<undef> for the "root" dir.
+
+=item C<childnames>
+
+=item parent_dir
+
+Return the parent dir entry of this the path entry.
+
+=item dereferenced
+
+=cut
+
+has name => (
+    is => 'rw',
+    lazy => 1,
+    coerce => sub { my ($string) = @_; return $string // $EMPTY;},
+    trigger => sub {
+        my ($self, $name) = @_;
+
+        my ($basename) = ($name =~ m{([^/]*)/?$}s);
+        $self->basename($basename);
+
+        # allow newline in names; need /s for dot matching (#929729)
+        my ($dirname) = ($name =~ m{^(.+/)?(?:[^/]+/?)$}s);
+        $self->dirname($dirname);
+    },
+    default => $EMPTY
+);
+has basename => (
+    is => 'rw',
+    lazy => 1,
+    coerce => sub { my ($string) = @_; return $string // $EMPTY;},
+    default => $EMPTY
+);
+has dirname => (
+    is => 'rw',
+    lazy => 1,
+    coerce => sub { my ($string) = @_; return $string // $EMPTY;},
+    default => $EMPTY
+);
+
+has link => (
+    is => 'rw',
+    coerce => sub { my ($string) = @_; return $string // $EMPTY;},
+    default => $EMPTY
+);
+has normalized => (
+    is => 'rw',
+    coerce => sub { my ($string) = @_; return $string // $EMPTY;},
+    default => $EMPTY
+);
+has faux => (is => 'rw', default => 0);
+
+has size => (is => 'rw', default => 0);
+has date => (
+    is => 'rw',
+    default => sub {
+        my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = gmtime;
+        return sprintf('%04d-%02d-%02d', $year, $mon, $mday);
+    }
+);
+has time => (
+    is => 'rw',
+    default => sub {
+        my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = gmtime;
+        return sprintf('%02d:%02d:%02d', $hour, $min, $sec);
+    }
+);
+
+has perm => (is => 'rw');
+has path_info => (is => 'rw');
+
+has owner => (
+    is => 'rw',
+    coerce => sub { my ($string) = @_; return $string // 'root'; },
+    default => 'root'
+);
+has group => (
+    is => 'rw',
+    coerce => sub { my ($string) = @_; return $string // 'root'; },
+    default => 'root'
+);
+has uid => (
+    is => 'rw',
+    coerce => sub { my ($value) = @_; return int($value // 0); },
+    default => 0
+);
+has gid => (
+    is => 'rw',
+    coerce => sub { my ($value) = @_; return int($value // 0); },
+    default => 0
+);
+
+has md5sum => (
+    is => 'rw',
+    coerce => sub { my ($checksum) = @_; return ($checksum // 0); },
+    default => 0
+);
+has file_type => (
+    is => 'rw',
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); },
+    default => $EMPTY
+);
+has java_info => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+has strings => (
+    is => 'rw',
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); },
+    default => $EMPTY
+);
+has ar_info => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+has index => (is => 'rw');
+has childnames => (is => 'rw', default => sub { {} });
+has parent_dir => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        # do not return root as its own parent
+        return
+          if $self->name eq $EMPTY;
+
+        croak encode_utf8('No index in ' . $self->name)
+          unless defined $self->index;
+
+        # returns root by default
+        return $self->index->lookup($self->dirname);
+    }
+);
+has dereferenced => (is => 'rw');
+
+=item elf
+
+=cut
+
+sub elf {
+    my ($self, @args) = @_;
+
+    if (@args) {
+
+        $self->index->elf_storage->{$self->name} = $args[0];
+
+        return ();
+    }
+
+    my %copy = %{$self->index->elf_storage->{$self->name} // {} };
+
+    return \%copy;
+}
+
+=item elf_by_member
+
+=cut
+
+sub elf_by_member {
+    my ($self, @args) = @_;
+
+    if (@args) {
+
+        my $object_name = $args[0];
+        my $by_object = $args[1];
+
+        my $tmp = $self->index->elf_storage_by_member->{$self->name} // {};
+        $tmp->{$object_name} = $by_object;
+        $self->index->elf_storage_by_member->{$self->name} = $tmp;
+
+        return ();
+    }
+
+    my %copy = %{$self->index->elf_storage_by_member->{$self->name} // {} };
+
+    return \%copy;
+}
+
+=item pointer
+
+=cut
+
+sub pointer {
+    my ($self, $position) = @_;
+
+    my $pointer = Lintian::Pointer::Item->new;
+    $pointer->item($self);
+    $pointer->position($position);
+
+    return $pointer;
+}
+
+=item bytes
+
+Returns verbatim file contents as a scalar.
+
+=item is_valid_utf8
+
+Boolean true if file contents are valid UTF-8.
+
+=item decoded_utf8
+
+Returns a decoded, wide-character string if file contents are valid UTF-8.
+
+=cut
+
+sub bytes {
+    my ($self) = @_;
+
+    return $EMPTY
+      unless $self->is_open_ok;
+
+    my $bytes = path($self->unpacked_path)->slurp;
+
+    return $bytes;
+}
+
+sub is_valid_utf8 {
+    my ($self) = @_;
+
+    my $bytes = $self->bytes;
+    return 0
+      unless defined $bytes;
+
+    return valid_utf8($bytes);
+}
+
+sub decoded_utf8 {
+    my ($self) = @_;
+
+    return $EMPTY
+      unless $self->is_valid_utf8;
+
+    return decode_utf8($self->bytes);
+}
+
+### OVERLOADED OPERATORS ###
+
+# overload apparently does not like the mk_ro_accessor, so use a level
+# of indirection
+
+sub _as_regex_ref {
+    my ($self) = @_;
+    my $name = $self->name;
+    return qr{ \Q$name\E }xsm;
+}
+
+sub _as_string {
+    my ($self) = @_;
+    return $self->name;
+}
+
+sub _bool {
+    # Always true (used in "if ($info->index('some/path')) {...}")
+    return 1;
+}
+
+sub _bool_not {
+    my ($self) = @_;
+    return !$self->_bool;
+}
+
+sub _str_cmp {
+    my ($self, $str, $swap) = @_;
+    return $str cmp $self->name if $swap;
+    return $self->name cmp $str;
+}
+
+sub _str_concat {
+    my ($self, $str, $swap) = @_;
+    return $str . $self->name if $swap;
+    return $self->name . $str;
+}
+
+sub _str_eq {
+    my ($self, $str) = @_;
+    return $self->name eq $str;
+}
+
+sub _str_ne {
+    my ($self, $str) = @_;
+    return $self->name ne $str;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Niels Thykier <niels@thykier.net> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
+
diff --git a/lib/Lintian/Index/Java.pm b/lib/Lintian/Index/Java.pm
new file mode 100644
index 0000000..4b33bec
--- /dev/null
+++ b/lib/Lintian/Index/Java.pm
@@ -0,0 +1,258 @@
+# -*- perl -*- Lintian::Index::Java
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Index::Java;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Archive::Zip qw( :ERROR_CODES :CONSTANTS );
+use Const::Fast;
+use Cwd;
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo::Role;
+use namespace::clean;
+
+const my $EMPTY => q{};
+const my $NEWLINE => qq{\n};
+const my $SPACE => q{ };
+const my $DASH => q{-};
+
+const my $JAVA_MAGIC_SIZE => 8;
+const my $JAVA_MAGIC_BYTES => 0xCAFEBABE;
+
+=head1 NAME
+
+Lintian::Index::Java - java information.
+
+=head1 SYNOPSIS
+
+    use Lintian::Index;
+
+=head1 DESCRIPTION
+
+Lintian::Index::Java java information.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item add_java
+
+=cut
+
+sub add_java {
+    my ($self) = @_;
+
+    my $savedir = getcwd;
+    chdir($self->basedir)
+      or die encode_utf8(
+        $self->identifier . ': Cannot change to directory ' . $self->basedir);
+
+    my $errors = $EMPTY;
+
+    my @files = grep { $_->is_file } @{$self->sorted_list};
+
+    # Wheezy's version of file calls "jar files" for "Zip archive".
+    # Newer versions seem to call them "Java Jar file".
+    # Jessie also introduced "Java archive data (JAR)"...
+    my @java_files = grep {
+        $_->file_type=~ m{
+            Java [ ] (?:Jar [ ] file|archive [ ] data)
+            | Zip [ ] archive
+            | JAR }x;
+    } @files;
+
+    my @lines;
+    for my $file (@java_files) {
+
+        push(@lines, parse_jar($file->name))
+          if $file->name =~ /\S+\.jar$/i;
+    }
+
+    my $file;
+    my $file_list;
+    my $manifest = 0;
+    local $_ = undef;
+
+    my %java_info;
+
+    for my $line (@lines) {
+        chomp $line;
+        next if $line =~ /^\s*$/;
+
+        if ($line =~ /^-- ERROR:\s*(\S.+)$/) {
+            $java_info{$file}{error} = $1;
+
+        } elsif ($line =~ m{^-- MANIFEST: (?:\./)?(?:.+)$}) {
+            # TODO: check $file == $1 ?
+            $java_info{$file}{manifest} = {};
+            $manifest = $java_info{$file}{manifest};
+            $file_list = 0;
+
+        } elsif ($line =~ m{^-- (?:\./)?(.+)$}) {
+            $file = $1;
+            $java_info{$file}{files} = {};
+            $file_list = $java_info{$file}{files};
+            $manifest = 0;
+        } else {
+            if ($manifest && $line =~ m{^  (\S+):\s(.*)$}) {
+                $manifest->{$1} = $2;
+            } elsif ($file_list) {
+                my ($fname, $clmajor) = ($line =~ m{^([^-].*):\s*([-\d]+)$});
+                $file_list->{$fname} = $clmajor;
+            }
+        }
+    }
+
+    $_->java_info($java_info{$_->name}) for @java_files;
+
+    chdir($savedir)
+      or die encode_utf8(
+        $self->identifier . ": Cannot change to directory $savedir");
+
+    return $errors;
+}
+
+=item parse_jar
+
+=cut
+
+sub parse_jar {
+    my ($path) = @_;
+
+    my @lines;
+
+    # This script needs unzip, there's no way around.
+    push(@lines, "-- $path");
+
+    # Without this Archive::Zip will emit errors to standard error for
+    # faulty zip files - but that is not what we want.  AFAICT, it is
+    # the only way to get a textual error as well, so (ab)use it for
+    # this purpose while we are at it.
+    my $errorhandler = sub {
+        my ($err) = @_;
+        $err =~ s/\r?\n/ /g;
+
+        # trim right
+        $err =~ s/\s+$//;
+
+        push(@lines, "-- ERROR: $err");
+    };
+    my $oldhandler = Archive::Zip::setErrorHandler($errorhandler);
+
+    my $azip = Archive::Zip->new;
+    if($azip->read($path) == AZ_OK) {
+
+        # save manifest for the end
+        my $manifest;
+
+        # file list comes first
+        foreach my $member ($azip->members) {
+            my $name = $member->fileName;
+
+            next
+              if $member->isDirectory;
+
+            # store for later processing
+            $manifest = $member
+              if $name =~ m{^META-INF/MANIFEST.MF$}i;
+
+            # add version if we can find it
+            my $jversion;
+            if ($name =~ /\.class$/) {
+                # Collect the Major version of the class file.
+                my ($contents, $zerr) = $member->contents;
+
+       # bug in Archive::Zip; seen in android-platform-libcore_10.0.0+r36-1.dsc
+                last
+                  unless defined $zerr;
+
+                last
+                  unless $zerr == AZ_OK;
+
+                # Ensure we can read at least 8 bytes for the unpack.
+                next
+                  if length $contents < $JAVA_MAGIC_SIZE;
+
+                # translation of the unpack
+                #  NN NN NN NN, nn nn, nn nn   - bytes read
+                #     $magic  , __ __, $major  - variables
+                my ($magic, undef, $major) = unpack('Nnn', $contents);
+                $jversion = $major
+                  if $magic == $JAVA_MAGIC_BYTES;
+            }
+            push(@lines, "$name: " . ($jversion // $DASH));
+        }
+
+        if ($manifest) {
+            push(@lines, "-- MANIFEST: $path");
+
+            my ($contents, $zerr) = $manifest->contents;
+
+       # bug in Archive::Zip; seen in android-platform-libcore_10.0.0+r36-1.dsc
+            return ()
+              unless defined $zerr;
+
+            if ($zerr == AZ_OK) {
+                my $partial = $EMPTY;
+                my $first = 1;
+                my @list = split($NEWLINE, $contents);
+                foreach my $line (@list) {
+
+                    # remove DOS type line feeds
+                    $line =~ s/\r//g;
+
+                    if ($line =~ /^(\S+:)\s*(.*)/) {
+                        push(@lines, $SPACE . $SPACE . "$1 $2");
+                    }
+                    if ($line =~ /^ (.*)/) {
+                        push(@lines, $1);
+                    }
+                }
+            }
+        }
+    }
+
+    Archive::Zip::setErrorHandler($oldhandler);
+
+    return @lines;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Index/Md5sums.pm b/lib/Lintian/Index/Md5sums.pm
new file mode 100644
index 0000000..c1d0583
--- /dev/null
+++ b/lib/Lintian/Index/Md5sums.pm
@@ -0,0 +1,127 @@
+# -*- perl -*- Lintian::Index::Md5sums
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Index::Md5sums;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Cwd;
+use Unicode::UTF8 qw(encode_utf8 decode_utf8);
+
+use Lintian::IPC::Run3 qw(xargs);
+use Lintian::Util qw(read_md5sums);
+
+use Moo::Role;
+use namespace::clean;
+
+const my $EMPTY => q{};
+const my $NEWLINE => qq{\n};
+
+const my $WAIT_STATUS_SHIFT => 8;
+const my $NULL => qq{\0};
+
+=head1 NAME
+
+Lintian::Index::Md5sums - calculate checksums for index.
+
+=head1 SYNOPSIS
+
+    use Lintian::Index;
+
+=head1 DESCRIPTION
+
+Lintian::Index::Md5sums calculates checksums for an index.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item add_md5sums
+
+=cut
+
+sub add_md5sums {
+    my ($self) = @_;
+
+    my $savedir = getcwd;
+    chdir($self->basedir)
+      or die encode_utf8(
+        $self->identifier . ': Cannot change to directory ' . $self->basedir);
+
+    my $errors = $EMPTY;
+
+    # get the regular files in the index
+    my @files = grep { $_->is_file } @{$self->sorted_list};
+    my @names = map { $_->name } @files;
+
+    my @command = qw(md5sum --);
+
+    my %md5sums;
+
+    xargs(
+        \@command,
+        \@names,
+        sub {
+            my ($stdout, $stderr, $status, @partial) = @_;
+
+            $stderr = decode_utf8($stderr)
+              if length $stderr;
+
+            if ($status) {
+                $errors .= "Cannot run @command: $stderr" . $NEWLINE;
+                return;
+            }
+
+            # undecoded split allows names with non UTF-8 bytes
+            my ($partial_sums, undef) = read_md5sums($stdout);
+
+            $md5sums{$_} = $partial_sums->{$_}for @partial;
+        }
+    );
+
+    $_->md5sum($md5sums{$_->name}) for @files;
+
+    chdir($savedir)
+      or die encode_utf8(
+        $self->identifier . ": Cannot change to directory $savedir");
+
+    return $errors;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Index/Strings.pm b/lib/Lintian/Index/Strings.pm
new file mode 100644
index 0000000..f0e4fa1
--- /dev/null
+++ b/lib/Lintian/Index/Strings.pm
@@ -0,0 +1,99 @@
+# -*- perl -*- Lintian::Index::Strings
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Index::Strings;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Path::Tiny;
+use Unicode::UTF8 qw(decode_utf8);
+
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Moo::Role;
+use namespace::clean;
+
+const my $EMPTY => q{};
+
+=head1 NAME
+
+Lintian::Index::Strings - strings in binary files.
+
+=head1 SYNOPSIS
+
+    use Lintian::Index;
+
+=head1 DESCRIPTION
+
+Lintian::Index::Strings strings in binary files.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item add_strings
+
+=cut
+
+sub add_strings {
+    my ($self) = @_;
+
+    my $errors = $EMPTY;
+
+    my @files = grep { $_->is_file } @{$self->sorted_list};
+    for my $file (@files) {
+
+        next
+          if $file->name =~ m{^usr/lib/debug/};
+
+        # skip non-binaries
+        next
+          unless $file->file_type =~ /\bELF\b/;
+
+        # prior implementations sometimes made the list unique
+        my $allstrings
+          = decode_utf8(safe_qx(qw{strings --all --}, $file->unpacked_path));
+
+        $file->strings($allstrings);
+    }
+
+    return $errors;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Mask.pm b/lib/Lintian/Mask.pm
new file mode 100644
index 0000000..475e65c
--- /dev/null
+++ b/lib/Lintian/Mask.pm
@@ -0,0 +1,76 @@
+# -*- perl -*- Lintian::Mask
+#
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Mask;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $EMPTY => q{};
+
+use Moo;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Mask - access to mask data
+
+=head1 SYNOPSIS
+
+    use Lintian::Mask;
+
+=head1 DESCRIPTION
+
+Lintian::Mask provides access to mask data.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item screen
+
+=item excuse
+
+=cut
+
+has screen => (is => 'rw', default => $EMPTY);
+
+has excuse => (is => 'rw', default => $EMPTY);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Output/EWI.pm b/lib/Lintian/Output/EWI.pm
new file mode 100644
index 0000000..af0fac6
--- /dev/null
+++ b/lib/Lintian/Output/EWI.pm
@@ -0,0 +1,614 @@
+# Copyright (C) 2008 Frank Lichtenheld <frank@lichtenheld.de>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Output::EWI;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use HTML::HTML5::Entities;
+use List::Compare;
+use Term::ANSIColor ();
+use Text::Wrap;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Output::Markdown qw(markdown_citation);
+
+# for tty hyperlinks
+const my $OSC_HYPERLINK => qq{\033]8;;};
+const my $OSC_DONE => qq{\033\\};
+const my $BEL => qq{\a};
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $COLON => q{:};
+const my $DOT => q{.};
+const my $NEWLINE => qq{\n};
+const my $PARAGRAPH_BREAK => $NEWLINE x 2;
+
+const my $YES => q{yes};
+const my $NO => q{no};
+
+const my $COMMENT_PREFIX => q{N:} . $SPACE;
+
+const my $DESCRIPTION_INDENTATION => 2;
+const my $DESCRIPTION_PREFIX => $COMMENT_PREFIX
+  . $SPACE x $DESCRIPTION_INDENTATION;
+
+const my $SCREEN_INDENTATION => 4;
+const my $SCREEN_PREFIX => $COMMENT_PREFIX . $SPACE x $SCREEN_INDENTATION;
+
+const my %COLORS => (
+    'E' => 'bright_white on_bright_red',
+    'W' => 'black on_bright_yellow',
+    'I' => 'bright_white on_bright_blue',
+    'P' => 'bright_white on_green',
+    'C' => 'bright_white on_bright_magenta',
+    'X' => 'bright_white on_yellow',
+    'O' => 'bright_white on_bright_black',
+    'M' => 'bright_black on_bright_white',
+);
+
+const my %CODE_PRIORITY => (
+    'E' => 30,
+    'W' => 40,
+    'I' => 50,
+    'P' => 60,
+    'X' => 70,
+    'C' => 80,
+    'O' => 90,
+    'M' => 100,
+);
+
+const my %TYPE_PRIORITY => (
+    'source' => 30,
+    'binary' => 40,
+    'udeb' => 50,
+    'changes' => 60,
+    'buildinfo' => 70,
+);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Output::Grammar';
+
+=head1 NAME
+
+Lintian::Output::EWI - standard hint output
+
+=head1 SYNOPSIS
+
+    use Lintian::Output::EWI;
+
+=head1 DESCRIPTION
+
+Provides standard hint output.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item tag_count_by_processable
+
+=cut
+
+has tag_count_by_processable => (is => 'rw', default => sub { {} });
+
+=item issue_hints
+
+=cut
+
+sub issue_hints {
+    my ($self, $profile, $groups, $option) = @_;
+
+    my %sorter;
+    for my $group (@{$groups // []}) {
+
+        for my $processable ($group->get_processables) {
+
+            my $type = $processable->type;
+            my $type_priority = $TYPE_PRIORITY{$type};
+
+            for my $hint (@{$processable->hints}) {
+
+                my $tag = $profile->get_tag($hint->tag_name);
+
+                my $override_status = 0;
+                $override_status = 1
+                  if defined $hint->override || @{$hint->masks};
+
+                my $ranking_code = $tag->code;
+                $ranking_code = 'X'
+                  if $tag->experimental;
+                $ranking_code = 'O'
+                  if defined $hint->override;
+                $ranking_code = 'M'
+                  if @{$hint->masks};
+
+                my $code_priority = $CODE_PRIORITY{$ranking_code};
+
+                my %for_output;
+                $for_output{hint} = $hint;
+                $for_output{processable} = $processable;
+
+                push(
+                    @{
+                        $sorter{$override_status}{$code_priority}{$tag->name}
+                          {$type_priority}{$processable->name}{$hint->context}
+                    },
+                    \%for_output
+                );
+            }
+        }
+    }
+
+    for my $override_status (sort keys %sorter) {
+
+        my %by_code_priority = %{$sorter{$override_status}};
+
+        for my $code_priority (sort { $a <=> $b } keys %by_code_priority) {
+
+            my %by_tag_name = %{$by_code_priority{$code_priority}};
+
+            for my $tag_name (sort keys %by_tag_name) {
+
+                my %by_type_priority = %{$by_tag_name{$tag_name}};
+
+                for
+                  my $type_priority (sort { $a <=> $b }keys %by_type_priority){
+
+                    my %by_processable_name
+                      = %{$by_type_priority{$type_priority}};
+
+                    for my $processable_name (sort keys %by_processable_name) {
+
+                        my %by_context
+                          = %{$by_processable_name{$processable_name}};
+
+                        for my $context (sort keys %by_context) {
+
+                            my $for_output
+                              = $sorter{$override_status}{$code_priority}
+                              {$tag_name}{$type_priority}{$processable_name}
+                              {$context};
+
+                            for my $each (@{$for_output}) {
+
+                                my $hint = $each->{hint};
+                                my $processable = $each->{processable};
+
+                                $self->print_hint($profile, $hint,
+                                    $processable,$option)
+                                  if ( !defined $hint->override
+                                    && !@{$hint->masks})
+                                  || $option->{'show-overrides'};
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    return;
+}
+
+=item C<print_hint>
+
+=cut
+
+sub print_hint {
+    my ($self, $profile, $hint, $processable, $option) = @_;
+
+    my $tag_name = $hint->tag_name;
+    my $tag = $profile->get_tag($tag_name);
+
+    my @want_references = @{$option->{'display-source'} // []};
+    my @have_references = @{$tag->see_also};
+
+    # keep only the first word
+    s{^ ([\w-]+) \s }{$1}x for @have_references;
+
+    # drop anything in parentheses at the end
+    s{ [(] \S+ [)] $}{}x for @have_references;
+
+    # check if hint refers to the selected references
+    my $reference_lc= List::Compare->new(\@have_references, \@want_references);
+
+    my @found_references = $reference_lc->get_intersection;
+
+    return
+      if @want_references
+      && !@found_references;
+
+    my $information = $hint->context;
+    $information = $SPACE . $self->_quote_print($information)
+      unless $information eq $EMPTY;
+
+    # Limit the output so people do not drown in hints.  Some hints are
+    # insanely noisy (hi static-library-has-unneeded-section)
+    my $limit = $option->{'tag-display-limit'};
+    if ($limit) {
+
+        my $processable_id = $processable->identifier;
+        my $emitted_count
+          = $self->tag_count_by_processable->{$processable_id}{$tag_name}++;
+
+        return
+          if $emitted_count >= $limit;
+
+        my $msg
+          = ' ... use "--tag-display-limit 0" to see all (or pipe to a file/program)';
+        $information = $self->_quote_print($msg)
+          if $emitted_count >= $limit-1;
+    }
+
+    say encode_utf8('N:')
+      if $option->{info};
+
+    my $text = $tag_name;
+
+    my $code = $tag->code;
+    $code = 'X' if $tag->experimental;
+    $code = 'O' if defined $hint->override;
+    $code = 'M' if @{$hint->masks};
+
+    my $tag_color = $COLORS{$code};
+
+    $text = Term::ANSIColor::colored($tag_name, $tag_color)
+      if $option->{color};
+
+    my $output;
+    if ($option->{hyperlinks} && $option->{color}) {
+        my $target= 'https://lintian.debian.org/tags/' . $tag_name;
+        $output .= $self->osc_hyperlink($text, $target);
+    } else {
+        $output .= $text;
+    }
+
+    local $Text::Wrap::columns
+      = $option->{'output-width'} - length $COMMENT_PREFIX;
+
+    # do not wrap long words such as urls; see #719769
+    local $Text::Wrap::huge = 'overflow';
+
+    if ($hint->override && length $hint->override->justification) {
+
+        my $wrapped = wrap($COMMENT_PREFIX, $COMMENT_PREFIX,
+            $hint->override->justification);
+        say encode_utf8($wrapped);
+    }
+
+    for my $mask (@{$hint->masks}) {
+
+        say encode_utf8($COMMENT_PREFIX . 'masked by screen ' . $mask->screen);
+
+        next
+          unless length $mask->excuse;
+
+        my $wrapped= wrap($COMMENT_PREFIX, $COMMENT_PREFIX, $mask->excuse);
+        say encode_utf8($wrapped);
+    }
+
+    my $type = $EMPTY;
+    $type = $SPACE . $processable->type
+      unless $processable->type eq 'binary';
+
+    say encode_utf8($code
+          . $COLON
+          . $SPACE
+          . $processable->name
+          . $type
+          . $COLON
+          . $SPACE
+          . $output
+          . $information);
+
+    if ($option->{info}) {
+
+        # show only on first issuance
+        $self->describe_tag($profile->data, $tag, $option->{'output-width'})
+          unless $self->issued_tag($tag->name);
+    }
+
+    return;
+}
+
+=item C<_quote_print($string)>
+
+Called to quote a string.  By default it will replace all
+non-printables with "?".  Sub-classes can override it if
+they allow non-ascii printables etc.
+
+=cut
+
+sub _quote_print {
+    my ($self, $string) = @_;
+
+    $string =~ s/[^[:print:]]/?/g;
+
+    return $string;
+}
+
+=item C<osc_hyperlink>
+
+=cut
+
+sub osc_hyperlink {
+    my ($self, $text, $target) = @_;
+
+    my $start = $OSC_HYPERLINK . $target . $BEL;
+    my $end = $OSC_HYPERLINK . $BEL;
+
+    return $start . $text . $end;
+}
+
+=item issuedtags
+
+Hash containing the names of tags which have been issued.
+
+=cut
+
+has issuedtags => (is => 'rw', default => sub { {} });
+
+=item C<issued_tag($tag_name)>
+
+Indicate that the named tag has been issued.  Returns a boolean value
+indicating whether the tag had previously been issued by the object.
+
+=cut
+
+sub issued_tag {
+    my ($self, $tag_name) = @_;
+
+    return $self->issuedtags->{$tag_name}++ ? 1 : 0;
+}
+
+=item describe_tags
+
+=cut
+
+sub describe_tags {
+    my ($self, $data, $tags, $columns) = @_;
+
+    for my $tag (@{$tags}) {
+
+        my $name;
+        my $code;
+
+        if (defined $tag) {
+            $name = $tag->name;
+            $code = $tag->code;
+
+        } else {
+            $name = 'unknown-tag';
+            $code = 'N';
+        }
+
+        say encode_utf8('N:');
+        say encode_utf8("$code: $name");
+
+        $self->describe_tag($data, $tag, $columns);
+    }
+
+    return;
+}
+
+=item describe_tag
+
+=cut
+
+sub describe_tag {
+    my ($self, $data, $tag, $columns) = @_;
+
+    local $Text::Wrap::columns = $columns;
+
+    # do not wrap long words such as urls; see #719769
+    local $Text::Wrap::huge = 'overflow';
+
+    my $wrapped = $COMMENT_PREFIX . $NEWLINE;
+
+    if (defined $tag) {
+
+        my $plain_explanation = markdown_to_plain($tag->explanation,
+            $columns - length $DESCRIPTION_PREFIX);
+
+        $wrapped .= $DESCRIPTION_PREFIX . $_ . $NEWLINE
+          for split(/\n/, $plain_explanation);
+
+        if (@{$tag->see_also}) {
+
+            $wrapped .= $COMMENT_PREFIX . $NEWLINE;
+
+            my @see_also_markdown
+              = map { markdown_citation($data, $_) } @{$tag->see_also};
+            my $markdown
+              = 'Please refer to '
+              . $self->oxford_enumeration('and', @see_also_markdown)
+              . ' for details.'
+              . $NEWLINE;
+            my $plain = markdown_to_plain($markdown,
+                $columns - length $DESCRIPTION_PREFIX);
+
+            $wrapped .= $DESCRIPTION_PREFIX . $_ . $NEWLINE
+              for split(/\n/, $plain);
+        }
+
+        $wrapped .= $COMMENT_PREFIX . $NEWLINE;
+
+        my $visibility_prefix = 'Visibility: ';
+        $wrapped.= wrap(
+            $DESCRIPTION_PREFIX . $visibility_prefix,
+            $DESCRIPTION_PREFIX . $SPACE x length $visibility_prefix,
+            $tag->visibility . $NEWLINE
+        );
+
+        $wrapped .= wrap($DESCRIPTION_PREFIX, $DESCRIPTION_PREFIX,
+            'Show-Always: '. ($tag->show_always ? $YES : $NO) . $NEWLINE);
+
+        my $check_prefix = 'Check: ';
+        $wrapped .= wrap(
+            $DESCRIPTION_PREFIX . $check_prefix,
+            $DESCRIPTION_PREFIX . $SPACE x length $check_prefix,
+            $tag->check . $NEWLINE
+        );
+
+        if (@{$tag->renamed_from}) {
+
+            $wrapped .= wrap($DESCRIPTION_PREFIX, $DESCRIPTION_PREFIX,
+                'Renamed from: '
+                  . join($SPACE, @{$tag->renamed_from})
+                  . $NEWLINE);
+        }
+
+        $wrapped
+          .= wrap($DESCRIPTION_PREFIX, $DESCRIPTION_PREFIX,
+            'This tag is experimental.' . $NEWLINE)
+          if $tag->experimental;
+
+        $wrapped .= wrap($DESCRIPTION_PREFIX, $DESCRIPTION_PREFIX,
+            'This tag is a classification. There is no issue in your package.'
+              . $NEWLINE)
+          if $tag->visibility eq 'classification';
+
+        for my $screen (@{$tag->screens}) {
+
+            $wrapped .= $COMMENT_PREFIX . $NEWLINE;
+
+            $wrapped
+              .= wrap($DESCRIPTION_PREFIX, $DESCRIPTION_PREFIX,
+                'Screen: ' . $screen->name . $NEWLINE);
+
+            $wrapped .= wrap($SCREEN_PREFIX, $SCREEN_PREFIX,
+                'Advocates: '. join(', ', @{$screen->advocates}). $NEWLINE);
+
+            my $combined = $screen->reason . $NEWLINE;
+            if (@{$screen->see_also}) {
+
+                $combined .= $NEWLINE;
+
+                my @see_also_markdown
+                  = map { markdown_citation($data, $_) } @{$screen->see_also};
+                $combined
+                  .= 'Read more in '
+                  . $self->oxford_enumeration('and', @see_also_markdown)
+                  . $DOT
+                  . $NEWLINE;
+            }
+
+            my $reason_prefix = 'Reason: ';
+            my $plain = markdown_to_plain($combined,
+                $columns - length($SCREEN_PREFIX . $reason_prefix));
+
+            my @lines = split(/\n/, $plain);
+            $wrapped
+              .= $SCREEN_PREFIX . $reason_prefix . (shift @lines) . $NEWLINE;
+            $wrapped
+              .= $SCREEN_PREFIX
+              . $SPACE x (length $reason_prefix)
+              . $_
+              . $NEWLINE
+              for @lines;
+        }
+
+    } else {
+        $wrapped
+          .= wrap($DESCRIPTION_PREFIX, $DESCRIPTION_PREFIX, 'Unknown tag.');
+    }
+
+    $wrapped .= $COMMENT_PREFIX . $NEWLINE;
+
+    print encode_utf8($wrapped);
+
+    return;
+}
+
+=item markdown_to_plain
+
+=cut
+
+sub markdown_to_plain {
+    my ($markdown, $columns) = @_;
+
+    # use angular brackets for emphasis
+    $markdown =~ s{<i>|<em>}{&lt;}g;
+    $markdown =~ s{</i>|</em>}{&gt;}g;
+
+    # drop Markdown hyperlinks
+    $markdown =~ s{\[([^\]]+)\]\([^\)]+\)}{$1}g;
+
+    # drop all HTML tags except Markdown shorthand <$url>
+    $markdown =~ s{<(?![a-z]+://)[^>]+>}{}g;
+
+    # drop brackets around Markdown shorthand <$url>
+    $markdown =~ s{<([a-z]+://[^>]+)>}{$1}g;
+
+    # substitute HTML entities
+    my $plain = decode_entities($markdown);
+
+    local $Text::Wrap::columns = $columns
+      if defined $columns;
+
+    # do not wrap long words such as urls; see #719769
+    local $Text::Wrap::huge = 'overflow';
+
+    my @paragraphs = split(/\n{2,}/, $plain);
+
+    my @lines;
+    for my $paragraph (@paragraphs) {
+
+        # do not wrap preformatted paragraphs
+        unless ($paragraph =~ /^\s/) {
+
+            # reduce whitespace throughout, including newlines
+            $paragraph =~ s/\s+/ /g;
+
+            # trim beginning and end of each line
+            $paragraph =~ s/^\s+|\s+$//mg;
+
+            $paragraph = wrap($EMPTY, $EMPTY, $paragraph);
+        }
+
+        push(@lines, $EMPTY);
+        push(@lines, split(/\n/, $paragraph));
+    }
+
+    # drop leading blank line
+    shift @lines;
+
+    my $wrapped;
+    $wrapped .= $_ . $NEWLINE for @lines;
+
+    return $wrapped;
+}
+
+=back
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Output/Grammar.pm b/lib/Lintian/Output/Grammar.pm
new file mode 100644
index 0000000..e9d62bd
--- /dev/null
+++ b/lib/Lintian/Output/Grammar.pm
@@ -0,0 +1,84 @@
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Output::Grammar;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Moo::Role;
+use namespace::clean;
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $COMMA => q{,};
+
+=head1 NAME
+
+Lintian::Output::Grammar - sentence helpers
+
+=head1 SYNOPSIS
+
+    use Lintian::Output::Grammar;
+
+=head1 DESCRIPTION
+
+Helps with human readable output.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item oxford_enumeration
+
+=cut
+
+sub oxford_enumeration {
+    my ($self, $conjunctive, @alternatives) = @_;
+
+    return $EMPTY
+      unless @alternatives;
+
+    # remove and save last element
+    my $final = pop @alternatives;
+
+    my $maybe_comma = (@alternatives > 1 ? $COMMA : $EMPTY);
+
+    my $text = $EMPTY;
+    $text = join($COMMA . $SPACE, @alternatives) . "$maybe_comma $conjunctive "
+      if @alternatives;
+
+    $text .= $final;
+
+    return $text;
+}
+
+=back
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Output/HTML.pm b/lib/Lintian/Output/HTML.pm
new file mode 100644
index 0000000..8fd1126
--- /dev/null
+++ b/lib/Lintian/Output/HTML.pm
@@ -0,0 +1,331 @@
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Output::HTML;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Path::Tiny;
+use Text::Markdown::Discount qw(markdown);
+use Text::Xslate qw(mark_raw);
+use Time::Duration;
+use Time::Moment;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Output::Markdown qw(markdown_citation);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $NEWLINE => qq{\n};
+const my $PARAGRAPH_BREAK => $NEWLINE x 2;
+
+const my %CODE_PRIORITY => (
+    'E' => 30,
+    'W' => 40,
+    'I' => 50,
+    'P' => 60,
+    'X' => 70,
+    'C' => 80,
+    'O' => 90,
+    'M' => 100,
+);
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Output::Grammar';
+
+=head1 NAME
+
+Lintian::Output::HTML - standalone HTML hint output
+
+=head1 SYNOPSIS
+
+    use Lintian::Output::HTML;
+
+=head1 DESCRIPTION
+
+Provides standalone HTML hint output.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item issue_hints
+
+Print all hints passed in array. A separate arguments with processables
+is necessary to report in case no hints were found.
+
+=cut
+
+sub issue_hints {
+    my ($self, $profile, $groups) = @_;
+
+    $groups //= [];
+
+    my %output;
+
+    my $lintian_version = $ENV{LINTIAN_VERSION};
+    $output{'lintian-version'} = $lintian_version;
+
+    my @allgroups_output;
+    $output{groups} = \@allgroups_output;
+
+    for my $group (sort { $a->name cmp $b->name } @{$groups}) {
+
+        my %group_output;
+
+        $group_output{'group-id'} = $group->name;
+        $group_output{name} = $group->source_name;
+        $group_output{version} = $group->source_version;
+
+        my $start = Time::Moment->from_string($group->processing_start);
+        my $end = Time::Moment->from_string($group->processing_end);
+        $group_output{start} = $start->strftime('%c');
+        $group_output{end} = $end->strftime('%c');
+        $group_output{duration} = duration($start->delta_seconds($end));
+
+        my @processables = $group->get_processables;
+        my $any_processable = shift @processables;
+        $group_output{'maintainer'}
+          = $any_processable->fields->value('Maintainer');
+
+        push(@allgroups_output, \%group_output);
+
+        my @allfiles_output;
+        $group_output{'input-files'} = \@allfiles_output;
+
+        for my $processable (sort {$a->path cmp $b->path}
+            $group->get_processables) {
+            my %file_output;
+            $file_output{filename} = path($processable->path)->basename;
+            $file_output{hints}
+              = $self->hintlist($profile, $processable->hints);
+            push(@allfiles_output, \%file_output);
+        }
+    }
+
+    my $style_sheet = $profile->data->style_sheet->css;
+
+    my $templatedir = "$ENV{LINTIAN_BASE}/templates";
+    my $tx = Text::Xslate->new(path => [$templatedir]);
+    my $page = $tx->render(
+        'standalone-html.tx',
+        {
+            title => 'Lintian Tags',
+            style_sheet => mark_raw($style_sheet),
+            output => \%output,
+        }
+    );
+
+    print encode_utf8($page);
+
+    return;
+}
+
+=item C<hintlist>
+
+=cut
+
+sub hintlist {
+    my ($self, $profile, $arrayref) = @_;
+
+    my %sorter;
+    for my $hint (@{$arrayref // []}) {
+
+        my $tag = $profile->get_tag($hint->tag_name);
+
+        my $override_status = 0;
+        $override_status = 1
+          if defined $hint->override || @{$hint->masks};
+
+        my $ranking_code = $tag->code;
+        $ranking_code = 'X'
+          if $tag->experimental;
+        $ranking_code = 'O'
+          if defined $hint->override;
+        $ranking_code = 'M'
+          if @{$hint->masks};
+
+        my $code_priority = $CODE_PRIORITY{$ranking_code};
+
+        push(
+            @{
+                $sorter{$override_status}{$code_priority}{$tag->name}
+                  {$hint->context}
+            },
+            $hint
+        );
+    }
+
+    my @sorted;
+    for my $override_status (sort keys %sorter) {
+        my %by_code_priority = %{$sorter{$override_status}};
+
+        for my $code_priority (sort { $a <=> $b } keys %by_code_priority) {
+            my %by_tag_name = %{$by_code_priority{$code_priority}};
+
+            for my $tag_name (sort keys %by_tag_name) {
+                my %by_context = %{$by_tag_name{$tag_name}};
+
+                for my $context (sort keys %by_context) {
+
+                    my $hints
+                      = $sorter{$override_status}{$code_priority}{$tag_name}
+                      {$context};
+
+                    push(@sorted, $_)for @{$hints};
+                }
+            }
+        }
+    }
+
+    my @html_hints;
+    for my $hint (@sorted) {
+
+        my $tag = $profile->get_tag($hint->tag_name);
+
+        my %html_hint;
+        push(@html_hints, \%html_hint);
+
+        $html_hint{tag_name} = $hint->tag_name;
+
+        $html_hint{url} = 'https://lintian.debian.org/tags/' . $hint->tag_name;
+
+        $html_hint{context} = $hint->context
+          if length $hint->context;
+
+        $html_hint{visibility} = $tag->visibility;
+
+        $html_hint{visibility} = 'experimental'
+          if $tag->experimental;
+
+        my @comments;
+        if ($hint->override) {
+
+            $html_hint{visibility} = 'override';
+
+            push(@comments, $hint->override->justification)
+              if length $hint->override->justification;
+        }
+
+        # order matters
+        $html_hint{visibility} = 'mask'
+          if @{ $hint->masks };
+
+        for my $mask (@{$hint->masks}) {
+
+            push(@comments, 'masked by screen ' . $mask->screen);
+            push(@comments, $mask->excuse)
+              if length $mask->excuse;
+        }
+
+        $html_hint{comments} = \@comments
+          if @comments;
+    }
+
+    return \@html_hints;
+}
+
+=item describe_tags
+
+=cut
+
+sub describe_tags {
+    my ($self, $data, $tags) = @_;
+
+    for my $tag (@{$tags}) {
+
+        say encode_utf8('<p>Name: ' . $tag->name . '</p>');
+        say encode_utf8($EMPTY);
+
+        print encode_utf8(markdown($self->markdown_description($data, $tag)));
+    }
+
+    return;
+}
+
+=item markdown_description
+
+=cut
+
+sub markdown_description {
+    my ($self, $data, $tag) = @_;
+
+    my $description = $tag->explanation;
+
+    my @extras;
+
+    if (@{$tag->see_also}) {
+
+        my @markdown
+          = map { markdown_citation($data, $_) } @{$tag->see_also};
+        my $references
+          = 'Please refer to '
+          . $self->oxford_enumeration('and', @markdown)
+          . ' for details.';
+
+        push(@extras, $references);
+    }
+
+    push(@extras, 'Visibility: '. $tag->visibility);
+
+    push(@extras, 'Check: ' . $tag->check)
+      if length $tag->check;
+
+    push(@extras, 'Renamed from: ' . join($SPACE, @{$tag->renamed_from}))
+      if @{$tag->renamed_from};
+
+    push(@extras, 'This tag is experimental.')
+      if $tag->experimental;
+
+    push(@extras,
+        'This tag is a classification. There is no issue in your package.')
+      if $tag->visibility eq 'classification';
+
+    for my $screen (@{$tag->screens}) {
+
+        my $screen_description = 'Screen: ' . $screen->name . $NEWLINE;
+        $screen_description
+          .= 'Advocates: ' . join(', ', @{$screen->advocates}) . $NEWLINE;
+        $screen_description .= 'Reason: ' . $screen->reason . $NEWLINE;
+
+        $screen_description .= 'See-Also: ' . $NEWLINE;
+
+        push(@extras, $screen_description);
+    }
+
+    $description .= $PARAGRAPH_BREAK . $_ for @extras;
+
+    return $description;
+}
+
+=back
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Output/JSON.pm b/lib/Lintian/Output/JSON.pm
new file mode 100644
index 0000000..08996e2
--- /dev/null
+++ b/lib/Lintian/Output/JSON.pm
@@ -0,0 +1,322 @@
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Output::JSON;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Time::Piece;
+use JSON::MaybeXS;
+
+use Lintian::Output::Markdown qw(markdown_citation);
+
+const my $EMPTY => q{};
+
+const my %CODE_PRIORITY => (
+    'E' => 30,
+    'W' => 40,
+    'I' => 50,
+    'P' => 60,
+    'X' => 70,
+    'C' => 80,
+    'O' => 90,
+    'M' => 100,
+);
+
+use Moo;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Output::JSON - JSON hint output
+
+=head1 SYNOPSIS
+
+    use Lintian::Output::JSON;
+
+=head1 DESCRIPTION
+
+Provides JSON hint output.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item issue_hints
+
+Print all hints passed in array. A separate arguments with processables
+is necessary to report in case no hints were found.
+
+=cut
+
+sub issue_hints {
+    my ($self, $profile, $groups) = @_;
+
+    $groups //= [];
+
+    my %output;
+
+    $output{lintian_version} = $ENV{LINTIAN_VERSION};
+
+    my @allgroups_output;
+    $output{groups} = \@allgroups_output;
+
+    for my $group (sort { $a->name cmp $b->name } @{$groups}) {
+
+        my %group_output;
+        $group_output{group_id} = $group->name;
+        $group_output{source_name} = $group->source_name;
+        $group_output{source_version} = $group->source_version;
+
+        push(@allgroups_output, \%group_output);
+
+        my @allfiles_output;
+        $group_output{input_files} = \@allfiles_output;
+
+        for my $processable (sort {$a->path cmp $b->path}
+            $group->get_processables) {
+
+            my %file_output;
+            $file_output{path} = $processable->path;
+            $file_output{hints}
+              = $self->hintlist($profile, $processable->hints);
+
+            push(@allfiles_output, \%file_output);
+        }
+    }
+
+    # convert to UTF-8 prior to encoding in JSON
+    my $encoder = JSON->new;
+    $encoder->canonical;
+    $encoder->utf8;
+    $encoder->pretty;
+
+    my $json = $encoder->encode(\%output);
+
+    # output encoded JSON; is already in UTF-8
+    print $json;
+
+    return;
+}
+
+=item C<hintlist>
+
+=cut
+
+sub hintlist {
+    my ($self, $profile, $arrayref) = @_;
+
+    my %sorter;
+    for my $hint (@{$arrayref // []}) {
+
+        my $tag = $profile->get_tag($hint->tag_name);
+
+        my $override_status = 0;
+        $override_status = 1
+          if defined $hint->override || @{$hint->masks};
+
+        my $ranking_code = $tag->code;
+        $ranking_code = 'X'
+          if $tag->experimental;
+        $ranking_code = 'O'
+          if defined $hint->override;
+        $ranking_code = 'M'
+          if @{$hint->masks};
+
+        my $code_priority = $CODE_PRIORITY{$ranking_code};
+
+        push(
+            @{
+                $sorter{$override_status}{$code_priority}{$tag->name}
+                  {$hint->context}
+            },
+            $hint
+        );
+    }
+
+    my @sorted;
+    for my $override_status (sort keys %sorter) {
+        my %by_code_priority = %{$sorter{$override_status}};
+
+        for my $code_priority (sort { $a <=> $b } keys %by_code_priority) {
+            my %by_tag_name = %{$by_code_priority{$code_priority}};
+
+            for my $tag_name (sort keys %by_tag_name) {
+                my %by_context = %{$by_tag_name{$tag_name}};
+
+                for my $context (sort keys %by_context) {
+
+                    my $hints
+                      = $sorter{$override_status}{$code_priority}{$tag_name}
+                      {$context};
+
+                    push(@sorted, $_)for @{$hints};
+                }
+            }
+        }
+    }
+
+    my @hint_dictionaries;
+    for my $hint (@sorted) {
+
+        my $tag = $profile->get_tag($hint->tag_name);
+
+        my %hint_dictionary;
+        push(@hint_dictionaries, \%hint_dictionary);
+
+        $hint_dictionary{tag} = $tag->name;
+        $hint_dictionary{note} = $hint->note;
+
+        if ($hint->can('pointer')) {
+            my $pointer = $hint->pointer;
+
+            my %pointer_dictionary;
+
+            if ($pointer->can('item')) {
+                my $item = $pointer->item;
+
+                my %item_dictionary;
+                $item_dictionary{name} = $item->name;
+                $item_dictionary{index} = $item->index->identifier;
+
+                $pointer_dictionary{item} = \%item_dictionary;
+
+                # numerify to force JSON integer
+                # https://metacpan.org/pod/JSON::XS#simple-scalars
+                $pointer_dictionary{line_position} = $pointer->position + 0;
+            }
+
+            $hint_dictionary{pointer} = \%pointer_dictionary;
+        }
+
+        $hint_dictionary{visibility} = $tag->visibility;
+        $hint_dictionary{experimental}
+          = ($tag->experimental ? JSON()->true : JSON()->false);
+
+        for my $mask (@{ $hint->masks }) {
+
+            my %mask_dictionary;
+            $mask_dictionary{screen} = $mask->screen;
+            $mask_dictionary{excuse} = $mask->excuse;
+
+            push(@{$hint_dictionary{masks}}, \%mask_dictionary);
+        }
+
+        if ($hint->override) {
+
+            my %override_dictionary;
+            $override_dictionary{justification}
+              = $hint->override->justification;
+
+            $hint_dictionary{override} = \%override_dictionary;
+        }
+    }
+
+    return \@hint_dictionaries;
+}
+
+=item describe_tags
+
+=cut
+
+sub describe_tags {
+    my ($self, $data, $tags) = @_;
+
+    my @tag_dictionaries;
+
+    for my $tag (@{$tags}) {
+
+        my %tag_dictionary;
+        push(@tag_dictionaries, \%tag_dictionary);
+
+        $tag_dictionary{name} = $tag->name;
+        $tag_dictionary{name_spaced}
+          = ($tag->name_spaced ? JSON()->true : JSON()->false);
+        $tag_dictionary{show_always}
+          = ($tag->show_always ? JSON()->true : JSON()->false);
+
+        $tag_dictionary{explanation} = $tag->explanation;
+
+        my @tag_see_also_markdown
+          = map { markdown_citation($data, $_) } @{$tag->see_also};
+        $tag_dictionary{see_also} = \@tag_see_also_markdown;
+
+        $tag_dictionary{check} = $tag->check;
+        $tag_dictionary{visibility} = $tag->visibility;
+        $tag_dictionary{experimental}
+          = ($tag->experimental ? JSON()->true : JSON()->false);
+
+        $tag_dictionary{renamed_from} = $tag->renamed_from;
+
+        my @screen_dictionaries;
+
+        for my $screen (@{$tag->screens}) {
+
+            my %screen_dictionary;
+            push(@screen_dictionaries, \%screen_dictionary);
+
+            $screen_dictionary{name} = $screen->name;
+
+            my @advocate_emails = map { $_->format } @{$screen->advocates};
+            $screen_dictionary{advocates} = \@advocate_emails;
+
+            $screen_dictionary{reason} = $screen->reason;
+
+            my @screen_see_also_markdown
+              = map { markdown_citation($data, $_) } @{$screen->see_also};
+            $screen_dictionary{see_also} = \@screen_see_also_markdown;
+        }
+
+        $tag_dictionary{screens} = \@screen_dictionaries;
+
+        $tag_dictionary{lintian_version} = $ENV{LINTIAN_VERSION};
+    }
+
+    # convert to UTF-8 prior to encoding in JSON
+    my $encoder = JSON->new;
+    $encoder->canonical;
+    $encoder->utf8;
+    $encoder->pretty;
+
+    # encode single tags without array bracketing
+    my $object = \@tag_dictionaries;
+    $object = shift @tag_dictionaries
+      if @tag_dictionaries == 1;
+
+    my $json = $encoder->encode($object);
+
+    # output encoded JSON; is already in UTF-8
+    print $json;
+
+    return;
+}
+
+=back
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Output/Markdown.pm b/lib/Lintian/Output/Markdown.pm
new file mode 100644
index 0000000..5786612
--- /dev/null
+++ b/lib/Lintian/Output/Markdown.pm
@@ -0,0 +1,224 @@
+# -*- perl -*-
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Output::Markdown;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+our @EXPORT_OK = qw(
+  markdown_citation
+  markdown_authority
+  markdown_bug
+  markdown_manual_page
+  markdown_uri
+  markdown_hyperlink
+);
+
+use Const::Fast;
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+
+=head1 NAME
+
+Lintian::Output::Markdown - Lintian interface for markdown output
+
+=head1 SYNOPSIS
+
+    use Lintian::Output::Markdown;
+
+=head1 DESCRIPTION
+
+Lintian::Output::Markdown provides functions for Markdown output.
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item markdown_citation
+
+=cut
+
+sub markdown_citation {
+    my ($data, $citation) = @_;
+
+    if ($citation =~ m{^ ([\w-]+) \s+ (.+) $}x) {
+
+        my $volume = $1;
+        my $section = $2;
+
+        my $markdown = $data->markdown_authority_reference($volume, $section);
+
+        $markdown ||= $citation;
+
+        return $markdown;
+    }
+
+    if ($citation =~ m{^ ([\w.-]+) [(] (\d\w*) [)] $}x) {
+
+        my $name = $1;
+        my $section = $2;
+
+        return markdown_manual_page($name, $section);
+    }
+
+    if ($citation =~ m{^(?:Bug)?#(\d+)$}) {
+
+        my $number = $1;
+        return markdown_bug($number);
+    }
+
+    # turn bare file into file uris
+    $citation =~ s{^ / }{file://}x;
+
+    # strip scheme from uri
+    if ($citation =~ s{^ (\w+) : // }{}x) {
+
+        my $scheme = $1;
+
+        return markdown_uri($scheme, $citation);
+    }
+
+    return $citation;
+}
+
+=item markdown_authority
+
+=cut
+
+sub markdown_authority {
+    my ($volume_title, $volume_url, $section_key, $section_title,$section_url)
+      = @_;
+
+    my $directed_link;
+    $directed_link = markdown_hyperlink($section_title, $section_url)
+      if length $section_title
+      && length $section_url;
+
+    my $pointer;
+    if (length $section_key) {
+
+        if ($section_key =~ /^[A-Z]+$/ || $section_key =~ /^appendix-/) {
+            $pointer = "Appendix $section_key";
+
+        } elsif ($section_key =~ /^\d+$/) {
+            $pointer = "Chapter $section_key";
+
+        } else {
+            $pointer = "Section $section_key";
+        }
+    }
+
+    # overall manual.
+    my $volume_link = markdown_hyperlink($volume_title, $volume_url);
+
+    if (length $directed_link) {
+
+        return "$directed_link ($pointer) in the $volume_title"
+          if length $pointer;
+
+        return "$directed_link in the $volume_title";
+    }
+
+    return "$pointer of the $volume_link"
+      if length $pointer;
+
+    return "the $volume_link";
+}
+
+=item markdown_bug
+
+=cut
+
+sub markdown_bug {
+    my ($number) = @_;
+
+    return markdown_hyperlink("Bug#$number","https://bugs.debian.org/$number");
+}
+
+=item markdown_manual_page
+
+=cut
+
+sub markdown_manual_page {
+    my ($name, $section) = @_;
+
+    my $url
+      ="https://manpages.debian.org/cgi-bin/man.cgi?query=$name&amp;sektion=$section";
+    my $hyperlink = markdown_hyperlink("$name($section)", $url);
+
+    return "the $hyperlink manual page";
+}
+
+=item markdown_uri
+
+=cut
+
+sub markdown_uri {
+    my ($scheme, $locator) = @_;
+
+    my $url = "$scheme://$locator";
+
+    # use plain path as label for files
+    return markdown_hyperlink($locator, $url)
+      if $scheme eq 'file';
+
+    # or nothing for everything else
+    return markdown_hyperlink($EMPTY, $url);
+}
+
+=item markdown_hyperlink
+
+=cut
+
+sub markdown_hyperlink {
+    my ($text, $url) = @_;
+
+    return $text
+      unless length $url;
+
+    return "<$url>"
+      unless length $text;
+
+    return "[$text]($url)";
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Output/Universal.pm b/lib/Lintian/Output/Universal.pm
new file mode 100644
index 0000000..a16da49
--- /dev/null
+++ b/lib/Lintian/Output/Universal.pm
@@ -0,0 +1,151 @@
+# Copyright (C) 2019-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Output::Universal;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp;
+use Const::Fast;
+use List::SomeUtils qw(all);
+use Unicode::UTF8 qw(encode_utf8);
+
+const my $SPACE => q{ };
+const my $COLON => q{:};
+const my $LEFT_PARENTHESIS => q{(};
+const my $RIGHT_PARENTHESIS => q{)};
+
+use Moo;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Output::Universal -- Facilities for printing universal hints
+
+=head1 SYNOPSIS
+
+ use Lintian::Output::Universal;
+
+=head1 DESCRIPTION
+
+A class for printing hints using the 'universal' format.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item issue_hints
+
+Passing all groups with all processables in case no hints were found.
+
+=cut
+
+sub issue_hints {
+    my ($self, $profile, $groups) = @_;
+
+    for my $group (@{$groups // []}) {
+
+        my @by_group;
+        for my $processable ($group->get_processables) {
+
+            for my $hint (@{$processable->hints}) {
+
+                my $line
+                  = $processable->name
+                  . $SPACE
+                  . $LEFT_PARENTHESIS
+                  . $processable->type
+                  . $RIGHT_PARENTHESIS
+                  . $COLON
+                  . $SPACE
+                  . $hint->tag_name;
+
+                $line .= $SPACE . $hint->context
+                  if length $hint->context;
+
+                push(@by_group, $line);
+            }
+        }
+
+        my @sorted
+          = reverse sort { order($a) cmp order($b) } @by_group;
+
+        say encode_utf8($_) for @sorted;
+    }
+
+    return;
+}
+
+=item order
+
+=cut
+
+sub order {
+    my ($line) = @_;
+
+    return package_type($line) . $line;
+}
+
+=item package_type
+
+=cut
+
+sub package_type {
+    my ($line) = @_;
+
+    my (undef, $type, undef, undef) = parse_line($line);
+    return $type;
+}
+
+=item parse_line
+
+=cut
+
+sub parse_line {
+    my ($line) = @_;
+
+    my ($package, $type, $name, $details)
+      = $line =~ qr/^(\S+)\s+\(([^)]+)\):\s+(\S+)(?:\s+(.*))?$/;
+
+    croak encode_utf8("Cannot parse line $line")
+      unless all { length } ($package, $type, $name);
+
+    return ($package, $type, $name, $details);
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Override.pm b/lib/Lintian/Override.pm
new file mode 100644
index 0000000..c62788d
--- /dev/null
+++ b/lib/Lintian/Override.pm
@@ -0,0 +1,86 @@
+# -*- perl -*- Lintian::Override
+#
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Override;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+const my $EMPTY => q{};
+
+use Moo;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Override - access to override data
+
+=head1 SYNOPSIS
+
+    use Lintian::Override;
+
+=head1 DESCRIPTION
+
+Lintian::Override provides access to override data.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item tag_name
+
+=item architectures
+
+=item pattern
+
+=item justification
+
+=item position
+
+=cut
+
+has tag_name => (is => 'rw', default => $EMPTY);
+has architectures => (is => 'rw', default => sub { [] });
+
+has pattern => (is => 'rw', default => $EMPTY);
+
+has justification => (is => 'rw', default => $EMPTY);
+has position => (is => 'rw');
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Pointer/Item.pm b/lib/Lintian/Pointer/Item.pm
new file mode 100644
index 0000000..6622fc8
--- /dev/null
+++ b/lib/Lintian/Pointer/Item.pm
@@ -0,0 +1,100 @@
+# Copyright (C) 2021 Felix Lechner <felix.lechner@lease-up.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Pointer::Item;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+const my $EMPTY => q{};
+const my $COLON => q{:};
+
+=head1 NAME
+
+Lintian::Pointer::Item -- Facilities for pointing into specific index items
+
+=head1 SYNOPSIS
+
+use Lintian::Pointer::Item;
+
+=head1 DESCRIPTION
+
+A class for item pointers
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item item
+
+=item position
+
+=cut
+
+has item => (is => 'rw');
+has position => (
+    is => 'rw',
+    coerce => sub { my ($number) = @_; return $number // 0;},
+    default => 0
+);
+
+=item to_string
+
+=cut
+
+sub to_string {
+    my ($self) = @_;
+
+    croak encode_utf8('No item')
+      unless defined $self->item;
+
+    my $text = $self->item->name;
+
+    $text .= $COLON . $self->position
+      if $self->position > 0;
+
+    return $text;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Pool.pm b/lib/Lintian/Pool.pm
new file mode 100644
index 0000000..db153f9
--- /dev/null
+++ b/lib/Lintian/Pool.pm
@@ -0,0 +1,412 @@
+# Copyright (C) 2011 Niels Thykier <niels@thykier.net>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+## Represents a pool of processables (Lintian::Processable)
+package Lintian::Pool;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Cwd qw(getcwd);
+use List::SomeUtils qw(any);
+use Time::HiRes qw(gettimeofday tv_interval);
+use Path::Tiny;
+use POSIX qw(:sys_wait_h);
+use Proc::ProcessTable;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Group;
+
+const my $SPACE => q{ };
+const my $COMMA => q{,};
+const my $SEMICOLON => q{;};
+const my $LEFT_PARENS => q{(};
+const my $RIGHT_PARENS => q{)};
+const my $PLURAL_S => q{s};
+
+const my $ANY_CHILD => -1;
+const my $WORLD_WRITABLE_FOLDER => oct(777);
+
+use Moo;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Pool -- Pool of processables
+
+=head1 SYNOPSIS
+
+ use Lintian::Pool;
+ 
+ my $pool = Lintian::Pool->new;
+ $pool->add_file('foo.changes');
+ $pool->add_file('bar.dsc');
+ $pool->add_file('baz.deb');
+ $pool->add_file('qux.buildinfo');
+ foreach my $gname ($pool->get_group_names){
+    my $group = $pool->get_group($gname);
+    process($gname, $group);
+ }
+
+=head1 METHODS
+
+=over 4
+
+=item $pool->groups
+
+Returns a hash reference to the list of processable groups that are currently
+in the pool. The key is a unique identifier based on name and version.
+
+=item C<savedir>
+
+=cut
+
+has groups => (is => 'rw', default => sub{ {} });
+
+has savedir => (is => 'rw', default => sub{ getcwd; });
+
+# must be absolute; frontend/lintian depends on it
+has basedir => (
+    is => 'rw',
+    default => sub {
+
+        my $absolute
+          = Path::Tiny->tempdir(TEMPLATE => 'lintian-pool-XXXXXXXXXX');
+
+        $absolute->mkpath({mode => $WORLD_WRITABLE_FOLDER});
+
+        return $absolute;
+    }
+);
+
+=item $pool->basedir
+
+Returns the base directory for the pool. Most likely it's a temporary directory.
+
+=item $pool->add_group($group)
+
+Adds a group to the pool.
+
+=cut
+
+sub add_group {
+    my ($self, $group) = @_;
+
+    my $name = $group->name;
+
+    unless (exists $self->groups->{$name}){
+
+        # group does not exist; just add whole
+        $self->groups->{$name} = $group;
+
+        return 1;
+    }
+
+    # group exists; merge & accept all new
+    my $added = 0;
+
+    my $old = $self->groups->{$name};
+
+    for my $type (qw/source buildinfo changes/) {
+
+        if (!defined $old->$type && defined $group->$type) {
+            $old->add_processable($group->$type);
+            $added = 1;
+        }
+    }
+
+    for my $installable ($group->get_installables){
+        # New binary package ?
+        my $was_new = $old->add_processable($installable);
+        $added ||= $was_new;
+    }
+
+    return $added;
+}
+
+=item $pool->process
+
+Process the pool.
+
+=cut
+
+sub process{
+    my ($self, $PROFILE, $exit_code_ref, $option)= @_;
+
+    if ($self->empty) {
+        say {*STDERR} encode_utf8('No packages selected.');
+        return;
+    }
+
+    my %reported_count;
+    my %override_count;
+    my %ignored_overrides;
+    my $unused_overrides = 0;
+
+    for my $group (values %{$self->groups}) {
+
+        my $total_start = [gettimeofday];
+
+        $group->profile($PROFILE);
+        $group->jobs($option->{'jobs'});
+
+        my $success= $group->process(\%ignored_overrides, $option);
+
+        for my $processable ($group->get_processables){
+
+            my @keep;
+            for my $hint (@{$processable->hints}) {
+
+                my $tag = $PROFILE->get_tag($hint->tag_name);
+
+                # discard experimental tags
+                next
+                  if $tag->experimental
+                  && !$option->{'display-experimental'};
+
+                # discard overridden tags
+                next
+                  if defined $hint->override
+                  && !$option->{'show-overrides'};
+
+                # discard outside the selected display level
+                next
+                  unless $PROFILE->display_level_for_tag($hint->tag_name);
+
+                if (!defined $hint->override) {
+
+                    ++$reported_count{$tag->visibility}
+                      if !$tag->experimental;
+
+                    ++$reported_count{experimental}
+                      if $tag->experimental;
+                }
+
+                ++$reported_count{override}
+                  if defined $hint->override;
+
+                ++$unused_overrides
+                  if $hint->tag_name eq 'unused-override'
+                  || $hint->tag_name eq 'mismatched-override';
+
+                push(@keep, $hint);
+            }
+
+            $processable->hints(\@keep);
+        }
+
+        ${$exit_code_ref} = 2
+          if $success && any { $reported_count{$_} } @{$option->{'fail-on'}};
+
+        # interruptions can leave processes behind (manpages); wait and reap
+        if (${$exit_code_ref} == 1) {
+            1 while waitpid($ANY_CHILD, WNOHANG) > 0;
+        }
+
+        if ($option->{debug}) {
+            my $process_table = Proc::ProcessTable->new;
+            my @leftover= grep { $_->ppid == $$ } @{$process_table->table};
+
+            # announce left over processes, see commit 3bbcc3b
+            if (@leftover) {
+                warn encode_utf8(
+                    "\nSome processes were left over (maybe unreaped):\n");
+
+                my $FORMAT = '    %-12s %-12s %-8s %-24s %s';
+                say encode_utf8(
+                    sprintf(
+                        $FORMAT,'PID', 'TTY', 'STATUS', 'START', 'COMMAND'
+                    )
+                );
+
+                say encode_utf8(
+                    sprintf($FORMAT,
+                        $_->pid,$_->ttydev,
+                        $_->state,scalar(localtime($_->start)),
+                        $_->cmndline)
+                )for @leftover;
+
+                ${$exit_code_ref} = 1;
+                die encode_utf8("Aborting.\n");
+            }
+        }
+
+        my $total_raw_res = tv_interval($total_start);
+        my $total_tres = sprintf('%.3fs', $total_raw_res);
+
+        my $status = $success ? 'complete' : 'error';
+        say {*STDERR}
+          encode_utf8($status . $SPACE . $group->name . " ($total_tres)")
+          if $option->{'status-log'};
+        say {*STDERR} encode_utf8('Finished processing group ' . $group->name)
+          if $option->{debug};
+
+        ${$exit_code_ref} = 1
+          unless $success;
+    }
+
+    my $OUTPUT;
+    if ($option->{'output-format'} eq 'html') {
+        require Lintian::Output::HTML;
+        $OUTPUT = Lintian::Output::HTML->new;
+    } elsif ($option->{'output-format'} eq 'json') {
+        require Lintian::Output::JSON;
+        $OUTPUT = Lintian::Output::JSON->new;
+    } elsif ($option->{'output-format'} eq 'universal') {
+        require Lintian::Output::Universal;
+        $OUTPUT = Lintian::Output::Universal->new;
+    } else {
+        require Lintian::Output::EWI;
+        $OUTPUT = Lintian::Output::EWI->new;
+    }
+
+    # pass everything, in case some groups or processables have no hints
+    $OUTPUT->issue_hints($PROFILE, [values %{$self->groups}], $option);
+
+    my $errors = $override_count{error} // 0;
+    my $warnings = $override_count{warning} // 0;
+    my $info = $override_count{info} // 0;
+    my $total = $errors + $warnings + $info;
+
+    if (   $option->{'output-format'} eq 'ewi'
+        && !$option->{'no-override'}
+        && !$option->{'show-overrides'}
+        && ($total > 0 || $unused_overrides > 0)) {
+
+        my @details;
+        push(@details, quantity($errors, 'error'))
+          if $errors;
+        push(@details, quantity($warnings, 'warning'))
+          if $warnings;
+        push(@details, "$info info")
+          if $info;
+
+        my $text = quantity($total, 'hint') . ' overridden';
+        $text
+          .= $SPACE
+          . $LEFT_PARENS
+          . join($COMMA . $SPACE, @details)
+          . $RIGHT_PARENS
+          if @details;
+        $text
+          .= $SEMICOLON
+          . $SPACE
+          . quantity($unused_overrides, 'unused override');
+
+        say encode_utf8("N: $text");
+    }
+
+    if ($option->{'output-format'} eq 'ewi' && %ignored_overrides) {
+        say encode_utf8('N: Some overrides were ignored.');
+
+        if ($option->{verbose}) {
+            say encode_utf8(
+'N: The following tags had at least one override but are mandatory:'
+            );
+            say encode_utf8("N:   - $_") for sort keys %ignored_overrides;
+
+        } else {
+            say encode_utf8('N: Use --verbose for more information.');
+        }
+    }
+
+    path($self->basedir)->remove_tree
+      if length $self->basedir && -d $self->basedir;
+
+    return;
+}
+
+=item quantity
+
+=cut
+
+sub quantity {
+    my ($count, $unit) = @_;
+
+    my $text = $count . $SPACE . $unit;
+    $text .= $PLURAL_S
+      unless $count == 1;
+
+    return $text;
+}
+
+=item $pool->get_group_names
+
+Returns the name of all the groups in this pool.
+
+Do not modify the list nor its contents.
+
+=cut
+
+sub get_group_names{
+    my ($self) = @_;
+
+    return keys %{ $self->groups };
+}
+
+=item $pool->get_group($name)
+
+Returns the group called $name or C<undef>
+if there is no group called $name.
+
+=cut
+
+sub get_group{
+    my ($self, $group) = @_;
+
+    return $self->groups->{$group};
+}
+
+=item $pool->empty
+
+Returns true if the pool is empty.
+
+=cut
+
+sub empty{
+    my ($self) = @_;
+
+    return scalar keys %{$self->groups} == 0;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Niels Thykier <niels@thykier.net> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+L<Lintian::Processable>
+
+L<Lintian::Group>
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable.pm b/lib/Lintian/Processable.pm
new file mode 100644
index 0000000..c89a1fc
--- /dev/null
+++ b/lib/Lintian/Processable.pm
@@ -0,0 +1,302 @@
+# Copyright (C) 2011 Niels Thykier <niels@thykier.net>
+# Copyright (C) 2019-2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Processable;
+
+use v5.20;
+use warnings;
+use utf8;
+use warnings::register;
+
+use Const::Fast;
+use File::Basename;
+use Path::Tiny;
+
+use Moo::Role;
+use MooX::Aliases;
+use namespace::clean;
+
+const my $EMPTY => q{};
+const my $COLON => q{:};
+const my $SLASH => q{/};
+const my $UNDERSCORE => q{_};
+const my $EVIL_CHARACTERS => qr{[/&|;\$"'<>]};
+
+=encoding utf-8
+
+=head1 NAME
+
+Lintian::Processable -- An (abstract) object that Lintian can process
+
+=head1 SYNOPSIS
+
+ use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Instances of this perl class are objects that Lintian can process (e.g.
+deb files).  Multiple objects can then be combined into
+L<groups|Lintian::Group>, which Lintian will process
+together.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item name
+
+Returns the name of the package.
+
+=item type
+
+Returns the type of package (e.g. binary, source, udeb ...)
+
+=item hints
+
+=item $proc->version
+
+Returns the version of the package.
+
+=item $proc->path
+
+Returns the path to the packaged version of actual package.  This path
+is used in case the data needs to be extracted from the package.
+
+=item basename
+
+Returns the basename of the package path.
+
+=item $proc->architecture
+
+Returns the architecture(s) of the package. May return multiple values
+from changes processables.  For source processables it is "source".
+
+=item $proc->source_name
+
+Returns the name of the source package.
+
+=item $proc->source_version
+
+Returns the version of the source package.
+
+=item $proc->tainted
+
+Returns a truth value if one or more fields in this Processable is
+tainted.  On a best effort basis tainted fields will be sanitized
+to less dangerous (but possibly invalid) values.
+
+=item fields
+
+Lintian::Deb822::Section with primary field values.
+
+=item $proc->pooldir
+
+Returns a reference to lab this Processable is in.
+
+=item $proc->basedir
+
+Returns the base directory of this package inside the lab.
+
+=cut
+
+has path => (
+    is => 'rw',
+    default => $EMPTY,
+    trigger => sub {
+        my ($self, $path) = @_;
+
+        my $basename = basename($path);
+        $self->basename($basename);
+    }
+);
+has basename => (is => 'rw', default => $EMPTY);
+has type => (is => 'rw', default => $EMPTY);
+
+has hints => (is => 'rw', default => sub { [] });
+
+has architecture => (
+    is => 'rw',
+    coerce => sub {
+        my ($value) = @_;
+        return clean_field($value);
+    },
+    default => $EMPTY
+);
+has name => (
+    is => 'rw',
+    coerce => sub {
+        my ($value) = @_;
+        return clean_field($value);
+    },
+    default => $EMPTY
+);
+has source_name => (
+    is => 'rw',
+    coerce => sub {
+        my ($value) = @_;
+        return clean_field($value);
+    },
+    default => $EMPTY
+);
+has source_version =>(
+    is => 'rw',
+    coerce => sub {
+        my ($value) = @_;
+        return clean_field($value);
+    },
+    default => $EMPTY
+);
+has version => (
+    is => 'rw',
+    coerce => sub {
+        my ($value) = @_;
+        return clean_field($value);
+    },
+    default => $EMPTY
+);
+
+has tainted => (is => 'rw', default => 0);
+
+has fields => (is => 'rw', default => sub { Lintian::Deb822::Section->new; });
+
+has pooldir => (is => 'rw', default => $EMPTY);
+has basedir => (
+    is => 'rw',
+    lazy => 1,
+    trigger => sub {
+        my ($self, $folder) = @_;
+
+        return
+          unless length $folder;
+
+        # create directory
+        path($folder)->mkpath
+          unless -e $folder;
+    },
+    default => sub {
+        my ($self) = @_;
+
+        my $path
+          = $self->source_name
+          . $SLASH
+          . $self->name
+          . $UNDERSCORE
+          . $self->version;
+        $path .= $UNDERSCORE . $self->architecture
+          unless $self->type eq 'source';
+        $path .= $UNDERSCORE . $self->type;
+
+        # architectures can contain spaces in changes files
+        $path =~ s/\s/-/g;
+
+        # colon can be a path separator
+        $path =~ s/:/_/g;
+
+        my $basedir = $self->pooldir . "/$path";
+
+        return $basedir;
+    }
+);
+
+=item C<identifier>
+
+Produces an identifier for this processable.  The identifier is
+based on the type, name, version and architecture of the package.
+
+=cut
+
+sub identifier {
+    my ($self) = @_;
+
+    my $id = $self->type . $COLON . $self->name . $UNDERSCORE . $self->version;
+
+    # add architecture unless it is source
+    $id .= $UNDERSCORE . $self->architecture
+      unless $self->type eq 'source';
+
+    $id =~ s/\s+/_/g;
+
+    return $id;
+}
+
+=item clean_field
+
+Cleans a field of evil characters to prevent traversal or worse.
+
+=cut
+
+sub clean_field {
+    my ($value) = @_;
+
+    # make sure none of the fields can cause traversal
+    my $clean = $value;
+    $clean =~ s/${$EVIL_CHARACTERS}/_/g;
+
+    return $clean;
+}
+
+=item guess_name
+
+=cut
+
+sub guess_name {
+    my ($self, $path) = @_;
+
+    my $guess = path($path)->basename;
+
+    # drop extension, to catch fields-general-missing.deb
+    $guess =~ s/\.[^.]*$//;
+
+    # drop everything after the first underscore, if any
+    $guess =~ s/_.*$//;
+
+    # 'path/lintian_2.5.2_amd64.changes' became 'lintian'
+    return $guess;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Niels Thykier <niels@thykier.net> for Lintian.
+Substantial portions written by Russ Allbery <rra@debian.org> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+L<Lintian::Processable::Installable>
+
+L<Lintian::Processable::Buildinfo>
+
+L<Lintian::Processable::Changes>
+
+L<Lintian::Processable::Source>
+
+L<Lintian::Group>
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Buildinfo.pm b/lib/Lintian/Processable/Buildinfo.pm
new file mode 100644
index 0000000..f5983fa
--- /dev/null
+++ b/lib/Lintian/Processable/Buildinfo.pm
@@ -0,0 +1,133 @@
+# Copyright (C) 2019-2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Processable::Buildinfo;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Deb822;
+
+use Moo;
+use namespace::clean;
+
+with
+  'Lintian::Processable',
+  'Lintian::Processable::Fields::Files',
+  'Lintian::Processable::Buildinfo::Overrides';
+
+=for Pod::Coverage BUILDARGS
+
+=head1 NAME
+
+Lintian::Processable::Buildinfo -- A buildinfo file Lintian can process
+
+=head1 SYNOPSIS
+
+ use Lintian::Processable::Buildinfo;
+
+ my $processable = Lintian::Processable::Buildinfo->new;
+ $processable->init_from_file('path');
+
+=head1 DESCRIPTION
+
+This class represents a 'buildinfo' file that Lintian can process. Objects
+of this kind are often part of a L<Lintian::Group>, which
+represents all the files in a changes or buildinfo file.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item init_from_file (PATH)
+
+Initializes a new object from PATH.
+
+=cut
+
+sub init_from_file {
+    my ($self, $file) = @_;
+
+    croak encode_utf8("File $file does not exist")
+      unless -e $file;
+
+    $self->path($file);
+    $self->type('buildinfo');
+
+    my $primary = Lintian::Deb822->new;
+    my @sections = $primary->read_file($self->path)
+      or croak encode_utf8(
+        $self->path. ' is not a valid '. $self->type . ' file');
+
+    $self->fields($sections[0]);
+
+    my $name = $self->fields->value('Source');
+    my $version = $self->fields->value('Version');
+    my $architecture = $self->fields->value('Architecture');
+
+    unless (length $name) {
+        $name = $self->guess_name($self->path);
+        croak encode_utf8('Cannot determine the name from '. $self->path)
+          unless length $name;
+    }
+
+    my $source_name = $name;
+    my $source_version = $version;
+
+    $self->name($name);
+    $self->version($version);
+    $self->architecture($architecture);
+    $self->source_name($source_name);
+    $self->source_version($source_version);
+
+    # make sure none of these fields can cause traversal
+    $self->tainted(1)
+      if $self->name ne $name
+      || $self->version ne $version
+      || $self->architecture ne $architecture
+      || $self->source_name ne $source_name
+      || $self->source_version ne $source_version;
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+L<Lintian::Processable>
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Buildinfo/Overrides.pm b/lib/Lintian/Processable/Buildinfo/Overrides.pm
new file mode 100644
index 0000000..136c01c
--- /dev/null
+++ b/lib/Lintian/Processable/Buildinfo/Overrides.pm
@@ -0,0 +1,94 @@
+# -*- perl -*- Lintian::Processable::Buildinfo::Overrides
+#
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Buildinfo::Overrides;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo::Role;
+use namespace::clean;
+
+with 'Lintian::Processable::Overrides';
+
+=head1 NAME
+
+Lintian::Processable::Buildinfo::Overrides - access to override data
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Buildinfo::Overrides provides an interface for overrides.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item override_file
+
+=cut
+
+has override_file => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return undef;
+    }
+);
+
+=item overrides
+
+=cut
+
+has overrides => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my @overrides;
+
+        return \@overrides;
+    }
+);
+
+1;
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Changelog/Version.pm b/lib/Lintian/Processable/Changelog/Version.pm
new file mode 100644
index 0000000..7721b17
--- /dev/null
+++ b/lib/Lintian/Processable/Changelog/Version.pm
@@ -0,0 +1,108 @@
+# -*- perl -*-
+# Lintian::Processable::Changelog::Version -- interface to source package data collection
+
+# Copyright (C) 2008 Russ Allbery
+# Copyright (C) 2009 Raphael Geissert
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Changelog::Version;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Syntax::Keyword::Try;
+
+use Lintian::Changelog::Version;
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::Changelog::Version - Lintian interface to source package data collection
+
+=head1 SYNOPSIS
+
+    my ($name, $type, $dir) = ('foobar', 'source', '/path/to/lab-entry');
+    my $collect = Lintian::Processable::Changelog::Version->new($name);
+    if ($collect->native) {
+        print "Package is native\n";
+    }
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Changelog::Version provides an interface to package data for source
+packages.  It implements data collection methods specific to source
+packages.
+
+This module is in its infancy.  Most of Lintian still reads all data from
+files in the laboratory whenever that data is needed and generates that
+data via collect scripts.  The goal is to eventually access all data about
+source packages via this module so that the module can cache data where
+appropriate and possibly retire collect scripts in favor of caching that
+data in memory.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item changelog_version
+
+Returns a fully parsed Lintian::Changelog::Version for the
+source package's version string.
+
+=cut
+
+has changelog_version => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $versionstring = $self->fields->value('Version');
+
+        my $version = Lintian::Changelog::Version->new;
+        try {
+            $version->assign($versionstring, $self->native);
+
+        } catch {
+        }
+
+        return $version;
+    }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Russ Allbery <rra@debian.org> for Lintian.
+Amended by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Changes.pm b/lib/Lintian/Processable/Changes.pm
new file mode 100644
index 0000000..65eb8e4
--- /dev/null
+++ b/lib/Lintian/Processable/Changes.pm
@@ -0,0 +1,145 @@
+# Copyright (C) 2019-2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Processable::Changes;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Path::Tiny;
+use Unicode::UTF8 qw(valid_utf8 decode_utf8 encode_utf8);
+
+use Lintian::Deb822;
+
+use Moo;
+use namespace::clean;
+
+with
+  'Lintian::Processable',
+  'Lintian::Processable::Fields::Files',
+  'Lintian::Processable::Changes::Overrides';
+
+=for Pod::Coverage BUILDARGS
+
+=head1 NAME
+
+Lintian::Processable::Changes -- A changes file Lintian can process
+
+=head1 SYNOPSIS
+
+ use Lintian::Processable::Changes;
+
+ my $processable = Lintian::Processable::Changes->new;
+ $processable->init_from_file('path');
+
+=head1 DESCRIPTION
+
+This class represents a 'changes' file that Lintian can process. Objects
+of this kind are often part of a L<Lintian::Group>, which
+represents all the files in a changes or buildinfo file.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item init_from_file (PATH)
+
+Initializes a new object from PATH.
+
+=cut
+
+sub init_from_file {
+    my ($self, $file) = @_;
+
+    croak encode_utf8("File $file does not exist")
+      unless -e $file;
+
+    $self->path($file);
+    $self->type('changes');
+
+    # dpkg will include news items in national encoding
+    my $bytes = path($self->path)->slurp;
+
+    my $contents;
+    if (valid_utf8($bytes)) {
+        $contents = decode_utf8($bytes);
+    } else {
+        # try to proceed with nat'l encoding; stopping here breaks tests
+        $contents = $bytes;
+    }
+
+    my $primary = Lintian::Deb822->new;
+    my @sections = $primary->parse_string($contents)
+      or croak encode_utf8(
+        $self->path. ' is not a valid '. $self->type . ' file');
+
+    $self->fields($sections[0]);
+
+    my $name = $self->fields->value('Source');
+    my $version = $self->fields->value('Version');
+    my $architecture = $self->fields->value('Architecture');
+
+    unless (length $name) {
+        $name = $self->guess_name($self->path);
+        croak encode_utf8('Cannot determine the name from ' . $self->path)
+          unless length $name;
+    }
+
+    my $source_name = $name;
+    my $source_version = $version;
+
+    $self->name($name);
+    $self->version($version);
+    $self->architecture($architecture);
+    $self->source_name($source_name);
+    $self->source_version($source_version);
+
+    # make sure none of these fields can cause traversal
+    $self->tainted(1)
+      if $self->name ne $name
+      || $self->version ne $version
+      || $self->architecture ne $architecture
+      || $self->source_name ne $source_name
+      || $self->source_version ne $source_version;
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+L<Lintian::Processable>
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Changes/Overrides.pm b/lib/Lintian/Processable/Changes/Overrides.pm
new file mode 100644
index 0000000..78bd04d
--- /dev/null
+++ b/lib/Lintian/Processable/Changes/Overrides.pm
@@ -0,0 +1,94 @@
+# -*- perl -*- Lintian::Processable::Changes::Overrides
+#
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Changes::Overrides;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo::Role;
+use namespace::clean;
+
+with 'Lintian::Processable::Overrides';
+
+=head1 NAME
+
+Lintian::Processable::Changes::Overrides - access to override data
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Changes::Overrides provides an interface for overrides.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item override_file
+
+=cut
+
+has override_file => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return undef;
+    }
+);
+
+=item overrides
+
+=cut
+
+has overrides => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my @overrides;
+
+        return \@overrides;
+    }
+);
+
+1;
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Debian/Control.pm b/lib/Lintian/Processable/Debian/Control.pm
new file mode 100644
index 0000000..a4c1cf9
--- /dev/null
+++ b/lib/Lintian/Processable/Debian/Control.pm
@@ -0,0 +1,90 @@
+# -*- perl -*-
+# Lintian::Processable::Debian::Control -- interface to source package data collection
+
+# Copyright (C) 2008 Russ Allbery
+# Copyright (C) 2009 Raphael Geissert
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Debian::Control;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::Debian::Control;
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::Debian::Control - Lintian interface to d/control fields
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Debian::Control provides an interface to package data
+from d/control.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item debian_control
+
+=cut
+
+has debian_control => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $control = Lintian::Debian::Control->new;
+
+        my $item = $self->patched->resolve_path('debian/control');
+        return $control
+          unless defined $item;
+
+        $control->load($item);
+
+        return $control;
+    }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Russ Allbery <rra@debian.org> for Lintian.
+Amended by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Diffstat.pm b/lib/Lintian/Processable/Diffstat.pm
new file mode 100644
index 0000000..82a3b28
--- /dev/null
+++ b/lib/Lintian/Processable/Diffstat.pm
@@ -0,0 +1,162 @@
+# -*- perl -*- Lintian::Processable::Diffstat -- access to collected diffstat data
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2019-2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Diffstat;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use IPC::Run3;
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8 decode_utf8);
+
+use Moo::Role;
+use namespace::clean;
+
+const my $COLON => q{:};
+const my $UNDERSCORE => q{_};
+const my $NEWLINE => qq{\n};
+
+const my $OPEN_PIPE => q{-|};
+const my $WAIT_STATUS_SHIFT => 8;
+
+=head1 NAME
+
+Lintian::Processable::Diffstat - access to collected diffstat data
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Diffstat provides an interface to diffstat data.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item diffstat
+
+Returns the path to diffstat output run on the Debian packaging diff
+(a.k.a. the "diff.gz") for 1.0 non-native packages.  For source
+packages without a "diff.gz" component, this returns the path to an
+empty file (this may be a device like /dev/null).
+
+=cut
+
+has diffstat => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $noepoch = $self->fields->value('Version');
+
+        # strip epoch
+        $noepoch =~ s/^\d://;
+
+        # look for a format 1.0 diff.gz near the input file
+        my $diffname = $self->name . $UNDERSCORE . $noepoch . '.diff.gz';
+        return {}
+          unless exists $self->files->{$diffname};
+
+        my $diffpath = path($self->path)->parent->child($diffname)->stringify;
+        return {}
+          unless -e $diffpath;
+
+        my @gunzip_command = ('gunzip', '--stdout', $diffpath);
+        my $gunzip_pid = open(my $from_gunzip, $OPEN_PIPE, @gunzip_command)
+          or die encode_utf8("Cannot run @gunzip_command: $!");
+
+        my $stdout;
+        my $stderr;
+        my @diffstat_command = qw(diffstat -p1);
+        run3(\@diffstat_command, $from_gunzip, \$stdout, \$stderr);
+        my $status = ($? >> $WAIT_STATUS_SHIFT);
+
+        $stdout = decode_utf8($stdout)
+          if length $stdout;
+        $stderr = decode_utf8($stderr)
+          if length $stderr;
+
+        if ($status) {
+
+            my $message= "Non-zero status $status from @diffstat_command";
+            $message .= $COLON . $NEWLINE . $stderr
+              if length $stderr;
+
+            die encode_utf8($message);
+        }
+
+        close $from_gunzip
+          or
+          warn encode_utf8("close failed for handle from @gunzip_command: $!");
+
+        waitpid($gunzip_pid, 0);
+
+        # remove summary in last line
+        chomp $stdout;
+        $stdout =~ s/.*\Z//;
+
+        my %diffstat;
+
+        my @lines = split(/\n/, $stdout);
+        for my $line (@lines) {
+
+            next
+              unless $line =~ s/\|\s*([^|]*)\s*$//;
+
+            my $stats = $1;
+            my $file = $line;
+
+            # trim both ends
+            $file =~ s/^\s+|\s+$//g;
+
+            die encode_utf8("syntax error in diffstat file: $line")
+              unless length $file;
+
+            $diffstat{$file} = $stats;
+        }
+
+        return \%diffstat;
+    }
+);
+
+1;
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Fields/Files.pm b/lib/Lintian/Processable/Fields/Files.pm
new file mode 100644
index 0000000..df21352
--- /dev/null
+++ b/lib/Lintian/Processable/Fields/Files.pm
@@ -0,0 +1,181 @@
+# -*- perl -*-
+# Lintian::Processable::Fields::Files -- interface to .buildinfo file data collection
+#
+# Copyright (C) 2010 Adam D. Barratt
+# Copyright (C) 2018 Chris Lamb
+# Copyright (C) 2019-2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Fields::Files;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::Fields::Files - Lintian interface to .buildinfo or changes file data collection
+
+=head1 SYNOPSIS
+
+   use Moo;
+
+   with 'Lintian::Processable::Fields::Files';
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Fields::Files provides an interface to data for .buildinfo
+and changes files.  It implements data collection methods specific to .buildinfo
+and changes files.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item files
+
+Returns a reference to a hash containing information about files listed
+in the .buildinfo file.  Each hash may have the following keys:
+
+=over 4
+
+=item name
+
+Name of the file.
+
+=item size
+
+The size of the file in bytes.
+
+=item section
+
+The archive section to which the file belongs.
+
+=item priority
+
+The priority of the file.
+
+=item checksums
+
+A hash with the keys being checksum algorithms and the values themselves being
+hashes containing
+
+=over 4
+
+=item sum
+
+The result of applying the given algorithm to the file.
+
+=item filesize
+
+The size of the file as given in the .buildinfo section relating to the given
+checksum.
+
+=back
+
+=back
+
+=cut
+
+has files => (
+    is => 'rw',
+    lazy => 1,
+    default =>
+
+      sub {
+        my ($self) = @_;
+
+        my %files;
+
+        my @files_lines = split(/\n/, $self->fields->value('Files'));
+
+        # trim both ends of each line
+        s/^\s+|\s+$//g for @files_lines;
+
+        for my $line (grep { length } @files_lines) {
+
+            my @fields = split(/\s+/, $line);
+            my $basename = $fields[-1];
+
+            # ignore traversals
+            next
+              if $basename =~ m{/};
+
+            my ($md5sum, $size, $section, $priority) = @fields;
+
+            $files{$basename}{checksums}{Md5} = {
+                'sum' => $md5sum,
+                'filesize' => $size,
+            };
+
+            $files{$basename}{name} = $basename;
+            $files{$basename}{size} = $size;
+
+            unless ($self->type eq 'source') {
+
+                $files{$basename}{section} = $section;
+                $files{$basename}{priority} = $priority;
+            }
+        }
+
+        for my $algorithm (qw(Sha1 Sha256)) {
+
+            my @lines
+              = split(/\n/, $self->fields->value("Checksums-$algorithm"));
+
+            # trim both ends of each line
+            s/^\s+|\s+$//g for @lines;
+
+            for my $line (grep { length } @lines) {
+
+                my ($checksum, $size, $basename) = split(/\s+/, $line);
+
+                # ignore traversals
+                next
+                  if $basename =~ m{/};
+
+                $files{$basename}{checksums}{$algorithm} = {
+                    'sum' => $checksum,
+                    'filesize' => $size
+                };
+            }
+        }
+
+        return \%files;
+    }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Adam D. Barratt <adsb@debian.org> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1), L<Lintian::Processable>
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Hardening.pm b/lib/Lintian/Processable/Hardening.pm
new file mode 100644
index 0000000..4bf24bd
--- /dev/null
+++ b/lib/Lintian/Processable/Hardening.pm
@@ -0,0 +1,105 @@
+# -*- perl -*- Lintian::Processable::Hardening
+#
+# Copyright (C) 2019 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Hardening;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::Hardening - access to collected hardening data
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Hardening provides an interface to collected hardening data.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item hardening_info
+
+Returns a hashref mapping a FILE to its hardening issues.
+
+NB: This is generally only useful for checks/binaries to emit the
+hardening-no-* tags.
+
+=cut
+
+sub hardening_info {
+    my ($self) = @_;
+
+    return $self->{hardening_info}
+      if exists $self->{hardening_info};
+
+    my $hardf = path($self->basedir)->child('hardening-info')->stringify;
+
+    my %hardening_info;
+
+    if (-e $hardf) {
+        open(my $idx, '<:utf8_strict', $hardf)
+          or die encode_utf8("Cannot open $hardf");
+
+        while (my $line = <$idx>) {
+            chomp($line);
+
+            if ($line =~ m{^([^:]+):(?:\./)?(.*)$}) {
+                my ($tag, $file) = ($1, $2);
+
+                push(@{$hardening_info{$file}}, $tag);
+            }
+        }
+        close($idx);
+    }
+
+    $self->{hardening_info} = \%hardening_info;
+
+    return $self->{hardening_info};
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Installable.pm b/lib/Lintian/Processable/Installable.pm
new file mode 100644
index 0000000..54ae406
--- /dev/null
+++ b/lib/Lintian/Processable/Installable.pm
@@ -0,0 +1,201 @@
+# Copyright (C) 2019-2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Processable::Installable;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use IPC::Run3;
+use Unicode::UTF8 qw(encode_utf8 decode_utf8 valid_utf8);
+
+use Lintian::Deb822;
+
+use Moo;
+use namespace::clean;
+
+with
+  'Lintian::Processable',
+  'Lintian::Processable::Installable::Changelog',
+  'Lintian::Processable::Installable::Class',
+  'Lintian::Processable::Installable::Conffiles',
+  'Lintian::Processable::Installable::Control',
+  'Lintian::Processable::Installable::Installed',
+  'Lintian::Processable::Installable::Overrides',
+  'Lintian::Processable::Installable::Relation',
+  'Lintian::Processable::IsNonFree',
+  'Lintian::Processable::Hardening',
+  'Lintian::Processable::NotJustDocs';
+
+# read up to 40kB at a time.  this happens to be 4096 "tar records"
+# (with a block-size of 512 and a block factor of 20, which appear to
+# be the defaults).  when we do full reads and writes of READ_SIZE (the
+# OS willing), the receiving end will never be with an incomplete
+# record.
+const my $TAR_RECORD_SIZE => 20 * 512;
+
+const my $COLON => q{:};
+const my $NEWLINE => qq{\n};
+const my $OPEN_PIPE => q{-|};
+
+const my $WAIT_STATUS_SHIFT => 8;
+
+=for Pod::Coverage BUILDARGS
+
+=head1 NAME
+
+Lintian::Processable::Installable -- An installation package Lintian can process
+
+=head1 SYNOPSIS
+
+ use Lintian::Processable::Installable;
+
+ my $processable = Lintian::Processable::Installable->new;
+ $processable->init_from_file('path');
+
+=head1 DESCRIPTION
+
+This class represents a 'deb' or 'udeb' file that Lintian can process. Objects
+of this kind are often part of a L<Lintian::Group>, which
+represents all the files in a changes or buildinfo file.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item init_from_file (PATH)
+
+Initializes a new object from PATH.
+
+=cut
+
+sub init_from_file {
+    my ($self, $file) = @_;
+
+    croak encode_utf8("File $file does not exist")
+      unless -e $file;
+
+    $self->path($file);
+
+    # get control.tar.gz; dpkg-deb -f $file is slow; use tar instead
+    my @dpkg_command = ('dpkg-deb', '--ctrl-tarfile', $self->path);
+
+    my $dpkg_pid = open(my $from_dpkg, $OPEN_PIPE, @dpkg_command)
+      or die encode_utf8("Cannot run @dpkg_command: $!");
+
+    # would like to set buffer size to 4096 & $TAR_RECORD_SIZE
+
+    # get binary control file
+    my $stdout_bytes;
+    my $stderr_bytes;
+    my @tar_command = qw{tar --wildcards -xO -f - *control};
+    run3(\@tar_command, $from_dpkg, \$stdout_bytes, \$stderr_bytes);
+    my $status = ($? >> $WAIT_STATUS_SHIFT);
+
+    if ($status) {
+
+        my $message= "Non-zero status $status from @tar_command";
+        $message .= $COLON . $NEWLINE . decode_utf8($stderr_bytes)
+          if length $stderr_bytes;
+
+        croak encode_utf8($message);
+    }
+
+    close $from_dpkg
+      or warn encode_utf8("close failed for handle from @dpkg_command: $!");
+
+    waitpid($dpkg_pid, 0);
+
+    croak encode_utf8('Nationally encoded control data in ' . $self->path)
+      unless valid_utf8($stdout_bytes);
+
+    my $stdout = decode_utf8($stdout_bytes);
+
+    my $deb822 = Lintian::Deb822->new;
+    my @sections = $deb822->parse_string($stdout);
+    croak encode_utf8(
+        'Not exactly one section with installable control data in '
+          . $self->path)
+      unless @sections == 1;
+
+    $self->fields($sections[0]);
+
+    my $name = $self->fields->value('Package');
+    my $version = $self->fields->value('Version');
+    my $architecture = $self->fields->value('Architecture');
+    my $source_name = $self->fields->value('Source');
+
+    my $source_version = $version;
+
+    unless (length $name) {
+        $name = $self->guess_name($self->path);
+        croak encode_utf8('Cannot determine the name from ' . $self->path)
+          unless length $name;
+    }
+
+    # source may be left out if same as $name
+    $source_name = $name
+      unless length $source_name;
+
+    # source probably contains the version in parentheses
+    if ($source_name =~ m/(\S++)\s*\(([^\)]+)\)/){
+        $source_name = $1;
+        $source_version = $2;
+    }
+
+    $self->name($name);
+    $self->version($version);
+    $self->architecture($architecture);
+    $self->source_name($source_name);
+    $self->source_version($source_version);
+
+    # make sure none of these fields can cause traversal
+    $self->tainted(1)
+      if $self->name ne $name
+      || $self->version ne $version
+      || $self->architecture ne $architecture
+      || $self->source_name ne $source_name
+      || $self->source_version ne $source_version;
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+L<Lintian::Processable>
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Installable/Changelog.pm b/lib/Lintian/Processable/Installable/Changelog.pm
new file mode 100644
index 0000000..c43a17b
--- /dev/null
+++ b/lib/Lintian/Processable/Installable/Changelog.pm
@@ -0,0 +1,151 @@
+# -*- perl -*- Lintian::Processable::Installable::Changelog -- access to collected changelog data
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2019-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Installable::Changelog;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use File::Copy qw(copy);
+use List::SomeUtils qw(first_value);
+use Path::Tiny;
+use Unicode::UTF8 qw(valid_utf8 decode_utf8 encode_utf8);
+
+use Lintian::IPC::Run3 qw(safe_qx);
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::Installable::Changelog - access to collected changelog data
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Installable::Changelog provides an interface to changelog data.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item changelog_item
+
+=cut
+
+has changelog_item => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my @candidate_names = (
+            'changelog.Debian.gz','changelog.Debian',
+            'changelog.debian.gz','changelog.debian',
+            'changelog.gz','changelog',
+        );
+
+        my $package_path = 'usr/share/doc/' . $self->name;
+        my @candidate_items = grep { defined }
+          map { $self->installed->lookup("$package_path/$_") }@candidate_names;
+
+        # pick the first existing file
+        my $item
+          = first_value { $_->is_file || length $_->link } @candidate_items;
+
+        return $item;
+    }
+);
+
+=item changelog
+
+For binary:
+
+Returns the changelog of the binary package as a Parse::DebianChangelog
+object, or an empty object if the changelog doesn't exist.  The changelog-file
+collection script must have been run to create the changelog file, which
+this method expects to find in F<changelog>.
+
+=cut
+
+has changelog => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $changelog = Lintian::Changelog->new;
+
+        my $unresolved = $self->changelog_item;
+        return $changelog
+          unless defined $unresolved;
+
+        # stop for dangling symbolic link
+        my $item = $unresolved->resolve_path;
+        return $changelog
+          unless defined $item;
+
+        # return empty changelog
+        return $changelog
+          unless $item->is_file && $item->is_open_ok;
+
+        if ($item->basename =~ m{ [.]gz $}x) {
+
+            my $bytes = safe_qx('gunzip', '-c', $item->unpacked_path);
+
+            return $changelog
+              unless valid_utf8($bytes);
+
+            $changelog->parse(decode_utf8($bytes));
+
+            return $changelog;
+        }
+
+        return $changelog
+          unless $item->is_valid_utf8;
+
+        $changelog->parse($item->decoded_utf8);
+
+        return $changelog;
+    }
+);
+
+1;
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Installable/Class.pm b/lib/Lintian/Processable/Installable/Class.pm
new file mode 100644
index 0000000..00520be
--- /dev/null
+++ b/lib/Lintian/Processable/Installable/Class.pm
@@ -0,0 +1,139 @@
+# -*- perl -*-
+# Lintian::Processable::Installable::Class -- interface to binary package data collection
+
+# Copyright (C) 2008, 2009 Russ Allbery
+# Copyright (C) 2008 Frank Lichtenheld
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Installable::Class;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::Installable::Class - Lintian interface to binary package data collection
+
+=head1 SYNOPSIS
+
+    my ($name, $type, $dir) = ('foobar', 'binary', '/path/to/lab-entry');
+    my $collect = Lintian::Processable::Installable::Class->new($name);
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Installable::Class provides an interface to package data for binary
+packages.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item is_debug_package
+
+The package probably contains only debug symbols.
+
+=cut
+
+sub is_debug_package {
+    my ($self) = @_;
+
+    return 1
+      if $self->name =~ /-dbg(?:sym)?/;
+
+    return 0;
+}
+
+=item is_auto_generated
+
+The package was probably generated automatically.
+
+=cut
+
+sub is_auto_generated {
+    my ($self) = @_;
+
+    return 1
+      if $self->fields->declares('Auto-Built-Package');
+
+    return 0;
+}
+
+=item is_transitional
+
+The package is probably transitional, i.e. it probably depends
+ on stuff will eventually disappear.
+
+=cut
+
+sub is_transitional {
+    my ($self) = @_;
+
+    return 1
+      if $self->fields->value('Description') =~ /transitional package/i;
+
+    return 0;
+}
+
+=item is_meta_package
+
+This package is probably some kind of meta or task package.  A meta
+package is usually empty and just depend on stuff.  It also returns
+a true value for "tasks" (i.e. tasksel "tasks").
+
+=cut
+
+sub is_meta_package {
+    my ($self) = @_;
+
+    return 1
+      if $self->fields->value('Description')
+      =~ /meta[ -]?package|(?:dependency|dummy|empty) package/i;
+
+    # section "tasks" or "metapackages" qualifies too
+    return 1
+      if $self->fields->value('Section') =~ m{(?:^|/)(?:tasks|metapackages)$};
+
+    return 1
+      if $self->name =~ /^task-/;
+
+    return 0;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Frank Lichtenheld <djpig@debian.org> for Lintian.
+Amended by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Installable/Conffiles.pm b/lib/Lintian/Processable/Installable/Conffiles.pm
new file mode 100644
index 0000000..50db7f7
--- /dev/null
+++ b/lib/Lintian/Processable/Installable/Conffiles.pm
@@ -0,0 +1,97 @@
+# -*- perl -*- Lintian::Processable::Installable::Conffiles
+#
+# Copyright (C) 2019-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Installable::Conffiles;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::Conffiles;
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::Installable::Conffiles - access to collected control data for conffiles
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Installable::Conffiles provides an interface to control data for conffiles.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item conffiles_item
+
+=cut
+
+has conffiles_item => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return $self->control->resolve_path('conffiles');
+    }
+);
+
+=item declared_conffiles
+
+=cut
+
+has declared_conffiles => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $item = $self->conffiles_item;
+
+        my $conffiles = Lintian::Conffiles->new;
+        $conffiles->parse($item, $self);
+
+        return $conffiles;
+    }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Installable/Control.pm b/lib/Lintian/Processable/Installable/Control.pm
new file mode 100644
index 0000000..b6a72d8
--- /dev/null
+++ b/lib/Lintian/Processable/Installable/Control.pm
@@ -0,0 +1,99 @@
+# -*- perl -*- Lintian::Processable::Installable::Control
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Installable::Control;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(uniq);
+
+use Lintian::Index;
+
+const my $SLASH => q{/};
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::Installable::Control - access to collected control file data
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Installable::Control provides an interface to control file data.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item control
+
+Returns the index for a binary control file.
+
+=cut
+
+has control => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $index = Lintian::Index->new;
+        my $archive = $self->basename;
+        $index->identifier("$archive (control)");
+        $index->basedir($self->basedir . $SLASH . 'control');
+
+        # control files are not installed relative to the system root
+        # disallow absolute paths and symbolic links
+
+        my @command = (qw(dpkg-deb --ctrl-tarfile), $self->path);
+        my $errors = $index->create_from_piped_tar(\@command);
+
+        my @messages = uniq split(/\n/, $errors);
+        push(@{$index->unpack_messages}, @messages);
+
+        return $index;
+    }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Installable/Installed.pm b/lib/Lintian/Processable/Installable/Installed.pm
new file mode 100644
index 0000000..61444ac
--- /dev/null
+++ b/lib/Lintian/Processable/Installable/Installed.pm
@@ -0,0 +1,103 @@
+# -*- perl -*- Lintian::Processable::Installable::Installed
+#
+# Copyright (C) 2008, 2009 Russ Allbery
+# Copyright (C) 2008 Frank Lichtenheld
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Installable::Installed;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(uniq);
+
+use Lintian::Index;
+
+const my $SLASH => q{/};
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::Installable::Installed - access to collected data about the upstream (orig) sources
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Installable::Installed provides an interface to collected data about the upstream (orig) sources.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item installed
+
+Returns a index object representing installed files from a binary package.
+
+=cut
+
+has installed => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $index = Lintian::Index->new;
+        my $archive = $self->basename;
+        $index->identifier("$archive (installed)");
+        $index->basedir($self->basedir . $SLASH . 'unpacked');
+
+        # binary packages are anchored to the system root
+        # allow absolute paths and symbolic links
+        $index->anchored(1);
+
+        my @command = (qw(dpkg-deb --fsys-tarfile), $self->path);
+        my $errors = $index->create_from_piped_tar(\@command);
+
+        my @messages = uniq split(/\n/, $errors);
+        push(@{$index->unpack_messages}, @messages);
+
+        return $index;
+    }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Installable/Overrides.pm b/lib/Lintian/Processable/Installable/Overrides.pm
new file mode 100644
index 0000000..0da551f
--- /dev/null
+++ b/lib/Lintian/Processable/Installable/Overrides.pm
@@ -0,0 +1,131 @@
+# -*- perl -*- Lintian::Processable::Installable::Overrides
+#
+# Copyright (C) 2019-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Installable::Overrides;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use PerlIO::gzip;
+use List::SomeUtils qw(first_value);
+use Unicode::UTF8 qw(valid_utf8 decode_utf8 encode_utf8);
+
+use Moo::Role;
+use namespace::clean;
+
+with 'Lintian::Processable::Overrides';
+
+const my $EMPTY => q{};
+
+=head1 NAME
+
+Lintian::Processable::Installable::Overrides - access to override data
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Installable::Overrides provides an interface for overrides.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item override_file
+
+=cut
+
+has override_file => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $unzipped = 'usr/share/lintian/overrides/' . $self->name;
+
+        my @candidates = map { $unzipped . $_ } ($EMPTY, '.gz');
+
+        # pick the first
+        my $override_item= first_value { defined }
+        map { $self->installed->lookup($_) } @candidates;
+
+        return $override_item;
+    }
+);
+
+=item overrides
+
+=cut
+
+has overrides => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return []
+          unless defined $self->override_file;
+
+        my $contents = $EMPTY;
+
+        if ($self->override_file->name =~ m{ [.]gz $}x) {
+
+            my $local_path = $self->override_file->unpacked_path;
+
+            open(my $fd, '<:gzip', $local_path)
+              or die encode_utf8("Cannot open $local_path.");
+
+            local $/ = undef;
+            my $bytes = <$fd>;
+
+            $contents = decode_utf8($bytes)
+              if valid_utf8($bytes);
+
+            close $fd;
+
+        } else {
+            $contents = $self->override_file->decoded_utf8;
+        }
+
+        return $self->parse_overrides($contents);
+    }
+);
+
+1;
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Installable/Relation.pm b/lib/Lintian/Processable/Installable/Relation.pm
new file mode 100644
index 0000000..ac94489
--- /dev/null
+++ b/lib/Lintian/Processable/Installable/Relation.pm
@@ -0,0 +1,154 @@
+# -*- perl -*-
+# Lintian::Processable::Installable::Relation -- interface to binary package data collection
+
+# Copyright (C) 2008, 2009 Russ Allbery
+# Copyright (C) 2008 Frank Lichtenheld
+# Copyright (C) 2012 Kees Cook
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Installable::Relation;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Relation;
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::Installable::Relation - Lintian interface to binary package data collection
+
+=head1 SYNOPSIS
+
+    my ($name, $type, $dir) = ('foobar', 'binary', '/path/to/lab-entry');
+    my $collect = Lintian::Processable::Installable::Relation->new($name);
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Installable::Relation provides an interface to package data for binary
+packages.  It implements data collection methods specific to binary
+packages.
+
+This module is in its infancy.  Most of Lintian still reads all data from
+files in the laboratory whenever that data is needed and generates that
+data via collect scripts.  The goal is to eventually access all data about
+binary packages via this module so that the module can cache data where
+appropriate and possibly retire collect scripts in favor of caching that
+data in memory.
+
+Native heuristics are only available in source packages.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item relation (FIELD)
+
+Returns a L<Lintian::Relation> object for the specified FIELD, which should
+be one of the possible relationship fields of a Debian package or one of
+the following special values:
+
+=over 4
+
+=item All
+
+The concatenation of Pre-Depends, Depends, Recommends, and Suggests.
+
+=item Strong
+
+The concatenation of Pre-Depends and Depends.
+
+=item Weak
+
+The concatenation of Recommends and Suggests.
+
+=back
+
+If FIELD isn't present in the package, the returned Lintian::Relation
+object will be empty (always present and satisfies nothing).
+
+=item saved_relations
+
+=cut
+
+has saved_relations => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+my %alias = (
+    all    => [qw(Pre-Depends Depends Recommends Suggests)],
+    strong => [qw(Pre-Depends Depends)],
+    weak   => [qw(Recommends Suggests)]
+);
+
+my %known = map { $_ => 1 }
+  qw(pre-depends depends recommends suggests enhances breaks
+  conflicts provides replaces);
+
+sub relation {
+    my ($self, $name) = @_;
+
+    my $lowercase = lc $name;
+
+    my $relation = $self->saved_relations->{$lowercase};
+    unless (defined $relation) {
+
+        if (exists $alias{$lowercase}) {
+            $relation
+              = Lintian::Relation->new->logical_and(map { $self->relation($_) }
+                  @{ $alias{$lowercase} });
+        } else {
+            croak encode_utf8("unknown relation field $name")
+              unless $known{$lowercase};
+
+            my $value = $self->fields->value($name);
+            $relation = Lintian::Relation->new->load($value);
+        }
+
+        $self->saved_relations->{$lowercase} = $relation;
+    }
+
+    return $relation;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Frank Lichtenheld <djpig@debian.org> for Lintian.
+Amended by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/IsNonFree.pm b/lib/Lintian/Processable/IsNonFree.pm
new file mode 100644
index 0000000..bd6f246
--- /dev/null
+++ b/lib/Lintian/Processable/IsNonFree.pm
@@ -0,0 +1,109 @@
+# -*- perl -*-
+# Lintian::Processable::IsNonFree -- interface to source package data collection
+
+# Copyright (C) 2008 Russ Allbery
+# Copyright (C) 2009 Raphael Geissert
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::IsNonFree;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::IsNonFree - Lintian interface to source package data collection
+
+=head1 SYNOPSIS
+
+    my ($name, $type, $dir) = ('foobar', 'source', '/path/to/lab-entry');
+    my $collect = Lintian::Processable::IsNonFree->new($name);
+    if ($collect->native) {
+        print encode_utf8("Package is native\n");
+    }
+
+=head1 DESCRIPTION
+
+Lintian::Processable::IsNonFree provides an interface to package data for source
+packages.  It implements data collection methods specific to source
+packages.
+
+This module is in its infancy.  Most of Lintian still reads all data from
+files in the laboratory whenever that data is needed and generates that
+data via collect scripts.  The goal is to eventually access all data about
+source packages via this module so that the module can cache data where
+appropriate and possibly retire collect scripts in favor of caching that
+data in memory.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item is_non_free
+
+Returns a truth value if the package appears to be non-free (based on
+the section field; "non-free/*" and "restricted/*")
+
+=cut
+
+has is_non_free => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $section;
+
+        if ($self->type eq 'source') {
+            $section = $self->debian_control->source_fields->value('Section');
+        } else {
+            $section = $self->fields->value('Section');
+        }
+
+        $section ||= 'main';
+
+        return 1
+          if $section
+          =~ m{^(?:non-free|non-free-firmware|restricted|multiverse)/};
+
+        return 0;
+    }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Russ Allbery <rra@debian.org> for Lintian.
+Amended by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/NotJustDocs.pm b/lib/Lintian/Processable/NotJustDocs.pm
new file mode 100644
index 0000000..1e08760
--- /dev/null
+++ b/lib/Lintian/Processable/NotJustDocs.pm
@@ -0,0 +1,112 @@
+# -*- perl -*-
+# Lintian::Processable::NotJustDocs
+
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::NotJustDocs;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::NotJustDocs - Lintian interface to installable package data collection
+
+=head1 SYNOPSIS
+
+    my $processable = Lintian::Processable::Installable->new;
+
+    my $is_empty = $processable->not_just_docs;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::NotJustDocs provides an interface to package data for installation
+packages.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item not_just_docs
+
+Returns a truth value if the package appears to be empty.
+
+=cut
+
+has not_just_docs => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $quoted_name = quotemeta($self->name);
+
+        my $empty = 1;
+        for my $item (@{$self->installed->sorted_list}) {
+
+            # ignore directories
+            next
+              if $item->is_dir;
+
+            # skip /usr/share/doc/$name symlinks.
+            next
+              if $item->name eq 'usr/share/doc/' . $self->name;
+
+            # only look outside /usr/share/doc/$name directory
+            next
+              if $item->name =~ m{^usr/share/doc/$quoted_name};
+
+            # except if it is a lintian override.
+            next
+              if $item->name =~ m{\A
+                             # Except for:
+                             usr/share/ (?:
+                                 # lintian overrides
+                                 lintian/overrides/$quoted_name(?:\.gz)?
+                                 # reportbug scripts/utilities
+                             | bug/$quoted_name(?:/(?:control|presubj|script))?
+                             )\Z}xsm;
+
+            return 0;
+        }
+
+        return 1;
+    }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Overrides.pm b/lib/Lintian/Processable/Overrides.pm
new file mode 100644
index 0000000..0de05a4
--- /dev/null
+++ b/lib/Lintian/Processable/Overrides.pm
@@ -0,0 +1,219 @@
+# -*- perl -*- Lintian::Processable::Overrides
+#
+# Copyright (C) 2019-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Overrides;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Lintian::Override;
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::Overrides - access to override data
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Overrides provides an interface to overrides.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item override_errors
+
+=cut
+
+has override_errors => (is => 'rw', default => sub { [] });
+
+=item parse_overrides
+
+=cut
+
+sub parse_overrides {
+    my ($self, $contents) = @_;
+
+    $contents //= $EMPTY;
+
+    my @declared_overrides;
+
+    my $justification = $EMPTY;
+    my $previous = Lintian::Override->new;
+
+    my @lines = split(/\n/, $contents);
+
+    my $position = 1;
+    for my $line (@lines) {
+
+        my $remaining = $line;
+
+        # trim both ends
+        $remaining =~ s/^\s+|\s+$//g;
+
+        if ($remaining eq $EMPTY) {
+            # Throw away comments, as they are not attached to a tag
+            # also throw away the option of "carrying over" the last
+            # comment
+            $justification = $EMPTY;
+            $previous = Lintian::Override->new;
+            next;
+        }
+
+        if ($remaining =~ s{^ [#] \s* }{}x) {
+
+            if (length $remaining) {
+
+                $justification .= $SPACE
+                  if length $justification;
+
+                $justification .= $remaining;
+            }
+
+            next;
+        }
+
+        # reduce white space
+        $remaining =~ s/\s+/ /g;
+
+        # [[pkg-name] [arch-list] [pkg-type]:] <tag> [context]
+        my $require_colon = 0;
+        my @architectures;
+
+        # strip package name, if present; require name
+        # parsing overrides is ambiguous (see #699628)
+        my $package = $self->name;
+        if ($remaining =~ s/^\Q$package\E(?=\s|:)//) {
+
+            # both spaces or colon were unmatched lookhead
+            $remaining =~ s/^\s+//;
+            $require_colon = 1;
+        }
+
+        # remove architecture list
+        if ($remaining =~ s{^ \[ ([^\]]*) \] (?=\s|:)}{}x) {
+
+            my $list = $1;
+
+            @architectures = split($SPACE, $list);
+
+            # both spaces or colon were unmatched lookhead
+            $remaining =~ s/^\s+//;
+            $require_colon = 1;
+        }
+
+        # remove package type
+        my $type = $self->type;
+        if ($remaining =~ s/^\Q$type\E(?=\s|:)//) {
+
+            # both spaces or colon were unmatched lookhead
+            $remaining =~ s/^\s+//;
+            $require_colon = 1;
+        }
+
+        my $pointer = $self->override_file->pointer($position);
+
+        # require and remove colon when any package details are present
+        if ($require_colon && $remaining !~ s/^\s*:\s*//) {
+
+            my %error;
+            $error{message} = 'Expected a colon';
+            $error{pointer} = $pointer;
+            push(@{$self->override_errors}, \%error);
+
+            next;
+        }
+
+        my $hint_like = $remaining;
+
+        my ($tag_name, $pattern) = split($SPACE, $hint_like, 2);
+
+        if (!length $tag_name) {
+
+            my %error;
+            $error{message} = "Cannot parse line: $line";
+            $error{pointer} = $pointer;
+            push(@{$self->override_errors}, \%error);
+
+            next;
+        }
+
+        $pattern //= $EMPTY;
+
+        # There are no new comments, no "empty line" in between and
+        # this tag is the same as the last, so we "carry over" the
+        # comment from the previous override (if any).
+        $justification = $previous->justification
+          if !length $justification
+          && $tag_name eq $previous->tag_name;
+
+        my $current = Lintian::Override->new;
+
+        $current->tag_name($tag_name);
+        $current->architectures(\@architectures);
+        $current->pattern($pattern);
+        $current->position($position);
+
+        # combine successive white space
+        $justification =~ s{ \s+ }{ }gx;
+
+        $current->justification($justification);
+        $justification = $EMPTY;
+
+        push(@declared_overrides, $current);
+
+        $previous = $current;
+
+    } continue {
+        $position++;
+    }
+
+    return \@declared_overrides;
+}
+
+1;
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Source.pm b/lib/Lintian/Processable/Source.pm
new file mode 100644
index 0000000..e4dc001
--- /dev/null
+++ b/lib/Lintian/Processable/Source.pm
@@ -0,0 +1,142 @@
+# Copyright (C) 2019-2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Processable::Source;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use File::Spec;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Deb822;
+
+use Moo;
+use namespace::clean;
+
+with
+  'Lintian::Processable',
+  'Lintian::Processable::Diffstat',
+  'Lintian::Processable::Changelog::Version',
+  'Lintian::Processable::Debian::Control',
+  'Lintian::Processable::Fields::Files',
+  'Lintian::Processable::IsNonFree',
+  'Lintian::Processable::Source::Changelog',
+  'Lintian::Processable::Source::Components',
+  'Lintian::Processable::Source::Format',
+  'Lintian::Processable::Source::Orig',
+  'Lintian::Processable::Source::Overrides',
+  'Lintian::Processable::Source::Patched',
+  'Lintian::Processable::Source::Relation',
+  'Lintian::Processable::Source::Repacked';
+
+=for Pod::Coverage BUILDARGS
+
+=head1 NAME
+
+Lintian::Processable::Source -- A dsc source package Lintian can process
+
+=head1 SYNOPSIS
+
+ use Lintian::Processable::Source;
+
+ my $processable = Lintian::Processable::Source->new;
+ $processable->init_from_file('path');
+
+=head1 DESCRIPTION
+
+This class represents a 'dsc' file that Lintian can process. Objects
+of this kind are often part of a L<Lintian::Group>, which
+represents all the files in a changes or buildinfo file.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item init_from_file (PATH)
+
+Initializes a new object from PATH.
+
+=cut
+
+sub init_from_file {
+    my ($self, $file) = @_;
+
+    croak encode_utf8("File $file does not exist")
+      unless -e $file;
+
+    $self->path($file);
+    $self->type('source');
+
+    my $primary = Lintian::Deb822->new;
+    my @sections = $primary->read_file($self->path)
+      or croak encode_utf8($self->path . ' is not valid dsc file');
+
+    $self->fields($sections[0]);
+
+    my $name = $self->fields->value('Source');
+    my $version = $self->fields->value('Version');
+    my $architecture = 'source';
+
+    # it is its own source package
+    my $source_name = $name;
+    my $source_version = $version;
+
+    croak encode_utf8($self->path . ' is missing Source field')
+      unless length $name;
+
+    $self->name($name);
+    $self->version($version);
+    $self->architecture($architecture);
+    $self->source_name($source_name);
+    $self->source_version($source_version);
+
+    # make sure none of these fields can cause traversal
+    $self->tainted(1)
+      if $self->name ne $name
+      || $self->version ne $version
+      || $self->architecture ne $architecture
+      || $self->source_name ne $source_name
+      || $self->source_version ne $source_version;
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+L<Lintian::Processable>
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Source/Changelog.pm b/lib/Lintian/Processable/Source/Changelog.pm
new file mode 100644
index 0000000..a781057
--- /dev/null
+++ b/lib/Lintian/Processable/Source/Changelog.pm
@@ -0,0 +1,109 @@
+# -*- perl -*- Lintian::Processable::Source::Changelog -- access to collected changelog data
+#
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2019-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Source::Changelog;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::Source::Changelog - access to collected changelog data
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Source::Changelog provides an interface to changelog data.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item changelog_item
+
+=cut
+
+has changelog_item => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $item = $self->patched->resolve_path('debian/changelog');
+
+        return $item;
+    }
+);
+
+=item changelog
+
+Returns the changelog of the source package as a Parse::DebianChangelog
+object, or an empty object if the changelog cannot be resolved safely.
+
+=cut
+
+has changelog => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $changelog = Lintian::Changelog->new;
+
+        my $item = $self->changelog_item;
+
+        # return empty changelog
+        return $changelog
+          unless defined $item && $item->is_open_ok;
+
+        return $changelog
+          unless $item->is_valid_utf8;
+
+        $changelog->parse($item->decoded_utf8);
+
+        return $changelog;
+    }
+);
+
+1;
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Source/Components.pm b/lib/Lintian/Processable/Source/Components.pm
new file mode 100644
index 0000000..1541abe
--- /dev/null
+++ b/lib/Lintian/Processable/Source/Components.pm
@@ -0,0 +1,126 @@
+# -*- perl -*-
+# Lintian::Processable::Source::Components -- interface to orig tag components
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Source::Components;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo::Role;
+use namespace::clean;
+
+const my $EMPTY => q{};
+
+=head1 NAME
+
+Lintian::Processable::Source::Components - interface to orig tar components
+
+=head1 SYNOPSIS
+
+   use Moo;
+
+   with 'Lintian::Processable::Source::Components';
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Source::Components provides an interface to data for
+upstream source components. Most sources only use one tarball.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item components
+
+Returns a reference to a hash containing information about source components
+listed in the .dsc file.  The key is the filename, and the value is the name
+of the component.
+
+=cut
+
+has components => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        # determine source and version; handle missing fields
+        my $name = $self->fields->value('Source');
+        my $version = $self->fields->value('Version');
+        my $architecture = 'source';
+
+        # it is its own source package
+        my $source = $name;
+        my $source_version = $version;
+
+        # version handling based on Dpkg::Version::parseversion.
+        my $noepoch = $source_version;
+        if ($noepoch =~ /:/) {
+            $noepoch =~ s/^(?:\d+):(.+)/$1/
+              or die encode_utf8("Bad version number '$noepoch'");
+        }
+
+        my $baserev = $source . '_' . $noepoch;
+
+        # strip debian revision
+        $noepoch =~ s/(.+)-(?:.*)$/$1/;
+        my $base = $source . '_' . $noepoch;
+
+        my $files = $self->files;
+
+        my %components;
+        for my $name (keys %{$files}) {
+
+            # Look for $pkg_$version.orig(-$comp)?.tar.$ext (non-native)
+            #       or $pkg_$version.tar.$ext (native)
+            #  - This deliberately does not look for the debian packaging
+            #    even when this would be a tarball.
+            if ($name
+                =~ /^(?:\Q$base\E\.orig(?:-(.*))?|\Q$baserev\E)\.tar\.(?:gz|bz2|lzma|xz)$/
+            ) {
+                $components{$name} = $1 // $EMPTY;
+            }
+        }
+
+        return \%components;
+    }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Adam D. Barratt <adsb@debian.org> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1), L<Lintian::Processable>
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Source/Format.pm b/lib/Lintian/Processable/Source/Format.pm
new file mode 100644
index 0000000..551f93e
--- /dev/null
+++ b/lib/Lintian/Processable/Source/Format.pm
@@ -0,0 +1,136 @@
+# -*- perl -*-
+# Lintian::Processable::Source::Format -- interface to source package data collection
+
+# Copyright (C) 2008 Russ Allbery
+# Copyright (C) 2009 Raphael Geissert
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Source::Format;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Path::Tiny;
+
+use Moo::Role;
+use namespace::clean;
+
+const my $UNDERSCORE => q{_};
+
+=head1 NAME
+
+Lintian::Processable::Source::Format - Lintian interface to source format
+
+=head1 SYNOPSIS
+
+    my $collect = Lintian::Processable::Source::Format->new;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Source::Format provides an interface to source format
+information.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item source_format
+
+=cut
+
+has source_format => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $format = $self->fields->value('Format') || '1.0';
+
+        return $format;
+    }
+);
+
+=item native
+
+Returns true if the source package is native and false otherwise.
+This is generally determined from the source format, though in the 1.0
+case the nativeness is determined by looking for the diff.gz (using
+the name of the source package and its version).
+
+If the source format is 1.0 and the version number is absent, this
+will return false (as native packages are a lot rarer than non-native
+ones).
+
+Note if the source format is missing, it is assumed to be a 1.0
+package.
+
+=cut
+
+has native => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $format = $self->source_format;
+
+        return 0
+          if $format =~ /^\s*2\.0\s*$/;
+
+        return 0
+          if $format =~ /^\s*3\.0\s+\(quilt|git\)\s*$/;
+
+        return 1
+          if $format =~ /^\s*3\.0\s+\(native\)\s*$/;
+
+        my $version = $self->fields->value('Version');
+        return 0
+          unless length $version;
+
+        # strip epoch
+        $version =~ s/^\d+://;
+
+        my $diffname = $self->name . $UNDERSCORE . "$version.diff.gz";
+
+        return 0
+          if exists $self->files->{$diffname};
+
+        return 1;
+    }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Russ Allbery <rra@debian.org> for Lintian.
+Amended by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1), Lintian::Relation(3)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Source/Orig.pm b/lib/Lintian/Processable/Source/Orig.pm
new file mode 100644
index 0000000..dd263f5
--- /dev/null
+++ b/lib/Lintian/Processable/Source/Orig.pm
@@ -0,0 +1,200 @@
+# -*- perl -*- Lintian::Processable::Source::Orig
+#
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Source::Orig;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use List::SomeUtils qw(uniq);
+use List::UtilsBy qw(sort_by);
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Index;
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::Source::Orig - access to collected data about the upstream (orig) sources
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Source::Orig provides an interface to collected data about the upstream (orig) sources.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item orig
+
+Returns the index for orig.tar.gz.
+
+=cut
+
+my %DECOMPRESS_COMMAND = (
+    'gz' => 'gzip --decompress --stdout',
+    'bz2' => 'bzip2 --decompress --stdout',
+    'xz' => 'xz --decompress --stdout',
+);
+
+has orig => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $index = Lintian::Index->new;
+        my $archive = $self->basename;
+        $index->identifier("$archive (orig)");
+        $index->basedir($self->basedir . $SLASH . 'orig');
+
+        return $index
+          if $self->native;
+
+        # source packages can be unpacked anywhere; no anchored roots
+        $index->anchored(0);
+
+        my %components = %{$self->components};
+
+        # keep sort order; root is missing below otherwise
+        my @tarballs = sort_by { $components{$_} } keys %components;
+
+        for my $tarball (@tarballs) {
+
+            my $component = $components{$tarball};
+
+            # so far, all archives with components had an extra level
+            my $component_dir = $index->basedir;
+            $component_dir .= $SLASH . $component
+              if length $component;
+
+            my $subindex = Lintian::Index->new;
+            $subindex->basedir($component_dir);
+
+            # source packages can be unpacked anywhere; no anchored roots
+            $index->anchored(0);
+
+            my ($extension) = ($tarball =~ /\.([^.]+)$/);
+            die encode_utf8("Source component $tarball has no file exension\n")
+              unless length $extension;
+
+            my $decompress = $DECOMPRESS_COMMAND{lc $extension};
+            die encode_utf8("Don't know how to decompress $tarball")
+              unless $decompress;
+
+            my @command
+              = (split($SPACE, $decompress),
+                $self->basedir . $SLASH . $tarball);
+
+            my $errors = $subindex->create_from_piped_tar(\@command);
+
+            push(@{$index->unpack_messages}, "$tarball . $_")
+              for grep { !/^tar: Ignoring / } uniq split(/\n/, $errors);
+
+            # treat hard links like regular files
+            my @hardlinks = grep { $_->is_hardlink } @{$subindex->sorted_list};
+            for my $item (@hardlinks) {
+
+                my $target = $subindex->lookup($item->link);
+
+                $item->unpacked_path($target->unpacked_path);
+                $item->size($target->size);
+                $item->link($EMPTY);
+
+                # turn into a regular file
+                my $perm = $item->perm;
+                $perm =~ s/^-/h/;
+                $item->perm($perm);
+
+                $item->path_info(
+                    ($item->path_info & ~Lintian::Index::Item::TYPE_HARDLINK)
+                    | Lintian::Index::Item::TYPE_FILE);
+            }
+
+            my @prefixes = @{$subindex->sorted_list};
+
+            # keep top level prefixes; no trailing slashes
+            s{^([^/]+).*$}{$1}s for @prefixes;
+
+            # squash identical values; ignore root entry ('')
+            my @unique = grep { length } uniq @prefixes;
+
+            # check for single common value
+            if (@unique == 1) {
+
+                # no trailing slash for directories
+                my $common = $unique[0];
+
+                # proceed if no file with that name (lacks slash)
+                my $conflict = $subindex->lookup($common);
+                unless (defined $conflict) {
+
+                    if ($common ne $component || length $component) {
+
+                        # shortens paths; keeps same base directory
+                        my $sub_errors = $subindex->drop_common_prefix;
+
+                        push(@{$index->unpack_errors}, "$tarball . $_")
+                          for uniq split(/\n/, $sub_errors);
+                    }
+                }
+            }
+
+            # lowers base directory to match index being merged into
+            $subindex->capture_common_prefix
+              if length $component;
+
+            $index->merge_in($subindex);
+        }
+
+        return $index;
+    }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Source/Overrides.pm b/lib/Lintian/Processable/Source/Overrides.pm
new file mode 100644
index 0000000..d4c446f
--- /dev/null
+++ b/lib/Lintian/Processable/Source/Overrides.pm
@@ -0,0 +1,109 @@
+# -*- perl -*- Lintian::Processable::Source::Overrides
+#
+# Copyright (C) 2019-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Source::Overrides;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use List::SomeUtils qw(first_value);
+
+use Moo::Role;
+use namespace::clean;
+
+with 'Lintian::Processable::Overrides';
+
+=head1 NAME
+
+Lintian::Processable::Source::Overrides - access to override data
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Source::Overrides provides an interface to overrides.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item override_file
+
+=cut
+
+has override_file => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        # prefer source/lintian-overrides to source.lintian-overrides
+        my @candidates = (
+            'debian/source/lintian-overrides',
+            'debian/source.lintian-overrides'
+        );
+
+        # pick the first
+        my $override_item= first_value { defined }
+        map { $self->patched->lookup($_) } @candidates;
+
+        return $override_item;
+    }
+);
+
+=item overrides
+
+=cut
+
+has overrides => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        return []
+          unless defined $self->override_file;
+
+        my $contents = $self->override_file->decoded_utf8;
+
+        return $self->parse_overrides($contents);
+    }
+);
+
+1;
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Source/Patched.pm b/lib/Lintian/Processable/Source/Patched.pm
new file mode 100644
index 0000000..229311f
--- /dev/null
+++ b/lib/Lintian/Processable/Source/Patched.pm
@@ -0,0 +1,161 @@
+# -*- perl -*- Lintian::Processable::Source::Patched
+#
+# Copyright (C) 2008 Russ Allbery
+# Copyright (C) 2009 Raphael Geissert
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Source::Patched;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Cwd;
+use List::SomeUtils qw(uniq);
+use IPC::Run3;
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8 decode_utf8);
+
+use Lintian::Index;
+use Lintian::Index::Item;
+
+const my $COLON => q{:};
+const my $SLASH => q{/};
+const my $NEWLINE => qq{\n};
+
+const my $NO_UMASK => 0000;
+const my $WAIT_STATUS_SHIFT => 8;
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::Source::Patched - access to sources with Debian patches applied
+
+=head1 SYNOPSIS
+
+    use Lintian::Processable;
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Source::Patched provides an interface to collected data about patched sources.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item patched
+
+Returns a index object representing a patched source tree.
+
+=cut
+
+has patched => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $index = Lintian::Index->new;
+        my $archive = $self->basename;
+        $index->identifier("$archive (patched)");
+        $index->basedir($self->basedir . $SLASH . 'unpacked');
+
+        # source packages can be unpacked anywhere; no anchored roots
+        $index->anchored(0);
+
+        path($index->basedir)->remove_tree
+          if -d $index->basedir;
+
+        print encode_utf8("N: Using dpkg-source to unpack\n")
+          if $ENV{'LINTIAN_DEBUG'};
+
+        my $saved_umask = umask;
+        umask $NO_UMASK;
+
+        my @unpack_command= (
+            qw(dpkg-source -q --no-check --extract),
+            $self->path, $index->basedir
+        );
+
+        # ignore STDOUT; older versions are not completely quiet with -q
+        my $unpack_errors;
+
+        run3(\@unpack_command, \undef, \undef, \$unpack_errors);
+        my $status = ($? >> $WAIT_STATUS_SHIFT);
+
+        $unpack_errors = decode_utf8($unpack_errors)
+          if length $unpack_errors;
+
+        if ($status) {
+            my $message = "Non-zero status $status from @unpack_command";
+            $message .= $COLON . $NEWLINE . $unpack_errors
+              if length $unpack_errors;
+
+            die encode_utf8($message);
+        }
+
+        umask $saved_umask;
+
+        my $index_errors = $index->create_from_basedir;
+
+        my $savedir = getcwd;
+        chdir($index->basedir)
+          or die encode_utf8('Cannot change to directory ' . $index->basedir);
+
+        # fix permissions
+        my @permissions_command
+          = ('chmod', '-R', 'u+rwX,o+rX,o-w', $index->basedir);
+        my $permissions_errors;
+
+        run3(\@permissions_command, \undef, \undef, \$permissions_errors);
+
+        $permissions_errors = decode_utf8($permissions_errors)
+          if length $permissions_errors;
+
+        chdir($savedir)
+          or die encode_utf8("Cannot change to directory $savedir");
+
+        my @messages = grep { !/^tar: Ignoring / }
+          split(/\n/, $unpack_errors . $index_errors . $permissions_errors);
+        push(@{$index->unpack_messages}, @messages);
+
+        return $index;
+    }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Source/Relation.pm b/lib/Lintian/Processable/Source/Relation.pm
new file mode 100644
index 0000000..e66297c
--- /dev/null
+++ b/lib/Lintian/Processable/Source/Relation.pm
@@ -0,0 +1,267 @@
+# -*- perl -*-
+# Lintian::Processable::Source::Relation -- interface to source package data collection
+
+# Copyright (C) 2008 Russ Allbery
+# Copyright (C) 2009 Raphael Geissert
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Source::Relation;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Relation;
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::Source::Relation - Lintian interface to source package data collection
+
+=head1 SYNOPSIS
+
+    my ($name, $type, $dir) = ('foobar', 'source', '/path/to/lab-entry');
+    my $collect = Lintian::Processable::Source::Relation->new($name);
+    if ($collect->native) {
+        print encode_utf8("Package is native\n");
+    }
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Source::Relation provides an interface to package data for source
+packages.  It implements data collection methods specific to source
+packages.
+
+This module is in its infancy.  Most of Lintian still reads all data from
+files in the laboratory whenever that data is needed and generates that
+data via collect scripts.  The goal is to eventually access all data about
+source packages via this module so that the module can cache data where
+appropriate and possibly retire collect scripts in favor of caching that
+data in memory.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item binary_relation (PACKAGE, FIELD)
+
+Returns a L<Lintian::Relation> object for the specified FIELD in the
+binary package PACKAGE in the F<debian/control> file.  FIELD should be
+one of the possible relationship fields of a Debian package or one of
+the following special values:
+
+=over 4
+
+=item All
+
+The concatenation of Pre-Depends, Depends, Recommends, and Suggests.
+
+=item Strong
+
+The concatenation of Pre-Depends and Depends.
+
+=item Weak
+
+The concatenation of Recommends and Suggests.
+
+=back
+
+If FIELD isn't present in the package, the returned Lintian::Relation
+object will be empty (present but satisfies nothing).
+
+Any substvars in F<debian/control> will be represented in the returned
+relation as packages named after the substvar.
+
+=item saved_binary_relations
+
+=cut
+
+has saved_binary_relations => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+my %alias = (
+    all    => [qw(Pre-Depends Depends Recommends Suggests)],
+    strong => [qw(Pre-Depends Depends)],
+    weak   => [qw(Recommends Suggests)]
+);
+
+my %known = map { $_ => 1 }
+  qw(pre-depends depends recommends suggests enhances breaks
+  conflicts provides replaces);
+
+sub binary_relation {
+    my ($self, $package, $name) = @_;
+
+    return undef
+      unless length $name;
+
+    my $lowercase = lc $name;
+
+    return undef
+      unless length $package;
+
+    my $relation = $self->saved_binary_relations->{$package}{$lowercase};
+    unless (defined $relation) {
+
+        if (length $alias{$lowercase}) {
+            $relation
+              = Lintian::Relation->new->logical_and(
+                map { $self->binary_relation($package, $_) }
+                  @{ $alias{$lowercase} });
+
+        } else {
+            croak encode_utf8("unknown relation field $name")
+              unless $known{$lowercase};
+
+            my $value
+              = $self->debian_control->installable_fields($package)
+              ->value($name);
+            $relation = Lintian::Relation->new->load($value);
+        }
+
+        $self->saved_binary_relations->{$package}{$lowercase} = $relation;
+    }
+
+    return $relation;
+}
+
+=item relation (FIELD)
+
+Returns a L<Lintian::Relation> object for the given build relationship
+field FIELD.  In addition to the normal build relationship fields, the
+following special field names are supported:
+
+=over 4
+
+=item Build-Depends-All
+
+The concatenation of Build-Depends, Build-Depends-Arch and
+Build-Depends-Indep.
+
+=item Build-Conflicts-All
+
+The concatenation of Build-Conflicts, Build-Conflicts-Arch and
+Build-Conflicts-Indep.
+
+=back
+
+If FIELD isn't present in the package, the returned Lintian::Relation
+object will be empty (present but satisfies nothing).
+
+=item saved_relation
+
+=cut
+
+has saved_relations => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+sub relation {
+    my ($self, $name) = @_;
+
+    return undef
+      unless length $name;
+
+    my $lowercase = lc $name;
+
+    my $relation = $self->saved_relations->{$lowercase};
+    unless (defined $relation) {
+
+        if ($name =~ /^Build-(Depends|Conflicts)-All$/i) {
+            my $type = $1;
+            my @fields
+              = ("Build-$type", "Build-$type-Indep", "Build-$type-Arch");
+            $relation
+              = Lintian::Relation->new->logical_and(map { $self->relation($_) }
+                  @fields);
+
+        } elsif ($name =~ /^Build-(Depends|Conflicts)(?:-(?:Arch|Indep))?$/i){
+            my $value = $self->fields->value($name);
+            $relation = Lintian::Relation->new->load($value);
+
+        } else {
+            croak encode_utf8("unknown relation field $name");
+        }
+
+        $self->saved_relations->{$lowercase} = $relation;
+    }
+
+    return $relation;
+}
+
+=item relation_norestriction (FIELD)
+
+The same as L</relation (FIELD)>, but ignores architecture
+restrictions and build profile restrictions in the FIELD field.
+
+=item saved_relations_norestriction
+
+=cut
+
+has saved_relations_norestriction => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+sub relation_norestriction {
+    my ($self, $name) = @_;
+
+    return undef
+      unless length $name;
+
+    my $lowercase = lc $name;
+
+    my $relation = $self->saved_relations_norestriction->{$lowercase};
+    unless (defined $relation) {
+
+        $relation = $self->relation($name)->restriction_less;
+        $self->saved_relations_norestriction->{$lowercase} = $relation;
+    }
+
+    return $relation;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Russ Allbery <rra@debian.org> for Lintian.
+Amended by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Processable/Source/Repacked.pm b/lib/Lintian/Processable/Source/Repacked.pm
new file mode 100644
index 0000000..4cf057b
--- /dev/null
+++ b/lib/Lintian/Processable/Source/Repacked.pm
@@ -0,0 +1,99 @@
+# -*- perl -*-
+# Lintian::Processable::Source::Repacked -- interface to source package data collection
+
+# Copyright (C) 2008 Russ Allbery
+# Copyright (C) 2009 Raphael Geissert
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Processable::Source::Repacked;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Lintian::Util qw($PKGREPACK_REGEX);
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Processable::Source::Repacked - Lintian interface to source package data collection
+
+=head1 SYNOPSIS
+
+    my ($name, $type, $dir) = ('foobar', 'source', '/path/to/lab-entry');
+    my $collect = Lintian::Processable::Source::Repacked->new($name);
+    if ($collect->native) {
+        print encode_utf8("Package is native\n");
+    }
+
+=head1 DESCRIPTION
+
+Lintian::Processable::Source::Repacked provides an interface to package data for source
+packages.  It implements data collection methods specific to source
+packages.
+
+This module is in its infancy.  Most of Lintian still reads all data from
+files in the laboratory whenever that data is needed and generates that
+data via collect scripts.  The goal is to eventually access all data about
+source packages via this module so that the module can cache data where
+appropriate and possibly retire collect scripts in favor of caching that
+data in memory.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item repacked
+
+Returns true if the source package has been "repacked" and false otherwise.
+This is determined from the version name containing "dfsg" or similar.
+
+=cut
+
+has repacked => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $upstream = $self->changelog_version->upstream;
+
+        return $upstream =~ $PKGREPACK_REGEX;
+    }
+);
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Russ Allbery <rra@debian.org> for Lintian.
+Amended by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Profile.pm b/lib/Lintian/Profile.pm
new file mode 100644
index 0000000..643e21f
--- /dev/null
+++ b/lib/Lintian/Profile.pm
@@ -0,0 +1,941 @@
+# Copyright (C) 2011 Niels Thykier <niels@thykier.net>
+# Copyright (C) 2018 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Profile;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(carp croak);
+use Const::Fast;
+use Cwd qw(realpath);
+use File::BaseDir qw(config_home config_files data_home);
+use File::Find::Rule;
+use List::Compare;
+use List::SomeUtils qw(any none uniq first_value);
+use Path::Tiny;
+use POSIX qw(ENOENT);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Dpkg::Vendor qw(get_current_vendor get_vendor_info);
+
+use Lintian::Data;
+use Lintian::Deb822;
+use Lintian::Tag;
+use Lintian::Util qw(match_glob);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $HYPHEN => q{-};
+const my $EQUAL => q{=};
+
+const my $FIELD_SEPARATOR => qr/ \s+ | \s* , \s* /sx;
+
+const my @VALID_HEADER_FIELDS => qw(
+  Profile
+  Extends
+  Enable-Tags-From-Check
+  Disable-Tags-From-Check
+  Enable-Tags
+  Disable-Tags
+);
+
+const my @VALID_BODY_FIELDS => qw(
+  Tags
+  Overridable
+);
+
+use Moo;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Profile - Profile parser for Lintian
+
+=head1 SYNOPSIS
+
+ my $profile = Lintian::Profile->new ('debian');
+
+=head1 DESCRIPTION
+
+Lintian::Profile handles finding, parsing and implementation of
+Lintian Profiles as well as loading the relevant Lintian checks.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item $prof->known_aliases()
+
+Returns a hash with old names that have new names.
+
+=item $prof->profile_list
+
+Returns a list ref of the (normalized) names of the profile and its
+parents.  The first element of the list is the name of the profile
+itself, the second is its parent and so on.
+
+Note: This list is a reference. The contents should not be modified.
+
+=item our_vendor
+
+=item $prof->name
+
+Returns the name of the profile, which may differ from the name used
+to create this instance of the profile (e.g. due to symlinks).
+
+=cut
+
+has known_aliases => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+has check_module_by_name => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+has check_path_by_name => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+has tag_names_for_check => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+has display_level_lookup => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub {
+        {
+            classification => 0,
+            pedantic       => 0,
+            info           => 0,
+            warning        => 1,
+            error          => 1,
+        }
+    }
+);
+
+has enabled_checks_by_name => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+has enabled_tags_by_name => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+has files => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+has known_tags_by_name => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+has name => (
+    is => 'rw',
+    coerce => sub { my ($string) = @_; return $string // $EMPTY;},
+    default => $EMPTY
+);
+
+has durable_tags_by_name => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+has data => (
+    is => 'rw',
+    lazy => 1,
+    default => sub {
+        my ($self) = @_;
+
+        my $data = Lintian::Data->new;
+
+        my @DATA_PATHS = $self->search_space('data');
+        $data->data_paths(\@DATA_PATHS);
+        $data->vendor($self->our_vendor);
+
+        return $data;
+    }
+);
+
+has parent_map => (
+    is => 'rw',
+    coerce => sub { my ($hashref) = @_; return ($hashref // {}); },
+    default => sub { {} }
+);
+
+has profile_list => (
+    is => 'rw',
+    coerce => sub { my ($arrayref) = @_; return ($arrayref // []); },
+    default => sub { [] }
+);
+
+has our_vendor => (is => 'rw');
+
+has include_dirs => (
+    is => 'rw',
+    coerce => sub { my ($arrayref) = @_; return ($arrayref // []); },
+    default => sub { [] }
+);
+
+# Temporary until aptdaemon (etc.) has been upgraded to handle
+# Lintian loading code from user dirs.
+# LP: #1162947
+has safe_include_dirs => (
+    is => 'rw',
+    coerce => sub { my ($arrayref) = @_; return ($arrayref // []); },
+    default => sub { [] }
+);
+
+has known_vendors => (
+    is => 'rw',
+    lazy => 1,
+    coerce => sub { my ($arrayref) = @_; return ($arrayref // []); },
+    default => sub {
+
+        my $vendor = Dpkg::Vendor::get_current_vendor();
+        croak encode_utf8('Could not determine the current vendor')
+          unless $vendor;
+
+        my @vendors;
+        push(@vendors, lc $vendor);
+
+        while ($vendor) {
+            my $info = Dpkg::Vendor::get_vendor_info($vendor);
+            # Cannot happen atm, but in case Dpkg::Vendor changes its internals
+            #  or our code changes
+            croak encode_utf8("Could not look up the parent vendor of $vendor")
+              unless $info;
+
+            $vendor = $info->{'Parent'};
+            push(@vendors, lc $vendor)
+              if $vendor;
+        }
+
+        return \@vendors;
+    }
+);
+
+has user_dirs => (
+    is => 'ro',
+    lazy => 1,
+    coerce => sub { my ($arrayref) = @_; return ($arrayref // []); },
+    default => sub {
+        my ($self) = @_;
+
+        my @user_data;
+
+        # XDG user data
+        push(@user_data, data_home('lintian'));
+
+        # legacy per-user data
+        push(@user_data, "$ENV{HOME}/.lintian")
+          if length $ENV{HOME};
+
+        # system wide user data
+        push(@user_data, '/etc/lintian');
+
+        const my @IMMUTABLE => grep { length && -e } @user_data;
+
+        return \@IMMUTABLE;
+    }
+);
+
+=item load ([$profname[, $ipath[, $extra]]])
+
+Loads a new profile.  $profname is the name of the profile and $ipath
+is a list reference containing the path to one (or more) Lintian
+"roots".
+
+If $profname is C<undef>, the default vendor will be loaded based on
+Dpkg::Vendor::get_current_vendor.
+
+If $ipath is not given, a default one will be used.
+
+=cut
+
+sub load {
+    my ($self, $profile_name, $requested_dirs, $allow_user_dirs) = @_;
+
+    $requested_dirs //= [];
+
+    my @distribution_dirs = ($ENV{LINTIAN_BASE} // '/usr/share/lintian');
+
+    const my @SAFE_INCLUDE_DIRS => (@{$requested_dirs}, @distribution_dirs);
+    $self->safe_include_dirs(\@SAFE_INCLUDE_DIRS);
+
+    my @all_dirs;
+
+    push(@all_dirs, @{$self->user_dirs})
+      if $allow_user_dirs && @{$self->user_dirs};
+
+    push(@all_dirs, @{$self->safe_include_dirs});
+
+    const my @ALL_INCLUDE_DIRS => @all_dirs;
+    $self->include_dirs(\@ALL_INCLUDE_DIRS);
+
+    for
+      my $tagdir (map { ($_ // q{.}) . '/tags' } @{$self->safe_include_dirs}) {
+
+        next
+          unless -d $tagdir;
+
+        my @tagpaths
+          = File::Find::Rule->file->name(qw(*.tag *.desc))->in($tagdir);
+        for my $tagpath (@tagpaths) {
+
+            my $tag = Lintian::Tag->new;
+            $tag->load($self, $tagpath);
+
+            die encode_utf8("Tag in $tagpath is not associated with a check")
+              unless length $tag->check;
+
+            next
+              if exists $self->known_tags_by_name->{$tag->name};
+
+            $self->known_tags_by_name->{$tag->name} = $tag;
+            $self->tag_names_for_check->{$tag->check} //= [];
+            push(@{$self->tag_names_for_check->{$tag->check}},$tag->name);
+
+            # record known aliases
+            my @taken
+              = grep { exists $self->known_aliases->{$_} }
+              @{$tag->renamed_from};
+
+            die encode_utf8('These aliases of the tag '
+                  . $tag->name
+                  . ' are taken already: '
+                  . join($SPACE, @taken))
+              if @taken;
+
+            for my $old_name (@{$tag->renamed_from}) {
+
+                if (exists $self->known_aliases->{$old_name}) {
+
+                    my $taken = $self->known_aliases->{$old_name};
+                    my $tag_name = $tag->name;
+                    warn encode_utf8(
+"Alias $old_name for $tag_name ignored; already taken by $taken"
+                    );
+
+                } else {
+                    $self->known_aliases->{$old_name} = $tag->name;
+                }
+            }
+        }
+    }
+
+    my @check_bases
+      = map {(($_ // q{.}).'/lib/Lintian/Check', ($_ // q{.}).'/checks')}
+      @{$self->safe_include_dirs};
+    for my $check_base (@check_bases) {
+
+        next
+          unless -d $check_base;
+
+        my @check_paths= File::Find::Rule->file->name('*.pm')->in($check_base);
+
+        for my $absolute (@check_paths) {
+
+            my $relative = path($absolute)->relative($check_base)->stringify;
+            $relative =~ s{\.pm$}{};
+
+            my $name = $relative;
+            $name =~ s{([[:upper:]])}{-\L$1}g;
+            $name =~ s{^-}{};
+            $name =~ s{/-}{/}g;
+
+            # ignore duplicates
+            next
+              if exists $self->check_module_by_name->{$name};
+
+            $self->check_path_by_name->{$name} = $absolute;
+
+            my $module = $relative;
+
+            # replace slashes with double colons
+            $module =~ s{/}{::}g;
+
+            $self->check_module_by_name->{$name} = "Lintian::Check::$module";
+        }
+    }
+
+    $self->read_profile($profile_name);
+
+    return;
+}
+
+=item $prof->known_tags
+
+=cut
+
+sub known_tags {
+    my ($self) = @_;
+
+    return keys %{ $self->known_tags_by_name };
+}
+
+=item $prof->enabled_tags
+
+=cut
+
+sub enabled_tags {
+    my ($self) = @_;
+
+    return keys %{ $self->enabled_tags_by_name };
+}
+
+=item $prof->get_tag ($name)
+
+Returns the Lintian::Tag for $tag if known.
+Otherwise it returns undef.
+
+=cut
+
+sub get_tag {
+    my ($self, $maybe_historical) = @_;
+
+    my $name = $self->get_current_name($maybe_historical);
+    return undef
+      unless length $name;
+
+    return $self->known_tags_by_name->{$name}
+      if exists $self->known_tags_by_name->{$name};
+
+    return undef;
+}
+
+=item get_current_name
+
+=cut
+
+sub get_current_name {
+    my ($self, $tag_name) = @_;
+
+    return $self->known_aliases->{$tag_name}
+      if exists $self->known_aliases->{$tag_name};
+
+    return $tag_name
+      if exists $self->known_tags_by_name->{$tag_name};
+
+    return $EMPTY;
+}
+
+=item set_durable ($tag)
+
+=cut
+
+sub set_durable {
+    my ($self, $maybe_historical, $status) = @_;
+
+    my $tag = $self->get_tag($maybe_historical);
+    croak encode_utf8("Unknown tag $maybe_historical.")
+      unless defined $tag;
+
+    $self->durable_tags_by_name->{$tag->name} = 1
+      if $status;
+
+    # settings from tag govern
+    delete $self->durable_tags_by_name->{$tag->name}
+      if !$status && !$tag->show_always;
+
+    return;
+}
+
+=item $prof->is_durable ($tag)
+
+Returns a false value if the tag has been marked as
+"non-overridable".  Otherwise it returns a truth value.
+
+=cut
+
+sub is_durable {
+    my ($self, $maybe_historical) = @_;
+
+    my $tag = $self->get_tag($maybe_historical);
+    croak encode_utf8("Unknown tag $maybe_historical.")
+      unless defined $tag;
+
+    return 1
+      if $tag->show_always
+      || exists $self->durable_tags_by_name->{$tag->name};
+
+    return 0;
+}
+
+=item $prof->known_checks
+
+=cut
+
+sub known_checks {
+    my ($self) = @_;
+
+    return keys %{ $self->check_module_by_name };
+}
+
+=item $prof->enabled_checks
+
+=cut
+
+sub enabled_checks {
+    my ($self) = @_;
+
+    return keys %{ $self->enabled_checks_by_name };
+}
+
+=item $prof->enable_tag ($name)
+
+Enables a tag.
+
+=cut
+
+sub enable_tag {
+    my ($self, $maybe_historical) = @_;
+
+    my $tag = $self->get_tag($maybe_historical);
+    croak encode_utf8("Unknown tag $maybe_historical.")
+      unless defined $tag;
+
+    $self->enabled_checks_by_name->{$tag->check}++
+      unless exists $self->enabled_tags_by_name->{$tag->name};
+
+    $self->enabled_tags_by_name->{$tag->name} = 1;
+
+    return;
+}
+
+=item $prof->disable_tag ($name)
+
+Disable a tag.
+
+=cut
+
+sub disable_tag {
+    my ($self, $maybe_historical) = @_;
+
+    my $tag = $self->get_tag($maybe_historical);
+    croak encode_utf8("Unknown tag $maybe_historical.")
+      unless defined $tag;
+
+    delete $self->enabled_checks_by_name->{$tag->check}
+      unless exists $self->enabled_tags_by_name->{$tag->name}
+      && --$self->enabled_checks_by_name->{$tag->check};
+
+    delete $self->enabled_tags_by_name->{$tag->name};
+
+    return;
+}
+
+=item read_profile
+
+=cut
+
+sub read_profile {
+    my ($self, $requested_name) = @_;
+
+    my @search_space;
+
+    if (!defined $requested_name) {
+        @search_space = map { "$_/main" } @{$self->known_vendors};
+
+    } elsif ($requested_name !~ m{/}) {
+        @search_space = ("$requested_name/main");
+
+    } elsif ($requested_name =~ m{^[^.]+/[^/.]+$}) {
+        @search_space = ($requested_name);
+
+    } else {
+        croak encode_utf8("$requested_name is not a valid profile name");
+    }
+
+    my @candidates;
+    for my $include_dir ( map { ($_ // q{.}) . '/profiles' }
+        @{$self->include_dirs} ) {
+        push(@candidates, map { "$include_dir/$_.profile" } @search_space);
+    }
+
+    my $path = first_value { -e } @candidates;
+
+    croak encode_utf8(
+        'Could not find a profile matching: ' . join($SPACE, @search_space))
+      unless length $path;
+
+    my $deb822 = Lintian::Deb822->new;
+    my @paragraphs = $deb822->read_file($path);
+
+    my ($header, @sections) = @paragraphs;
+
+    croak encode_utf8("Profile has no header in $path")
+      unless defined $header;
+
+    my $profile_name = $header->unfolded_value('Profile');
+    croak encode_utf8("Profile has no name in $path")
+      unless length $profile_name;
+
+    croak encode_utf8("Invalid Profile field in $path")
+      if $profile_name =~ m{^/} || $profile_name =~ m{\.};
+
+    # normalize name
+    $profile_name .= '/main'
+      unless $profile_name =~ m{/};
+
+    croak encode_utf8("Recursive definition of $profile_name")
+      if exists $self->parent_map->{$profile_name};
+
+    # Mark as being loaded.
+    $self->parent_map->{$profile_name} = 0;
+
+    $self->name($profile_name)
+      unless length $self->name;
+
+    $self->read_profile($header->unfolded_value('Extends'))
+      if $header->declares('Extends');
+
+    # prepend profile name after loading any parent
+    unshift(@{$self->profile_list}, $profile_name);
+
+    my @have_comma
+      = grep { $header->value($_) =~ / , /sx } @VALID_HEADER_FIELDS;
+    for my $section (@sections) {
+        push(@have_comma,
+            grep { $section->value($_) =~ / , /sx } @VALID_BODY_FIELDS);
+    }
+
+    warn
+"Please use spaces as separators in field $_ instead of commas in profile $path\n"
+      for uniq @have_comma;
+
+    my @unknown_header_fields = $header->extra(@VALID_HEADER_FIELDS);
+    croak encode_utf8("Unknown fields in header of profile $profile_name: "
+          . join($SPACE, @unknown_header_fields))
+      if @unknown_header_fields;
+
+    my @enable_check_patterns
+      = $header->trimmed_list('Enable-Tags-From-Check', $FIELD_SEPARATOR);
+    my @disable_check_patterns
+      = $header->trimmed_list('Disable-Tags-From-Check', $FIELD_SEPARATOR);
+
+    my @enable_checks;
+    for my $pattern (@enable_check_patterns) {
+        push(@enable_checks, match_glob($pattern, $self->known_checks));
+    }
+
+    my @disable_checks;
+    for my $pattern (@disable_check_patterns) {
+        push(@disable_checks, match_glob($pattern, $self->known_checks));
+    }
+
+    my @action_checks = uniq(@enable_checks, @disable_checks);
+
+    # make sure checks are loaded
+    my @needed_checks
+      = grep { !exists $self->check_module_by_name->{$_} } @action_checks;
+
+    croak encode_utf8("Profile $profile_name references unknown checks: "
+          . join($SPACE, @needed_checks))
+      if @needed_checks;
+
+    my @enable_tag_patterns
+      = $header->trimmed_list('Enable-Tags', $FIELD_SEPARATOR);
+    my @disable_tag_patterns
+      = $header->trimmed_list('Disable-Tags', $FIELD_SEPARATOR);
+
+    my @enable_tags;
+    for my $pattern (@enable_tag_patterns) {
+        push(@enable_tags, match_glob($pattern, $self->known_tags));
+    }
+
+    my @disable_tags;
+    for my $pattern (@disable_tag_patterns) {
+        push(@disable_tags, match_glob($pattern, $self->known_tags));
+    }
+
+    push(@enable_tags, @{$self->tag_names_for_check->{$_} // []})
+      for uniq @enable_checks;
+
+    push(@disable_tags, @{$self->tag_names_for_check->{$_} // []})
+      for uniq @disable_checks;
+
+    # disabling after enabling
+    $self->enable_tag($_) for uniq @enable_tags;
+    $self->disable_tag($_) for uniq @disable_tags;
+
+    my $section_number = 2;
+
+    for my $section (@sections){
+
+        my @unknown_fields = $section->extra(@VALID_BODY_FIELDS);
+        croak encode_utf8(
+"Unknown fields in section $section_number of profile $profile_name: "
+              . join($SPACE, @unknown_fields))
+          if @unknown_fields;
+
+        my @tags = $section->trimmed_list('Tags', $FIELD_SEPARATOR);
+        croak encode_utf8(
+"Tags field missing or empty in section $section_number of profile $profile_name"
+        )unless @tags;
+
+        my $overridable = $section->unfolded_value('Overridable') || 'yes';
+        if ($overridable !~ / ^ -? \d+ $ /msx) {
+            my $lowercase = lc $overridable;
+
+            if ($lowercase =~ / ^ y(?:es)? | true $ /msx) {
+                $overridable = 1;
+
+            } elsif ($lowercase =~ / ^ n[o]? | false $ /msx) {
+                $overridable = 0;
+
+            } else {
+                my $position = $section->position('Overridable');
+                croak encode_utf8(
+"$overridable is not a boolean value in profile $profile_name (line $position)"
+                );
+            }
+        }
+
+        for my $tag_name (@tags) {
+
+            if ($overridable) {
+                delete $self->durable_tags_by_name->{$tag_name};
+            } else {
+                $self->durable_tags_by_name->{$tag_name} = 1;
+            }
+        }
+
+    } continue {
+        $section_number++;
+    }
+
+    $self->our_vendor($self->profile_list->[0]);
+
+    # honor tag settings regardless of profile
+    my @show_always
+      = grep { $_->show_always } values %{$self->known_tags_by_name};
+
+    $self->durable_tags_by_name->{$_} = 1 for map { $_->name } @show_always;
+
+    return;
+}
+
+=item display_level_for_tag
+
+=cut
+
+sub display_level_for_tag {
+    my ($self, $tag_name) = @_;
+
+    my $tag = $self->get_tag($tag_name);
+    croak encode_utf8("Unknown tag $tag_name")
+      unless defined $tag;
+
+    return $self->display_level_lookup->{$tag->visibility};
+}
+
+=item tag_is_enabled(TAG)
+
+=cut
+
+sub tag_is_enabled {
+    my ($self, $maybe_historical) = @_;
+
+    my $tag = $self->get_tag($maybe_historical);
+    croak encode_utf8("Unknown tag $maybe_historical.")
+      unless defined $tag;
+
+    return 1
+      if exists $self->enabled_tags_by_name->{$tag->name};
+
+    return 0;
+}
+
+=item display(OPERATION, RELATION, VISIBILITY)
+
+Configure which tags are displayed by visibility.  OPERATION
+is C<+> to display the indicated tags, C<-> to not display the indicated
+tags, or C<=> to not display any tags except the indicated ones.  RELATION
+is one of C<< < >>, C<< <= >>, C<=>, C<< >= >>, or C<< > >>.  The
+OPERATION will be applied to all values of visibility that
+match the given RELATION on the VISIBILITY argument.  If
+either of those arguments are undefined, the action applies to any value
+for that variable.  For example:
+
+    $tags->display('=', '>=', 'error');
+
+turns off display of all tags and then enables display of any tag of
+visibility error or higher.
+
+    $tags->display('+', '>', 'warning');
+
+adds to the current configuration display of all tags with a visibility
+higher than warning.
+
+    $tags->display('-', '=', 'info');
+
+turns off display of tags of visibility info.
+
+This method throws an exception on errors, such as an unknown visibility or
+an impossible constraint (like C<< > serious >>).
+
+=cut
+
+# Generate a subset of a list given the element and the relation.  This
+# function makes a hard assumption that $rel will be one of <, <=, =, >=,
+# or >.  It is not syntax-checked.
+sub _relation_subset {
+    my ($self, $element, $rel, @list) = @_;
+
+    if ($rel eq $EQUAL) {
+        return grep { $_ eq $element } @list;
+    }
+
+    if (substr($rel, 0, 1) eq '<') {
+        @list = reverse @list;
+    }
+
+    my $found;
+    for my $i (0..$#list) {
+        if ($element eq $list[$i]) {
+            $found = $i;
+            last;
+        }
+    }
+
+    return ()
+      unless defined($found);
+
+    if (length($rel) > 1) {
+        return @list[$found .. $#list];
+
+    }
+
+    return ()
+      if $found == $#list;
+
+    return @list[($found + 1) .. $#list];
+}
+
+# Given the operation, relation, and visibility, produce a
+# human-readable representation of the display level string for errors.
+sub _format_level {
+    my ($self, $op, $rel, $visibility) = @_;
+
+    if (not defined $visibility) {
+        return "$op $rel";
+    } else {
+        return "$op $rel $visibility (visibility)";
+    }
+}
+
+sub display {
+    my ($self, $op, $rel, $visibility) = @_;
+
+    unless ($op =~ /^[+=-]\z/ and $rel =~ /^(?:[<>]=?|=)\z/) {
+        my $error = $self->_format_level($op, $rel, $visibility);
+        die encode_utf8('invalid display constraint ' . $error);
+    }
+
+    if ($op eq $EQUAL) {
+        for my $s (@Lintian::Tag::VISIBILITIES) {
+            $self->display_level_lookup->{$s} = 0;
+        }
+    }
+
+    my $status = ($op eq $HYPHEN ? 0 : 1);
+
+    my @visibilities;
+    if ($visibility) {
+        @visibilities
+          = $self->_relation_subset($visibility, $rel,
+            @Lintian::Tag::VISIBILITIES);
+    } else {
+        @visibilities = @Lintian::Tag::VISIBILITIES;
+    }
+
+    unless (@visibilities) {
+        my $error = $self->_format_level($op, $rel, $visibility);
+        die encode_utf8('invalid display constraint ' . $error);
+    }
+
+    for my $s (@visibilities) {
+        $self->display_level_lookup->{$s} = $status;
+    }
+
+    return;
+}
+
+=item search_space
+
+=cut
+
+sub search_space {
+    my ($self, $relative) = @_;
+
+    my @base_dirs;
+    for my $vendor (@{ $self->profile_list }) {
+
+        push(@base_dirs, map { "$_/vendors/$vendor" } @{$self->include_dirs});
+    }
+
+    push(@base_dirs, @{$self->include_dirs});
+
+    my @candidates = map { "$_/$relative" } @base_dirs;
+    my @search_space = grep { -e } @candidates;
+
+    return @search_space;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Niels Thykier <niels@thykier.net> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Relation.pm b/lib/Lintian/Relation.pm
new file mode 100644
index 0000000..b7b4b67
--- /dev/null
+++ b/lib/Lintian/Relation.pm
@@ -0,0 +1,788 @@
+# -*- perl -*-
+# Lintian::Relation -- operations on dependencies and relationships
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2004-2009 Russ Allbery <rra@debian.org>
+# Copyright (C) 2018 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Relation;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(confess);
+use Const::Fast;
+use List::SomeUtils qw(any);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Relation::Predicate;
+
+use Moo;
+use namespace::clean;
+
+use constant {
+    VISIT_PRED_NAME => 0,
+    VISIT_PRED_FULL => 1,
+    VISIT_OR_CLAUSE_FULL => 3,
+    VISIT_STOP_FIRST_MATCH => 4,
+};
+
+const my $EMPTY => q{};
+
+const my $BRANCH_TYPE => 0;
+const my $PREDICATE => 1;
+
+const my $FALSE => 0;
+
+=head1 NAME
+
+Lintian::Relation - Lintian operations on dependencies and relationships
+
+=head1 SYNOPSIS
+
+    my $depends = Lintian::Relation->new('foo | bar, baz');
+    print encode_utf8("yes\n") if $depends->satisfies('baz');
+    print encode_utf8("no\n") if $depends->satisfies('foo');
+
+=head1 DESCRIPTION
+
+This module provides functions for parsing and evaluating package
+relationship fields such as Depends and Recommends for binary packages and
+Build-Depends for source packages.  It parses a relationship into an
+internal format and can then answer questions such as "does this
+dependency require that a given package be installed" or "is this
+relationship a superset of another relationship."
+
+A dependency line is viewed as a predicate formula.  The comma separator
+means "and", and the alternatives separator means "or".  A bare package
+name is the predicate "a package of this name is available".  A package
+name with a version clause is the predicate "a package of this name that
+satisfies this version clause is available."  Architecture restrictions,
+as specified in Policy for build dependencies, are supported and also
+checked in the implication logic unless the new_norestriction()
+constructor is used.  With that constructor, architecture restrictions
+are ignored.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item trunk
+
+=cut
+
+has trunk => (is => 'rw', default => sub { ['AND'] });
+
+=item load (RELATION)
+
+Creates a new Lintian::Relation object corresponding to the parsed
+relationship RELATION.  This object can then be used to ask questions
+about that relationship.  RELATION may be C<undef> or the empty string, in
+which case the returned Lintian::Relation object is empty (always
+satisfied).
+
+=cut
+
+sub load {
+    my ($self, $condition, $with_restrictions) = @_;
+
+    $condition //= $EMPTY;
+
+    my @trunk = ('AND');
+
+    my @requirements = grep { length } split(/\s*,\s*/, $condition);
+    for my $requirement (@requirements) {
+
+        my @predicates;
+
+        my @alternatives = split(/\s*\|\s*/, $requirement);
+        for my $alternative (@alternatives) {
+
+            my $predicate = Lintian::Relation::Predicate->new;
+            $predicate->parse($alternative, $with_restrictions);
+
+            push(@predicates, ['PRED', $predicate]);
+        }
+
+        push(@trunk, @predicates)
+          if @predicates == 1;
+
+        push(@trunk, ['OR', @predicates])
+          if @predicates > 1;
+    }
+
+    $self->trunk(\@trunk);
+
+    return $self;
+}
+
+=item load_norestriction (RELATION)
+
+Creates a new Lintian::Relation object corresponding to the parsed
+relationship RELATION, ignoring architecture restrictions and restriction
+lists. This should be used in cases where we only care if a dependency is
+present in some cases and we don't want to require that the architectures
+match (such as when checking for proper build dependencies, since if there
+are architecture constraints the maintainer is doing something beyond
+Lintian's ability to analyze) or that the restrictions list match (Lintian
+can't handle dependency implications with build profiles yet).  RELATION
+may be C<undef> or the empty string, in which case the returned
+Lintian::Relation object is empty (always satisfied).
+
+=cut
+
+sub load_norestriction {
+    my ($self, $condition) = @_;
+
+    return $self->load($condition, $FALSE);
+}
+
+=item logical_and(RELATION, ...)
+
+Creates a new Lintian::Relation object produced by AND'ing all the
+relations together.  Semantically it is the similar to:
+
+ Lintian::Relation->new (join (', ', @relations))
+
+Except it can avoid some overhead and it works if some of the elements
+are Lintian::Relation objects already.
+
+=cut
+
+sub logical_and {
+    my ($self, @conditions) = @_;
+
+    my @tree = ('AND');
+
+    # make sure to add $self
+    for my $condition (@conditions, $self) {
+
+        my $relation;
+
+        if (ref $condition eq $EMPTY) {
+            # allow string conditions
+            $relation = Lintian::Relation->new->load($condition);
+
+        } else {
+            $relation = $condition;
+        }
+
+        next
+          if $relation->is_empty;
+
+        if (   $tree[$BRANCH_TYPE] eq 'AND'
+            && $relation->trunk->[$BRANCH_TYPE] eq 'AND') {
+
+            my @anded = @{$relation->trunk};
+            shift @anded;
+            push(@tree, @anded);
+
+        } else {
+            push(@tree, $relation->trunk);
+        }
+    }
+
+    my $created = Lintian::Relation->new;
+    $created->trunk(\@tree);
+
+    return $created;
+}
+
+=item redundancies()
+
+Returns a list of duplicated elements within the relation object.  Each
+element of the returned list will be a reference to an anonymous array
+holding a set of relations considered redundancies of each other.  Two
+relations are considered redundancies if one satisfies the other, meaning that
+if one relationship is satisfied, the other is necessarily satisfied.
+This relationship does not have to be commutative: the opposite
+implication may not hold.
+
+=cut
+
+sub redundancies {
+    my ($self) = @_;
+
+    # there are no redundancies unless the top-level relationship is AND.
+    return ()
+      unless $self->trunk->[$BRANCH_TYPE] eq 'AND';
+
+# The logic here is a bit complex in order to merge sets of duplicate
+# dependencies.  We want foo (<< 2), foo (>> 1), foo (= 1.5) to end up as
+# one set of redundancies, even though the first doesn't satisfy the second.
+#
+# $redundant_sets holds a hash, where the key is the earliest dependency in a set
+# and the value is a hash whose keys are the other dependencies in the
+# set.  $seen holds a map from package names to the duplicate sets that
+# they're part of, if they're not the earliest package in a set.  If
+# either of the dependencies in a duplicate pair were already seen, add
+# the missing one of the pair to the existing set rather than creating a
+# new one.
+    my %redundant_sets;
+
+    my @remaining = @{$self->trunk};
+
+    # discard AND identifier
+    shift @remaining;
+    my $i = 1;
+
+    my %seen;
+    while (@remaining > 1) {
+
+        my $branch_i = shift @remaining;
+        my $j = $i + 1;
+
+        # run against all others
+        for my $branch_j (@remaining) {
+
+            my $forward = implies_array($branch_i, $branch_j);
+            my $reverse = implies_array($branch_j, $branch_i);
+
+            if ($forward or $reverse) {
+                my $one = $self->to_string($branch_i);
+                my $two = $self->to_string($branch_j);
+
+                if ($seen{$one}) {
+                    $redundant_sets{$seen{$one}}{$two} = $j;
+                    $seen{$two} = $seen{$one};
+
+                } elsif ($seen{$two}) {
+                    $redundant_sets{$seen{$two}}{$one} = $i;
+                    $seen{$one} = $seen{$two};
+
+                } else {
+                    $redundant_sets{$one} ||= {};
+                    $redundant_sets{$one}{$two} = $j;
+                    $seen{$two} = $one;
+                }
+            }
+        } continue {
+            $j++;
+        }
+    } continue {
+        $i++;
+    }
+
+    return map { [$_, keys %{ $redundant_sets{$_}}] } keys %redundant_sets;
+}
+
+=item restriction_less
+
+Returns a restriction-less variant of this relation.
+
+=cut
+
+sub restriction_less {
+    my ($self) = @_;
+
+    my $unrestricted
+      = Lintian::Relation->new->load_norestriction($self->to_string);
+
+    return $unrestricted;
+}
+
+=item satisfies(RELATION)
+
+Returns true if the relationship satisfies RELATION, meaning that if the
+Lintian::Relation object is satisfied, RELATION will always be satisfied.
+RELATION may be either a string or another Lintian::Relation object.
+
+By default, architecture restrictions are honored in RELATION if it is a
+string.  If architecture restrictions should be ignored in RELATION,
+create a Lintian::Relation object with new_norestriction() and pass that
+in as RELATION instead of the string.
+
+=item implies_array
+
+=cut
+
+# This internal function does the heavy of AND, OR, and NOT logic.  It expects
+# two references to arrays instead of an object and a relation.
+sub implies_array {
+    my ($p, $q) = @_;
+
+    my $i;
+    my $q0 = $q->[$BRANCH_TYPE];
+    my $p0 = $p->[$BRANCH_TYPE];
+
+    if ($q0 eq 'PRED') {
+        if ($p0 eq 'PRED') {
+            return $p->[$PREDICATE]->satisfies($q->[$PREDICATE]);
+        } elsif ($p0 eq 'AND') {
+            $i = 1;
+            while ($i < @{$p}) {
+                return 1 if implies_array($p->[$i++], $q);
+            }
+            return 0;
+        } elsif ($p0 eq 'OR') {
+            $i = 1;
+            while ($i < @{$p}) {
+                return 0 if not implies_array($p->[$i++], $q);
+            }
+            return 1;
+        } elsif ($p0 eq 'NOT') {
+            return implies_array_inverse($p->[1], $q);
+        }
+    } elsif ($q0 eq 'AND') {
+        # Each of q's clauses must be deduced from p.
+        $i = 1;
+        while ($i < @{$q}) {
+            return 0 if not implies_array($p, $q->[$i++]);
+        }
+        return 1;
+
+    } elsif ($q0 eq 'OR') {
+        # If p is something other than OR, p needs to satisfy one of the
+        # clauses of q.  If p is an AND clause, q is satisfied if any of the
+        # clauses of p satisfy it.
+        #
+        # The interesting case is OR.  In this case, do an OR to OR comparison
+        # to determine if q's clause is a superset of p's clause as follows:
+        # take each branch of p and see if it satisfies a branch of q.  If
+        # each branch of p satisfies some branch of q, return 1.  Otherwise,
+        # return 0.
+        #
+        # Simple logic that requires that p satisfy at least one of the
+        # clauses of q considered in isolation will miss that a|b satisfies
+        # a|b|c, since a|b doesn't satisfy any of a, b, or c in isolation.
+        if ($p0 eq 'PRED') {
+            $i = 1;
+            while ($i < @{$q}) {
+                return 1 if implies_array($p, $q->[$i++]);
+            }
+            return 0;
+        } elsif ($p0 eq 'AND') {
+            $i = 1;
+            while ($i < @{$p}) {
+                return 1 if implies_array($p->[$i++], $q);
+            }
+            return 0;
+        } elsif ($p0 eq 'OR') {
+
+            my @p_branches = @{$p};
+            shift @p_branches;
+
+            my @q_branches = @{$q};
+            shift @q_branches;
+
+            for my $p_branch (@p_branches) {
+
+                return 0
+                  unless any { implies_array($p_branch, $_) }@q_branches;
+            }
+
+            return 1;
+
+        } elsif ($p->[$BRANCH_TYPE] eq 'NOT') {
+            return implies_array_inverse($p->[1], $q);
+        }
+
+    } elsif ($q0 eq 'NOT') {
+        if ($p0 eq 'NOT') {
+            return implies_array($q->[1], $p->[1]);
+        }
+        return implies_array_inverse($p, $q->[1]);
+    }
+
+    return undef;
+}
+
+# The public interface.
+sub satisfies {
+    my ($self, $condition) = @_;
+
+    my $relation;
+    if (ref $condition eq $EMPTY) {
+        # allow string conditions
+        $relation = Lintian::Relation->new->load($condition);
+
+    } else {
+        $relation = $condition;
+    }
+
+    return implies_array($self->trunk, $relation->trunk) // 0;
+}
+
+=item satisfies_inverse(RELATION)
+
+Returns true if the relationship satisfies that RELATION is certainly false,
+meaning that if the Lintian::Relation object is satisfied, RELATION cannot
+be satisfied.  RELATION may be either a string or another
+Lintian::Relation object.
+
+As with satisfies(), by default, architecture restrictions are honored in
+RELATION if it is a string.  If architecture restrictions should be
+ignored in RELATION, create a Lintian::Relation object with
+new_norestriction() and pass that in as RELATION instead of the string.
+
+=item implies_array_inverse
+
+=cut
+
+# This internal function does the heavily lifting for AND, OR, and NOT
+# handling for inverse implications.  It takes two references to arrays and
+# returns true iff the falsehood of the second can be deduced from the truth
+# of the first.
+sub implies_array_inverse {
+    my ($p, $q) = @_;
+    my $i;
+    my $q0 = $q->[$BRANCH_TYPE];
+    my $p0 = $p->[$BRANCH_TYPE];
+    if ($q0 eq 'PRED') {
+        if ($p0 eq 'PRED') {
+            return $p->[$PREDICATE]->satisfies_inverse($q->[$PREDICATE]);
+        } elsif ($p0 eq 'AND') {
+            # q's falsehood can be deduced from any of p's clauses
+            $i = 1;
+            while ($i < @{$p}) {
+                return 1 if implies_array_inverse($p->[$i++], $q);
+            }
+            return 0;
+        } elsif ($p0 eq 'OR') {
+            # q's falsehood must be deduced from each of p's clauses
+            $i = 1;
+            while ($i < @{$p}) {
+                return 0 if not implies_array_inverse($p->[$i++], $q);
+            }
+            return 1;
+        } elsif ($p0 eq 'NOT') {
+            return implies_array($q, $p->[1]);
+        }
+    } elsif ($q0 eq 'AND') {
+        # Any of q's clauses must be falsified by p.
+        $i = 1;
+        while ($i < @{$q}) {
+            return 1 if implies_array_inverse($p, $q->[$i++]);
+        }
+        return 0;
+    } elsif ($q0 eq 'OR') {
+        # Each of q's clauses must be falsified by p.
+        $i = 1;
+        while ($i < @{$q}) {
+            return 0 if not implies_array_inverse($p, $q->[$i++]);
+        }
+        return 1;
+    } elsif ($q0 eq 'NOT') {
+        return implies_array($p, $q->[1]);
+    }
+
+    return 0;
+}
+
+# The public interface.
+sub satisfies_inverse {
+    my ($self, $condition) = @_;
+
+    my $relation;
+    if (ref $condition eq $EMPTY) {
+        # allow string conditions
+        $relation = Lintian::Relation->new->load($condition);
+
+    } else {
+        $relation = $condition;
+    }
+
+    return implies_array_inverse($self->trunk, $relation->trunk) // 0;
+}
+
+=item to_string
+
+Returns the textual form of a relationship.  This converts the internal
+form back into the textual representation and returns that, not the
+original argument, so the spacing is standardized.  Returns undef on
+internal failures (such as an object in an unexpected format).
+
+=cut
+
+# The second argument isn't part of the public API.  It's a partial relation
+# that's not a blessed object and is used by to_string() internally so that it
+# can recurse.
+sub to_string {
+    my ($self, $branch) = @_;
+
+    my $tree = $branch // $self->trunk;
+
+    my $text;
+    if ($tree->[$BRANCH_TYPE] eq 'PRED') {
+
+        $text = $tree->[$PREDICATE]->to_string;
+
+    } elsif ($tree->[$BRANCH_TYPE] eq 'AND' || $tree->[$BRANCH_TYPE] eq 'OR') {
+
+        my $connector = ($tree->[$BRANCH_TYPE] eq 'AND') ? ', ' : ' | ';
+        my @separated = map { $self->to_string($_) } @{$tree}[1 .. $#{$tree}];
+        $text = join($connector, @separated);
+
+    } elsif ($tree->[$BRANCH_TYPE] eq 'NOT') {
+
+        # currently not generated by any relation
+        $text = '! ' . $tree->[$PREDICATE]->to_string;
+
+    } else {
+        confess encode_utf8("Case $tree->[$BRANCH_TYPE] not implemented");
+    }
+
+    return $text;
+}
+
+=item matches (REGEX[, WHAT])
+
+Check if one of the predicates in this relation matches REGEX.  WHAT
+determines what is tested against REGEX and if not given, defaults to
+VISIT_PRED_NAME.
+
+This method will return a truth value if REGEX matches at least one
+predicate or clause (as defined by the WHAT parameter - see below).
+
+NOTE: Often L</satisfies> (or L</satisfies_inverse>) is a better choice
+than this method.  This method should generally only be used when
+checking for a "pattern" package (e.g. phpapi-[\d\w+]+).
+
+
+WHAT can be one of:
+
+=over 4
+
+=item VISIT_PRED_NAME
+
+Match REGEX against the package name in each predicate (i.e. version
+and architecture constrains are ignored).  Each predicate is tested in
+isolation.  As an example:
+
+ my $rel = Lintian::Relation->new ('somepkg | pkg-0 (>= 1)');
+ # Will match (version is ignored)
+ $rel->matches (qr/^pkg-\d$/, VISIT_PRED_NAME);
+
+=item VISIT_PRED_FULL
+
+Match REGEX against the full (normalized) predicate (i.e. including
+version and architecture).  Each predicate is tested in isolation.
+As an example:
+
+ my $vrel = Lintian::Relation->new ('somepkg | pkg-0 (>= 1)');
+ my $uvrel = Lintian::Relation->new ('somepkg | pkg-0');
+
+ # Will NOT match (does not match with version)
+ $vrel->matches (qr/^pkg-\d$/, VISIT_PRED_FULL);
+ # Will match (this relation does not have a version)
+ $uvrel->matches (qr/^pkg-\d$/, VISIT_PRED_FULL);
+
+ # Will match (but only because there is a version)
+ $vrel->matches (qr/^pkg-\d \(.*\)$/, VISIT_PRED_FULL);
+ # Will NOT match (there is no version in the relation)
+ $uvrel->matches (qr/^pkg-\d  \(.*\)$/, VISIT_PRED_FULL);
+
+=item VISIT_OR_CLAUSE_FULL
+
+Match REGEX against the full (normalized) OR clause.  Each predicate
+will have both version and architecture constrains present.  As an
+example:
+
+
+ my $vpred = Lintian::Relation->new ('pkg-0 (>= 1)');
+ my $orrel = Lintian::Relation->new ('somepkg | pkg-0 (>= 1)');
+ my $rorrel = Lintian::Relation->new ('pkg-0 (>= 1) | somepkg');
+
+ # Will match
+ $vrel->matches (qr/^pkg-\d(?: \([^\)]\))?$/, VISIT_OR_CLAUSE_FULL);
+ # These Will NOT match (does not match the "|" and the "somepkg" part)
+ $orrel->matches (qr/^pkg-\d(?: \([^\)]\))?$/, VISIT_OR_CLAUSE_FULL);
+ $rorrel->matches (qr/^pkg-\d(?: \([^\)]\))?$/, VISIT_OR_CLAUSE_FULL);
+
+=back
+
+=cut
+
+sub matches {
+    my ($self, $regex, $what) = @_;
+    $what //= VISIT_PRED_NAME;
+    return $self->visit(sub { m/$regex/ }, $what | VISIT_STOP_FIRST_MATCH);
+}
+
+=item equals
+
+Same for full-string matches. Satisfies the perlcritic policy
+RegularExpressions::ProhibitFixedStringMatches.
+
+=cut
+
+sub equals {
+    my ($self, $string, $what) = @_;
+    $what //= VISIT_PRED_NAME;
+    return $self->visit(sub { $_ eq $string }, $what | VISIT_STOP_FIRST_MATCH);
+}
+
+=item visit (CODE[, FLAGS])
+
+Visit clauses or predicates of this relation.  Each clause or
+predicate is passed to CODE as first argument and will be available as
+C<$_>.
+
+The optional bitmask parameter, FLAGS, can be used to control what is
+visited and such.  If FLAGS is not given, it defaults to
+VISIT_PRED_NAME.  The possible values of FLAGS are:
+
+=over 4
+
+=item VISIT_PRED_NAME
+
+The package name in each predicate is visited, but the version and
+architecture part(s) are left out (if any).
+
+=item VISIT_PRED_FULL
+
+The full predicates are visited in turn.  The predicate will be
+normalized (by L</to_string>).
+
+=item VISIT_OR_CLAUSE_FULL
+
+CODE will be passed the full OR clauses of this relation.  The clauses
+will be normalized (by L</to_string>)
+
+Note: It will not visit the underlying predicates in the clause.
+
+=item VISIT_STOP_FIRST_MATCH
+
+Stop the visits the first time CODE returns a truth value.  This is
+similar to L<first|List::Util/first>, except visit will return the
+value returned by CODE.
+
+=back
+
+Except where a given flag specifies otherwise, the return value of
+visit is last value returned by CODE (or C<undef> for the empty
+relation).
+
+=cut
+
+# The last argument is not part of the public API.  It's a partial
+# relation that's not a blessed object and is used by visit()
+# internally so that it can recurse.
+
+sub visit {
+    my ($self, $code, $flags, $branch) = @_;
+
+    my $tree = $branch // $self->trunk;
+    my $rel_type = $tree->[$BRANCH_TYPE];
+
+    $flags //= 0;
+
+    if ($rel_type eq 'PRED') {
+        my $predicate = $tree->[$PREDICATE];
+        my $against = $predicate->name;
+        $against = $predicate->to_string
+          if $flags & VISIT_PRED_FULL;
+
+        local $_ = $against;
+        return scalar $code->($against);
+
+    } elsif (($flags & VISIT_OR_CLAUSE_FULL) == VISIT_OR_CLAUSE_FULL
+        and $rel_type eq 'OR') {
+
+        my $against = $self->to_string($tree);
+
+        local $_ = $against;
+        return scalar $code->($against);
+
+    } elsif ($rel_type eq 'AND'
+        or $rel_type eq 'OR'
+        or $rel_type eq 'NOT') {
+
+        for my $rel (@{$tree}[1 .. $#{$tree}]) {
+            my $ret = scalar $self->visit($code, $flags, $rel);
+            if ($ret && ($flags & VISIT_STOP_FIRST_MATCH)) {
+                return $ret;
+            }
+        }
+        return 0;
+    }
+
+    return 0;
+}
+
+=item is_empty
+
+Returns a truth value if this relation is empty (i.e. it contains no
+predicates).
+
+=cut
+
+sub is_empty {
+    my ($self) = @_;
+
+    return 1
+      if $self->trunk->[$BRANCH_TYPE] eq 'AND' && !$self->trunk->[1];
+
+    return 0;
+}
+
+=item unparsable_predicates
+
+Returns a list of predicates that were unparsable.
+
+They are returned in the original textual representation and are also
+sorted by said representation.
+
+=cut
+
+sub unparsable_predicates {
+    my ($self) = @_;
+
+    my @worklist = ($self->trunk);
+    my @unparsable;
+
+    while (my $current = pop(@worklist)) {
+
+        my $rel_type = $current->[$BRANCH_TYPE];
+
+        if ($rel_type ne 'PRED') {
+
+            push(@worklist, @{$current}[1 .. $#{$current}]);
+            next;
+        }
+
+        my $predicate = $current->[$PREDICATE];
+
+        push(@unparsable, $predicate->literal)
+          unless $predicate->parsable;
+    }
+
+    my @sorted = sort @unparsable;
+
+    return @sorted;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Russ Allbery <rra@debian.org> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Relation/Predicate.pm b/lib/Lintian/Relation/Predicate.pm
new file mode 100644
index 0000000..4714197
--- /dev/null
+++ b/lib/Lintian/Relation/Predicate.pm
@@ -0,0 +1,553 @@
+# -*- perl -*-
+# Lintian::Relation::Predicate -- relationship predicates
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2004-2009 Russ Allbery <rra@debian.org>
+# Copyright (C) 2018 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020-2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Relation::Predicate;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+
+use Lintian::Relation::Version qw(:all);
+
+use Moo;
+use namespace::clean;
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $COLON => q{:};
+
+const my $EQUAL => q{=};
+const my $LESS_THAN => q{<};
+const my $LESS_THAN_OR_EQUAL => q{<=};
+const my $DOUBLE_LESS_THAN => q{<<};
+const my $GREATER_THAN => q{>};
+const my $GREATER_THAN_OR_EQUAL => q{>=};
+const my $DOUBLE_GREATER_THAN => q{>>};
+
+const my $LEFT_PARENS => q{(};
+const my $RIGHT_PARENS => q{)};
+const my $LEFT_SQUARE => q{[};
+const my $RIGHT_SQUARE => q{]};
+const my $LEFT_ANGLE => q{<};
+const my $RIGHT_ANGLE => q{>};
+
+const my $TRUE => 1;
+const my $FALSE => 0;
+
+=head1 NAME
+
+Lintian::Relation::Predicate - Lintian type for relationship predicates
+
+=head1 SYNOPSIS
+
+    use Lintian::Relation::Predicate;
+
+=head1 DESCRIPTION
+
+This module provides functions for parsing and evaluating package
+relationships such as Depends and Recommends for binary packages and
+Build-Depends for source packages.  It parses a relationship into an
+internal format and can then answer questions such as "does this
+dependency require that a given package be installed" or "is this
+relationship a superset of another relationship."
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item literal
+
+=item C<parsable>
+
+=item name
+
+=item multiarch_qualifier
+
+=item version_operator
+
+=item reference_version
+
+=item build_architecture
+
+=item build_profile
+
+=cut
+
+has literal => (
+    is => 'rw',
+    default => $EMPTY,
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); }
+);
+
+has parsable => (is => 'rw', default => $FALSE);
+
+has name => (
+    is => 'rw',
+    default => $EMPTY,
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); }
+);
+
+has multiarch_qualifier => (
+    is => 'rw',
+    default => $EMPTY,
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); }
+);
+
+has version_operator => (
+    is => 'rw',
+    default => $EMPTY,
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); }
+);
+
+has reference_version => (
+    is => 'rw',
+    default => $EMPTY,
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); }
+);
+
+has build_architecture => (
+    is => 'rw',
+    default => $EMPTY,
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); }
+);
+
+has build_profile => (
+    is => 'rw',
+    default => $EMPTY,
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); }
+);
+
+=item parse
+
+=cut
+
+# The internal parser which converts a single package element of a
+# relationship into the parsed form used for later processing.  We permit
+# substvars to be used as package names so that we can use these routines with
+# the unparsed debian/control file.
+sub parse {
+    my ($self, $text, $with_restrictions) = @_;
+
+    $with_restrictions //= $TRUE;
+
+    # store the element as-is, so we can reconstitute it later
+    $self->literal($text);
+
+    if (
+        $text =~ m{
+        ^\s*                            # skip leading whitespace
+        (                               # package name or substvar (1)
+         (?:                            #  start of the name
+          [a-zA-Z0-9][a-zA-Z0-9+.-]*    #   start of a package name
+          |                             #   or
+          \$\{[a-zA-Z0-9:-]+\}          #   substvar
+         )                              #  end of start of the name
+         (?:                            #  substvars may be mixed in
+          [a-zA-Z0-9+.-]+               #   package name portion
+          |                             #   or
+          \$\{[a-zA-Z0-9:-]+\}          #   substvar
+         )*                             #  zero or more portions or substvars
+        )                               # end of package name or substvar
+        (?:[:]([a-z0-9-]+))?            # optional Multi-arch arch specification (2)
+        (?:                             # start of optional version
+         \s* \(                         # open parenthesis for version part
+         \s* (<<|<=|>=|>>|[=<>])        # relation part (3)
+         \s* ([^\)]+)                   # version (4)
+         \s* \)                         # closing parenthesis
+        )?                              # end of optional version
+        (?:                             # start of optional architecture
+         \s* \[                         # open bracket for architecture
+         \s* ([^\]]+)                   # architectures (5)
+         \s* \]                         # closing bracket
+        )?                              # end of optional architecture
+        (?:                             # start of optional restriction
+          \s* <                         # open bracket for restriction
+          \s* ([^,]+)                   # don't parse restrictions now
+          \s* >                         # closing bracket
+        )?                              # end of optional restriction
+    \s* $}x
+    ) {
+        $self->parsable($TRUE);
+
+        $self->name($1);
+        $self->multiarch_qualifier($2);
+        $self->version_operator($3);
+        $self->reference_version($4);
+        $self->build_architecture($5);
+        $self->build_profile($6);
+
+        $self->reference_version($EMPTY)
+          unless length $self->version_operator;
+
+        $self->version_operator($DOUBLE_LESS_THAN)
+          if $self->version_operator eq $LESS_THAN;
+
+        $self->version_operator($DOUBLE_GREATER_THAN)
+          if $self->version_operator eq $GREATER_THAN;
+
+        unless ($with_restrictions) {
+            $self->multiarch_qualifier('any');
+            $self->version_operator($EMPTY);
+            $self->reference_version($EMPTY);
+            $self->build_architecture($EMPTY);
+            $self->build_profile($EMPTY);
+        }
+    }
+
+    return;
+}
+
+=item satisfies
+
+=cut
+
+# This internal function does the heavily lifting of comparing two
+# elements.
+#
+# Takes two elements and returns true iff the second can be deduced from the
+# first.  If the second is falsified by the first (in other words, if self
+# actually satisfies not other), return 0.  Otherwise, return undef.  The 0 return
+# is used by implies_element_inverse.
+sub satisfies {
+    my ($self, $other) = @_;
+
+    if (!$self->parsable || !$other->parsable) {
+
+        return 1
+          if $self->to_string eq $other->to_string;
+
+        return undef;
+    }
+
+    # If the names don't match, there is no relationship between them.
+    return undef
+      if $self->name ne $other->name;
+
+    # the restriction formula forms a disjunctive normal form expression one
+    # way to check whether A <dnf1> satisfies A <dnf2> is to check:
+    #
+    # if dnf1 == dnf1 OR dnf2:
+    #     the second dependency is superfluous because the first dependency
+    #     applies in all cases the second one applies
+    #
+    # an easy way to check for equivalence of the two dnf expressions would be
+    # to construct the truth table for both expressions ("dnf1" and "dnf1 OR
+    # dnf2") for all involved profiles and then comparing whether they are
+    # equal
+    #
+    # the size of the truth tables grows with 2 to the power of the amount of
+    # involved profile names but since there currently only exist six possible
+    # profile names (see data/fields/build-profiles) that should be okay
+    #
+    # FIXME: we are not doing this check yet so if we encounter a dependency
+    # with build profiles we assume that one does not satisfy the other:
+
+    return undef
+      if length $self->build_profile
+      || length $other->build_profile;
+
+    # If the names match, then the only difference is in the architecture or
+    # version clauses.  First, check architecture.  The architectures for self
+    # must be a superset of the architectures for other.
+    my @self_arches = split($SPACE, $self->build_architecture);
+    my @other_arches = split($SPACE, $other->build_architecture);
+    if (@self_arches || @other_arches) {
+        my $self_arch_neg = @self_arches && $self_arches[0] =~ /^!/;
+        my $other_arch_neg = @other_arches && $other_arches[0] =~ /^!/;
+
+  # If self has no arches, it is a superset of other and we should fall through
+  # to the version check.
+        if (not @self_arches) {
+            # nothing
+        }
+
+     # If other has no arches, it is a superset of self and there are no useful
+     # implications.
+        elsif (not @other_arches) {
+
+            return undef;
+        }
+
+        # Both have arches.  If neither are negated, we know nothing useful
+        # unless other is a subset of self.
+        elsif (not $self_arch_neg and not $other_arch_neg) {
+            my %self_arches = map { $_ => 1 } @self_arches;
+            my $subset = 1;
+            for my $arch (@other_arches) {
+                $subset = 0 unless $self_arches{$arch};
+            }
+
+            return undef
+              unless $subset;
+        }
+
+       # If both are negated, we know nothing useful unless self is a subset of
+       # other (and therefore has fewer things excluded, and therefore is more
+       # general).
+        elsif ($self_arch_neg and $other_arch_neg) {
+            my %other_arches = map { $_ => 1 } @other_arches;
+            my $subset = 1;
+            for my $arch (@self_arches) {
+                $subset = 0 unless $other_arches{$arch};
+            }
+
+            return undef
+              unless $subset;
+        }
+
+       # If other is negated and self isn't, we'd need to know the full list of
+       # arches to know if there's any relationship, so bail.
+        elsif (not $self_arch_neg and $other_arch_neg) {
+
+            return undef;
+        }
+
+# If self is negated and other isn't, other is a subset of self iff none of the
+# negated arches in self are present in other.
+        elsif ($self_arch_neg and not $other_arch_neg) {
+            my %other_arches = map { $_ => 1 } @other_arches;
+            my $subset = 1;
+            for my $arch (@self_arches) {
+                $subset = 0 if $other_arches{substr($arch, 1)};
+            }
+
+            return undef
+              unless $subset;
+        }
+    }
+
+    # Multi-arch architecture specification
+
+    # According to the spec, only the special value "any" is allowed
+    # and it is "recommended" to consider "other such package
+    # relations as unsatisfiable".  That said, there seem to be an
+    # interest in supporting ":<arch>" as well, so we will (probably)
+    # have to accept those as well.
+    #
+    # Other than that, we would need to know that the package has the
+    # field "Multi-arch: allowed", but we cannot check that here.  So
+    # we assume that it is okay.
+
+    # pkg has no chance of satisfing pkg:Y unless Y is 'any'
+    return undef
+      if !length $self->multiarch_qualifier
+      && length $other->multiarch_qualifier
+      && $other->multiarch_qualifier ne 'any';
+
+    # TODO: Review this case.  Are there cases where other cannot
+    # disprove self due to the ":any"-qualifier?  For now, we
+    # assume there are no such cases.
+    # pkg:X has no chance of satisfying pkg
+    return undef
+      if length $self->multiarch_qualifier
+      && !length $other->multiarch_qualifier;
+
+    # For now assert that only the identity holds.  In practise, the
+    # "pkg:X" (for any valid value of X) seems to satisfy "pkg:any",
+    # fixing that is a TODO (because version clauses complicates
+    # matters)
+    # pkg:X has no chance of satisfying pkg:Y unless X equals Y
+    return undef
+      if length $self->multiarch_qualifier
+      && length $other->multiarch_qualifier
+      && $self->multiarch_qualifier ne $other->multiarch_qualifier;
+
+  # Now, down to version.  The implication is true if self's clause is stronger
+  # than other's, or is equivalent.
+
+    # If other has no version clause, then self's clause is always stronger.
+    return 1
+      unless length $other->version_operator;
+
+# If other does have a version clause, then self must also have one to have any
+# useful relationship.
+    return undef
+      unless length $self->version_operator;
+
+ # other wants an exact version, so self must provide that exact version.  self
+ # disproves other if other's version is outside the range enforced by self.
+    if ($other->version_operator eq $EQUAL) {
+        if ($self->version_operator eq $DOUBLE_LESS_THAN) {
+            return versions_lte($self->reference_version,
+                $other->reference_version) ? 0 : undef;
+        } elsif ($self->version_operator eq $LESS_THAN_OR_EQUAL) {
+            return versions_lt($self->reference_version,
+                $other->reference_version) ? 0 : undef;
+        } elsif ($self->version_operator eq $DOUBLE_GREATER_THAN) {
+            return versions_gte($self->reference_version,
+                $other->reference_version) ? 0 : undef;
+        } elsif ($self->version_operator eq $GREATER_THAN_OR_EQUAL) {
+            return versions_gt($self->reference_version,
+                $other->reference_version) ? 0 : undef;
+        } elsif ($self->version_operator eq $EQUAL) {
+            return versions_equal($self->reference_version,
+                $other->reference_version) ? 1 : 0;
+        }
+    }
+
+# A greater than clause may disprove a less than clause.  Otherwise, if
+# self's clause is <<, <=, or =, the version must be <= other's to satisfy other.
+    if ($other->version_operator eq $LESS_THAN_OR_EQUAL) {
+        if ($self->version_operator eq $DOUBLE_GREATER_THAN) {
+            return versions_gte($self->reference_version,
+                $other->reference_version) ? 0 : undef;
+        } elsif ($self->version_operator eq $GREATER_THAN_OR_EQUAL) {
+            return versions_gt($self->reference_version,
+                $other->reference_version) ? 0 : undef;
+        } elsif ($self->version_operator eq $EQUAL) {
+            return versions_lte($self->reference_version,
+                $other->reference_version) ? 1 : 0;
+        } else {
+            return versions_lte($self->reference_version,
+                $other->reference_version) ? 1 : undef;
+        }
+    }
+
+    # Similar, but << is stronger than <= so self's version must be << other's
+    # version if the self relation is <= or =.
+    if ($other->version_operator eq $DOUBLE_LESS_THAN) {
+        if (   $self->version_operator eq $DOUBLE_GREATER_THAN
+            || $self->version_operator eq $GREATER_THAN_OR_EQUAL) {
+            return versions_gte($self->reference_version,
+                $self->reference_version) ? 0 : undef;
+        } elsif ($self->version_operator eq $DOUBLE_LESS_THAN) {
+            return versions_lte($self->reference_version,
+                $other->reference_version) ? 1 : undef;
+        } elsif ($self->version_operator eq $EQUAL) {
+            return versions_lt($self->reference_version,
+                $other->reference_version) ? 1 : 0;
+        } else {
+            return versions_lt($self->reference_version,
+                $other->reference_version) ? 1 : undef;
+        }
+    }
+
+    # Same logic as above, only inverted.
+    if ($other->version_operator eq $GREATER_THAN_OR_EQUAL) {
+        if ($self->version_operator eq $DOUBLE_LESS_THAN) {
+            return versions_lte($self->reference_version,
+                $other->reference_version) ? 0 : undef;
+        } elsif ($self->version_operator eq $LESS_THAN_OR_EQUAL) {
+            return versions_lt($self->reference_version,
+                $other->reference_version) ? 0 : undef;
+        } elsif ($self->version_operator eq $EQUAL) {
+            return versions_gte($self->reference_version,
+                $other->reference_version) ? 1 : 0;
+        } else {
+            return versions_gte($self->reference_version,
+                $other->reference_version) ? 1 : undef;
+        }
+    }
+    if ($other->version_operator eq $DOUBLE_GREATER_THAN) {
+        if (   $self->version_operator eq $DOUBLE_LESS_THAN
+            || $self->version_operator eq $LESS_THAN_OR_EQUAL) {
+            return versions_lte($self->reference_version,
+                $other->reference_version) ? 0 : undef;
+        } elsif ($self->version_operator eq $DOUBLE_GREATER_THAN) {
+            return versions_gte($self->reference_version,
+                $other->reference_version) ? 1 : undef;
+        } elsif ($self->version_operator eq $EQUAL) {
+            return versions_gt($self->reference_version,
+                $other->reference_version) ? 1 : 0;
+        } else {
+            return versions_gt($self->reference_version,
+                $other->reference_version) ? 1 : undef;
+        }
+    }
+
+    return undef;
+}
+
+=item satisfies_inverse
+
+=cut
+
+# This internal function does the heavy lifting of inverse implication between
+# two elements.  Takes two elements and returns true iff the falsehood of
+# the second can be deduced from the truth of the first.  In other words, self
+# satisfies not other, or restated, other satisfies not self.  (Since if a satisfies b, not b
+# satisfies not a.)  Due to the return value of implies_element(), we can let it
+# do most of the work.
+sub satisfies_inverse {
+    my ($self, $other) = @_;
+
+    my $result = $self->satisfies($other);
+    return undef
+      if !defined $result;
+
+    return $result ? 0 : 1;
+}
+
+=item to_string
+
+=cut
+
+sub to_string {
+    my ($self) = @_;
+
+    # return the original value
+    return $self->literal
+      unless $self->parsable;
+
+    my $text = $self->name;
+
+    $text .= $COLON . $self->multiarch_qualifier
+      if length $self->multiarch_qualifier;
+
+    $text
+      .= $SPACE
+      . $LEFT_PARENS
+      . $self->version_operator
+      . $SPACE
+      . $self->reference_version
+      . $RIGHT_PARENS
+      if length $self->version_operator;
+
+    $text.= $SPACE . $LEFT_SQUARE . $self->build_architecture . $RIGHT_SQUARE
+      if length $self->build_architecture;
+
+    $text .= $SPACE . $LEFT_ANGLE . $self->build_profile . $RIGHT_ANGLE
+      if length $self->build_profile;
+
+    return $text;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Russ Allbery <rra@debian.org> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Relation/Version.pm b/lib/Lintian/Relation/Version.pm
new file mode 100644
index 0000000..d3552b7
--- /dev/null
+++ b/lib/Lintian/Relation/Version.pm
@@ -0,0 +1,213 @@
+# -*- perl -*-
+# Lintian::Relation::Version -- comparison operators on Debian versions
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2004-2009 Russ Allbery <rra@debian.org>
+# Copyright (C) 2009 Adam D. Barratt <adam@adam-barratt.org.uk>
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Relation::Version;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+BEGIN {
+    our @EXPORT_OK = qw(versions_equal versions_lte versions_gte versions_lt
+      versions_gt versions_compare versions_comparator);
+    our %EXPORT_TAGS = ('all' => \@EXPORT_OK);
+}
+
+use AptPkg::Config '$_config';
+use Carp qw(croak);
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+const my $EQUAL => q{=};
+
+my $versioning = do {
+    my $config = AptPkg::Config->new;
+    $config->init;
+    $config->system->versioning;
+};
+
+=head1 NAME
+
+Lintian::Relation::Version - Comparison operators on Debian versions
+
+=head1 SYNOPSIS
+
+    print encode_utf8("yes\n") if versions_equal('1.0', '1.00');
+    print encode_utf8("yes\n") if versions_gte('1.1', '1.0');
+    print encode_utf8("no\n") if versions_lte('1.1', '1.0');
+    print encode_utf8("yes\n") if versions_gt('1.1', '1.0');
+    print encode_utf8("no\n") if versions_lt('1.1', '1.1');
+    print encode_utf8("yes\n") if versions_compare('1.1', '<=', '1.1');
+
+=head1 DESCRIPTION
+
+This module provides five functions for comparing version numbers.  The
+underlying implementation uses C<libapt-pkg-perl> to ensure that
+the results match what dpkg will expect.
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item versions_equal(A, B)
+
+Returns true if A is equal to B (C<=>) and false otherwise.
+
+=cut
+
+sub versions_equal {
+    my ($p, $q) = @_;
+    my $result;
+
+    return 1 if $p eq $q;
+
+    $result = $versioning->compare($p, $q);
+
+    return ($result == 0);
+}
+
+=item versions_lte(A, B)
+
+Returns true if A is less than or equal (C<< <= >>) to B and false
+otherwise.
+
+=cut
+
+sub versions_lte {
+    my ($p, $q) = @_;
+    my $result;
+
+    return 1 if $p eq $q;
+
+    $result = $versioning->compare($p, $q);
+
+    return ($result <= 0);
+}
+
+=item versions_gte(A, B)
+
+Returns true if A is greater than or equal (C<< >= >>) to B and false
+otherwise.
+
+=cut
+
+sub versions_gte {
+    my ($p, $q) = @_;
+    my $result;
+
+    return 1 if $p eq $q;
+
+    $result = $versioning->compare($p, $q);
+
+    return ($result >= 0);
+}
+
+=item versions_lt(A, B)
+
+Returns true if A is less than (C<<< << >>>) B and false otherwise.
+
+=cut
+
+sub versions_lt {
+    my ($p, $q) = @_;
+    my $result;
+
+    return 0 if $p eq $q;
+
+    $result = $versioning->compare($p, $q);
+
+    return ($result < 0);
+}
+
+=item versions_gt(A, B)
+
+Returns true if A is greater than (C<<< >> >>>) B and false otherwise.
+
+=cut
+
+sub versions_gt {
+    my ($p, $q) = @_;
+    my $result;
+
+    return 0 if $p eq $q;
+
+    $result = $versioning->compare($p, $q);
+
+    return ($result > 0);
+}
+
+=item versions_compare(A, OP, B)
+
+Returns true if A OP B, where OP is one of C<=>, C<< <= >>, C<< >= >>,
+C<<< << >>>, or C<<< >> >>>, and false otherwise.
+
+=cut
+
+sub versions_compare {
+    my ($p, $op, $q) = @_;
+    if    ($op eq  $EQUAL) { return versions_equal($p, $q) }
+    elsif ($op eq '<=') { return versions_lte($p, $q) }
+    elsif ($op eq '>=') { return versions_gte($p, $q) }
+    elsif ($op eq '<<') { return versions_lt($p, $q) }
+    elsif ($op eq '>>') { return versions_gt($p, $q) }
+    else { croak encode_utf8("unknown operator $op") }
+}
+
+=item versions_comparator (A, B)
+
+Returns -1, 0 or 1 if the version A is (respectively) less than, equal
+to or greater than B.  This is useful for (e.g.) sorting a list of
+versions:
+
+ foreach my $version (sort versions_comparator @versions) {
+    ...
+ }
+
+=cut
+
+# Use a prototype to avoid confusing Perl when used with sort.
+
+sub versions_comparator {
+    my ($p, $q) = @_;
+    return $versioning->compare($p, $q);
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Russ Allbery <rra@debian.org> for Lintian and adapted
+to use libapt-pkg-perl by Adam D. Barratt <adam@adam-barratt-org.uk>.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Reporting/ResourceManager.pm b/lib/Lintian/Reporting/ResourceManager.pm
new file mode 100644
index 0000000..171b6b7
--- /dev/null
+++ b/lib/Lintian/Reporting/ResourceManager.pm
@@ -0,0 +1,233 @@
+# Copyright (C) 2014 Niels Thykier <niels@thykier.net>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+# A simple resource manager for html_reports
+package Lintian::Reporting::ResourceManager;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use File::Basename qw(basename);
+use File::Copy qw(copy);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Util qw(get_file_digest);
+
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $EQUALS => q{=};
+
+const my $BASE64_UNIT => 4;
+const my $WIDELY_READABLE_FOLDER => oct(755);
+
+=head1 NAME
+
+Lintian::Reporting::ResourceManager -- A simple resource manager for html_reports
+
+=head1 SYNOPSIS
+
+ use Lintian::Reporting::ResourceManager;
+ 
+ my $resMan = Lintian::Reporting::ResourceManager->new(
+    'html_dir' => 'path/to/HTML-root',
+ );
+ # Copy the resource
+ $resMan->install_resource('path/to/my-image.png', { install_method => 'copy'} );
+ # Move the resource
+ $resMan->install_resource('path/to/generated-styles.css');
+ print encode_utf8('Image: ' . $resMan->resource_url('my-image.png'), "\n");
+ print encode_utf8('CSS: ' . $resMan->resource_url('generated-styles.css'), "\n");
+
+=head1 DESCRIPTION
+
+A simple resource manager for Lintian's reporting tool,
+B<html_reports>.
+
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item new(TYPE, OPTS)
+
+Instantiates a new resource manager.
+
+OPTS is a key-value list, which must contain the key "html_dir" set to
+the root of the HTML path.  It is beneath this path that all resources
+will be installed
+
+=cut
+
+sub new {
+    my ($class, %opts) = @_;
+    my $self = {%opts,};
+    croak encode_utf8('Missing required parameter html_dir (or it is undef)')
+      if not defined $opts{'html_dir'};
+    $self->{'_resource_cache'} = {};
+    $self->{'_resource_integrity'} = {};
+    return bless($self, $class);
+}
+
+=back
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item install_resource(RESOURCE[, OPT])
+
+Installs RESOURCE into the html root.  The resource may be renamed
+(based on content etc.).
+
+Note that the basename of RESOURCE must be unique between all
+resources installed.  See L</resource_url(RESOURCE_NAME)>.
+
+If OPT is given, it must be a hashref with 0 or more of the following
+keys (and values).
+
+=over 4
+
+=item install_method
+
+Can be "copy" or "move" (default).  If set to "move", the original file
+will be renamed into its new location.  Otherwise, a copy is done and
+the original file is left in place.
+
+=item source_file
+
+By default, the path denoted by RESOURCE is both the resource name and
+the source file.  This option can be used to install a given file as
+RESOURCE regardless of the basename of the source file.
+
+If this is passed, RESOURCE must be a basename (i.e. without any
+slashes).
+
+=back
+
+=cut
+
+sub install_resource {
+    my ($self, $resource_name, $opt) = @_;
+    my $resource_root = $self->{'html_dir'} . '/resources';
+    my $method = 'move';
+    my ($basename, $install_name, $resource, $digest, $b64digest);
+    $method = $opt->{'install_method'}
+      if $opt && exists($opt->{'install_method'});
+    if ($opt && exists($opt->{'source_file'})) {
+        $basename = $resource_name;
+        $resource = $opt->{'source_file'};
+
+        if ($basename =~ m{ / }msx) {
+
+            croak encode_utf8(
+                join($SPACE,
+                    qq(Resource "${resource_name}" must not contain "/"),
+                    'when source_file is given')
+            );
+        }
+    } else {
+        $basename = basename($resource_name);
+        $resource = $resource_name;
+    }
+    $digest = get_file_digest('sha256', $resource);
+    $install_name = $digest->clone->hexdigest;
+    $b64digest = $digest->b64digest;
+
+    while (length($b64digest) % $BASE64_UNIT) {
+        $b64digest .= $EQUALS;
+    }
+
+    croak encode_utf8("Resource name ${basename} already in use")
+      if defined($self->{'_resource_cache'}{$basename});
+    if ($basename =~ m/^.+(\.[^\.]+)$/xsm) {
+        my $ext = $1;
+        $install_name .= $ext;
+    }
+
+    if (!-d $resource_root) {
+        mkdir($resource_root, $WIDELY_READABLE_FOLDER)
+          or die encode_utf8("Cannot mkdir $resource_root");
+    }
+
+    my $target_file = "$resource_root/$install_name";
+    if ($method eq 'move') {
+        rename($resource, $target_file)
+          or die encode_utf8("Cannot rename $resource to $target_file");
+
+    } elsif ($method eq 'copy') {
+        copy($resource, $target_file)
+          or croak encode_utf8("Cannot copy $resource to $target_file: $!");
+    } else {
+        croak encode_utf8(
+            join($SPACE,
+                "Unknown install method ${method}",
+                '- please use "move" or "copy"')
+        );
+    }
+    $self->{'_resource_cache'}{$basename} = $target_file;
+    $self->{'_resource_integrity'}{$basename} = "sha256-${b64digest}";
+    return;
+}
+
+=item resource_url(RESOURCE_NAME)
+
+Returns the path (relative to the HTML root) to a resource installed
+via L</install_resource(RESOURCE)>, where RESOURCE_NAME is the
+basename of the path given to install_resource.
+
+=cut
+
+sub resource_url {
+    my ($self, $resource_name) = @_;
+    croak encode_utf8("Unknown resource $resource_name")
+      if not defined($self->{'_resource_cache'}{$resource_name});
+    return $self->{'_resource_cache'}{$resource_name};
+}
+
+=item resource_integrity_value(RESOURCE_NAME)
+
+Return a string that is valid in the "integrity" field of a C<< <link>
+>> HTML tag.  (See https://www.w3.org/TR/SRI/)
+
+=cut
+
+sub resource_integrity_value {
+    my ($self, $resource_name) = @_;
+    croak encode_utf8("Unknown resource $resource_name")
+      if not defined($self->{'_resource_integrity'}{$resource_name});
+    return $self->{'_resource_integrity'}{$resource_name};
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Niels Thykier <niels@thykier.net> for Lintian.
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Reporting/Util.pm b/lib/Lintian/Reporting/Util.pm
new file mode 100644
index 0000000..ecf34cf
--- /dev/null
+++ b/lib/Lintian/Reporting/Util.pm
@@ -0,0 +1,217 @@
+# Hey emacs! This is a -*- Perl -*- script!
+# Lintian::Reporting::Util -- Perl utility functions for lintian's reporting framework
+
+# Copyright (C) 1998 Christian Schwarz
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Reporting::Util;
+
+=head1 NAME
+
+Lintian::Reporting::Util - Lintian utility functions
+
+=head1 SYNOPSIS
+
+ use Lintian::Reporting::Util qw(load_state_cache find_backlog);
+
+ my $cache = load_state_cache('path/to/state-dir');
+ my @backlog = find_backlog('2.12', $cache);
+
+=head1 DESCRIPTION
+
+This module contains a number of utility subs that are nice to have
+for the reporting framework, but on their own did not warrant their
+own module.
+
+Most subs are imported only on request.
+
+=head1 FUNCTIONS
+
+=over 4
+
+=cut
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Exporter qw(import);
+use File::Temp qw(tempfile);
+use List::Util qw(shuffle);
+use Path::Tiny;
+use Syntax::Keyword::Try;
+use Unicode::UTF8 qw(encode_utf8);
+use YAML::XS ();
+
+use Lintian::Relation::Version qw(versions_equal versions_comparator);
+
+our @EXPORT_OK = (
+    qw(
+      load_state_cache
+      save_state_cache
+      find_backlog
+    )
+);
+
+const my $WIDELY_READABLE => oct(644);
+
+=item load_state_cache(STATE_DIR)
+
+[Reporting tools only] Load the state cache from STATE_DIR.
+
+=cut
+
+sub load_state_cache {
+    my ($state_dir) = @_;
+    my $state_file = "$state_dir/state-cache";
+    my $state = {};
+
+    return $state
+      unless -e $state_file;
+
+    my $yaml = path($state_file)->slurp;
+
+    try {
+        $state = YAML::XS::Load($yaml);
+
+    } catch {
+        # Not sure what Load does in case of issues; perldoc YAML says
+        # very little about it.  Based on YAML::Error, I guess it will
+        # write stuff to STDERR and use die/croak, but it remains a
+        # guess.
+        die encode_utf8(
+            "$state_file was invalid; please fix or remove it.\n$@");
+    }
+
+    $state //= {};
+
+    if (ref($state) ne 'HASH') {
+        die encode_utf8("$state_file was invalid; please fix or remove it.");
+    }
+    return $state;
+}
+
+=item save_state_cache(STATE_DIR, STATE)
+
+[Reporting tools only] Save the STATE cache to STATE_DIR.
+
+=cut
+
+sub save_state_cache {
+    my ($state_dir, $state) = @_;
+    my $state_file = "$state_dir/state-cache";
+    my ($tmp_fd, $tmp_path);
+
+    ($tmp_fd, $tmp_path) = tempfile('state-cache-XXXXXX', DIR => $state_dir);
+    ## TODO: Should tmp_fd be binmode'd as we use YAML::XS?
+
+    # atomic replacement of the state file; not a substitute for
+    # proper locking, but it will at least ensure that the file
+    # is in a consistent state.
+    try {
+        print {$tmp_fd} encode_utf8(YAML::XS::Dump($state));
+
+        close($tmp_fd) or die encode_utf8("close $tmp_path: $!");
+
+        # There is no secret in this.  Set it to 0644, so it does not
+        # require sudo access on lintian.d.o to read the file.
+        chmod($WIDELY_READABLE, $tmp_path);
+
+        rename($tmp_path, $state_file)
+          or die encode_utf8("rename $tmp_path -> $state_file: $!");
+
+    } catch {
+        my $err = $@;
+        if (-e $tmp_path) {
+            # Ignore error as we have a more important one
+            unlink($tmp_path)
+              or warn encode_utf8("Cannot unlink $tmp_path");
+        }
+        die encode_utf8($err);
+
+        # perlcritic 1.140-1 requires the semicolon on the next line
+    };
+
+    return 1;
+}
+
+=item find_backlog(LINTIAN_VERSION, STATE)
+
+[Reporting tools only] Given the current lintian version and the
+harness state, return a list of group ids that are part of the
+backlog.  The list is sorted based on what version of Lintian
+processed the package.
+
+Note the result is by design not deterministic to reduce the
+risk of all large packages being in the same run (e.g. like
+gcc-5 + gcc-5-cross + gcc-6 + gcc-6-cross).
+
+=cut
+
+sub find_backlog {
+    my ($lintian_version, $state) = @_;
+    my (@backlog, %by_version, @low_priority);
+    for my $group_id (keys(%{$state->{'groups'}})) {
+        my $last_version = '0';
+        my $group_data = $state->{'groups'}{$group_id};
+        my $is_out_of_date;
+        # Does this group repeatedly fail with the current version
+        # of lintian?
+        if (    exists($group_data->{'processing-errors'})
+            and $group_data->{'processing-errors'} > 2
+            and exists($group_data->{'last-error-by'})
+            and $group_data->{'last-error-by'} ne $lintian_version) {
+            # To avoid possible "starvation", we will give lower priority
+            # to packages that repeatedly fail.  They will be retried as
+            # the backlog is cleared.
+            push(@low_priority, $group_id);
+            next;
+        }
+        if (exists($group_data->{'out-of-date'})) {
+            $is_out_of_date = $group_data->{'out-of-date'};
+        }
+        if (exists($group_data->{'last-processed-by'})) {
+            $last_version = $group_data->{'last-processed-by'};
+        }
+        $is_out_of_date = 1
+          if not versions_equal($last_version, $lintian_version);
+        push(@{$by_version{$last_version}}, $group_id) if $is_out_of_date;
+    }
+    for my $v (sort(versions_comparator keys(%by_version))) {
+        push(@backlog, shuffle(@{$by_version{$v}}));
+    }
+    push(@backlog, shuffle(@low_priority)) if @low_priority;
+    return @backlog;
+}
+
+=back
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Screen.pm b/lib/Lintian/Screen.pm
new file mode 100644
index 0000000..28d8c85
--- /dev/null
+++ b/lib/Lintian/Screen.pm
@@ -0,0 +1,80 @@
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Screen;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo::Role;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Screen -- Common facilities for Lintian screens
+
+=head1 SYNOPSIS
+
+ use Moo;
+ use namespace::clean;
+
+ with('Lintian::Screen');
+
+=head1 DESCRIPTION
+
+A class for masking Lintian tags after they are issued
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item name
+
+=item advocates
+
+=item reason
+
+=item see_also
+
+=cut
+
+has name => (is => 'rw', default => sub { {} });
+has advocates => (is => 'rw', default => sub { {} });
+has reason => (is => 'rw', default => sub { {} });
+has see_also => (is => 'rw', default => sub { {} });
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Screen/Autotools/LongLines.pm b/lib/Lintian/Screen/Autotools/LongLines.pm
new file mode 100644
index 0000000..1de9b85
--- /dev/null
+++ b/lib/Lintian/Screen/Autotools/LongLines.pm
@@ -0,0 +1,61 @@
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Screen::Autotools::LongLines;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Screen';
+
+sub suppress {
+    my ($self, $processable, $hint) = @_;
+
+    my $item = $hint->pointer->item;
+
+    # ./configure script in source root only
+    return 1
+      if $item->name eq 'configure'
+      && ( defined $processable->patched->resolve_path('configure.in')
+        || defined $processable->patched->resolve_path('configure.ac'));
+
+    # Automake's Makefile.in in any folder
+    return 1
+      if $item->basename eq 'Makefile.in'
+      && defined $processable->patched->resolve_path(
+        $item->dirname . '/Makefile.am');
+
+    # any m4 macro as long as ./configure is present
+    return 1
+      if $item->name =~ m{^ m4/ }x
+      && defined $processable->patched->resolve_path('configure');
+
+    return 0;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Screen/Coq/Cmxs/Prerequisites.pm b/lib/Lintian/Screen/Coq/Cmxs/Prerequisites.pm
new file mode 100644
index 0000000..aaf4600
--- /dev/null
+++ b/lib/Lintian/Screen/Coq/Cmxs/Prerequisites.pm
@@ -0,0 +1,49 @@
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Screen::Coq::Cmxs::Prerequisites;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Screen';
+
+sub suppress {
+    my ($self, $processable, $hint) = @_;
+
+    my $item = $hint->pointer->item;
+
+    return 1
+      if $item->name =~ m{ [.]cmxs $}x
+      && ( $processable->type eq 'binary'
+        || $processable->type eq 'udeb');
+
+    return 0;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Screen/Emacs/Elpa/Scripts.pm b/lib/Lintian/Screen/Emacs/Elpa/Scripts.pm
new file mode 100644
index 0000000..a943620
--- /dev/null
+++ b/lib/Lintian/Screen/Emacs/Elpa/Scripts.pm
@@ -0,0 +1,50 @@
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Screen::Emacs::Elpa::Scripts;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Screen';
+
+sub suppress {
+    my ($self, $processable, $hint) = @_;
+
+    my $item = $hint->pointer->item;
+
+    return 1
+      if $item->name =~ m{^usr/lib/emacsen-common/packages/}
+      && ( $processable->type eq 'binary'
+        || $processable->type eq 'udeb')
+      && $processable->relation('strong')->satisfies('emacsen-common');
+
+    return 0;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Screen/Examples/InTests.pm b/lib/Lintian/Screen/Examples/InTests.pm
new file mode 100644
index 0000000..c1bc63f
--- /dev/null
+++ b/lib/Lintian/Screen/Examples/InTests.pm
@@ -0,0 +1,47 @@
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Screen::Examples::InTests;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Screen';
+
+sub suppress {
+    my ($self, $processable, $hint) = @_;
+
+    my $item = $hint->pointer->item;
+
+    return 1
+      if $item->name =~ m{^ test s? / }x;
+
+    return 0;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Screen/Examples/Ship/Devhelp.pm b/lib/Lintian/Screen/Examples/Ship/Devhelp.pm
new file mode 100644
index 0000000..2727628
--- /dev/null
+++ b/lib/Lintian/Screen/Examples/Ship/Devhelp.pm
@@ -0,0 +1,47 @@
+# Copyright (C) 2022 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Screen::Examples::Ship::Devhelp;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Screen';
+
+sub suppress {
+    my ($self, $processable, $hint) = @_;
+
+    my $item = $hint->pointer->item;
+
+    return 1
+      if $item->name =~ m{^ usr/share/doc/ [^/]+ /examples/ }x;
+
+    return 0;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Screen/Glibc/Control/Ldconfig.pm b/lib/Lintian/Screen/Glibc/Control/Ldconfig.pm
new file mode 100644
index 0000000..403d940
--- /dev/null
+++ b/lib/Lintian/Screen/Glibc/Control/Ldconfig.pm
@@ -0,0 +1,45 @@
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Screen::Glibc::Control::Ldconfig;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Screen';
+
+sub suppress {
+    my ($self, $processable, $hint) = @_;
+
+    return 1
+      if $processable->source_name eq 'glibc';
+
+    return 0;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Screen/Python/Egg/Metadata.pm b/lib/Lintian/Screen/Python/Egg/Metadata.pm
new file mode 100644
index 0000000..facff08
--- /dev/null
+++ b/lib/Lintian/Screen/Python/Egg/Metadata.pm
@@ -0,0 +1,53 @@
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Screen::Python::Egg::Metadata;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Screen';
+
+sub suppress {
+    my ($self, $processable, $hint) = @_;
+
+    my $item = $hint->pointer->item;
+
+    return 1
+      if $item->dirname =~ m{ [^/] [.] dist-info / $}x
+      && defined $item->parent_dir->child('METADATA')
+      && defined $item->parent_dir->child('WHEEL');
+
+    return 1
+      if $item->dirname =~ m{ [^/] [.] egg-info / $}x
+      && defined $item->parent_dir->child('PKG-INFO');
+
+    return 0;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Screen/Toolchain/Gnat/AliReadOnly.pm b/lib/Lintian/Screen/Toolchain/Gnat/AliReadOnly.pm
new file mode 100644
index 0000000..682f549
--- /dev/null
+++ b/lib/Lintian/Screen/Toolchain/Gnat/AliReadOnly.pm
@@ -0,0 +1,52 @@
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Screen::Toolchain::Gnat::AliReadOnly;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Screen';
+
+sub suppress {
+    my ($self, $processable, $hint) = @_;
+
+    my $item = $hint->pointer->item;
+
+    return 1
+      if $item->name
+      =~ m{^ usr/lib/ [^/]+ /ada/adalib/ [^/]+ / [^/]+ [.] ali \b }x
+      && ( $processable->type eq 'binary'
+        || $processable->type eq 'udeb')
+      && $processable->name =~ /-dev$/
+      && $processable->relation('strong')->satisfies('gnat');
+
+    return 0;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Screen/Web/Cgi/Scripts.pm b/lib/Lintian/Screen/Web/Cgi/Scripts.pm
new file mode 100644
index 0000000..f667111
--- /dev/null
+++ b/lib/Lintian/Screen/Web/Cgi/Scripts.pm
@@ -0,0 +1,48 @@
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Screen::Web::Cgi::Scripts;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Moo;
+use namespace::clean;
+
+with 'Lintian::Screen';
+
+sub suppress {
+    my ($self, $processable, $hint) = @_;
+
+    my $item = $hint->pointer->item;
+
+    return 1
+      if ($item->is_script || $item->is_elf)
+      && $item->name =~ m{^ usr/lib/cgi-bin/ }x;
+
+    return 0;
+}
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/SlidingWindow.pm b/lib/Lintian/SlidingWindow.pm
new file mode 100644
index 0000000..2274d78
--- /dev/null
+++ b/lib/Lintian/SlidingWindow.pm
@@ -0,0 +1,171 @@
+# -*- perl -*-
+
+# Copyright (C) 2013 Bastien ROUCARIES
+# Copyright (C) 2021 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::SlidingWindow;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Moo;
+use namespace::clean;
+
+const my $DEFAULT_BLOCK_SIZE => 4096;
+const my $EMPTY => q{};
+
+has handle => (is => 'rw');
+has blocksize => (is => 'rw', default => $DEFAULT_BLOCK_SIZE);
+has blocknumber => (is => 'rw', default => -1);
+has blocksub => (is => 'rw', default => undef);
+has _queue => (is => 'rw', default =>  sub {[q{}, q{}]});
+
+sub readwindow {
+    my ($self) = @_;
+    my $window;
+
+    my $first = $self->blocknumber < 0;
+    {
+        # This path is too hot for autodie at its current performance
+        # (at the time of writing, that would be autodie/2.23).
+        # - Benchmark chromium-browser/32.0.1700.123-2/source
+        no autodie qw(read);
+        my $blocksize = $self->blocksize;
+        # Read twice the amount in the first window and split that
+        # into "two parts".  That way we avoid half a block followed
+        # by a full block with the first half being identical to the
+        # previous one.
+        $blocksize *= 2 if $first;
+        my $res = read($self->handle, $window, $blocksize);
+        if (not $res) {
+            die encode_utf8("read failed: $!\n") unless defined($res);
+            return;
+        }
+    }
+
+    if(defined($self->blocksub)) {
+        local $_ = $window;
+        $self->blocksub->();
+        $window = $_;
+    }
+
+    $self->blocknumber($self->blocknumber + 1);
+
+    if ($first && $self->blocksize < length($window)) {
+        # Split the first block into two windows.  We assume here that
+        # if the two halves are not of equal length, then it is
+        # because the file is shorter than 2*blocksize.  In this case,
+        # make the second half the shorter (it shouldn't matter and it
+        # is easier to do this way).
+        my $blocksize = $self->blocksize;
+        $self->_queue->[0] = substr($window, 0, $blocksize);
+        $self->_queue->[1] = substr($window, $blocksize);
+        return $window;
+    }
+    shift(@{$self->_queue});
+    push(@{$self->_queue}, $window);
+    return join($EMPTY, @{$self->_queue});
+}
+
+=head1 NAME
+
+Lintian::SlidingWindow - Lintian interface to sliding window match
+
+=head1 SYNOPSIS
+
+    use Lintian::SlidingWindow;
+
+    my $sfd = Lintian::SlidingWindow->new('<','someevilfile.c', sub { $_ = lc($_); });
+    my $window;
+    while ($window = $sfd->readwindow) {
+       if (index($window, 'evil') > -1) {
+           if($window =~
+                 m/software \s++ shall \s++
+                   be \s++ used \s++ for \s++ good \s*+ ,?+ \s*+
+                   not \s++ evil/xsim) {
+              # do something like : tag 'license-problem-json-evil';
+           }
+       }
+    }
+
+=head1 DESCRIPTION
+
+Lintian::SlidingWindow provides a way of matching some pattern,
+including multi line pattern, without needing to fully load the
+file in memory.
+
+=head1 CLASS METHODS
+
+=over 4
+
+=item new(HANDLE[, BLOCKSUB[, BLOCKSIZE]])
+
+Create a new sliding window by reading from a given HANDLE, which must
+be open for reading. Optionally run BLOCKSUB against each block. Note
+that BLOCKSUB should apply transform byte by byte and does not depend
+of context.
+
+Each window consists of up to two blocks of BLOCKSIZE characters.
+
+=back
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item readwindow
+
+Return a new block of sliding window. Return undef at end of file.
+
+=item C<blocksize>
+
+=item blocknumber
+
+=item handle
+
+=item blocksub
+
+=back
+
+=head1 DIAGNOSTICS
+
+=over 4
+
+=item no data type specified
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Bastien ROUCARIES for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Spelling.pm b/lib/Lintian/Spelling.pm
new file mode 100644
index 0000000..1a8d7fc
--- /dev/null
+++ b/lib/Lintian/Spelling.pm
@@ -0,0 +1,295 @@
+# -*- perl -*-
+# Lintian::Spelling -- Lintian spelling checks shared between multiple scripts
+
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2004 Marc Brockschmidt
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2023 Axel Beckert
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Spelling;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+our @EXPORT_OK = qw(
+  check_spelling
+  check_spelling_picky
+);
+
+use Carp qw(croak);
+use Const::Fast;
+use Unicode::UTF8 qw(encode_utf8);
+
+const my $SPACE => q{ };
+const my $DOUBLE_QUOTE => q{"};
+
+=head1 NAME
+
+Lintian::Spelling -- Lintian spell checks shared between multiple scripts
+
+=head1 SYNOPSIS
+
+    use Lintian::Spelling qw(check_spelling);
+
+=head1 DESCRIPTION
+
+This module provides functions to do some Lintian checks that need to be
+done in multiple places.  There are certain low-level checks, such as
+validating a maintainer name and e-mail address or checking spelling,
+which apply in multiple situations and should be done in multiple checks
+scripts or in checks scripts and the Lintian front-end.
+
+The functions provided by this module issue tags directly, usually either
+taking the tag name to issue as an argument or dynamically constructing
+the tag name based on function parameters.  The caller is responsible for
+ensuring that all tags are declared in the relevant *.desc file with
+proper descriptions and other metadata.  The possible tags issued by each
+function are described in the documentation for that function.
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item check_spelling(TEXT,[ EXCEPTIONS,] CODEREF)
+
+Performs a spelling check of TEXT.  Call CODEREF once for each unique
+misspelling with the following arguments:
+
+=over 4
+
+=item The misspelled word/phrase
+
+=item The correct word/phrase
+
+=back
+
+If EXCEPTIONS is given, it will be used as an array ref of exceptions.
+Any lowercase word appearing as a key of that array will never be
+considered a spelling mistake (exception being if it is a part of a
+multiword misspelling).
+
+Returns the number of spelling mistakes found in TEXT.
+
+=cut
+
+my (%CORRECTIONS, @CORRECTIONS_MULTIWORD);
+
+sub check_spelling {
+    my ($data, $text, $acceptable, $code_ref, $duplicate_check) = @_;
+
+    croak encode_utf8('No spelling data')
+      unless defined $data;
+
+    return 0
+      unless $text;
+
+    if (  !defined $code_ref
+        && defined $acceptable
+        && ref($acceptable) eq 'CODE') {
+        $code_ref = $acceptable;
+        $acceptable = [];
+    }
+
+    $acceptable //= [];
+    $duplicate_check //= 1;
+
+    my %exceptions = map { $_ => 1 } @{$acceptable};
+
+    my (%seen, %duplicates, $last_word, $quoted);
+    my $counter = 0;
+    my $text_orig = $text;
+
+    if (!%CORRECTIONS) {
+        my $corrections_multiword
+          = $data->load('spelling/corrections-multiword', '\|\|');
+        my $corrections = $data->load('spelling/corrections', '\|\|');
+        for my $misspelled ($corrections->all) {
+            $CORRECTIONS{$misspelled} = $corrections->value($misspelled);
+        }
+        for my $misspelled_regex ($corrections_multiword->all) {
+            my $correct = $corrections_multiword->value($misspelled_regex);
+            push(@CORRECTIONS_MULTIWORD,
+                [qr/\b($misspelled_regex)\b/, $correct]);
+        }
+    }
+
+    $text =~ tr/[]//d;
+    # Strip () except for "(s)" suffixes.
+    $text =~ s/(\((?!s\))|(?<!\(s)\))//gi;
+    $text =~ s/(\w-)\s*\n\s*/$1/;
+    $text =~ tr/\r\n \t/ /s;
+    $text =~ s/\s++/ /g;
+
+    # trim both ends
+    $text =~ s/^\s+|\s+$//g;
+
+    for my $word (split($SPACE, $text)) {
+        my $ends_with_punct = 0;
+        my $q = $word =~ tr/"/"/;
+        # Change quoting on "foo or foo" but not "foo".
+        if ($q & 1) {
+            $quoted = not $quoted;
+        }
+        $ends_with_punct = 1 if $word =~ s/[.,;:?!]+$//;
+
+        if ($duplicate_check and defined($last_word) and $last_word eq $word) {
+            # Avoid flagging words inside quoted text.
+            $code_ref->("$word $word (duplicate word)", $word)
+              if not $quoted
+              and not $duplicates{$word}++
+              and not $ends_with_punct
+              and $text_orig !~ /\b$word\s*\($word\b/
+              and $text_orig !~ /\b$word\)\s*$word\b/;
+        }
+
+        if ($word =~ m/^[A-Za-z]+$/ and not $ends_with_punct) {
+            $last_word = $word;
+        } else {
+            $last_word = undef;
+        }
+
+        next
+          if $word =~ /^[A-Z]{1,5}\z/;
+
+        # Some exceptions are based on case (e.g. "teH").
+        next
+          if exists $exceptions{$word};
+
+        my $lcword = lc $word;
+        if (exists $CORRECTIONS{$lcword}
+            && !exists $exceptions{$lcword}) {
+
+            $counter++;
+            my $correction = $CORRECTIONS{$lcword};
+
+            if ($word =~ /^[A-Z]+$/) {
+                $correction = uc $correction;
+            } elsif ($word =~ /^[A-Z]/) {
+                $correction = ucfirst $correction;
+            }
+
+            next
+              if $seen{$lcword}++;
+
+            $code_ref->($word, $correction);
+        }
+    }
+
+    # Special case for correcting multi-word strings.
+    for my $cm (@CORRECTIONS_MULTIWORD) {
+        my ($oregex, $correction) = @{$cm};
+        if ($text =~ $oregex) {
+            my $word = $1;
+            if ($word =~ /^[A-Z]+$/) {
+                $correction = uc $correction;
+            } elsif ($word =~ /^[A-Z]/) {
+                $correction = ucfirst $correction;
+            }
+            $counter++;
+            next if $seen{lc $word}++;
+            $code_ref->(
+                $DOUBLE_QUOTE . $word . $DOUBLE_QUOTE,
+                $DOUBLE_QUOTE . $correction . $DOUBLE_QUOTE
+            );
+        }
+    }
+
+    return $counter;
+}
+
+=item check_spelling_picky(TEXT, CODEREF)
+
+Performs a spelling check of TEXT.  Call CODEREF once for each unique
+misspelling with the following arguments:
+
+=over 4
+
+=item The misspelled word/phrase
+
+=item The correct word/phrase
+
+=back
+
+This method performs some pickier corrections - such as checking for common
+capitalization mistakes - which would are not included in check_spelling as
+they are not appropriate for some files, such as changelogs.
+
+Returns the number of spelling mistakes found in TEXT.
+
+=cut
+
+sub check_spelling_picky {
+    my ($data, $text, $code_ref) = @_;
+
+    croak encode_utf8('No spelling data')
+      unless defined $data;
+
+    my %seen;
+    my $counter = 0;
+    my $corrections_case= $data->load('spelling/corrections-case', '\|\|');
+
+    # Check this first in case it's contained in square brackets and
+    # removed below.
+    if ($text =~ /meta\s+package/) {
+        $counter++;
+        $code_ref->('meta package', 'metapackage');
+    }
+
+    # Exclude text enclosed in square brackets as it could be a package list
+    # or similar which may legitimately contain lower-cased versions of
+    # the words.
+    $text =~ s/\[.+?\]//sg;
+    $text =~ tr/\r\n \t/ /s;
+    $text =~ s/\s++/ /g;
+
+    # trim both ends
+    $text =~ s/^\s+|\s+$//g;
+
+    for my $word (split(/\s+/, $text)) {
+        $word =~ s/^\(|[).,?!:;]+$//g;
+        if ($corrections_case->recognizes($word)) {
+            $counter++;
+            next if $seen{$word}++;
+            $code_ref->($word, $corrections_case->value($word));
+        }
+    }
+
+    return $counter;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Russ Allbery <rra@debian.org> for Lintian.  Based on
+code from checks scripts by Marc Brockschmidt and Richard Braakman.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Storage/MLDBM.pm b/lib/Lintian/Storage/MLDBM.pm
new file mode 100644
index 0000000..f58cb8c
--- /dev/null
+++ b/lib/Lintian/Storage/MLDBM.pm
@@ -0,0 +1,128 @@
+# -*- perl -*- Lintian::Storage::MLDBM
+#
+# Copyright (C) 2022 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Storage::MLDBM;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use BerkeleyDB;
+use Const::Fast;
+use MLDBM qw(BerkeleyDB::Btree Storable);
+use Path::Tiny;
+use Syntax::Keyword::Try;
+use Unicode::UTF8 qw(encode_utf8 decode_utf8);
+
+const my $EMPTY => q{};
+const my $HYPHEN => q{-};
+
+use Moo;
+use namespace::clean;
+
+=head1 NAME
+
+Lintian::Storage::MLDBM - store multi-level hashes on disk
+
+=head1 SYNOPSIS
+
+    use Lintian::Storage::MLDBM;
+
+=head1 DESCRIPTION
+
+Lintian::Storage::MLDBM provides an interface to store data on disk to preserve memory.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item tempfile
+
+=item tied_hash
+
+=cut
+
+has tempfile => (is => 'rw');
+has tied_hash => (is => 'rw', default => sub { {} });
+
+=item create
+
+=cut
+
+sub create {
+    my ($self, $description) = @_;
+
+    $description //= $EMPTY;
+
+    $description .= $HYPHEN
+      if length $description;
+
+    my $stem = "mldbm-$description";
+
+    my $tempfile
+      = Path::Tiny->tempfile(TEMPLATE => $stem . 'XXXXXXXX', UNLINK => 0);
+    $self->tempfile($tempfile);
+
+    try {
+        tie(
+            %{$self->tied_hash}, 'MLDBM',
+            -Filename => $tempfile->stringify,
+            -Flags    => DB_CREATE
+        );
+
+    } catch {
+        die encode_utf8("Cannot create database in $tempfile: $@");
+    };
+
+    return;
+}
+
+=item DEMOLISH
+
+=cut
+
+sub DEMOLISH {
+    my ($self, $in_global_destruction) = @_;
+
+    untie %{$self->tied_hash};
+
+    $self->tempfile->remove
+      if defined $self->tempfile;
+
+    return;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for
+Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Tag.pm b/lib/Lintian/Tag.pm
new file mode 100644
index 0000000..7c93086
--- /dev/null
+++ b/lib/Lintian/Tag.pm
@@ -0,0 +1,297 @@
+# -*- perl -*-
+# Lintian::Tag -- interface to tag metadata
+
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2009 Russ Allbery
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the Free
+# Software Foundation; either version 2 of the License, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+# more details.
+#
+# You should have received a copy of the GNU General Public License along with
+# this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package Lintian::Tag;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp qw(croak);
+use Const::Fast;
+use Email::Address::XS;
+use List::SomeUtils qw(none first_value);
+use Syntax::Keyword::Try;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Deb822;
+
+use Moo;
+use namespace::clean;
+
+const my $EMPTY => q{};
+const my $SLASH => q{/};
+
+# Ordered lists of visibilities, used for display level parsing.
+our @VISIBILITIES= qw(classification pedantic info warning error);
+
+=head1 NAME
+
+Lintian::Tag - Lintian interface to tag metadata
+
+=head1 SYNOPSIS
+
+    my $tag = Lintian::Tag->new;
+
+=head1 DESCRIPTION
+
+This module provides an interface to tag metadata as gleaned from the
+*.desc files describing the checks.  It can be used to retrieve specific
+metadata elements or to format the tag description.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item name
+
+=item visibility
+
+=item check
+
+=item name_spaced
+
+=item show_always
+
+=item experimental
+
+=item explanation
+
+=item see_also
+
+=item renamed_from
+
+=item profile
+
+=cut
+
+has name => (
+    is => 'rw',
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); },
+    default => $EMPTY
+);
+
+has visibility => (
+    is => 'rw',
+    lazy => 1,
+    coerce => sub {
+        my ($text) = @_;
+
+        $text //= $EMPTY;
+        croak encode_utf8("Unknown tag visibility $text")
+          if none { $text eq $_ } @VISIBILITIES;
+
+        return $text;
+    },
+    default => $EMPTY
+);
+
+has check => (
+    is => 'rw',
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); },
+    default => $EMPTY
+);
+
+has name_spaced => (
+    is => 'rw',
+    coerce => sub { my ($boolean) = @_; return ($boolean // 0); },
+    default => 0
+);
+
+has show_always => (
+    is => 'rw',
+    coerce => sub { my ($boolean) = @_; return ($boolean // 0); },
+    default => 0
+);
+
+has experimental => (
+    is => 'rw',
+    coerce => sub { my ($boolean) = @_; return ($boolean // 0); },
+    default => 0
+);
+
+has explanation => (
+    is => 'rw',
+    coerce => sub { my ($text) = @_; return ($text // $EMPTY); },
+    default => $EMPTY
+);
+
+has see_also => (
+    is => 'rw',
+    coerce => sub { my ($arrayref) = @_; return ($arrayref // []); },
+    default => sub { [] }
+);
+
+has renamed_from => (
+    is => 'rw',
+    coerce => sub { my ($arrayref) = @_; return ($arrayref // []); },
+    default => sub { [] }
+);
+
+has screens => (
+    is => 'rw',
+    coerce => sub { my ($arrayref) = @_; return ($arrayref // []); },
+    default => sub { [] }
+);
+
+=item load(PATH)
+
+Loads a tag description from PATH.
+
+=cut
+
+sub load {
+    my ($self, $profile, $tagpath) = @_;
+
+    croak encode_utf8('No profile')
+      unless defined $profile;
+
+    croak encode_utf8("Cannot read tag file from $tagpath")
+      unless -r $tagpath;
+
+    my $deb822 = Lintian::Deb822->new;
+    my @sections = $deb822->read_file($tagpath);
+
+    my $fields = shift @sections;
+
+    $self->check($fields->value('Check'));
+    $self->name_spaced($fields->value('Name-Spaced') eq 'yes');
+    $self->show_always($fields->value('Show-Always') eq 'yes');
+
+    my $name = $fields->value('Tag');
+    $name = $self->check . $SLASH . $name
+      if $self->name_spaced;
+
+    $self->name($name);
+
+    $self->visibility($fields->value('Severity'));
+    $self->experimental($fields->value('Experimental') eq 'yes');
+
+    $self->explanation($fields->text('Explanation') || $fields->text('Info'));
+
+    my @see_also = $fields->trimmed_list('See-Also', qr{,});
+    @see_also = $fields->trimmed_list('Ref', qr{,})
+      unless @see_also;
+
+    $self->see_also(\@see_also);
+
+    $self->renamed_from([$fields->trimmed_list('Renamed-From')]);
+
+    croak encode_utf8("No Tag field in $tagpath")
+      unless length $self->name;
+
+    my @screens;
+    for my $section (@sections) {
+
+        my $screen_name = $section->value('Screen');
+
+        my $relative = $screen_name;
+        $relative =~ s{^([[:lower:]])}{\U$1};
+        $relative =~ s{/([[:lower:]])}{/\U$1}g;
+        $relative =~ s{-([[:lower:]])}{\U$1}g;
+
+        $relative .= '.pm';
+
+        my @candidates= map {
+            (
+                ($_ // q{.})."/lib/Lintian/Screen/$relative",
+                ($_ // q{.})."/screens/$relative"
+            )
+        } @{$profile->safe_include_dirs};
+
+        my $absolute = first_value { -e } @candidates;
+        die encode_utf8(
+            "Cannot find screen $screen_name (looking for $relative)")
+          unless length $absolute;
+
+        try {
+            require $absolute;
+        } catch {
+            die encode_utf8("Cannot load screen $absolute: $@");
+        }
+
+        my $module = $relative;
+        $module =~ s{ [.]pm $}{}x;
+        $module =~ s{/}{::}g;
+
+        my $screen = "Lintian::Screen::$module"->new;
+
+        $screen->name($screen_name);
+
+        my @advocates= Email::Address::XS->parse($section->value('Advocates'));
+        $screen->advocates(\@advocates);
+
+        $screen->reason($section->text('Reason'));
+
+        my @see_also_screen = $section->trimmed_list('See-Also', qr{,});
+        $screen->see_also(\@see_also_screen);
+
+        push(@screens, $screen);
+    }
+
+    $self->screens(\@screens);
+
+    return;
+}
+
+=item code()
+
+Returns the one-letter code for the tag.  This will be a letter chosen
+from C<E>, C<W>, C<I>, or C<P>, based on the tag visibility, and
+other attributes (such as whether experimental is set).  This code will
+never be C<O> or C<X>; overrides and experimental tags are handled
+separately.
+
+=cut
+
+# Map visibility levels to tag codes.
+our %CODES = (
+    'error' => 'E',
+    'warning' => 'W',
+    'info' => 'I',
+    'pedantic' => 'P',
+    'classification' => 'C',
+);
+
+sub code {
+    my ($self) = @_;
+
+    return $CODES{$self->visibility};
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Russ Allbery <rra@debian.org> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Util.pm b/lib/Lintian/Util.pm
new file mode 100644
index 0000000..c512451
--- /dev/null
+++ b/lib/Lintian/Util.pm
@@ -0,0 +1,674 @@
+# Hey emacs! This is a -*- Perl -*- script!
+# Lintian::Util -- Perl utility functions for lintian
+
+# Copyright (C) 1998 Christian Schwarz
+# Copyright (C) 2018-2019 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Util;
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+# Force export as soon as possible, since some of the modules we load also
+# depend on us and the sequencing can cause things not to be exported
+# otherwise.
+our @EXPORT_OK;
+
+BEGIN {
+
+    @EXPORT_OK = (
+        qw(
+          get_file_checksum
+          get_file_digest
+          human_bytes
+          perm2oct
+          locate_executable
+          match_glob
+          normalize_pkg_path
+          normalize_link_target
+          is_ancestor_of
+          drain_pipe
+          drop_relative_prefix
+          read_md5sums
+          utf8_clean_log
+          utf8_clean_bytes
+          version_from_changelog
+          $PKGNAME_REGEX
+          $PKGREPACK_REGEX
+          $PKGVERSION_REGEX
+        )
+    );
+}
+
+use Carp qw(croak);
+use Const::Fast;
+use Cwd qw(abs_path);
+use Digest::MD5;
+use Digest::SHA;
+use List::SomeUtils qw(first_value);
+use Path::Tiny;
+use Regexp::Wildcards;
+use Unicode::UTF8 qw(valid_utf8 encode_utf8);
+
+use Lintian::Deb822;
+use Lintian::Changelog;
+use Lintian::Relation::Version qw(versions_equal versions_comparator);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $NEWLINE => qq{\n};
+const my $SLASH => q{/};
+const my $DOT => q{.};
+const my $DOUBLEDOT => q{..};
+const my $BACKSLASH => q{\\};
+
+const my $DEFAULT_READ_SIZE => 4096;
+const my $KIB_UNIT_FACTOR => 1024;
+const my $COMFORT_THRESHOLD => 1536;
+
+const my $OWNER_READ => oct(400);
+const my $OWNER_WRITE => oct(200);
+const my $OWNER_EXECUTE => oct(100);
+const my $SETUID => oct(4000);
+const my $SETUID_OWNER_EXECUTE => oct(4100);
+const my $GROUP_READ => oct(40);
+const my $GROUP_WRITE => oct(20);
+const my $GROUP_EXECUTE => oct(10);
+const my $SETGID => oct(2000);
+const my $SETGID_GROUP_EXECUTE => oct(2010);
+const my $WORLD_READ => oct(4);
+const my $WORLD_WRITE => oct(2);
+const my $WORLD_EXECUTE => oct(1);
+const my $STICKY => oct(1000);
+const my $STICKY_WORLD_EXECUTE => oct(1001);
+
+# preload cache for common permission strings
+# call overhead o perm2oct was measurable on chromium-browser/32.0.1700.123-2
+# load time went from ~1.5s to ~0.1s; of 115363 paths, only 306 were uncached
+# standard file, executable file, standard dir, dir with suid, symlink
+my %OCTAL_LOOKUP = map { $_ => perm2oct($_) } qw(
+  -rw-r--r--
+  -rwxr-xr-x
+  drwxr-xr-x
+  drwxr-sr-x
+  lrwxrwxrwx
+);
+
+my $rw = Regexp::Wildcards->new(type => 'jokers');
+
+=head1 NAME
+
+Lintian::Util - Lintian utility functions
+
+=head1 SYNOPSIS
+
+ use Lintian::Util;
+
+=head1 DESCRIPTION
+
+This module contains a number of utility subs that are nice to have,
+but on their own did not warrant their own module.
+
+Most subs are imported only on request.
+
+=head1 VARIABLES
+
+=over 4
+
+=item $PKGNAME_REGEX
+
+Regular expression that matches valid package names.  The expression
+is not anchored and does not enforce any "boundary" characters.
+
+=cut
+
+our $PKGNAME_REGEX = qr/[a-z0-9][-+\.a-z0-9]+/;
+
+=item $PKGREPACK_REGEX
+
+Regular expression that matches "repacked" package names.  The expression is
+not anchored and does not enforce any "boundary" characters. It should only
+be applied to the upstream portion (see #931846).
+
+=cut
+
+our $PKGREPACK_REGEX = qr/(dfsg|debian|ds|repack)/;
+
+=item $PKGVERSION_REGEX
+
+Regular expression that matches valid package versions.  The
+expression is not anchored and does not enforce any "boundary"
+characters.
+
+=cut
+
+our $PKGVERSION_REGEX = qr{
+                 (?: \d+ : )?                # Optional epoch
+                 [0-9][0-9A-Za-z.+:~]*       # Upstream version (with no hyphens)
+                 (?: - [0-9A-Za-z.+:~]+ )*   # Optional debian revision (+ upstreams versions with hyphens)
+                          }xa;
+
+=back
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item drain_pipe(FD)
+
+Reads and discards any remaining contents from FD, which is assumed to
+be a pipe.  This is mostly done to avoid having the "write"-end die
+with a SIGPIPE due to a "broken pipe" (which can happen if you just
+close the pipe).
+
+May cause an exception if there are issues reading from the pipe.
+
+Caveat: This will block until the pipe is closed from the "write"-end,
+so only use it with pipes where the "write"-end will eventually close
+their end by themselves (or something else will make them close it).
+
+=cut
+
+sub drain_pipe {
+    my ($fd) = @_;
+    my $buffer;
+
+    1 while (read($fd, $buffer, $DEFAULT_READ_SIZE) > 0);
+
+    return 1;
+}
+
+=item get_file_digest(ALGO, FILE)
+
+Creates an ALGO digest object that is seeded with the contents of
+FILE.  If you just want the hex digest, please use
+L</get_file_checksum(ALGO, FILE)> instead.
+
+ALGO can be 'md5' or shaX, where X is any number supported by
+L<Digest::SHA> (e.g. 'sha256').
+
+This sub is a convenience wrapper around Digest::{MD5,SHA}.
+
+=cut
+
+sub get_file_digest {
+    my ($alg, $file) = @_;
+
+    open(my $fd, '<', $file)
+      or die encode_utf8("Cannot open $file");
+
+    my $digest;
+    if (lc($alg) eq 'md5') {
+        $digest = Digest::MD5->new;
+    } elsif (lc($alg) =~ /sha(\d+)/) {
+        $digest = Digest::SHA->new($1);
+    }
+    $digest->addfile($fd);
+    close($fd);
+
+    return $digest;
+}
+
+=item get_file_checksum(ALGO, FILE)
+
+Returns a hexadecimal string of the message digest checksum generated
+by the algorithm ALGO on FILE.
+
+ALGO can be 'md5' or shaX, where X is any number supported by
+L<Digest::SHA> (e.g. 'sha256').
+
+This sub is a convenience wrapper around Digest::{MD5,SHA}.
+
+=cut
+
+sub get_file_checksum {
+    my @paths = @_;
+
+    my $digest = get_file_digest(@paths);
+
+    return $digest->hexdigest;
+}
+
+=item perm2oct(PERM)
+
+Translates PERM to an octal permission.  PERM should be a string describing
+the permissions as done by I<tar t> or I<ls -l>.  That is, it should be a
+string like "-rw-r--r--".
+
+If the string does not appear to be a valid permission, it will cause
+a trappable error.
+
+Examples:
+
+ # Good
+ perm2oct('-rw-r--r--') == oct(644)
+ perm2oct('-rwxr-xr-x') == oct(755)
+
+ # Bad
+ perm2oct('broken')      # too short to be recognised
+ perm2oct('-resurunet')  # contains unknown permissions
+
+=cut
+
+sub perm2oct {
+    my ($text) = @_;
+
+    my $lookup = $OCTAL_LOOKUP{$text};
+    return $lookup
+      if defined $lookup;
+
+    my $octal = 0;
+
+    # Types:
+    #  file (-), block/character device (b & c), directory (d),
+    #  hardlink (h), symlink (l), named pipe (p).
+    if (
+        $text !~ m{^   [-bcdhlp]                # file type
+                    ([-r])([-w])([-xsS])     # user
+                    ([-r])([-w])([-xsS])     # group
+                    ([-r])([-w])([-xtT])     # other
+               }xsm
+    ) {
+        croak encode_utf8("$text does not appear to be a permission string");
+    }
+
+    $octal |= $OWNER_READ if $1 eq 'r';
+    $octal |= $OWNER_WRITE if $2 eq 'w';
+    $octal |= $OWNER_EXECUTE if $3 eq 'x';
+    $octal |= $SETUID if $3 eq 'S';
+    $octal |= $SETUID_OWNER_EXECUTE if $3 eq 's';
+    $octal |= $GROUP_READ if $4 eq 'r';
+    $octal |= $GROUP_WRITE if $5 eq 'w';
+    $octal |= $GROUP_EXECUTE if $6 eq 'x';
+    $octal |= $SETGID if $6 eq 'S';
+    $octal |= $SETGID_GROUP_EXECUTE if $6 eq 's';
+    $octal |= $WORLD_READ if $7 eq 'r';
+    $octal |= $WORLD_WRITE if $8 eq 'w';
+    $octal |= $WORLD_EXECUTE if $9 eq 'x';
+    $octal |= $STICKY if $9 eq 'T';
+    $octal |= $STICKY_WORLD_EXECUTE if $9 eq 't';
+
+    $OCTAL_LOOKUP{$text} = $octal;
+
+    return $octal;
+}
+
+=item human_bytes(SIZE)
+
+=cut
+
+sub human_bytes {
+    my ($size) = @_;
+
+    my @units = qw(B kiB MiB GiB);
+
+    my $unit = shift @units;
+
+    while ($size > $COMFORT_THRESHOLD && @units) {
+
+        $size /= $KIB_UNIT_FACTOR;
+        $unit = shift @units;
+    }
+
+    my $human = sprintf('%.0f %s', $size, $unit);
+
+    return $human;
+}
+
+=item locate_executable (CMD)
+
+=cut
+
+sub locate_executable {
+    my ($command) = @_;
+
+    return $EMPTY
+      unless exists $ENV{PATH};
+
+    my @folders =  grep { length } split(/:/, $ENV{PATH});
+    my $path = first_value { -x "$_/$command" } @folders;
+
+    return ($path // $EMPTY);
+}
+
+=item drop_relative_prefix(STRING)
+
+Remove an initial ./ from STRING, if present
+
+=cut
+
+sub drop_relative_prefix {
+    my ($name) = @_;
+
+    my $copy = $name;
+    $copy =~ s{^\./}{}s;
+
+    return $copy;
+}
+
+=item version_from_changelog
+
+=cut
+
+sub version_from_changelog {
+    my ($package_path) = @_;
+
+    my $changelog_path = "$package_path/debian/changelog";
+
+    return $EMPTY
+      unless -e $changelog_path;
+
+    my $contents = path($changelog_path)->slurp_utf8;
+    my $changelog = Lintian::Changelog->new;
+
+    $changelog->parse($contents);
+    my @entries = @{$changelog->entries};
+
+    return $entries[0]->{'Version'}
+      if @entries;
+
+    return $EMPTY;
+}
+
+=item match_glob( $glob, @things_to_test )
+
+Resembles the same semantic as Text::Glob's match_glob(), but with the
+proper escaping of Regexp::Wildcards and pre-configured for Lintian's
+purpose. No more directly having to access module variables either.
+
+=cut
+
+sub match_glob {
+    my ($glob, @things_to_test) = @_;
+    my $re = $rw->convert($glob);
+
+    return grep { /^$re\z/ } @things_to_test;
+}
+
+=item normalize_pkg_path(PATH)
+
+Normalize PATH by removing superfluous path segments.  PATH is assumed
+to be relative the package root.  Note that the result will never
+start nor end with a slash, even if PATH does.
+
+As the name suggests, this is a path "normalization" rather than a
+true path resolution (for that use Cwd::realpath).  Particularly,
+it assumes none of the path segments are symlinks.
+
+normalize_pkg_path will return C<q{}> (i.e. the empty string) if PATH
+is normalized to the root dir and C<undef> if the path cannot be
+normalized without escaping the package root.
+
+=item normalize_link_target(CURDIR, LINK_TARGET)
+
+Normalize the path obtained by following a link with LINK_TARGET as
+its target from CURDIR as the current directory.  CURDIR is assumed to
+be relative to the package root.  Note that the result will never
+start nor end with a slash, even if CURDIR or DEST does.
+
+normalize_pkg_path will return C<q{}> (i.e. the empty string) if the
+target is the root dir and C<undef> if the path cannot be normalized
+without escaping the package root.
+
+B<CAVEAT>: This function is I<not always sufficient> to test if it is
+safe to open a given symlink. Use C<is_ancestor_of(PARENTDIR, PATH)> for
+that.  If you must use this function, remember to check that the
+target is not a symlink (or if it is, that it can be resolved safely).
+
+=cut
+
+sub normalize_link_target {
+    my ($path, $target) = @_;
+
+    if (substr($target, 0, 1) eq $SLASH) {
+        # Link is absolute
+        $path = $target;
+    } else {
+        # link is relative
+        $path = "$path/$target";
+    }
+
+    return normalize_pkg_path($path);
+}
+
+sub normalize_pkg_path {
+    my ($path) = @_;
+
+    return $EMPTY
+      if $path eq $SLASH;
+
+    my @dirty = split(m{/}, $path);
+    my @clean = grep { length } @dirty;
+
+    my @final;
+    for my $component (@clean) {
+
+        if ($component eq $DOT) {
+            # do nothing
+
+        } elsif ($component eq $DOUBLEDOT) {
+            # are we out of bounds?
+            my $discard = pop @final;
+            return undef
+              unless defined $discard;
+
+        } else {
+            push(@final, $component);
+        }
+    }
+
+    # empty if we end in the root
+    my $normalized = join($SLASH, @final);
+
+    return $normalized;
+}
+
+=item is_ancestor_of(PARENTDIR, PATH)
+
+Returns true if and only if PATH is PARENTDIR or a path stored
+somewhere within PARENTDIR (or its subdirs).
+
+This function will resolve the paths; any failure to resolve the path
+will cause a trappable error.
+
+=cut
+
+sub is_ancestor_of {
+    my ($ancestor, $file) = @_;
+
+    my $resolved_file = abs_path($file);
+    croak encode_utf8("resolving $file failed: $!")
+      unless defined $resolved_file;
+
+    my $resolved_ancestor = abs_path($ancestor);
+    croak encode_utf8("resolving $ancestor failed: $!")
+      unless defined $resolved_ancestor;
+
+    my $len;
+    return 1 if $resolved_ancestor eq $resolved_file;
+    # add a slash, "path/some-dir" is not "path/some-dir-2" and this
+    # allows us to blindly match against the root dir.
+    $resolved_file .= $SLASH;
+    $resolved_ancestor .= $SLASH;
+
+    # If $resolved_file is contained within $resolved_ancestor, then
+    # $resolved_ancestor will be a prefix of $resolved_file.
+    $len = length($resolved_ancestor);
+    if (substr($resolved_file, 0, $len) eq $resolved_ancestor) {
+        return 1;
+    }
+    return 0;
+}
+
+=item read_md5sums
+
+=item unescape_md5sum_filename
+
+=cut
+
+sub unescape_md5sum_filename {
+    my ($string, $problematic) = @_;
+
+    # done if there are no escapes
+    return $string
+      unless $problematic;
+
+    # split into individual characters
+    my @array = split(//, $string);
+
+# https://www.gnu.org/software/coreutils/manual/html_node/md5sum-invocation.html
+    my $path;
+    my $escaped = 0;
+    for my $char (@array) {
+
+        # start escape sequence
+        if ($char eq $BACKSLASH && !$escaped) {
+            $escaped = 1;
+            next;
+        }
+
+        # unescape newline
+        $char = $NEWLINE
+          if $char eq 'n' && $escaped;
+
+        # append character
+        $path .= $char;
+
+        # end any escape sequence
+        $escaped = 0;
+    }
+
+    # do not stop inside an escape sequence
+    die encode_utf8('Name terminated inside an escape sequence')
+      if $escaped;
+
+    return $path;
+}
+
+sub read_md5sums {
+    my ($text) = @_;
+
+    my %checksums;
+    my @errors;
+
+    my @lines = split(/\n/, $text);
+
+    while (defined(my $line = shift @lines)) {
+
+        next
+          unless length $line;
+
+        # make sure there are two spaces in between
+        $line =~ /^((?:\\)?\S{32})  (.*)$/;
+
+        my $checksum = $1;
+        my $string = $2;
+
+        unless (length $checksum && length $string) {
+
+            push(@errors, "Odd text: $line");
+            next;
+        }
+
+        my $problematic = 0;
+
+        # leading slash in checksum indicates an escaped name
+        $problematic = 1
+          if $checksum =~ s{^\\}{};
+
+        my $path = unescape_md5sum_filename($string, $problematic);
+
+        push(@errors, "Empty name for checksum $checksum")
+          unless length $path;
+
+        $checksums{$path} = $checksum;
+    }
+
+    return (\%checksums, \@errors);
+}
+
+=item utf8_clean_log
+
+=cut
+
+sub utf8_clean_log {
+    my ($bytes) = @_;
+
+    my $hex_sequence = sub {
+        my ($unclean_bytes) = @_;
+        return '{hex:' . sprintf('%vX', $unclean_bytes) . '}';
+    };
+
+    my $utf8_clean_word = sub {
+        my ($word) = @_;
+        return utf8_clean_bytes($word, $SLASH, $hex_sequence);
+    };
+
+    my $utf8_clean_line = sub {
+        my ($line) = @_;
+        return utf8_clean_bytes($line, $SPACE, $utf8_clean_word);
+    };
+
+    return utf8_clean_bytes($bytes, $NEWLINE, $utf8_clean_line) . $NEWLINE;
+}
+
+=item utf8_clean_bytes
+
+=cut
+
+sub utf8_clean_bytes {
+    my ($bytes, $separator, $utf8_clean_part) = @_;
+
+    my @utf8_clean_parts;
+
+    my $regex = quotemeta($separator);
+    my @parts = split(/$regex/, $bytes);
+
+    for my $part (@parts) {
+
+        if (valid_utf8($part)) {
+            push(@utf8_clean_parts, $part);
+
+        } else {
+            push(@utf8_clean_parts, $utf8_clean_part->($part));
+        }
+    }
+
+    return join($separator, @utf8_clean_parts);
+}
+
+=back
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Lintian/Version.pm b/lib/Lintian/Version.pm
new file mode 100644
index 0000000..959804f
--- /dev/null
+++ b/lib/Lintian/Version.pm
@@ -0,0 +1,122 @@
+#
+# Copyright (C) 1998 Christian Schwarz and Richard Braakman
+# Copyright (C) 2013 Niels Thykier
+# Copyright (C) 2017 Chris Lamb <lamby@debian.org>
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Lintian::Version;
+
+use v5.20;
+use warnings;
+use utf8;
+
+our @EXPORT_OK = (
+    qw(
+      guess_version
+    )
+);
+
+use Exporter qw(import);
+
+use Const::Fast;
+use Unicode::UTF8 qw(decode_utf8);
+
+use Lintian::IPC::Run3 qw(safe_qx);
+use Lintian::Util qw(version_from_changelog);
+
+const my $EMPTY => q{};
+
+=head1 NAME
+
+Lintian::Version - routines to determine Lintian version
+
+=head1 SYNOPSIS
+
+ use Lintian::Version;
+
+=head1 DESCRIPTION
+
+Lintian::Version can help guess the current Lintian version.
+
+=head1 INSTANCE METHODS
+
+=over 4
+
+=item guess_version
+
+=cut
+
+sub guess_version {
+    my ($lintian_base) = @_;
+
+    my $guess = version_from_git($lintian_base);
+    $guess ||= version_from_changelog($lintian_base);
+
+    return $guess;
+}
+
+=item version_from_git
+
+=cut
+
+sub version_from_git {
+    my ($source_path) = @_;
+
+    my $git_path = "$source_path/.git";
+
+    return $EMPTY
+      unless -d $git_path;
+
+    # Example outputs:
+    # 2.115.3-49-g086a9a113
+    # 2.115.3-49-g086a9a113-dirty
+    my $describe = decode_utf8(
+        safe_qx('git', "--git-dir=$git_path", 'describe', '--dirty'));
+    chomp $describe;
+
+    # Modify it to make it a valid native version number and make it
+    # look more debianish like these:
+    # 2.115.3+49commits+git086a9a113
+    # 2.115.3+49commits+git086a9a113+dirty
+    my $guess = $describe;
+    $guess =~ s/ - ( \d+ ) -g /+${1}commits+git/sx;
+    $guess =~ s/ - /+/sxg;
+
+    return ($guess // $EMPTY);
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Niels Thykier <niels@thykier.net> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Test/Lintian.pm b/lib/Test/Lintian.pm
new file mode 100644
index 0000000..4bcf72b
--- /dev/null
+++ b/lib/Test/Lintian.pm
@@ -0,0 +1,697 @@
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2012 Niels Thykier
+# Copyright (C) 2018 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Test::Lintian;
+
+=head1 NAME
+
+Test::Lintian -- Check Lintian files for issues
+
+=head1 SYNOPSIS
+
+ # file 1
+ use Test::Lintian;
+ use Test::More import => ['done_testing'];
+ test_load_profiles('some/path');
+
+ done_testing;
+
+ # file 2
+ use Test::Lintian;
+ use Test::More import => ['done_testing'];
+ load_profile_for_test('vendor/profile', 'some/path', '/usr/share/lintian');
+ test_check_desc('some/path/checks');
+ test_load_checks('some/path/checks');
+ test_tags_implemented('some/path/checks');
+
+ done_testing;
+
+=head1 DESCRIPTION
+
+A testing framework for testing various Lintian files for common
+errors.
+
+=cut
+
+use v5.20;
+use warnings;
+use utf8;
+
+my $CLASS = __PACKAGE__;
+my $PROFILE;
+our @EXPORT = qw(
+  load_profile_for_test
+
+  test_check_desc
+  test_load_checks
+  test_load_profiles
+
+  program_name_to_perl_paths
+);
+
+use parent 'Test::Builder::Module';
+
+use Cwd qw(realpath);
+use Const::Fast;
+use File::Basename qw(basename);
+use File::Find ();
+use List::SomeUtils qw{any};
+use Path::Tiny;
+use Syntax::Keyword::Try;
+use Unicode::UTF8 qw(valid_utf8 decode_utf8 encode_utf8);
+
+use Lintian::Spelling qw(check_spelling);
+use Lintian::Deb822;
+use Lintian::Profile;
+use Lintian::Tag;
+
+const my $EMPTY => q{};
+const my $COLON => q{:};
+const my $MAXIMUM_TAG_LENGTH => 68;
+
+my %visibilities = map { $_ => 1 } @Lintian::Tag::VISIBILITIES;
+my %check_types = map { $_ => 1 } qw(binary changes source udeb);
+my %known_html_tags = map { $_ => 1 } qw(a em i tt);
+
+# lazy-load this (so loading a profile can affect it)
+my %URLS;
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item test_check_desc(OPTS, CHECKS...)
+
+Test check desc files (and the tags in them) for common errors.
+
+OPTS is a HASHREF containing key/value pairs, which are
+described below.
+
+CHECKS is a list of paths in which to check desc files.  Any given
+element in CHECKS can be either a file or a dir.  Files are assumed to
+be check desc file.  Directories are searched and all I<.desc> files
+in those dirs are processed.
+
+As the number of tests depends on the number of tags in desc, it is
+difficult to "plan ahead" when using this test.  It is therefore
+recommended to not specify a plan and use done_testing().
+
+This sub uses a Data file (see L</load_profile_for_test ([PROFNAME[, INC...]])>).
+
+OPTS may contain the following key/value pairs:
+
+=over 4
+
+=item filter
+
+If defined, it is a filter function that examines $_ (or its first
+argument) and returns a truth value if C<$_> should be considered or
+false otherwise.  C<$_> will be the path to the current file (or dir)
+in question; it may be relative or absolute.
+
+NB: I<all> elements in CHECKS are subject to the filter.
+
+CAVEAT: If the filter rejects a directory, none of the files in it will be
+considered either.  Even if the filter accepts a file, that file will
+only be processed if it has the proper extension (i.e. with I<.desc>).
+
+=item translation
+
+If defined and a truth value, the desc files are expected to contain
+translations.  Otherwise, they must be regular checks.
+
+=back
+
+=cut
+
+sub test_check_desc {
+    my ($opts, @dirs) = @_;
+
+    my $builder = $CLASS->builder;
+    my $colldir = '/usr/share/lintian/collection';
+    my $find_opt = {'filter' => undef,};
+    my $tested = 0;
+
+    $find_opt->{'filter'} = $opts->{'filter'}
+      if exists $opts->{'filter'};
+
+    $opts //= {};
+
+    load_profile_for_test();
+
+    my @descs = map { _find_check($find_opt, $_) } @dirs;
+    foreach my $desc_file (@descs) {
+
+        my $bytes = path($desc_file)->slurp;
+        $builder->ok(valid_utf8($bytes),
+            "File $desc_file does not use a national encoding.");
+        next
+          unless valid_utf8($bytes);
+
+        my $deb822 = Lintian::Deb822->new;
+
+        my @sections;
+        try {
+            @sections = $deb822->read_file($desc_file);
+
+        } catch {
+            my $err = $@;
+            $err =~ s/ at .*? line \d+\s*\n//;
+            $builder->ok(0, "Cannot parse $desc_file");
+            $builder->diag("Error: $err");
+            next;
+        }
+
+        my ($header, @tagpara) = @sections;
+
+        my $content_type = 'Check';
+        my $cname = $header->value('Check-Script');
+        my $ctype = $header->value('Type');
+        my $i = 1; # paragraph counter.
+        $builder->ok(1, "Can parse check $desc_file");
+
+        $builder->isnt_eq($cname, $EMPTY,
+            "$content_type has a name ($desc_file)");
+
+        # From here on, we just use "$cname" as name of the check, so
+        # we don't need to choose been it and $tname.
+        $cname = '<missing>' if $cname eq $EMPTY;
+        $tested += 2;
+
+        if ($cname eq 'lintian') {
+            my $reason = 'check "lintian" does not have a type';
+            # skip these two tests for this special case...
+            $builder->skip("Special case, $reason");
+            $builder->skip("Special case, $reason");
+        } elsif ($builder->isnt_eq($ctype, $EMPTY, "$cname has a type")) {
+            my @bad;
+            # new lines are not allowed, map them to "\\n" for readability.
+            $ctype =~ s/\n/\\n/g;
+            foreach my $type (split /\s*+,\s*+/, $ctype) {
+                push @bad, $type unless exists $check_types{$type};
+            }
+            $builder->is_eq(join(', ', @bad),
+                $EMPTY,"The type of $cname is valid");
+        } else {
+            $builder->skip(
+                "Cannot check type of $cname is valid (field is empty/missing)"
+            );
+        }
+
+        for my $tpara (@tagpara) {
+
+            my $tag = $tpara->value('Tag');
+            my $visibility = $tpara->value('Severity');
+            my $explanation = $tpara->value('Explanation');
+
+            my (@htmltags, %seen);
+
+            $i++;
+
+            # Tag name
+            $builder->isnt_eq($tag, $EMPTY, "Tag in check $cname has a name")
+              or $builder->diag("$cname: Paragraph number $i\n");
+            $tag = '<N/A>' if $tag eq $EMPTY;
+            $builder->ok($tag =~ /^[\w0-9.+-]+$/, 'Tag has valid characters')
+              or $builder->diag("$cname: $tag\n");
+            $builder->cmp_ok(length $tag, '<=', $MAXIMUM_TAG_LENGTH,
+                'Tag is not too long')
+              or $builder->diag("$cname: $tag\n");
+
+            # Visibility
+            $builder->ok($visibility && exists $visibilities{$visibility},
+                'Tag has valid visibility')
+              or $builder->diag("$cname: $tag visibility: $visibility\n");
+
+            # Explanation
+            my $mistakes = 0;
+            my $handler = sub {
+                my ($incorrect, $correct) = @_;
+                $builder->diag(
+                    "Spelling ($cname/$tag): $incorrect => $correct");
+                $mistakes++;
+            };
+            # FIXME: There are a couple of known false-positives that
+            # breaks the test.
+            # check_spelling($profile, $explanation, $handler);
+            $builder->is_eq($mistakes, 0,
+                "$content_type $cname: $tag has no spelling errors");
+
+            $builder->ok(
+                $explanation !~ /(?:^| )(?:[Ww]e|I)\b/,
+                'Tag explanation does not speak of "I", or "we"'
+            )or $builder->diag("$content_type $cname: $tag\n");
+
+            $builder->ok(
+                $explanation !~ /(\S\w)\. [^ ]/
+                  || $1 =~ /^\.[ge]$/, # for 'e.g.'/'i.e.'
+                'Tag explanation uses two spaces after a full stop'
+            ) or $builder->diag("$content_type $cname: $tag\n");
+
+            $builder->ok($explanation !~ /(\S\w\.   )/,
+                'Tag explanation uses only two spaces after a full stop')
+              or $builder->diag("$content_type $cname: $tag ($1)\n");
+
+            $builder->ok(valid_utf8($explanation),
+                'Tag explanation must be written in UTF-8')
+              or $builder->diag("$content_type $cname: $tag\n");
+
+            # Check the tag explanation for unescaped <> or for unknown tags
+            # (which probably indicate the same thing).
+            while ($explanation
+                =~ s{<([^\s>]+)(?:\s+href=\"[^\"]+\")?>.*?</\1>}{}s){
+                push @htmltags, $1;
+            }
+            @htmltags
+              = grep { !exists $known_html_tags{$_} && !$seen{$_}++ }@htmltags;
+            $builder->is_eq(join(', ', @htmltags),
+                $EMPTY, 'Tag explanation has no unknown html tags')
+              or $builder->diag("$content_type $cname: $tag\n");
+
+            $builder->ok($explanation !~ /[<>]/,
+                'Tag explanation has no stray angle brackets')
+              or $builder->diag("$content_type $cname: $tag\n");
+
+            if ($tpara->declares('See-Also')) {
+
+                my @issues = map { _check_reference($_) }
+                  $tpara->trimmed_list('See-Also', qr{ \s* , \s* }x);
+
+                my $text = join("\n\t", @issues);
+
+                $builder->ok(!@issues, 'Proper references are used')
+                  or $builder->diag("$content_type $cname: $tag\n\t$text");
+            }
+        }
+    }
+
+    $builder->cmp_ok($tested, '>', 0, 'Tested at least one desc file')
+      if @descs;
+    return;
+}
+
+=item test_load_profiles(ROOT, INC...)
+
+Test that all profiles in I<ROOT/profiles> are loadable.  INC will be
+the INC path used as include path for the profile.
+
+If INC is omitted, then the include path will consist of (ROOT,
+'/usr/share/lintian').  Otherwise, INC will be used as is (and should
+include ROOT).
+
+This sub will do one test per profile loaded.
+
+=cut
+
+sub test_load_profiles {
+    my ($dir, @inc) = @_;
+
+    my $builder = $CLASS->builder;
+    my $absdir = realpath $dir;
+    my $sre;
+    my %opt = ('no_chdir' => 1,);
+
+    if (not defined $absdir) {
+        die encode_utf8("$dir cannot be resolved: $!");
+    }
+
+    $absdir = "$absdir/profiles";
+    $sre = qr{\Q$absdir\E/};
+
+    @inc = ($absdir, '/usr/share/lintian') unless @inc;
+
+    $opt{'wanted'} = sub {
+        my $profname = $File::Find::name;
+
+        return
+          unless $profname =~ s/\.profile$//;
+        $profname =~ s/^$sre//;
+
+        my $profile = Lintian::Profile->new;
+
+        try {
+            $profile->load($profname, \@inc, 0);
+
+        } catch {
+            $builder->diag("Load error: $@\n");
+            $profile = 0;
+        }
+
+        $builder->ok($profile, "$profname is loadable.");
+    };
+
+    File::Find::find(\%opt, $absdir);
+    return;
+}
+
+=item test_load_checks(OPTS, DIR[, CHECKNAMES...])
+
+Test that the Perl module implementation of the checks can be loaded
+and has a run sub.
+
+OPTS is a HASHREF containing key/value pairs, which are
+described below.
+
+DIR is the directory where the checks can be found.
+
+CHECKNAMES is a list of check names.  If CHECKNAMES is given, only the
+checks in this list will be processed.  Otherwise, all the checks in
+DIR will be processed.
+
+For planning purposes, every check processed counts for 2 tests and
+the call itself does on additional check.  So if CHECKNAMES contains
+10 elements, then 21 tests will be done (2 * 10 + 1).  Filtered out
+checks will I<not> be counted.
+
+All data files created at compile time or in the file scope will be
+loaded immediately (instead of lazily as done during the regular
+runs).  This is done to spot missing data files or typos in their
+names.  Therefore, this sub will load a profile if one hasn't been
+loaded already.  (see L</load_profile_for_test ([PROFNAME[,
+INC...]])>)
+
+OPTS may contain the following key/value pairs:
+
+=over 4
+
+=item filter
+
+If defined, it is a filter function that examines $_ (or its first
+argument) and returns a truth value if C<$_> should be considered or
+false otherwise.  C<$_> will be the path to the current file (or dir)
+in question; it may be relative or absolute.
+
+NB: filter is I<not> used if CHECKNAMES is given.
+
+CAVEAT: If the filter rejects a directory, none of the files in it will be
+considered either.  Even if the filter accepts a file, that file will
+only be processed if it has the proper extension (i.e. with I<.desc>).
+
+=back
+
+=cut
+
+sub test_load_checks {
+    my ($opts, $dir, @check_names) = @_;
+
+    my $builder = $CLASS->builder;
+
+    unless (@check_names) {
+        my $find_opt = {'want-check-name' => 1,};
+        $find_opt->{'filter'} = $opts->{'filter'} if exists $opts->{'filter'};
+        @check_names = _find_check($find_opt, $dir);
+    } else {
+        $builder->skip('Given an explicit list of checks');
+    }
+
+    $builder->skip('No desc files found')
+      unless @check_names;
+
+    my $profile = load_profile_for_test();
+
+    foreach my $check_name (@check_names) {
+
+        my $path = $profile->check_path_by_name->{$check_name};
+        try {
+            require $path;
+
+        } catch {
+            $builder->skip(
+"Cannot check if $check_name has entry points due to load error"
+            );
+            next;
+        }
+
+        $builder->ok(1, "Check $check_name can be loaded");
+
+        my $module = $profile->check_module_by_name->{$check_name};
+
+        $builder->diag(
+            "Warning: check $check_name uses old entry point ::run\n")
+          if $module->can('run') && !$module->DOES('Lintian::Check');
+
+        # setup and breakdown should only be used together with files
+        my $has_entrypoint = any { $module->can($_) }
+          qw(source binary udeb installable changes always files);
+
+        if (
+            !$builder->ok(
+                $has_entrypoint, "Check $check_name has entry point"
+            )
+        ){
+            $builder->diag("Expected package name is $module\n");
+        }
+    }
+    return;
+}
+
+=item load_profile_for_test ([PROFNAME[, INC...]])
+
+Load a Lintian::Profile and ensure Data files can be used.  This is
+needed if the test needs to access a data file or if a special profile
+is needed for the test.  It does I<not> test the profile for issues.
+
+PROFNAME is the name of the profile to load.  It can be omitted, in
+which case the sub ensures that a profile has been loaded.  If no
+profile has been loaded, 'debian/main' will be loaded.
+
+INC is a list of extra "include dirs" (or Lintian "roots") to be used
+for finding the profile.  If not specified, it defaults to
+I<$ENV{'LINTIAN_BASE'}> and I</usr/share/lintian> (in order).
+INC is ignored if a profile has already been loaded.
+
+CAVEAT: Only one profile can be loaded in a given test.  Once a
+profile has been loaded, it is not possible to replace it with another
+one.  So if this is invoked multiple times, PROFNAME must be omitted
+or must match the name of the loaded profile.
+
+=cut
+
+sub load_profile_for_test {
+    my ($profname, @inc) = @_;
+
+    # We have loaded a profile and are not asked to
+    # load a specific one - then current one will do.
+    return $PROFILE
+      if $PROFILE and not $profname;
+
+    die encode_utf8("Cannot load two profiles.\n")
+      if $PROFILE and $PROFILE->name ne $profname;
+
+    # Already loaded? stop here
+    # We just need it for spell checking, so debian/main should
+    # do just fine...
+    return $PROFILE
+      if $PROFILE;
+
+    $profname ||= 'debian/main';
+
+    $PROFILE = Lintian::Profile->new;
+    $PROFILE->load($profname, [@inc, $ENV{'LINTIAN_BASE'}]);
+
+    $ENV{'LINTIAN_CONFIG_DIRS'} = join($COLON, @inc);
+
+    return $PROFILE;
+}
+
+sub _check_reference {
+    my ($see_also) = @_;
+
+    my @issues;
+
+    my @MARKDOWN_CAPABLE = (
+        $PROFILE->menu_policy,
+        $PROFILE->perl_policy,
+        $PROFILE->python_policy,
+        $PROFILE->java_policy,
+        $PROFILE->vim_policy,
+        $PROFILE->lintian_manual,
+        $PROFILE->developer_reference,
+        $PROFILE->policy_manual,
+        $PROFILE->debconf_specification,
+        $PROFILE->menu_specification,
+        $PROFILE->doc_base_specification,
+        $PROFILE->filesystem_hierarchy_standard,
+    );
+
+    my %by_shorthand = map { $_->shorthand => $_ } @MARKDOWN_CAPABLE;
+
+    # We use this to check for explicit links where it is possible to use
+    # a manual ref.
+    unless (%URLS) {
+        for my $manual (@MARKDOWN_CAPABLE) {
+
+            my $volume = $manual->shorthand;
+
+            for my $section_key ($manual->all){
+                my $entry = $manual->value($section_key);
+
+                my $url = $entry->{$section_key}{url};
+                next
+                  unless length $url;
+
+                $URLS{$url} = "$volume $section_key";
+            }
+        }
+    }
+
+    if (   $see_also =~ m{^https?://bugs.debian.org/(\d++)$}
+        || $see_also
+        =~ m{^https?://bugs.debian.org/cgi-bin/bugreport.cgi\?/.*bug=(\d++).*$}
+    ) {
+        push(@issues, "replace '$see_also' with '#$1'");
+
+    } elsif (exists $URLS{$see_also}) {
+        push(@issues, "replace '$see_also' with '$URLS{$see_also}'");
+
+    } elsif ($see_also =~ m/^([\w-]++)\s++(\S++)$/) {
+
+        my $volume = $1;
+        my $section = $2;
+
+        if (exists $by_shorthand{$volume}) {
+
+            my $manual = $by_shorthand{$volume};
+
+            push(@issues, "unknown section '$section' in $volume")
+              unless length $manual->markdown_citation($section);
+
+        } else {
+            push(@issues, "unknown manual '$volume'");
+        }
+
+    } else {
+        # Check it is a valid reference like URLs or #123456
+        # NB: "policy 10.1" references already covered above
+        push(@issues, "unknown or malformed reference '$see_also'")
+          if $see_also !~ /^#\d+$/ # debbugs reference
+          && $see_also !~ m{^(?:ftp|https?)://} # browser URL
+          && $see_also !~ m{^/} # local file reference
+          && $see_also !~ m{[\w_-]+\(\d\w*\)$}; # man reference
+    }
+
+    return @issues;
+}
+
+sub _find_check {
+    my ($find_opt, $input) = @_;
+    $find_opt//= {};
+    my $filter = $find_opt->{'filter'};
+
+    if ($filter) {
+        local $_ = $input;
+        # filtered out?
+        return () unless $filter->($_);
+    }
+
+    if (-d $input) {
+        my (@result, $regex);
+        if ($find_opt->{'want-check-name'}) {
+            $regex = qr{^\Q$input\E/*};
+        }
+        my $wanted = sub {
+            if (defined $filter) {
+                local $_ = $_;
+                if (not $filter->($_)) {
+                    # filtered out; if a dir - filter the
+                    # entire dir.
+                    $File::Find::prune = 1 if -d;
+                    return;
+                }
+            }
+            return unless m/\.desc$/ and -e;
+            if ($regex) {
+                s/$regex//;
+                s/\.desc$//;
+            }
+            push @result, $_;
+        };
+        my $opt = {
+            'wanted' => $wanted,
+            'no_chdir' => 1,
+        };
+        File::Find::find($opt, $input);
+        return @result;
+    }
+
+    return ($input);
+}
+
+=item program_name_to_perl_paths(PROGNAME)
+
+Map the program name (e.g. C<$0>) to a list of directories or/and
+files that should be processed.
+
+This helper sub is mostly useful for splitting up slow tests run over
+all Perl scripts/modules in Lintian.  This allows better use of
+multiple cores.  Example:
+
+
+  t/scripts/my-test/
+   runner.pl
+   checks.t -> runner.pl
+   collection.t -> runner.pl
+   ...
+
+And then in runner.pl:
+
+  use Test::Lintian;
+  
+  my @paths = program_name_to_perl_paths($0);
+  # test all files/dirs listed in @paths
+
+For a more concrete example, see t/scripts/01-critic/ and the
+files/symlinks beneath it.
+
+=cut
+
+{
+
+    my %SPECIAL_PATHS = (
+        'docs-examples' => ['doc/examples/checks'],
+        'test-scripts' => [qw(t/scripts t/templates)],
+    );
+
+    sub program_name_to_perl_paths {
+        my ($program) = @_;
+        # We need the basename before resolving the path (because
+        # afterwards it is "runner.pl" and we want it to be e.g.
+        # "checks.t" or "collections.t").
+        my $basename = basename($program, '.t');
+
+        if (exists($SPECIAL_PATHS{$basename})) {
+            return @{$SPECIAL_PATHS{$basename}};
+        }
+
+        return ($basename);
+    }
+}
+
+=back
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Test/Lintian/Build.pm b/lib/Test/Lintian/Build.pm
new file mode 100644
index 0000000..b6819af
--- /dev/null
+++ b/lib/Test/Lintian/Build.pm
@@ -0,0 +1,163 @@
+# Copyright (C) 2018 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA
+
+package Test::Lintian::Build;
+
+=head1 NAME
+
+Test::Lintian::Build -- routines to prepare the work directories
+
+=head1 SYNOPSIS
+
+  use Test::Lintian::Build qw(build_subject);
+
+=head1 DESCRIPTION
+
+The routines in this module prepare the work directories in which the
+tests are run. To do so, they use the specifications in the test set.
+
+=cut
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+BEGIN {
+    our @EXPORT_OK = qw(
+      build_subject
+    );
+}
+
+use Carp;
+use Const::Fast;
+use Cwd;
+use IPC::Run3;
+use List::SomeUtils qw(any);
+use Path::Tiny;
+use Unicode::UTF8 qw(valid_utf8 encode_utf8);
+
+use Lintian::Util qw(utf8_clean_log);
+
+use Test::Lintian::ConfigFile qw(read_config);
+use Test::Lintian::Hooks qw(find_missing_prerequisites);
+
+const my $SLASH => q{/};
+const my $WAIT_STATUS_SHIFT => 8;
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item build_subject(PATH)
+
+Populates a work directory RUN_PATH with data from the test located
+in SPEC_PATH. The optional parameter REBUILD forces a rebuild if true.
+
+=cut
+
+sub build_subject {
+    my ($sourcepath, $buildpath) = @_;
+
+    # check test architectures
+    die encode_utf8('DEB_HOST_ARCH is not set.')
+      unless (length $ENV{'DEB_HOST_ARCH'});
+
+    # read dynamic file names
+    my $runfiles = "$sourcepath/files";
+    my $files = read_config($runfiles);
+
+    # read dynamic case data
+    my $rundescpath
+      = $sourcepath . $SLASH . $files->unfolded_value('Fill-Values');
+    my $testcase = read_config($rundescpath);
+
+    # skip test if marked
+    my $skipfile = "$sourcepath/skip";
+    if (-e $skipfile) {
+        my $reason = path($skipfile)->slurp_utf8 || 'No reason given';
+        say encode_utf8("Skipping test: $reason");
+        return;
+    }
+
+    # skip if missing prerequisites
+    my $missing = find_missing_prerequisites($testcase);
+    if (length $missing) {
+        say encode_utf8("Missing prerequisites: $missing");
+        return;
+    }
+
+    path($buildpath)->remove_tree
+      if -e $buildpath;
+
+    path($buildpath)->mkpath;
+
+    # get lintian subject
+    croak encode_utf8('Could not get subject of Lintian examination.')
+      unless $testcase->declares('Build-Product');
+
+    my $build_product = $testcase->unfolded_value('Build-Product');
+    my $subject = "$buildpath/$build_product";
+
+    say encode_utf8("Building in $buildpath");
+
+    my $command = $testcase->unfolded_value('Build-Command');
+    if (length $command) {
+
+        my $savedir = Cwd::getcwd;
+        chdir($buildpath)
+          or die encode_utf8("Cannot change to directory $buildpath");
+
+        my $combined_bytes;
+
+        # array command breaks test files/contents/contains-build-path
+        run3($command, \undef, \$combined_bytes, \$combined_bytes);
+        my $status = ($? >> $WAIT_STATUS_SHIFT);
+
+        chdir($savedir)
+          or die encode_utf8("Cannot change to directory $savedir");
+
+        # sanitize log so it is UTF-8 from here on
+        my $utf8_bytes = utf8_clean_log($combined_bytes);
+        print $utf8_bytes;
+
+        croak encode_utf8("$command failed")
+          if $status;
+    }
+
+    croak encode_utf8('Build was unsuccessful.')
+      unless -e $subject;
+
+    die encode_utf8("Cannot link to build product $build_product")
+      if system("cd $buildpath; ln -s $build_product subject");
+
+    return;
+}
+
+=back
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Test/Lintian/ConfigFile.pm b/lib/Test/Lintian/ConfigFile.pm
new file mode 100644
index 0000000..162b49c
--- /dev/null
+++ b/lib/Test/Lintian/ConfigFile.pm
@@ -0,0 +1,132 @@
+# Copyright (C) 2018 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA
+
+package Test::Lintian::ConfigFile;
+
+=head1 NAME
+
+Test::Lintian::ConfigFile -- generic helper routines for colon-delimited configuration files
+
+=head1 SYNOPSIS
+
+use Test::Lintian::ConfigFile qw(read_config);
+my $desc = read_config('t/tags/testname/desc');
+
+=head1 DESCRIPTION
+
+Routines for dealing with colon-delimited configuration files.
+
+=cut
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+BEGIN {
+    our @EXPORT_OK = qw(
+      read_config
+      write_config
+    );
+}
+
+use Carp;
+use Const::Fast;
+use List::SomeUtils qw(any);
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Deb822;
+
+const my $SPACE => q{ };
+const my $COLON => q{:};
+const my $NEWLINE => qq{\n};
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item read_config(PATH, HASHREF)
+
+Reads the configuration file located at PATH into a hash and
+returns it. When also passed a HASHREF, will fill that instead.
+
+=cut
+
+sub read_config {
+    my ($configpath) = @_;
+
+    croak encode_utf8("Cannot find file $configpath.")
+      unless -e $configpath;
+
+    my $deb822 = Lintian::Deb822->new;
+    my @sections = $deb822->read_file($configpath);
+    die encode_utf8("$configpath does not have exactly one paragraph")
+      unless @sections == 1;
+
+    my $config = $sections[0];
+
+    return $config;
+}
+
+=item write_config(TEST_CASE, PATH)
+
+Write the config described by hash reference TEST_CASE to the file named PATH.
+
+=cut
+
+sub write_config {
+    my ($testcase, $path) = @_;
+
+    my $desc = path($path);
+    $desc->remove;
+
+    my @lines;
+    for my $name (sort $testcase->names) {
+
+        my @elements = $testcase->trimmed_list($name);
+
+        # multi-line output for some fields
+        if (@elements > 1
+            && any { fc eq fc($name) } qw(Test-For Test-Against)) {
+            push(@lines, $name . $COLON . $NEWLINE);
+            push(@lines, $SPACE . $_ . $NEWLINE) for @elements;
+            next;
+        }
+
+        push(@lines,
+            $name . $COLON . $SPACE . $testcase->value($name) . $NEWLINE);
+    }
+
+    $desc->append_utf8(@lines);
+
+    return;
+}
+
+=back
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Test/Lintian/Filter.pm b/lib/Test/Lintian/Filter.pm
new file mode 100644
index 0000000..4b6ea8a
--- /dev/null
+++ b/lib/Test/Lintian/Filter.pm
@@ -0,0 +1,378 @@
+# Copyright (C) 2020 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA.
+
+package Test::Lintian::Filter;
+
+=head1 NAME
+
+Test::Lintian::Filter -- Functions to select with tests to run
+
+=head1 SYNOPSIS
+
+  use Test::Lintian::Filter qw(find_selected_lintian_testpaths);
+  my @testpaths = find_selected_lintian_testpaths('suite:changes');
+
+=head1 DESCRIPTION
+
+Functions that parse the optional argument 'only_run' to find the
+tests that are supposed to run.
+
+=cut
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+BEGIN {
+    our @EXPORT_OK = qw(
+      find_selected_scripts
+      find_selected_lintian_testpaths
+    );
+}
+
+use Carp;
+use Const::Fast;
+use File::Spec::Functions qw(rel2abs splitpath catpath);
+use File::Find::Rule;
+use List::SomeUtils qw(uniq none);
+use List::Util qw(any all);
+use Path::Tiny;
+use Text::CSV;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Profile;
+use Test::Lintian::ConfigFile qw(read_config);
+
+my @LINTIAN_SUITES = qw(recipes);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $VERTICAL_BAR => q{|};
+const my $DESC => 'desc';
+const my $SEPARATED_BY_COLON => qr/([^:]+):([^:]+)/;
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item get_suitepath(TEST_SET, SUITE)
+
+Returns a string containing all test belonging to suite SUITE relative
+to path TEST_SET.
+
+=cut
+
+sub get_suitepath {
+    my ($basepath, $suite) = @_;
+    my $suitepath = rel2abs($suite, $basepath);
+
+    croak encode_utf8("Cannot find suite $suite in $basepath")
+      unless -d $suitepath;
+
+    return $suitepath;
+}
+
+=item find_selected_scripts(SCRIPT_PATH, ONLY_RUN)
+
+Find all test scripts in SCRIPT_PATH that are identified by the
+user's selection string ONLY_RUN.
+
+=cut
+
+sub find_selected_scripts {
+    my ($scriptpath, $onlyrun) = @_;
+
+    my @found;
+
+    my @selectors = split(m/\s*,\s*/, $onlyrun//$EMPTY);
+
+    if ((any { $_ eq 'suite:scripts' } @selectors) || !length $onlyrun) {
+        @found = File::Find::Rule->file()->name('*.t')->in($scriptpath);
+    } else {
+        foreach my $selector (@selectors) {
+            my ($prefix, $lookfor) = ($selector =~ /$SEPARATED_BY_COLON/);
+
+            next if defined $prefix && $prefix ne 'script';
+            $lookfor = $selector unless defined $prefix;
+
+            # look for files with the standard suffix
+            my $withsuffix = rel2abs("$lookfor.t", $scriptpath);
+            push(@found, $withsuffix) if -e $withsuffix;
+
+            # look for script with exact name
+            my $exactpath = rel2abs($lookfor, $scriptpath);
+            push(@found, $exactpath) if -e $exactpath;
+
+            # also add entire directory if name matches
+            push(@found, File::Find::Rule->file()->name('*.t')->in($exactpath))
+              if -d $exactpath;
+        }
+    }
+
+    my @sorted = sort +uniq @found;
+
+    return @sorted;
+}
+
+=item find_selected_lintian_testpaths(TEST_SET, ONLY_RUN)
+
+Find all those test paths with Lintian tests located in the directory
+TEST_SET and identified by the user's selection string ONLY_RUN.
+
+=cut
+
+sub find_selected_lintian_testpaths {
+
+    my ($testset, $onlyrun) = @_;
+
+    my $filter = {
+        'tag' => [],
+        'suite' => [],
+        'test' => [],
+        'check' => [],
+        'skeleton' => [],
+    };
+    my @filter_no_prefix;
+
+    if (!length $onlyrun) {
+        $filter->{suite} = [@LINTIAN_SUITES];
+    } else {
+
+        my @selectors = split(m/\s*,\s*/, $onlyrun);
+
+        foreach my $selector (@selectors) {
+
+            foreach my $wanted (keys %{$filter}) {
+                my ($prefix, $lookfor) = ($selector =~ /$SEPARATED_BY_COLON/);
+
+                next if defined $prefix && $prefix ne $wanted;
+
+                push(@{$filter->{$wanted}}, $lookfor) if length $lookfor;
+                push(@filter_no_prefix, $selector) unless length $lookfor;
+            }
+        }
+    }
+
+    my $profile = Lintian::Profile->new;
+    $profile->load(undef, undef, 0);
+
+    my @found;
+    foreach my $suite (sort @LINTIAN_SUITES) {
+
+        my @insuite;
+        my $suitepath = get_suitepath($testset, $suite);
+
+        # find all tests for selected suites
+        if (any { $_ eq $suite } @{$filter->{suite}}) {
+            push(@insuite, find_all_testpaths($suitepath));
+        }
+
+        # find explicitly selected tests
+        foreach my $testname (@{$filter->{test}}) {
+            my @withtests = find_testpaths_by_name($suitepath, $testname);
+            push(@insuite, @withtests);
+        }
+
+        # find tests for selected checks and tags
+        if (scalar @{$filter->{check}} || scalar @{$filter->{tag}}) {
+
+            my %wanted = map { $_ => 1 } @{$filter->{check}};
+
+            for my $tag_name (@{$filter->{tag}}) {
+
+                my $tag = $profile->get_tag($tag_name);
+                unless ($tag) {
+                    say encode_utf8("Tag $tag_name not found");
+                    return ();
+                }
+
+                if (none { $tag_name eq $_ } $profile->enabled_tags) {
+                    say encode_utf8("Tag $tag_name not enabled");
+                    return ();
+                }
+
+                $wanted{$tag->check} = 1;
+            }
+
+            for my $testpath (find_all_testpaths($suitepath)) {
+                my $desc = read_config("$testpath/eval/" . $DESC);
+
+                next
+                  unless $desc->declares('Check');
+
+                for my $check ($desc->trimmed_list('Check')) {
+                    push(@insuite, $testpath)
+                      if exists $wanted{$check};
+                }
+            }
+        }
+
+        # find tests for selected skeleton
+        if (scalar @{$filter->{skeleton}}) {
+
+            my %wanted = map { $_ => 1 } @{$filter->{skeleton}};
+
+            for my $testpath (find_all_testpaths($suitepath)) {
+                my $desc = read_config("$testpath/build-spec/fill-values");
+
+                next
+                  unless $desc->declares('Skeleton');
+
+                my $skeleton = $desc->unfolded_value('Skeleton');
+                push(@insuite, $testpath)
+                  if exists $wanted{$skeleton};
+            }
+        }
+
+        # guess what was meant by selection without prefix
+        for my $parameter (@filter_no_prefix) {
+            push(@insuite,find_testpaths_by_name($suitepath, $parameter));
+
+            if ($parameter eq 'legacy'
+                || exists $profile->check_module_by_name->{$parameter}) {
+
+                push(@insuite,
+                    find_testpaths_by_name($suitepath, "$parameter-*"));
+            }
+        }
+
+        push(@found, sort +uniq @insuite);
+    }
+
+    return @found;
+}
+
+=item find_all_testpaths(PATH)
+
+Returns an array containing all test paths located under PATH. They
+are identified as test paths by a specially named file containing
+the test description (presently 'desc').
+
+=cut
+
+sub find_all_testpaths {
+    my ($directory) = @_;
+    my @descfiles = File::Find::Rule->file()->name($DESC)->in($directory);
+
+    my @testpaths= map { path($_)->parent->parent->stringify }@descfiles;
+
+    return @testpaths;
+}
+
+=item find_testpaths_by_name(PATH, NAME)
+
+Returns an array containing all test paths with the name NAME
+located under PATH. The test paths are identified as such
+by a specially named file containing the test description
+(presently 'desc').
+
+=cut
+
+sub find_testpaths_by_name {
+    my ($path, $name) = @_;
+
+    my @named = File::Find::Rule->directory()->name($name)->in($path);
+    my @testpaths= grep { defined }
+      map { -e rel2abs('eval/' . $DESC, $_) ? $_ : undef } @named;
+
+    return @testpaths;
+}
+
+=item find_all_tags(TEST_PATH)
+
+Returns an array containing all tags that somehow concern the test
+located in TEST_PATH.
+
+=cut
+
+sub find_all_tags {
+    my ($testpath) = @_;
+
+    my $desc = read_config("$testpath/eval/" . $DESC);
+
+    return $EMPTY
+      unless $desc->declares('Check');
+
+    my $profile = Lintian::Profile->new;
+    $profile->load(undef, undef, 0);
+
+    my @check_names = $desc->trimmed_list('Check');
+    my @unknown
+      = grep { !exists $profile->check_module_by_name->{$_} } @check_names;
+
+    die encode_utf8('Unknown Lintian checks: ' . join($SPACE, @unknown))
+      if @unknown;
+
+    my %tags;
+    for my $name (@check_names) {
+        $tags{$_} = 1 for @{$profile->tag_names_for_check->{$name}};
+    }
+
+    return keys %tags
+      unless $desc->declares('Test-Against');
+
+    # read hints from specification
+    my $temp = Path::Tiny->tempfile;
+    die encode_utf8("hintextract failed: $!")
+      if system('private/hintextract', '-f', 'EWI', "$testpath/hints",
+        $temp->stringify);
+    my @lines = $temp->lines_utf8({ chomp => 1 });
+
+    my $csv = Text::CSV->new({ sep_char => $VERTICAL_BAR });
+
+    my %expected;
+    foreach my $line (@lines) {
+
+        my $status = $csv->parse($line);
+        die encode_utf8("Cannot parse line $line: " . $csv->error_diag)
+          unless $status;
+
+        my ($type, $package, $name, $details) = $csv->fields;
+
+        die encode_utf8("Cannot parse line $line")
+          unless all { length } ($type, $package, $name);
+
+        $expected{$name} = 1;
+    }
+
+    # remove tags not appearing in specification
+    foreach my $name (keys %tags) {
+        delete $tags{$name}
+          unless $expected{$name};
+    }
+
+    # add tags listed in Test-Against
+    my @test_against = $desc->trimmed_list('Test-Against');
+    $tags{$_} = 1 for @test_against;
+
+    return keys %tags;
+}
+
+=back
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Test/Lintian/Helper.pm b/lib/Test/Lintian/Helper.pm
new file mode 100644
index 0000000..518d036
--- /dev/null
+++ b/lib/Test/Lintian/Helper.pm
@@ -0,0 +1,198 @@
+# Copyright (C) 1998 Richard Braakman
+# Copyright (C) 2008 Frank Lichtenheld
+# Copyright (C) 2008, 2009 Russ Allbery
+# Copyright (C) 2018 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA
+
+package Test::Lintian::Helper;
+
+=head1 NAME
+
+Test::Lintian::Helper -- Helper functions for various testing parts
+
+=head1 SYNOPSIS
+
+  use Test::Lintian::Helper qw(get_latest_policy);
+  my $policy_version = get_latest_policy();
+
+=head1 DESCRIPTION
+
+Helper functions for preparing and running Lintian tests.
+
+=cut
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+BEGIN {
+    our @EXPORT_OK = qw(
+      cache_dpkg_architecture_values
+      get_latest_policy
+      get_recommended_debhelper_version
+      copy_dir_contents
+      rfc822date
+    );
+}
+
+use Carp;
+use File::Spec::Functions qw(abs2rel rel2abs);
+use File::Path qw(remove_tree);
+use Path::Tiny;
+use POSIX qw(locale_h strftime);
+use Unicode::UTF8 qw(encode_utf8 decode_utf8);
+
+use Lintian::IPC::Run3 qw(safe_qx);
+use Lintian::Profile;
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item cache_dpkg_architecture_values()
+
+Ensures that the output from dpkg-architecture has been cached.
+
+=cut
+
+sub cache_dpkg_architecture_values {
+
+    my $output = decode_utf8(safe_qx('dpkg-architecture'));
+
+    die encode_utf8('dpkg-architecture failed')
+      if $?;
+
+    $output = decode_utf8($output)
+      if length $output;
+
+    my @lines = split(/\n/, $output);
+
+    for my $line (@lines) {
+        my ($k, $v) = split(/=/, $line, 2);
+        $ENV{$k} = $v;
+    }
+
+    return;
+}
+
+=item get_latest_policy()
+
+Returns a list with two elements. The first is the most recent version
+of the Debian policy. The second is its effective date.
+
+=cut
+
+sub get_latest_policy {
+    my $profile = Lintian::Profile->new;
+    $profile->load(undef, undef, 0);
+
+    my $releases = $profile->data->policy_releases;
+
+    my $version = $releases->latest_version;
+    die encode_utf8('Could not get latest policy version.')
+      unless defined $version;
+    my $epoch = $releases->epoch($version);
+    die encode_utf8('Could not get latest policy date.')
+      unless defined $epoch;
+
+    return ($version, $epoch);
+}
+
+=item get_recommended_debhelper_version()
+
+Returns the version of debhelper recommended in 'debhelper/compat-level'
+via Lintian::Data, relative to the established LINTIAN_BASE.
+
+=cut
+
+sub get_recommended_debhelper_version {
+    my $profile = Lintian::Profile->new;
+    $profile->load(undef, undef, 0);
+
+    my $compat_level = $profile->data->debhelper_levels;
+
+    return $compat_level->value('recommended');
+}
+
+=item copy_dir_contents(SRC_DIR, TARGET_DIR)
+
+Populates TARGET_DIR with files/dirs from SRC_DIR, preserving all attributes but
+dereferencing links. For an empty directory, no dummy file is required.
+
+=cut
+
+sub copy_dir_contents {
+    my ($source, $destination) = @_;
+
+    # 'cp -r' cannot overwrite directories with files or vice versa
+    my @paths = File::Find::Rule->in($source);
+    foreach my $path (@paths) {
+
+        my $relative = abs2rel($path, $source);
+        my $prospective = rel2abs($relative, $destination);
+
+        # recursively delete directories to be replaced by a file
+        remove_tree($prospective)
+          if -d $prospective && -e $path && !-d _;
+
+        # remove files to be replaced by a directory
+        if (-e $prospective && !-d _ && -d $path) {
+            unlink($prospective)
+              or die encode_utf8("Cannot unlink $prospective");
+        }
+    }
+
+    # 'cp -r' with a dot will error without files present
+    if (scalar path($source)->children) {
+
+        system('cp', '-rp', "$source/.", '-t', $destination)== 0
+          or croak encode_utf8("Could not copy $source to $destination: $!");
+    }
+    return 1;
+}
+
+=item rfc822date(EPOCH)
+
+Returns a string with the date and time described by EPOCH, formatted
+according to RFC822.
+
+=cut
+
+sub rfc822date {
+    my ($epoch) = @_;
+
+    my $old_locale = setlocale(LC_TIME, 'C');
+    my $datestring = strftime('%a, %d %b %Y %H:%M:%S %z', localtime($epoch));
+    setlocale(LC_TIME, $old_locale);
+
+    return $datestring;
+}
+
+=back
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Test/Lintian/Hooks.pm b/lib/Test/Lintian/Hooks.pm
new file mode 100644
index 0000000..4c8d848
--- /dev/null
+++ b/lib/Test/Lintian/Hooks.pm
@@ -0,0 +1,228 @@
+# Copyright (C) 2018 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA
+
+package Test::Lintian::Hooks;
+
+=head1 NAME
+
+Test::Lintian::Hooks -- hook routines for the test runners
+
+=head1 SYNOPSIS
+
+  use Test::Lintian::Hooks qw(sed_hook);
+  sed_hook('script.sed', 'input.file');
+
+=head1 DESCRIPTION
+
+Various hook routines for the test runners.
+
+=cut
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+BEGIN {
+    our @EXPORT_OK = qw(
+      sed_hook
+      sort_lines
+      calibrate
+      find_missing_prerequisites
+    );
+}
+
+use Capture::Tiny qw(capture_merged);
+use Carp;
+use Const::Fast;
+use Cwd qw(getcwd);
+use File::Basename;
+use File::Find::Rule;
+use File::Path;
+use File::stat;
+use IPC::Run3;
+use List::SomeUtils qw(any);
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8 decode_utf8);
+
+const my $NEWLINE => qq{\n};
+const my $WAIT_STATUS_SHIFT => 8;
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item sed_hook(SCRIPT, SUBJECT, OUTPUT)
+
+Runs the parser sed on file SUBJECT using the instructions in SCRIPT
+and places the result in the file OUTPUT.
+
+=cut
+
+sub sed_hook {
+    my ($script, $path, $output) = @_;
+
+    croak encode_utf8("Parser script $script does not exist.")
+      unless -e $script;
+
+    my @command = (qw{sed -r -f}, $script, $path);
+    my $bytes;
+    run3(\@command, \undef, \$bytes);
+    my $status = ($? >> $WAIT_STATUS_SHIFT);
+
+    croak encode_utf8("Hook failed: sed -ri -f $script $path > $output: $!")
+      if $status;
+
+    # already in bytes
+    path($output)->spew($bytes);
+
+    croak encode_utf8("Did not create parser output file $output.")
+      unless -e $output;
+
+    return $output;
+}
+
+=item sort_lines(UNSORTED, SORTED)
+
+Sorts the file UNSORTED line by line and places the result into the
+file SORTED.
+
+=cut
+
+sub sort_lines {
+    my ($path, $sorted) = @_;
+
+    open(my $rfd, '<', $path)
+      or croak encode_utf8("Could not open pre-sort file $path: $!");
+    my @lines = sort map { decode_utf8($_) } <$rfd>;
+    close $rfd
+      or carp encode_utf8("Could not close open pre-sort file $path: $!");
+
+    open(my $wfd, '>', $sorted)
+      or croak encode_utf8("Could not open sorted file $sorted: $!");
+    print {$wfd} encode_utf8($_) for @lines;
+    close $wfd
+      or carp encode_utf8("Could not close sorted file $sorted: $!");
+
+    return $sorted;
+}
+
+=item calibrate(SCRIPT, ACTUAL, EXPECTED, CALIBRATED)
+
+Executes calibration script SCRIPT with the three arguments EXPECTED,
+ACTUAL and CALIBRATED, all of which are file paths. Please note that
+the order of arguments in this function corresponds to the
+bookkeeping logic of ACTUAL vs EXPECTED. The order for the script is
+different.
+
+=cut
+
+sub calibrate {
+    my ($hook, $actual, $expected, $calibrated) = @_;
+
+    if (-x $hook) {
+        system($hook, $expected, $actual, $calibrated) == 0
+          or croak encode_utf8("Hook $hook failed on $actual: $!");
+        croak encode_utf8("No calibrated hints created in $calibrated")
+          unless -e $calibrated;
+        return $calibrated;
+    }
+    return $expected;
+}
+
+=item find_missing_prerequisites(TEST_CASE)
+
+Returns a string with missing dependencies, if applicable, that would
+be necessary to run the test described by hash DESC.
+
+=cut
+
+sub find_missing_prerequisites {
+    my ($testcase) = @_;
+
+    # without prerequisites, no need to look
+    return undef
+      unless any { $testcase->declares($_) }
+      qw(Build-Depends Build-Conflicts Test-Depends Test-Conflicts);
+
+    # create a temporary file
+    my $temp = Path::Tiny->tempfile(
+        TEMPLATE => 'lintian-test-build-depends-XXXXXXXXX');
+    my @lines;
+
+    # dpkg-checkbuilddeps requires a Source: field
+    push(@lines, 'Source: bd-test-pkg');
+
+    my $build_depends = join(
+        ', ',
+        grep { length }(
+            $testcase->value('Build-Depends'),$testcase->value('Test-Depends')
+        )
+    );
+
+    push(@lines, "Build-Depends: $build_depends")
+      if length $build_depends;
+
+    my $build_conflicts = join(
+        ', ',
+        grep { length }(
+            $testcase->value('Build-Conflicts'),
+            $testcase->value('Test-Conflicts')
+        )
+    );
+    push(@lines, "Build-Conflicts: $build_conflicts")
+      if length $build_conflicts;
+
+    $temp->spew_utf8(join($NEWLINE, @lines) . $NEWLINE);
+
+    # run dpkg-checkbuilddeps
+    my $command = "dpkg-checkbuilddeps $temp";
+    my ($missing, $status) = capture_merged { system($command); };
+    $status >>= $WAIT_STATUS_SHIFT;
+
+    $missing = decode_utf8($missing)
+      if length $missing;
+
+    die encode_utf8("$command failed: $missing")
+      if !$status && length $missing;
+
+    # parse for missing prerequisites
+    if ($missing =~ s{\A dpkg-checkbuilddeps: [ ] (?:error: [ ])? }{}xsm) {
+        $missing =~ s{Unmet build dependencies}{Unmet}gi;
+        chomp($missing);
+        # expect exactly one line.
+        die encode_utf8("Unexpected output from dpkg-checkbuilddeps: $missing")
+          if $missing =~ s{\n}{\\n}gxsm;
+        return $missing;
+    }
+
+    return undef;
+}
+
+=back
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Test/Lintian/Output/EWI.pm b/lib/Test/Lintian/Output/EWI.pm
new file mode 100644
index 0000000..74fab49
--- /dev/null
+++ b/lib/Test/Lintian/Output/EWI.pm
@@ -0,0 +1,117 @@
+# Copyright (C) 2019 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA
+
+package Test::Lintian::Output::EWI;
+
+=head1 NAME
+
+Test::Lintian::Output::EWI -- routines to process EWI hints
+
+=head1 SYNOPSIS
+
+  use Path::Tiny;
+  use Test::Lintian::Output::EWI qw(to_universal);
+
+  my $ewi = path("path to an EWI hint file")->slurp_utf8;
+  my $universal = to_universal($ewi);
+
+=head1 DESCRIPTION
+
+Helper routines to deal with C<EWI> hints and hint files
+
+=cut
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+BEGIN {
+    our @EXPORT_OK = qw(
+      to_universal
+    );
+}
+
+use Carp;
+use Const::Fast;
+use List::Util qw(all);
+use Unicode::UTF8 qw(encode_utf8);
+
+use Test::Lintian::Output::Universal qw(universal_string order);
+
+const my $EMPTY   => q{};
+const my $NEWLINE => qq{\n};
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item to_universal(STRING)
+
+Converts the C<EWI> hint data contained in STRING to universal hints.
+They are likewise delivered in a multi-line string.
+
+=cut
+
+sub to_universal {
+    my ($ewi) = @_;
+
+    my @unsorted;
+
+    my @lines = split($NEWLINE, $ewi);
+    chomp @lines;
+
+    foreach my $line (@lines) {
+
+        # no hint in this line
+        next if $line =~ /^N: /;
+
+        # look for "EWI: package[ type]: name details"
+        my ($code, $package, $type, $name, $details)
+          = $line=~ /^(.): (\S+)(?: (changes|source|udeb))?: (\S+)(?: (.*))?$/;
+
+        # for binary packages, the type field is empty
+        $type //= 'binary';
+
+        croak encode_utf8("Cannot parse line $line")
+          unless all { length } ($code, $package, $type, $name);
+
+        my $converted = universal_string($package, $type, $name, $details);
+        push(@unsorted, $converted);
+    }
+
+    my @sorted = reverse sort { order($a) cmp order($b) } @unsorted;
+
+    my $universal = $EMPTY;
+    $universal .= $_ . $NEWLINE for @sorted;
+
+    return $universal;
+}
+
+=back
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Test/Lintian/Output/Universal.pm b/lib/Test/Lintian/Output/Universal.pm
new file mode 100644
index 0000000..707b958
--- /dev/null
+++ b/lib/Test/Lintian/Output/Universal.pm
@@ -0,0 +1,189 @@
+# Copyright (C) 2019 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA
+
+package Test::Lintian::Output::Universal;
+
+=head1 NAME
+
+Test::Lintian::Output::Universal -- routines to process universal hints
+
+=head1 SYNOPSIS
+
+  use Test::Lintian::Output::Universal qw(get_tag_names);
+
+  my $filepath = "path to a universal hint file";
+  my @tags = get_tag_names($filepath);
+
+=head1 DESCRIPTION
+
+Helper routines to deal with universal hints and hint files. This is an
+abstract format that has the minimum information found in all Lintian
+output formats.
+
+=cut
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+BEGIN {
+    our @EXPORT_OK = qw(
+      get_tag_names
+      order
+      package_name
+      package_type
+      tag_name
+      parse_line
+      universal_string
+    );
+}
+
+use Carp;
+use Const::Fast;
+use List::SomeUtils qw(uniq);
+use List::Util qw(all);
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+
+const my $SPACE => q{ };
+const my $COLON => q{:};
+const my $LPARENS => q{(};
+const my $RPARENS => q{)};
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item get_tag_names(PATH)
+
+Gets all the tag names mentioned in universal hint file located
+at PATH.
+
+=cut
+
+sub get_tag_names {
+    my ($path) = @_;
+
+    my @lines = path($path)->lines_utf8({ chomp => 1 });
+    my @names = map { tag_name($_) } @lines;
+
+    return uniq @names;
+}
+
+=item order
+
+=cut
+
+sub order {
+    my ($line) = @_;
+
+    return package_type($line) . $line;
+}
+
+=item package_name
+
+=cut
+
+sub package_name {
+    my ($line) = @_;
+
+    my ($package, undef, undef, undef) = parse_line($line);
+    return $package;
+}
+
+=item package_type
+
+=cut
+
+sub package_type {
+    my ($line) = @_;
+
+    my (undef, $type, undef, undef) = parse_line($line);
+    return $type;
+}
+
+=item tag_name
+
+=cut
+
+sub tag_name {
+    my ($line) = @_;
+
+    my (undef, undef, $name, undef) = parse_line($line);
+    return $name;
+}
+
+=item parse_line
+
+=cut
+
+sub parse_line {
+    my ($line) = @_;
+
+    my ($package, $type, $name, $details)
+      = $line =~ qr/^(\S+)\s+\(([^)]+)\):\s+(\S+)(?:\s+(.*))?$/;
+
+    croak encode_utf8("Cannot parse line $line")
+      unless all { length } ($package, $type, $name);
+
+    return ($package, $type, $name, $details);
+}
+
+=item universal_string
+
+=cut
+
+sub universal_string {
+    my ($package, $type, $name, $details) = @_;
+
+    croak encode_utf8('Need a package name')
+      unless length $package;
+    croak encode_utf8('Need a package type')
+      unless length $type;
+    croak encode_utf8('Need a tag name')
+      unless length $name;
+
+    my $line
+      = $package. $SPACE. $LPARENS. $type. $RPARENS. $COLON. $SPACE. $name;
+    $line .= $SPACE . $details
+      if length $details;
+
+    return $line;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Test/Lintian/Prepare.pm b/lib/Test/Lintian/Prepare.pm
new file mode 100644
index 0000000..8914fcc
--- /dev/null
+++ b/lib/Test/Lintian/Prepare.pm
@@ -0,0 +1,551 @@
+# Copyright (C) 2018-2020 Felix Lechner
+# Copyright (C) 2019 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA
+
+package Test::Lintian::Prepare;
+
+=head1 NAME
+
+Test::Lintian::Prepare -- routines to prepare the work directories
+
+=head1 SYNOPSIS
+
+  use Test::Lintian::Prepare qw(prepare);
+
+=head1 DESCRIPTION
+
+The routines in this module prepare the work directories in which the
+tests are run. To do so, they use the specifications in the test set.
+
+=cut
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+BEGIN {
+    our @EXPORT_OK = qw(
+      prepare
+      filleval
+    );
+}
+
+use Carp;
+use Const::Fast;
+use Cwd qw(getcwd);
+use File::Copy;
+use File::Find::Rule;
+use File::Path qw(make_path remove_tree);
+use File::stat;
+use List::Util qw(max);
+use Path::Tiny;
+use Text::Template;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Lintian::Deb822::Section;
+
+use Test::Lintian::ConfigFile qw(read_config write_config);
+use Test::Lintian::Helper qw(rfc822date copy_dir_contents);
+use Test::Lintian::Templates
+  qw(copy_skeleton_template_sets remove_surplus_templates fill_skeleton_templates);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $SLASH => q{/};
+const my $COMMA => q{,};
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item prepare(SPEC_PATH, SOURCE_PATH, TEST_SET, REBUILD)
+
+Populates a work directory SOURCE_PATH with data from the test located
+in SPEC_PATH. The optional parameter REBUILD forces a rebuild if true.
+
+=cut
+
+sub prepare {
+    my ($specpath, $sourcepath, $testset, $force_rebuild)= @_;
+
+    say encode_utf8('------- Preparation starts here -------');
+    say encode_utf8("Work directory is $sourcepath.");
+
+    # for template fill, earliest date without timewarp warning
+    my $data_epoch = $ENV{'POLICY_EPOCH'}//time;
+
+    # read defaults
+    my $defaultspath = "$testset/defaults";
+
+    # read default file names
+    my $defaultfilespath = "$defaultspath/files";
+    die encode_utf8("Cannot find $defaultfilespath")
+      unless -e $defaultfilespath;
+
+    # read file and adjust data age threshold
+    my $files = read_config($defaultfilespath);
+    #    $data_epoch= max($data_epoch, stat($defaultfilespath)->mtime);
+
+    # read test data
+    my $descpath = $specpath . $SLASH . $files->unfolded_value('Fill-Values');
+    my $desc = read_config($descpath);
+    #    $data_epoch= max($data_epoch, stat($descpath)->mtime);
+
+    # read test defaults
+    my $descdefaultspath
+      = $defaultspath . $SLASH . $files->unfolded_value('Fill-Values');
+    my $defaults = read_config($descdefaultspath);
+    #    $data_epoch= max($data_epoch, stat($descdefaultspath)->mtime);
+
+    # start with a shallow copy of defaults
+    my $testcase = Lintian::Deb822::Section->new;
+    $testcase->store($_, $defaults->value($_)) for $defaults->names;
+
+    die encode_utf8("Name missing for $specpath")
+      unless $desc->declares('Testname');
+
+    die encode_utf8('Outdated test specification (./debian/debian exists).')
+      if -e "$specpath/debian/debian";
+
+    if (-d $sourcepath) {
+
+        # check for old build artifacts
+        my $buildstamp = "$sourcepath/build-stamp";
+        say encode_utf8('Found old build artifact.') if -e $buildstamp;
+
+        # check for old debian/debian directory
+        my $olddebiandir = "$sourcepath/debian/debian";
+        say encode_utf8('Found old debian/debian directory.')
+          if -e $olddebiandir;
+
+        # check for rebuild demand
+        say encode_utf8('Forcing rebuild.') if $force_rebuild;
+
+        # delete work directory
+        if($force_rebuild || -e $buildstamp || -e $olddebiandir) {
+            say encode_utf8("Removing work directory $sourcepath.");
+            remove_tree($sourcepath);
+        }
+    }
+
+    # create work directory
+    unless (-d $sourcepath) {
+        say encode_utf8("Creating directory $sourcepath.");
+        make_path($sourcepath);
+    }
+
+    # delete old test scripts
+    my @oldrunners = File::Find::Rule->file->name('*.t')->in($sourcepath);
+    if (@oldrunners) {
+        unlink(@oldrunners)
+          or die encode_utf8("Cannot unlink @oldrunners");
+    }
+
+    my $skeletonname = $desc->unfolded_value('Skeleton');
+    if (length $skeletonname) {
+
+        # load skeleton
+        my $skeletonpath = "$testset/skeletons/$skeletonname";
+        my $skeleton = read_config($skeletonpath);
+
+        $testcase->store($_, $skeleton->value($_)) for $skeleton->names;
+    }
+
+    # populate working directory with specified template sets
+    copy_skeleton_template_sets($testcase->value('Template-Sets'),
+        $sourcepath, $testset)
+      if $testcase->declares('Template-Sets');
+
+    # delete templates for which we have originals
+    remove_surplus_templates($specpath, $sourcepath);
+
+    # copy test specification to working directory
+    my $offset = path($specpath)->relative($testset)->stringify;
+    say encode_utf8(
+        "Copy test specification $offset from $testset to $sourcepath.");
+    copy_dir_contents($specpath, $sourcepath);
+
+    my $valuefolder = $testcase->unfolded_value('Fill-Values-Folder');
+    if (length $valuefolder) {
+
+        # load all the values in the fill values folder
+        my $valuepath = "$sourcepath/$valuefolder";
+        my @filepaths
+          = File::Find::Rule->file->name('*.values')->in($valuepath);
+
+        for my $filepath (sort @filepaths) {
+            my $fill_values = read_config($filepath);
+
+            $testcase->store($_, $fill_values->value($_))
+              for $fill_values->names;
+        }
+    }
+
+    # add individual settings after skeleton
+    $testcase->store($_, $desc->value($_)) for $desc->names;
+
+    # record path to specification
+    $testcase->store('Spec-Path', $specpath);
+
+    # record path to specification
+    $testcase->store('Source-Path', $sourcepath);
+
+    # add other helpful info to testcase
+    $testcase->store('Source', $testcase->unfolded_value('Testname'))
+      unless $testcase->declares('Source');
+
+    # record our effective data age as date, unless given
+    $testcase->store('Date', rfc822date($data_epoch))
+      unless $testcase->declares('Date');
+
+    warn encode_utf8('Cannot override Architecture: in test '
+          . $testcase->unfolded_value('Testname'))
+      if $testcase->declares('Architecture');
+
+    die encode_utf8('DEB_HOST_ARCH is not set.')
+      unless defined $ENV{'DEB_HOST_ARCH'};
+    $testcase->store('Host-Architecture', $ENV{'DEB_HOST_ARCH'});
+
+    die encode_utf8('Could not get POLICY_VERSION.')
+      unless defined $ENV{'POLICY_VERSION'};
+    $testcase->store('Standards-Version', $ENV{'POLICY_VERSION'})
+      unless $testcase->declares('Standards-Version');
+
+    die encode_utf8('Could not get DEFAULT_DEBHELPER_COMPAT.')
+      unless defined $ENV{'DEFAULT_DEBHELPER_COMPAT'};
+    $testcase->store('Dh-Compat-Level', $ENV{'DEFAULT_DEBHELPER_COMPAT'})
+      unless $testcase->declares('Dh-Compat-Level');
+
+    # add additional version components
+    if ($testcase->declares('Version')) {
+
+        # add upstream version
+        my $upstream_version = $testcase->unfolded_value('Version');
+        $upstream_version =~ s/-[^-]+$//;
+        $upstream_version =~ s/(-|^)(\d+):/$1/;
+        $testcase->store('Upstream-Version', $upstream_version);
+
+        # version without epoch
+        my $no_epoch = $testcase->unfolded_value('Version');
+        $no_epoch =~ s/^\d+://;
+        $testcase->store('No-Epoch', $no_epoch);
+
+        unless ($testcase->declares('Prev-Version')) {
+            my $prev_version = '0.0.1';
+            $prev_version .= '-1'
+              unless $testcase->unfolded_value('Type') eq 'native';
+
+            $testcase->store('Prev-Version', $prev_version);
+        }
+    }
+
+    # calculate build dependencies
+    warn encode_utf8('Cannot override Build-Depends:')
+      if $testcase->declares('Build-Depends');
+    combine_fields($testcase, 'Build-Depends', $COMMA . $SPACE,
+        'Default-Build-Depends', 'Extra-Build-Depends');
+
+    # calculate build conflicts
+    warn encode_utf8('Cannot override Build-Conflicts:')
+      if $testcase->declares('Build-Conflicts');
+    combine_fields($testcase, 'Build-Conflicts', $COMMA . $SPACE,
+        'Default-Build-Conflicts', 'Extra-Build-Conflicts');
+
+    # fill testcase with itself; do it twice to make sure all is done
+    my $hashref = deb822_section_to_hash($testcase);
+    $hashref = fill_hash_from_hash($hashref);
+    $hashref = fill_hash_from_hash($hashref);
+    write_hash_to_deb822_section($hashref, $testcase);
+
+    say encode_utf8($EMPTY);
+
+    # fill remaining templates
+    fill_skeleton_templates($testcase->value('Fill-Targets'),
+        $hashref, $data_epoch, $sourcepath, $testset)
+      if $testcase->declares('Fill-Targets');
+
+    # write the dynamic file names
+    my $runfiles = path($sourcepath)->child('files');
+    write_config($files, $runfiles->stringify);
+
+    # set mtime for dynamic file names
+    $runfiles->touch($data_epoch);
+
+    # write the dynamic test case file
+    my $rundesc
+      = path($sourcepath)->child($files->unfolded_value('Fill-Values'));
+    write_config($testcase, $rundesc->stringify);
+
+    # set mtime for dynamic test data
+    $rundesc->touch($data_epoch);
+
+    say encode_utf8($EMPTY);
+
+    # announce data age
+    say encode_utf8('Data epoch is : '. rfc822date($data_epoch));
+
+    return;
+}
+
+=item filleval(SPEC_PATH, EVAL_PATH, TEST_SET, REBUILD)
+
+Populates a evaluation directory EVAL_PATH with data from the test located
+in SPEC_PATH. The optional parameter REBUILD forces a rebuild if true.
+
+=cut
+
+sub filleval {
+    my ($specpath, $evalpath, $testset, $force_rebuild)= @_;
+
+    say encode_utf8('------- Filling evaluation starts here -------');
+    say encode_utf8("Evaluation directory is $evalpath.");
+
+    # read defaults
+    my $defaultspath = "$testset/defaults";
+
+    # read default file names
+    my $defaultfilespath = "$defaultspath/files";
+    die encode_utf8("Cannot find $defaultfilespath")
+      unless -e $defaultfilespath;
+
+    # read file with default file names
+    my $files = read_config($defaultfilespath);
+
+    # read test data
+    my $descpath
+      = $specpath . $SLASH . $files->unfolded_value('Test-Specification');
+    my $desc = read_config($descpath);
+
+    # read test defaults
+    my $descdefaultspath
+      = $defaultspath . $SLASH . $files->unfolded_value('Test-Specification');
+    my $defaults = read_config($descdefaultspath);
+
+    # start with a shallow copy of defaults
+    my $testcase = Lintian::Deb822::Section->new;
+    $testcase->store($_, $defaults->value($_)) for $defaults->names;
+
+    die encode_utf8("Name missing for $specpath")
+      unless $desc->declares('Testname');
+
+    # delete old test scripts
+    my @oldrunners = File::Find::Rule->file->name('*.t')->in($evalpath);
+    if (@oldrunners) {
+        unlink(@oldrunners)
+          or die encode_utf8("Cannot unlink @oldrunners");
+    }
+
+    $testcase->store('Skeleton', $desc->value('Skeleton'))
+      unless $testcase->declares('Skeleton');
+
+    my $skeletonname = $testcase->unfolded_value('Skeleton');
+    if (length $skeletonname) {
+
+        # load skeleton
+        my $skeletonpath = "$testset/skeletons/$skeletonname";
+        my $skeleton = read_config($skeletonpath);
+
+        $testcase->store($_, $skeleton->value($_)) for $skeleton->names;
+    }
+
+    # add individual settings after skeleton
+    $testcase->store($_, $desc->value($_)) for $desc->names;
+
+    # populate working directory with specified template sets
+    copy_skeleton_template_sets($testcase->value('Template-Sets'),
+        $evalpath, $testset)
+      if $testcase->declares('Template-Sets');
+
+    # delete templates for which we have originals
+    remove_surplus_templates($specpath, $evalpath);
+
+    # copy test specification to working directory
+    my $offset = path($specpath)->relative($testset)->stringify;
+    say encode_utf8(
+        "Copy test specification $offset from $testset to $evalpath.");
+    copy_dir_contents($specpath, $evalpath);
+
+    my $valuefolder = $testcase->unfolded_value('Fill-Values-Folder');
+    if (length $valuefolder) {
+
+        # load all the values in the fill values folder
+        my $valuepath = "$evalpath/$valuefolder";
+        my @filepaths
+          = File::Find::Rule->file->name('*.values')->in($valuepath);
+
+        for my $filepath (sort @filepaths) {
+            my $fill_values = read_config($filepath);
+
+            $testcase->store($_, $fill_values->value($_))
+              for $fill_values->names;
+        }
+    }
+
+    # add individual settings after skeleton
+    $testcase->store($_, $desc->value($_)) for $desc->names;
+
+    # fill testcase with itself; do it twice to make sure all is done
+    my $hashref = deb822_section_to_hash($testcase);
+    $hashref = fill_hash_from_hash($hashref);
+    $hashref = fill_hash_from_hash($hashref);
+    write_hash_to_deb822_section($hashref, $testcase);
+
+    say encode_utf8($EMPTY);
+
+    # fill remaining templates
+    fill_skeleton_templates($testcase->value('Fill-Targets'),
+        $hashref, time, $evalpath, $testset)
+      if $testcase->declares('Fill-Targets');
+
+    # write the dynamic file names
+    my $runfiles = path($evalpath)->child('files');
+    write_config($files, $runfiles->stringify);
+
+    # write the dynamic test case file
+    my $rundesc
+      = path($evalpath)->child($files->unfolded_value('Test-Specification'));
+    write_config($testcase, $rundesc->stringify);
+
+    say encode_utf8($EMPTY);
+
+    return;
+}
+
+=item combine_fields
+
+=cut
+
+sub combine_fields {
+    my ($testcase, $destination, $delimiter, @sources) = @_;
+
+    return
+      unless length $destination;
+
+    # we are combining these contents
+    my @contents;
+    for my $source (@sources) {
+        push(@contents, $testcase->value($source))
+          if length $source;
+        $testcase->drop($source);
+    }
+
+    # combine
+    for my $content (@contents) {
+        $testcase->store(
+            $destination,
+            join($delimiter,
+                grep { length }($testcase->value($destination),$content))
+        );
+    }
+
+    # delete the combined entry if it is empty
+    $testcase->drop($destination)
+      unless length $testcase->value($destination);
+
+    return;
+}
+
+=item deb822_section_to_hash
+
+=cut
+
+sub deb822_section_to_hash {
+    my ($section) = @_;
+
+    my %hash;
+    for my $name ($section->names) {
+
+        my $transformed = lc $name;
+        $transformed =~ s/-/_/g;
+
+        $hash{$transformed} = $section->value($name);
+    }
+
+    return \%hash;
+}
+
+=item write_hash_to_deb822_section
+
+=cut
+
+sub write_hash_to_deb822_section {
+    my ($hashref, $section) = @_;
+
+    for my $name ($section->names) {
+
+        my $transformed = lc $name;
+        $transformed =~ s/-/_/g;
+
+        $section->store($name, $hashref->{$transformed});
+    }
+
+    return;
+}
+
+=item fill_hash_from_hash
+
+=cut
+
+sub fill_hash_from_hash {
+    my ($hashref, $delimiters) = @_;
+
+    $delimiters //= ['[%', '%]'];
+
+    my %origin = %{$hashref};
+    my %destination;
+
+    # fill hash with itself
+    for my $key (keys %origin) {
+
+        my $template = $origin{$key} // $EMPTY;
+        my $filler= Text::Template->new(TYPE => 'STRING', SOURCE => $template);
+        croak encode_utf8(
+            "Cannot read template $template: $Text::Template::ERROR")
+          unless $filler;
+
+        my $generated
+          = $filler->fill_in(HASH => \%origin, DELIMITERS => $delimiters);
+        croak encode_utf8("Could not create string from template $template")
+          unless defined $generated;
+        $destination{$key} = $generated;
+    }
+
+    return \%destination;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Test/Lintian/Run.pm b/lib/Test/Lintian/Run.pm
new file mode 100644
index 0000000..4fb7c97
--- /dev/null
+++ b/lib/Test/Lintian/Run.pm
@@ -0,0 +1,570 @@
+# Copyright (C) 2018 Felix Lechner
+# Copyright (C) 2019 Chris Lamb <lamby@debian.org>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA
+
+package Test::Lintian::Run;
+
+=head1 NAME
+
+Test::Lintian::Run -- generic runner for all suites
+
+=head1 SYNOPSIS
+
+  use Test::Lintian::Run qw(runner);
+
+  my $runpath = "test working directory";
+
+  runner($runpath);
+
+=head1 DESCRIPTION
+
+Generic test runner for all Lintian test suites
+
+=cut
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+BEGIN {
+    our @EXPORT_OK = qw(
+      logged_runner
+      runner
+      check_result
+    );
+}
+
+use Capture::Tiny qw(capture_merged);
+use Const::Fast;
+use Cwd qw(getcwd);
+use File::Basename qw(basename);
+use File::Spec::Functions qw(abs2rel rel2abs splitpath catpath);
+use File::Compare;
+use File::Copy;
+use File::stat;
+use IPC::Run3;
+use List::Compare;
+use List::Util qw(max min any all);
+use Path::Tiny;
+use Syntax::Keyword::Try;
+use Test::More;
+use Text::Diff;
+use Unicode::UTF8 qw(encode_utf8 decode_utf8);
+
+use Lintian::Deb822;
+use Lintian::Profile;
+
+use Test::Lintian::ConfigFile qw(read_config);
+use Test::Lintian::Helper qw(rfc822date);
+use Test::Lintian::Hooks
+  qw(find_missing_prerequisites sed_hook sort_lines calibrate);
+use Test::Lintian::Output::Universal qw(get_tag_names order);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $INDENT => $SPACE x 2;
+const my $SLASH => q{/};
+const my $NEWLINE => qq{\n};
+const my $YES => q{yes};
+const my $NO => q{no};
+
+const my $WAIT_STATUS_SHIFT => 8;
+
+# turn off the @@-style headers in Text::Diff
+no warnings 'redefine';
+sub Text::Diff::Unified::file_header { return $EMPTY; }
+sub Text::Diff::Unified::hunk_header { return $EMPTY; }
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item logged_runner(RUN_PATH)
+
+Starts the generic test runner for the test located in RUN_PATH
+and logs the output.
+
+=cut
+
+sub logged_runner {
+    my ($runpath) = @_;
+
+    my $error;
+
+    # read dynamic file names
+    my $runfiles = "$runpath/files";
+    my $files = read_config($runfiles);
+
+    # set path to logfile
+    my $logpath = $runpath . $SLASH . $files->unfolded_value('Log');
+
+    my $log_bytes = capture_merged {
+        try {
+            # call runner
+            runner($runpath, $logpath)
+
+        } catch {
+            # catch any error
+            $error = $@;
+        }
+    };
+
+    my $log = decode_utf8($log_bytes);
+
+    # append runner log to population log
+    path($logpath)->append_utf8($log) if length $log;
+
+    # add error if there was one
+    path($logpath)->append_utf8($error) if length $error;
+
+    # print log and die on error
+    if ($error) {
+        print encode_utf8($log)
+          if length $log && $ENV{'DUMP_LOGS'}//$NO eq $YES;
+        die encode_utf8("Runner died for $runpath: $error");
+    }
+
+    return;
+}
+
+=item runner(RUN_PATH)
+
+This routine provides the basic structure for all runners and runs the
+test located in RUN_PATH.
+
+=cut
+
+sub runner {
+    my ($runpath, @exclude)= @_;
+
+    # set a predictable locale
+    $ENV{'LC_ALL'} = 'C';
+
+    say encode_utf8($EMPTY);
+    say encode_utf8('------- Runner starts here -------');
+
+    # bail out if runpath does not exist
+    BAIL_OUT(encode_utf8("Cannot find test directory $runpath."))
+      unless -d $runpath;
+
+    # announce location
+    say encode_utf8("Running test at $runpath.");
+
+    # read dynamic file names
+    my $runfiles = "$runpath/files";
+    my $files = read_config($runfiles);
+
+    # get file age
+    my $spec_epoch = stat($runfiles)->mtime;
+
+    # read dynamic case data
+    my $rundescpath
+      = $runpath . $SLASH . $files->unfolded_value('Test-Specification');
+    my $testcase = read_config($rundescpath);
+
+    # get data age
+    $spec_epoch = max(stat($rundescpath)->mtime, $spec_epoch);
+    say encode_utf8('Specification is from : '. rfc822date($spec_epoch));
+
+    say encode_utf8($EMPTY);
+
+    # age of runner executable
+    my $runner_epoch = $ENV{'RUNNER_EPOCH'}//time;
+    say encode_utf8('Runner modified on   : '. rfc822date($runner_epoch));
+
+    # age of harness executable
+    my $harness_epoch = $ENV{'HARNESS_EPOCH'}//time;
+    say encode_utf8('Harness modified on  : '. rfc822date($harness_epoch));
+
+    # calculate rebuild threshold
+    my $threshold= max($spec_epoch, $runner_epoch, $harness_epoch);
+    say encode_utf8('Rebuild threshold is : '. rfc822date($threshold));
+
+    say encode_utf8($EMPTY);
+
+    # age of Lintian executable
+    my $lintian_epoch = $ENV{'LINTIAN_EPOCH'}//time;
+    say encode_utf8('Lintian modified on  : '. rfc822date($lintian_epoch));
+
+    my $testname = $testcase->unfolded_value('Testname');
+    # name of encapsulating directory should be that of test
+    my $expected_name = path($runpath)->basename;
+    die encode_utf8(
+        "Test in $runpath is called $testname instead of $expected_name")
+      unless $testname eq $expected_name;
+
+    # skip test if marked
+    my $skipfile = "$runpath/skip";
+    if (-e $skipfile) {
+        my $reason = path($skipfile)->slurp_utf8 || 'No reason given';
+        say encode_utf8("Skipping test: $reason");
+        plan skip_all => "(disabled) $reason";
+    }
+
+    # skip if missing prerequisites
+    my $missing = find_missing_prerequisites($testcase);
+    if (length $missing) {
+        say encode_utf8("Missing prerequisites: $missing");
+        plan skip_all => $missing;
+    }
+
+    # check test architectures
+    unless (length $ENV{'DEB_HOST_ARCH'}) {
+        say encode_utf8('DEB_HOST_ARCH is not set.');
+        BAIL_OUT(encode_utf8('DEB_HOST_ARCH is not set.'));
+    }
+    my $platforms = $testcase->unfolded_value('Test-Architectures');
+    if ($platforms ne 'any') {
+
+        my @wildcards = split($SPACE, $platforms);
+        my $match = 0;
+        for my $wildcard (@wildcards) {
+
+            my @command = (
+                qw{dpkg-architecture -a},
+                $ENV{'DEB_HOST_ARCH'}, '-i', $wildcard
+            );
+            run3(\@command, \undef, \undef, \undef);
+            my $status = ($? >> $WAIT_STATUS_SHIFT);
+
+            unless ($status) {
+                $match = 1;
+                last;
+            }
+        }
+        unless ($match) {
+            say encode_utf8('Architecture mismatch');
+            plan skip_all => encode_utf8('Architecture mismatch');
+        }
+    }
+
+    plan skip_all => 'No package found'
+      unless -e "$runpath/subject";
+
+    # set the testing plan
+    plan tests => 1;
+
+    my $subject = path("$runpath/subject")->realpath;
+
+    # get lintian subject
+    die encode_utf8('Could not get subject of Lintian examination.')
+      unless -e $subject;
+
+    # run lintian
+    $ENV{'LINTIAN_COVERAGE'}.= ",-db,./cover_db-$testname"
+      if exists $ENV{'LINTIAN_COVERAGE'};
+
+    my $lintian_command_line
+      = $testcase->unfolded_value('Lintian-Command-Line');
+    my $command
+      = "cd $runpath; $ENV{'LINTIAN_UNDER_TEST'} $lintian_command_line $subject";
+    say encode_utf8($command);
+    my ($output, $status) = capture_merged { system($command); };
+    $status >>= $WAIT_STATUS_SHIFT;
+
+    $output = decode_utf8($output)
+      if length $output;
+
+    say encode_utf8("$command exited with status $status.");
+    say encode_utf8($output) if $status == 1;
+
+    my $expected_status = $testcase->unfolded_value('Exit-Status');
+
+    my @errors;
+    push(@errors,
+        "Exit code $status differs from expected value $expected_status.")
+      if $testcase->declares('Exit-Status')
+      && $status != $expected_status;
+
+    # filter out some warnings if running under coverage
+    my @lines = split(/\n/, $output);
+    if (exists $ENV{LINTIAN_COVERAGE}) {
+        # Devel::Cover causes deep recursion warnings.
+        @lines = grep {
+            !m{^Deep [ ] recursion [ ] on [ ] subroutine [ ]
+           "[^"]+" [ ] at [ ] .*B/Deparse.pm [ ] line [ ]
+           \d+}xsm
+        } @lines;
+    }
+
+    # put output back together
+    $output = $EMPTY;
+    $output .= $_ . $NEWLINE for @lines;
+
+    die encode_utf8('No match strategy defined')
+      unless $testcase->declares('Match-Strategy');
+
+    my $match_strategy = $testcase->unfolded_value('Match-Strategy');
+
+    if ($match_strategy eq 'literal') {
+        push(@errors, check_literal($testcase, $runpath, $output));
+
+    } elsif ($match_strategy eq 'hints') {
+        push(@errors, check_hints($testcase, $runpath, $output));
+
+    } else {
+        die encode_utf8("Unknown match strategy $match_strategy.");
+    }
+
+    my $okay = !(scalar @errors);
+
+    if ($testcase->declares('Todo')) {
+
+        my $explanation = $testcase->unfolded_value('Todo');
+        diag encode_utf8("TODO ($explanation)");
+
+      TODO: {
+            local $TODO = $explanation;
+            ok($okay, 'Lintian passes for test marked TODO.');
+        }
+
+        return;
+    }
+
+    diag encode_utf8($_ . $NEWLINE) for @errors;
+
+    ok($okay, "Lintian passes for $testname");
+
+    return;
+}
+
+=item check_literal
+
+=cut
+
+sub check_literal {
+    my ($testcase, $runpath, $output) = @_;
+
+    # create expected output if it does not exist
+    my $expected = "$runpath/literal";
+    path($expected)->touch
+      unless -e $expected;
+
+    my $raw = "$runpath/literal.actual";
+    path($raw)->spew_utf8($output);
+
+    # run a sed-script if it exists
+    my $actual = "$runpath/literal.actual.parsed";
+    my $script = "$runpath/post-test";
+    if (-e $script) {
+        sed_hook($script, $raw, $actual);
+    } else {
+        die encode_utf8("Could not copy actual hints $raw to $actual: $!")
+          if system('cp', '-p', $raw, $actual);
+    }
+
+    return check_result($testcase, $runpath, $expected, $actual);
+}
+
+=item check_hints
+
+=cut
+
+sub check_hints {
+    my ($testcase, $runpath, $output) = @_;
+
+    # create expected hints if there are none; helps when calibrating new tests
+    my $expected = "$runpath/hints";
+    path($expected)->touch
+      unless -e $expected;
+
+    my $raw = "$runpath/hints.actual";
+    path($raw)->spew_utf8($output);
+
+    # run a sed-script if it exists
+    my $actual = "$runpath/hints.actual.parsed";
+    my $sedscript = "$runpath/post-test";
+    if (-e $sedscript) {
+        sed_hook($sedscript, $raw, $actual);
+    } else {
+        die encode_utf8("Could not copy actual hints $raw to $actual: $!")
+          if system('cp', '-p', $raw, $actual);
+    }
+
+    # calibrate hints; may write to $actual
+    my $calibrated = "$runpath/hints.specified.calibrated";
+    my $calscript = "$runpath/test-calibration";
+    if(-x $calscript) {
+        calibrate($calscript, $actual, $expected, $calibrated);
+    } else {
+        die encode_utf8(
+            "Could not copy expected hints $expected to $calibrated: $!")
+          if system('cp', '-p', $expected, $calibrated);
+    }
+
+    return check_result($testcase, $runpath, $calibrated, $actual);
+}
+
+=item check_result(DESC, EXPECTED, ACTUAL)
+
+This routine checks if the EXPECTED hints match the calibrated ACTUAL for the
+test described by DESC. For some additional checks, also need the ORIGINAL
+hints before calibration. Returns a list of errors, if there are any.
+
+=cut
+
+sub check_result {
+    my ($testcase, $runpath, $expectedpath, $actualpath) = @_;
+
+    my @errors;
+
+    my @expectedlines = path($expectedpath)->lines_utf8;
+    my @actuallines = path($actualpath)->lines_utf8;
+
+    push(@expectedlines, $NEWLINE)
+      unless @expectedlines;
+    push(@actuallines, $NEWLINE)
+      unless @actuallines;
+
+    my $match_strategy = $testcase->unfolded_value('Match-Strategy');
+
+    if ($match_strategy eq 'hints') {
+        @expectedlines
+          = reverse sort { order($a) cmp order($b) } @expectedlines;
+        @actuallines
+          = reverse sort { order($a) cmp order($b) } @actuallines;
+    }
+
+    my $diff = diff(\@expectedlines, \@actuallines, { CONTEXT => 0 });
+    my @difflines = split(/\n/, $diff);
+    chomp @difflines;
+
+    # diag encode_utf8("Difflines: $_") for @difflines;
+
+    if(@difflines) {
+
+        if ($match_strategy eq 'literal') {
+            push(@errors, 'Literal output does not match');
+
+        } elsif ($match_strategy eq 'hints') {
+
+            push(@errors, 'Hints do not match');
+
+            @difflines = reverse sort @difflines;
+            my $hintdiff;
+            $hintdiff .= $_ . $NEWLINE for @difflines;
+            path("$runpath/hintdiff")->spew_utf8($hintdiff // $EMPTY);
+
+        } else {
+            die encode_utf8("Unknown match strategy $match_strategy.");
+        }
+
+        push(@errors, $EMPTY);
+
+        push(@errors, '--- ' . abs2rel($expectedpath));
+        push(@errors, '+++ ' . abs2rel($actualpath));
+        push(@errors, @difflines);
+
+        push(@errors, $EMPTY);
+    }
+
+    # stop if the test is not about hints
+    return @errors
+      unless $match_strategy eq 'hints';
+
+    # get expected tags
+    my @expected = sort +get_tag_names($expectedpath);
+
+    #diag encode_utf8("=Expected tag: $_") for @expected;
+
+    # look out for tags being tested
+    my @related;
+
+    if (   $testcase->declares('Check')
+        && $testcase->unfolded_value('Check') ne 'all') {
+
+        my $profile = Lintian::Profile->new;
+        $profile->load(undef, undef, 0);
+
+        # use tags related to checks declared
+        my @check_names = $testcase->trimmed_list('Check');
+        my @unknown
+          = grep { !exists $profile->check_module_by_name->{$_} } @check_names;
+
+        die encode_utf8('Unknown Lintian checks: ' . join($SPACE, @unknown))
+          if @unknown;
+
+        push(@related, @{$profile->tag_names_for_check->{$_} // []})
+          for @check_names;
+
+        @related = sort @related;
+
+    } else {
+        # otherwise, look for all expected tags
+        @related = @expected;
+    }
+
+    #diag encode_utf8("#Related tag: $_") for @related;
+
+    # calculate Test-For and Test-Against; results are sorted
+    my $material = List::Compare->new(\@expected, \@related);
+    my @test_for = $material->get_intersection;
+    my @test_against = $material->get_Ronly;
+
+    #diag encode_utf8("+Test-For: $_") for @test_for;
+    #diag encode_utf8("-Test-Against (calculated): $_") for @test_against;
+
+    # get actual tags from output
+    my @actual = sort +get_tag_names($actualpath);
+
+    #diag encode_utf8("*Actual tag found: $_") for @actual;
+
+    # check for blacklisted tags; result is sorted
+    my @unexpected
+      = List::Compare->new(\@test_against, \@actual)->get_intersection;
+
+    # warn about unexpected tags
+    if (@unexpected) {
+        push(@errors, 'Unexpected tags:');
+        push(@errors, $INDENT . $_) for @unexpected;
+        push(@errors, $EMPTY);
+    }
+    # find tags not seen; result is sorted
+    my @missing = List::Compare->new(\@test_for, \@actual)->get_Lonly;
+
+    # warn about missing tags
+    if (@missing) {
+        push(@errors, 'Missing tags:');
+        push(@errors, $INDENT . $_) for @missing;
+        push(@errors, $EMPTY);
+    }
+
+    return @errors;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Test/Lintian/Templates.pm b/lib/Test/Lintian/Templates.pm
new file mode 100644
index 0000000..b52df15
--- /dev/null
+++ b/lib/Test/Lintian/Templates.pm
@@ -0,0 +1,348 @@
+# Copyright (C) 2018 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA
+
+package Test::Lintian::Templates;
+
+=head1 NAME
+
+Test::Lintian::Templates -- Helper routines dealing with templates
+
+=head1 SYNOPSIS
+
+use Test::Lintian::Templates qw(fill_template);
+
+my $data = { 'placeholder' => 'value' };
+my $file = '/path/to/generated/file';
+
+fill_template("$file.in", $file, $data);
+
+=head1 DESCRIPTION
+
+Routines for dealing with templates in Lintian test specifications.
+
+=cut
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+BEGIN {
+    our @EXPORT_OK = qw(
+      copy_skeleton_template_sets
+      remove_surplus_templates
+      fill_skeleton_templates
+      fill_whitelisted_templates
+      fill_all_templates
+      fill_template
+    );
+}
+
+use Carp;
+use Const::Fast;
+use List::Util qw(max);
+use File::Path qw(make_path);
+use File::Spec::Functions qw(rel2abs abs2rel);
+use File::Find::Rule;
+use File::stat;
+use Path::Tiny;
+use Text::Template;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Test::Lintian::ConfigFile qw(read_config);
+use Test::Lintian::Helper qw(copy_dir_contents);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+const my $DOT => q{.};
+const my $COMMA => q{,};
+const my $COLON => q{:};
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item copy_skeleton_template_sets(INSTRUCTIONS, RUN_PATH, SUITE, TEST_SET)
+
+Copies template sets belonging to SUITE into the test working directory
+RUN_PATH according to INSTRUCTIONS. The INSTRUCTIONS are the target
+directory relative to RUN_PATH followed by the name of the template set
+in parentheses. Multiple such instructions must be separated by commas.
+
+=cut
+
+sub copy_skeleton_template_sets {
+    my ($instructions, $runpath, $testset)= @_;
+
+    # populate working directory with specified template sets
+    for my $placement (split($COMMA, $instructions)) {
+
+        my ($relative, $name)
+          =($placement =~ qr/^\s*([^()\s]+)\s*\(([^()\s]+)\)\s*$/);
+
+        croak encode_utf8('No template destination specified in skeleton.')
+          unless length $relative;
+
+        croak encode_utf8('No template set specified in skeleton.')
+          unless length $name;
+
+        my $templatesetpath = "$testset/templates/$name";
+        croak encode_utf8(
+            "Cannot find template set '$name' at $templatesetpath.")
+          unless -d $templatesetpath;
+
+        say encode_utf8(
+            "Installing template set '$name'"
+              . (
+                $relative ne $DOT ? " to ./$relative." : $EMPTY
+              )
+        );
+
+        # create directory
+        my $destination = "$runpath/$relative";
+        make_path($destination);
+
+        # copy template set
+        copy_dir_contents($templatesetpath, $destination)
+          if -d $templatesetpath;
+    }
+    return;
+}
+
+=item remove_surplus_templates(SRC_DIR, TARGET_DIR)
+
+Removes from TARGET_DIR any templates that have corresponding originals
+in SRC_DIR.
+
+=cut
+
+sub remove_surplus_templates {
+    my ($source, $destination) = @_;
+
+    my @originals = File::Find::Rule->file->in($source);
+    foreach my $original (@originals) {
+        my $relative = abs2rel($original, $source);
+        my $template = rel2abs("$relative.in", $destination);
+
+        if (-e $template) {
+            unlink($template)
+              or die encode_utf8("Cannot unlink $template");
+        }
+    }
+    return;
+}
+
+=item fill_skeleton_templates(INSTRUCTIONS, HASH, EPOCH, RUN_PATH, TEST_SET)
+
+Fills the templates specified in INSTRUCTIONS using the data in HASH. Only
+fills templates when the generated files are not present or are older than
+either the file modification time of the template or the age of the data
+as evidenced by EPOCH. The INSTRUCTIONS are the target directory relative
+to RUN_PATH followed by the name of the whitelist in parentheses. Multiple
+instructions must be separated by commas.
+
+=cut
+
+sub fill_skeleton_templates {
+    my ($instructions, $testcase, $threshold, $runpath, $testset)= @_;
+
+    for my $target (split(/$COMMA/, $instructions)) {
+
+        my ($relative, $name)
+          =($target=~ qr/^\s*([^()\s]+)\s*(?:\(([^()\s]+)\))?\s*$/);
+
+        croak encode_utf8('No fill destination specified in skeleton.')
+          unless length $relative;
+
+        if (length $name) {
+
+            # template set
+            my $whitelistpath = "$testset/whitelists/$name";
+            croak encode_utf8(
+                "Cannot find template whitelist '$name' at $whitelistpath")
+              unless -e $whitelistpath;
+
+            say encode_utf8($EMPTY);
+
+            say encode_utf8(
+                'Generate files '
+                  . (
+                    $relative ne $DOT ? "in ./$relative " : $EMPTY
+                  )
+                  . "from templates using whitelist '$name'."
+            );
+            my $whitelist = read_config($whitelistpath);
+
+            my @candidates = $whitelist->trimmed_list('May-Generate');
+            my $destination = "$runpath/$relative";
+
+            say encode_utf8(
+                'Fill templates'
+                  . (
+                    $relative ne $DOT ? " in ./$relative" : $EMPTY
+                  )
+                  . $COLON
+                  . $SPACE
+                  . join($SPACE, @candidates)
+            );
+
+            foreach my $candidate (@candidates) {
+                my $generated = rel2abs($candidate, $destination);
+                my $template = "$generated.in";
+
+                # fill template if needed
+                fill_template($template, $generated, $testcase, $threshold)
+                  if -e $template;
+            }
+
+        }else {
+
+            # single file
+            say encode_utf8("Filling template: $relative");
+
+            my $generated = rel2abs($relative, $runpath);
+            my $template = "$generated.in";
+
+            # fill template if needed
+            fill_template($template, $generated, $testcase, $threshold)
+              if -e $template;
+        }
+    }
+    return;
+}
+
+=item fill_whitelisted_templates(DIR, WHITE_LIST, HASH, HASH_EPOCH)
+
+Generates all files in array WHITE_LIST relative to DIR from their templates,
+which are assumed to have the same file name but with extension '.in', using
+data provided in HASH. The optional argument HASH_EPOCH can be used to
+preserve files when no generation is necessary.
+
+=cut
+
+sub fill_whitelisted_templates {
+    my ($directory, $whitelistpath, $data, $data_epoch) = @_;
+
+    croak encode_utf8("No whitelist found at $whitelistpath")
+      unless -e $whitelistpath;
+
+    my $whitelist = read_config($whitelistpath);
+    my @list = $whitelist->trimmed_list('May-Generate');
+
+    foreach my $file (@list) {
+        my $generated = rel2abs($file, $directory);
+        my $template = "$generated.in";
+
+        # fill template if needed
+        fill_template($template, $generated, $data, $data_epoch)
+          if -e $template;
+    }
+    return;
+}
+
+=item fill_all_templates(HASH, DIR)
+
+Fills all templates in DIR with data from HASH.
+
+=cut
+
+sub fill_all_templates {
+    my ($data, $data_epoch, $directory) = @_;
+
+    my @templates = File::Find::Rule->name('*.in')->in($directory);
+    foreach my $template (@templates) {
+        my ($generated) = ($template =~ qr/^(.+?)\.in$/);
+
+        # fill template if needed
+        fill_template($template, $generated, $data, $data_epoch);
+    }
+    return;
+}
+
+=item fill_template(TEMPLATE, GENERATED, HASH, HASH_EPOCH, DELIMITERS)
+
+Fills template TEMPLATE with data from HASH and places the result in
+file GENERATED. When given HASH_EPOCH, will evaluate beforehand if a
+substitution is necessary based on file modification times. The optional
+parameter DELIMITERS can be used to change the standard delimiters.
+
+=cut
+
+sub fill_template {
+    my ($template, $generated, $data, $data_epoch, $delimiters) = @_;
+
+    my $generated_epoch
+      = length $generated  && -e $generated ? stat($generated)->mtime : 0;
+    my $template_epoch
+      = length $template && -e $template ? stat($template)->mtime : time;
+    my $threshold = max($template_epoch, $data_epoch//time);
+
+    if ($generated_epoch <= $threshold) {
+
+        my $filler= Text::Template->new(
+            TYPE => 'FILE',
+            DELIMITERS => ['[%', '%]'],
+            SOURCE => $template
+        );
+        croak encode_utf8(
+            "Cannot read template $template: $Text::Template::ERROR")
+          unless $filler;
+
+        open(my $handle, '>', $generated)
+          or croak encode_utf8("Could not open file $generated: $!");
+        $filler->fill_in(
+            OUTPUT => $handle,
+            HASH => $data,
+            DELIMITERS => $delimiters
+          )
+          or croak encode_utf8(
+            "Could not create file $generated from template $template");
+        close $handle
+          or carp encode_utf8("Could not close file $generated: $!");
+
+        # transfer file permissions from template to generated file
+        my $stat = stat($template)
+          or croak encode_utf8("stat $template failed: $!");
+        chmod $stat->mode, $generated
+          or croak encode_utf8("chmod $generated failed: $!");
+
+        # set mtime to $threshold
+        path($generated)->touch($threshold);
+    }
+
+    # delete template
+    if (-e $generated) {
+        unlink($template)
+          or die encode_utf8("Cannot unlink $template");
+    }
+
+    return;
+}
+
+=back
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Test/ScriptAge.pm b/lib/Test/ScriptAge.pm
new file mode 100644
index 0000000..dcab63b
--- /dev/null
+++ b/lib/Test/ScriptAge.pm
@@ -0,0 +1,109 @@
+# Copyright (C) 2019 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA
+
+package Test::ScriptAge;
+
+=head1 NAME
+
+Test::ScriptAge -- routines relating to the age of Perl scripts
+
+=head1 SYNOPSIS
+
+  my $executable_epoch = Test::ScriptAge::our_modification_epoch();
+  print encode_utf8('This script was last modified at ' . localtime($executable_epoch) . "\n");
+
+  my $perl_epoch = Test::ScriptAge::perl_modification_epoch();
+  print encode_utf8('Perl was last modified at ' . localtime($perl_epoch) . "\n");
+
+=head1 DESCRIPTION
+
+Routines to calculated modification times of Perl scripts.
+
+=cut
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Exporter qw(import);
+
+BEGIN {
+    our @EXPORT_OK = qw(
+      perl_modification_epoch
+      our_modification_epoch
+    );
+}
+
+use File::stat;
+use File::Spec::Functions qw(rel2abs);
+use List::Util qw(max);
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item perl_modification_epoch
+
+Calculate the time our Perl was last modified.
+
+=cut
+
+sub perl_modification_epoch {
+    my $perlpath = rel2abs($^X);
+    return stat($perlpath)->mtime;
+}
+
+=item our_modification_epoch
+
+Calculate the time our scripts, including all libraries, was last modified.
+
+=cut
+
+sub our_modification_epoch {
+    my (undef, $callerpath, undef) = caller;
+
+    my @paths = map { rel2abs($_) } ($callerpath, values %INC);
+    if (my @relative = grep { !/^\// } @paths){
+        warn encode_utf8(
+            'Relative paths in running_epoch: '.join(', ', @relative));
+    }
+    my @epochs = map { path($_)->stat->mtime } @paths;
+    return max @epochs;
+}
+
+=back
+
+=head1 AUTHOR
+
+Originally written by Felix Lechner <felix.lechner@lease-up.com> for Lintian.
+
+=head1 SEE ALSO
+
+lintian(1)
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et
diff --git a/lib/Test/StagedFileProducer.pm b/lib/Test/StagedFileProducer.pm
new file mode 100644
index 0000000..ada9069
--- /dev/null
+++ b/lib/Test/StagedFileProducer.pm
@@ -0,0 +1,314 @@
+# Copyright (C) 2018 Felix Lechner
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, you can find it on the World Wide
+# Web at https://www.gnu.org/copyleft/gpl.html, or write to the Free
+# Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
+# MA 02110-1301, USA
+
+package Test::StagedFileProducer;
+
+=head1 NAME
+
+Test::StagedFileProducer -- mtime-based file production engine
+
+=head1 SYNOPSIS
+
+  use Test::StagedFileProducer;
+
+  my $wherever = '/your/test/directory';
+
+  my $producer = Test::StagedFileProducer->new(path => $wherever);
+  $producer->exclude("$wherever/log", "$wherever/build-stamp");
+
+  my $output = "$wherever/file.out";
+  $producer->add_stage(
+        products => [$output],
+        build =>sub {
+            print encode_utf8("Building $output.\n");
+        },
+        skip =>sub {
+            print encode_utf8("Skipping $output.\n");
+        }
+  );
+
+  $producer->run(minimum_epoch => time, verbose => 1);
+
+=head1 DESCRIPTION
+
+Provides a way to define and stack file production stages that all
+depend on subsets of the same group of files.
+
+After the stages are defined, the processing engine takes an inventory
+of all files in a target directory. It excludes some files, like logs,
+that should not be considered.
+
+Each stage adds its own products to the list of files to be excluded
+before deciding whether to produce them. The decision is based on
+relative file modification times, in addition to a systemic rebuilding
+threshold. Before rebuilding, each stage asks a lower stage to make
+the same determination.
+
+The result is an engine with file production stages that depend on
+successively larger sets of files.
+
+=cut
+
+use v5.20;
+use warnings;
+use utf8;
+
+use Carp;
+use Const::Fast;
+use File::Find::Rule;
+use File::Spec::Functions qw(abs2rel);
+use File::stat;
+use List::Util qw(min max);
+use Path::Tiny;
+use Unicode::UTF8 qw(encode_utf8);
+
+use Test::Lintian::Helper qw(rfc822date);
+
+const my $EMPTY => q{};
+const my $SPACE => q{ };
+
+=head1 FUNCTIONS
+
+=over 4
+
+=item new(path => PATH)
+
+Create a new instance focused on files in directory PATH.
+
+=cut
+
+sub new {
+    my ($class, %params) = @_;
+
+    my $self = bless {}, $class;
+
+    croak encode_utf8('Cannot proceed without a path.')
+      unless exists $params{path};
+    $self->{path} = $params{path};
+
+    $self->{exclude} = [];
+    $self->{stages} = [];
+
+    return $self;
+}
+
+=item exclude(LIST)
+
+Excludes all absolute paths in LIST from all mtime comparisons.
+This is especially useful for logs. Calls to Path::Tiny->realpath
+are made to ensure the elements are canonical and have a chance
+of matching something returned by File::Find::Rule.
+
+=cut
+
+sub exclude {
+    my ($self, @list) = @_;
+
+    push(@{$self->{exclude}}, grep { defined } @list);
+
+    return;
+}
+
+=item add_stage(HASH)
+
+Add a stage defined by HASH to the processing engine for processing
+after stages previously added. HASH can define the following keys:
+
+$HASH{products} => LIST; a list of full-path filenames to be
+produced.
+
+$HASH{minimum_epoch} => EPOCH; an integer threshold for maximum age
+
+$HASH{build} => SUB; a sub executed when production is required.
+
+$HASH{skip} => SUB; a sub executed when production is not required.
+
+=cut
+
+sub add_stage {
+    my ($self, %stage) = @_;
+
+    push(@{$self->{stages}}, \%stage);
+
+    return;
+}
+
+=item run(PARAMETERS)
+
+Runs the defined engine using the given parameters, which are
+arranged in a matching list suitable for assignment to a hash.
+The following two parameters are currently available:
+
+minimum_epoch => EPOCH; a systemic threshold, in epochs, below
+which rebuilding is mandatory for any product.
+
+verbose => BOOLEAN; an option to enable more verbose reporting
+
+=cut
+
+sub run {
+    my ($self, %params) = @_;
+
+    $self->{minimum_epoch} = $params{minimum_epoch} // 0;
+    $self->{verbose} = $params{verbose} // 0;
+
+    # take an mtime inventory of all files in path
+    $self->{mtimes}
+      = { map { $_ => path($_)->stat->mtime }
+          File::Find::Rule->file->in($self->{path}) };
+
+    say encode_utf8(
+        'Found the following file modification times (most recent first):')
+      if $self->{verbose};
+
+    my @ordered= reverse sort { $self->{mtimes}{$a} <=> $self->{mtimes}{$b} }
+      keys %{$self->{mtimes}};
+    foreach my $file (@ordered) {
+        my $relative = abs2rel($file, $self->{path});
+        say encode_utf8(rfc822date($self->{mtimes}{$file}) . " : $relative")
+          if $self->{verbose};
+    }
+
+    $self->_process_remaining_stages(@{$self->{exclude}});
+
+    return;
+}
+
+=item _process_remaining_stages(LIST)
+
+An internal subroutine that is used recursively to execute
+the stages. The list passed describes the list of files to
+be excluded from subsequent mtime calculations.
+
+Please note that the bulk of the execution takes place
+after calling the next lower stage. That is to ensure that
+any lower build targets (or products, in our parlance) are
+met before the present stage attempts to do its job.
+
+=cut
+
+sub _process_remaining_stages {
+    my ($self, @exclude) = @_;
+
+    if (scalar @{$self->{stages}}) {
+
+        # get the next processing stage
+        my %stage = %{ pop(@{$self->{stages}}) };
+
+        # add our products to the list of files excluded
+        my @products = grep { defined } @{$stage{products}//[]};
+        push(@exclude, @products);
+
+        # pass to next lower stage for potential rebuilding
+        $self->_process_remaining_stages(@exclude);
+
+        # get good paths that will match those of File::Find
+        @exclude = map { path($_)->realpath } @exclude;
+
+        say encode_utf8($EMPTY) if $self->{verbose};
+
+        my @relative = sort map { abs2rel($_, $self->{path}) } @products;
+        say encode_utf8(
+            'Considering production of: ' . join($SPACE, @relative))
+          if $self->{verbose};
+
+        say encode_utf8('Excluding: '
+              . join($SPACE, sort map { abs2rel($_, $self->{path}) } @exclude))
+          if $self->{verbose};
+
+        my %relevant = %{$self->{mtimes}};
+        delete @relevant{@exclude};
+
+# my @ordered= reverse sort { $relevant{$a} <=> $relevant{$b} }
+#   keys %relevant;
+# foreach my $file (@ordered) {
+#   say encode_utf8(rfc822date($relevant{$file}) . ' : ' . abs2rel($file, $self->{path}))
+#     if $self->{verbose};
+# }
+
+        say encode_utf8($EMPTY) if $self->{verbose};
+
+        my $file_epoch = (max(values %relevant))//time;
+        say encode_utf8(
+            'Input files modified on      : '. rfc822date($file_epoch))
+          if $self->{verbose};
+
+        my $systemic_minimum_epoch = $self->{minimum_epoch} // 0;
+        say encode_utf8('Systemic minimum epoch is    : '
+              . rfc822date($systemic_minimum_epoch))
+          if $self->{verbose};
+
+        my $stage_minimum_epoch = $stage{minimum_epoch} // 0;
+        say encode_utf8('Stage minimum epoch is       : '
+              . rfc822date($stage_minimum_epoch))
+          if $self->{verbose};
+
+        my $threshold
+          = max($stage_minimum_epoch, $systemic_minimum_epoch, $file_epoch);
+        say encode_utf8(
+            'Rebuild threshold is         : '. rfc822date($threshold))
+          if $self->{verbose};
+
+        say encode_utf8($EMPTY) if $self->{verbose};
+
+        my $product_epoch
+          = min(map { -e ? path($_)->stat->mtime : 0 } @products);
+        if($product_epoch) {
+            say encode_utf8(
+                'Products modified on         : '. rfc822date($product_epoch))
+              if $self->{verbose};
+        } else {
+            say encode_utf8('At least one product is not present.')
+              if $self->{verbose};
+        }
+
+        # not producing if times are equal; resolution 1 sec
+        if ($product_epoch < $threshold) {
+
+            say encode_utf8('Producing: ' . join($SPACE, @relative))
+              if $self->{verbose};
+
+            $stage{build}->() if exists $stage{build};
+
+            # sometimes the products are not the newest files
+            path($_)->touch(time) for @products;
+
+        } else {
+
+            say encode_utf8(
+                'Skipping production of: ' . join($SPACE, @relative))
+              if $self->{verbose};
+
+            $stage{skip}->() if exists $stage{skip};
+        }
+    }
+
+    return;
+}
+
+=back
+
+=cut
+
+1;
+
+# Local Variables:
+# indent-tabs-mode: nil
+# cperl-indent-level: 4
+# End:
+# vim: syntax=perl sw=4 sts=4 sr et