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# 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
|
