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#!/usr/bin/env perl
use strict;
use warnings;
my @entries = (
# filename mode type content
['./PaxHeaders/file', oct(644), 'x', "57 SCHILY.xattr.security.capability=\x01\0\0\x02\0\x20\0\0\0\0\0\0\0\0\0\0\0\0\0\0\x0a"],
['file', oct(644), 0, ''],
);
my $num_entries = 0;
foreach my $file (@entries) {
my ($fname, $mode, $type, $content) = @{$file};
my $entry = pack(
'a100 a8 a8 a8 a12 a12 A8 a1 a100 a6 a2 a32 a32 a8 a8 a155 x12',
$fname,
sprintf('%07o', $mode),
sprintf('%07o', 0), # uid
sprintf('%07o', 0), # gid
sprintf('%011o', length $content), # size
sprintf('%011o', 0), # mtime
'', # checksum
$type,
'', # linkname
"ustar", # magic
"00", # version
'', # username
'', # groupname
'', # dev major
'', # dev minor
'', # prefix
);
# compute and insert checksum
substr($entry, 148, 7)
= sprintf("%06o\0", unpack("%16C*", $entry));
print $entry;
$num_entries += 1;
if (length $content) {
print(pack 'a512', $content);
$num_entries += 1;
}
}
# https://www.gnu.org/software/tar/manual/html_node/Standard.html
#
# Physically, an archive consists of a series of file entries terminated by an
# end-of-archive entry, which consists of two 512 blocks of zero bytes. At the
# end of the archive file there are two 512-byte blocks filled with binary
# zeros as an end-of-file marker.
print(pack 'a512', '');
print(pack 'a512', '');
$num_entries += 2;
# https://www.gnu.org/software/tar/manual/html_section/tar_76.html
#
# Some devices requires that all write operations be a multiple of a certain
# size, and so, tar pads the archive out to the next record boundary.
#
# The default blocking factor is 20. With a block size of 512 bytes, we get a
# record size of 10240.
for (my $i = $num_entries ; $i < 20 ; $i++) {
print(pack 'a512', '');
}
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