Linux ip-172-26-7-228 5.4.0-1103-aws #111~18.04.1-Ubuntu SMP Tue May 23 20:04:10 UTC 2023 x86_64
Your IP : 3.145.78.203
# Copyright © 2010 Raphaël Hertzog <hertzog@debian.org>
# Copyright © 2010-2013 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, see <https://www.gnu.org/licenses/>.
package Dpkg::Compression;
use strict;
use warnings;
our $VERSION = '1.02';
our @EXPORT = qw(
$compression_re_file_ext
compression_is_supported
compression_get_list
compression_get_property
compression_guess_from_filename
compression_get_file_extension_regex
compression_get_default
compression_set_default
compression_get_default_level
compression_set_default_level
compression_is_valid_level
);
use Exporter qw(import);
use Config;
use Dpkg::ErrorHandling;
use Dpkg::Gettext;
=encoding utf8
=head1 NAME
Dpkg::Compression - simple database of available compression methods
=head1 DESCRIPTION
This modules provides a few public functions and a public regex to
interact with the set of supported compression methods.
=cut
my $COMP = {
gzip => {
file_ext => 'gz',
comp_prog => [ 'gzip', '--no-name' ],
decomp_prog => [ 'gunzip' ],
default_level => 9,
},
bzip2 => {
file_ext => 'bz2',
comp_prog => [ 'bzip2' ],
decomp_prog => [ 'bunzip2' ],
default_level => 9,
},
lzma => {
file_ext => 'lzma',
comp_prog => [ 'xz', '--format=lzma' ],
decomp_prog => [ 'unxz', '--format=lzma' ],
default_level => 6,
},
xz => {
file_ext => 'xz',
comp_prog => [ 'xz' ],
decomp_prog => [ 'unxz' ],
default_level => 6,
},
};
#
# XXX: The gzip package in Debian at some point acquired a Debian-specific
# --rsyncable option via a vendor patch. Which is not present in most of the
# major distributions, dpkg downstream systems, nor gzip upstream, who have
# stated they will most probably not accept it because people should be using
# pigz instead.
#
# This option should have never been accepted in dpkg, ever. But removing it
# now would probably cause demands for tarring and feathering. In addition
# we cannot use the Dpkg::Vendor logic because that would cause circular
# module dependencies. The whole affair is pretty disgusting really.
#
# Check the perl Config to discern Debian and hopefully derivatives too.
#
if ($Config{cf_by} eq 'Debian Project') {
push @{$COMP->{gzip}->{comp_prog}}, '--rsyncable';
}
# XXX: Backwards compatibility, stop exporting on VERSION 2.00.
## no critic (Variables::ProhibitPackageVars)
our $default_compression = 'xz';
our $default_compression_level = undef;
my $regex = join '|', map { $_->{file_ext} } values %$COMP;
our $compression_re_file_ext = qr/(?:$regex)/;
## use critic
=head1 FUNCTIONS
=over 4
=item @list = compression_get_list()
Returns a list of supported compression methods (sorted alphabetically).
=cut
sub compression_get_list {
my @list = sort keys %$COMP;
return @list;
}
=item compression_is_supported($comp)
Returns a boolean indicating whether the give compression method is
known and supported.
=cut
sub compression_is_supported {
my $comp = shift;
return exists $COMP->{$comp};
}
=item compression_get_property($comp, $property)
Returns the requested property of the compression method. Returns undef if
either the property or the compression method doesn't exist. Valid
properties currently include "file_ext" for the file extension,
"default_level" for the default compression level,
"comp_prog" for the name of the compression program and "decomp_prog" for
the name of the decompression program.
=cut
sub compression_get_property {
my ($comp, $property) = @_;
return unless compression_is_supported($comp);
return $COMP->{$comp}{$property} if exists $COMP->{$comp}{$property};
return;
}
=item compression_guess_from_filename($filename)
Returns the compression method that is likely used on the indicated
filename based on its file extension.
=cut
sub compression_guess_from_filename {
my $filename = shift;
foreach my $comp (compression_get_list()) {
my $ext = compression_get_property($comp, 'file_ext');
if ($filename =~ /^(.*)\.\Q$ext\E$/) {
return $comp;
}
}
return;
}
=item $regex = compression_get_file_extension_regex()
Returns a regex that matches a file extension of a file compressed with
one of the supported compression methods.
=cut
sub compression_get_file_extension_regex {
return $compression_re_file_ext;
}
=item $comp = compression_get_default()
Return the default compression method. It is "xz" unless
C<compression_set_default> has been used to change it.
=item compression_set_default($comp)
Change the default compression method. Errors out if the
given compression method is not supported.
=cut
sub compression_get_default {
return $default_compression;
}
sub compression_set_default {
my $method = shift;
error(g_('%s is not a supported compression'), $method)
unless compression_is_supported($method);
$default_compression = $method;
}
=item $level = compression_get_default_level()
Return the default compression level used when compressing data. It's "9"
for "gzip" and "bzip2", "6" for "xz" and "lzma", unless
C<compression_set_default_level> has been used to change it.
=item compression_set_default_level($level)
Change the default compression level. Passing undef as the level will
reset it to the compressor specific default, otherwise errors out if the
level is not valid (see C<compression_is_valid_level>).
=cut
sub compression_get_default_level {
if (defined $default_compression_level) {
return $default_compression_level;
} else {
return compression_get_property($default_compression, 'default_level');
}
}
sub compression_set_default_level {
my $level = shift;
error(g_('%s is not a compression level'), $level)
if defined($level) and not compression_is_valid_level($level);
$default_compression_level = $level;
}
=item compression_is_valid_level($level)
Returns a boolean indicating whether $level is a valid compression level
(it must be either a number between 1 and 9 or "fast" or "best")
=cut
sub compression_is_valid_level {
my $level = shift;
return $level =~ /^([1-9]|fast|best)$/;
}
=back
=head1 CHANGES
=head2 Version 1.02 (dpkg 1.17.2)
New function: compression_get_file_extension_regex()
Deprecated variables: $default_compression, $default_compression_level
and $compression_re_file_ext
=head2 Version 1.01 (dpkg 1.16.1)
Default compression level is not global any more, it is per compressor type.
=head2 Version 1.00 (dpkg 1.15.6)
Mark the module as public.
=cut
1;
|