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File:Dpkg/Compression/Process.pm
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1# Copyright © 2008-2010 Raphaël Hertzog <hertzog@debian.org>
2# Copyright © 2008-2022 Guillem Jover <guillem@debian.org>
3#
4# This program is free software; you can redistribute it and/or modify
5# it under the terms of the GNU General Public License as published by
6# the Free Software Foundation; either version 2 of the License, or
7# (at your option) any later version.
8#
9# This program is distributed in the hope that it will be useful,
10# but WITHOUT ANY WARRANTY; without even the implied warranty of
11# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12# GNU General Public License for more details.
13#
14# You should have received a copy of the GNU General Public License
15# along with this program.  If not, see <https://www.gnu.org/licenses/>.
16
17=encoding utf8
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=head1 NAME

Dpkg::Compression::Process - run compression/decompression processes

=head1 DESCRIPTION

This module provides an object oriented interface to run and manage
compression/decompression processes.

=cut
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30package Dpkg::Compression::Process 1.00;
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use strict;
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use warnings;
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use Carp;
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use Dpkg::Compression;
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use Dpkg::ErrorHandling;
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use Dpkg::Gettext;
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use Dpkg::IPC;
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=head1 METHODS

=over 4

=item $proc = Dpkg::Compression::Process->new(%opts)

Create a new instance of the object. Supported options are "compression"
and "compression_level" (see corresponding set_* functions).

=cut
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53sub new {
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    my ($this, %args) = @_;
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    my $class = ref($this) || $this;
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    my $self = {};
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    bless $self, $class;
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    $self->set_compression($args{compression} || compression_get_default());
59    $self->set_compression_level($args{compression_level} ||
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        compression_get_default_level());
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    return $self;
62}
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=item $proc->set_compression($comp)

Select the compression method to use. It errors out if the method is not
supported according to compression_is_supported() (of
L<Dpkg::Compression>).

=cut
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72sub set_compression {
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    my ($self, $method) = @_;
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    error(g_('%s is not a supported compression method'), $method)
75        unless compression_is_supported($method);
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    $self->{compression} = $method;
77}
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=item $proc->set_compression_level($level)

Select the compression level to use. It errors out if the level is not
valid according to compression_is_valid_level() (of
L<Dpkg::Compression>).

=cut
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87sub set_compression_level {
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    my ($self, $level) = @_;
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    compression_set_level($self->{compression}, $level);
91}
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=item @exec = $proc->get_compress_cmdline()

=item @exec = $proc->get_uncompress_cmdline()

Returns a list ready to be passed to exec(), its first element is the
program name (either for compression or decompression) and the following
elements are parameters for the program.

When executed the program acts as a filter between its standard input
and its standard output.

=cut
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106sub get_compress_cmdline {
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    my $self = shift;
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    return compression_get_cmdline_compress($self->{compression});
110}
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112sub get_uncompress_cmdline {
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    my $self = shift;
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    return compression_get_cmdline_decompress($self->{compression});
116}
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118sub _check_opts {
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    my ($self, %opts) = @_;
120    # Check for proper cleaning before new start
121    error(g_('Dpkg::Compression::Process can only start one subprocess at a time'))
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        if $self->{pid};
123    # Check options
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    my $to = my $from = 0;
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    foreach my $thing (qw(file handle string pipe)) {
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        $to++ if $opts{"to_$thing"};
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        $from++ if $opts{"from_$thing"};
128    }
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    croak 'exactly one to_* parameter is needed' if $to != 1;
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    croak 'exactly one from_* parameter is needed' if $from != 1;
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    return %opts;
132}
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=item $proc->compress(%opts)

Starts a compressor program. You must indicate where it will read its
uncompressed data from and where it will write its compressed data to.
This is accomplished by passing one parameter C<to_*> and one parameter
C<from_*> as accepted by Dpkg::IPC::spawn().

You must call wait_end_process() after having called this method to
properly close the sub-process (and verify that it exited without error).

=cut
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146sub compress {
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    my ($self, %opts) = @_;
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    $self->_check_opts(%opts);
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    my @prog = $self->get_compress_cmdline();
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    $opts{exec} = \@prog;
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    $self->{cmdline} = "@prog";
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    $self->{pid} = spawn(%opts);
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    delete $self->{pid} if $opts{to_string}; # wait_child already done
155}
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=item $proc->uncompress(%opts)

Starts a decompressor program. You must indicate where it will read its
compressed data from and where it will write its uncompressed data to.
This is accomplished by passing one parameter C<to_*> and one parameter
C<from_*> as accepted by Dpkg::IPC::spawn().

You must call wait_end_process() after having called this method to
properly close the sub-process (and verify that it exited without error).

=cut
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169sub uncompress {
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    my ($self, %opts) = @_;
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    $self->_check_opts(%opts);
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    my @prog = $self->get_uncompress_cmdline();
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    $opts{exec} = \@prog;
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    $self->{cmdline} = "@prog";
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    $self->{pid} = spawn(%opts);
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    delete $self->{pid} if $opts{to_string}; # wait_child already done
178}
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=item $proc->wait_end_process(%opts)

Call Dpkg::IPC::wait_child() to wait until the sub-process has exited
and verify its return code. Any given option will be forwarded to
the wait_child() function. Most notably you can use the "nocheck" option
to verify the return code yourself instead of letting wait_child() do
it for you.

=cut
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190sub wait_end_process {
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    my ($self, %opts) = @_;
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    $opts{cmdline} //= $self->{cmdline};
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    wait_child($self->{pid}, %opts) if $self->{pid};
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    delete $self->{pid};
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    delete $self->{cmdline};
196}
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198=back
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=head1 CHANGES

=head2 Version 1.00 (dpkg 1.15.6)

Mark the module as public.

=cut
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2081;