1# Copyright © 2008-2010 Raphaël Hertzog <hertzog@debian.org>
2#
3# This program is free software; you can redistribute it and/or modify
4# it under the terms of the GNU General Public License as published by
5# the Free Software Foundation; either version 2 of the License, or
6# (at your option) any later version.
7#
8# This program is distributed in the hope that it will be useful,
9# but WITHOUT ANY WARRANTY; without even the implied warranty of
10# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11# GNU General Public License for more details.
12#
13# You should have received a copy of the GNU General Public License
14# along with this program.  If not, see <https://www.gnu.org/licenses/>.
15
16package Dpkg::Compression::Process;
17
18use strict;
19use warnings;
20
21our $VERSION = '1.00';
22
23use Carp;
24
25use Dpkg::Compression;
26use Dpkg::ErrorHandling;
27use Dpkg::Gettext;
28use Dpkg::IPC;
29
30=encoding utf8
31
32=head1 NAME
33
34Dpkg::Compression::Process - run compression/decompression processes
35
36=head1 DESCRIPTION
37
38This module provides an object oriented interface to run and manage
39compression/decompression processes.
40
41=head1 METHODS
42
43=over 4
44
45=item $proc = Dpkg::Compression::Process->new(%opts)
46
47Create a new instance of the object. Supported options are "compression"
48and "compression_level" (see corresponding set_* functions).
49
50=cut
51
52sub new {
53    my ($this, %args) = @_;
54    my $class = ref($this) || $this;
55    my $self = {};
56    bless $self, $class;
57    $self->set_compression($args{compression} || compression_get_default());
58    $self->set_compression_level($args{compression_level} ||
59	    compression_get_default_level());
60    return $self;
61}
62
63=item $proc->set_compression($comp)
64
65Select the compression method to use. It errors out if the method is not
66supported according to C<compression_is_supported> (of
67B<Dpkg::Compression>).
68
69=cut
70
71sub set_compression {
72    my ($self, $method) = @_;
73    error(g_('%s is not a supported compression method'), $method)
74	    unless compression_is_supported($method);
75    $self->{compression} = $method;
76}
77
78=item $proc->set_compression_level($level)
79
80Select the compression level to use. It errors out if the level is not
81valid according to C<compression_is_valid_level> (of
82B<Dpkg::Compression>).
83
84=cut
85
86sub set_compression_level {
87    my ($self, $level) = @_;
88    error(g_('%s is not a compression level'), $level)
89	    unless compression_is_valid_level($level);
90    $self->{compression_level} = $level;
91}
92
93=item @exec = $proc->get_compress_cmdline()
94
95=item @exec = $proc->get_uncompress_cmdline()
96
97Returns a list ready to be passed to C<exec>, its first element is the
98program name (either for compression or decompression) and the following
99elements are parameters for the program.
100
101When executed the program acts as a filter between its standard input
102and its standard output.
103
104=cut
105
106sub get_compress_cmdline {
107    my $self = shift;
108    my @prog = (@{compression_get_property($self->{compression}, 'comp_prog')});
109    my $level = '-' . $self->{compression_level};
110    $level = '--' . $self->{compression_level}
111	    if $self->{compression_level} !~ m/^[1-9]$/;
112    push @prog, $level;
113    return @prog;
114}
115
116sub get_uncompress_cmdline {
117    my $self = shift;
118    return (@{compression_get_property($self->{compression}, 'decomp_prog')});
119}
120
121sub _sanity_check {
122    my ($self, %opts) = @_;
123    # Check for proper cleaning before new start
124    error(g_('Dpkg::Compression::Process can only start one subprocess at a time'))
125	    if $self->{pid};
126    # Check options
127    my $to = my $from = 0;
128    foreach my $thing (qw(file handle string pipe)) {
129        $to++ if $opts{"to_$thing"};
130        $from++ if $opts{"from_$thing"};
131    }
132    croak 'exactly one to_* parameter is needed' if $to != 1;
133    croak 'exactly one from_* parameter is needed' if $from != 1;
134    return %opts;
135}
136
137=item $proc->compress(%opts)
138
139Starts a compressor program. You must indicate where it will read its
140uncompressed data from and where it will write its compressed data to.
141This is accomplished by passing one parameter C<to_*> and one parameter
142C<from_*> as accepted by B<Dpkg::IPC::spawn>.
143
144You must call C<wait_end_process> after having called this method to
145properly close the sub-process (and verify that it exited without error).
146
147=cut
148
149sub compress {
150    my ($self, %opts) = @_;
151
152    $self->_sanity_check(%opts);
153    my @prog = $self->get_compress_cmdline();
154    $opts{exec} = \@prog;
155    $self->{cmdline} = "@prog";
156    $self->{pid} = spawn(%opts);
157    delete $self->{pid} if $opts{to_string}; # wait_child already done
158}
159
160=item $proc->uncompress(%opts)
161
162Starts a decompressor program. You must indicate where it will read its
163compressed data from and where it will write its uncompressed data to.
164This is accomplished by passing one parameter C<to_*> and one parameter
165C<from_*> as accepted by B<Dpkg::IPC::spawn>.
166
167You must call C<wait_end_process> after having called this method to
168properly close the sub-process (and verify that it exited without error).
169
170=cut
171
172sub uncompress {
173    my ($self, %opts) = @_;
174
175    $self->_sanity_check(%opts);
176    my @prog = $self->get_uncompress_cmdline();
177    $opts{exec} = \@prog;
178    $self->{cmdline} = "@prog";
179    $self->{pid} = spawn(%opts);
180    delete $self->{pid} if $opts{to_string}; # wait_child already done
181}
182
183=item $proc->wait_end_process(%opts)
184
185Call B<Dpkg::IPC::wait_child> to wait until the sub-process has exited
186and verify its return code. Any given option will be forwarded to
187the C<wait_child> function. Most notably you can use the "nocheck" option
188to verify the return code yourself instead of letting C<wait_child> do
189it for you.
190
191=cut
192
193sub wait_end_process {
194    my ($self, %opts) = @_;
195    $opts{cmdline} //= $self->{cmdline};
196    wait_child($self->{pid}, %opts) if $self->{pid};
197    delete $self->{pid};
198    delete $self->{cmdline};
199}
200
201=back
202
203=head1 CHANGES
204
205=head2 Version 1.00 (dpkg 1.15.6)
206
207Mark the module as public.
208
209=cut
210
2111;
212