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third_party/dpkg-dev/scripts/Dpkg/Checksums.pm

+# Copyright © 2008 Frank Lichtenheld <djpig@debian.org>
+# Copyright © 2010 Raphaël Hertzog <hertzog@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::Checksums;
+
+use strict;
+use warnings;
+
+our $VERSION = '1.00';
+
+use Dpkg;
+use Dpkg::Gettext;
+use Dpkg::ErrorHandling;
+use Dpkg::IPC;
+
+use Exporter qw(import);
+our @EXPORT = qw(checksums_get_list checksums_is_supported
+                 checksums_get_property);
+
+=encoding utf8
+
+=head1 NAME
+
+Dpkg::Checksums - generate and manipulate file checksums
+
+=head1 DESCRIPTION
+
+This module provides an object that can generate and manipulate
+various file checksums as well as some methods to query information
+about supported checksums.
+
+=head1 EXPORTED FUNCTIONS
+
+=over 4
+
+=cut
+
+my $CHECKSUMS = {
+    md5 => {
+        program => [ 'md5sum' ],
+        regex => qr/[0-9a-f]{32}/,
+    },
+    sha1 => {
+        program => [ 'sha1sum' ],
+        regex => qr/[0-9a-f]{40}/,
+    },
+    sha256 => {
+        program => [ 'sha256sum' ],
+        regex => qr/[0-9a-f]{64}/,
+    },
+};
+
+=item @list = checksums_get_list()
+
+Returns the list of supported checksums algorithms.
+
+=cut
+
+sub checksums_get_list() {
+    my @list = sort keys %{$CHECKSUMS};
+    return @list;
+}
+
+=item $bool = checksums_is_supported($alg)
+
+Returns a boolean indicating whether the given checksum algorithm is
+supported. The checksum algorithm is case-insensitive.
+
+=cut
+
+sub checksums_is_supported($) {
+    my ($alg) = @_;
+    return exists $CHECKSUMS->{lc($alg)};
+}
+
+=item $value = checksums_get_property($alg, $property)
+
+Returns the requested property of the checksum algorithm. Returns undef if
+either the property or the checksum algorithm doesn't exist. Valid
+properties currently include "program" (returns an array reference with
+a program name and parameters required to compute the checksum of the
+filename given as last parameter) and "regex" for the regular expression
+describing the common string representation of the checksum (as output
+by the program that generates it).
+
+=cut
+
+sub checksums_get_property($$) {
+    my ($alg, $property) = @_;
+    return unless checksums_is_supported($alg);
+    return $CHECKSUMS->{lc($alg)}{$property};
+}
+
+=back
+
+=head1 OBJECT METHODS
+
+=over 4
+
+=item my $ck = Dpkg::Checksums->new()
+
+Create a new Dpkg::Checksums object. This object is able to store
+the checksums of several files to later export them or verify them.
+
+=cut
+
+sub new {
+    my ($this, %opts) = @_;
+    my $class = ref($this) || $this;
+
+    my $self = {};
+    bless $self, $class;
+    $self->reset();
+
+    return $self;
+}
+
+=item $ck->reset()
+
+Forget about all checksums stored. The object is again in the same state
+as if it was newly created.
+
+=cut
+
+sub reset {
+    my ($self) = @_;
+    $self->{files} = [];
+    $self->{checksums} = {};
+    $self->{size} = {};
+}
+
+=item $ck->add_from_file($filename, %opts)
+
+Add checksums information for the file $filename. The file must exists
+for the call to succeed. If you don't want the given filename to appear
+when you later export the checksums you might want to set the "key"
+option with the public name that you want to use. Also if you don't want
+to generate all the checksums, you can pass an array reference of the
+wanted checksums in the "checksums" option.
+
+It the object already contains checksums information associated the
+filename (or key), it will error out if the newly computed information
+does not match what's stored.
+
+=cut
+
+sub add_from_file {
+    my ($self, $file, %opts) = @_;
+    my $key = exists $opts{key} ? $opts{key} : $file;
+    my @alg;
+    if (exists $opts{checksums}) {
+        push @alg, map { lc($_) } @{$opts{checksums}};
+    } else {
+        push @alg, checksums_get_list();
+    }
+
+    push @{$self->{files}}, $key unless exists $self->{size}{$key};
+    (my @s = stat($file)) or syserr(_g('cannot fstat file %s'), $file);
+    if (exists $self->{size}{$key} and $self->{size}{$key} != $s[7]) {
+        error(_g('file %s has size %u instead of expected %u'),
+              $file, $s[7], $self->{size}{$key});
+    }
+    $self->{size}{$key} = $s[7];
+
+    foreach my $alg (@alg) {
+        my @exec = (@{$CHECKSUMS->{$alg}{program}}, $file);
+        my $regex = $CHECKSUMS->{$alg}{regex};
+        my $output;
+        spawn(exec => \@exec, to_string => \$output);
+        if ($output =~ /^($regex)(\s|$)/m) {
+            my $newsum = $1;
+            if (exists $self->{checksums}{$key}{$alg} and
+                $self->{checksums}{$key}{$alg} ne $newsum) {
+                error(_g('file %s has checksum %s instead of expected %s (algorithm %s)'),
+                      $file, $newsum, $self->{checksums}{$key}{$alg}, $alg);
+            }
+            $self->{checksums}{$key}{$alg} = $newsum;
+        } else {
+            error(_g("checksum program gave bogus output `%s'"), $output);
+        }
+    }
+}
+
+=item $ck->add_from_string($alg, $value)
+
+Add checksums of type $alg that are stored in the $value variable.
+$value can be multi-lines, each line should be a space separated list
+of checksum, file size and filename. Leading or trailing spaces are
+not allowed.
+
+It the object already contains checksums information associated to the
+filenames, it will error out if the newly read information does not match
+what's stored.
+
+=cut
+
+sub add_from_string {
+    my ($self, $alg, $fieldtext) = @_;
+    $alg = lc($alg);
+    my $rx_fname = qr/[0-9a-zA-Z][-+:.,=0-9a-zA-Z_~]+/;
+    my $regex = checksums_get_property($alg, 'regex');
+    my $checksums = $self->{checksums};
+
+    for my $checksum (split /\n */, $fieldtext) {
+        next if $checksum eq '';
+        unless ($checksum =~ m/^($regex)\s+(\d+)\s+($rx_fname)$/) {
+            error(_g('invalid line in %s checksums string: %s'),
+                  $alg, $checksum);
+        }
+        my ($sum, $size, $file) = ($1, $2, $3);
+        if (exists($checksums->{$file}{$alg})
+            and $checksums->{$file}{$alg} ne $sum) {
+            error(_g("conflicting checksums '%s' and '%s' for file '%s'"),
+                  $checksums->{$file}{$alg}, $sum, $file);
+        }
+        if (exists $self->{size}{$file} and $self->{size}{$file} != $size) {
+            error(_g("conflicting file sizes '%u' and '%u' for file '%s'"),
+                  $self->{size}{$file}, $size, $file);
+        }
+        push @{$self->{files}}, $file unless exists $self->{size}{$file};
+        $checksums->{$file}{$alg} = $sum;
+        $self->{size}{$file} = $size;
+    }
+}
+
+=item $ck->add_from_control($control, %opts)
+
+Read checksums from Checksums-* fields stored in the Dpkg::Control object
+$control. It uses $self->add_from_string() on the field values to do the
+actual work.
+
+If the option "use_files_for_md5" evaluates to true, then the "Files"
+field is used in place of the "Checksums-Md5" field. By default the option
+is false.
+
+=cut
+
+sub add_from_control {
+    my ($self, $control, %opts) = @_;
+    $opts{use_files_for_md5} = 0 unless exists $opts{use_files_for_md5};
+    foreach my $alg (checksums_get_list()) {
+        my $key = "Checksums-$alg";
+        $key = 'Files' if ($opts{use_files_for_md5} and $alg eq 'md5');
+        if (exists $control->{$key}) {
+            $self->add_from_string($alg, $control->{$key});
+        }
+    }
+}
+
+=item @files = $ck->get_files()
+
+Return the list of files whose checksums are stored in the object.
+
+=cut
+
+sub get_files {
+    my ($self) = @_;
+    return @{$self->{files}};
+}
+
+=item $bool = $ck->has_file($file)
+
+Return true if we have checksums for the given file. Returns false
+otherwise.
+
+=cut
+
+sub has_file {
+    my ($self, $file) = @_;
+    return exists $self->{size}{$file};
+}
+
+=item $ck->remove_file($file)
+
+Remove all checksums of the given file.
+
+=cut
+
+sub remove_file {
+    my ($self, $file) = @_;
+    return unless $self->has_file($file);
+    delete $self->{checksums}{$file};
+    delete $self->{size}{$file};
+    @{$self->{files}} = grep { $_ ne $file } $self->get_files();
+}
+
+=item $checksum = $ck->get_checksum($file, $alg)
+
+Return the checksum of type $alg for the requested $file. This will not
+compute the checksum but only return the checksum stored in the object, if
+any.
+
+If $alg is not defined, it returns a reference to a hash: keys are
+the checksum algorithms and values are the checksums themselves. The
+hash returned must not be modified, it's internal to the object.
+
+=cut
+
+sub get_checksum {
+    my ($self, $file, $alg) = @_;
+    $alg = lc($alg) if defined $alg;
+    if (exists $self->{checksums}{$file}) {
+        return $self->{checksums}{$file} unless defined $alg;
+        return $self->{checksums}{$file}{$alg};
+    }
+    return;
+}
+
+=item $size = $ck->get_size($file)
+
+Return the size of the requested file if it's available in the object.
+
+=cut
+
+sub get_size {
+    my ($self, $file) = @_;
+    return $self->{size}{$file};
+}
+
+=item $ck->export_to_string($alg, %opts)
+
+Return a multi-line string containing the checksums of type $alg. The
+string can be stored as-is in a Checksum-* field of a Dpkg::Control
+object.
+
+=cut
+
+sub export_to_string {
+    my ($self, $alg, %opts) = @_;
+    my $res = '';
+    foreach my $file ($self->get_files()) {
+        my $sum = $self->get_checksum($file, $alg);
+        my $size = $self->get_size($file);
+        next unless defined $sum and defined $size;
+        $res .= "\n$sum $size $file";
+    }
+    return $res;
+}
+
+=item $ck->export_to_control($control, %opts)
+
+Export the checksums in the Checksums-* fields of the Dpkg::Control
+$control object.
+
+=cut
+
+sub export_to_control {
+    my ($self, $control, %opts) = @_;
+    $opts{use_files_for_md5} = 0 unless exists $opts{use_files_for_md5};
+    foreach my $alg (checksums_get_list()) {
+        my $key = "Checksums-$alg";
+        $key = 'Files' if ($opts{use_files_for_md5} and $alg eq 'md5');
+        $control->{$key} = $self->export_to_string($alg, %opts);
+    }
+}
+
+=back
+
+=head1 AUTHOR
+
+Raphaël Hertzog <hertzog@debian.org>.
+
+=cut
+
+1;