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=head1 NAME

Dpkg::Checksums - generate and manipulate file checksums

=head1 DESCRIPTION

This module provides a class that can generate and manipulate
various file checksums as well as some methods to query information
about supported checksums.

=cut

=head1 FUNCTIONS

=over 4

=cut

=item @list = checksums_get_list()

Returns the list of supported checksums algorithms.

=cut

=item $bool = checksums_is_supported($alg)

Returns a boolean indicating whether the given checksum algorithm is
supported. The checksum algorithm is case-insensitive.

=cut

=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 "name" (returns the name of the digest
algorithm), "regex" for the regular expression describing the common
string representation of the checksum, and "strong" for a boolean describing
whether the checksum algorithm is considered cryptographically strong.

=cut

=head1 METHODS

=over 4

=item $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

=item $ck->reset()

Forget about all checksums stored. The object is again in the same state
as if it was newly created.

=cut

=item $ck->add_from_file($filename, %opts)

Add or verify 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, and the caller did not request that it be
updated with the boolean "update" option.

=cut

=item $ck->add_from_string($alg, $value, %opts)

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, and the caller did not request that it be updated with
the boolean "update" option.

=cut

=item $ck->add_from_control($control, %opts)

Read checksums from Checksums-* fields stored in the L<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

=item @files = $ck->get_files()

Return the list of files whose checksums are stored in the object.

=cut

=item $bool = $ck->has_file($file)

Return true if we have checksums for the given file. Returns false
otherwise.

=cut

=item $ck->remove_file($file)

Remove all checksums of the given file.

=cut

=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

=item $size = $ck->get_size($file)

Return the size of the requested file if it's available in the object.

=cut

=item $bool = $ck->has_strong_checksums($file)

Return a boolean on whether the file has a strong checksum.

=cut

=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 L<Dpkg::Control>
object.

=cut

=item $ck->export_to_control($control, %opts)

Export the checksums in the Checksums-* fields of the L<Dpkg::Control>
$control object.

=cut

=head1 CHANGES

=head2 Version 1.04 (dpkg 1.20.0)

Remove warning: For obsolete property 'program'.

=head2 Version 1.03 (dpkg 1.18.5)

New property: Add new 'strong' property.

New member: $ck->has_strong_checksums().

=head2 Version 1.02 (dpkg 1.18.0)

Obsolete property: Getting the 'program' checksum property will warn and
return undef, the Digest module is used internally now.

New property: Add new 'name' property with the name of the Digest algorithm
to use.

=head2 Version 1.01 (dpkg 1.17.6)

New argument: Accept an options argument in $ck->export_to_string().

New option: Accept new option 'update' in $ck->add_from_file() and
$ck->add_from_control().

=head2 Version 1.00 (dpkg 1.15.6)

Mark the module as public.

=cut