Commit f40f5550 authored by Chris Lamb's avatar Chris Lamb 👀
Browse files

Workaround Archive::Zip's incorrect handling of the localExtraField field by... 

Workaround Archive::Zip's incorrect handling of the localExtraField field by monkey-patching the accessor methods to always return normalised values. This fixes the normalisation of Unix ownership (uid/gid) within .zip archives, .epub files, etc. (Closes: #858431, #4)
parent b164403e

Makefile.PL

+1 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ WriteMakefile( 
		'Archive::Cpio'	=> 0, # required to pass tests

		'Archive::Zip'	=> 0,

		'Getopt::Long'	=> 0,

		'Monkey::Patch'	=> 0,

	},

	LICENSE		=> "gpl",

	dist		=> { COMPRESS => 'gzip -9nf', SUFFIX => 'gz', },

lib/File/StripNondeterminism/handlers/zip.pm

+26 −5
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ use warnings; 
use File::Temp;

use File::StripNondeterminism;

use Archive::Zip qw/:CONSTANTS :ERROR_CODES/;

use Monkey::Patch qw/patch_class/;



# A magic number from Archive::Zip for the earliest timestamp that

# can be represented by a Zip file.  From the Archive::Zip source:
@@ -217,14 +218,34 @@ sub normalize { 
				? oct(755)

				: oct(644));

		}

		foreach my $x (qw(cdExtraField localExtraField)) {

			my $result = normalize_extra_fields($canonical_time, $member->$x);

			return 0 unless defined $result;

			$member->$x($result);

		}

	}

	my $old_perms = (stat($zip_filename))[2] & oct(7777);



	# Archive::Zip::Member does not handle the localExtraField field (used for

	# uid/gids) correctly or consistently.

	#

	# It does not populate localExtraField in the class upon initial reading of

	# the file whilst it does for cdExtraField. One can workaround this

	# manually with calls to _seekToLocalHeader and _readLocalFileHeader but

	# upon writing to a file back to the disk Archive::Zip will ignore any

	# stored value of localExtraField (!) and reload it again from the existing

	# file handle in/around rewindData.

	#

	# We therefore monkey-patch the accessor methods of the Member class to

	# ensure that normalised values are used in this final save.

	#

	# <https://salsa.debian.org/reproducible-builds/strip-nondeterminism/issues/4>

	my @patches = map {

		patch_class('Archive::Zip::Member', $_, sub {

			my $fn = shift;

			my $result = $fn->(@_);

			return defined($result) ?

				normalize_extra_fields($canonical_time, $result) : $result;

		});

	} qw(cdExtraField localExtraField);



	return 0 unless $zip->overwrite() == AZ_OK;

	undef @patches; # Remove our monkey patches

	chmod($old_perms, $zip_filename);

	return 1;

}