Package: strip-nondeterminism
Version: 0.003-1
Severity: wishlist
Tags: patch
User: reproducible-builds@lists.alioth.debian.org
Usertags: toolchain timestamps
X-Debbugs-Cc: reproducible-builds@lists.alioth.debian.org
Hi,
A patch attached with initial support for overriding timestamps
in PNG files.
Possible limitations:
* Other tEXt free-form formats; eg. "date:create" and "date:modify"
are ImageMagick specific, apparently
* Timestamps in compressed or "international" text chunks (zTXt/iTXt)
Regards,
--
,''`.
: :' : Chris Lamb
`. `'` la...@debian.org / chris-lamb.co.uk
`-
From 79a50129221d10bccee38c5e4d8cd6c59e69fd02 Mon Sep 17 00:00:00 2001
From: Chris Lamb <la...@debian.org>
Date: Wed, 11 Feb 2015 12:24:49 +0000
Subject: [PATCH] Add initial support for PNG
---
lib/File/StripNondeterminism.pm | 6 +++
lib/File/StripNondeterminism/handlers/png.pm | 81 ++++++++++++++++++++++++++++
2 files changed, 87 insertions(+)
create mode 100644 lib/File/StripNondeterminism/handlers/png.pm
diff --git a/lib/File/StripNondeterminism.pm b/lib/File/StripNondeterminism.pm
index 8f4d4b7..8d17640 100644
--- a/lib/File/StripNondeterminism.pm
+++ b/lib/File/StripNondeterminism.pm
@@ -27,6 +27,7 @@ use File::StripNondeterminism::handlers::jar;
use File::StripNondeterminism::handlers::javadoc;
use File::StripNondeterminism::handlers::pe;
use File::StripNondeterminism::handlers::pearregistry;
+use File::StripNondeterminism::handlers::png;
use File::StripNondeterminism::handlers::javaproperties;
use File::StripNondeterminism::handlers::zip;
@@ -73,6 +74,10 @@ sub get_normalizer_for_file {
if (m/\.(exe|dll|cpl|ocx|sys|scr|drv|efi|fon)/ && _get_file_type($_) =~ m/PE32.? executable/) {
return \&File::StripNondeterminism::handlers::pe::normalize;
}
+ # PNG
+ if (m/\.png$/ && _get_file_type($_) =~ m/PNG image data/) {
+ return \&File::StripNondeterminism::handlers::png::normalize;
+ }
# pom.properties, version.properties
if (m/(pom|version)\.properties$/ && File::StripNondeterminism::handlers::javaproperties::is_java_properties_file($_)) {
return \&File::StripNondeterminism::handlers::javaproperties::normalize;
@@ -92,6 +97,7 @@ sub get_normalizer_by_name {
return \&File::StripNondeterminism::handlers::javadoc::normalize if $_ eq 'javadoc';
return \&File::StripNondeterminism::handlers::pe::normalize if $_ eq 'pe';
return \&File::StripNondeterminism::handlers::pearregistry::normalize if $_ eq 'pearregistry';
+ return \&File::StripNondeterminism::handlers::png::normalize if $_ eq 'png';
return \&File::StripNondeterminism::handlers::javaproperties::normalize if $_ eq 'javaproperties';
return \&File::StripNondeterminism::handlers::zip::normalize if $_ eq 'zip';
return undef;
diff --git a/lib/File/StripNondeterminism/handlers/png.pm b/lib/File/StripNondeterminism/handlers/png.pm
new file mode 100644
index 0000000..2b300b3
--- /dev/null
+++ b/lib/File/StripNondeterminism/handlers/png.pm
@@ -0,0 +1,81 @@
+#
+# Copyright 2015 Chris Lamb <la...@debian.org>
+#
+# This file is part of strip-nondeterminism.
+#
+# strip-nondeterminism is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# strip-nondeterminism is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with strip-nondeterminism. If not, see <http://www.gnu.org/licenses/>.
+#
+package File::StripNondeterminism::handlers::png;
+
+use strict;
+use warnings;
+
+use Fcntl qw/:seek/;
+use POSIX qw/strftime/;
+use Digest::CRC qw/crc32/;
+
+sub normalize {
+ my ($filename) = @_;
+
+ my $buffer = "";
+ my $canonical_time = $File::StripNondeterminism::canonical_time // 0;
+
+ open PNG, '+<', $filename
+ || die "Could not open '$filename' for reading: $!";
+
+ # Check magic
+ read PNG, $buffer, 8;
+ $buffer eq "\x89PNG\r\n\x1a\n"
+ || die "'$filename' does not appear to be a PNG file";
+
+ while (1) {
+ read PNG, $buffer, 8;
+ last if length($buffer) < 8;
+
+ # Parse chunk header
+ my ($len, $type) = unpack('Na4', $buffer);
+
+ if ($type eq "tIME") {
+ my $val = pack('nC5', $canonical_time);
+ print PNG $val;
+ print PNG pack('N', crc32($type . $val));
+ } elsif ($type eq "tEXt") {
+ # Read entire field
+ read PNG, $buffer, $len + 4;
+
+ # Split contents by null byte
+ if (my ($tag) = $buffer =~ /^(date:[^\0]+)/) {
+ # Join with new timestamp
+ my $val = "$tag\0". strftime("%Y-%m-%dT%H:%M:%S%z",
+ gmtime($canonical_time));
+
+ # +0100 (%z) -> +01:00
+ $val =~ s/(?<=[+-]\d\d)(?=\d\d$)/:/;
+
+ # Seek backwards as we already read the field
+ seek PNG, -($len + 4), SEEK_CUR;
+
+ print PNG $val;
+ print PNG pack('N', crc32($type . $val));
+ }
+ } else {
+ # Skip chunk data and CRC
+ seek PNG, $len + 4, SEEK_CUR;
+ }
+ }
+
+ close PNG;
+}
+
+1;
--
2.1.0
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