[Reproducible-commits] [debhelper] 01/05: dh_builddeb: fix mtimes for reproducibility

[Mattia Rizzolo]

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mapreri-guest pushed a commit to branch pu/reproducible_builds
in repository debhelper.

commit e115d5b703c0e945d80a3b2a3c1470cc91ed6ad3
Author: Jérémy Bobbio <lunar at debian.org>
Date:   Fri Aug 29 03:46:09 2014 +0000

    dh_builddeb: fix mtimes for reproducibility
    
    To enable reproducible builds, file modification times written in binary
    packages should be the same accross multiple builds of the same source
    package. dh_builddeb will now change the modification time of any file that
    has been created later than the time of the latest debian/changelog
    entry to the time of the latest debian/changelog entry.
    
    See https://wiki.debian.org/ReproducibleBuilds for more information on
    reproducible builds in Debian.
    
    Closes: #759886
---
 Debian/Debhelper/Dh_Lib.pm |  4 +++-
 dh_builddeb                | 27 +++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/Debian/Debhelper/Dh_Lib.pm b/Debian/Debhelper/Dh_Lib.pm
index 53c570f..e23856b 100644
--- a/Debian/Debhelper/Dh_Lib.pm
+++ b/Debian/Debhelper/Dh_Lib.pm
@@ -543,7 +543,8 @@ sub pkgfilename {
 }
 
 # Returns 1 if the package is a native debian package, null otherwise.
-# As a side effect, sets $dh{VERSION} to the version of this package.
+# As a side effect, sets $dh{VERSION} to the version of this package,
+# and $dh{DATE} to the date of the latest changelog entry.
 {
 	# Caches return code so it only needs to run dpkg-parsechangelog once.
 	my %isnative_cache;
@@ -565,6 +566,7 @@ sub pkgfilename {
 		if (! defined $dh{VERSION}) {
 			error("changelog parse failure");
 		}
+		($dh{DATE})=$version=~m/Date:\s*(.*)/m;
 
 		# Is this a native Debian package?
 		if ($dh{VERSION}=~m/.*-/) {
diff --git a/dh_builddeb b/dh_builddeb
index f314e5a..33592a9 100755
--- a/dh_builddeb
+++ b/dh_builddeb
@@ -23,6 +23,17 @@ and L<dh_gencontrol(1)> have prepared them.
 It supports building multiple binary packages in parallel, when enabled by
 DEB_BUILD_OPTIONS.
 
+Before building the package, it will reset the modification times of files and
+directories in package build directories to a state easily reproducible accross
+multiple builds.
+
+It will examine the modification time of all files in the package
+build directory. If the file is newer than the date of the latest
+debian/changelog entry, we assume the file is a result of a build, and its
+modification time will be set to the date of the latest debian/changelog entry.
+
+This removes unneeded variations accross builds of the same package.
+
 =head1 OPTIONS
 
 =over 4
@@ -121,6 +132,9 @@ sub build_and_rename_deb {
 }
 
 foreach my $package (@{$dh{DOPACKAGES}}) {
+	# XXX: not nice, we only run this for the side effect of getting $dh{DATE} set
+	isnative($package);
+
 	my $pid=fork();
 	if (! defined $pid) {
 		error("fork failed! $!");
@@ -145,6 +159,12 @@ foreach my $package (@{$dh{DOPACKAGES}}) {
 				foreach split(":", $ENV{DH_ALWAYS_EXCLUDE});
 		}
 	}
+
+	my $find_options='';
+	if (defined($dh{EXCLUDE_FIND}) && $dh{EXCLUDE_FIND} ne '') {
+		$find_options="! \\( $dh{EXCLUDE_FIND} \\)";
+	}
+
 	if ( -d $ddeb_tmpdir) {
 		my $ddeb_control = "${ddeb_tmpdir}/DEBIAN/control";
 		# Only build the ddeb if it has a control file.  People might
@@ -155,6 +175,9 @@ foreach my $package (@{$dh{DOPACKAGES}}) {
 			# the ddeb.
 			my @args = default_compressor_args(["-z1", "-Zxz", "-Sextreme"],
 											   @{$dh{U_PARAMS}});
+			complex_doit("find $ddeb_tmpdir -newermt '$dh{DATE}' $find_options -print0",
+					"2>/dev/null | xargs -0r touch --no-dereference --date='$dh{DATE}'");
+
 			doit("dpkg-deb", @args,
 				 "--build", $ddeb_tmpdir, $dh{DESTDIR});
 		} elsif (not is_udeb($package)) {
@@ -162,6 +185,10 @@ foreach my $package (@{$dh{DOPACKAGES}}) {
 			warning("Please use dh_gencontrol to avoid this issue");
 		}
 	}
+
+	complex_doit("find $tmp -newermt '$dh{DATE}' $find_options -print0",
+		"2>/dev/null | xargs -0r touch --no-dereference --date='$dh{DATE}'");
+
 	if (! is_udeb($package)) {
 		doit("dpkg-deb", @{$dh{U_PARAMS}}, "--build", $tmp, $dh{DESTDIR}.$dh{FILENAME});
 	}

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