[buildd-tools-devel] Bug#620112: Generate binNMU changelogs deterministically for multiarch support

[Anders Kaseorg]

Package: sbuild
Version: 0.60.1-1
Tags: patch

According to https://wiki.ubuntu.com/MultiarchSpec#Binary%20NMUs , 
although a Multi-Arch: same package may not be binNMU’d on individual 
architectures, it should be possible to schedule a binNMU on all 
architectures at once, and have the resulting packages remain 
co-installable.  However, this does not quite work right now for a silly 
reason: sbuild generates a different timestamp for the binNMU changelog 
entry in each build, and the differing changelog.gz files break 
co-installability.

This fixes the problem by generating the timestamp in a deterministic way: 
we just copy the timestamp from the previous changelog entry.  (Since the 
source has not changed since that time, it seems like as good a time as 
any to write into the changelog.)

Certain automated backport setups that use --append-to-version are also 
affected by this issue and require this fix as well.

-- 8< --
From: Anders Kaseorg <andersk at mit.edu>
Subject: [PATCH 1/2] hack-binNMU: Use dpkg-parsechangelog

Signed-off-by: Anders Kaseorg <andersk at mit.edu>
---
 lib/Sbuild/Build.pm |   27 ++++++++++++++++++++-------
 1 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/lib/Sbuild/Build.pm b/lib/Sbuild/Build.pm
index 93032a9..9121c4e 100644
--- a/lib/Sbuild/Build.pm
+++ b/lib/Sbuild/Build.pm
@@ -794,13 +794,26 @@ sub build {
 	$self->log_subsubsection("Hack binNMU version");
 	$self->set('Pkg Fail Stage', "hack-binNMU");
 	if (open( F, "<$dscdir/debian/changelog" )) {
-	    my($firstline, $text);
-	    $firstline = "";
-	    $firstline = <F> while $firstline =~ /^$/;
-	    { local($/); undef $/; $text = <F>; }
+	    my $text = do { local $/; <F> };
 	    close( F );
-	    $firstline =~ /^(\S+)\s+\((\S+)\)\s+([^;]+)\s*;\s*urgency=(\S+)\s*$/;
-	    my ($name, $version, $dists, $urgent) = ($1, $2, $3, $4);
+
+	    my $pipe = $self->get('Session')->pipe_command(
+		{ COMMAND => [$Sbuild::Sysconfig::programs{'DPKG_PARSECHANGELOG'}],
+		  USER => $self->get_conf('USERNAME'),
+		  PRIORITY => 0,
+		  DIR => $self->get('Session')->strip_chroot_path($dscdir) });
+	    my $clog = do { local $/; <$pipe> };
+	    close($pipe);
+	    if ($?) {
+		$self->log("FAILED [dpkg-parsechangelog died]\n");
+		return 0;
+	    }
+
+	    my ($name) = $clog =~ /^Source:\s*(.*)$/m;
+	    my ($version) = $clog =~ /^Version:\s*(.*)$/m;
+	    my ($dists) = $clog =~ /^Distribution:\s*(.*)$/m;
+	    my ($urgency) = $clog =~ /^Urgency:\s*(.*)$/m;
+
 	    my $NMUversion = $self->get('Version');
 	    chomp( my $date = `date -R` );
 	    if (!open( F, ">$dscdir/debian/changelog" )) {
@@ -822,7 +835,7 @@ sub build {
 	    print F "\n";
 
 	    print F " -- " . $self->get_conf('MAINTAINER_NAME') . "  $date\n\n";
-	    print F $firstline, $text;
+	    print F $text;
 	    close( F );
 	    $self->log("*** Created changelog entry for bin-NMU version $NMUversion\n");
 	}
-- 
1.7.4.2


From: Anders Kaseorg <andersk at mit.edu>
Subject: [PATCH 2/2] hack-binNMU: Copy the date from the previous changelog

When a Multi-Arch: same package is simultaneously binNMU’d on all
architectures, a deterministic changelog.gz is necessary to avoid
breaking co-installability.

The same issue affected automated backport setups that use
--append-to-version.

Signed-off-by: Anders Kaseorg <andersk at mit.edu>
---
 lib/Sbuild/Build.pm |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/lib/Sbuild/Build.pm b/lib/Sbuild/Build.pm
index 9121c4e..0a68450 100644
--- a/lib/Sbuild/Build.pm
+++ b/lib/Sbuild/Build.pm
@@ -813,9 +813,9 @@ sub build {
 	    my ($version) = $clog =~ /^Version:\s*(.*)$/m;
 	    my ($dists) = $clog =~ /^Distribution:\s*(.*)$/m;
 	    my ($urgency) = $clog =~ /^Urgency:\s*(.*)$/m;
+	    my ($date) = $clog =~ /^Date:\s*(.*)$/m;
 
 	    my $NMUversion = $self->get('Version');
-	    chomp( my $date = `date -R` );
 	    if (!open( F, ">$dscdir/debian/changelog" )) {
 		$self->log("Can't open debian/changelog for binNMU hack: $!\n");
 		return 0;
-- 
1.7.4.2