Merge lp:~jamesodhunt/ubuntu/quantal/debconf/bug-1060249 into lp:ubuntu/raring/debconf

[James Hunt]

* Debconf/Frontend/Gnome.pm:init(): Only 'use Gtk2;' once it has been
  proven to be safe to avoid rogue Perl module behaviour from crashing
  debconf (#LP: 1060249).

[Colin Watson (cjwatson)]

This has been merged upstream. I'm working on a different problem before preparing a release, and then I think it will be fine to just merge that into raring.

=== modified file 'Debconf/FrontEnd/Gnome.pm'
--- Debconf/FrontEnd/Gnome.pm	2011-06-23 06:52:13 +0000
+++ Debconf/FrontEnd/Gnome.pm	2012-11-26 20:29:20 +0000
@@ -14,13 +14,6 @@
 use Debconf::Encoding qw(to_Unicode);
 use base qw{Debconf::FrontEnd};
 
-# Catch this so as not to confuse the poor users if Gtk or Gnome are not
-# installed.
-eval q{
-	use Gtk2;
-};
-die "Unable to load Gtk -- is libgtk2-perl installed?\n" if $@;
-
 =head1 DESCRIPTION
 
 This FrontEnd is a Gnome UI for Debconf.
@@ -121,11 +114,35 @@
 		}
 	}
 	else {
+		# Catch scenario where Gtk/Gnome are not installed.
+		use Gtk2;
+
 		@ARGV=@ARGV_for_gnome; # temporary change at first
 		Gtk2->init;
+
+		# Create a window, but don't show it.
+		#
+		# This has the effect of exercising gtk a bit in an
+		# attempt to force an error either in the gtk bindings
+		# themselves, but hopefully also in
+		# gtk/glib/gsettings/etc. There is no guarantee that
+		# this alone will provoke an error, but it's a
+		# relatively safe and reasonable operation to perform
+		# and further reduces the chance of the parent debconf
+		# process ending up in an unrecoverable state.
+		my $window = Gtk2::Window->new('toplevel');
+
 		exit(0); # success
 	}
 	
+	# Only load Gtk after the child has successfully proved it can do
+	# the same. This avoids the problem where a module calls into a
+	# native library and causes the perl interpreter to crash. When
+	# we get to here, we know that the child didn't crash, so it
+	# should be safe for us to attempt it.
+	eval q{use Gtk2;};
+	die "Unable to load Gtk -- is libgtk2-perl installed?\n" if $@;
+
 	my @gnome_sucks=@ARGV;
 	@ARGV=@ARGV_for_gnome;
 	Gtk2->init;
 
=== modified file 'debian/changelog'
--- debian/changelog	2012-08-16 17:37:10 +0000
+++ debian/changelog	2012-11-26 20:29:20 +0000
@@ -1,3 +1,11 @@
+debconf (1.5.46ubuntu2) UNRELEASED; urgency=low
+
+  * Debconf/Frontend/Gnome.pm:init(): Only 'use Gtk2;' once it has been
+    proven to be safe to avoid rogue Perl module behaviour from crashing
+    debconf (#LP: 1060249).
+
+ -- James Hunt <[e-mail]>  Wed, 17 Oct 2012 13:46:47 +0100
+
 debconf (1.5.46ubuntu1) quantal; urgency=low
 
   * Resynchronise with Debian.  Remaining changes: