Avoid race when using GConf and DBus with threads (bgo#692374)

GConf causes us to make indirect calls to libdbus from multiple threads,
resulting in crashes if threads are not initialized explictly. As a
workaround, we initialize dbus-glib for multithreading.

This fixes adds an optional build-time dependency on dbus-glib, and will
only be enabled if that dependency is satisfied.

Some distros have addressed this issue by patching the underlying
llibraries (gconf or gconf-sharp), so they don't have to enable that
fix. But it should not conflict with those patches, as
dbus_g_thread_init can be called multiple time, contrary to what the
API documentation says.

Signed-off-by: Bertrand Lorentz <bertrand.lorentz@gmail.com>

4 files changed, 28 insertions, 0 deletions

diff --git a/build/m4/banshee/gconf.m4 b/build/m4/banshee/gconf.m4
index 16239dbcd..fbf1ce679 100644
--- a/build/m4/banshee/gconf.m4
+++ b/build/m4/banshee/gconf.m4
@@ -9,4 +9,12 @@ AC_DEFUN([BANSHEE_CHECK_GCONF],
 	m4_pattern_allow([AM_GCONF_SOURCE_2])
 
 	AM_GCONF_SOURCE_2
+
+	# dbus-glib is needed for the workaround for bgo#692374
+	PKG_CHECK_MODULES(DBUS_GLIB, dbus-glib-1 >= 0.80, have_dbus_glib="yes", have_dbus_glib="no")
+	if test "x$have_dbus_glib" = "xyes"; then
+		AM_CONDITIONAL(HAVE_DBUS_GLIB, true)
+	else
+		AM_CONDITIONAL(HAVE_DBUS_GLIB, false)
+	fi
 ])
diff --git a/src/Core/Banshee.ThickClient/Banshee.Gui/GtkBaseClient.cs b/src/Core/Banshee.ThickClient/Banshee.Gui/GtkBaseClient.cs
index c5c567582..c3891c1a1 100644
--- a/src/Core/Banshee.ThickClient/Banshee.Gui/GtkBaseClient.cs
+++ b/src/Core/Banshee.ThickClient/Banshee.Gui/GtkBaseClient.cs
@@ -28,6 +28,7 @@
 
 using System;
 using System.IO;
+using System.Runtime.InteropServices;
 
 using Mono.Addins;
 
@@ -100,6 +101,9 @@ namespace Banshee.Gui
         {
         }
 
+        [DllImport ("libdbus-glib-1-2.dll")]
+        internal static extern void dbus_g_thread_init ();
+
         protected virtual void InitializeGtk ()
         {
             Log.Debug ("Initializing GTK");
@@ -107,6 +111,13 @@ namespace Banshee.Gui
             if (!GLib.Thread.Supported) {
                 GLib.Thread.Init ();
             }
+
+#if HAVE_DBUS_GLIB
+            // Using GConf from multiple threads causes crashes if multithreading is not initialized explictly in dbus
+            // This is a workaround for bgo#692374
+            dbus_g_thread_init ();
+#endif
+
             Gtk.Application.Init ();
 
             if (ApplicationContext.CommandLine.Contains ("debug-gtkrc")) {
diff --git a/src/Core/Banshee.ThickClient/Banshee.ThickClient.dll.config b/src/Core/Banshee.ThickClient/Banshee.ThickClient.dll.config
new file mode 100644
index 000000000..d69fdc85d
--- /dev/null
+++ b/src/Core/Banshee.ThickClient/Banshee.ThickClient.dll.config
@@ -0,0 +1,3 @@
+<configuration>
+  <dllmap dll="libdbus-glib-1-2.dll" target="libdbus-glib-1.so.2"/>
+</configuration>
diff --git a/src/Core/Banshee.ThickClient/Makefile.am b/src/Core/Banshee.ThickClient/Makefile.am
index 5eeaff2a5..bdcea43c4 100644
--- a/src/Core/Banshee.ThickClient/Makefile.am
+++ b/src/Core/Banshee.ThickClient/Makefile.am
@@ -3,6 +3,10 @@ TARGET = library
 ASSEMBLY_BUILD_FLAGS = -unsafe
 LINK = $(REF_BANSHEE_THICKCLIENT)
 
+if HAVE_DBUS_GLIB
+BUILD_DEFINES = "-define:HAVE_DBUS_GLIB"
+endif
+
 SOURCES =  \
 	Banshee.Addins.Gui/AddinView.cs \
 	Banshee.CairoGlyphs/BansheeLineLogo.cs \
@@ -174,3 +178,5 @@ RESOURCES =  \
 
 include $(top_srcdir)/build/build.mk
 
+EXTRA_DIST += Banshee.ThickClient.dll.config
+module_SCRIPTS += Banshee.ThickClient.dll.config