From 2229cafc3833a017b3a107b4f6b207f0a95908f5 Mon Sep 17 00:00:00 2001
From: Emmanuele Bassi <ebassi@linux.intel.com>
Date: Mon, 15 Feb 2010 12:04:50 +0000
Subject: [PATCH] stage: Add sanity checks for get_pending_swaps()

The master clock might have a Stage during its destruction phase,
without a StageWindow attached to it. If this happens and we try
to dereference the StageWindow to get its class and call a virtual
function we might experience some slight turbulence and... then...
explode.

http://bugzilla.openedhand.com/show_bug.cgi?id=1987
---
 clutter/clutter-master-clock.c | 21 +++++++++++++--------
 clutter/clutter-stage.c        | 10 +++++++++-
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/clutter/clutter-master-clock.c b/clutter/clutter-master-clock.c
index 1e7efcf2d..8b4a42f95 100644
--- a/clutter/clutter-master-clock.c
+++ b/clutter/clutter-master-clock.c
@@ -129,11 +129,14 @@ master_clock_is_running (ClutterMasterClock *master_clock)
   /* If all of the stages are busy waiting for a swap-buffers to complete
    * then we stop the master clock... */
   for (l = stages; l != NULL; l = l->next)
-    if (_clutter_stage_get_pending_swaps (l->data) == 0)
-      {
-        stage_free = TRUE;
-        break;
-      }
+    {
+      if (_clutter_stage_get_pending_swaps (l->data) == 0)
+        {
+          stage_free = TRUE;
+          break;
+        }
+    }
+
   if (!stage_free)
     return FALSE;
 
@@ -141,9 +144,11 @@ master_clock_is_running (ClutterMasterClock *master_clock)
     return TRUE;
 
   for (l = stages; l; l = l->next)
-    if (_clutter_stage_has_queued_events (l->data) ||
-        _clutter_stage_needs_update (l->data))
-      return TRUE;
+    {
+      if (_clutter_stage_has_queued_events (l->data) ||
+          _clutter_stage_needs_update (l->data))
+        return TRUE;
+    }
 
   if (master_clock->ensure_next_iteration)
     {
diff --git a/clutter/clutter-stage.c b/clutter/clutter-stage.c
index 738478c5b..00fb26c1a 100644
--- a/clutter/clutter-stage.c
+++ b/clutter/clutter-stage.c
@@ -2393,7 +2393,15 @@ clutter_stage_get_minimum_size (ClutterStage *stage,
 int
 _clutter_stage_get_pending_swaps (ClutterStage *stage)
 {
-  ClutterStageWindow *stage_window = _clutter_stage_get_window (stage);
+  ClutterStageWindow *stage_window;
+
+  if (CLUTTER_PRIVATE_FLAGS (stage) & CLUTTER_ACTOR_IN_DESTRUCTION)
+    return 0;
+
+  stage_window = _clutter_stage_get_window (stage);
+  if (stage_window == NULL)
+    return 0;
+
   return _clutter_stage_window_get_pending_swaps (stage_window);
 }