From 52dfa038b9e0c106aa3f9f08abeb7f53e72a762a Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue, 1 May 2012 15:06:46 +0100
Subject: [PATCH] snapshot: Avoid triggering assertion for grabbing the target
 during destroy

If the source wins the race to acquire the original surface as it is
being destroyed, it triggers an assertion.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 src/cairo-surface-inline.h          | 8 ++++++++
 src/cairo-surface-snapshot-inline.h | 3 ++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/cairo-surface-inline.h b/src/cairo-surface-inline.h
index 1b257d5c3..27ea8f0ec 100644
--- a/src/cairo-surface-inline.h
+++ b/src/cairo-surface-inline.h
@@ -49,4 +49,12 @@ _cairo_surface_flush (cairo_surface_t *surface)
     return status;
 }
 
+static inline cairo_surface_t *
+_cairo_surface_reference (cairo_surface_t *surface)
+{
+    if (!CAIRO_REFERENCE_COUNT_IS_INVALID (&surface->ref_count))
+	_cairo_reference_count_inc (&surface->ref_count);
+    return surface;
+}
+
 #endif /* CAIRO_SURFACE_INLINE_H */
diff --git a/src/cairo-surface-snapshot-inline.h b/src/cairo-surface-snapshot-inline.h
index 7c15b81a7..bf89c772b 100644
--- a/src/cairo-surface-snapshot-inline.h
+++ b/src/cairo-surface-snapshot-inline.h
@@ -37,6 +37,7 @@
 #define CAIRO_SURFACE_SNAPSHOT_INLINE_H
 
 #include "cairo-surface-snapshot-private.h"
+#include "cairo-surface-inline.h"
 
 static inline cairo_bool_t
 _cairo_surface_snapshot_is_reused (cairo_surface_t *surface)
@@ -51,7 +52,7 @@ _cairo_surface_snapshot_get_target (cairo_surface_t *surface)
     cairo_surface_t *target;
 
     CAIRO_MUTEX_LOCK (snapshot->mutex);
-    target = cairo_surface_reference (snapshot->target);
+    target = _cairo_surface_reference (snapshot->target);
     CAIRO_MUTEX_UNLOCK (snapshot->mutex);
 
     return target;