[mutter/wayland] wayland-surface: Don't crash if a client destroys a buffer in use

[Jasper St. Pierre <jstpierre src gnome org>]

commit 3e98ffaf9958366b584b360ac12bbc03cd070c07
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Mon Feb 3 18:36:46 2014 -0500

    wayland-surface: Don't crash if a client destroys a buffer in use
    
    This is considered "undefined" by upstream. Right now GTK+ does this
    a lot, so we shouldn't crash. Let's make them crash instead and send
    them an error instead.

 src/wayland/meta-wayland-surface.c |   23 +++++++++++++++++++++--
 src/wayland/meta-wayland-surface.h |    4 +++-
 2 files changed, 24 insertions(+), 3 deletions(-)
---
diff --git a/src/wayland/meta-wayland-surface.c b/src/wayland/meta-wayland-surface.c
index 0dca23e..909d624 100644
--- a/src/wayland/meta-wayland-surface.c
+++ b/src/wayland/meta-wayland-surface.c
@@ -72,6 +72,17 @@ typedef struct
 } MetaWaylandSubsurfacePlacementOp;
 
 static void
+surface_handle_buffer_destroy (struct wl_listener *listener, void *data)
+{
+  MetaWaylandSurface *surface = wl_container_of (listener, surface, buffer_destroy_listener);
+
+  wl_resource_post_error (surface->resource, WL_DISPLAY_ERROR_INVALID_OBJECT,
+                          "Destroyed buffer while it was attached to the surface");
+  surface->buffer = NULL;
+  wl_list_remove (&surface->buffer_destroy_listener.link);
+}
+
+static void
 surface_set_buffer (MetaWaylandSurface *surface,
                     MetaWaylandBuffer  *buffer)
 {
@@ -79,12 +90,18 @@ surface_set_buffer (MetaWaylandSurface *surface,
     return;
 
   if (surface->buffer)
-    meta_wayland_buffer_unref (surface->buffer);
+    {
+      meta_wayland_buffer_unref (surface->buffer);
+      wl_list_remove (&surface->buffer_destroy_listener.link);
+    }
 
   surface->buffer = buffer;
 
   if (surface->buffer)
-    meta_wayland_buffer_ref (surface->buffer);
+    {
+      meta_wayland_buffer_ref (surface->buffer);
+      wl_signal_add (&surface->buffer->destroy_signal, &surface->buffer_destroy_listener);
+    }
 }
 
 static void
@@ -621,6 +638,8 @@ meta_wayland_surface_create (MetaWaylandCompositor *compositor,
 
   double_buffered_state_init (&surface->pending);
 
+  surface->buffer_destroy_listener.notify = surface_handle_buffer_destroy;
+
   surface->surface_actor = g_object_ref_sink (meta_surface_actor_new ());
   return surface;
 }
diff --git a/src/wayland/meta-wayland-surface.h b/src/wayland/meta-wayland-surface.h
index 129ce8a..3e1b297 100644
--- a/src/wayland/meta-wayland-surface.h
+++ b/src/wayland/meta-wayland-surface.h
@@ -71,7 +71,6 @@ struct _MetaWaylandSurface
 {
   struct wl_resource *resource;
   MetaWaylandCompositor *compositor;
-  MetaWaylandBuffer *buffer;
   MetaSurfaceActor *surface_actor;
   MetaWindow *window;
   MetaWaylandSurfaceExtension xdg_surface;
@@ -79,6 +78,9 @@ struct _MetaWaylandSurface
   MetaWaylandSurfaceExtension gtk_surface;
   MetaWaylandSurfaceExtension subsurface;
 
+  MetaWaylandBuffer *buffer;
+  struct wl_listener buffer_destroy_listener;
+
   GList *subsurfaces;
 
   struct {