[mutter] wayland: Don't access the cursor wl_buffer when updating the sprite

[Jonas Ådahl <jadahl src gnome org>]

commit 96927b34154d7a234eaaf2702027034b6c0395dd
Author: Jonas Ådahl <jadahl gmail com>
Date:   Wed Mar 2 14:26:16 2016 +0800

    wayland: Don't access the cursor wl_buffer when updating the sprite
    
    We may have released the wl_buffer already when doing this, which means
    we should not try to access the wl_buffer content.
    
    Regarding the cursor texture this is not an issue since we can just use
    the texture created in apply_pending_state().
    
    The hw cursor however will only be realized if the surface is already
    using the the buffer (surface->using_buffer == true). This will, at the
    moment, effectively disable hardware cursors for SHM buffers.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=762828

 src/wayland/meta-wayland-pointer.c |   29 +++++++++++++----------------
 1 files changed, 13 insertions(+), 16 deletions(-)
---
diff --git a/src/wayland/meta-wayland-pointer.c b/src/wayland/meta-wayland-pointer.c
index 4fb32bb..89dd2cd 100644
--- a/src/wayland/meta-wayland-pointer.c
+++ b/src/wayland/meta-wayland-pointer.c
@@ -967,28 +967,25 @@ update_cursor_sprite_texture (MetaWaylandSurface *surface)
   MetaWaylandSurfaceRoleCursor *cursor_role =
     META_WAYLAND_SURFACE_ROLE_CURSOR (surface->role);
   MetaCursorSprite *cursor_sprite = cursor_role->cursor_sprite;
-  ClutterBackend *clutter_backend = clutter_get_default_backend ();
-  CoglContext *cogl_context =
-    clutter_backend_get_cogl_context (clutter_backend);
-  CoglTexture *texture;
+
+  g_return_if_fail (!surface->buffer || surface->buffer->texture);
 
   if (surface->buffer)
     {
-      struct wl_resource *buffer;
-
-      buffer = surface->buffer->resource;
-      texture = cogl_wayland_texture_2d_new_from_buffer (cogl_context,
-                                                         buffer,
-                                                         NULL);
-
       meta_cursor_sprite_set_texture (cursor_sprite,
-                                      texture,
+                                      surface->buffer->texture,
                                       cursor_role->hot_x * surface->scale,
                                       cursor_role->hot_y * surface->scale);
-      meta_cursor_renderer_realize_cursor_from_wl_buffer (cursor_renderer,
-                                                          cursor_sprite,
-                                                          buffer);
-      cogl_object_unref (texture);
+
+      if (surface->using_buffer)
+        {
+          struct wl_resource *buffer;
+
+          buffer = surface->buffer->resource;
+          meta_cursor_renderer_realize_cursor_from_wl_buffer (cursor_renderer,
+                                                              cursor_sprite,
+                                                              buffer);
+        }
     }
   else
     {