clutter-offscreen-effect: Disable if no texture

If texture allocation fails (e.g. on an old GPU with size limit 2048)
then `update_fbo` would return `FALSE` but leaves `priv->offscreen`
as non-NULL. So the next paint will try to use the offscreen with a
`NULL` texture and crashes. The solution is simply to ensure that
`priv->offscreen` is NULL if there is no `priv->texture`, so the default
(non-offscreen) paint path gets used instead.

Bug reported and fix provided by Gert van de Kraats.

Origin: https://gitlab.gnome.org/GNOME/mutter/commit/f31cf0c3e
Bug-Ubuntu: https://launchpad.net/bugs/1795774
Applied-upstream: 3.30.3

Gbp-Pq: Name clutter-offscreen-effect-Disable-if-no-texture.patch

diff --git a/clutter/clutter/clutter-offscreen-effect.c b/clutter/clutter/clutter-offscreen-effect.c
index 743020eb2c458ff126cd6cdeb6b37956e6c77339..a26275e5f00362c95584a930c8e1426bce6389dd 100644 (file)
--- a/clutter/clutter/clutter-offscreen-effect.c
+++ b/clutter/clutter/clutter-offscreen-effect.c
@@ -180,6 +180,12 @@ update_fbo (ClutterEffect *effect, int fbo_width, int fbo_height)
       priv->texture = NULL;
     }
 
+  if (priv->offscreen != NULL)
+    {
+      cogl_handle_unref (priv->offscreen);
+      priv->offscreen = NULL;
+    }
+
   priv->texture =
     clutter_offscreen_effect_create_texture (self, fbo_width, fbo_height);
   if (priv->texture == NULL)
@@ -190,9 +196,6 @@ update_fbo (ClutterEffect *effect, int fbo_width, int fbo_height)
   priv->fbo_width = fbo_width;
   priv->fbo_height = fbo_height;
 
-  if (priv->offscreen != NULL)
-    cogl_handle_unref (priv->offscreen);
-
   priv->offscreen = cogl_offscreen_new_to_texture (priv->texture);
   if (priv->offscreen == NULL)
     {