evas: Fix very unlikely crash in evas render

During a stress test of EFL a seemingly impossible crash happened, where
one of object's cow fields was NULL inside evas_object_was_visible.
Nothing in the code flow can possibly lead to this situation but
it still happened. For information, the object's delete_me flag was 2 in
evas_object_is_active() called from _evas_render_phase1_object_process().
So let's add a small safety check for crash prevention.

Differential Revision: https://phab.enlightenment.org/D4608

diff --git a/src/lib/evas/include/evas_inline.x b/src/lib/evas/include/evas_inline.x
index fdf91dd..6afa69a 100644 (file)
--- a/src/lib/evas/include/evas_inline.x
+++ b/src/lib/evas/include/evas_inline.x
@@ -46,6 +46,7 @@ _evas_object_callback_has_by_type(Evas_Object_Protected_Data *obj, Evas_Callback
 static inline int
 evas_object_was_visible(Evas_Object *eo_obj, Evas_Object_Protected_Data *obj)
 {
+   if (EINA_UNLIKELY(!obj->prev)) return EINA_FALSE;
    if ((obj->prev->visible) && (!obj->no_render) &&
        ((obj->prev->cache.clip.visible) || obj->is_smart) &&
        ((obj->prev->cache.clip.a > 0 && obj->prev->render_op == EVAS_RENDER_BLEND)
@@ -156,6 +157,7 @@ evas_object_is_source_invisible(Evas_Object *eo_obj EINA_UNUSED, Evas_Object_Pro
 static inline int
 evas_object_is_visible(Evas_Object *eo_obj, Evas_Object_Protected_Data *obj)
 {
+   if (EINA_UNLIKELY(!obj->cur)) return EINA_FALSE;
    if ((obj->cur->visible) && (!obj->no_render) &&
        ((obj->cur->cache.clip.visible) || (obj->is_smart)) &&
        ((obj->cur->cache.clip.a > 0 && obj->cur->render_op == EVAS_RENDER_BLEND)