wayland: check valid pending cairo surface

gdk_wayland_window_attach_image() is normally called from
gdk_window_end_paint() to notify the compositor of newly staged drawing.

If any of the drawing code inadvertently dispatches the wayland event
loop (for instance with a gdk_flush() call), then it's possible that by
the time gdk_window_end_paint() is called, the staged drawing is already
destroyed.

This commit bypasses the attach_image call in scenarios where the staged
drawing is prematurely dropped.

https://bugzilla.gnome.org/show_bug.cgi?id=773274

diff --git a/gdk/wayland/gdkwindow-wayland.c b/gdk/wayland/gdkwindow-wayland.c
index 41672fb656713c629141635460eb03c5847b86c2..c6c52a71b9415ddd228f2e5addc94c8b9f6bbfb0 100644 (file)
--- a/gdk/wayland/gdkwindow-wayland.c
+++ b/gdk/wayland/gdkwindow-wayland.c
@@ -896,7 +896,9 @@ gdk_window_impl_wayland_end_paint (GdkWindow *window)
   cairo_rectangle_int_t rect;
   int i, n;
 
-  if (!window->current_paint.use_gl &&
+  if (impl->staging_cairo_surface &&
+      _gdk_wayland_is_shm_surface (impl->staging_cairo_surface) &&
+      !window->current_paint.use_gl &&
       !cairo_region_is_empty (window->current_paint.region))
     {
       gdk_wayland_window_attach_image (window);