[mutter] wayland: Handle wl_data_device being destroyed while focused

[Jonas Ådahl <jadahl src gnome org>]

commit 08ac192b9d99d9c8c0fff484d803f10740e7e415
Author: Jonas Ådahl <jadahl gmail com>
Date:   Mon Apr 25 18:42:57 2016 +0800

    wayland: Handle wl_data_device being destroyed while focused
    
    A wl_data_device object may be created while it is being focused,
    either because the client destroyed it or because the client was
    destroyed. Handle this by early out in focus handler vfuncs the case
    where it was destroyed, so that we don't corrupt memory and/or cause
    segmentation fault.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=765062

 src/wayland/meta-wayland-data-device.c |   11 +++++++++--
 1 files changed, 9 insertions(+), 2 deletions(-)
---
diff --git a/src/wayland/meta-wayland-data-device.c b/src/wayland/meta-wayland-data-device.c
index c7b324f..96d03c9 100644
--- a/src/wayland/meta-wayland-data-device.c
+++ b/src/wayland/meta-wayland-data-device.c
@@ -1424,9 +1424,10 @@ meta_wayland_drag_dest_focus_out (MetaWaylandDataDevice *data_device,
 {
   MetaWaylandDragGrab *grab = data_device->current_grab;
 
-  if (grab->drag_focus_data_device)
-    wl_data_device_send_leave (grab->drag_focus_data_device);
+  if (!grab->drag_focus_data_device)
+    return;
 
+  wl_data_device_send_leave (grab->drag_focus_data_device);
   wl_list_remove (&grab->drag_focus_listener.link);
   grab->drag_focus_data_device = NULL;
 }
@@ -1439,6 +1440,9 @@ meta_wayland_drag_dest_motion (MetaWaylandDataDevice *data_device,
   MetaWaylandDragGrab *grab = data_device->current_grab;
   wl_fixed_t sx, sy;
 
+  if (!grab->drag_focus_data_device)
+    return;
+
   meta_wayland_pointer_get_relative_coordinates (grab->generic.pointer,
                                                  grab->drag_focus,
                                                  &sx, &sy);
@@ -1453,6 +1457,9 @@ meta_wayland_drag_dest_drop (MetaWaylandDataDevice *data_device,
 {
   MetaWaylandDragGrab *grab = data_device->current_grab;
 
+  if (!grab->drag_focus_data_device)
+    return;
+
   wl_data_device_send_drop (grab->drag_focus_data_device);
 }