[metacity] compositor: fix possible crash closing/destroying window

[Alberts Muktupāvels <muktupavels src gnome org>]

commit a9f28dbc26f5211ef08889109db3dc8c7ba76aca
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Tue Jul 7 13:49:30 2015 +0300

    compositor: fix possible crash closing/destroying window
    
    Partially restore call to destroy_win in compositor when calling
    meta_window_free. This is needed to ensure that we never call
    meta_window_get_frame_bounds while windows is destroying.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=751833

 src/compositor/compositor-private.h |    3 +++
 src/compositor/compositor-xrender.c |   34 +++++++++++++++++++++++++---------
 src/compositor/compositor.c         |    4 ++++
 3 files changed, 32 insertions(+), 9 deletions(-)
---
diff --git a/src/compositor/compositor-private.h b/src/compositor/compositor-private.h
index 11ed73b..a45fdc9 100644
--- a/src/compositor/compositor-private.h
+++ b/src/compositor/compositor-private.h
@@ -48,6 +48,9 @@ struct _MetaCompositor
                              MetaScreen     *screen,
                              MetaWindow     *window);
 
+  void (*free_window) (MetaCompositor *compositor,
+                       MetaWindow     *window);
+
   void (*maximize_window)   (MetaCompositor *compositor,
                              MetaWindow     *window);
   void (*unmaximize_window) (MetaCompositor *compositor,
diff --git a/src/compositor/compositor-xrender.c b/src/compositor/compositor-xrender.c
index 3bff70a..fbae9a7 100644
--- a/src/compositor/compositor-xrender.c
+++ b/src/compositor/compositor-xrender.c
@@ -2799,23 +2799,38 @@ xrender_end_move (MetaCompositor *compositor,
 #ifdef HAVE_COMPOSITE_EXTENSIONS
 #endif
 }
+#endif /* 0 */
 
 static void
 xrender_free_window (MetaCompositor *compositor,
                      MetaWindow     *window)
 {
 #ifdef HAVE_COMPOSITE_EXTENSIONS
-  /* FIXME: When an undecorated window is hidden this is called,
-     but the window does not get readded if it is subsequentally shown again
-     See http://bugzilla.gnome.org/show_bug.cgi?id=504876
-
-     I don't *think* theres any need for this call anyway, leaving it out
-     does not seem to cause any side effects so far, but I should check with
-     someone who understands more. */
-  /* destroy_win (compositor->display, window->xwindow, FALSE); */
+  MetaCompositorXRender *xrc;
+  MetaFrame *frame;
+  Window xwindow;
+
+  xrc = (MetaCompositorXRender *) compositor;
+  frame = meta_window_get_frame (window);
+  xwindow = None;
+
+  if (frame)
+    {
+      xwindow = meta_frame_get_xwindow (frame);
+    }
+  else
+    {
+      /* FIXME: When an undecorated window is hidden this is called, but the
+       * window does not get readded if it is subsequentally shown again. See:
+       * http://bugzilla.gnome.org/show_bug.cgi?id=504876
+       */
+      /* xwindow = meta_window_get_xwindow (window); */
+    }
+
+  if (xwindow != None)
+    destroy_win (xrc->display, xwindow, FALSE);
 #endif
 }
-#endif /* 0 */
 
 static void
 xrender_process_event (MetaCompositor *compositor,
@@ -3095,6 +3110,7 @@ static MetaCompositor comp_info = {
   xrender_process_event,
   xrender_get_window_pixmap,
   xrender_set_active_window,
+  xrender_free_window,
   xrender_maximize_window,
   xrender_unmaximize_window,
 };
diff --git a/src/compositor/compositor.c b/src/compositor/compositor.c
index 0dcf2b2..1fea362 100644
--- a/src/compositor/compositor.c
+++ b/src/compositor/compositor.c
@@ -154,6 +154,10 @@ void meta_compositor_end_move (MetaCompositor *compositor,
 void meta_compositor_free_window (MetaCompositor *compositor,
                                   MetaWindow     *window)
 {
+#ifdef HAVE_COMPOSITE_EXTENSIONS
+  if (compositor && compositor->free_window)
+    compositor->free_window (compositor, window);
+#endif
 }
 
 void