[gtk+] wayland: Prepare against NULL selection owners on data_source requests

[Carlos Garnacho <carlosg src gnome org>]

commit 50178ce0147388ceffd7cafedfd85befcdfc4137
Author: Carlos Garnacho <carlosg gnome org>
Date:   Mon Jun 29 16:32:01 2015 +0200

    wayland: Prepare against NULL selection owners on data_source requests
    
    Currently, due to the lack of progress information in the Wayland DnD
    protocol, we assume a DnD operation is finished after the first
    data_source.send is finished (It's either that or leaving stuck grabs).
    
    This however breaks previous assumptions that dest widgets can request
    the data multiple times, even in response to GtkWidget::drag-motion.
    This leaves us with a NULL owner for the DnD atom when we aren't
    finished receiving wl_data_source events yet, causing a crash.
    
    This commit fixes the crash, the behavior left is still far from
    desirable though...

 gdk/wayland/gdkselection-wayland.c |    8 ++++++--
 1 files changed, 6 insertions(+), 2 deletions(-)
---
diff --git a/gdk/wayland/gdkselection-wayland.c b/gdk/wayland/gdkselection-wayland.c
index 455b0e6..640fa4e 100644
--- a/gdk/wayland/gdkselection-wayland.c
+++ b/gdk/wayland/gdkselection-wayland.c
@@ -705,7 +705,7 @@ data_source_target (void                  *data,
 {
   GdkWaylandSelection *wayland_selection = data;
   GdkDragContext *context = NULL;
-  GdkWindow *window;
+  GdkWindow *window = NULL;
 
   g_debug (G_STRLOC ": %s source = %p, mime_type = %s",
            G_STRFUNC, source, mime_type);
@@ -732,7 +732,8 @@ data_source_target (void                  *data,
     }
   else if (source == wayland_selection->clipboard_source)
     window = wayland_selection->clipboard_owner;
-  else
+
+  if (!window)
     return;
 
   gdk_wayland_selection_request_target (wayland_selection, window,
@@ -771,6 +772,9 @@ data_source_send (void                  *data,
       return;
     }
 
+  if (!window)
+    return;
+
   if (!gdk_wayland_selection_request_target (wayland_selection, window,
                                              gdk_atom_intern (mime_type, FALSE),
                                              fd))