[clutter] x11: Avoid invalid ClutterInputDevice pointers in the device list

[Carlos Garnacho <carlosg src gnome org>]

commit 45935fbe29c544b2af72c9ab5a55c1a452e20b1c
Author: Carlos Garnacho <carlosg gnome org>
Date:   Sat Feb 22 20:35:23 2014 +0100

    x11: Avoid invalid ClutterInputDevice pointers in the device list
    
    Due to the way add_device() invariably adds to the master/slave device
    lists, while keeping ClutterInputDevices 1:1 with device IDs, it may
    leave invalid pointers in the list if add_device() is called multiple
    times for the same device ID. There are two situations where this may
    happen:
    
    1) If devices are disabled and later enabled: devices are added invariably
       to the master/slave lists on constructed(), but then on XIDeviceEnabled
       they'd get added yet again.
    2) Racy cases where the ClutterDeviceManager is created around the same time
       XIHierarchyEvents are sent. When getting the XIDeviceInfo on constructed(),
       these devices may already appear as enabled, even though XIDeviceEnabled
       is seen through XIHierarchyEvents processed in the event loop sortly after.
    
       This last case can be seen when starting gnome-shell on a different tty,
       and entering in the one it's been spawned on, clutter initialization
       happens around the same time devices are added back because of the tty
       switch, and multiple extra ClutterInputDevices are created.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=724971

 clutter/x11/clutter-device-manager-xi2.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)
---
diff --git a/clutter/x11/clutter-device-manager-xi2.c b/clutter/x11/clutter-device-manager-xi2.c
index 43c8f42..c77415c 100644
--- a/clutter/x11/clutter-device-manager-xi2.c
+++ b/clutter/x11/clutter-device-manager-xi2.c
@@ -402,7 +402,9 @@ translate_hierarchy_event (ClutterBackendX11       *backend_x11,
 
   for (i = 0; i < ev->num_info; i++)
     {
-      if (ev->info[i].flags & XIDeviceEnabled)
+      if (ev->info[i].flags & XIDeviceEnabled &&
+          !g_hash_table_lookup (manager_xi2->devices_by_id,
+                                GINT_TO_POINTER (ev->info[i].deviceid)))
         {
           XIDeviceInfo *info;
           int n_devices;
@@ -1383,6 +1385,9 @@ clutter_device_manager_xi2_constructed (GObject *gobject)
     {
       XIDeviceInfo *xi_device = &info[i];
 
+      if (!xi_device->enabled)
+        continue;
+
       add_device (manager_xi2, backend_x11, xi_device, TRUE);
 
       if (xi_device->use == XIMasterPointer ||