[mutter/gnome-3-20] wayland: Don't handle input events after capability was removed

[Ray Strode <halfline src gnome org>]

commit f37b21e923311ed0d119cb302da2ae3fae4a322c
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Sep 2 11:50:29 2016 +0800

    wayland: Don't handle input events after capability was removed
    
    The seat capability updating is synchronous, but input events are
    asynchronous (first queued then emitted). This means we may end up in a
    situation where we from libinput first may receive a key event,
    immediately followed by a device-removed event. Clutter will first
    queue the key event, then remove the device, immediately triggering the
    seat capability removal.
    
    Later, when the clutter stage processes the queued events, the
    previously queued key event will be processed, eventually making it
    into MetaWaylandSeat. Before this patch, MetaWaylandSeat would still
    forward the key event to MetaWaylandKeyboard, even though it had
    'released' it. Doing this would cause referencing potentially freed
    memory, such as the xkb state that was unreferenced when the seat
    removed the capability.
    
    In order to avoid processing these lingering events, for now, just drop
    them on the floor if the capability has been removed.
    
    Eventually, the event queuing etc needs to be redesigned to work better
    when used in a Wayland compositor, but for now at least don't access
    freed memory.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=770727

 src/wayland/meta-wayland-seat.c |   20 +++++++++++++-------
 1 files changed, 13 insertions(+), 7 deletions(-)
---
diff --git a/src/wayland/meta-wayland-seat.c b/src/wayland/meta-wayland-seat.c
index 367c1f1..af42cfb 100644
--- a/src/wayland/meta-wayland-seat.c
+++ b/src/wayland/meta-wayland-seat.c
@@ -300,18 +300,21 @@ meta_wayland_seat_update (MetaWaylandSeat    *seat,
     case CLUTTER_BUTTON_PRESS:
     case CLUTTER_BUTTON_RELEASE:
     case CLUTTER_SCROLL:
-      meta_wayland_pointer_update (&seat->pointer, event);
+      if (seat->capabilities & WL_SEAT_CAPABILITY_POINTER)
+        meta_wayland_pointer_update (&seat->pointer, event);
       break;
 
     case CLUTTER_KEY_PRESS:
     case CLUTTER_KEY_RELEASE:
-      meta_wayland_keyboard_update (&seat->keyboard, (const ClutterKeyEvent *) event);
+      if (seat->capabilities & WL_SEAT_CAPABILITY_KEYBOARD)
+        meta_wayland_keyboard_update (&seat->keyboard, (const ClutterKeyEvent *) event);
       break;
 
     case CLUTTER_TOUCH_BEGIN:
     case CLUTTER_TOUCH_UPDATE:
     case CLUTTER_TOUCH_END:
-      meta_wayland_touch_update (&seat->touch, event);
+      if (seat->capabilities & WL_SEAT_CAPABILITY_TOUCH)
+        meta_wayland_touch_update (&seat->touch, event);
       break;
 
     default:
@@ -334,16 +337,19 @@ meta_wayland_seat_handle_event (MetaWaylandSeat *seat,
     case CLUTTER_SCROLL:
     case CLUTTER_TOUCHPAD_SWIPE:
     case CLUTTER_TOUCHPAD_PINCH:
-      return meta_wayland_pointer_handle_event (&seat->pointer, event);
+      if (seat->capabilities & WL_SEAT_CAPABILITY_POINTER)
+        return meta_wayland_pointer_handle_event (&seat->pointer, event);
 
     case CLUTTER_KEY_PRESS:
     case CLUTTER_KEY_RELEASE:
-      return meta_wayland_keyboard_handle_event (&seat->keyboard,
-                                                 (const ClutterKeyEvent *) event);
+      if (seat->capabilities & WL_SEAT_CAPABILITY_KEYBOARD)
+        return meta_wayland_keyboard_handle_event (&seat->keyboard,
+                                                   (const ClutterKeyEvent *) event);
     case CLUTTER_TOUCH_BEGIN:
     case CLUTTER_TOUCH_UPDATE:
     case CLUTTER_TOUCH_END:
-      return meta_wayland_touch_handle_event (&seat->touch, event);
+      if (seat->capabilities & WL_SEAT_CAPABILITY_TOUCH)
+        return meta_wayland_touch_handle_event (&seat->touch, event);
 
     default:
       break;