Wayland: ignore touch/tablet events on destroyed surfaces

When destroying a wl_surface (e.g. when a window or menu is closed), the
surface may continue to exist in the compositor slightly longer than on
the client side. In that case, the surface can still receive input
events, which need to be ignored gracefully.
In particular, this prevents segfaulting on wl_surface_get_user_data()
in that situation.

Reported in
https://gitlab.gnome.org/GNOME/gtk/-/issues/3296

The same issue for pointers/keyboards was reported in
https://bugzilla.gnome.org/show_bug.cgi?id=693338

and fixed with in
bfd7137ffb
3625f17857
a8fc099a72

gdk/wayland/gdkdevice-wayland.c

@@ -2460,6 +2460,9 @@ touch_handle_down (void              *data,
 
   _gdk_wayland_display_update_serial (display, serial);
 
+  if (!wl_surface)
+    return;
+
   touch = gdk_wayland_seat_add_touch (seat, id, wl_surface);
   touch->x = wl_fixed_to_double (x);
   touch->y = wl_fixed_to_double (y);
@@ -2495,6 +2498,9 @@ touch_handle_up (void            *data,
   _gdk_wayland_display_update_serial (display, serial);
 
   touch = gdk_wayland_seat_get_touch (seat, id);
+  if (!touch)
+    return;
+
   event = _create_touch_event (seat, touch, GDK_TOUCH_END, time);
 
   GDK_NOTE (EVENTS,
@@ -2521,6 +2527,9 @@ touch_handle_motion (void            *data,
   GdkEvent *event;
 
   touch = gdk_wayland_seat_get_touch (seat, id);
+  if (!touch)
+    return;
+
   touch->x = wl_fixed_to_double (x);
   touch->y = wl_fixed_to_double (y);
 
@@ -3634,19 +3643,21 @@ tablet_tool_handle_proximity_in (void                      *data,
                                  struct zwp_tablet_tool_v2 *wp_tablet_tool,
                                  uint32_t                   serial,
                                  struct zwp_tablet_v2      *wp_tablet,
-                                 struct wl_surface         *surface)
+                                 struct wl_surface         *wl_surface)
 {
   GdkWaylandTabletToolData *tool = data;
   GdkWaylandTabletData *tablet = zwp_tablet_v2_get_user_data (wp_tablet);
   GdkWaylandSeat *seat = GDK_WAYLAND_SEAT (tablet->seat);
   GdkWaylandDisplay *display_wayland = GDK_WAYLAND_DISPLAY (seat->display);
-  GdkWindow *window = wl_surface_get_user_data (surface);
+  GdkWindow *window;
   GdkEvent *event;
 
-  if (!surface)
+  if (!wl_surface)
-      return;
+    return;
+
+  window = wl_surface_get_user_data (wl_surface);
   if (!GDK_IS_WINDOW (window))
-      return;
+    return;
 
   tool->current_tablet = tablet;
   tablet->current_tool = tool;
@@ -3685,6 +3696,9 @@ tablet_tool_handle_proximity_out (void                      *data,
   GdkWaylandSeat *seat = GDK_WAYLAND_SEAT (tool->seat);
 #endif
 
+  if (!tablet)
+    return;
+
   GDK_NOTE (EVENTS,
             g_message ("proximity out, seat %p, tool %d", seat,
                        gdk_device_tool_get_tool_type (tool->tool)));
@@ -3741,7 +3755,7 @@ tablet_tool_handle_down (void                      *data,
   GdkWaylandSeat *seat = GDK_WAYLAND_SEAT (tool->seat);
   GdkWaylandDisplay *display_wayland = GDK_WAYLAND_DISPLAY (seat->display);
 
-  if (!tablet->pointer_info.focus)
+  if (!tablet || !tablet->pointer_info.focus)
     return;
 
   _gdk_wayland_display_update_serial (display_wayland, serial);
@@ -3758,7 +3772,7 @@ tablet_tool_handle_up (void                      *data,
   GdkWaylandTabletToolData *tool = data;
   GdkWaylandTabletData *tablet = tool->current_tablet;
 
-  if (!tablet->pointer_info.focus)
+  if (!tablet || !tablet->pointer_info.focus)
     return;
 
   tablet_create_button_event_frame (tablet, GDK_BUTTON_RELEASE, GDK_BUTTON_PRIMARY);
@@ -3777,6 +3791,9 @@ tablet_tool_handle_motion (void                      *data,
   GdkWaylandDisplay *display = GDK_WAYLAND_DISPLAY (seat->display);
   GdkEvent *event;
 
+  if (!tablet)
+    return;
+
   tablet->pointer_info.surface_x = wl_fixed_to_double (sx);
   tablet->pointer_info.surface_y = wl_fixed_to_double (sy);
 
@@ -3809,7 +3826,12 @@ tablet_tool_handle_pressure (void                      *data,
 {
   GdkWaylandTabletToolData *tool = data;
   GdkWaylandTabletData *tablet = tool->current_tablet;
-  gint axis_index = tablet->axis_indices[GDK_AXIS_PRESSURE];
+  gint axis_index;
+
+  if (!tablet)
+    return;
+
+  axis_index = tablet->axis_indices[GDK_AXIS_PRESSURE];
 
   _gdk_device_translate_axis (tablet->current_device, axis_index,
                               pressure, &tablet->axes[axis_index]);
@@ -3826,7 +3848,12 @@ tablet_tool_handle_distance (void                      *data,
 {
   GdkWaylandTabletToolData *tool = data;
   GdkWaylandTabletData *tablet = tool->current_tablet;
-  gint axis_index = tablet->axis_indices[GDK_AXIS_DISTANCE];
+  gint axis_index;
+
+  if (!tablet)
+    return;
+
+  axis_index = tablet->axis_indices[GDK_AXIS_DISTANCE];
 
   _gdk_device_translate_axis (tablet->current_device, axis_index,
                               distance, &tablet->axes[axis_index]);
@@ -3844,8 +3871,14 @@ tablet_tool_handle_tilt (void                      *data,
 {
   GdkWaylandTabletToolData *tool = data;
   GdkWaylandTabletData *tablet = tool->current_tablet;
-  gint xtilt_axis_index = tablet->axis_indices[GDK_AXIS_XTILT];
+  gint xtilt_axis_index;
-  gint ytilt_axis_index = tablet->axis_indices[GDK_AXIS_YTILT];
+  gint ytilt_axis_index;
+
+  if (!tablet)
+    return;
+
+  xtilt_axis_index = tablet->axis_indices[GDK_AXIS_XTILT];
+  ytilt_axis_index = tablet->axis_indices[GDK_AXIS_YTILT];
 
   _gdk_device_translate_axis (tablet->current_device, xtilt_axis_index,
                               wl_fixed_to_double (xtilt),
@@ -3872,7 +3905,7 @@ tablet_tool_handle_button (void                      *data,
   GdkEventType evtype;
   guint n_button;
 
-  if (!tablet->pointer_info.focus)
+  if (!tablet || !tablet->pointer_info.focus)
     return;
 
   tablet->pointer_info.press_serial = serial;
@@ -3903,7 +3936,12 @@ tablet_tool_handle_rotation (void                      *data,
 {
   GdkWaylandTabletToolData *tool = data;
   GdkWaylandTabletData *tablet = tool->current_tablet;
-  gint axis_index = tablet->axis_indices[GDK_AXIS_ROTATION];
+  gint axis_index;
+
+  if (!tablet)
+    return;
+
+  axis_index = tablet->axis_indices[GDK_AXIS_ROTATION];
 
   _gdk_device_translate_axis (tablet->current_device, axis_index,
                               wl_fixed_to_double (degrees),
@@ -3922,7 +3960,12 @@ tablet_tool_handle_slider (void                      *data,
 {
   GdkWaylandTabletToolData *tool = data;
   GdkWaylandTabletData *tablet = tool->current_tablet;
-  gint axis_index = tablet->axis_indices[GDK_AXIS_SLIDER];
+  gint axis_index;
+
+  if (!tablet)
+    return;
+
+  axis_index = tablet->axis_indices[GDK_AXIS_SLIDER];
 
   _gdk_device_translate_axis (tablet->current_device, axis_index,
                               position, &tablet->axes[axis_index]);
@@ -3940,9 +3983,12 @@ tablet_tool_handle_wheel (void                      *data,
 {
   GdkWaylandTabletToolData *tool = data;
   GdkWaylandTabletData *tablet = tool->current_tablet;
-  GdkWaylandSeat *seat = GDK_WAYLAND_SEAT (tablet->seat);
+  GdkWaylandSeat *seat;
   GdkEvent *event;
 
+  if (!tablet)
+    return;
+
   GDK_NOTE (EVENTS,
             g_message ("tablet tool %d wheel %d/%d",
                        gdk_device_tool_get_tool_type (tool->tool), degrees, clicks));
@@ -3950,6 +3996,8 @@ tablet_tool_handle_wheel (void                      *data,
   if (clicks == 0)
     return;
 
+  seat = GDK_WAYLAND_SEAT (tablet->seat);
+
   /* Send smooth event */
   event = create_scroll_event (seat, &tablet->pointer_info,
                                tablet->master, tablet->current_device, FALSE);
@@ -3975,6 +4023,9 @@ tablet_tool_handle_frame (void                      *data,
   GdkWaylandTabletData *tablet = tool->current_tablet;
   GdkEvent *frame_event;
 
+  if (!tablet)
+    return;
+
   GDK_NOTE (EVENTS,
             g_message ("tablet frame, time %d", time));