[PATCH xserver] xwayland: Activate and enable touch devices

[Olivier Fourdan]

On some random condition, a touch event may trigger a crash in Xwayland
in GetTouchEvents().

The (simplified) backtrace goes as follow:

 (gdb) bt
 #0  GetTouchEvents() at getevents.c:1892
 #1  QueueTouchEvents() at getevents.c:1866
 #2  xwl_touch_send_event() at xwayland-input.c:652
 #5  wl_closure_invoke() from libwayland-client.so.0
 #6  dispatch_event() from libwayland-client.so.0
 #7  wl_display_dispatch_queue_pending() from libwayland-client.so.0
 #8  xwl_read_events() at xwayland.c:483
 #9  ospoll_wait() at ospoll.c:412
 #10 WaitForSomething() at WaitFor.c:222
 #11 Dispatch() at dispatch.c:412
 #12 dix_main() at main.c:287
 #13 __libc_start_main() at libc-start.c:289
 #14 _start ()

The crash occurs when trying to access the sprite associated with the
touch device, which appears to be NULL. Reason being the device itself
is more a keyboard device than a touch device.

Moreover, it appears the device is neither enabled nor activated
(inited=0, enabled=0) which doesn't seem right, but matches the code in
init_touch() from xwayland-input.c which would enable the device if it
was previously existing and otherwise would create the device but not
activate it.

Make sure we do activate and enable touch devices just like we do for
other input devices such as keyboard and pointer.

Signed-off-by: Olivier Fourdan <ofourdan at redhat.com>
---
 hw/xwayland/xwayland-input.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/hw/xwayland/xwayland-input.c b/hw/xwayland/xwayland-input.c
index 4d447a5..9a7123a 100644
--- a/hw/xwayland/xwayland-input.c
+++ b/hw/xwayland/xwayland-input.c
@@ -1056,12 +1056,13 @@ init_touch(struct xwl_seat *xwl_seat)
     wl_touch_add_listener(xwl_seat->wl_touch,
                           &touch_listener, xwl_seat);
 
-    if (xwl_seat->touch)
-        EnableDevice(xwl_seat->touch, TRUE);
-    else {
+    if (xwl_seat->touch == NULL) {
         xwl_seat->touch =
             add_device(xwl_seat, "xwayland-touch", xwl_touch_proc);
+        ActivateDevice(xwl_seat->touch, TRUE);
     }
+    EnableDevice(xwl_seat->touch, TRUE);
+
 }
 
 static void
-- 
2.9.3