[PATCH weston] xwayland: Fix crash when run with no input device

[Tom Hochstein]

Starting an xterm with no input device led to a crash
because weston_wm_pick_seat() was returning garbage and
weston_wm_selection_init() was trying to use the garbage.

Signed-off-by: Tom Hochstein <tom.hochstein at nxp.com>
---
 xwayland/selection.c      | 10 +++++++---
 xwayland/window-manager.c |  6 ++++--
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/xwayland/selection.c b/xwayland/selection.c
index 641ac49..60f9f20 100644
--- a/xwayland/selection.c
+++ b/xwayland/selection.c
@@ -655,8 +655,10 @@ weston_wm_set_selection(struct wl_listener *listener, void *data)
 	struct weston_seat *seat = data;
 	struct weston_wm *wm =
 		container_of(listener, struct weston_wm, selection_listener);
-	struct weston_data_source *source = seat->selection_data_source;
+	struct weston_data_source *source = NULL;
 
+	if (seat != NULL)
+		source = seat->selection_data_source;
 	if (source == NULL) {
 		if (wm->selection_owner == wm->selection_window)
 			xcb_set_selection_owner(wm->conn,
@@ -709,8 +711,10 @@ weston_wm_selection_init(struct weston_wm *wm)
 					  wm->atom.clipboard, mask);
 
 	seat = weston_wm_pick_seat(wm);
-	wm->selection_listener.notify = weston_wm_set_selection;
-	wl_signal_add(&seat->selection_signal, &wm->selection_listener);
+	if (seat != NULL) {
+		wm->selection_listener.notify = weston_wm_set_selection;
+		wl_signal_add(&seat->selection_signal, &wm->selection_listener);
+	}
 
 	weston_wm_set_selection(&wm->selection_listener, seat);
 }
diff --git a/xwayland/window-manager.c b/xwayland/window-manager.c
index 0e26d7c..15e2ca2 100644
--- a/xwayland/window-manager.c
+++ b/xwayland/window-manager.c
@@ -1306,8 +1306,10 @@ weston_wm_handle_reparent_notify(struct weston_wm *wm, xcb_generic_event_t *even
 struct weston_seat *
 weston_wm_pick_seat(struct weston_wm *wm)
 {
-	return container_of(wm->server->compositor->seat_list.next,
-			    struct weston_seat, link);
+	struct wl_list *seats = wm->server->compositor->seat_list.next;
+	if (wl_list_empty(seats))
+		return NULL;
+	return container_of(seats, struct weston_seat, link);
 }
 
 static struct weston_seat *
-- 
1.9.1