input/cursor: handle setting a NULL image surface1.3-rc2

This fixes a crash when attempting to listen to a signal on a NULL
cursor image surface. If the surface is NULL, the listener is just
reinitialized using wl_list_init.

1 files changed, 13 insertions, 7 deletions

diff --git a/sway/input/cursor.c b/sway/input/cursor.c
index 215dc767..9d14c585 100644
--- a/sway/input/cursor.c
+++ b/sway/input/cursor.c
@@ -798,6 +798,17 @@ static void handle_image_surface_destroy(struct wl_listener *listener,
         cursor_rebase(cursor);
 }
 
+static void set_image_surface(struct sway_cursor *cursor,
+                struct wlr_surface *surface) {
+        wl_list_remove(&cursor->image_surface_destroy.link);
+        cursor->image_surface = surface;
+        if (surface) {
+                wl_signal_add(&surface->events.destroy, &cursor->image_surface_destroy);
+        } else {
+                wl_list_init(&cursor->image_surface_destroy.link);
+        }
+}
+
 void cursor_set_image(struct sway_cursor *cursor, const char *image,
                 struct wl_client *client) {
         if (!(cursor->seat->wlr_seat->capabilities & WL_SEAT_CAPABILITY_POINTER)) {
@@ -805,10 +816,8 @@ void cursor_set_image(struct sway_cursor *cursor, const char *image,
         }
 
         const char *current_image = cursor->image;
+        set_image_surface(cursor, NULL);
         cursor->image = image;
-        wl_list_remove(&cursor->image_surface_destroy.link);
-        cursor->image_surface = NULL;
-        wl_list_init(&cursor->image_surface_destroy.link);
         cursor->hotspot_x = cursor->hotspot_y = 0;
         cursor->image_client = client;
 
@@ -831,11 +840,8 @@ void cursor_set_image_surface(struct sway_cursor *cursor,
                 return;
         }
 
+        set_image_surface(cursor, surface);
         cursor->image = NULL;
-        wl_list_remove(&cursor->image_surface_destroy.link);
-        cursor->image_surface = surface;
-        wl_signal_add(&cursor->image_surface->events.destroy,
-                        &cursor->image_surface_destroy);
         cursor->hotspot_x = hotspot_x;
         cursor->hotspot_y = hotspot_y;
         cursor->image_client = client;