server: fail on global name overflow

display->id is initialized to 1, making 0 a convenient value to
indicate an invalid global name. Make sure to not return a zero
global name on overflow. Moreover, if we wrap around, we might
cycle back to a global name which is already in-use.

Signed-off-by: Simon Ser <contact@emersion.fr>

src/wayland-server.c

@@ -1285,6 +1285,11 @@ wl_global_create(struct wl_display *display,
 		return NULL;
 	}
 
+	if (display->id >= UINT32_MAX) {
+		wl_log("wl_global_create: ran out of global names\n");
+		return NULL;
+	}
+
 	global = zalloc(sizeof *global);
 	if (global == NULL)
 		return NULL;