From aa9ea95e1fffde31be72ffaf204a3aaf2893858e Mon Sep 17 00:00:00 2001
From: Alynx Zhou <alynx.zhou@gmail.com>
Date: Fri, 8 Nov 2019 15:10:43 +0800
Subject: [PATCH] Skip assign when sub_x or sub_y is NULL in
 wlr_surface_surface_at

---
 types/wlr_surface.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/types/wlr_surface.c b/types/wlr_surface.c
index ca10e08b..9503b8d4 100644
--- a/types/wlr_surface.c
+++ b/types/wlr_surface.c
@@ -1016,8 +1016,12 @@ struct wlr_surface *wlr_surface_surface_at(struct wlr_surface *surface,
 	}
 
 	if (wlr_surface_point_accepts_input(surface, sx, sy)) {
-		*sub_x = sx;
-		*sub_y = sy;
+		if (sub_x) {
+			*sub_x = sx;
+		}
+		if (sub_y) {
+			*sub_y = sy;
+		}
 		return surface;
 	}