From 8998d7b95cddbb8a5103f753476927f9584a30b0 Mon Sep 17 00:00:00 2001
From: Joshua Judson Rosen
Date: Sun, 19 Mar 2017 16:34:33 -0400
Subject: robot-move: prevent crash on zero-length moves

---
 include/grobot.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/grobot.h b/include/grobot.h
index 52a7039..60796a9 100644
--- a/include/grobot.h
+++ b/include/grobot.h
@@ -66,7 +66,10 @@ struct _GRobotClass {
 /* some convenient macros */
 #define G_ROBOT_POSITION_X(robot)   ((robot)->x)
 #define G_ROBOT_POSITION_Y(robot)   ((robot)->y)
-#define sign(x)                     (x/abs(x))
+
+/* this is a little weird, but 0 case doesn't actually matter
+   given how the code in grobot.c uses this macro... */
+#define sign(x)                     (x ? x/abs(x) : 0)
 
 /* normal GObject stuff */
 GType g_robot_get_type(void) G_GNUC_CONST;
-- 
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