From 89fa9354160307aecb2d60f4a9addaeecdd2db68 Mon Sep 17 00:00:00 2001
From: "Darryl L. Miles" <darryl.miles@darrylmiles.org>
Date: Wed, 16 Oct 2024 10:20:51 +0100
Subject: [PATCH] grTk1.c: GrTkIconUpdate() potential -1 out-of-bound access

SonarCloud
Access of 'char' element in the region at index -1
This was not picked up, even though similar code was.
---
 graphics/grTk1.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/graphics/grTk1.c b/graphics/grTk1.c
index ea31b786..ada54efa 100644
--- a/graphics/grTk1.c
+++ b/graphics/grTk1.c
@@ -1754,7 +1754,9 @@ GrTkIconUpdate(w, text)		/* See Blt code */
     class.res_class = "magic";
 
     XSetClassHint( grXdpy, wind, &class);
-    if ((brack = strchr(text,'[')))
+    if (text == NULL)
+        return;
+    if ((brack = strchr(text,'[')) && brack != text)
     {
      	brack--;
 	*brack = 0;