From ceaae49b2d7b935f849f065c4ec2e9d3537c9e1b Mon Sep 17 00:00:00 2001
From: Benno Schulenberg <bensberg@telfort.nl>
Date: Sun, 23 May 2021 11:46:37 +0200
Subject: [PATCH] tweaks: avoid the subtraction of two size_t variables
 becoming negative

This fixes https://savannah.gnu.org/bugs/?60658.

Found by compiling with -fsanitize=undefined.
---
 src/chars.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/chars.c b/src/chars.c
index 5122401d..e733f6f4 100644
--- a/src/chars.c
+++ b/src/chars.c
@@ -540,7 +540,7 @@ char *mbrevstrcasestr(const char *haystack, const char *needle,
 		size_t tail_len = mbstrlen(pointer);
 
 		if (tail_len < needle_len)
-			pointer += tail_len - needle_len;
+			pointer -= (needle_len - tail_len);
 
 		if (pointer < haystack)
 			return NULL;