From f7590c1c5aa46d846b2589dbae90a9a7ebc5a86d Mon Sep 17 00:00:00 2001
From: Mark Andrews <marka@isc.org>
Date: Fri, 19 Aug 2022 11:13:59 +1000
Subject: [PATCH] Silence negative array index warning with toupper

Cast to (unsigned char).

(cherry picked from commit d3f790340e8590ad5da1472c99d25acbc9818496)
---
 lib/isccfg/duration.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/isccfg/duration.c b/lib/isccfg/duration.c
index 27dddca1cc..305047e1af 100644
--- a/lib/isccfg/duration.c
+++ b/lib/isccfg/duration.c
@@ -63,7 +63,7 @@ isccfg_duration_fromtext(isc_textregion_t *source,
 	duration->unlimited = false;
 
 	/* Every duration starts with 'P' */
-	if (toupper(str[0]) != 'P') {
+	if (toupper((unsigned char)str[0]) != 'P') {
 		return (ISC_R_BADNUMBER);
 	}
 	P = str;