From 283b6bd7619d7c3f3c98dbeccaeb27e70b9ea38f Mon Sep 17 00:00:00 2001
From: Masatake Daimon
Date: Fri, 7 Nov 2025 01:42:00 +0900
Subject: utils: Correct ctype(3) usage

According to POSIX.1 the argument of ctype(3) functions, including
toupper(3), has to either be EOF or a value representable as an unsigned
char. If the argument has any other value, the behavior is undefined. This
means values of signed char must first be cast to unsigned char, otherwise
they will be outside the range of allowed values.

glibc attempts to avoid the undefined behavior by defining the functions to
work for all integer inputs representable by either an unsigned char or a
signed char. NetBSD libc does not, and causes a segfault if the value is
invalid.
---
 src/utils.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'src/utils.c')

diff --git a/src/utils.c b/src/utils.c
index 2c5c15d..33b76d6 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -220,7 +220,7 @@ char *string_toupper(char* str)
 	char *res = strdup(str);
 	size_t i;
 	for (i = 0; i < strlen(res); i++) {
-		res[i] = toupper(res[i]);
+		res[i] = toupper((unsigned char)res[i]);
 	}
 	return res;
 }
-- 
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