libc: fix strncmp

2 files changed, 7 insertions, 5 deletions

diff --git a/src/user/app/tests/libc/string.c b/src/user/app/tests/libc/string.c
index 2e00049..6afe350 100644
--- a/src/user/app/tests/libc/string.c
+++ b/src/user/app/tests/libc/string.c
@@ -55,6 +55,9 @@ static void test_strcmp(void) {
 	test(0 < strcmp("string", "str"));
 
 	test(0 != strcmp("stress", "string"));
+
+	test(0 != strncmp("abc", "ab", 3));
+	test(0 == strncmp("abc", "ab", 2));
 }
 
 static void test_strtol(void) {
diff --git a/src/user/lib/string/string.c b/src/user/lib/string/string.c
index f141a3d..126d175 100644
--- a/src/user/lib/string/string.c
+++ b/src/user/lib/string/string.c
@@ -109,12 +109,11 @@ char *strtok_r(char *restrict s, const char *restrict sep, char **restrict state
 }
 
 int strncmp(const char *s1, const char *s2, size_t n) {
-	while (n-- & *s1 && *s1 == *s2) {
-		s1++; s2++;
+	for (size_t i = 0; i < n; i++) {
+		if (s1[i] < s2[i]) return -1;
+		if (s1[i] > s2[i]) return  1;
 	}
-	if (*s1 == *s2) return  0;
-	if (*s1 <  *s2) return -1;
-	else            return  1;
+	return 0;
 }
 
 int strcoll(const char *s1, const char *s2) {