kern: lib: Add strncmp() function

Signed-off-by: Ian Moffett <ian@osmora.org>

2 files changed, 53 insertions, 0 deletions

diff --git a/sys/inc/lib/string.h b/sys/inc/lib/string.h
index 0ad7053..2c21c36 100644
--- a/sys/inc/lib/string.h
+++ b/sys/inc/lib/string.h
@@ -54,6 +54,9 @@ int snprintf(char *s, size_t size, const char *fmt, ...);
 /* POSIX memcmp() */
 int memcmp(const void *s1, const void *s2, size_t n);
 
+/* POSIX strncmp() */
+int strncmp(const char *s1, const char *s2, size_t n);
+
 /* Convert base int to string */
 char *itoa(int64_t value, char *buf, int base);
 
diff --git a/sys/lib/string/strncmp.c b/sys/lib/string/strncmp.c
new file mode 100644
index 0000000..aeac691
--- /dev/null
+++ b/sys/lib/string/strncmp.c
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <string.h>
+
+int
+strncmp(const char *s1, const char *s2, size_t n)
+{
+    if (n == 0) {
+        return 0;
+    }
+
+    do {
+        if (*s1 != *s2++) {
+            return (*(unsigned char *)s1 - *(unsigned char *)--s2);
+        }
+
+        if (*s1++ == 0) {
+            break;
+        }
+    } while (--n != 0);
+
+    return 0;
+}