libc: string: Add POSIX strnlen()

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

2 files changed, 23 insertions, 0 deletions

diff --git a/src/lib/libc/include/string.h b/src/lib/libc/include/string.h
index 83bb551..58a7caa 100644
--- a/src/lib/libc/include/string.h
+++ b/src/lib/libc/include/string.h
@@ -39,4 +39,13 @@
  */
 size_t strlen(const char *s);
 
+/*
+ * Get the length of a string with a maximum
+ * length
+ *
+ * @s: String to check length of
+ * @maxlen: Max length of string to check
+ */
+size_t strnlen(const char *s, size_t maxlen);
+
 #endif  /* _STRING_H */
diff --git a/src/lib/libc/src/string/strlen.c b/src/lib/libc/src/string/strlen.c
index de02ad9..59184e8 100644
--- a/src/lib/libc/src/string/strlen.c
+++ b/src/lib/libc/src/string/strlen.c
@@ -38,3 +38,17 @@ strlen(const char *s)
     while (s[len++] != '\0');
     return len - 1;
 }
+
+size_t
+strnlen(const char *s, size_t maxlen)
+{
+    size_t len = 0;
+
+    while (s[len++] != '\0') {
+        if (len >= maxlen) {
+            return len - 1;
+        }
+    }
+
+    return len - 1;
+}