From 78b9c0b9cd6318fce43bf984b9892c2593c7c2b3 Mon Sep 17 00:00:00 2001
From: Alex Kotov <kotovalexarian@gmail.com>
Date: Fri, 10 Jun 2022 09:06:29 +0300
Subject: [PATCH] Main: libc/include/string.h: Add func "strncat"

---
 libc/include/string.h |  1 +
 libc/src/string.c     | 15 +++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/libc/include/string.h b/libc/include/string.h
index 83b9c90..840c68b 100644
--- a/libc/include/string.h
+++ b/libc/include/string.h
@@ -16,6 +16,7 @@ char *strcat(char *dest, const char *src);
 int strcmp(const char *s1, const char *s2);
 char *strcpy(char *dest, const char *src);
 size_t strlen(const char *s);
+char *strncat(char *dest, const char *src, size_t n);
 int strncmp(const char *s1, const char *s2, size_t n);
 char *strncpy(char *dest, const char *src, size_t n);
 size_t strnlen(const char *s, size_t maxlen);
diff --git a/libc/src/string.c b/libc/src/string.c
index a92432d..64c4220 100644
--- a/libc/src/string.c
+++ b/libc/src/string.c
@@ -78,6 +78,21 @@ size_t strlen(const char *s)
     return ss - s;
 }
 
+char *strncat(char *dest, const char *src, size_t n)
+{
+    char *const dest_start = dest;
+    if (n) {
+        while (*dest++);
+        while ((*dest++ = *src++)) {
+            if (--n == 0) {
+                *dest = '\0';
+                break;
+            }
+        }
+    }
+    return dest_start;
+}
+
 int strncmp(const char *s1, const char *s2, size_t n)
 {
     for (; *s1 && n; ++s1, ++s2, --n) if (*s1 != *s2) return *s1 < *s2 ? -1 : 1;