diff --git a/ap/libc/glibc/glibc-2.23/string/strncmp.c b/ap/libc/glibc/glibc-2.23/string/strncmp.c
new file mode 100644
index 0000000..b77a334
--- /dev/null
+++ b/ap/libc/glibc/glibc-2.23/string/strncmp.c
@@ -0,0 +1,74 @@
+/* Copyright (C) 1991-2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <string.h>
+#include <memcopy.h>
+
+#undef strncmp
+
+#ifndef STRNCMP
+#define STRNCMP strncmp
+#endif
+
+/* Compare no more than N characters of S1 and S2,
+   returning less than, equal to or greater than zero
+   if S1 is lexicographically less than, equal to or
+   greater than S2.  */
+int
+STRNCMP (const char *s1, const char *s2, size_t n)
+{
+  unsigned char c1 = '\0';
+  unsigned char c2 = '\0';
+
+  if (n >= 4)
+    {
+      size_t n4 = n >> 2;
+      do
+	{
+	  c1 = (unsigned char) *s1++;
+	  c2 = (unsigned char) *s2++;
+	  if (c1 == '\0' || c1 != c2)
+	    return c1 - c2;
+	  c1 = (unsigned char) *s1++;
+	  c2 = (unsigned char) *s2++;
+	  if (c1 == '\0' || c1 != c2)
+	    return c1 - c2;
+	  c1 = (unsigned char) *s1++;
+	  c2 = (unsigned char) *s2++;
+	  if (c1 == '\0' || c1 != c2)
+	    return c1 - c2;
+	  c1 = (unsigned char) *s1++;
+	  c2 = (unsigned char) *s2++;
+	  if (c1 == '\0' || c1 != c2)
+	    return c1 - c2;
+	} while (--n4 > 0);
+      n &= 3;
+    }
+
+  while (n > 0)
+    {
+      c1 = (unsigned char) *s1++;
+      c2 = (unsigned char) *s2++;
+      if (c1 == '\0' || c1 != c2)
+	return c1 - c2;
+      n--;
+    }
+
+  return c1 - c2;
+}
+
+libc_hidden_builtin_def (STRNCMP)