diff --git a/ap/libc/glibc/glibc-2.23/stdlib/mbtowc.c b/ap/libc/glibc/glibc-2.23/stdlib/mbtowc.c
new file mode 100644
index 0000000..0305788
--- /dev/null
+++ b/ap/libc/glibc/glibc-2.23/stdlib/mbtowc.c
@@ -0,0 +1,72 @@
+/* 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 <stdlib.h>
+#include <string.h>
+#include <wchar.h>
+#include <gconv.h>
+#include <wcsmbs/wcsmbsload.h>
+
+
+/* Convert the multibyte character at S, which is no longer
+   than N characters, to its `wchar_t' representation, placing
+   this n *PWC and returning its length.
+
+   Attention: this function should NEVER be intentionally used.
+   The interface is completely stupid.  The state is shared between
+   all conversion functions.  You should use instead the restartable
+   version `mbrtowc'.  */
+int
+mbtowc (wchar_t *pwc, const char *s, size_t n)
+{
+  int result;
+  static mbstate_t state;
+
+  /* If S is NULL the function has to return null or not null
+     depending on the encoding having a state depending encoding or
+     not.  */
+  if (s == NULL)
+    {
+      const struct gconv_fcts *fcts;
+
+      /* Get the conversion functions.  */
+      fcts = get_gconv_fcts (_NL_CURRENT_DATA (LC_CTYPE));
+
+      /* This is an extension in the Unix standard which does not directly
+	 violate ISO C.  */
+      memset (&state, '\0', sizeof state);
+
+      result = fcts->towc->__stateful;
+    }
+  else if (*s == '\0')
+    {
+      if (pwc != NULL)
+	*pwc = L'\0';
+      result = 0;
+    }
+  else
+    {
+      result = __mbrtowc (pwc, s, n, &state);
+
+      /* The `mbrtowc' functions tell us more than we need.  Fold the -1
+	 and -2 result into -1.  */
+      if (result < 0)
+	result = -1;
+    }
+
+  return result;
+}