diff --git a/ap/libc/glibc/glibc-2.23/string/strsignal.c b/ap/libc/glibc/glibc-2.23/string/strsignal.c
new file mode 100644
index 0000000..706d6d3
--- /dev/null
+++ b/ap/libc/glibc/glibc-2.23/string/strsignal.c
@@ -0,0 +1,125 @@
+/* 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 <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <libintl.h>
+#include <libc-lock.h>
+
+static __libc_key_t key;
+
+/* If nonzero the key allocation failed and we should better use a
+   static buffer than fail.  */
+#define BUFFERSIZ	100
+static char local_buf[BUFFERSIZ];
+static char *static_buf;
+
+/* Destructor for the thread-specific data.  */
+static void init (void);
+static void free_key_mem (void *mem);
+static char *getbuffer (void);
+
+
+/* Return a string describing the meaning of the signal number SIGNUM.  */
+char *
+strsignal (int signum)
+{
+  __libc_once_define (static, once);
+  const char *desc;
+
+  /* If we have not yet initialized the buffer do it now.  */
+  __libc_once (once, init);
+
+  if (
+#ifdef SIGRTMIN
+      (signum >= SIGRTMIN && signum <= SIGRTMAX) ||
+#endif
+      signum < 0 || signum >= NSIG
+      || (desc = _sys_siglist[signum]) == NULL)
+    {
+      char *buffer = getbuffer ();
+      int len;
+#ifdef SIGRTMIN
+      if (signum >= SIGRTMIN && signum <= SIGRTMAX)
+	len = __snprintf (buffer, BUFFERSIZ - 1, _("Real-time signal %d"),
+			  signum - SIGRTMIN);
+      else
+#endif
+	len = __snprintf (buffer, BUFFERSIZ - 1, _("Unknown signal %d"),
+			  signum);
+      if (len >= BUFFERSIZ)
+	buffer = NULL;
+      else
+	buffer[len] = '\0';
+
+      return buffer;
+    }
+
+  return (char *) _(desc);
+}
+
+
+/* Initialize buffer.  */
+static void
+init (void)
+{
+  if (__libc_key_create (&key, free_key_mem))
+    /* Creating the key failed.  This means something really went
+       wrong.  In any case use a static buffer which is better than
+       nothing.  */
+    static_buf = local_buf;
+}
+
+
+/* Free the thread specific data, this is done if a thread terminates.  */
+static void
+free_key_mem (void *mem)
+{
+  free (mem);
+  __libc_setspecific (key, NULL);
+}
+
+
+/* Return the buffer to be used.  */
+static char *
+getbuffer (void)
+{
+  char *result;
+
+  if (static_buf != NULL)
+    result = static_buf;
+  else
+    {
+      /* We don't use the static buffer and so we have a key.  Use it
+	 to get the thread-specific buffer.  */
+      result = __libc_getspecific (key);
+      if (result == NULL)
+	{
+	  /* No buffer allocated so far.  */
+	  result = malloc (BUFFERSIZ);
+	  if (result == NULL)
+	    /* No more memory available.  We use the static buffer.  */
+	    result = local_buf;
+	  else
+	    __libc_setspecific (key, result);
+	}
+    }
+
+  return result;
+}