diff --git a/ap/libc/glibc/glibc-2.23/string/test-strstr.c b/ap/libc/glibc/glibc-2.23/string/test-strstr.c
new file mode 100644
index 0000000..763edab
--- /dev/null
+++ b/ap/libc/glibc/glibc-2.23/string/test-strstr.c
@@ -0,0 +1,211 @@
+/* Test and measure strstr functions.
+   Copyright (C) 2010-2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Written by Ulrich Drepper <drepper@redhat.com>, 2010.
+
+   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/>.  */
+
+#define TEST_MAIN
+#define TEST_NAME "strstr"
+#include "test-string.h"
+
+
+#define STRSTR simple_strstr
+#include "strstr.c"
+
+
+static char *
+stupid_strstr (const char *s1, const char *s2)
+{
+  ssize_t s1len = strlen (s1);
+  ssize_t s2len = strlen (s2);
+
+  if (s2len > s1len)
+    return NULL;
+
+  for (ssize_t i = 0; i <= s1len - s2len; ++i)
+    {
+      size_t j;
+      for (j = 0; j < s2len; ++j)
+	if (s1[i + j] != s2[j])
+	  break;
+      if (j == s2len)
+	return (char *) s1 + i;
+    }
+
+  return NULL;
+}
+
+
+typedef char *(*proto_t) (const char *, const char *);
+
+IMPL (stupid_strstr, 0)
+IMPL (simple_strstr, 0)
+IMPL (strstr, 1)
+
+
+static int
+check_result (impl_t *impl, const char *s1, const char *s2,
+	      char *exp_result)
+{
+  char *result = CALL (impl, s1, s2);
+  if (result != exp_result)
+    {
+      error (0, 0, "Wrong result in function %s %s %s", impl->name,
+	     result, exp_result);
+      ret = 1;
+      return -1;
+    }
+
+  return 0;
+}
+
+static void
+do_one_test (impl_t *impl, const char *s1, const char *s2, char *exp_result)
+{
+  if (check_result (impl, s1, s2, exp_result) < 0)
+    return;
+}
+
+
+static void
+do_test (size_t align1, size_t align2, size_t len1, size_t len2,
+	 int fail)
+{
+  char *s1 = (char *) (buf1 + align1);
+  char *s2 = (char *) (buf2 + align2);
+
+  static const char d[] = "1234567890abcdef";
+#define dl (sizeof (d) - 1)
+  char *ss2 = s2;
+  for (size_t l = len2; l > 0; l = l > dl ? l - dl : 0)
+    {
+      size_t t = l > dl ? dl : l;
+      ss2 = mempcpy (ss2, d, t);
+    }
+  s2[len2] = '\0';
+
+  if (fail)
+    {
+      char *ss1 = s1;
+      for (size_t l = len1; l > 0; l = l > dl ? l - dl : 0)
+	{
+	  size_t t = l > dl ? dl : l;
+	  memcpy (ss1, d, t);
+	  ++ss1[len2 > 7 ? 7 : len2 - 1];
+	  ss1 += t;
+	}
+    }
+  else
+    {
+      memset (s1, '0', len1);
+      memcpy (s1 + len1 - len2, s2, len2);
+    }
+  s1[len1] = '\0';
+
+  FOR_EACH_IMPL (impl, 0)
+    do_one_test (impl, s1, s2, fail ? NULL : s1 + len1 - len2);
+
+}
+
+static void
+check1 (void)
+{
+  const char s1[] =
+    "F_BD_CE_BD_EF_BF_BD_EF_BF_BD_EF_BF_BD_EF_BF_BD_C3_88_20_EF_BF_BD_EF_BF_BD_EF_BF_BD_C3_A7_20_EF_BF_BD";
+  const char s2[] = "_EF_BF_BD_EF_BF_BD_EF_BF_BD_EF_BF_BD_EF_BF_BD";
+  char *exp_result;
+
+  exp_result = stupid_strstr (s1, s2);
+  FOR_EACH_IMPL (impl, 0)
+    check_result (impl, s1, s2, exp_result);
+}
+
+static void
+check2 (void)
+{
+  const char s1[] = ", enable_static, \0, enable_shared, ";
+  char *exp_result;
+  char *s2 = (void *) buf1 + page_size - 18;
+
+  strcpy (s2, s1);
+  exp_result = stupid_strstr (s1, s1 + 18);
+  FOR_EACH_IMPL (impl, 0)
+    {
+      check_result (impl, s1, s1 + 18, exp_result);
+      check_result (impl, s2, s1 + 18, exp_result);
+    }
+}
+
+static int
+test_main (void)
+{
+  test_init ();
+
+  check1 ();
+  check2 ();
+
+  printf ("%23s", "");
+  FOR_EACH_IMPL (impl, 0)
+    printf ("\t%s", impl->name);
+  putchar ('\n');
+
+  for (size_t klen = 2; klen < 32; ++klen)
+    for (size_t hlen = 2 * klen; hlen < 16 * klen; hlen += klen)
+      {
+	do_test (0, 0, hlen, klen, 0);
+	do_test (0, 0, hlen, klen, 1);
+	do_test (0, 3, hlen, klen, 0);
+	do_test (0, 3, hlen, klen, 1);
+	do_test (0, 9, hlen, klen, 0);
+	do_test (0, 9, hlen, klen, 1);
+	do_test (0, 15, hlen, klen, 0);
+	do_test (0, 15, hlen, klen, 1);
+
+	do_test (3, 0, hlen, klen, 0);
+	do_test (3, 0, hlen, klen, 1);
+	do_test (3, 3, hlen, klen, 0);
+	do_test (3, 3, hlen, klen, 1);
+	do_test (3, 9, hlen, klen, 0);
+	do_test (3, 9, hlen, klen, 1);
+	do_test (3, 15, hlen, klen, 0);
+	do_test (3, 15, hlen, klen, 1);
+
+	do_test (9, 0, hlen, klen, 0);
+	do_test (9, 0, hlen, klen, 1);
+	do_test (9, 3, hlen, klen, 0);
+	do_test (9, 3, hlen, klen, 1);
+	do_test (9, 9, hlen, klen, 0);
+	do_test (9, 9, hlen, klen, 1);
+	do_test (9, 15, hlen, klen, 0);
+	do_test (9, 15, hlen, klen, 1);
+
+	do_test (15, 0, hlen, klen, 0);
+	do_test (15, 0, hlen, klen, 1);
+	do_test (15, 3, hlen, klen, 0);
+	do_test (15, 3, hlen, klen, 1);
+	do_test (15, 9, hlen, klen, 0);
+	do_test (15, 9, hlen, klen, 1);
+	do_test (15, 15, hlen, klen, 0);
+	do_test (15, 15, hlen, klen, 1);
+      }
+
+  do_test (0, 0, page_size - 1, 16, 0);
+  do_test (0, 0, page_size - 1, 16, 1);
+
+  return ret;
+}
+
+#include "../test-skeleton.c"