diff --git a/ap/libc/glibc/glibc-2.23/string/envz.c b/ap/libc/glibc/glibc-2.23/string/envz.c
new file mode 100644
index 0000000..68343f3
--- /dev/null
+++ b/ap/libc/glibc/glibc-2.23/string/envz.c
@@ -0,0 +1,172 @@
+/* Routines for dealing with '\0' separated environment vectors
+   Copyright (C) 1995-2016 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Written by Miles Bader <miles@gnu.org>
+
+   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 <malloc.h>
+#include <string.h>
+
+#include <envz.h>
+
+/* The character separating names from values in an envz.  */
+#define SEP '='
+
+/* Returns a pointer to the entry in ENVZ for NAME, or 0 if there is none.
+   If NAME contains the separator character, only the portion before it is
+   used in the comparison.  */
+char *
+envz_entry (const char *envz, size_t envz_len, const char *name)
+{
+  while (envz_len)
+    {
+      const char *p = name;
+      const char *entry = envz;	/* Start of this entry. */
+
+      /* See how far NAME and ENTRY match.  */
+      while (envz_len && *p == *envz && *p && *p != SEP)
+	p++, envz++, envz_len--;
+
+      if ((*envz == '\0' || *envz == SEP) && (*p == '\0' || *p == SEP))
+	/* Bingo! */
+	return (char *) entry;
+
+      /* No match, skip to the next entry.  */
+      while (envz_len && *envz)
+	envz++, envz_len--;
+      if (envz_len)
+	envz++, envz_len--;	/* skip '\0' */
+    }
+
+  return 0;
+}
+libc_hidden_def (envz_entry)
+
+/* Returns a pointer to the value portion of the entry in ENVZ for NAME, or 0
+   if there is none.  */
+char *
+envz_get (const char *envz, size_t envz_len, const char *name)
+{
+  char *entry = envz_entry (envz, envz_len, name);
+  if (entry)
+    {
+      while (*entry && *entry != SEP)
+	entry++;
+      if (*entry)
+	entry++;
+      else
+	entry = 0;		/* A null entry.  */
+    }
+  return entry;
+}
+
+/* Remove the entry for NAME from ENVZ & ENVZ_LEN, if any.  */
+void
+envz_remove (char **envz, size_t *envz_len, const char *name)
+{
+  char *entry = envz_entry (*envz, *envz_len, name);
+  if (entry)
+    argz_delete (envz, envz_len, entry);
+}
+libc_hidden_def (envz_remove)
+
+/* Adds an entry for NAME with value VALUE to ENVZ & ENVZ_LEN.  If an entry
+   with the same name already exists in ENVZ, it is removed.  If VALUE is
+   NULL, then the new entry will a special null one, for which envz_get will
+   return NULL, although envz_entry will still return an entry; this is handy
+   because when merging with another envz, the null entry can override an
+   entry in the other one.  Null entries can be removed with envz_strip ().  */
+error_t
+envz_add (char **envz, size_t *envz_len, const char *name, const char *value)
+{
+  envz_remove (envz, envz_len, name);
+
+  if (value)
+    /* Add the new value, if there is one.  */
+    {
+      size_t name_len = strlen (name);
+      size_t value_len = strlen (value);
+      size_t old_envz_len = *envz_len;
+      size_t new_envz_len = old_envz_len + name_len + 1 + value_len + 1;
+      char *new_envz = realloc (*envz, new_envz_len);
+
+      if (new_envz)
+	{
+	  memcpy (new_envz + old_envz_len, name, name_len);
+	  new_envz[old_envz_len + name_len] = SEP;
+	  memcpy (new_envz + old_envz_len + name_len + 1, value, value_len);
+	  new_envz[new_envz_len - 1] = 0;
+
+	  *envz = new_envz;
+	  *envz_len = new_envz_len;
+
+	  return 0;
+	}
+      else
+	return ENOMEM;
+    }
+  else
+    /* Add a null entry.  */
+    return __argz_add (envz, envz_len, name);
+}
+
+/* Adds each entry in ENVZ2 to ENVZ & ENVZ_LEN, as if with envz_add().  If
+   OVERRIDE is true, then values in ENVZ2 will supersede those with the same
+   name in ENV, otherwise not.  */
+error_t
+envz_merge (char **envz, size_t *envz_len, const char *envz2,
+	    size_t envz2_len, int override)
+{
+  error_t err = 0;
+
+  while (envz2_len && ! err)
+    {
+      char *old = envz_entry (*envz, *envz_len, envz2);
+      size_t new_len = strlen (envz2) + 1;
+
+      if (! old)
+	err = __argz_append (envz, envz_len, envz2, new_len);
+      else if (override)
+	{
+	  argz_delete (envz, envz_len, old);
+	  err = __argz_append (envz, envz_len, envz2, new_len);
+	}
+
+      envz2 += new_len;
+      envz2_len -= new_len;
+    }
+
+  return err;
+}
+
+/* Remove null entries.  */
+void
+envz_strip (char **envz, size_t *envz_len)
+{
+  char *entry = *envz;
+  size_t left = *envz_len;
+  while (left)
+    {
+      size_t entry_len = strlen (entry) + 1;
+      left -= entry_len;
+      if (! strchr (entry, SEP))
+	/* Null entry. */
+	memmove (entry, entry + entry_len, left);
+      else
+	entry += entry_len;
+    }
+  *envz_len = entry - *envz;
+}