new file mode 100644
--- /dev/null
+++ b/lib/vsprintf.c
@@ -0,0 +1,72 @@
+/* Formatted output to strings.
+   Copyright (C) 2004, 2006-2007 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License along
+   with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+/* Specification.  */
+#include <stdio.h>
+
+#include <errno.h>
+#include <limits.h>
+#include <stdarg.h>
+#include <stdlib.h>
+
+#include "vasnprintf.h"
+
+/* Some systems, like OSF/1 4.0 and Woe32, don't have EOVERFLOW.  */
+#ifndef EOVERFLOW
+# define EOVERFLOW E2BIG
+#endif
+
+#ifndef SIZE_MAX
+# define SIZE_MAX ((size_t) -1)
+#endif
+
+/* Print formatted output to string STR.
+   Return string length of formatted string.  On error, return a negative
+   value. */
+int
+vsprintf (char *str, const char *format, va_list args)
+{
+  char *output;
+  size_t len;
+  size_t lenbuf = SIZE_MAX;
+
+  output = vasnprintf (str, &lenbuf, format, args);
+  len = lenbuf;
+
+  if (!output)
+    return -1;
+
+  if (output != str)
+    {
+      /* len is near SIZE_MAX.  */
+      free (output);
+      errno = EOVERFLOW;
+      return -1;
+    }
+
+  if (len > INT_MAX)
+    {
+      errno = EOVERFLOW;
+      return -1;
+    }
+
+  return len;
+}