new file mode 100644
--- /dev/null
+++ b/lib/mbscspn.c
@@ -0,0 +1,72 @@
+/* Searching a string for a character among a given set of characters.
+   Copyright (C) 1999, 2002, 2006-2007 Free Software Foundation, Inc.
+   Written by Bruno Haible <bruno@clisp.org>, 2007.
+
+   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.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <string.h>
+
+#if HAVE_MBRTOWC
+# include "mbuiter.h"
+#endif
+
+/* Find the first occurrence in the character string STRING of any character
+   in the character string ACCEPT.  Return the number of bytes from the
+   beginning of the string to this occurrence, or to the end of the string
+   if none exists.  */
+size_t
+mbscspn (const char *string, const char *accept)
+{
+  /* Optimize two cases.  */
+  if (accept[0] == '\0')
+    return strlen (string);
+  if (accept[1] == '\0')
+    {
+      const char *ptr = mbschr (string, accept[0]);
+      return (ptr != NULL ? ptr - string : strlen (string));
+    }
+  /* General case.  */
+#if HAVE_MBRTOWC
+  if (MB_CUR_MAX > 1)
+    {
+      mbui_iterator_t iter;
+
+      for (mbui_init (iter, string); mbui_avail (iter); mbui_advance (iter))
+	{
+	  if (mb_len (mbui_cur (iter)) == 1)
+	    {
+	      if (mbschr (accept, (unsigned char) * mbui_cur_ptr (iter)))
+		return mbui_cur_ptr (iter) - string;
+	    }
+	  else
+	    {
+	      mbui_iterator_t aiter;
+
+	      for (mbui_init (aiter, accept);
+		   mbui_avail (aiter);
+		   mbui_advance (aiter))
+		if (mb_equal (mbui_cur (aiter), mbui_cur (iter)))
+		  return mbui_cur_ptr (iter) - string;
+	    }
+	}
+      return strlen (string);
+    }
+  else
+#endif
+    return strcspn (string, accept);
+}