/* Convert wide string to string.
   Copyright (C) 2008 Free Software Foundation, Inc.
   Written by Bruno Haible <bruno@clisp.org>, 2008.

   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 3 of the License, 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, see <http://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */
#include <wchar.h>

#include <errno.h>
#include <stdlib.h>
#include <string.h>


extern mbstate_t _gl_wcsrtombs_state;

size_t
wcsnrtombs (char *dest, const wchar_t **srcp, size_t srclen, size_t len, mbstate_t *ps)
{
  if (ps == NULL)
    ps = &_gl_wcsrtombs_state;
  {
    const wchar_t *src = *srcp;
    size_t cur_max = MB_CUR_MAX;
    char buf[64];

    if (!(cur_max <= sizeof (buf)))
      abort ();

    if (dest != NULL)
      {
	char *destptr = dest;

	for (; srclen > 0 && len > 0; src++, srclen--)
	  {
	    wchar_t wc = *src;
	    size_t ret = wcrtomb (len >= cur_max ? destptr : buf, wc, ps);

	    if (ret == (size_t)(-1))
	      goto bad_input;
	    if (!(ret <= cur_max))
	      abort ();
	    if (len < ret)
	      break;
	    if (len < cur_max)
	      memcpy (destptr, buf, ret);
	    if (wc == 0)
	      {
		src = NULL;
		/* Here mbsinit (ps).  */
		break;
	      }
	    destptr += ret;
	    len -= ret;
	  }
	*srcp = src;
	return destptr - dest;
      }
    else
      {
	/* Ignore dest and len, don't store *srcp at the end, and
	   don't clobber *ps.  */
	mbstate_t state = *ps;
	size_t totalcount = 0;

	for (; srclen > 0; src++, srclen--)
	  {
	    wchar_t wc = *src;
	    size_t ret = wcrtomb (buf, wc, &state);

	    if (ret == (size_t)(-1))
	      goto bad_input2;
	    if (wc == 0)
	      {
		/* Here mbsinit (&state).  */
		break;
	      }
	    totalcount += ret;
	  }
	return totalcount;
      }

   bad_input:
    *srcp = src;
   bad_input2:
    errno = EILSEQ;
    return (size_t)(-1);
  }
}