/* Convert string to wide string.

   Copyright (C) 2008-2018 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 <https://www.gnu.org/licenses/>.  */

size_t

mbsrtowcs (wchar_t *dest, const char **srcp, size_t len, mbstate_t *ps)

{

  if (ps == NULL)

    ps = &_gl_mbsrtowcs_state;

  {

    const char *src = *srcp;

    if (dest != NULL)

      {

        wchar_t *destptr = dest;

        for (; len > 0; destptr++, len--)

          {

            size_t src_avail;

            size_t ret;

            /* An optimized variant of

               src_avail = strnlen1 (src, MB_LEN_MAX);  */

            if (src[0] == '\0')

              src_avail = 1;

            else if (src[1] == '\0')

              src_avail = 2;

            else if (src[2] == '\0')

              src_avail = 3;

            else if (MB_LEN_MAX <= 4 || src[3] == '\0')

              src_avail = 4;

            else

              src_avail = 4 + strnlen1 (src + 4, MB_LEN_MAX - 4);

            /* Parse the next multibyte character.  */

            ret = mbrtowc (destptr, src, src_avail, ps);

            if (ret == (size_t)(-2))

              /* Encountered a multibyte character that extends past a '\0' byte

                 or that is longer than MB_LEN_MAX bytes.  Cannot happen.  */

              abort ();

            if (ret == (size_t)(-1))

              goto bad_input;

            if (ret == 0)

              {

                src = NULL;

                /* Here mbsinit (ps).  */

                break;

              }

            src += 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 (;; totalcount++)

          {

            size_t src_avail;

            size_t ret;

            /* An optimized variant of

               src_avail = strnlen1 (src, MB_LEN_MAX);  */

            if (src[0] == '\0')

              src_avail = 1;

            else if (src[1] == '\0')

              src_avail = 2;

            else if (src[2] == '\0')

              src_avail = 3;

            else if (MB_LEN_MAX <= 4 || src[3] == '\0')

              src_avail = 4;

            else

              src_avail = 4 + strnlen1 (src + 4, MB_LEN_MAX - 4);

            /* Parse the next multibyte character.  */

            ret = mbrtowc (NULL, src, src_avail, &state);

            if (ret == (size_t)(-2))

              /* Encountered a multibyte character that extends past a '\0' byte

                 or that is longer than MB_LEN_MAX bytes.  Cannot happen.  */

              abort ();

            if (ret == (size_t)(-1))

              goto bad_input2;

            if (ret == 0)

              {

                /* Here mbsinit (&state).  */

                break;

              }

            src += ret;

          }

        return totalcount;

      }

   bad_input:

    *srcp = src;

   bad_input2:

    errno = EILSEQ;

    return (size_t)(-1);

  }

}