/* Conversion from UTF-16/UTF-32 to legacy encodings.
   Copyright (C) 2002, 2006-2017 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or
   modify it under the terms of either:

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at your
       option) any later version.

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at your
       option) any later version.

   or both in parallel, as here.
   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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

char *
FUNC (const char *tocode,
      enum iconv_ilseq_handler handler,
      const UNIT *src, size_t srclen,
      size_t *offsets,
      char *resultbuf, size_t *lengthp)
{
#if HAVE_UTF_NAME
  size_t *scaled_offsets;
  char *result;
  size_t length;

  if (offsets != NULL && srclen > 0)
    {
      scaled_offsets =
        (size_t *) malloc (srclen * sizeof (UNIT) * sizeof (size_t));
      if (scaled_offsets == NULL)
        {
          errno = ENOMEM;
          return NULL;
        }
    }
  else
    scaled_offsets = NULL;

  result = resultbuf;
  length = *lengthp;
  if (mem_iconveha ((const char *) src, srclen * sizeof (UNIT),
                    UTF_NAME, tocode,
                    handler == iconveh_question_mark, handler,
                    scaled_offsets, &result, &length) < 0)
    {
      int saved_errno = errno;
      free (scaled_offsets);
      errno = saved_errno;
      return NULL;
    }

  if (offsets != NULL)
    {
      /* Convert scaled_offsets[srclen * sizeof (UNIT)] to
         offsets[srclen].  */
      size_t i;

      for (i = 0; i < srclen; i++)
        offsets[i] = scaled_offsets[i * sizeof (UNIT)];
      free (scaled_offsets);
    }

  if (result == NULL) /* when (resultbuf == NULL && length == 0)  */
    {
      result = (char *) malloc (1);
      if (result == NULL)
        {
          errno = ENOMEM;
          return NULL;
        }
    }
  *lengthp = length;
  return result;
#else
  uint8_t tmpbuf[4096];
  size_t tmpbufsize = SIZEOF (tmpbuf);
  uint8_t *utf8_src;
  size_t utf8_srclen;
  size_t *scaled_offsets;
  char *result;

  utf8_src = U_TO_U8 (src, srclen, tmpbuf, &tmpbufsize);
  if (utf8_src == NULL)
    return NULL;
  utf8_srclen = tmpbufsize;

  if (offsets != NULL && utf8_srclen > 0)
    {
      scaled_offsets = (size_t *) malloc (utf8_srclen * sizeof (size_t));
      if (scaled_offsets == NULL)
        {
          if (utf8_src != tmpbuf)
            free (utf8_src);
          errno = ENOMEM;
          return NULL;
        }
    }
  else
    scaled_offsets = NULL;

  result = u8_conv_to_encoding (tocode, handler, utf8_src, utf8_srclen,
                                scaled_offsets, resultbuf, lengthp);
  if (result == NULL)
    {
      int saved_errno = errno;
      free (scaled_offsets);
      if (utf8_src != tmpbuf)
        free (utf8_src);
      errno = saved_errno;
      return NULL;
    }
  if (offsets != NULL)
    {
      size_t iunit;     /* offset into src */
      size_t i8;        /* offset into utf8_src */

      for (iunit = 0; iunit < srclen; iunit++)
        offsets[iunit] = (size_t)(-1);

      iunit = 0;
      i8 = 0;
      while (iunit < srclen && i8 < utf8_srclen)
        {
          int countunit;
          int count8;

          offsets[iunit] = scaled_offsets[i8];

          countunit = U_MBLEN (src + iunit, srclen - iunit);
          count8 = u8_mblen (utf8_src + i8, utf8_srclen - i8);
          if (countunit < 0 || count8 < 0)
            abort ();
          iunit += countunit;
          i8 += count8;
        }
      /* Check that utf8_src has been traversed entirely.  */
      if (i8 < utf8_srclen)
        abort ();
      /* Check that src has been traversed entirely, except possibly for an
         incomplete sequence of units at the end.  */
      if (iunit < srclen)
        {
          offsets[iunit] = *lengthp;
          if (!(U_MBLEN (src + iunit, srclen - iunit) < 0))
            abort ();
        }
      free (scaled_offsets);
    }
  if (utf8_src != tmpbuf)
    free (utf8_src);
  return result;
#endif
}