text: /* Convert UTF-16 string to UTF-8 string.
     Copyright (C) 2002, 2006-2007, 2009-2012 Free Software Foundation, Inc.
     Written by Bruno Haible <bruno@clisp.org>, 2002.
  
     This program is free software: you can redistribute it and/or modify it
     under the terms of 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.
  
     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 <http://www.gnu.org/licenses/>.  */
  
  #include <config.h>
  
  /* Specification.  */
  #include "unistr.h"
  
  #define FUNC u16_to_u8
  #define SRC_UNIT uint16_t
  #define DST_UNIT uint8_t
  
  #include <errno.h>
  #include <stdlib.h>
  #include <string.h>
  
  DST_UNIT *
  FUNC (const SRC_UNIT *s, size_t n, DST_UNIT *resultbuf, size_t *lengthp)
  {
    const SRC_UNIT *s_end = s + n;
    /* Output string accumulator.  */
    DST_UNIT *result;
    size_t allocated;
    size_t length;
  
    if (resultbuf != NULL)
      {
        result = resultbuf;
        allocated = *lengthp;
      }
    else
      {
        result = NULL;
        allocated = 0;
      }
    length = 0;
    /* Invariants:
       result is either == resultbuf or == NULL or malloc-allocated.
       If length > 0, then result != NULL.  */
  
    while (s < s_end)
      {
        ucs4_t uc;
        int count;
  
        /* Fetch a Unicode character from the input string.  */
        count = u16_mbtoucr (&uc, s, s_end - s);
        if (count < 0)
          {
            if (!(result == resultbuf || result == NULL))
              free (result);
            errno = EILSEQ;
            return NULL;
          }
        s += count;
  
        /* Store it in the output string.  */
        count = u8_uctomb (result + length, uc, allocated - length);
        if (count == -1)
          {
            if (!(result == resultbuf || result == NULL))
              free (result);
            errno = EILSEQ;
            return NULL;
          }
        if (count == -2)
          {
            DST_UNIT *memory;
  
            allocated = (allocated > 0 ? 2 * allocated : 12);
            if (length + 6 > allocated)
              allocated = length + 6;
            if (result == resultbuf || result == NULL)
              memory = (DST_UNIT *) malloc (allocated * sizeof (DST_UNIT));
            else
              memory =
                (DST_UNIT *) realloc (result, allocated * sizeof (DST_UNIT));
  
            if (memory == NULL)
              {
                if (!(result == resultbuf || result == NULL))
                  free (result);
                errno = ENOMEM;
                return NULL;
              }
            if (result == resultbuf && length > 0)
              memcpy ((char *) memory, (char *) result,
                      length * sizeof (DST_UNIT));
            result = memory;
            count = u8_uctomb (result + length, uc, allocated - length);
            if (count < 0)
              abort ();
          }
        length += count;
      }
  
    if (length == 0)
      {
        if (result == NULL)
          {
            /* Return a non-NULL value.  NULL means error.  */
            result = (DST_UNIT *) malloc (1);
            if (result == NULL)
              {
                errno = ENOMEM;
                return NULL;
              }
          }
      }
    else if (result != resultbuf && length < allocated)
      {
        /* Shrink the allocated memory if possible.  */
        DST_UNIT *memory;
  
        memory = (DST_UNIT *) realloc (result, length * sizeof (DST_UNIT));
        if (memory != NULL)
          result = memory;
      }
  
    *lengthp = length;
    return result;
  }
  