/* Conversion to UTF-8 from legacy encodings.

   Copyright (C) 2002, 2006-2007, 2009-2024 Free Software Foundation, Inc.

   This file 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 2.1 of the

   License, or (at your option) any later version.

   This file 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/>.  */

/* Written by Bruno Haible <bruno@clisp.org>.  */

#include <config.h>

/* Specification.  */

#include "uniconv.h"

#include <errno.h>

#include <stdlib.h>

#include <string.h>

#include "c-strcaseeq.h"

#include "striconveha.h"

#include "unistr.h"

uint8_t *

u8_conv_from_encoding (const char *fromcode,

                       enum iconv_ilseq_handler handler,

                       const char *src, size_t srclen,

                       size_t *offsets,

                       uint8_t *resultbuf, size_t *lengthp)

{

  if (STRCASEEQ (fromcode, "UTF-8", 'U','T','F','-','8',0,0,0,0))

    {

      /* Conversion from UTF-8 to UTF-8.  No need to go through iconv().  */

      uint8_t *result;

      if (u8_check ((const uint8_t *) src, srclen))

        {

          errno = EILSEQ;

          return NULL;

        }

      if (offsets != NULL)

        {

          size_t i;

          for (i = 0; i < srclen; )

            {

              int count = u8_mblen ((const uint8_t *) src + i, srclen - i);

              /* We can rely on count > 0 because of the previous u8_check.  */

              if (count <= 0)

                abort ();

              offsets[i] = i;

              i++;

              while (--count > 0)

                offsets[i++] = (size_t)(-1);

            }

        }

      /* Memory allocation.  */

      if (resultbuf != NULL && *lengthp >= srclen)

        result = resultbuf;

      else

        {

          result = (uint8_t *) malloc (srclen > 0 ? srclen : 1);

          if (result == NULL)

            {

              errno = ENOMEM;

              return NULL;

            }

        }

      if (srclen > 0)

        memcpy ((char *) result, src, srclen);

      *lengthp = srclen;

      return result;

    }

  else

    {

      char *result = (char *) resultbuf;

      size_t length = *lengthp;

      if (mem_iconveha (src, srclen, fromcode, "UTF-8", true, handler,

                        offsets, &result, &length) < 0)

        return NULL;

      if (result == NULL) /* when (resultbuf == NULL && length == 0)  */

        {

          result = (char *) malloc (1);

          if (result == NULL)

            {

              errno = ENOMEM;

              return NULL;

            }

        }

      *lengthp = length;

      return (uint8_t *) result;

    }

}