/* Character set conversion with error handling and autodetection.

   Copyright (C) 2002, 2005, 2007, 2009-2026 Free Software Foundation, Inc.

   Written by Bruno Haible.

   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/>.  */

#include <config.h>

/* Specification.  */

#include "striconveha.h"

#include <errno.h>

#include <stdlib.h>

#include <string.h>

#include "malloca.h"

#include "c-strcase.h"

#include "striconveh.h"

#define SIZEOF(a) (sizeof(a)/sizeof(a[0]))

/* Autodetection list.  */

struct autodetect_alias

{

  struct autodetect_alias *next;

  const char *name;

  const char * const *encodings_to_try;

};

static const char * const autodetect_utf8_try[] =

{

  /* Try UTF-8 first. There are very few ISO-8859-1 inputs that would

     be valid UTF-8, but many UTF-8 inputs are valid ISO-8859-1.  */

  "UTF-8", "ISO-8859-1",

  NULL

};

static const char * const autodetect_jp_try[] =

{

  /* Try 7-bit encoding first. If the input contains bytes >= 0x80,

     it will fail.

     Try EUC-JP next. Short SHIFT_JIS inputs may come out wrong. This

     is unavoidable. People will condemn SHIFT_JIS.

     If we tried SHIFT_JIS first, then some short EUC-JP inputs would

     come out wrong, and people would condemn EUC-JP and Unix, which

     would not be good.

     Finally try SHIFT_JIS.  */

  "ISO-2022-JP-2", "EUC-JP", "SHIFT_JIS",

  NULL

};

static const char * const autodetect_kr_try[] =

{

  /* Try 7-bit encoding first. If the input contains bytes >= 0x80,

     it will fail.

     Finally try EUC-KR.  */

  "ISO-2022-KR", "EUC-KR",

  NULL

};

static struct autodetect_alias autodetect_predefined[] =

{

  { &autodetect_predefined[1], "autodetect_utf8", autodetect_utf8_try },

  { &autodetect_predefined[2], "autodetect_jp",   autodetect_jp_try },

  { NULL,                      "autodetect_kr",   autodetect_kr_try }

};

static struct autodetect_alias *autodetect_list = &autodetect_predefined[0];

static struct autodetect_alias **autodetect_list_end =

  &autodetect_predefined[SIZEOF(autodetect_predefined)-1].next;

int

uniconv_register_autodetect (const char *name,

                             const char * const *try_in_order)

{

  /* The TRY_IN_ORDER list must not be empty.  */

  if (try_in_order[0] == NULL)

    {

      errno = EINVAL;

      return -1;

    }

  /* We must deep-copy NAME and TRY_IN_ORDER, because they may be allocated

     with dynamic extent.  */

  size_t namelen = strlen (name) + 1;

  size_t memneed = sizeof (struct autodetect_alias) + namelen + sizeof (char *);

  size_t listlen;

  {

    size_t i;

    for (i = 0; try_in_order[i] != NULL; i++)

      memneed += sizeof (char *) + strlen (try_in_order[i]) + 1;

    listlen = i;

  }

  void *memory = malloc (memneed);

  if (memory != NULL)

    {

      struct autodetect_alias *new_alias = memory;

      memory = new_alias + 1;

      char const **new_try_in_order = memory;

      memory = new_try_in_order + listlen + 1;

      char *new_name = memcpy (memory, name, namelen);

      memory = new_name + namelen;

      {

        size_t i;

        for (i = 0; i < listlen; i++)

          {

            size_t len = strlen (try_in_order[i]) + 1;

            char *copy = memcpy (memory, try_in_order[i], len);

            new_try_in_order[i] = copy;

            memory = copy + len;

          }

        new_try_in_order[i] = NULL;

      }

      /* Now insert the new alias.  */

      new_alias->name = new_name;

      new_alias->encodings_to_try = new_try_in_order;

      new_alias->next = NULL;

      /* FIXME: Not multithread-safe.  */

      *autodetect_list_end = new_alias;

      autodetect_list_end = &new_alias->next;

      return 0;

    }

  else

    {

      errno = ENOMEM;

      return -1;

    }

}

/* Like mem_iconveha, except no handling of transliteration.  */

static int

mem_iconveha_notranslit (const char *src, size_t srclen,

                         const char *from_codeset, const char *to_codeset,

                         enum iconv_ilseq_handler handler,

                         size_t *offsets,

                         char **resultp, size_t *lengthp)

{

  int retval = mem_iconveh (src, srclen, from_codeset, to_codeset, handler,

                            offsets, resultp, lengthp);

  if (retval >= 0 || errno != EINVAL)

    return retval;

  else

    {

      /* Unsupported from_codeset or to_codeset. Check whether the caller

         requested autodetection.  */

      for (struct autodetect_alias *alias = autodetect_list;

           alias != NULL;

           alias = alias->next)

        if (streq (from_codeset, alias->name))

          {

            if (handler != iconveh_error)

              {

                /* First try all encodings without any forgiving.  */

                const char * const *encodings = alias->encodings_to_try;

                do

                  {

                    retval = mem_iconveha_notranslit (src, srclen,

                                                      *encodings, to_codeset,

                                                      iconveh_error, offsets,

                                                      resultp, lengthp);

                    if (!(retval < 0 && errno == EILSEQ))

                      return retval;

                    encodings++;

                  }

                while (*encodings != NULL);

              }

            const char * const *encodings = alias->encodings_to_try;

            do

              {

                retval = mem_iconveha_notranslit (src, srclen,

                                                  *encodings, to_codeset,

                                                  handler, offsets,

                                                  resultp, lengthp);

                if (!(retval < 0 && errno == EILSEQ))

                  return retval;

                encodings++;

              }

            while (*encodings != NULL);

            /* Return the last call's result.  */

            return -1;

          }

      /* It wasn't an autodetection name.  */

      errno = EINVAL;

      return -1;

    }

}

int

mem_iconveha (const char *src, size_t srclen,

              const char *from_codeset, const char *to_codeset,

              bool transliterate,

              enum iconv_ilseq_handler handler,

              size_t *offsets,

              char **resultp, size_t *lengthp)

{

  if (srclen == 0)

    {

      /* Nothing to convert.  */

      *lengthp = 0;

      return 0;

    }

  /* When using GNU libc >= 2.2 or GNU libiconv >= 1.5 or Citrus/FreeBSD/macOS

     iconv, we want to use transliteration.  */

#if (((__GLIBC__ == 2 && __GLIBC_MINOR__ >= 2) || __GLIBC__ > 2) \

     && !defined __UCLIBC__) \

    || _LIBICONV_VERSION >= 0x0105 \

    || defined ICONV_SET_TRANSLITERATE

  if (transliterate)

    {

      size_t len = strlen (to_codeset);

      char *to_codeset_suffixed = (char *) malloca (len + 10 + 1);

      if (to_codeset_suffixed == NULL)

        {

          errno = ENOMEM;

          return -1;

        }

      memcpy (to_codeset_suffixed, to_codeset, len);

      memcpy (to_codeset_suffixed + len, "//TRANSLIT", 10 + 1);

      int retval = mem_iconveha_notranslit (src, srclen,

                                            from_codeset, to_codeset_suffixed,

                                            handler, offsets, resultp, lengthp);

      freea (to_codeset_suffixed);

      return retval;

    }

  else

#endif

    return mem_iconveha_notranslit (src, srclen,

                                    from_codeset, to_codeset,

                                    handler, offsets, resultp, lengthp);

}

/* Like str_iconveha, except no handling of transliteration.  */

static char *

str_iconveha_notranslit (const char *src,

                         const char *from_codeset, const char *to_codeset,

                         enum iconv_ilseq_handler handler)

{

  char *result = str_iconveh (src, from_codeset, to_codeset, handler);

  if (result != NULL || errno != EINVAL)

    return result;

  else

    {

      /* Unsupported from_codeset or to_codeset. Check whether the caller

         requested autodetection.  */

      for (struct autodetect_alias *alias = autodetect_list;

           alias != NULL;

           alias = alias->next)

        if (streq (from_codeset, alias->name))

          {

            if (handler != iconveh_error)

              {

                /* First try all encodings without any forgiving.  */

                const char * const *encodings = alias->encodings_to_try;

                do

                  {

                    result = str_iconveha_notranslit (src,

                                                      *encodings, to_codeset,

                                                      iconveh_error);

                    if (!(result == NULL && errno == EILSEQ))

                      return result;

                    encodings++;

                  }

                while (*encodings != NULL);

              }

            const char * const *encodings = alias->encodings_to_try;

            do

              {

                result = str_iconveha_notranslit (src,

                                                  *encodings, to_codeset,

                                                  handler);

                if (!(result == NULL && errno == EILSEQ))

                  return result;

                encodings++;

              }

            while (*encodings != NULL);

            /* Return the last call's result.  */

            return NULL;

          }

      /* It wasn't an autodetection name.  */

      errno = EINVAL;

      return NULL;

    }

}

char *

str_iconveha (const char *src,

              const char *from_codeset, const char *to_codeset,

              bool transliterate,

              enum iconv_ilseq_handler handler)

{

  if (*src == '\0' || c_strcasecmp (from_codeset, to_codeset) == 0)

    {

      char *result = strdup (src);

      if (result == NULL)

        errno = ENOMEM;

      return result;

    }

  /* When using GNU libc >= 2.2 or GNU libiconv >= 1.5 or Citrus/FreeBSD/macOS

     iconv, we want to use transliteration.  */

#if (((__GLIBC__ == 2 && __GLIBC_MINOR__ >= 2) || __GLIBC__ > 2) \

     && !defined __UCLIBC__) \

    || _LIBICONV_VERSION >= 0x0105 \

    || defined ICONV_SET_TRANSLITERATE

  if (transliterate)

    {

      size_t len = strlen (to_codeset);

      char *to_codeset_suffixed = (char *) malloca (len + 10 + 1);

      if (to_codeset_suffixed == NULL)

        {

          errno = ENOMEM;

          return NULL;

        }

      memcpy (to_codeset_suffixed, to_codeset, len);

      memcpy (to_codeset_suffixed + len, "//TRANSLIT", 10 + 1);

      char *result =

        str_iconveha_notranslit (src, from_codeset, to_codeset_suffixed,

                                 handler);

      freea (to_codeset_suffixed);

      return result;

    }

  else

#endif

    return str_iconveha_notranslit (src, from_codeset, to_codeset, handler);

}