/* Convert multibyte character to wide character.

   Copyright (C) 1999-2002, 2005-2026 Free Software Foundation, Inc.

   Written by Bruno Haible <bruno@clisp.org>, 2008.

   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 <wchar.h>

#if GNULIB_defined_mbstate_t

/* Implement mbrtowc() on top of mbtowc() for the non-UTF-8 locales

   and directly for the UTF-8 locales.  */

# include <errno.h>

# include <stdint.h>

# include <stdlib.h>

# if AVOID_ANY_THREADS

/* The option '--disable-threads' explicitly requests no locking.  */

# elif defined _WIN32 && !defined __CYGWIN__

#  define WIN32_LEAN_AND_MEAN  /* avoid including junk */

#  include <windows.h>

# elif HAVE_PTHREAD_API

#  include <pthread.h>

#  if HAVE_THREADS_H && HAVE_WEAK_SYMBOLS

#   include <threads.h>

#   pragma weak thrd_exit

#   define c11_threads_in_use() (thrd_exit != NULL)

#  else

#   define c11_threads_in_use() 0

#  endif

# elif HAVE_THREADS_H

#  include <threads.h>

# endif

# include "attribute.h"

# include "lc-charset-dispatch.h"

# include "mbtowc-lock.h"

static_assert (sizeof (mbstate_t) >= 4);

static char internal_state[4];

size_t

mbrtowc (wchar_t *pwc, const char *s, size_t n, mbstate_t *ps)

{

# define FITS_IN_CHAR_TYPE(wc)  ((wc) <= WCHAR_MAX)

# include "mbrtowc-impl.h"

}

#else

/* Override the system's mbrtowc() function.  */

# include <errno.h>

# include <stdlib.h>

# include "attribute.h"

# include "localcharset.h"

# include "streq-opt.h"

# if MBRTOWC_IN_C_LOCALE_MAYBE_EILSEQ

#  include "hard-locale.h"

#  include <locale.h>

# endif

# if MBRTOWC_INVALID_UTF8_BUG || (GNULIB_WCHAR_SINGLE_LOCALE && __GLIBC__ >= 2 && !__UCLIBC__)

/* Returns 1 if the current locale is an UTF-8 locale, 0 otherwise.  */

static inline int

is_locale_utf8 (void)

{

  const char *encoding = locale_charset ();

  return STREQ_OPT (encoding, "UTF-8", 'U', 'T', 'F', '-', '8', 0, 0, 0, 0);

}

/* Provide a speedup by caching the value of is_locale_utf8.  */

static int cached_is_locale_utf8 = -1;

static inline int

is_locale_utf8_cached (void)

{

  if (cached_is_locale_utf8 < 0)

    cached_is_locale_utf8 = is_locale_utf8 ();

  return cached_is_locale_utf8;

}

# endif

# undef mbrtowc

size_t

rpl_mbrtowc (wchar_t *pwc, const char *s, size_t n, mbstate_t *ps)

{

  /* It's simpler to handle the case s == NULL upfront, than to worry about

     this case later, before every test of pwc and n.  */

  if (s == NULL)

    {

      pwc = NULL;

      s = "";

      n = 1;

    }

# if (MBRTOWC_EMPTY_INPUT_BUG || MBRTOWC_INVALID_UTF8_BUG \

      || (GNULIB_WCHAR_SINGLE_LOCALE && __GLIBC__ >= 2 && !__UCLIBC__))

  if (n == 0)

    return (size_t) -2;

# endif

# if MBRTOWC_INVALID_UTF8_BUG || (GNULIB_WCHAR_SINGLE_LOCALE && __GLIBC__ >= 2 && !__UCLIBC__)

  /* Optimize the frequent case of an UTF-8 locale.

     Since here we are in the !GNULIB_defined_mbstate_t case, i.e. we use

     the system's mbstate_t type and have to provide interoperability with

     the system's mbsinit() function, this requires knowledge about how the

     system's UTF-8 mbrtowc() function stores the state.  This knowledge is

     platform-specific.  For simplicity, we handle only glibc and NetBSD

     systems.  */

  if (is_locale_utf8_cached ())

    {

      static mbstate_t internal_state;

      if (ps == NULL)

        ps = &internal_state;

      #if __GLIBC__ >= 2

      /* Structure of mbstate_t =

         { int __count; union { wint_t __wch; char __wchb[4]; } __value; }

         (see glibc/iconv/gconv_simple.c function utf8_internal_loop):

         Bits 2..0 of __count is the number of input bytes already consumed.

         Bits 31..8 of __count is the number of input bytes expected for the

         entire byte sequence.

         __value.__wch is the already inferrable bits of the character, of

         the form (x << (r*6)) when r bytes are still expected.  */

      #endif

      #ifdef __NetBSD__

      /* Structure of mbstate_t =

         union { int64_t __mbstateL; char __mbstate8[128]; }

         (see src/lib/libc/citrus/modules/citrus_utf8.c):

         { void *header; char ch[6]; int chlen; },

         i.e. ch[0..5] is __mbstate8[sizeof(void*)+0..sizeof(void*)+5],

              chlen is __mbstate8[sizeof(void*)+8..sizeof(void*)+11].  */

      #endif

      /* Here n > 0.  */

      size_t nstate;

      #if __GLIBC__ >= 2

      nstate = ps->__count & 7;

      #endif

      #ifdef __NetBSD__

      nstate = *(int *) &ps->__mbstate8[sizeof (void *) + 8];

      #endif

      char buf[4];

      const char *p;

      size_t m;

      if (nstate == 0)

        {

          p = s;

          m = n;

        }

      else

        {

          #if __GLIBC__ >= 2

          size_t t = ps->__count >> 8; /* total expected number of bytes */

          if (t > nstate && t <= 4)

            {

              buf[0] =

                (0x100 - (0x100 >> t)) | (ps->__value.__wch >> ((t - 1) * 6));

              if (nstate >= 2)

                {

                  buf[1] =

                    0x80 | ((ps->__value.__wch >> ((t - 2) * 6)) & 0x3F);

                  if (nstate >= 3)

                    {

                      buf[2] =

                        0x80 | ((ps->__value.__wch >> ((t - 3) * 6)) & 0x3F);

                    }

                }

            }

          else

            {

              errno = EINVAL;

              return (size_t)(-1);

            }

          #endif

          #ifdef __NetBSD__

          buf[0] = ps->__mbstate8[sizeof (void *) + 0];

          if (nstate >= 2)

            {

              buf[1] = ps->__mbstate8[sizeof (void *) + 1];

              if (nstate >= 3)

                {

                  buf[2] = ps->__mbstate8[sizeof (void *) + 2];

                }

            }

          #endif

          p = buf;

          m = nstate;

          buf[m++] = s[0];

          if (n >= 2 && m < 4)

            {

              buf[m++] = s[1];

              if (n >= 3 && m < 4)

                buf[m++] = s[2];

            }

        }

      /* Here m > 0.  */

      int res;

      {

#  define FITS_IN_CHAR_TYPE(wc)  ((wc) <= WCHAR_MAX)

#  include "mbrtowc-impl-utf8.h"

      }

     success:

      /* res >= 0 is the corrected return value of

         mbtowc_with_lock (&wc, p, m).  */

      if (nstate >= (res > 0 ? res : 1))

        abort ();

      res -= nstate;

      #if __GLIBC__ >= 2

      ps->__count = 0;

      #endif

      #ifdef __NetBSD__

      *(int *) &ps->__mbstate8[sizeof (void *) + 8] = 0;

      #endif

      return res;

     incomplete:

      /* Here 0 < m < 4.  */

      {

        #if __GLIBC__ >= 2

        unsigned char c = (unsigned char) p[0];

        if (c < 0xE0)

          {

            ps->__count = (2 << 8) | m;

            ps->__value.__wch = (c & 0x1F) << 6;

          }

        else if (c < 0xF0)

          {

            ps->__count = (3 << 8) | m;

            ps->__value.__wch =

              ((c & 0x0F) << 12)

              | (m > 1 ? ((unsigned char) p[1] & 0x3F) << 6 : 0);

          }

        else

          {

            ps->__count = (4 << 8) | m;

            ps->__value.__wch =

              ((c & 0x07) << 18)

              | (m > 1 ? ((unsigned char) p[1] & 0x3F) << 12 : 0)

              | (m > 2 ? ((unsigned char) p[2] & 0x3F) << 6 : 0);

          }

        #endif

        #ifdef __NetBSD__

        *(int *) &ps->__mbstate8[sizeof (void *) + 8] = m;

        ps->__mbstate8[sizeof (void *) + 0] = p[0];

        if (m > 1)

          {

            ps->__mbstate8[sizeof (void *) + 1] = p[1];

            if (m > 2)

              {

                ps->__mbstate8[sizeof (void *) + 2] = p[2];

              }

          }

        #endif

      }

      return (size_t)(-2);

     invalid:

      errno = EILSEQ;

      /* The conversion state is undefined, says POSIX.  */

      return (size_t)(-1);

    }

# endif

  wchar_t wc;

  if (! pwc)

    pwc = &wc;

# if MBRTOWC_RETVAL_BUG

  {

    static mbstate_t internal_state;

    /* Override mbrtowc's internal state.  We cannot call mbsinit() on the

       hidden internal state, but we can call it on our variable.  */

    if (ps == NULL)

      ps = &internal_state;

    if (!mbsinit (ps))

      {

        /* Parse the rest of the multibyte character byte for byte.  */

        size_t count = 0;

        for (; n > 0; s++, n--)

          {

            size_t ret = mbrtowc (&wc, s, 1, ps);

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

              return (size_t)(-1);

            count++;

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

              {

                /* The multibyte character has been completed.  */

                *pwc = wc;

                return (wc == 0 ? 0 : count);

              }

          }

        return (size_t)(-2);

      }

  }

# endif

  size_t ret;

# if MBRTOWC_STORES_INCOMPLETE_BUG

  ret = mbrtowc (&wc, s, n, ps);

  if (ret < (size_t) -2 && pwc != NULL)

    *pwc = wc;

# else

  ret = mbrtowc (pwc, s, n, ps);

# endif

# if MBRTOWC_NUL_RETVAL_BUG

  if (ret < (size_t) -2 && !*pwc)

    return 0;

# endif

# if MBRTOWC_IN_C_LOCALE_MAYBE_EILSEQ

  if ((size_t) -2 <= ret && n != 0 && ! hard_locale (LC_CTYPE))

    {

      unsigned char uc = *s;

      *pwc = uc;

      return 1;

    }

# endif

  return ret;

}

#endif