1  /* Test for initial conversion state.
       2     Copyright (C) 2008-2021 Free Software Foundation, Inc.
       3     Written by Bruno Haible <bruno@clisp.org>, 2008.
       4  
       5     This program is free software: you can redistribute it and/or modify
       6     it under the terms of the GNU General Public License as published by
       7     the Free Software Foundation; either version 3 of the License, or
       8     (at your option) any later version.
       9  
      10     This program is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      13     GNU General Public License for more details.
      14  
      15     You should have received a copy of the GNU General Public License
      16     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <config.h>
      19  
      20  /* Specification.  */
      21  #include <wchar.h>
      22  
      23  #include "verify.h"
      24  
      25  #if GNULIB_defined_mbstate_t
      26  
      27  /* Platforms that lack mbsinit() also lack mbrlen(), mbrtowc(), mbsrtowcs()
      28     and wcrtomb(), wcsrtombs().
      29     We assume that
      30       - sizeof (mbstate_t) >= 4,
      31       - only stateless encodings are supported (such as UTF-8 and EUC-JP, but
      32         not ISO-2022 variants),
      33       - for each encoding, the number of bytes for a wide character is <= 4.
      34         (This maximum is attained for UTF-8, GB18030, EUC-TW.)
      35     We define the meaning of mbstate_t as follows:
      36       - In mb -> wc direction, mbstate_t's first byte contains the number of
      37         buffered bytes (in the range 0..3), followed by up to 3 buffered bytes.
      38         See mbrtowc.c.
      39       - In wc -> mb direction, mbstate_t contains no information. In other
      40         words, it is always in the initial state.  */
      41  
      42  verify (sizeof (mbstate_t) >= 4);
      43  
      44  int
      45  mbsinit (const mbstate_t *ps)
      46  {
      47    const char *pstate = (const char *)ps;
      48  
      49    return pstate == NULL || pstate[0] == 0;
      50  }
      51  
      52  #else
      53  
      54  int
      55  mbsinit (const mbstate_t *ps)
      56  {
      57  # if defined _WIN32 && !defined __CYGWIN__
      58    /* Native Windows.  */
      59    /* MSVC defines 'mbstate_t' as an 8-byte struct; the first 4 bytes matter.
      60       On mingw, 'mbstate_t' is sometimes defined as 'int', sometimes defined as
      61       an 8-byte struct, of which the first 4 bytes matter.  */
      62    return ps == NULL || *(const unsigned int *)ps == 0;
      63  # else
      64    /* Minix, HP-UX 11.00, Solaris 2.6, Interix, ...  */
      65    /* Maybe this definition works, maybe not...  */
      66    return ps == NULL || *(const char *)ps == 0;
      67  # endif
      68  }
      69  
      70  #endif