1  /* Copyright (C) 1996-2023 Free Software Foundation, Inc.
       2     This file is part of the GNU C Library.
       3  
       4     The GNU C Library is free software; you can redistribute it and/or
       5     modify it under the terms of the GNU Lesser General Public
       6     License as published by the Free Software Foundation; either
       7     version 2.1 of the License, or (at your option) any later version.
       8  
       9     The GNU C Library is distributed in the hope that it will be useful,
      10     but WITHOUT ANY WARRANTY; without even the implied warranty of
      11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      12     Lesser General Public License for more details.
      13  
      14     You should have received a copy of the GNU Lesser General Public
      15     License along with the GNU C Library; if not, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <assert.h>
      19  #include <dlfcn.h>
      20  #include <errno.h>
      21  #include <gconv.h>
      22  #include <wchar.h>
      23  #include <wcsmbsload.h>
      24  
      25  #include <pointer_guard.h>
      26  
      27  #ifndef EILSEQ
      28  # define EILSEQ EINVAL
      29  #endif
      30  
      31  /* This is the private state used if PS is NULL.  */
      32  static mbstate_t state;
      33  
      34  size_t
      35  __mbrtowc (wchar_t *pwc, const char *s, size_t n, mbstate_t *ps)
      36  {
      37    wchar_t buf[1];
      38    struct __gconv_step_data data;
      39    int status;
      40    size_t result;
      41    size_t dummy;
      42    const unsigned char *inbuf, *endbuf;
      43    unsigned char *outbuf = (unsigned char *) (pwc ?: buf);
      44    const struct gconv_fcts *fcts;
      45  
      46    /* Set information for this step.  */
      47    data.__invocation_counter = 0;
      48    data.__internal_use = 1;
      49    data.__flags = __GCONV_IS_LAST;
      50    data.__statep = ps ?: &state;
      51  
      52    /* A first special case is if S is NULL.  This means put PS in the
      53       initial state.  */
      54    if (s == NULL)
      55      {
      56        outbuf = (unsigned char *) buf;
      57        s = "";
      58        n = 1;
      59      }
      60  
      61    if (n == 0)
      62      return (size_t) -2;
      63  
      64    /* Tell where we want the result.  */
      65    data.__outbuf = outbuf;
      66    data.__outbufend = outbuf + sizeof (wchar_t);
      67  
      68    /* Get the conversion functions.  */
      69    fcts = get_gconv_fcts (_NL_CURRENT_DATA (LC_CTYPE));
      70  
      71    /* Do a normal conversion.  */
      72    inbuf = (const unsigned char *) s;
      73    endbuf = inbuf + n;
      74    if (__glibc_unlikely (endbuf < inbuf))
      75      {
      76        endbuf = (const unsigned char *) ~(uintptr_t) 0;
      77        if (endbuf == inbuf)
      78  	goto ilseq;
      79      }
      80    __gconv_fct fct = fcts->towc->__fct;
      81    if (fcts->towc->__shlib_handle != NULL)
      82      PTR_DEMANGLE (fct);
      83    status = DL_CALL_FCT (fct, (fcts->towc, &data, &inbuf, endbuf,
      84  			      NULL, &dummy, 0, 1));
      85  
      86    /* There must not be any problems with the conversion but illegal input
      87       characters.  The output buffer must be large enough, otherwise the
      88       definition of MB_CUR_MAX is not correct.  All the other possible
      89       errors also must not happen.  */
      90    assert (status == __GCONV_OK || status == __GCONV_EMPTY_INPUT
      91  	  || status == __GCONV_ILLEGAL_INPUT
      92  	  || status == __GCONV_INCOMPLETE_INPUT
      93  	  || status == __GCONV_FULL_OUTPUT);
      94  
      95    if (status == __GCONV_OK || status == __GCONV_EMPTY_INPUT
      96        || status == __GCONV_FULL_OUTPUT)
      97      {
      98        if (data.__outbuf != (unsigned char *) outbuf
      99  	  && *(wchar_t *) outbuf == L'\0')
     100  	{
     101  	  /* The converted character is the NUL character.  */
     102  	  assert (__mbsinit (data.__statep));
     103  	  result = 0;
     104  	}
     105        else
     106  	result = inbuf - (const unsigned char *) s;
     107      }
     108    else if (status == __GCONV_INCOMPLETE_INPUT)
     109      result = (size_t) -2;
     110    else
     111      {
     112      ilseq:
     113        result = (size_t) -1;
     114        __set_errno (EILSEQ);
     115      }
     116  
     117    return result;
     118  }
     119  libc_hidden_def (__mbrtowc)
     120  weak_alias (__mbrtowc, mbrtowc)
     121  libc_hidden_weak (mbrtowc)