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 <string.h>
      23  #include <wchar.h>
      24  #include <wcsmbsload.h>
      25  
      26  #include <pointer_guard.h>
      27  
      28  #ifndef EILSEQ
      29  # define EILSEQ EINVAL
      30  #endif
      31  
      32  
      33  /* This is the private state used if PS is NULL.  */
      34  static mbstate_t state;
      35  
      36  /* This is a non-standard function but it is very useful in the
      37     implementation of stdio because we have to deal with unterminated
      38     buffers.  At most NMC bytes will be converted.  */
      39  size_t
      40  __mbsnrtowcs (wchar_t *dst, const char **src, size_t nmc, size_t len,
      41  	      mbstate_t *ps)
      42  {
      43    const unsigned char *srcend;
      44    struct __gconv_step_data data;
      45    size_t result;
      46    int status;
      47    struct __gconv_step *towc;
      48    size_t dummy;
      49    const struct gconv_fcts *fcts;
      50  
      51    /* Tell where we want the result.  */
      52    data.__invocation_counter = 0;
      53    data.__internal_use = 1;
      54    data.__flags = __GCONV_IS_LAST;
      55    data.__statep = ps ?: &state;
      56  
      57    if (nmc == 0)
      58      return 0;
      59    srcend = (const unsigned char *) *src + __strnlen (*src, nmc - 1) + 1;
      60  
      61    /* Get the conversion functions.  */
      62    fcts = get_gconv_fcts (_NL_CURRENT_DATA (LC_CTYPE));
      63  
      64    /* Get the structure with the function pointers.  */
      65    towc = fcts->towc;
      66    __gconv_fct fct = towc->__fct;
      67    if (towc->__shlib_handle != NULL)
      68      PTR_DEMANGLE (fct);
      69  
      70    /* We have to handle DST == NULL special.  */
      71    if (dst == NULL)
      72      {
      73        mbstate_t temp_state;
      74        wchar_t buf[64];		/* Just an arbitrary size.  */
      75        const unsigned char *inbuf = (const unsigned char *) *src;
      76  
      77        temp_state = *data.__statep;
      78        data.__statep = &temp_state;
      79  
      80        result = 0;
      81        data.__outbufend = (unsigned char *) buf + sizeof (buf);
      82        do
      83  	{
      84  	  data.__outbuf = (unsigned char *) buf;
      85  
      86  	  status = DL_CALL_FCT (fct, (towc, &data, &inbuf, srcend, NULL,
      87  				      &dummy, 0, 1));
      88  
      89  	  result += (wchar_t *) data.__outbuf - buf;
      90  	}
      91        while (status == __GCONV_FULL_OUTPUT);
      92  
      93        if ((status == __GCONV_OK || status == __GCONV_EMPTY_INPUT)
      94  	  && ((wchar_t *) data.__outbuf)[-1] == L'\0')
      95  	/* Don't count the NUL character in.  */
      96  	--result;
      97      }
      98    else
      99      {
     100        /* This code is based on the safe assumption that all internal
     101  	 multi-byte encodings use the NUL byte only to mark the end
     102  	 of the string.  */
     103        data.__outbuf = (unsigned char *) dst;
     104        data.__outbufend = data.__outbuf + len * sizeof (wchar_t);
     105  
     106        status = DL_CALL_FCT (fct,
     107  			    (towc, &data, (const unsigned char **) src, srcend,
     108  			     NULL, &dummy, 0, 1));
     109  
     110        result = (wchar_t *) data.__outbuf - dst;
     111  
     112        /* We have to determine whether the last character converted
     113  	 is the NUL character.  */
     114        if ((status == __GCONV_OK || status == __GCONV_EMPTY_INPUT)
     115  	  && (assert (result > 0),
     116  	      ((wchar_t *) dst)[result - 1] == L'\0'))
     117  	{
     118  	  assert (__mbsinit (data.__statep));
     119  	  *src = NULL;
     120  	  --result;
     121  	}
     122      }
     123  
     124    /* There must not be any problems with the conversion but illegal input
     125       characters.  */
     126    assert (status == __GCONV_OK || status == __GCONV_EMPTY_INPUT
     127  	  || status == __GCONV_ILLEGAL_INPUT
     128  	  || status == __GCONV_INCOMPLETE_INPUT
     129  	  || status == __GCONV_FULL_OUTPUT);
     130  
     131    if (status != __GCONV_OK && status != __GCONV_FULL_OUTPUT
     132        && status != __GCONV_EMPTY_INPUT && status != __GCONV_INCOMPLETE_INPUT)
     133      {
     134        result = (size_t) -1;
     135        __set_errno (EILSEQ);
     136      }
     137  
     138    return result;
     139  }
     140  weak_alias (__mbsnrtowcs, mbsnrtowcs)