wcsmbs/wcsnrtombs.c

   1 /* Copyright (C) 1996-2024 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
  32 /* This is the private state used if PS is NULL.  */
  33 static mbstate_t state;
  34
  35 /* This is a non-standard function but it is very useful in the
  36    implementation of stdio because we have to deal with unterminated
  37    buffers.  At most NWC wide character will be converted.  */
  38 size_t
  39 __wcsnrtombs (char *dst, const wchar_t **src, size_t nwc, size_t len,
  40               mbstate_t *ps)
  41 {
  42   struct __gconv_step_data data;
  43   const wchar_t *srcend;
  44   int status;
  45   size_t result;
  46   struct __gconv_step *tomb;
  47   const struct gconv_fcts *fcts;
  48
  49   /* Tell where we want the result.  */
  50   data.__invocation_counter = 0;
  51   data.__internal_use = 1;
  52   data.__flags = __GCONV_IS_LAST;
  53   data.__statep = ps ?: &state;
  54
  55   if (nwc == 0)
  56     return 0;
  57   srcend = *src + __wcsnlen (*src, nwc - 1) + 1;
  58
  59   /* Get the conversion functions.  */
  60   fcts = get_gconv_fcts (_NL_CURRENT_DATA (LC_CTYPE));
  61
  62   /* Get the structure with the function pointers.  */
  63   tomb = fcts->tomb;
  64   __gconv_fct fct = tomb->__fct;
  65   if (tomb->__shlib_handle != NULL)
  66     PTR_DEMANGLE (fct);
  67
  68   /* We have to handle DST == NULL special.  */
  69   if (dst == NULL)
  70     {
  71       mbstate_t temp_state;
  72       unsigned char buf[256];           /* Just an arbitrary value.  */
  73       const unsigned char *inbuf = (const unsigned char *) *src;
  74       size_t dummy;
  75
  76       temp_state = *data.__statep;
  77       data.__statep = &temp_state;
  78
  79       result = 0;
  80       data.__outbufend = buf + sizeof (buf);
  81
  82       do
  83         {
  84           data.__outbuf = buf;
  85
  86           status = DL_CALL_FCT (fct, (tomb, &data, &inbuf,
  87                                       (const unsigned char *) srcend, NULL,
  88                                       &dummy, 0, 1));
  89
  90           /* Count the number of bytes.  */
  91           result += data.__outbuf - buf;
  92         }
  93       while (status == __GCONV_FULL_OUTPUT);
  94
  95       if ((status == __GCONV_OK || status == __GCONV_EMPTY_INPUT)
  96           && data.__outbuf[-1] == '\0')
  97         /* Don't count the NUL character in.  */
  98         --result;
  99     }
 100   else
 101     {
 102       /* This code is based on the safe assumption that all internal
 103          multi-byte encodings use the NUL byte only to mark the end
 104          of the string.  */
 105       size_t dummy;
 106
 107       data.__outbuf = (unsigned char *) dst;
 108       data.__outbufend = (unsigned char *) dst + len;
 109
 110       status = DL_CALL_FCT (fct, (tomb, &data, (const unsigned char **) src,
 111                                   (const unsigned char *) srcend, NULL,
 112                                   &dummy, 0, 1));
 113
 114       /* Count the number of bytes.  */
 115       result = data.__outbuf - (unsigned char *) dst;
 116
 117       /* We have to determine whether the last character converted
 118          is the NUL character.  */
 119       if ((status == __GCONV_OK || status == __GCONV_EMPTY_INPUT)
 120           && data.__outbuf[-1] == '\0')
 121         {
 122           assert (data.__outbuf != (unsigned char *) dst);
 123           assert (__mbsinit (data.__statep));
 124           *src = NULL;
 125           --result;
 126         }
 127     }
 128
 129   /* There must not be any problems with the conversion but illegal input
 130      characters.  */
 131   assert (status == __GCONV_OK || status == __GCONV_EMPTY_INPUT
 132           || status == __GCONV_ILLEGAL_INPUT
 133           || status == __GCONV_INCOMPLETE_INPUT
 134           || status == __GCONV_FULL_OUTPUT);
 135
 136   if (status != __GCONV_OK && status != __GCONV_FULL_OUTPUT
 137       && status != __GCONV_EMPTY_INPUT)
 138     {
 139       result = (size_t) -1;
 140       __set_errno (EILSEQ);
 141     }
 142
 143   return result;
 144 }
 145 weak_alias (__wcsnrtombs, wcsnrtombs)