wcsmbs/wctob.c

   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 <dlfcn.h>
  19 #include <gconv.h>
  20 #include <stdio.h>
  21 #include <string.h>
  22 #include <wchar.h>
  23 #include <wcsmbsload.h>
  24
  25 #include <pointer_guard.h>
  26
  27
  28 int
  29 wctob (wint_t c)
  30 {
  31   unsigned char buf[MB_LEN_MAX];
  32   struct __gconv_step_data data;
  33   wchar_t inbuf[1];
  34   wchar_t *inptr = inbuf;
  35   size_t dummy;
  36   int status;
  37   const struct gconv_fcts *fcts;
  38
  39   if (c == WEOF)
  40     return EOF;
  41
  42   /* We know that only ASCII compatible encodings are used for the
  43      locale and that the wide character encoding is ISO 10646.  */
  44   if (c >= L'\0' && c <= L'\x7f')
  45     return (int) c;
  46
  47   /* Tell where we want the result.  */
  48   data.__outbuf = buf;
  49   data.__outbufend = buf + MB_LEN_MAX;
  50   data.__invocation_counter = 0;
  51   data.__internal_use = 1;
  52   data.__flags = __GCONV_IS_LAST;
  53   data.__statep = &data.__state;
  54
  55   /* Make sure we start in the initial state.  */
  56   memset (&data.__state, '\0', sizeof (mbstate_t));
  57
  58   /* Get the conversion functions.  */
  59   fcts = get_gconv_fcts (_NL_CURRENT_DATA (LC_CTYPE));
  60
  61   /* Create the input string.  */
  62   inbuf[0] = c;
  63
  64   const unsigned char *argptr = (const unsigned char *) inptr;
  65   __gconv_fct fct = fcts->tomb->__fct;
  66   if (fcts->tomb->__shlib_handle != NULL)
  67     PTR_DEMANGLE (fct);
  68   status = DL_CALL_FCT (fct,
  69                         (fcts->tomb, &data, &argptr,
  70                          argptr + sizeof (inbuf[0]), NULL, &dummy, 0, 1));
  71
  72   /* The conversion failed or the output is too long.  */
  73   if ((status != __GCONV_OK && status != __GCONV_FULL_OUTPUT
  74        && status != __GCONV_EMPTY_INPUT)
  75       || data.__outbuf != (unsigned char *) (buf + 1))
  76     return EOF;
  77
  78   return buf[0];
  79 }