wcsmbs/btowc.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 <ctype.h>
  19 #include <dlfcn.h>
  20 #include <gconv.h>
  21 #include <stdio.h>
  22 #include <string.h>
  23 #include <wchar.h>
  24 #include <wcsmbsload.h>
  25 #include <limits.h>
  26
  27 #include <pointer_guard.h>
  28
  29
  30 wint_t
  31 __btowc (int c)
  32 {
  33   const struct gconv_fcts *fcts;
  34
  35   /* If the parameter does not fit into one byte or it is the EOF value
  36      we can give the answer now.  */
  37   if (c < SCHAR_MIN || c > UCHAR_MAX || c == EOF)
  38     return WEOF;
  39
  40   /* We know that only ASCII compatible encodings are used for the
  41      locale and that the wide character encoding is ISO 10646.  */
  42   if (isascii (c))
  43     return (wint_t) c;
  44
  45   /* Get the conversion functions.  */
  46   fcts = get_gconv_fcts (_NL_CURRENT_DATA (LC_CTYPE));
  47   __gconv_btowc_fct btowc_fct = fcts->towc->__btowc_fct;
  48   if (fcts->towc->__shlib_handle != NULL)
  49     PTR_DEMANGLE (btowc_fct);
  50
  51   if (__builtin_expect (fcts->towc_nsteps == 1, 1)
  52       && __builtin_expect (btowc_fct != NULL, 1))
  53     {
  54       /* Use the shortcut function.  */
  55       return DL_CALL_FCT (btowc_fct, (fcts->towc, (unsigned char) c));
  56     }
  57   else
  58     {
  59       /* Fall back to the slow but generic method.  */
  60       wchar_t result;
  61       struct __gconv_step_data data;
  62       unsigned char inbuf[1];
  63       const unsigned char *inptr = inbuf;
  64       size_t dummy;
  65       int status;
  66
  67       /* Tell where we want the result.  */
  68       data.__outbuf = (unsigned char *) &result;
  69       data.__outbufend = data.__outbuf + sizeof (wchar_t);
  70       data.__invocation_counter = 0;
  71       data.__internal_use = 1;
  72       data.__flags = __GCONV_IS_LAST;
  73       data.__statep = &data.__state;
  74
  75       /* Make sure we start in the initial state.  */
  76       memset (&data.__state, '\0', sizeof (mbstate_t));
  77
  78       /* Create the input string.  */
  79       inbuf[0] = c;
  80
  81       __gconv_fct fct = fcts->towc->__fct;
  82       if (fcts->towc->__shlib_handle != NULL)
  83         PTR_DEMANGLE (fct);
  84       status = DL_CALL_FCT (fct, (fcts->towc, &data, &inptr, inptr + 1,
  85                                   NULL, &dummy, 0, 1));
  86
  87       if (status != __GCONV_OK && status != __GCONV_FULL_OUTPUT
  88           && status != __GCONV_EMPTY_INPUT)
  89         /* The conversion failed.  */
  90         result = WEOF;
  91
  92       return result;
  93     }
  94 }
  95 weak_alias (__btowc, btowc)