wcsmbs/btowc.c

   1 /* Copyright (C) 1996-2017 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@gnu.org>, 1996.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <ctype.h>
  20 #include <dlfcn.h>
  21 #include <gconv.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24 #include <wchar.h>
  25 #include <wcsmbsload.h>
  26 #include <limits.h>
  27
  28 #include <sysdep.h>
  29
  30
  31 wint_t
  32 __btowc (int c)
  33 {
  34   const struct gconv_fcts *fcts;
  35
  36   /* If the parameter does not fit into one byte or it is the EOF value
  37      we can give the answer now.  */
  38   if (c < SCHAR_MIN || c > UCHAR_MAX || c == EOF)
  39     return WEOF;
  40
  41   /* We know that only ASCII compatible encodings are used for the
  42      locale and that the wide character encoding is ISO 10646.  */
  43   if (isascii (c))
  44     return (wint_t) c;
  45
  46   /* Get the conversion functions.  */
  47   fcts = get_gconv_fcts (_NL_CURRENT_DATA (LC_CTYPE));
  48   __gconv_btowc_fct btowc_fct = fcts->towc->__btowc_fct;
  49 #ifdef PTR_DEMANGLE
  50   if (fcts->towc->__shlib_handle != NULL)
  51     PTR_DEMANGLE (btowc_fct);
  52 #endif
  53
  54   if (__builtin_expect (fcts->towc_nsteps == 1, 1)
  55       && __builtin_expect (btowc_fct != NULL, 1))
  56     {
  57       /* Use the shortcut function.  */
  58       return DL_CALL_FCT (btowc_fct, (fcts->towc, (unsigned char) c));
  59     }
  60   else
  61     {
  62       /* Fall back to the slow but generic method.  */
  63       wchar_t result;
  64       struct __gconv_step_data data;
  65       unsigned char inbuf[1];
  66       const unsigned char *inptr = inbuf;
  67       size_t dummy;
  68       int status;
  69
  70       /* Tell where we want the result.  */
  71       data.__outbuf = (unsigned char *) &result;
  72       data.__outbufend = data.__outbuf + sizeof (wchar_t);
  73       data.__invocation_counter = 0;
  74       data.__internal_use = 1;
  75       data.__flags = __GCONV_IS_LAST;
  76       data.__statep = &data.__state;
  77
  78       /* Make sure we start in the initial state.  */
  79       memset (&data.__state, '\0', sizeof (mbstate_t));
  80
  81       /* Create the input string.  */
  82       inbuf[0] = c;
  83
  84       __gconv_fct fct = fcts->towc->__fct;
  85 #ifdef PTR_DEMANGLE
  86       if (fcts->towc->__shlib_handle != NULL)
  87         PTR_DEMANGLE (fct);
  88 #endif
  89       status = DL_CALL_FCT (fct, (fcts->towc, &data, &inptr, inptr + 1,
  90                                   NULL, &dummy, 0, 1));
  91
  92       if (status != __GCONV_OK && status != __GCONV_FULL_OUTPUT
  93           && status != __GCONV_EMPTY_INPUT)
  94         /* The conversion failed.  */
  95         result = WEOF;
  96
  97       return result;
  98     }
  99 }
 100 weak_alias (__btowc, btowc)