stdlib/mbtowc.c

   1 /* Copyright (C) 1991, 92, 95, 96, 97, 98 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 Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    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    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <stdlib.h>
  20 #include <wchar.h>
  21 #include <gconv.h>
  22 #include <wcsmbs/wcsmbsload.h>
  23
  24
  25 /* Common state for all non-restartable conversion functions.  */
  26 mbstate_t __no_r_state;
  27
  28 /* Convert the multibyte character at S, which is no longer
  29    than N characters, to its `wchar_t' representation, placing
  30    this n *PWC and returning its length.
  31
  32    Attention: this function should NEVER be intentionally used.
  33    The interface is completely stupid.  The state is shared between
  34    all conversion functions.  You should use instead the restartable
  35    version `mbrtowc'.  */
  36 int
  37 mbtowc (wchar_t *pwc, const char *s, size_t n)
  38 {
  39   int result;
  40
  41   /* If S is NULL the function has to return null or not null
  42      depending on the encoding having a state depending encoding or
  43      not.  */
  44   if (s == NULL)
  45     {
  46       /* Make sure we use the correct value.  */
  47       update_conversion_ptrs ();
  48
  49       result = __wcsmbs_gconv_fcts.towc->stateful;
  50     }
  51   else if (*s == '\0')
  52     {
  53       if (pwc != NULL)
  54         *pwc = L'\0';
  55       result = 0;
  56     }
  57   else
  58     {
  59       result = __mbrtowc (pwc, s, n, &__no_r_state);
  60
  61       /* The `mbrtowc' functions tell us more than we need.  Fold the -1
  62          and -2 result into -1.  */
  63       if (result < 0)
  64         result = -1;
  65     }
  66
  67   return result;
  68 }