stdlib/mbtowc.c

   1 /* Copyright (C) 1991, 1992, 1995, 1996, 1997 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
  22
  23 /* Common state for all non-restartable conversion functions.  */
  24 mbstate_t __no_r_state;
  25
  26 /* Convert the multibyte character at S, which is no longer
  27    than N characters, to its `wchar_t' representation, placing
  28    this n *PWC and returning its length.
  29
  30    Attention: this function should NEVER be intentionally used.
  31    The interface is completely stupid.  The state is shared between
  32    all conversion functions.  You should use instead the restartable
  33    version `mbrtowc'.  */
  34 int
  35 mbtowc (wchar_t *pwc, const char *s, size_t n)
  36 {
  37   int result;
  38
  39   /* If S is NULL the function has to return null or not null
  40      depending on the encoding having a state depending encoding or
  41      not.  This is nonsense because any multibyte encoding has a
  42      state.  The ISO C amendment 1 corrects this while introducing the
  43      restartable functions.  We simply say here all encodings have a
  44      state.  */
  45   if (s == NULL)
  46     return 1;
  47
  48   result = __mbrtowc (pwc, s, n, &__no_r_state);
  49
  50   /* The `mbrtowc' functions tell us more than we need.  Fold the -1
  51      and -2 result into -1.  */
  52   if (result < 0)
  53     result = -1;
  54
  55   return result;
  56 }