glibc/stdlib/mbtowc.c

/* Copyright (C) 1991, 1992, 1995, 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.

The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

#include <stdlib.h>
#include <wchar.h>


/* Common state for all non-restartable conversion functions.  */
mbstate_t __no_r_state;

/* Convert the multibyte character at S, which is no longer
   than N characters, to its `wchar_t' representation, placing
   this n *PWC and returning its length.

   Attention: this function should NEVER be intentionally used.
   The interface is completely stupid.  The state is shared between
   all conversion functions.  You should use instead the restartable
   version `mbrtowc'.  */
int
mbtowc (wchar_t *pwc, const char *s, size_t n)
{
  int result;

  /* If S is NULL the function has to return null or not null
     depending on the encoding having a state depending encoding or
     not.  This is nonsense because any multibyte encoding has a
     state.  The ISO C amendment 1 corrects this while introducing the
     restartable functions.  We simply say here all encodings have a
     state.  */
  if (s == NULL)
    return 1;

  result = mbrtowc (pwc, s, n, &__no_r_state);

  /* The `mbrtowc' functions tell us more than we need.  Fold the -1
     and -2 result into -1.  */
  if (result < 0)
    result = -1;

  return result;
}