stdlib/mbstowcs.c

   1 /* Copyright (C) 1991, 1992 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
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <ansidecl.h>
  20 #include <ctype.h>
  21 #include <stddef.h>
  22 #include <stdlib.h>
  23
  24
  25 extern int _mb_shift;   /* Defined in mbtowc.c.  */
  26
  27 /* Convert the string of multibyte characters in S to `wchar_t's in
  28    PWCS, writing no more than N.  Return the number written,
  29    or (size_t) -1 if an invalid multibyte character is encountered.  */
  30 size_t
  31 DEFUN(mbstowcs, (pwcs, s, n),
  32       register wchar_t *pwcs AND register CONST char *s AND register size_t n)
  33 {
  34   int save_shift;
  35   register size_t written = 0;
  36
  37   /* Save the shift state.  */
  38   save_shift = _mb_shift;
  39   /* Reset the shift state.  */
  40   _mb_shift = 0;
  41
  42   while (*s != '\0')
  43     {
  44       int len;
  45       if (isascii (*s))
  46         {
  47           *pwcs = (wchar_t) *s;
  48           len = 1;
  49         }
  50       else
  51         len = mbtowc (pwcs, s, n);
  52
  53       if (len < 1)
  54         {
  55           /* Return an error.  */
  56           written = (size_t) -1;
  57           break;
  58         }
  59       else
  60         {
  61           /* Multibyte character converted.  */
  62           ++pwcs;
  63           ++written;
  64           s += len;
  65           n -= len;
  66         }
  67     }
  68
  69   /* Terminate the string if it has space.  */
  70   if (n > 0)
  71     *pwcs = (wchar_t) 0;
  72
  73   /* Restore the old shift state.  */
  74   _mb_shift = save_shift;
  75
  76   /* Return how many we wrote (or maybe an error).  */
  77   return written;
  78 }