stdlib/wcstombs.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 <localeinfo.h>
  21 #include <ctype.h>
  22 #include <stddef.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26
  27
  28 /* Convert the `wchar_t' string in PWCS to a multibyte character string
  29    in S, writing no more than N characters.  Return the number of bytes
  30    written, or (size_t) -1 if an invalid `wchar_t' was found.  */
  31 size_t
  32 DEFUN(wcstombs, (s, pwcs, n),
  33       register char *s AND register CONST wchar_t *pwcs AND register size_t n)
  34 {
  35   register CONST mb_char *mb;
  36   register int shift = 0;
  37
  38   register size_t written = 0;
  39   register wchar_t w;
  40
  41   while ((w = *pwcs++) != (wchar_t) '\0')
  42     {
  43       if (isascii (w))
  44         {
  45           /* A normal character.  */
  46           *s++ = (unsigned char) w;
  47           --n;
  48           ++written;
  49         }
  50       else
  51         {
  52           mb = &_ctype_info->mbchar->mb_chars[w + shift];
  53           if (mb->string == NULL || mb->len == 0)
  54             {
  55               written = (size_t) -1;
  56               break;
  57             }
  58           else if (mb->len > n)
  59             break;
  60           else
  61             {
  62               memcpy ((PTR) s, (CONST PTR) mb->string, mb->len);
  63               s += mb->len;
  64               n -= mb->len;
  65               written += mb->len;
  66               shift += mb->shift;
  67             }
  68         }
  69     }
  70
  71   /* Terminate the string if it has space.  */
  72   if (n > 0)
  73     *s = '\0';
  74
  75   /* Return the number of characters written (or maybe an error).  */
  76   return written;
  77 }