lib/libc/stdio/ungetwc.c

   1 /* $NetBSD: ungetwc.c,v 1.2 2003/01/18 11:29:59 thorpej Exp $ */
   2
   3 /*-
   4  * Copyright (c)2001 Citrus Project,
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  *
  28  * $Citrus$
  29  */
  30
  31 #include <sys/cdefs.h>
  32 #if defined(LIBC_SCCS) && !defined(lint)
  33 __RCSID("$NetBSD$");
  34 #endif /* LIBC_SCCS and not lint */
  35
  36 #include <assert.h>
  37 #include <errno.h>
  38 #include <stdio.h>
  39 #include <wchar.h>
  40 #include "reentrant.h"
  41 #include "local.h"
  42
  43 wint_t
  44 ungetwc(wint_t wc, FILE *fp)
  45 {
  46         struct wchar_io_data *wcio;
  47
  48         _DIAGASSERT(fp);
  49
  50         if (wc == WEOF)
  51                 return WEOF;
  52
  53         FLOCKFILE(fp);
  54         _SET_ORIENTATION(fp, 1);
  55         /*
  56          * XXX since we have no way to transform a wchar string to
  57          * a char string in reverse order, we can't use ungetc.
  58          */
  59         /* XXX should we flush ungetc buffer? */
  60
  61         wcio = WCIO_GET(fp);
  62         if (wcio == 0) {
  63                 FUNLOCKFILE(fp);
  64                 errno = ENOMEM; /* XXX */
  65                 return WEOF;
  66         }
  67
  68         if (wcio->wcio_ungetwc_inbuf >= WCIO_UNGETWC_BUFSIZE) {
  69                 FUNLOCKFILE(fp);
  70                 return WEOF;
  71         }
  72
  73         wcio->wcio_ungetwc_buf[wcio->wcio_ungetwc_inbuf++] = wc;
  74         __sclearerr(fp);
  75         FUNLOCKFILE(fp);
  76
  77         return wc;
  78 }