ungetwc.c revision 1.4 
1/*	$OpenBSD: ungetwc.c,v 1.4 2009/11/09 00:18:27 kurt Exp $	*/
2/* $NetBSD: ungetwc.c,v 1.2 2003/01/18 11:29:59 thorpej Exp $ */
3
4/*-
5 * Copyright (c)2001 Citrus Project,
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 *
29 * $Citrus$
30 */
31
32#include <errno.h>
33#include <stdio.h>
34#include <wchar.h>
35#include "local.h"
36
37wint_t
38ungetwc(wint_t wc, FILE *fp)
39{
40	struct wchar_io_data *wcio;
41
42	if (wc == WEOF)
43		return WEOF;
44
45	FLOCKFILE(fp);
46	_SET_ORIENTATION(fp, 1);
47	/*
48	 * XXX since we have no way to transform a wchar string to
49	 * a char string in reverse order, we can't use ungetc.
50	 */
51	/* XXX should we flush ungetc buffer? */
52
53	wcio = WCIO_GET(fp);
54	if (wcio == 0) {
55		FUNLOCKFILE(fp);
56		errno = ENOMEM; /* XXX */
57		return WEOF;
58	}
59
60	if (wcio->wcio_ungetwc_inbuf >= WCIO_UNGETWC_BUFSIZE) {
61		FUNLOCKFILE(fp);
62		return WEOF;
63	}
64
65	wcio->wcio_ungetwc_buf[wcio->wcio_ungetwc_inbuf++] = wc;
66	__sclearerr(fp);
67	FUNLOCKFILE(fp);
68
69	return wc;
70}
71