1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22/*
23 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27/*	Copyright (c) 1988 AT&T	*/
28/*	  All Rights Reserved  	*/
29
30#pragma ident	"%Z%%M%	%I%	%E% SMI"
31
32#include "lint.h"
33#include "file64.h"
34#include "mtlib.h"
35#include <sys/types.h>
36#include <stdio.h>
37#include <thread.h>
38#include <synch.h>
39#include "stdiom.h"
40
41int _ungetc_unlocked(int c, FILE *iop);
42
43int
44ungetc(int c, FILE *iop)
45{
46	FLOCKRETURN(iop, _ungetc_unlocked(c, iop))
47}
48
49/*
50 * Called internally by the library (instead of the safe "ungetc") when
51 * iop->_lock is already held at a higher level - required since we do not
52 * have recursive locks.
53 */
54int
55_ungetc_unlocked(int c, FILE *iop)
56{
57	if (c == EOF)
58		return (EOF);
59	if (iop->_ptr <= iop->_base) {
60		if (iop->_base == 0) {
61			if (_findbuf(iop) == 0)
62				return (EOF);
63		} else if (iop->_ptr <= iop->_base - PUSHBACK)
64			return (EOF);
65	}
66	if ((iop->_flag & _IOREAD) == 0) /* basically a no-op on write stream */
67		++iop->_ptr;
68	if (*--iop->_ptr != (unsigned char) c)
69		*iop->_ptr = (unsigned char) c;  /* was *--iop->_ptr = c; */
70	++iop->_cnt;
71	iop->_flag &= ~_IOEOF;
72	return (c);
73}
74