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 #include "lint.h"
31 #include "file64.h"
32 #include "mtlib.h"
33 #include <sys/types.h>
34 #include <stdio.h>
35 #include <thread.h>
36 #include <synch.h>
37 #include "stdiom.h"
38
39 int _ungetc_unlocked(int c, FILE *iop);
40
41 int
ungetc(int c,FILE * iop)42 ungetc(int c, FILE *iop)
43 {
44 FLOCKRETURN(iop, _ungetc_unlocked(c, iop))
45 }
46
47 /*
48 * Called internally by the library (instead of the safe "ungetc") when
49 * iop->_lock is already held at a higher level - required since we do not
50 * have recursive locks.
51 */
52 int
_ungetc_unlocked(int c,FILE * iop)53 _ungetc_unlocked(int c, FILE *iop)
54 {
55 if (c == EOF)
56 return (EOF);
57 if (iop->_ptr <= iop->_base) {
58 if (iop->_base == 0) {
59 if (_findbuf(iop) == 0)
60 return (EOF);
61 } else if (iop->_ptr <= iop->_base - PUSHBACK)
62 return (EOF);
63 }
64 if ((iop->_flag & _IOREAD) == 0) /* basically a no-op on write stream */
65 ++iop->_ptr;
66 if (*--iop->_ptr != (unsigned char) c)
67 *iop->_ptr = (unsigned char) c; /* was *--iop->_ptr = c; */
68 ++iop->_cnt;
69 iop->_flag &= ~_IOEOF;
70 return (c);
71 }
72