_wrtchk.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
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, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*
23 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27#pragma ident	"%Z%%M%	%I%	%E% SMI"
28
29/*	Copyright (c) 1988 AT&T	*/
30/*	  All Rights Reserved  	*/
31
32
33#include "synonyms.h"
34#include "file64.h"
35#include <stdio.h>
36#include <errno.h>
37#include <sys/types.h>
38#include "stdiom.h"
39
40#undef _wrtchk
41
42/* check permissions, correct for read & write changes */
43int
44_wrtchk(FILE *iop)
45{
46	if ((iop->_flag & (_IOWRT | _IOEOF)) != _IOWRT) {
47		if (!(iop->_flag & (_IOWRT | _IORW))) {
48			iop->_flag |= _IOERR;
49			errno = EBADF;
50			return (EOF); /* stream is not writeable */
51		}
52		iop->_flag = (iop->_flag & ~_IOEOF) | _IOWRT;
53	}
54
55	/* if first I/O to the stream get a buffer */
56	if (iop->_base == NULL && _findbuf(iop) == NULL)
57		return (EOF);
58	else if ((iop->_ptr == iop->_base) &&
59	    !(iop->_flag & (_IOLBF | _IONBF))) {
60		iop->_cnt = _bufend(iop) - iop->_ptr;
61	}
62	return (0);
63}
64