xref: /illumos-gate/usr/src/lib/libc/port/stdio/_wrtchk.c (revision ddb365bfc9e868ad24ccdcb0dc91af18b10df082)
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 <stdio.h>
33 #include <errno.h>
34 #include <sys/types.h>
35 #include "stdiom.h"
36 
37 #undef _wrtchk
38 
39 /* check permissions, correct for read & write changes */
40 int
41 _wrtchk(FILE *iop)
42 {
43 	if ((iop->_flag & (_IOWRT | _IOEOF)) != _IOWRT) {
44 		if (!(iop->_flag & (_IOWRT | _IORW))) {
45 			iop->_flag |= _IOERR;
46 			errno = EBADF;
47 			return (EOF); /* stream is not writeable */
48 		}
49 		iop->_flag = (iop->_flag & ~_IOEOF) | _IOWRT;
50 	}
51 
52 	/* if first I/O to the stream get a buffer */
53 	if (iop->_base == NULL && _findbuf(iop) == NULL)
54 		return (EOF);
55 	else if ((iop->_ptr == iop->_base) &&
56 	    !(iop->_flag & (_IOLBF | _IONBF))) {
57 		iop->_cnt = _bufend(iop) - iop->_ptr;
58 	}
59 	return (0);
60 }
61