xref: /illumos-gate/usr/src/lib/libc/port/stdio/_wrtchk.c (revision c69906bdd99a073749de104d2fa9cd6bf889f3c5)
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 */
43 int
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