xref: /titanic_41/usr/src/lib/libc/port/stdio/fseek.c (revision fd9cb95cbb2f626355a60efb9d02c5f0a33c10e6)
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 /*
34  * Seek for standard library.  Coordinates with buffering.
35  */
36 
37 #pragma weak fseek = _fseek
38 
39 #include "synonyms.h"
40 #include "file64.h"
41 #include "mtlib.h"
42 #include <stdio.h>
43 #include <errno.h>
44 #include <thread.h>
45 #include <synch.h>
46 #include <unistd.h>
47 #include <sys/types.h>
48 #include "stdiom.h"
49 
50 int
51 fseek(FILE *iop, long offset, int ptrname)
52 {
53 	off_t	p;
54 	rmutex_t *lk;
55 
56 	FLOCKFILE(lk, iop);
57 	iop->_flag &= ~_IOEOF;
58 
59 	if (!(iop->_flag & _IOREAD) && !(iop->_flag & (_IOWRT | _IORW))) {
60 		errno = EBADF;
61 		FUNLOCKFILE(lk);
62 		return (-1);
63 	}
64 
65 	if (iop->_flag & _IOREAD) {
66 		if (ptrname == 1 && iop->_base && !(iop->_flag&_IONBF)) {
67 			offset -= iop->_cnt;
68 		}
69 	} else if (iop->_flag & (_IOWRT | _IORW)) {
70 		if (_fflush_u(iop) == EOF) {
71 			FUNLOCKFILE(lk);
72 			return (-1);
73 		}
74 	}
75 	iop->_cnt = 0;
76 	iop->_ptr = iop->_base;
77 	if (iop->_flag & _IORW) {
78 		iop->_flag &= ~(_IOREAD | _IOWRT);
79 	}
80 	p = lseek(FILENO(iop), (off_t)offset, ptrname);
81 	FUNLOCKFILE(lk);
82 	return ((p == (off_t)-1) ? -1: 0);
83 }
84