xref: /illumos-gate/usr/src/lib/libc/port/stdio/fseek.c (revision 71269a2275bf5a143dad6461eee2710a344e7261)
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 #pragma ident	"%Z%%M%	%I%	%E% SMI"
31 
32 /*
33  * Seek for standard library.  Coordinates with buffering.
34  */
35 
36 #pragma weak _fseek = fseek
37 
38 #include "lint.h"
39 #include "file64.h"
40 #include "mtlib.h"
41 #include <stdio.h>
42 #include <errno.h>
43 #include <thread.h>
44 #include <synch.h>
45 #include <unistd.h>
46 #include <sys/types.h>
47 #include "stdiom.h"
48 
49 int
50 fseek(FILE *iop, long offset, int ptrname)
51 {
52 	off_t	p;
53 	rmutex_t *lk;
54 
55 	FLOCKFILE(lk, iop);
56 	iop->_flag &= ~_IOEOF;
57 
58 	if (!(iop->_flag & _IOREAD) && !(iop->_flag & (_IOWRT | _IORW))) {
59 		errno = EBADF;
60 		FUNLOCKFILE(lk);
61 		return (-1);
62 	}
63 
64 	if (iop->_flag & _IOREAD) {
65 		if (ptrname == 1 && iop->_base && !(iop->_flag&_IONBF)) {
66 			offset -= iop->_cnt;
67 		}
68 	} else if (iop->_flag & (_IOWRT | _IORW)) {
69 		if (_fflush_u(iop) == EOF) {
70 			FUNLOCKFILE(lk);
71 			return (-1);
72 		}
73 	}
74 	iop->_cnt = 0;
75 	iop->_ptr = iop->_base;
76 	if (iop->_flag & _IORW) {
77 		iop->_flag &= ~(_IOREAD | _IOWRT);
78 	}
79 	p = lseek(FILENO(iop), (off_t)offset, ptrname);
80 	FUNLOCKFILE(lk);
81 	return ((p == (off_t)-1) ? -1: 0);
82 }
83