1/*	$NetBSD: telldir.c,v 1.19 2008/05/04 18:53:26 tonnerre Exp $	*/
2
3/*
4 * Copyright (c) 1983, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#include <sys/cdefs.h>
33#if defined(LIBC_SCCS) && !defined(lint)
34#if 0
35static char sccsid[] = "@(#)telldir.c	8.1 (Berkeley) 6/4/93";
36#else
37__RCSID("$NetBSD: telldir.c,v 1.19 2008/05/04 18:53:26 tonnerre Exp $");
38#endif
39#endif /* LIBC_SCCS and not lint */
40
41#include "namespace.h"
42#include "reentrant.h"
43#include "extern.h"
44#include <sys/param.h>
45
46#include <assert.h>
47#include <dirent.h>
48#include <stdlib.h>
49#include <unistd.h>
50
51#include "dirent_private.h"
52
53#ifdef __weak_alias
54__weak_alias(telldir,_telldir)
55#endif
56
57long
58telldir(DIR *dirp)
59{
60	long rv;
61#ifdef _REENTRANT
62	if (__isthreaded) {
63		mutex_lock((mutex_t *)dirp->dd_lock);
64		rv = _telldir_unlocked(dirp);
65		mutex_unlock((mutex_t *)dirp->dd_lock);
66	} else
67#endif
68		rv = _telldir_unlocked(dirp);
69	return rv;
70}
71
72/*
73 * return a pointer into a directory
74 */
75long
76_telldir_unlocked(DIR *dirp)
77{
78	struct dirpos *lp;
79
80	for (lp = dirp->dd_internal; lp; lp = lp->dp_next)
81		if (lp->dp_seek == dirp->dd_seek &&
82		    lp->dp_loc == dirp->dd_loc)
83			return (intptr_t)lp;
84
85	if ((lp = malloc(sizeof(*lp))) == NULL)
86		return (-1);
87
88	lp->dp_seek = dirp->dd_seek;
89	lp->dp_loc = dirp->dd_loc;
90	lp->dp_next = dirp->dd_internal;
91	dirp->dd_internal = lp;
92
93	return (intptr_t)lp;
94}
95
96/*
97 * seek to an entry in a directory.
98 * Only values returned by "telldir" should be passed to seekdir.
99 */
100void
101_seekdir_unlocked(DIR *dirp, long loc)
102{
103	struct dirpos *lp;
104
105	_DIAGASSERT(dirp != NULL);
106
107	for (lp = dirp->dd_internal; lp; lp = lp->dp_next)
108		if ((intptr_t)lp == loc)
109			break;
110
111	if (lp == NULL)
112		return;
113
114	if (lp->dp_loc == dirp->dd_loc && lp->dp_seek == dirp->dd_seek)
115		return;
116
117	dirp->dd_seek = lseek(dirp->dd_fd, lp->dp_seek, SEEK_SET);
118	dirp->dd_loc = 0;
119	while (dirp->dd_loc < lp->dp_loc)
120		if (_readdir_unlocked(dirp, 0) == NULL)
121			break;
122}
123