telldir.c revision 270002 
1/*
2 * Copyright (c) 1983, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#if defined(LIBC_SCCS) && !defined(lint)
31static char sccsid[] = "@(#)telldir.c	8.1 (Berkeley) 6/4/93";
32#endif /* LIBC_SCCS and not lint */
33#include <sys/cdefs.h>
34__FBSDID("$FreeBSD: stable/10/lib/libc/gen/telldir.c 270002 2014-08-14 20:20:21Z jhb $");
35
36#include "namespace.h"
37#include <sys/param.h>
38#include <sys/queue.h>
39#include <dirent.h>
40#include <pthread.h>
41#include <stdlib.h>
42#include <unistd.h>
43#include "un-namespace.h"
44
45#include "libc_private.h"
46#include "gen-private.h"
47#include "telldir.h"
48
49/*
50 * return a pointer into a directory
51 */
52long
53telldir(dirp)
54	DIR *dirp;
55{
56	struct ddloc *lp;
57	long idx;
58
59	if (__isthreaded)
60		_pthread_mutex_lock(&dirp->dd_lock);
61	LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
62		if (lp->loc_seek == dirp->dd_seek &&
63		    lp->loc_loc == dirp->dd_loc)
64			break;
65	}
66	if (lp == NULL) {
67		lp = malloc(sizeof(struct ddloc));
68		if (lp == NULL) {
69			if (__isthreaded)
70				_pthread_mutex_unlock(&dirp->dd_lock);
71			return (-1);
72		}
73		lp->loc_index = dirp->dd_td->td_loccnt++;
74		lp->loc_seek = dirp->dd_seek;
75		lp->loc_loc = dirp->dd_loc;
76		LIST_INSERT_HEAD(&dirp->dd_td->td_locq, lp, loc_lqe);
77	}
78	idx = lp->loc_index;
79	if (__isthreaded)
80		_pthread_mutex_unlock(&dirp->dd_lock);
81	return (idx);
82}
83
84/*
85 * seek to an entry in a directory.
86 * Only values returned by "telldir" should be passed to seekdir.
87 */
88void
89_seekdir(dirp, loc)
90	DIR *dirp;
91	long loc;
92{
93	struct ddloc *lp;
94	struct dirent *dp;
95
96	LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
97		if (lp->loc_index == loc)
98			break;
99	}
100	if (lp == NULL)
101		return;
102	if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek)
103		return;
104	(void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET);
105	dirp->dd_seek = lp->loc_seek;
106	dirp->dd_loc = 0;
107	while (dirp->dd_loc < lp->loc_loc) {
108		dp = _readdir_unlocked(dirp, 0);
109		if (dp == NULL)
110			break;
111	}
112}
113
114/*
115 * Reclaim memory for telldir cookies which weren't used.
116 */
117void
118_reclaim_telldir(dirp)
119	DIR *dirp;
120{
121	struct ddloc *lp;
122	struct ddloc *templp;
123
124	lp = LIST_FIRST(&dirp->dd_td->td_locq);
125	while (lp != NULL) {
126		templp = lp;
127		lp = LIST_NEXT(lp, loc_lqe);
128		free(templp);
129	}
130	LIST_INIT(&dirp->dd_td->td_locq);
131}
132