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>
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34__FBSDID("$FreeBSD: stable/10/lib/libc/gen/telldir.c 270002 2014-08-14 20:20:21Z jhb $");
|
| 34__FBSDID("$FreeBSD: stable/10/lib/libc/gen/telldir.c 282979 2015-05-15 15:49:24Z julian $"); |
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;
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104
105 /* If it's within the same chunk of data, don't bother reloading. */
106 if (lp->loc_seek == dirp->dd_seek) {
107 /*
108 * If we go back to 0 don't make the next readdir
109 * trigger a call to getdirentries().
110 */
111 if (lp->loc_loc == 0)
112 dirp->dd_flags |= __DTF_SKIPREAD;
113 dirp->dd_loc = lp->loc_loc;
114 return;
115 } |
116 (void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET);
117 dirp->dd_seek = lp->loc_seek;
118 dirp->dd_loc = 0;
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| 119 dirp->dd_flags &= ~__DTF_SKIPREAD; /* current contents are invalid */ |
120 while (dirp->dd_loc < lp->loc_loc) {
121 dp = _readdir_unlocked(dirp, 0);
122 if (dp == NULL)
123 break;
124 }
125}
126
127/*
|
128 * After readdir returns the last entry in a block, a call to telldir
129 * returns a location that is after the end of that last entry.
130 * However, that location doesn't refer to a valid directory entry.
131 * Ideally, the call to telldir would return a location that refers to
132 * the first entry in the next block. That location is not known
133 * until the next block is read, so readdir calls this function after
134 * fetching a new block to fix any such telldir locations.
135 */
136void
137_fixtelldir(DIR *dirp, long oldseek, long oldloc)
138{
139 struct ddloc *lp;
140
141 lp = LIST_FIRST(&dirp->dd_td->td_locq);
142 if (lp != NULL) {
143 if (lp->loc_loc == oldloc &&
144 lp->loc_seek == oldseek) {
145 lp->loc_seek = dirp->dd_seek;
146 lp->loc_loc = dirp->dd_loc;
147 }
148 }
149}
150
151/* |
152 * Reclaim memory for telldir cookies which weren't used.
153 */
154void
155_reclaim_telldir(dirp)
156 DIR *dirp;
157{
158 struct ddloc *lp;
159 struct ddloc *templp;
160
161 lp = LIST_FIRST(&dirp->dd_td->td_locq);
162 while (lp != NULL) {
163 templp = lp;
164 lp = LIST_NEXT(lp, loc_lqe);
165 free(templp);
166 }
167 LIST_INIT(&dirp->dd_td->td_locq);
168}
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