2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1983, 1993
5 * The Regents of the University of California. All rights reserved.
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8 * modification, are permitted provided that the following conditions
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.
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
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24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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32 #if defined(LIBC_SCCS) && !defined(lint)
33 static char sccsid[] = "@(#)telldir.c 8.1 (Berkeley) 6/4/93";
34 #endif /* LIBC_SCCS and not lint */
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
38 #include "namespace.h"
39 #include <sys/param.h>
40 #include <sys/queue.h>
45 #include "un-namespace.h"
47 #include "libc_private.h"
48 #include "gen-private.h"
52 * return a pointer into a directory
57 struct ddloc *lp, *flp;
61 _pthread_mutex_lock(&dirp->dd_lock);
63 LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
64 if (lp->loc_seek == dirp->dd_seek) {
67 if (lp->loc_loc == dirp->dd_loc)
69 } else if (flp != NULL) {
75 lp = malloc(sizeof(struct ddloc));
78 _pthread_mutex_unlock(&dirp->dd_lock);
81 lp->loc_index = dirp->dd_td->td_loccnt++;
82 lp->loc_seek = dirp->dd_seek;
83 lp->loc_loc = dirp->dd_loc;
85 LIST_INSERT_BEFORE(flp, lp, loc_lqe);
87 LIST_INSERT_HEAD(&dirp->dd_td->td_locq, lp, loc_lqe);
91 _pthread_mutex_unlock(&dirp->dd_lock);
96 * seek to an entry in a directory.
97 * Only values returned by "telldir" should be passed to seekdir.
100 _seekdir(DIR *dirp, long loc)
105 LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
106 if (lp->loc_index == loc)
111 if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek)
114 /* If it's within the same chunk of data, don't bother reloading. */
115 if (lp->loc_seek == dirp->dd_seek) {
117 * If we go back to 0 don't make the next readdir
118 * trigger a call to getdirentries().
120 if (lp->loc_loc == 0)
121 dirp->dd_flags |= __DTF_SKIPREAD;
122 dirp->dd_loc = lp->loc_loc;
125 (void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET);
126 dirp->dd_seek = lp->loc_seek;
128 dirp->dd_flags &= ~__DTF_SKIPREAD; /* current contents are invalid */
129 while (dirp->dd_loc < lp->loc_loc) {
130 dp = _readdir_unlocked(dirp, 0);
137 * After readdir returns the last entry in a block, a call to telldir
138 * returns a location that is after the end of that last entry.
139 * However, that location doesn't refer to a valid directory entry.
140 * Ideally, the call to telldir would return a location that refers to
141 * the first entry in the next block. That location is not known
142 * until the next block is read, so readdir calls this function after
143 * fetching a new block to fix any such telldir locations.
146 _fixtelldir(DIR *dirp, long oldseek, long oldloc)
150 lp = LIST_FIRST(&dirp->dd_td->td_locq);
152 if (lp->loc_loc == oldloc &&
153 lp->loc_seek == oldseek) {
154 lp->loc_seek = dirp->dd_seek;
155 lp->loc_loc = dirp->dd_loc;
161 * Reclaim memory for telldir cookies which weren't used.
164 _reclaim_telldir(DIR *dirp)
167 struct ddloc *templp;
169 lp = LIST_FIRST(&dirp->dd_td->td_locq);
172 lp = LIST_NEXT(lp, loc_lqe);
175 LIST_INIT(&dirp->dd_td->td_locq);