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
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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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25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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32 #include "namespace.h"
33 #include <sys/param.h>
34 #include <sys/queue.h>
39 #include "un-namespace.h"
41 #include "libc_private.h"
42 #include "gen-private.h"
46 * return a pointer into a directory
51 struct ddloc_mem *lp, *flp;
52 union ddloc_packed ddloc;
55 _pthread_mutex_lock(&dirp->dd_lock);
58 * 1) If the directory position fits in a packed structure, return that.
59 * 2) Otherwise, see if it's already been recorded in the linked list
60 * 3) Otherwise, malloc a new one
62 if (dirp->dd_seek < (off_t)(1l << DD_SEEK_BITS) &&
63 dirp->dd_loc < (1l << DD_LOC_BITS)) {
64 ddloc.s.is_packed = 1;
65 ddloc.s.loc = dirp->dd_loc;
66 ddloc.s.seek = dirp->dd_seek;
71 LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
72 if (lp->loc_seek == dirp->dd_seek) {
75 if (lp->loc_loc == dirp->dd_loc)
77 } else if (flp != NULL) {
83 lp = malloc(sizeof(struct ddloc_mem));
86 _pthread_mutex_unlock(&dirp->dd_lock);
89 lp->loc_index = dirp->dd_td->td_loccnt++;
90 lp->loc_seek = dirp->dd_seek;
91 lp->loc_loc = dirp->dd_loc;
93 LIST_INSERT_BEFORE(flp, lp, loc_lqe);
95 LIST_INSERT_HEAD(&dirp->dd_td->td_locq, lp, loc_lqe);
97 ddloc.i.is_packed = 0;
99 * Technically this assignment could overflow on 32-bit architectures,
100 * but we would get ENOMEM long before that happens.
102 ddloc.i.index = lp->loc_index;
106 _pthread_mutex_unlock(&dirp->dd_lock);
111 * seek to an entry in a directory.
112 * Only values returned by "telldir" should be passed to seekdir.
115 _seekdir(DIR *dirp, long loc)
117 struct ddloc_mem *lp;
119 union ddloc_packed ddloc;
125 if (ddloc.s.is_packed) {
126 loc_seek = ddloc.s.seek;
127 loc_loc = ddloc.s.loc;
129 LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
130 if (lp->loc_index == ddloc.i.index)
136 loc_seek = lp->loc_seek;
137 loc_loc = lp->loc_loc;
139 if (loc_loc == dirp->dd_loc && loc_seek == dirp->dd_seek)
142 /* If it's within the same chunk of data, don't bother reloading. */
143 if (loc_seek == dirp->dd_seek) {
145 * If we go back to 0 don't make the next readdir
146 * trigger a call to getdirentries().
149 dirp->dd_flags |= __DTF_SKIPREAD;
150 dirp->dd_loc = loc_loc;
153 (void) lseek(dirp->dd_fd, (off_t)loc_seek, SEEK_SET);
154 dirp->dd_seek = loc_seek;
156 dirp->dd_flags &= ~__DTF_SKIPREAD; /* current contents are invalid */
157 while (dirp->dd_loc < loc_loc) {
158 dp = _readdir_unlocked(dirp, 0);
165 * After readdir returns the last entry in a block, a call to telldir
166 * returns a location that is after the end of that last entry.
167 * However, that location doesn't refer to a valid directory entry.
168 * Ideally, the call to telldir would return a location that refers to
169 * the first entry in the next block. That location is not known
170 * until the next block is read, so readdir calls this function after
171 * fetching a new block to fix any such telldir locations.
174 _fixtelldir(DIR *dirp, long oldseek, long oldloc)
176 struct ddloc_mem *lp;
178 lp = LIST_FIRST(&dirp->dd_td->td_locq);
180 if (lp->loc_loc == oldloc &&
181 lp->loc_seek == oldseek) {
182 lp->loc_seek = dirp->dd_seek;
183 lp->loc_loc = dirp->dd_loc;
189 * Reclaim memory for telldir cookies which weren't used.
192 _reclaim_telldir(DIR *dirp)
194 struct ddloc_mem *lp;
195 struct ddloc_mem *templp;
197 lp = LIST_FIRST(&dirp->dd_td->td_locq);
200 lp = LIST_NEXT(lp, loc_lqe);
203 LIST_INIT(&dirp->dd_td->td_locq);