1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 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 #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("$FreeBSD$"); 37 38 #include "namespace.h" 39 #include <sys/param.h> 40 #include <sys/queue.h> 41 #include <dirent.h> 42 #include <pthread.h> 43 #include <stdlib.h> 44 #include <unistd.h> 45 #include "un-namespace.h" 46 47 #include "libc_private.h" 48 #include "gen-private.h" 49 #include "telldir.h" 50 51 /* 52 * return a pointer into a directory 53 */ 54 long 55 telldir(DIR *dirp) 56 { 57 struct ddloc *lp, *flp; 58 long idx; 59 60 if (__isthreaded) 61 _pthread_mutex_lock(&dirp->dd_lock); 62 flp = NULL; 63 LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) { 64 if (lp->loc_seek == dirp->dd_seek) { 65 if (flp == NULL) 66 flp = lp; 67 if (lp->loc_loc == dirp->dd_loc) 68 break; 69 } else if (flp != NULL) { 70 lp = NULL; 71 break; 72 } 73 } 74 if (lp == NULL) { 75 lp = malloc(sizeof(struct ddloc)); 76 if (lp == NULL) { 77 if (__isthreaded) 78 _pthread_mutex_unlock(&dirp->dd_lock); 79 return (-1); 80 } 81 lp->loc_index = dirp->dd_td->td_loccnt++; 82 lp->loc_seek = dirp->dd_seek; 83 lp->loc_loc = dirp->dd_loc; 84 if (flp != NULL) 85 LIST_INSERT_BEFORE(flp, lp, loc_lqe); 86 else 87 LIST_INSERT_HEAD(&dirp->dd_td->td_locq, lp, loc_lqe); 88 } 89 idx = lp->loc_index; 90 if (__isthreaded) 91 _pthread_mutex_unlock(&dirp->dd_lock); 92 return (idx); 93 } 94 95 /* 96 * seek to an entry in a directory. 97 * Only values returned by "telldir" should be passed to seekdir. 98 */ 99 void 100 _seekdir(DIR *dirp, long loc) 101 { 102 struct ddloc *lp; 103 struct dirent *dp; 104 105 LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) { 106 if (lp->loc_index == loc) 107 break; 108 } 109 if (lp == NULL) 110 return; 111 if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek) 112 return; 113 114 /* If it's within the same chunk of data, don't bother reloading. */ 115 if (lp->loc_seek == dirp->dd_seek) { 116 /* 117 * If we go back to 0 don't make the next readdir 118 * trigger a call to getdirentries(). 119 */ 120 if (lp->loc_loc == 0) 121 dirp->dd_flags |= __DTF_SKIPREAD; 122 dirp->dd_loc = lp->loc_loc; 123 return; 124 } 125 (void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET); 126 dirp->dd_seek = lp->loc_seek; 127 dirp->dd_loc = 0; 128 dirp->dd_flags &= ~__DTF_SKIPREAD; /* current contents are invalid */ 129 while (dirp->dd_loc < lp->loc_loc) { 130 dp = _readdir_unlocked(dirp, 0); 131 if (dp == NULL) 132 break; 133 } 134 } 135 136 /* 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. 144 */ 145 void 146 _fixtelldir(DIR *dirp, long oldseek, long oldloc) 147 { 148 struct ddloc *lp; 149 150 lp = LIST_FIRST(&dirp->dd_td->td_locq); 151 if (lp != NULL) { 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; 156 } 157 } 158 } 159 160 /* 161 * Reclaim memory for telldir cookies which weren't used. 162 */ 163 void 164 _reclaim_telldir(DIR *dirp) 165 { 166 struct ddloc *lp; 167 struct ddloc *templp; 168 169 lp = LIST_FIRST(&dirp->dd_td->td_locq); 170 while (lp != NULL) { 171 templp = lp; 172 lp = LIST_NEXT(lp, loc_lqe); 173 free(templp); 174 } 175 LIST_INIT(&dirp->dd_td->td_locq); 176 } 177