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 #include "namespace.h" 33 #include <sys/param.h> 34 #include <sys/queue.h> 35 #include <dirent.h> 36 #include <pthread.h> 37 #include <stdlib.h> 38 #include <unistd.h> 39 #include "un-namespace.h" 40 41 #include "libc_private.h" 42 #include "gen-private.h" 43 #include "telldir.h" 44 45 /* 46 * return a pointer into a directory 47 */ 48 long 49 telldir(DIR *dirp) 50 { 51 struct ddloc_mem *lp, *flp; 52 union ddloc_packed ddloc; 53 54 if (__isthreaded) 55 _pthread_mutex_lock(&dirp->dd_lock); 56 /* 57 * Outline: 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 61 */ 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; 67 goto out; 68 } 69 70 flp = NULL; 71 LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) { 72 if (lp->loc_seek == dirp->dd_seek) { 73 if (flp == NULL) 74 flp = lp; 75 if (lp->loc_loc == dirp->dd_loc) 76 break; 77 } else if (flp != NULL) { 78 lp = NULL; 79 break; 80 } 81 } 82 if (lp == NULL) { 83 lp = malloc(sizeof(struct ddloc_mem)); 84 if (lp == NULL) { 85 if (__isthreaded) 86 _pthread_mutex_unlock(&dirp->dd_lock); 87 return (-1); 88 } 89 lp->loc_index = dirp->dd_td->td_loccnt++; 90 lp->loc_seek = dirp->dd_seek; 91 lp->loc_loc = dirp->dd_loc; 92 if (flp != NULL) 93 LIST_INSERT_BEFORE(flp, lp, loc_lqe); 94 else 95 LIST_INSERT_HEAD(&dirp->dd_td->td_locq, lp, loc_lqe); 96 } 97 ddloc.i.is_packed = 0; 98 /* 99 * Technically this assignment could overflow on 32-bit architectures, 100 * but we would get ENOMEM long before that happens. 101 */ 102 ddloc.i.index = lp->loc_index; 103 104 out: 105 if (__isthreaded) 106 _pthread_mutex_unlock(&dirp->dd_lock); 107 return (ddloc.l); 108 } 109 110 /* 111 * seek to an entry in a directory. 112 * Only values returned by "telldir" should be passed to seekdir. 113 */ 114 void 115 _seekdir(DIR *dirp, long loc) 116 { 117 struct ddloc_mem *lp; 118 struct dirent *dp; 119 union ddloc_packed ddloc; 120 off_t loc_seek; 121 long loc_loc; 122 123 ddloc.l = loc; 124 125 if (ddloc.s.is_packed) { 126 loc_seek = ddloc.s.seek; 127 loc_loc = ddloc.s.loc; 128 } else { 129 LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) { 130 if (lp->loc_index == ddloc.i.index) 131 break; 132 } 133 if (lp == NULL) 134 return; 135 136 loc_seek = lp->loc_seek; 137 loc_loc = lp->loc_loc; 138 } 139 if (loc_loc == dirp->dd_loc && loc_seek == dirp->dd_seek) 140 return; 141 142 /* If it's within the same chunk of data, don't bother reloading. */ 143 if (loc_seek == dirp->dd_seek) { 144 /* 145 * If we go back to 0 don't make the next readdir 146 * trigger a call to getdirentries(). 147 */ 148 if (loc_loc == 0) 149 dirp->dd_flags |= __DTF_SKIPREAD; 150 dirp->dd_loc = loc_loc; 151 return; 152 } 153 (void) lseek(dirp->dd_fd, (off_t)loc_seek, SEEK_SET); 154 dirp->dd_seek = loc_seek; 155 dirp->dd_loc = 0; 156 dirp->dd_flags &= ~__DTF_SKIPREAD; /* current contents are invalid */ 157 while (dirp->dd_loc < loc_loc) { 158 dp = _readdir_unlocked(dirp, 0); 159 if (dp == NULL) 160 break; 161 } 162 } 163 164 /* 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. 172 */ 173 void 174 _fixtelldir(DIR *dirp, long oldseek, long oldloc) 175 { 176 struct ddloc_mem *lp; 177 178 lp = LIST_FIRST(&dirp->dd_td->td_locq); 179 if (lp != NULL) { 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; 184 } 185 } 186 } 187 188 /* 189 * Reclaim memory for telldir cookies which weren't used. 190 */ 191 void 192 _reclaim_telldir(DIR *dirp) 193 { 194 struct ddloc_mem *lp; 195 struct ddloc_mem *templp; 196 197 lp = LIST_FIRST(&dirp->dd_td->td_locq); 198 while (lp != NULL) { 199 templp = lp; 200 lp = LIST_NEXT(lp, loc_lqe); 201 free(templp); 202 } 203 LIST_INIT(&dirp->dd_td->td_locq); 204 } 205