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> 34__FBSDID("$FreeBSD: stable/10/lib/libc/gen/telldir.c 317634 2017-05-01 06:03:44Z mav $"); 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, *flp; 57 long idx; 58 59 if (__isthreaded) 60 _pthread_mutex_lock(&dirp->dd_lock); 61 flp = NULL; 62 LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) { 63 if (lp->loc_seek == dirp->dd_seek) { 64 if (flp == NULL) 65 flp = lp; 66 if (lp->loc_loc == dirp->dd_loc) 67 break; 68 } else if (flp != NULL) { 69 lp = NULL; 70 break; 71 } 72 } 73 if (lp == NULL) { 74 lp = malloc(sizeof(struct ddloc)); 75 if (lp == NULL) { 76 if (__isthreaded) 77 _pthread_mutex_unlock(&dirp->dd_lock); 78 return (-1); 79 } 80 lp->loc_index = dirp->dd_td->td_loccnt++; 81 lp->loc_seek = dirp->dd_seek; 82 lp->loc_loc = dirp->dd_loc; 83 if (flp != NULL) 84 LIST_INSERT_BEFORE(flp, lp, loc_lqe); 85 else 86 LIST_INSERT_HEAD(&dirp->dd_td->td_locq, lp, loc_lqe); 87 } 88 idx = lp->loc_index; 89 if (__isthreaded) 90 _pthread_mutex_unlock(&dirp->dd_lock); 91 return (idx); 92} 93 94/* 95 * seek to an entry in a directory. 96 * Only values returned by "telldir" should be passed to seekdir. 97 */ 98void 99_seekdir(dirp, loc) 100 DIR *dirp; 101 long loc; 102{ 103 struct ddloc *lp; 104 struct dirent *dp; 105 106 LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) { 107 if (lp->loc_index == loc) 108 break; 109 } 110 if (lp == NULL) 111 return; 112 if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek) 113 return; 114 115 /* If it's within the same chunk of data, don't bother reloading. */ 116 if (lp->loc_seek == dirp->dd_seek) { 117 /* 118 * If we go back to 0 don't make the next readdir 119 * trigger a call to getdirentries(). 120 */ 121 if (lp->loc_loc == 0) 122 dirp->dd_flags |= __DTF_SKIPREAD; 123 dirp->dd_loc = lp->loc_loc; 124 return; 125 } 126 (void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET); 127 dirp->dd_seek = lp->loc_seek; 128 dirp->dd_loc = 0; 129 dirp->dd_flags &= ~__DTF_SKIPREAD; /* current contents are invalid */ 130 while (dirp->dd_loc < lp->loc_loc) { 131 dp = _readdir_unlocked(dirp, 0); 132 if (dp == NULL) 133 break; 134 } 135} 136 137/* 138 * After readdir returns the last entry in a block, a call to telldir 139 * returns a location that is after the end of that last entry. 140 * However, that location doesn't refer to a valid directory entry. 141 * Ideally, the call to telldir would return a location that refers to 142 * the first entry in the next block. That location is not known 143 * until the next block is read, so readdir calls this function after 144 * fetching a new block to fix any such telldir locations. 145 */ 146void 147_fixtelldir(DIR *dirp, long oldseek, long oldloc) 148{ 149 struct ddloc *lp; 150 151 lp = LIST_FIRST(&dirp->dd_td->td_locq); 152 if (lp != NULL) { 153 if (lp->loc_loc == oldloc && 154 lp->loc_seek == oldseek) { 155 lp->loc_seek = dirp->dd_seek; 156 lp->loc_loc = dirp->dd_loc; 157 } 158 } 159} 160 161/* 162 * Reclaim memory for telldir cookies which weren't used. 163 */ 164void 165_reclaim_telldir(dirp) 166 DIR *dirp; 167{ 168 struct ddloc *lp; 169 struct ddloc *templp; 170 171 lp = LIST_FIRST(&dirp->dd_td->td_locq); 172 while (lp != NULL) { 173 templp = lp; 174 lp = LIST_NEXT(lp, loc_lqe); 175 free(templp); 176 } 177 LIST_INIT(&dirp->dd_td->td_locq); 178} 179