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 * 3. 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) 31 static char sccsid[] = "@(#)telldir.c 8.1 (Berkeley) 6/4/93"; 32 #endif /* LIBC_SCCS and not lint */ 33 #include <sys/cdefs.h> 34 __FBSDID("$FreeBSD$"); 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 */ 52 long 53 telldir(DIR *dirp) 54 { 55 struct ddloc *lp, *flp; 56 long idx; 57 58 if (__isthreaded) 59 _pthread_mutex_lock(&dirp->dd_lock); 60 flp = NULL; 61 LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) { 62 if (lp->loc_seek == dirp->dd_seek) { 63 if (flp == NULL) 64 flp = lp; 65 if (lp->loc_loc == dirp->dd_loc) 66 break; 67 } else if (flp != NULL) { 68 lp = NULL; 69 break; 70 } 71 } 72 if (lp == NULL) { 73 lp = malloc(sizeof(struct ddloc)); 74 if (lp == NULL) { 75 if (__isthreaded) 76 _pthread_mutex_unlock(&dirp->dd_lock); 77 return (-1); 78 } 79 lp->loc_index = dirp->dd_td->td_loccnt++; 80 lp->loc_seek = dirp->dd_seek; 81 lp->loc_loc = dirp->dd_loc; 82 if (flp != NULL) 83 LIST_INSERT_BEFORE(flp, lp, loc_lqe); 84 else 85 LIST_INSERT_HEAD(&dirp->dd_td->td_locq, lp, loc_lqe); 86 } 87 idx = lp->loc_index; 88 if (__isthreaded) 89 _pthread_mutex_unlock(&dirp->dd_lock); 90 return (idx); 91 } 92 93 /* 94 * seek to an entry in a directory. 95 * Only values returned by "telldir" should be passed to seekdir. 96 */ 97 void 98 _seekdir(DIR *dirp, long loc) 99 { 100 struct ddloc *lp; 101 struct dirent *dp; 102 103 LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) { 104 if (lp->loc_index == loc) 105 break; 106 } 107 if (lp == NULL) 108 return; 109 if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek) 110 return; 111 112 /* If it's within the same chunk of data, don't bother reloading. */ 113 if (lp->loc_seek == dirp->dd_seek) { 114 /* 115 * If we go back to 0 don't make the next readdir 116 * trigger a call to getdirentries(). 117 */ 118 if (lp->loc_loc == 0) 119 dirp->dd_flags |= __DTF_SKIPREAD; 120 dirp->dd_loc = lp->loc_loc; 121 return; 122 } 123 (void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET); 124 dirp->dd_seek = lp->loc_seek; 125 dirp->dd_loc = 0; 126 dirp->dd_flags &= ~__DTF_SKIPREAD; /* current contents are invalid */ 127 while (dirp->dd_loc < lp->loc_loc) { 128 dp = _readdir_unlocked(dirp, 0); 129 if (dp == NULL) 130 break; 131 } 132 } 133 134 /* 135 * After readdir returns the last entry in a block, a call to telldir 136 * returns a location that is after the end of that last entry. 137 * However, that location doesn't refer to a valid directory entry. 138 * Ideally, the call to telldir would return a location that refers to 139 * the first entry in the next block. That location is not known 140 * until the next block is read, so readdir calls this function after 141 * fetching a new block to fix any such telldir locations. 142 */ 143 void 144 _fixtelldir(DIR *dirp, long oldseek, long oldloc) 145 { 146 struct ddloc *lp; 147 148 lp = LIST_FIRST(&dirp->dd_td->td_locq); 149 if (lp != NULL) { 150 if (lp->loc_loc == oldloc && 151 lp->loc_seek == oldseek) { 152 lp->loc_seek = dirp->dd_seek; 153 lp->loc_loc = dirp->dd_loc; 154 } 155 } 156 } 157 158 /* 159 * Reclaim memory for telldir cookies which weren't used. 160 */ 161 void 162 _reclaim_telldir(DIR *dirp) 163 { 164 struct ddloc *lp; 165 struct ddloc *templp; 166 167 lp = LIST_FIRST(&dirp->dd_td->td_locq); 168 while (lp != NULL) { 169 templp = lp; 170 lp = LIST_NEXT(lp, loc_lqe); 171 free(templp); 172 } 173 LIST_INIT(&dirp->dd_td->td_locq); 174 } 175