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