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