1 /* $NetBSD: telldir.c,v 1.19 2008/05/04 18:53:26 tonnerre Exp $ */ 2 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 <sys/cdefs.h> 33 #if defined(LIBC_SCCS) && !defined(lint) 34 #if 0 35 static char sccsid[] = "@(#)telldir.c 8.1 (Berkeley) 6/4/93"; 36 #else 37 __RCSID("$NetBSD: telldir.c,v 1.19 2008/05/04 18:53:26 tonnerre Exp $"); 38 #endif 39 #endif /* LIBC_SCCS and not lint */ 40 41 #include "namespace.h" 42 #include "reentrant.h" 43 #include "extern.h" 44 #include <sys/param.h> 45 46 #include <assert.h> 47 #include <dirent.h> 48 #include <stdlib.h> 49 #include <unistd.h> 50 51 #include "dirent_private.h" 52 53 #ifdef __weak_alias 54 __weak_alias(telldir,_telldir) 55 #endif 56 57 long 58 telldir(DIR *dirp) 59 { 60 long rv; 61 #ifdef _REENTRANT 62 if (__isthreaded) { 63 mutex_lock((mutex_t *)dirp->dd_lock); 64 rv = (intptr_t)_telldir_unlocked(dirp); 65 mutex_unlock((mutex_t *)dirp->dd_lock); 66 } else 67 #endif 68 rv = (intptr_t)_telldir_unlocked(dirp); 69 return rv; 70 } 71 72 /* 73 * return a pointer into a directory 74 */ 75 long 76 _telldir_unlocked(DIR *dirp) 77 { 78 struct dirpos *lp; 79 80 for (lp = dirp->dd_internal; lp; lp = lp->dp_next) 81 if (lp->dp_seek == dirp->dd_seek && 82 lp->dp_loc == dirp->dd_loc) 83 return (intptr_t)lp; 84 85 if ((lp = malloc(sizeof(*lp))) == NULL) 86 return (-1); 87 88 lp->dp_seek = dirp->dd_seek; 89 lp->dp_loc = dirp->dd_loc; 90 lp->dp_next = dirp->dd_internal; 91 dirp->dd_internal = lp; 92 93 return (intptr_t)lp; 94 } 95 96 /* 97 * seek to an entry in a directory. 98 * Only values returned by "telldir" should be passed to seekdir. 99 */ 100 void 101 _seekdir_unlocked(DIR *dirp, long loc) 102 { 103 struct dirpos *lp; 104 105 _DIAGASSERT(dirp != NULL); 106 107 for (lp = dirp->dd_internal; lp; lp = lp->dp_next) 108 if ((intptr_t)lp == loc) 109 break; 110 111 if (lp == NULL) 112 return; 113 114 if (lp->dp_loc == dirp->dd_loc && lp->dp_seek == dirp->dd_seek) 115 return; 116 117 dirp->dd_seek = lseek(dirp->dd_fd, lp->dp_seek, SEEK_SET); 118 dirp->dd_loc = 0; 119 while (dirp->dd_loc < lp->dp_loc) 120 if (_readdir_unlocked(dirp, 0) == NULL) 121 break; 122 } 123