1 /* $OpenBSD: telldir.c,v 1.13 2008/05/01 19:49:18 otto Exp $ */ 2 /* 3 * Copyright (c) 1983, 1993 4 * The Regents of the University of California. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of the University nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 */ 30 31 #include <sys/param.h> 32 #include <sys/queue.h> 33 #include <dirent.h> 34 #include <stdlib.h> 35 #include <unistd.h> 36 37 #include "thread_private.h" 38 #include "telldir.h" 39 40 int _readdir_unlocked(DIR *, struct dirent **, int); 41 42 /* 43 * return a pointer into a directory 44 */ 45 long 46 _telldir_unlocked(DIR *dirp) 47 { 48 long i; 49 struct ddloc *lp; 50 51 i = dirp->dd_td->td_last; 52 lp = &dirp->dd_td->td_locs[i]; 53 54 /* return previous telldir, if there */ 55 for (; i < dirp->dd_td->td_loccnt; i++, lp++) { 56 if (lp->loc_seek == dirp->dd_seek && 57 lp->loc_loc == dirp->dd_loc) { 58 dirp->dd_td->td_last = i; 59 return (i); 60 } 61 } 62 63 if (dirp->dd_td->td_loccnt == dirp->dd_td->td_sz) { 64 size_t newsz = dirp->dd_td->td_sz * 2 + 1; 65 struct ddloc *p; 66 p = realloc(dirp->dd_td->td_locs, newsz * sizeof(*p)); 67 if (p == NULL) 68 return (-1); 69 dirp->dd_td->td_sz = newsz; 70 dirp->dd_td->td_locs = p; 71 lp = &dirp->dd_td->td_locs[i]; 72 } 73 dirp->dd_td->td_loccnt++; 74 lp->loc_seek = dirp->dd_seek; 75 lp->loc_loc = dirp->dd_loc; 76 dirp->dd_td->td_last = i; 77 return (i); 78 } 79 80 long 81 telldir(DIR *dirp) 82 { 83 long i; 84 85 _MUTEX_LOCK(&dirp->dd_lock); 86 i = _telldir_unlocked(dirp); 87 _MUTEX_UNLOCK(&dirp->dd_lock); 88 89 return (i); 90 } 91 92 /* 93 * seek to an entry in a directory. 94 * Only values returned by "telldir" should be passed to seekdir. 95 */ 96 void 97 __seekdir(DIR *dirp, long loc) 98 { 99 struct ddloc *lp; 100 struct dirent *dp; 101 102 if (loc < 0 || loc >= dirp->dd_td->td_loccnt) 103 return; 104 lp = &dirp->dd_td->td_locs[loc]; 105 dirp->dd_td->td_last = loc; 106 if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek) 107 return; 108 (void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET); 109 dirp->dd_seek = lp->loc_seek; 110 dirp->dd_loc = 0; 111 while (dirp->dd_loc < lp->loc_loc) { 112 _readdir_unlocked(dirp, &dp, 0); 113 if (dp == NULL) 114 break; 115 } 116 } 117