telldir.c revision 1.3.2.2
1 1.3.2.2 jtc /* 2 1.3.2.2 jtc * Copyright (c) 1983, 1993 3 1.3.2.2 jtc * The Regents of the University of California. All rights reserved. 4 1.3.2.2 jtc * 5 1.3.2.2 jtc * Redistribution and use in source and binary forms, with or without 6 1.3.2.2 jtc * modification, are permitted provided that the following conditions 7 1.3.2.2 jtc * are met: 8 1.3.2.2 jtc * 1. Redistributions of source code must retain the above copyright 9 1.3.2.2 jtc * notice, this list of conditions and the following disclaimer. 10 1.3.2.2 jtc * 2. Redistributions in binary form must reproduce the above copyright 11 1.3.2.2 jtc * notice, this list of conditions and the following disclaimer in the 12 1.3.2.2 jtc * documentation and/or other materials provided with the distribution. 13 1.3.2.2 jtc * 3. All advertising materials mentioning features or use of this software 14 1.3.2.2 jtc * must display the following acknowledgement: 15 1.3.2.2 jtc * This product includes software developed by the University of 16 1.3.2.2 jtc * California, Berkeley and its contributors. 17 1.3.2.2 jtc * 4. Neither the name of the University nor the names of its contributors 18 1.3.2.2 jtc * may be used to endorse or promote products derived from this software 19 1.3.2.2 jtc * without specific prior written permission. 20 1.3.2.2 jtc * 21 1.3.2.2 jtc * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 1.3.2.2 jtc * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 1.3.2.2 jtc * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 1.3.2.2 jtc * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 1.3.2.2 jtc * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 1.3.2.2 jtc * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 1.3.2.2 jtc * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 1.3.2.2 jtc * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 1.3.2.2 jtc * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 1.3.2.2 jtc * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 1.3.2.2 jtc * SUCH DAMAGE. 32 1.3.2.2 jtc */ 33 1.3.2.2 jtc 34 1.3.2.2 jtc #if defined(LIBC_SCCS) && !defined(lint) 35 1.3.2.2 jtc /*static char sccsid[] = "from: @(#)telldir.c 8.1 (Berkeley) 6/4/93";*/ 36 1.3.2.2 jtc static char rcsid[] = "$Id: telldir.c,v 1.3.2.2 1994/07/27 14:39:54 jtc Exp $"; 37 1.3.2.2 jtc #endif /* LIBC_SCCS and not lint */ 38 1.3.2.2 jtc 39 1.3.2.2 jtc #include <sys/param.h> 40 1.3.2.2 jtc #include <dirent.h> 41 1.3.2.2 jtc #include <stdlib.h> 42 1.3.2.2 jtc #include <unistd.h> 43 1.3.2.2 jtc 44 1.3.2.2 jtc /* 45 1.3.2.2 jtc * The option SINGLEUSE may be defined to say that a telldir 46 1.3.2.2 jtc * cookie may be used only once before it is freed. This option 47 1.3.2.2 jtc * is used to avoid having memory usage grow without bound. 48 1.3.2.2 jtc */ 49 1.3.2.2 jtc #define SINGLEUSE 50 1.3.2.2 jtc 51 1.3.2.2 jtc /* 52 1.3.2.2 jtc * One of these structures is malloced to describe the current directory 53 1.3.2.2 jtc * position each time telldir is called. It records the current magic 54 1.3.2.2 jtc * cookie returned by getdirentries and the offset within the buffer 55 1.3.2.2 jtc * associated with that return value. 56 1.3.2.2 jtc */ 57 1.3.2.2 jtc struct ddloc { 58 1.3.2.2 jtc struct ddloc *loc_next;/* next structure in list */ 59 1.3.2.2 jtc long loc_index; /* key associated with structure */ 60 1.3.2.2 jtc long loc_seek; /* magic cookie returned by getdirentries */ 61 1.3.2.2 jtc long loc_loc; /* offset of entry in buffer */ 62 1.3.2.2 jtc }; 63 1.3.2.2 jtc 64 1.3.2.2 jtc #define NDIRHASH 32 /* Num of hash lists, must be a power of 2 */ 65 1.3.2.2 jtc #define LOCHASH(i) ((i)&(NDIRHASH-1)) 66 1.3.2.2 jtc 67 1.3.2.2 jtc static long dd_loccnt; /* Index of entry for sequential readdir's */ 68 1.3.2.2 jtc static struct ddloc *dd_hash[NDIRHASH]; /* Hash list heads for ddlocs */ 69 1.3.2.2 jtc 70 1.3.2.2 jtc /* 71 1.3.2.2 jtc * return a pointer into a directory 72 1.3.2.2 jtc */ 73 1.3.2.2 jtc long 74 1.3.2.2 jtc telldir(dirp) 75 1.3.2.2 jtc const DIR *dirp; 76 1.3.2.2 jtc { 77 1.3.2.2 jtc register int index; 78 1.3.2.2 jtc register struct ddloc *lp; 79 1.3.2.2 jtc 80 1.3.2.2 jtc if ((lp = (struct ddloc *)malloc(sizeof(struct ddloc))) == NULL) 81 1.3.2.2 jtc return (-1); 82 1.3.2.2 jtc index = dd_loccnt++; 83 1.3.2.2 jtc lp->loc_index = index; 84 1.3.2.2 jtc lp->loc_seek = dirp->dd_seek; 85 1.3.2.2 jtc lp->loc_loc = dirp->dd_loc; 86 1.3.2.2 jtc lp->loc_next = dd_hash[LOCHASH(index)]; 87 1.3.2.2 jtc dd_hash[LOCHASH(index)] = lp; 88 1.3.2.2 jtc return (index); 89 1.3.2.2 jtc } 90 1.3.2.2 jtc 91 1.3.2.2 jtc /* 92 1.3.2.2 jtc * seek to an entry in a directory. 93 1.3.2.2 jtc * Only values returned by "telldir" should be passed to seekdir. 94 1.3.2.2 jtc */ 95 1.3.2.2 jtc void 96 1.3.2.2 jtc __seekdir(dirp, loc) 97 1.3.2.2 jtc register DIR *dirp; 98 1.3.2.2 jtc long loc; 99 1.3.2.2 jtc { 100 1.3.2.2 jtc register struct ddloc *lp; 101 1.3.2.2 jtc register struct ddloc **prevlp; 102 1.3.2.2 jtc struct dirent *dp; 103 1.3.2.2 jtc 104 1.3.2.2 jtc prevlp = &dd_hash[LOCHASH(loc)]; 105 1.3.2.2 jtc lp = *prevlp; 106 1.3.2.2 jtc while (lp != NULL) { 107 1.3.2.2 jtc if (lp->loc_index == loc) 108 1.3.2.2 jtc break; 109 1.3.2.2 jtc prevlp = &lp->loc_next; 110 1.3.2.2 jtc lp = lp->loc_next; 111 1.3.2.2 jtc } 112 1.3.2.2 jtc if (lp == NULL) 113 1.3.2.2 jtc return; 114 1.3.2.2 jtc if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek) 115 1.3.2.2 jtc goto found; 116 1.3.2.2 jtc (void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET); 117 1.3.2.2 jtc dirp->dd_seek = lp->loc_seek; 118 1.3.2.2 jtc dirp->dd_loc = 0; 119 1.3.2.2 jtc while (dirp->dd_loc < lp->loc_loc) { 120 1.3.2.2 jtc dp = readdir(dirp); 121 1.3.2.2 jtc if (dp == NULL) 122 1.3.2.2 jtc break; 123 1.3.2.2 jtc } 124 1.3.2.2 jtc found: 125 1.3.2.2 jtc #ifdef SINGLEUSE 126 1.3.2.2 jtc *prevlp = lp->loc_next; 127 1.3.2.2 jtc free((caddr_t)lp); 128 1.3.2.2 jtc #endif 129 1.3.2.2 jtc } 130
Indexes created Thu Oct 02 14:10:14 GMT 2025