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 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE.
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32 * 33 * $FreeBSD: head/lib/libc/gen/telldir.c 69656 2000-12-06 03:15:49Z deischen $ |
34 */ 35 36#if defined(LIBC_SCCS) && !defined(lint) 37static char sccsid[] = "@(#)telldir.c 8.1 (Berkeley) 6/4/93"; 38#endif /* LIBC_SCCS and not lint */ 39 40#include <sys/param.h> 41#include <dirent.h> 42#include <stdlib.h> 43#include <unistd.h> 44 45/* 46 * The option SINGLEUSE may be defined to say that a telldir 47 * cookie may be used only once before it is freed. This option 48 * is used to avoid having memory usage grow without bound. 49 */ 50#define SINGLEUSE 51 52/* 53 * One of these structures is malloced to describe the current directory 54 * position each time telldir is called. It records the current magic 55 * cookie returned by getdirentries and the offset within the buffer 56 * associated with that return value. 57 */
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56struct ddloc {
57 struct ddloc *loc_next;/* next structure in list */
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58struct _ddloc { 59 LIST_ENTRY(_ddloc) loc_lqe; /* entry in list */ |
60 long loc_index; /* key associated with structure */ 61 long loc_seek; /* magic cookie returned by getdirentries */ 62 long loc_loc; /* offset of entry in buffer */
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61 const DIR* loc_dirp; /* directory which used this entry */
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63}; 64
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64#define NDIRHASH 32 /* Num of hash lists, must be a power of 2 */
65#define LOCHASH(i) ((i)&(NDIRHASH-1))
66
67static long dd_loccnt; /* Index of entry for sequential readdir's */
68static struct ddloc *dd_hash[NDIRHASH]; /* Hash list heads for ddlocs */
69
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65/* 66 * return a pointer into a directory 67 */ 68long 69telldir(dirp)
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75 const DIR *dirp;
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70 DIR *dirp; |
71{
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77 register int index;
78 register struct ddloc *lp;
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72 struct _ddloc *lp; |
73
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80 if ((lp = (struct ddloc *)malloc(sizeof(struct ddloc))) == NULL)
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74 if ((lp = (struct _ddloc *)malloc(sizeof(struct _ddloc))) == NULL) |
75 return (-1);
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82 index = dd_loccnt++;
83 lp->loc_index = index;
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76 lp->loc_index = dirp->dd_loccnt++; |
77 lp->loc_seek = dirp->dd_seek; 78 lp->loc_loc = dirp->dd_loc;
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86 lp->loc_dirp = dirp;
87 lp->loc_next = dd_hash[LOCHASH(index)];
88 dd_hash[LOCHASH(index)] = lp;
89 return (index);
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79 LIST_INSERT_HEAD(&dirp->dd_locq, lp, loc_lqe); 80 return (lp->loc_index); |
81} 82 83/* 84 * seek to an entry in a directory. 85 * Only values returned by "telldir" should be passed to seekdir. 86 */ 87void 88_seekdir(dirp, loc)
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98 register DIR *dirp;
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89 DIR *dirp; |
90 long loc; 91{
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101 register struct ddloc *lp;
102 register struct ddloc **prevlp;
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92 struct _ddloc *lp; |
93 struct dirent *dp; 94
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105 prevlp = &dd_hash[LOCHASH(loc)];
106 lp = *prevlp;
107 while (lp != NULL) {
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95 LIST_FOREACH(lp, &dirp->dd_locq, loc_lqe) { |
96 if (lp->loc_index == loc) 97 break;
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110 prevlp = &lp->loc_next;
111 lp = lp->loc_next;
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98 } 99 if (lp == NULL) 100 return; 101 if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek) 102 goto found; 103 (void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET); 104 dirp->dd_seek = lp->loc_seek; 105 dirp->dd_loc = 0; 106 while (dirp->dd_loc < lp->loc_loc) { 107 dp = readdir(dirp); 108 if (dp == NULL) 109 break; 110 } 111found: 112#ifdef SINGLEUSE
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127 *prevlp = lp->loc_next;
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113 LIST_REMOVE(lp, loc_lqe); |
114 free((caddr_t)lp); 115#endif 116} 117 118/* 119 * Reclaim memory for telldir cookies which weren't used. 120 */ 121void 122_reclaim_telldir(dirp)
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137 register const DIR *dirp;
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123 DIR *dirp; |
124{
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139 register struct ddloc *lp;
140 register struct ddloc **prevlp;
141 int i;
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125 struct _ddloc *lp; 126 struct _ddloc *templp; |
127
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143 for (i = 0; i < NDIRHASH; i++) {
144 prevlp = &dd_hash[i];
145 lp = *prevlp;
146 while (lp != NULL) {
147 if (lp->loc_dirp == dirp) {
148 *prevlp = lp->loc_next;
149 free((caddr_t)lp);
150 lp = *prevlp;
151 continue;
152 }
153 prevlp = &lp->loc_next;
154 lp = lp->loc_next;
155 }
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128 lp = LIST_FIRST(&dirp->dd_locq); 129 while (lp != NULL) { 130 templp = lp; 131 lp = LIST_NEXT(lp, loc_lqe); 132 free(templp); |
133 }
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134 LIST_INIT(&dirp->dd_locq); |
135}
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