[444] | 1 | #ifndef HAVE_OPENDIR |
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| 2 | |
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| 3 | /* |
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| 4 | * Copyright (c) 1983 Regents of the University of California. |
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| 5 | * All rights reserved. |
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| 6 | * |
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| 7 | * Redistribution and use in source and binary forms, with or without |
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| 8 | * modification, are permitted provided that the following conditions |
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| 9 | * are met: |
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| 10 | * 1. Redistributions of source code must retain the above copyright |
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| 11 | * notice, this list of conditions and the following disclaimer. |
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| 12 | * 2. Redistributions in binary form must reproduce the above copyright |
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| 13 | * notice, this list of conditions and the following disclaimer in the |
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| 14 | * documentation and/or other materials provided with the distribution. |
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| 15 | * 3. All advertising materials mentioning features or use of this software |
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| 16 | * must display the following acknowledgement: |
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| 17 | * This product includes software developed by the University of |
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| 18 | * California, Berkeley and its contributors. |
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| 19 | * 4. Neither the name of the University nor the names of its contributors |
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| 20 | * may be used to endorse or promote products derived from this software |
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| 21 | * without specific prior written permission. |
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| 22 | * |
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| 23 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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| 24 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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| 25 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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| 26 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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| 27 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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| 28 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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| 29 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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| 30 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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| 31 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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| 32 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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| 33 | * SUCH DAMAGE. |
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| 34 | */ |
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| 35 | |
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| 36 | #if defined(LIBC_SCCS) && !defined(lint) |
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| 37 | static char sccsid[] = "@(#)telldir.c 5.9 (Berkeley) 2/23/91"; |
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| 38 | #endif /* LIBC_SCCS and not lint */ |
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| 39 | |
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| 40 | #include <sys/param.h> |
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| 41 | #include <dirent.h> |
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| 42 | #include <stdlib.h> |
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| 43 | #include <unistd.h> |
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| 44 | #include <sys/lock.h> |
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| 45 | |
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| 46 | /* |
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| 47 | * The option SINGLEUSE may be defined to say that a telldir |
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| 48 | * cookie may be used only once before it is freed. This option |
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| 49 | * is used to avoid having memory usage grow without bound. |
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| 50 | */ |
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| 51 | #define SINGLEUSE |
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| 52 | |
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| 53 | /* |
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| 54 | * One of these structures is malloced to describe the current directory |
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| 55 | * position each time telldir is called. It records the current magic |
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| 56 | * cookie returned by getdirentries and the offset within the buffer |
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| 57 | * associated with that return value. |
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| 58 | */ |
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| 59 | struct ddloc { |
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| 60 | struct ddloc *loc_next;/* next structure in list */ |
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| 61 | long loc_index; /* key associated with structure */ |
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| 62 | long loc_seek; /* magic cookie returned by getdirentries */ |
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| 63 | long loc_loc; /* offset of entry in buffer */ |
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| 64 | DIR *loc_dirp; /* DIR pointer */ |
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| 65 | }; |
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| 66 | |
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| 67 | #define NDIRHASH 32 /* Num of hash lists, must be a power of 2 */ |
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| 68 | #define LOCHASH(i) ((i)&(NDIRHASH-1)) |
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| 69 | |
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| 70 | static long dd_loccnt = 1; /* Index of entry for sequential readdir's */ |
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| 71 | static struct ddloc *dd_hash[NDIRHASH]; /* Hash list heads for ddlocs */ |
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| 72 | |
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| 73 | #if !defined(__SINGLE_THREAD__) && defined(HAVE_DD_LOCK) |
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| 74 | __LOCK_INIT(static, __dd_hash_mutex); |
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| 75 | #endif |
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| 76 | |
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| 77 | /* |
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| 78 | * return a pointer into a directory |
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| 79 | */ |
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| 80 | |
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| 81 | #if !defined(_ELIX_LEVEL) || (_ELIX_LEVEL >= 2) |
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| 82 | |
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| 83 | long |
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| 84 | telldir (DIR *dirp) |
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| 85 | { |
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| 86 | register int index; |
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| 87 | register struct ddloc *lp; |
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| 88 | |
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| 89 | if ((lp = (struct ddloc *)malloc(sizeof(struct ddloc))) == NULL) |
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| 90 | return (-1); |
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| 91 | |
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| 92 | #ifdef HAVE_DD_LOCK |
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| 93 | __lock_acquire_recursive(dirp->dd_lock); |
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| 94 | #ifndef __SINGLE_THREAD__ |
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| 95 | __lock_acquire(__dd_hash_mutex); |
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| 96 | #endif |
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| 97 | #endif |
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| 98 | index = dd_loccnt++; |
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| 99 | lp->loc_index = index; |
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| 100 | lp->loc_seek = dirp->dd_seek; |
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| 101 | lp->loc_loc = dirp->dd_loc; |
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| 102 | lp->loc_dirp = dirp; |
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| 103 | lp->loc_next = dd_hash[LOCHASH(index)]; |
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| 104 | dd_hash[LOCHASH(index)] = lp; |
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| 105 | #ifdef HAVE_DD_LOCK |
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| 106 | #ifndef __SINGLE_THREAD__ |
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| 107 | __lock_release(__dd_hash_mutex); |
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| 108 | #endif |
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| 109 | __lock_release_recursive(dirp->dd_lock); |
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| 110 | #endif |
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| 111 | return (index); |
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| 112 | } |
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| 113 | |
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| 114 | #endif /* !_ELIX_LEVEL || _ELIX_LEVEL >= 2 */ |
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| 115 | |
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| 116 | /* |
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| 117 | * seek to an entry in a directory. |
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| 118 | * Only values returned by "telldir" should be passed to seekdir. |
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| 119 | */ |
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| 120 | void |
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| 121 | _seekdir (register DIR *dirp, |
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| 122 | long loc) |
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| 123 | { |
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| 124 | register struct ddloc *lp; |
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| 125 | register struct ddloc **prevlp; |
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| 126 | struct dirent *dp; |
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| 127 | |
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| 128 | #if !defined(__SINGLE_THREAD__) && defined(HAVE_DD_LOCK) |
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| 129 | __lock_acquire(__dd_hash_mutex); |
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| 130 | #endif |
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| 131 | if (loc != 0) { |
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| 132 | prevlp = &dd_hash[LOCHASH(loc)]; |
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| 133 | lp = *prevlp; |
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| 134 | while (lp != NULL) { |
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| 135 | if (lp->loc_index == loc) |
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| 136 | break; |
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| 137 | prevlp = &lp->loc_next; |
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| 138 | lp = lp->loc_next; |
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| 139 | } |
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| 140 | if (lp == NULL) { |
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| 141 | #if !defined(__SINGLE_THREAD__) && defined(HAVE_DD_LOCK) |
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| 142 | __lock_release(__dd_hash_mutex); |
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| 143 | #endif |
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| 144 | return; |
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| 145 | } |
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| 146 | if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek) |
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| 147 | goto found; |
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| 148 | (void) lseek(dirp->dd_fd, lp->loc_seek, 0); |
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| 149 | dirp->dd_seek = lp->loc_seek; |
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| 150 | dirp->dd_loc = 0; |
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| 151 | while (dirp->dd_loc < lp->loc_loc) { |
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| 152 | dp = readdir(dirp); |
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| 153 | if (dp == NULL) |
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| 154 | break; |
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| 155 | } |
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| 156 | found: |
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| 157 | #ifdef SINGLEUSE |
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| 158 | *prevlp = lp->loc_next; |
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| 159 | free((caddr_t)lp); |
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| 160 | #endif |
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| 161 | } else { |
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| 162 | // loc 0 means rewinding |
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| 163 | (void) lseek(dirp->dd_fd, 0, 0); |
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| 164 | dirp->dd_seek = 0; |
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| 165 | dirp->dd_loc = 0; |
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| 166 | } |
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| 167 | #if !defined(__SINGLE_THREAD__) && defined(HAVE_DD_LOCK) |
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| 168 | __lock_release(__dd_hash_mutex); |
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| 169 | #endif |
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| 170 | } |
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| 171 | |
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| 172 | /* clean out any hash entries from a closed directory */ |
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| 173 | void |
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| 174 | _cleanupdir (register DIR *dirp) |
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| 175 | { |
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| 176 | int i; |
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| 177 | |
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| 178 | #if !defined(__SINGLE_THREAD__) && defined(HAVE_DD_LOCK) |
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| 179 | __lock_acquire(__dd_hash_mutex); |
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| 180 | #endif |
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| 181 | for (i = 0; i < NDIRHASH; ++i) { |
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| 182 | struct ddloc head; |
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| 183 | register struct ddloc *lp; |
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| 184 | register struct ddloc *prevlp; |
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| 185 | |
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| 186 | lp = dd_hash[i]; |
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| 187 | head.loc_next = lp; |
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| 188 | prevlp = &head; |
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| 189 | while (lp != NULL) { |
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| 190 | struct ddloc *nextlp; |
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| 191 | |
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| 192 | nextlp = lp->loc_next; |
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| 193 | if (lp->loc_dirp == dirp) { |
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| 194 | prevlp->loc_next = nextlp; |
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| 195 | free((caddr_t)lp); |
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| 196 | } |
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| 197 | else |
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| 198 | prevlp = lp; |
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| 199 | lp = nextlp; |
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| 200 | } |
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| 201 | dd_hash[i] = head.loc_next; |
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| 202 | } |
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| 203 | #if !defined(__SINGLE_THREAD__) && defined(HAVE_DD_LOCK) |
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| 204 | __lock_release(__dd_hash_mutex); |
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| 205 | #endif |
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| 206 | |
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| 207 | } |
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| 208 | #endif /* ! HAVE_OPENDIR */ |
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