2 * Copyright (c) 1983, 1993
3 * The Regents of the University of California. All rights reserved.
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6 * modification, are permitted provided that the following conditions
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14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
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33 * $FreeBSD: src/lib/libc/gen/telldir.c,v 1.4.12.1 2001/03/05 09:39:59 obrien Exp $
36 #if defined(LIBC_SCCS) && !defined(lint)
37 static char sccsid[] = "@(#)telldir.c 8.1 (Berkeley) 6/4/93";
38 #endif /* LIBC_SCCS and not lint */
40 #include <sys/param.h>
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.
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.
59 struct ddloc *loc_next;/* next structure 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 */
63 const DIR* loc_dirp; /* directory which used this entry */
66 #define NDIRHASH 32 /* Num of hash lists, must be a power of 2 */
67 #define LOCHASH(i) ((i)&(NDIRHASH-1))
69 static long dd_loccnt; /* Index of entry for sequential readdir's */
70 static struct ddloc *dd_hash[NDIRHASH]; /* Hash list heads for ddlocs */
73 * return a pointer into a directory
82 if ((lp = (struct ddloc *)malloc(sizeof(struct ddloc))) == NULL)
85 lp->loc_index = index;
86 lp->loc_seek = dirp->dd_seek;
87 lp->loc_loc = dirp->dd_loc;
89 lp->loc_next = dd_hash[LOCHASH(index)];
90 dd_hash[LOCHASH(index)] = lp;
95 * seek to an entry in a directory.
96 * Only values returned by "telldir" should be passed to seekdir.
104 struct ddloc **prevlp;
107 prevlp = &dd_hash[LOCHASH(loc)];
110 if (lp->loc_index == loc)
112 prevlp = &lp->loc_next;
117 if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek)
119 (void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET);
120 dirp->dd_seek = lp->loc_seek;
122 while (dirp->dd_loc < lp->loc_loc) {
129 *prevlp = lp->loc_next;
135 * Reclaim memory for telldir cookies which weren't used.
138 _reclaim_telldir(dirp)
142 struct ddloc **prevlp;
145 for (i = 0; i < NDIRHASH; i++) {
146 prevlp = &dd_hash[i];
149 if (lp->loc_dirp == dirp) {
150 *prevlp = lp->loc_next;
155 prevlp = &lp->loc_next;