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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 $
34 * $DragonFly: src/lib/libc/gen/telldir.c,v 1.3 2005/01/31 22:29:15 dillon Exp $
36 * @(#)telldir.c 8.1 (Berkeley) 6/4/93
39 #include "namespace.h"
40 #include <sys/param.h>
45 #include "un-namespace.h"
47 #include "libc_private.h"
50 * The option SINGLEUSE may be defined to say that a telldir
51 * cookie may be used only once before it is freed. This option
52 * is used to avoid having memory usage grow without bound.
57 * One of these structures is malloced to describe the current directory
58 * position each time telldir is called. It records the current magic
59 * cookie returned by getdirentries and the offset within the buffer
60 * associated with that return value.
63 struct ddloc *loc_next;/* next structure in list */
64 long loc_index; /* key associated with structure */
65 long loc_seek; /* magic cookie returned by getdirentries */
66 long loc_loc; /* offset of entry in buffer */
67 const DIR* loc_dirp; /* directory which used this entry */
70 #define NDIRHASH 32 /* Num of hash lists, must be a power of 2 */
71 #define LOCHASH(i) ((i)&(NDIRHASH-1))
73 static long dd_loccnt; /* Index of entry for sequential readdir's */
74 static struct ddloc *dd_hash[NDIRHASH]; /* Hash list heads for ddlocs */
77 * return a pointer into a directory
86 if ((lp = (struct ddloc *)malloc(sizeof(struct ddloc))) == NULL)
89 _pthread_mutex_lock((pthread_mutex_t *)&dirp->dd_lock);
91 lp->loc_index = index;
92 lp->loc_seek = dirp->dd_seek;
93 lp->loc_loc = dirp->dd_loc;
95 lp->loc_next = dd_hash[LOCHASH(index)];
96 dd_hash[LOCHASH(index)] = lp;
98 _pthread_mutex_unlock((pthread_mutex_t *)&dirp->dd_lock);
103 * seek to an entry in a directory.
104 * Only values returned by "telldir" should be passed to seekdir.
112 struct ddloc **prevlp;
115 prevlp = &dd_hash[LOCHASH(loc)];
118 if (lp->loc_index == loc)
120 prevlp = &lp->loc_next;
125 if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek)
127 (void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET);
128 dirp->dd_seek = lp->loc_seek;
130 while (dirp->dd_loc < lp->loc_loc) {
131 dp = _readdir_unlocked(dirp);
137 *prevlp = lp->loc_next;
143 * Reclaim memory for telldir cookies which weren't used.
146 _reclaim_telldir(dirp)
150 struct ddloc **prevlp;
153 for (i = 0; i < NDIRHASH; i++) {
154 prevlp = &dd_hash[i];
157 if (lp->loc_dirp == dirp) {
158 *prevlp = lp->loc_next;
163 prevlp = &lp->loc_next;