2 * Copyright (c) 1983, 1993
3 * The Regents of the University of California. All rights reserved.
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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 $
34 * $DragonFly: src/lib/libc/gen/telldir.c,v 1.5 2007/11/21 05:48:31 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 off_t 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
80 telldir(const DIR *dirp
)
85 if ((lp
= (struct ddloc
*)malloc(sizeof(struct ddloc
))) == NULL
)
88 _pthread_mutex_lock((pthread_mutex_t
*)&dirp
->dd_lock
);
90 lp
->loc_index
= index
;
91 lp
->loc_seek
= dirp
->dd_seek
;
92 lp
->loc_loc
= dirp
->dd_loc
;
94 lp
->loc_next
= dd_hash
[LOCHASH(index
)];
95 dd_hash
[LOCHASH(index
)] = lp
;
97 _pthread_mutex_unlock((pthread_mutex_t
*)&dirp
->dd_lock
);
102 * seek to an entry in a directory.
103 * Only values returned by "telldir" should be passed to seekdir.
106 _seekdir(DIR *dirp
, long loc
)
109 struct ddloc
**prevlp
;
112 prevlp
= &dd_hash
[LOCHASH(loc
)];
115 if (lp
->loc_index
== loc
)
117 prevlp
= &lp
->loc_next
;
122 if (lp
->loc_loc
== dirp
->dd_loc
&& lp
->loc_seek
== dirp
->dd_seek
)
124 lseek(dirp
->dd_fd
, lp
->loc_seek
, SEEK_SET
);
125 dirp
->dd_seek
= lp
->loc_seek
;
127 while (dirp
->dd_loc
< lp
->loc_loc
) {
128 dp
= _readdir_unlocked(dirp
);
134 *prevlp
= lp
->loc_next
;
140 * Reclaim memory for telldir cookies which weren't used.
143 _reclaim_telldir(DIR *dirp
)
146 struct ddloc
**prevlp
;
149 for (i
= 0; i
< NDIRHASH
; i
++) {
150 prevlp
= &dd_hash
[i
];
153 if (lp
->loc_dirp
== dirp
) {
154 *prevlp
= lp
->loc_next
;
159 prevlp
= &lp
->loc_next
;