xref: /freebsd/lib/libc/gen/telldir.c (revision a3cbca537ef1d8ac03a693cd51d98fb8087acc8d)
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  * 4. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #if defined(LIBC_SCCS) && !defined(lint)
31 static char sccsid[] = "@(#)telldir.c	8.1 (Berkeley) 6/4/93";
32 #endif /* LIBC_SCCS and not lint */
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
35 
36 #include "namespace.h"
37 #include <sys/param.h>
38 #include <sys/queue.h>
39 #include <dirent.h>
40 #include <pthread.h>
41 #include <stdlib.h>
42 #include <unistd.h>
43 #include "un-namespace.h"
44 
45 #include "libc_private.h"
46 #include "gen-private.h"
47 #include "telldir.h"
48 
49 /*
50  * return a pointer into a directory
51  */
52 long
53 telldir(dirp)
54 	DIR *dirp;
55 {
56 	struct ddloc *lp;
57 	long idx;
58 
59 	if (__isthreaded)
60 		_pthread_mutex_lock(&dirp->dd_lock);
61 	LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
62 		if (lp->loc_seek == dirp->dd_seek &&
63 		    lp->loc_loc == dirp->dd_loc)
64 			break;
65 	}
66 	if (lp == NULL) {
67 		lp = malloc(sizeof(struct ddloc));
68 		if (lp == NULL) {
69 			if (__isthreaded)
70 				_pthread_mutex_unlock(&dirp->dd_lock);
71 			return (-1);
72 		}
73 		lp->loc_index = dirp->dd_td->td_loccnt++;
74 		lp->loc_seek = dirp->dd_seek;
75 		lp->loc_loc = dirp->dd_loc;
76 		LIST_INSERT_HEAD(&dirp->dd_td->td_locq, lp, loc_lqe);
77 	}
78 	idx = lp->loc_index;
79 	if (__isthreaded)
80 		_pthread_mutex_unlock(&dirp->dd_lock);
81 	return (idx);
82 }
83 
84 /*
85  * seek to an entry in a directory.
86  * Only values returned by "telldir" should be passed to seekdir.
87  */
88 void
89 _seekdir(dirp, loc)
90 	DIR *dirp;
91 	long loc;
92 {
93 	struct ddloc *lp;
94 	struct dirent *dp;
95 
96 	LIST_FOREACH(lp, &dirp->dd_td->td_locq, loc_lqe) {
97 		if (lp->loc_index == loc)
98 			break;
99 	}
100 	if (lp == NULL)
101 		return;
102 	if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek)
103 		return;
104 	(void) lseek(dirp->dd_fd, (off_t)lp->loc_seek, SEEK_SET);
105 	dirp->dd_seek = lp->loc_seek;
106 	dirp->dd_loc = 0;
107 	while (dirp->dd_loc < lp->loc_loc) {
108 		dp = _readdir_unlocked(dirp, 0);
109 		if (dp == NULL)
110 			break;
111 	}
112 }
113 
114 /*
115  * Reclaim memory for telldir cookies which weren't used.
116  */
117 void
118 _reclaim_telldir(dirp)
119 	DIR *dirp;
120 {
121 	struct ddloc *lp;
122 	struct ddloc *templp;
123 
124 	lp = LIST_FIRST(&dirp->dd_td->td_locq);
125 	while (lp != NULL) {
126 		templp = lp;
127 		lp = LIST_NEXT(lp, loc_lqe);
128 		free(templp);
129 	}
130 	LIST_INIT(&dirp->dd_td->td_locq);
131 }
132