Commit | Line | Data |
---|---|---|
15637ed4 RG |
1 | /* |
2 | * Copyright (c) 1983 Regents of the University of California. | |
3 | * 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 | * 3. All advertising materials mentioning features or use of this software | |
14 | * must display the following acknowledgement: | |
15 | * This product includes software developed by the University of | |
16 | * California, Berkeley and its contributors. | |
17 | * 4. Neither the name of the University nor the names of its contributors | |
18 | * may be used to endorse or promote products derived from this software | |
19 | * without specific prior written permission. | |
20 | * | |
21 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
22 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
23 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
24 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
25 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
26 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
27 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
28 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
29 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
30 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
31 | * SUCH DAMAGE. | |
32 | */ | |
33 | ||
34 | #if defined(LIBC_SCCS) && !defined(lint) | |
35 | static char sccsid[] = "@(#)telldir.c 5.9 (Berkeley) 2/23/91"; | |
36 | #endif /* LIBC_SCCS and not lint */ | |
37 | ||
38 | #include <sys/param.h> | |
39 | #include <dirent.h> | |
40 | #include <stdlib.h> | |
41 | #include <unistd.h> | |
42 | ||
43 | /* | |
44 | * The option SINGLEUSE may be defined to say that a telldir | |
45 | * cookie may be used only once before it is freed. This option | |
46 | * is used to avoid having memory usage grow without bound. | |
47 | */ | |
48 | #define SINGLEUSE | |
49 | ||
50 | /* | |
51 | * One of these structures is malloced to describe the current directory | |
52 | * position each time telldir is called. It records the current magic | |
53 | * cookie returned by getdirentries and the offset within the buffer | |
54 | * associated with that return value. | |
55 | */ | |
56 | struct ddloc { | |
57 | struct ddloc *loc_next;/* next structure in list */ | |
58 | long loc_index; /* key associated with structure */ | |
59 | long loc_seek; /* magic cookie returned by getdirentries */ | |
60 | long loc_loc; /* offset of entry in buffer */ | |
61 | }; | |
62 | ||
63 | #define NDIRHASH 32 /* Num of hash lists, must be a power of 2 */ | |
64 | #define LOCHASH(i) ((i)&(NDIRHASH-1)) | |
65 | ||
66 | static long dd_loccnt; /* Index of entry for sequential readdir's */ | |
67 | static struct ddloc *dd_hash[NDIRHASH]; /* Hash list heads for ddlocs */ | |
68 | ||
69 | /* | |
70 | * return a pointer into a directory | |
71 | */ | |
72 | long | |
73 | telldir(dirp) | |
74 | const DIR *dirp; | |
75 | { | |
76 | register int index; | |
77 | register struct ddloc *lp; | |
78 | ||
79 | if ((lp = (struct ddloc *)malloc(sizeof(struct ddloc))) == NULL) | |
80 | return (-1); | |
81 | index = dd_loccnt++; | |
82 | lp->loc_index = index; | |
83 | lp->loc_seek = dirp->dd_seek; | |
84 | lp->loc_loc = dirp->dd_loc; | |
85 | lp->loc_next = dd_hash[LOCHASH(index)]; | |
86 | dd_hash[LOCHASH(index)] = lp; | |
87 | return (index); | |
88 | } | |
89 | ||
90 | /* | |
91 | * seek to an entry in a directory. | |
92 | * Only values returned by "telldir" should be passed to seekdir. | |
93 | */ | |
94 | void | |
95 | _seekdir(dirp, loc) | |
96 | register DIR *dirp; | |
97 | long loc; | |
98 | { | |
99 | register struct ddloc *lp; | |
100 | register struct ddloc **prevlp; | |
101 | struct dirent *dp; | |
102 | extern long lseek(); | |
103 | ||
104 | prevlp = &dd_hash[LOCHASH(loc)]; | |
105 | lp = *prevlp; | |
106 | while (lp != NULL) { | |
107 | if (lp->loc_index == loc) | |
108 | break; | |
109 | prevlp = &lp->loc_next; | |
110 | lp = lp->loc_next; | |
111 | } | |
112 | if (lp == NULL) | |
113 | return; | |
114 | if (lp->loc_loc == dirp->dd_loc && lp->loc_seek == dirp->dd_seek) | |
115 | goto found; | |
116 | (void) lseek(dirp->dd_fd, lp->loc_seek, 0); | |
117 | dirp->dd_seek = lp->loc_seek; | |
118 | dirp->dd_loc = 0; | |
119 | while (dirp->dd_loc < lp->loc_loc) { | |
120 | dp = readdir(dirp); | |
121 | if (dp == NULL) | |
122 | break; | |
123 | } | |
124 | found: | |
125 | #ifdef SINGLEUSE | |
126 | *prevlp = lp->loc_next; | |
127 | free((caddr_t)lp); | |
128 | #endif | |
129 | } |