1 /* $OpenBSD: dir.c,v 1.25 2022/01/08 06:49:41 guenther Exp $ */
2 /*
3 * Copyright (c) 1983, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 * may be used to endorse or promote products derived from this software
16 * without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31 #include <sys/stat.h>
32
33 #include <dirent.h>
34 #include <fcntl.h>
35
36 #include "syscall.h"
37 #include "util.h"
38 #include "dir.h"
39
40 struct _dl_dirdesc {
41 long dd_loc; /* offset in current buffer */
42 long dd_size; /* amount of data returned by getdents() */
43 char *dd_buf; /* data buffer */
44 int dd_len; /* size of data buffer */
45 int dd_fd; /* file descriptor associated with directory */
46 };
47
48 /*
49 * Open a directory.
50 */
51 _dl_DIR *
_dl_opendir(const char * name)52 _dl_opendir(const char *name)
53 {
54 _dl_DIR *dirp;
55 int fd;
56 struct stat sb;
57
58 if ((fd = _dl_open(name, O_RDONLY | O_DIRECTORY | O_CLOEXEC)) < 0)
59 return (NULL);
60 if (_dl_fstat(fd, &sb) || (dirp = _dl_malloc(sizeof(*dirp))) == NULL) {
61 _dl_close(fd);
62 return (NULL);
63 }
64
65 dirp->dd_fd = fd;
66 dirp->dd_loc = 0;
67 dirp->dd_size = 0;
68 dirp->dd_len = _dl_round_page(sb.st_blksize);
69 dirp->dd_buf = _dl_malloc(dirp->dd_len);
70 if (dirp->dd_buf == NULL) {
71 _dl_free(dirp);
72 _dl_close(fd);
73 return (NULL);
74 }
75
76 return (dirp);
77 }
78
79
80 /*
81 * close a directory.
82 */
83 int
_dl_closedir(_dl_DIR * dirp)84 _dl_closedir(_dl_DIR *dirp)
85 {
86 int ret;
87
88 ret = _dl_close(dirp->dd_fd);
89 _dl_free(dirp->dd_buf);
90 _dl_free(dirp);
91 return ret;
92 }
93
94
95 /*
96 * get next entry in a directory.
97 */
98 struct dirent *
_dl_readdir(_dl_DIR * dirp)99 _dl_readdir(_dl_DIR *dirp)
100 {
101 struct dirent *dp;
102
103 for (;;) {
104 if (dirp->dd_loc >= dirp->dd_size) {
105 dirp->dd_loc = 0;
106 }
107 if (dirp->dd_loc == 0) {
108 dirp->dd_size = _dl_getdents(dirp->dd_fd,
109 dirp->dd_buf, dirp->dd_len);
110 if (dirp->dd_size <= 0)
111 return (NULL);
112 }
113 dp = (struct dirent *)(dirp->dd_buf + dirp->dd_loc);
114 if ((long)dp & 03) /* bogus pointer check */
115 return (NULL);
116 if (dp->d_reclen <= 0 ||
117 dp->d_reclen > dirp->dd_len + 1 - dirp->dd_loc)
118 return (NULL);
119 dirp->dd_loc += dp->d_reclen;
120 if (dp->d_ino == 0)
121 continue;
122 return (dp);
123 }
124 }
125