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 * 3. 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 * $FreeBSD: src/lib/libc/gen/opendir.c,v 1.10.2.1 2001/06/04 20:59:48 joerg Exp $
30 *
31 * @(#)opendir.c 8.8 (Berkeley) 5/1/95
32 */
33
34 #include "namespace.h"
35 #include <sys/param.h>
36 #include <sys/stat.h>
37
38 #include <dirent.h>
39 #include <errno.h>
40 #include <fcntl.h>
41 #include <stdlib.h>
42 #include <string.h>
43 #include <unistd.h>
44 #include "un-namespace.h"
45
46 #include "gen_private.h"
47
48 #define DEFAULT_FLAGS (DTF_HIDEW | DTF_NODUP)
49
50 /*
51 * Open a directory given its path.
52 */
53 DIR *
opendir(const char * name)54 opendir(const char *name)
55 {
56 return (__opendir2(name, DEFAULT_FLAGS));
57 }
58
59 /*
60 * Open a directory given a descriptor representing it.
61 */
62 DIR *
fdopendir(int fd)63 fdopendir(int fd)
64 {
65 return (__fdopendir2(fd, DEFAULT_FLAGS));
66 }
67
68 DIR *
__opendir2(const char * name,int flags)69 __opendir2(const char *name, int flags)
70 {
71 int fd;
72 struct stat statb;
73 DIR *dirp;
74 int saved_errno;
75
76 /*
77 * stat() before _open() because opening of special files may be
78 * harmful.
79 */
80 if (stat(name, &statb) != 0)
81 return (NULL);
82
83 fd = _open(name, O_RDONLY | O_NONBLOCK | O_DIRECTORY | O_CLOEXEC);
84 if (fd == -1)
85 return (NULL);
86 dirp = __fdopendir2(fd, flags);
87 if (dirp == NULL) {
88 saved_errno = errno;
89 _close(fd);
90 errno = saved_errno;
91 }
92
93 return (dirp);
94 }
95
96 DIR *
__fdopendir2(int fd,int flags)97 __fdopendir2(int fd, int flags)
98 {
99 DIR *dirp;
100 int incr;
101 int saved_errno;
102 struct stat statb;
103
104 dirp = NULL;
105
106 if (_fstat(fd, &statb) != 0)
107 goto fail;
108 if (!S_ISDIR(statb.st_mode)) {
109 errno = ENOTDIR;
110 goto fail;
111 }
112 if (_fcntl(fd, F_SETFD, FD_CLOEXEC) == -1 ||
113 (dirp = malloc(sizeof(DIR))) == NULL)
114 goto fail;
115
116 /*
117 * Use a multiple of DIRBLKSIZ. Make sure the buffer size is
118 * decent (at least 16K) to avoid unnecessary excess system calls.
119 */
120 incr = DIRBLKSIZ * 16;
121 if (incr < 16384)
122 incr = 16384;
123 if ((incr % DIRBLKSIZ) != 0)
124 incr = DIRBLKSIZ;
125
126 dirp->dd_len = incr;
127 dirp->dd_buf = malloc(dirp->dd_len);
128 if (dirp->dd_buf == NULL)
129 goto fail;
130 flags &= ~DTF_REWIND;
131
132 dirp->dd_loc = 0;
133 dirp->dd_fd = fd;
134 dirp->dd_flags = flags;
135 dirp->dd_lock = NULL;
136
137 /*
138 * Set up seek point for rewinddir.
139 */
140 dirp->dd_seek = 0;
141 dirp->dd_rewind = telldir(dirp);
142
143 /*
144 * The file offset of the fd passed to fdopendir() determines the
145 * initial entry returned by readdir(). Save this offset so that
146 * telldir() right after fdopendir() returns a value pointing to this
147 * initial entry.
148 * We don't have to worry about misaligned file offsets. The kernel
149 * deals with these.
150 */
151 if ((dirp->dd_seek = lseek(fd, 0, SEEK_CUR)) < 0)
152 goto fail;
153
154 return (dirp);
155
156 fail:
157 saved_errno = errno;
158 if (dirp != NULL) {
159 _reclaim_telldir(dirp);
160 free(dirp->dd_buf);
161 }
162 free(dirp);
163 errno = saved_errno;
164 return (NULL);
165 }
166