opendir.c revision 7978 
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. 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)
35static char sccsid[] = "@(#)opendir.c	8.2 (Berkeley) 2/12/94";
36#endif /* LIBC_SCCS and not lint */
37
38#include <sys/param.h>
39#include <sys/stat.h>
40
41#include <dirent.h>
42#include <errno.h>
43#include <fcntl.h>
44#include <stdlib.h>
45#include <unistd.h>
46
47/*
48 * open a directory.
49 */
50DIR *
51opendir(name)
52	const char *name;
53{
54	register DIR *dirp;
55	register int fd;
56	int saved_errno;
57	struct stat sb;
58
59	if ((fd = open(name, O_RDONLY | O_NONBLOCK)) == -1)
60		return NULL;
61	dirp = NULL;
62	if (fstat(fd, &sb) != 0)
63		goto fail;
64	if (!S_ISDIR(sb.st_mode)) {
65		errno = ENOTDIR;
66		goto fail;
67	}
68	if (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1 ||
69	    (dirp = malloc(sizeof(DIR))) == NULL)
70		goto fail;
71	/*
72	 * If CLBYTES is an exact multiple of DIRBLKSIZ, use a CLBYTES
73	 * buffer that it cluster boundary aligned.
74	 * Hopefully this can be a big win someday by allowing page trades
75	 * to user space to be done by getdirentries()
76	 */
77	if ((CLBYTES % DIRBLKSIZ) == 0) {
78		dirp->dd_buf = malloc(CLBYTES);
79		dirp->dd_len = CLBYTES;
80	} else {
81		dirp->dd_buf = malloc(DIRBLKSIZ);
82		dirp->dd_len = DIRBLKSIZ;
83	}
84	if (dirp->dd_buf == NULL)
85		goto fail;
86	dirp->dd_fd = fd;
87	dirp->dd_loc = 0;
88	dirp->dd_seek = 0;
89	/*
90	 * Set up seek point for rewinddir.
91	 */
92	dirp->dd_rewind = telldir(dirp);
93	return dirp;
94
95fail:
96	saved_errno = errno;
97	free(dirp);
98	close(fd);
99	errno = saved_errno;
100	return NULL;
101}
102