xref: /netbsd-src/lib/libc/gen/opendir.c (revision ae1bfcddc410612bc8c58b807e1830becb69a24c)
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[] = "@(#)opendir.c	5.11 (Berkeley) 2/23/91";
36 #endif /* LIBC_SCCS and not lint */
37 
38 #include <sys/param.h>
39 #include <dirent.h>
40 #include <fcntl.h>
41 #include <stdlib.h>
42 #include <unistd.h>
43 
44 long _rewinddir;
45 
46 /*
47  * open a directory.
48  */
49 DIR *
50 opendir(name)
51 	const char *name;
52 {
53 	register DIR *dirp;
54 	register int fd;
55 
56 	if ((fd = open(name, 0)) == -1)
57 		return NULL;
58 	if (fcntl(fd, F_SETFD, 1) == -1 ||
59 	    (dirp = (DIR *)malloc(sizeof(DIR))) == NULL) {
60 		close (fd);
61 		return NULL;
62 	}
63 	/*
64 	 * If CLSIZE is an exact multiple of DIRBLKSIZ, use a CLSIZE
65 	 * buffer that it cluster boundary aligned.
66 	 * Hopefully this can be a big win someday by allowing page trades
67 	 * to user space to be done by getdirentries()
68 	 */
69 	if ((CLSIZE % DIRBLKSIZ) == 0) {
70 		dirp->dd_buf = malloc(CLSIZE);
71 		dirp->dd_len = CLSIZE;
72 	} else {
73 		dirp->dd_buf = malloc(DIRBLKSIZ);
74 		dirp->dd_len = DIRBLKSIZ;
75 	}
76 	if (dirp->dd_buf == NULL) {
77 		close (fd);
78 		return NULL;
79 	}
80 	dirp->dd_fd = fd;
81 	dirp->dd_loc = 0;
82 	dirp->dd_seek = 0;
83 	/*
84 	 * Set up seek point for rewinddir.
85 	 */
86 	_rewinddir = telldir(dirp);
87 	return dirp;
88 }
89