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
40struct _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 *
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 */
83int
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 */
98struct dirent *
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