1/*	$OpenBSD: opendir.c,v 1.31 2024/04/15 15:47:58 florian 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/types.h>
32#include <sys/stat.h>
33
34#include <dirent.h>
35#include <errno.h>
36#include <fcntl.h>
37#include <stdlib.h>
38#include <unistd.h>
39
40#include "telldir.h"
41
42
43/*
44 * Open a directory specified by name.
45 */
46DIR *
47opendir(const char *name)
48{
49	DIR *dirp;
50	int fd;
51
52	if ((fd = open(name, O_RDONLY | O_DIRECTORY | O_CLOEXEC)) == -1)
53		return (NULL);
54	dirp = __fdopendir(fd);
55	if (dirp == NULL)
56		close(fd);
57	return (dirp);
58}
59DEF_WEAK(opendir);
60
61/*
62 * Open a directory specified by file descriptor.
63 */
64DIR *
65fdopendir(int fd)
66{
67	DIR *dirp;
68	int flags;
69
70	if ((flags = fcntl(fd, F_GETFL)) == -1)
71		return (NULL);
72	if ((flags & O_ACCMODE) != O_RDONLY && (flags & O_ACCMODE) != O_RDWR) {
73		errno = EBADF;
74		return (NULL);
75	}
76	dirp = __fdopendir(fd);
77	if (dirp != NULL) {
78		/* Record current offset for immediate telldir() */
79		dirp->dd_bufpos = dirp->dd_curpos = lseek(fd, 0, SEEK_CUR);
80
81		/*
82		 * POSIX doesn't require fdopendir() to set
83		 * FD_CLOEXEC, so it's okay for this to fail.
84		 */
85		(void)fcntl(fd, F_SETFD, FD_CLOEXEC);
86	}
87	return (dirp);
88}
89DEF_WEAK(fdopendir);
90
91DIR *
92__fdopendir(int fd)
93{
94	DIR *dirp;
95	struct stat sb;
96	int pageoffset;
97
98	if (fstat(fd, &sb))
99		return (NULL);
100	if (!S_ISDIR(sb.st_mode)) {
101		errno = ENOTDIR;
102		return (NULL);
103	}
104	if ((dirp = malloc(sizeof(DIR))) == NULL)
105		return (NULL);
106
107	pageoffset = getpagesize() - 1;
108	dirp->dd_len = ((int)sb.st_blksize * 4 + pageoffset) & ~pageoffset;
109	dirp->dd_buf = malloc(dirp->dd_len);
110	if (dirp->dd_buf == NULL) {
111		free(dirp);
112		return (NULL);
113	}
114
115	dirp->dd_size = 0;
116	dirp->dd_loc = 0;
117	dirp->dd_fd = fd;
118	dirp->dd_lock = NULL;
119	dirp->dd_curpos = 0;
120	dirp->dd_bufpos = 0;
121
122	return (dirp);
123}
124