xref: /freebsd/lib/libc/gen/readdir.c (revision 4f52dfbb8d6c4d446500c5b097e3806ec219fbd4)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 1983, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 
32 #if defined(LIBC_SCCS) && !defined(lint)
33 static char sccsid[] = "@(#)readdir.c	8.3 (Berkeley) 9/29/94";
34 #endif /* LIBC_SCCS and not lint */
35 #include <sys/cdefs.h>
36 __FBSDID("$FreeBSD$");
37 
38 #include "namespace.h"
39 #include <sys/param.h>
40 #include <dirent.h>
41 #include <errno.h>
42 #include <string.h>
43 #include <pthread.h>
44 #include "un-namespace.h"
45 
46 #include "libc_private.h"
47 #include "gen-private.h"
48 #include "telldir.h"
49 
50 /*
51  * get next entry in a directory.
52  */
53 struct dirent *
54 _readdir_unlocked(DIR *dirp, int flags)
55 {
56 	struct dirent *dp;
57 	long initial_seek;
58 	long initial_loc = 0;
59 
60 	for (;;) {
61 		if (dirp->dd_loc >= dirp->dd_size) {
62 			if (dirp->dd_flags & __DTF_READALL)
63 				return (NULL);
64 			initial_loc = dirp->dd_loc;
65 			dirp->dd_flags &= ~__DTF_SKIPREAD;
66 			dirp->dd_loc = 0;
67 		}
68 		if (dirp->dd_loc == 0 &&
69 		    !(dirp->dd_flags & (__DTF_READALL | __DTF_SKIPREAD))) {
70 			initial_seek = dirp->dd_seek;
71 			dirp->dd_size = _getdirentries(dirp->dd_fd,
72 			    dirp->dd_buf, dirp->dd_len, &dirp->dd_seek);
73 			if (dirp->dd_size <= 0)
74 				return (NULL);
75 			_fixtelldir(dirp, initial_seek, initial_loc);
76 		}
77 		dirp->dd_flags &= ~__DTF_SKIPREAD;
78 		dp = (struct dirent *)(dirp->dd_buf + dirp->dd_loc);
79 		if ((long)dp & 03L)	/* bogus pointer check */
80 			return (NULL);
81 		if (dp->d_reclen <= 0 ||
82 		    dp->d_reclen > dirp->dd_len + 1 - dirp->dd_loc)
83 			return (NULL);
84 		dirp->dd_loc += dp->d_reclen;
85 		if (dp->d_ino == 0 && (flags & RDU_SKIP) != 0)
86 			continue;
87 		if (dp->d_type == DT_WHT && (dirp->dd_flags & DTF_HIDEW))
88 			continue;
89 		if (dp->d_namlen >= sizeof(dp->d_name) &&
90 		    (flags & RDU_SHORT) != 0)
91 			continue;
92 		return (dp);
93 	}
94 }
95 
96 struct dirent *
97 readdir(DIR *dirp)
98 {
99 	struct dirent *dp;
100 
101 	if (__isthreaded)
102 		_pthread_mutex_lock(&dirp->dd_lock);
103 	dp = _readdir_unlocked(dirp, RDU_SKIP);
104 	if (__isthreaded)
105 		_pthread_mutex_unlock(&dirp->dd_lock);
106 	return (dp);
107 }
108 
109 int
110 __readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result)
111 {
112 	struct dirent *dp;
113 	int saved_errno;
114 
115 	saved_errno = errno;
116 	errno = 0;
117 	if (__isthreaded)
118 		_pthread_mutex_lock(&dirp->dd_lock);
119 	dp = _readdir_unlocked(dirp, RDU_SKIP | RDU_SHORT);
120 	if (dp != NULL)
121 		memcpy(entry, dp, _GENERIC_DIRSIZ(dp));
122 	if (__isthreaded)
123 		_pthread_mutex_unlock(&dirp->dd_lock);
124 
125 	if (errno != 0) {
126 		if (dp == NULL)
127 			return (errno);
128 	} else
129 		errno = saved_errno;
130 
131 	if (dp != NULL)
132 		*result = entry;
133 	else
134 		*result = NULL;
135 
136 	return (0);
137 }
138 
139 __strong_reference(__readdir_r, readdir_r);
140