xref: /freebsd/lib/libc/gen/readdir.c (revision c9dbb1cc52b063bbd9ab078a7afc89a8696da659)
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  * 4. Neither the name of the University nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #if defined(LIBC_SCCS) && !defined(lint)
31 static char sccsid[] = "@(#)readdir.c	8.3 (Berkeley) 9/29/94";
32 #endif /* LIBC_SCCS and not lint */
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
35 
36 #include "namespace.h"
37 #include <sys/param.h>
38 #include <dirent.h>
39 #include <errno.h>
40 #include <string.h>
41 #include <pthread.h>
42 #include "un-namespace.h"
43 
44 #include "libc_private.h"
45 #include "gen-private.h"
46 #include "telldir.h"
47 
48 /*
49  * get next entry in a directory.
50  */
51 struct dirent *
52 _readdir_unlocked(DIR *dirp, int skip)
53 {
54 	struct dirent *dp;
55 	long initial_seek;
56 	long initial_loc = 0;
57 
58 	for (;;) {
59 		if (dirp->dd_loc >= dirp->dd_size) {
60 			if (dirp->dd_flags & __DTF_READALL)
61 				return (NULL);
62 			initial_loc = dirp->dd_loc;
63 			dirp->dd_flags &= ~__DTF_SKIPREAD;
64 			dirp->dd_loc = 0;
65 		}
66 		if (dirp->dd_loc == 0 &&
67 		    !(dirp->dd_flags & (__DTF_READALL | __DTF_SKIPREAD))) {
68 			initial_seek = dirp->dd_seek;
69 			dirp->dd_size = _getdirentries(dirp->dd_fd,
70 			    dirp->dd_buf, dirp->dd_len, &dirp->dd_seek);
71 			if (dirp->dd_size <= 0)
72 				return (NULL);
73 			_fixtelldir(dirp, initial_seek, initial_loc);
74 		}
75 		dirp->dd_flags &= ~__DTF_SKIPREAD;
76 		dp = (struct dirent *)(dirp->dd_buf + dirp->dd_loc);
77 		if ((long)dp & 03L)	/* bogus pointer check */
78 			return (NULL);
79 		if (dp->d_reclen <= 0 ||
80 		    dp->d_reclen > dirp->dd_len + 1 - dirp->dd_loc)
81 			return (NULL);
82 		dirp->dd_loc += dp->d_reclen;
83 		if (dp->d_ino == 0 && skip)
84 			continue;
85 		if (dp->d_type == DT_WHT && (dirp->dd_flags & DTF_HIDEW))
86 			continue;
87 		return (dp);
88 	}
89 }
90 
91 struct dirent *
92 readdir(DIR *dirp)
93 {
94 	struct dirent	*dp;
95 
96 	if (__isthreaded) {
97 		_pthread_mutex_lock(&dirp->dd_lock);
98 		dp = _readdir_unlocked(dirp, 1);
99 		_pthread_mutex_unlock(&dirp->dd_lock);
100 	}
101 	else
102 		dp = _readdir_unlocked(dirp, 1);
103 	return (dp);
104 }
105 
106 int
107 readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result)
108 {
109 	struct dirent *dp;
110 	int saved_errno;
111 
112 	saved_errno = errno;
113 	errno = 0;
114 	if (__isthreaded) {
115 		_pthread_mutex_lock(&dirp->dd_lock);
116 		if ((dp = _readdir_unlocked(dirp, 1)) != NULL)
117 			memcpy(entry, dp, _GENERIC_DIRSIZ(dp));
118 		_pthread_mutex_unlock(&dirp->dd_lock);
119 	}
120 	else if ((dp = _readdir_unlocked(dirp, 1)) != NULL)
121 		memcpy(entry, dp, _GENERIC_DIRSIZ(dp));
122 
123 	if (errno != 0) {
124 		if (dp == NULL)
125 			return (errno);
126 	} else
127 		errno = saved_errno;
128 
129 	if (dp != NULL)
130 		*result = entry;
131 	else
132 		*result = NULL;
133 
134 	return (0);
135 }
136