xref: /freebsd/lib/libc/gen/readdir.c (revision a2f733abcff64628b7771a47089628b7327a88bd)
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 #include "namespace.h"
33 #include <sys/param.h>
34 #include <dirent.h>
35 #include <errno.h>
36 #include <string.h>
37 #include <pthread.h>
38 #include "un-namespace.h"
39 
40 #include "libc_private.h"
41 #include "gen-private.h"
42 #include "telldir.h"
43 
44 /*
45  * get next entry in a directory.
46  */
47 struct dirent *
48 _readdir_unlocked(DIR *dirp, int flags)
49 {
50 	struct dirent *dp;
51 	long initial_seek;
52 	long initial_loc = 0;
53 
54 	for (;;) {
55 		if (dirp->dd_loc >= dirp->dd_size) {
56 			if (dirp->dd_flags & __DTF_READALL)
57 				return (NULL);
58 			initial_loc = dirp->dd_loc;
59 			dirp->dd_flags &= ~__DTF_SKIPREAD;
60 			dirp->dd_loc = 0;
61 		}
62 		if (dirp->dd_loc == 0 &&
63 		    !(dirp->dd_flags & (__DTF_READALL | __DTF_SKIPREAD))) {
64 			initial_seek = dirp->dd_seek;
65 			dirp->dd_size = _getdirentries(dirp->dd_fd,
66 			    dirp->dd_buf, dirp->dd_len, &dirp->dd_seek);
67 			if (dirp->dd_size <= 0)
68 				return (NULL);
69 			_fixtelldir(dirp, initial_seek, initial_loc);
70 		}
71 		dirp->dd_flags &= ~__DTF_SKIPREAD;
72 		dp = (struct dirent *)(dirp->dd_buf + dirp->dd_loc);
73 		if ((long)dp & 03L)	/* bogus pointer check */
74 			return (NULL);
75 		if (dp->d_reclen <= 0 ||
76 		    dp->d_reclen > dirp->dd_len + 1 - dirp->dd_loc)
77 			return (NULL);
78 		dirp->dd_loc += dp->d_reclen;
79 		if (dp->d_ino == 0 && (flags & RDU_SKIP) != 0)
80 			continue;
81 		if (dp->d_type == DT_WHT && (dirp->dd_flags & DTF_HIDEW))
82 			continue;
83 		if (dp->d_namlen >= sizeof(dp->d_name) &&
84 		    (flags & RDU_SHORT) != 0)
85 			continue;
86 		return (dp);
87 	}
88 }
89 
90 struct dirent *
91 readdir(DIR *dirp)
92 {
93 	struct dirent *dp;
94 
95 	if (__isthreaded)
96 		_pthread_mutex_lock(&dirp->dd_lock);
97 	dp = _readdir_unlocked(dirp, RDU_SKIP);
98 	if (__isthreaded)
99 		_pthread_mutex_unlock(&dirp->dd_lock);
100 	return (dp);
101 }
102 
103 int
104 __readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result)
105 {
106 	struct dirent *dp;
107 	int saved_errno;
108 
109 	saved_errno = errno;
110 	errno = 0;
111 	if (__isthreaded)
112 		_pthread_mutex_lock(&dirp->dd_lock);
113 	dp = _readdir_unlocked(dirp, RDU_SKIP | RDU_SHORT);
114 	if (dp != NULL)
115 		memcpy(entry, dp, _GENERIC_DIRSIZ(dp));
116 	if (__isthreaded)
117 		_pthread_mutex_unlock(&dirp->dd_lock);
118 
119 	if (errno != 0) {
120 		if (dp == NULL)
121 			return (errno);
122 	} else
123 		errno = saved_errno;
124 
125 	if (dp != NULL)
126 		*result = entry;
127 	else
128 		*result = NULL;
129 
130 	return (0);
131 }
132 
133 __strong_reference(__readdir_r, readdir_r);
134