1 /* $NetBSD: readdir.c,v 1.27 2024/09/10 17:11:19 riastradh Exp $ */
2
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 <sys/cdefs.h>
33 #if defined(LIBC_SCCS) && !defined(lint)
34 #if 0
35 static char sccsid[] = "@(#)readdir.c 8.3 (Berkeley) 9/29/94";
36 #else
37 __RCSID("$NetBSD: readdir.c,v 1.27 2024/09/10 17:11:19 riastradh Exp $");
38 #endif
39 #endif /* LIBC_SCCS and not lint */
40
41 #include "namespace.h"
42 #include "reentrant.h"
43 #include "extern.h"
44 #include <sys/param.h>
45
46 #include <dirent.h>
47 #include <errno.h>
48 #include <string.h>
49 #include <unistd.h>
50
51 #include "dirent_private.h"
52
53 /*
54 * get next entry in a directory.
55 */
56 struct dirent *
_readdir_unlocked(DIR * dirp,int skipdeleted)57 _readdir_unlocked(DIR *dirp, int skipdeleted)
58 {
59 const int saved_errno = errno;
60 struct dirent *dp;
61
62 for (;;) {
63 if (dirp->dd_loc >= dirp->dd_size) {
64 if (dirp->dd_flags & __DTF_READALL)
65 break;
66 dirp->dd_loc = 0;
67 }
68 if (dirp->dd_loc == 0 && !(dirp->dd_flags & __DTF_READALL)) {
69 dirp->dd_seek = lseek(dirp->dd_fd, (off_t)0, SEEK_CUR);
70 dirp->dd_size = getdents(dirp->dd_fd,
71 dirp->dd_buf, (size_t)dirp->dd_len);
72 if (dirp->dd_size == 0) /* end of directory */
73 break;
74 if (dirp->dd_size == -1) /* getdents sets errno */
75 return NULL;
76 if (dirp->dd_size < 0) { /* paranoia */
77 errno = EIO;
78 return NULL;
79 }
80 }
81 dp = (struct dirent *)
82 (void *)(dirp->dd_buf + (size_t)dirp->dd_loc);
83 /* bogus pointer check */
84 if ((intptr_t)dp & _DIRENT_ALIGN(dp)) {
85 errno = EIO;
86 return NULL;
87 }
88 /* d_reclen is unsigned; no need to compare it <= 0 */
89 if (dp->d_reclen > dirp->dd_len + 1 - dirp->dd_loc) {
90 errno = EIO;
91 return NULL;
92 }
93 dirp->dd_loc += dp->d_reclen;
94 if (dp->d_ino == 0 && skipdeleted)
95 continue;
96 if (dp->d_type == DT_WHT && (dirp->dd_flags & DTF_HIDEW))
97 continue;
98 return dp;
99 }
100
101 errno = saved_errno;
102 return NULL;
103 }
104
105 struct dirent *
readdir(DIR * dirp)106 readdir(DIR *dirp)
107 {
108 struct dirent *dp;
109
110 #ifdef _REENTRANT
111 if (__isthreaded) {
112 mutex_lock((mutex_t *)dirp->dd_lock);
113 dp = _readdir_unlocked(dirp, 1);
114 mutex_unlock((mutex_t *)dirp->dd_lock);
115 }
116 else
117 #endif
118 dp = _readdir_unlocked(dirp, 1);
119 return (dp);
120 }
121
122 int
readdir_r(DIR * dirp,struct dirent * entry,struct dirent ** result)123 readdir_r(DIR *dirp, struct dirent *entry, struct dirent **result)
124 {
125 struct dirent *dp;
126 int saved_errno;
127
128 saved_errno = errno;
129 errno = 0;
130 #ifdef _REENTRANT
131 if (__isthreaded) {
132 mutex_lock((mutex_t *)dirp->dd_lock);
133 if ((dp = _readdir_unlocked(dirp, 1)) != NULL)
134 memcpy(entry, dp, (size_t)_DIRENT_SIZE(dp));
135 mutex_unlock((mutex_t *)dirp->dd_lock);
136 }
137 else
138 #endif
139 if ((dp = _readdir_unlocked(dirp, 1)) != NULL)
140 memcpy(entry, dp, (size_t)_DIRENT_SIZE(dp));
141
142 if (errno != 0) {
143 if (dp == NULL)
144 return (errno);
145 } else
146 errno = saved_errno;
147
148 if (dp != NULL)
149 *result = entry;
150 else
151 *result = NULL;
152
153 return (0);
154 }
155