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28377d1b | 1 | /* Copyright (C) 1991-1996,98,2000-2003,2005,2007,2009,2011 |
858ee15d | 2 | Free Software Foundation, Inc. |
01c901a5 UD |
3 | This file is part of the GNU C Library. |
4 | ||
5 | The GNU C Library is free software; you can redistribute it and/or | |
41bdb6e2 AJ |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either | |
8 | version 2.1 of the License, or (at your option) any later version. | |
01c901a5 UD |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
41bdb6e2 | 13 | Lesser General Public License for more details. |
01c901a5 | 14 | |
41bdb6e2 AJ |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, write to the Free | |
17 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
18 | 02111-1307 USA. */ | |
28f540f4 | 19 | |
c55fbd1e | 20 | #include <assert.h> |
28f540f4 RM |
21 | #include <errno.h> |
22 | #include <limits.h> | |
23 | #include <stddef.h> | |
24 | #include <stdlib.h> | |
25 | #include <dirent.h> | |
26 | #include <fcntl.h> | |
27 | #include <sys/types.h> | |
28 | #include <sys/stat.h> | |
29 | #include <unistd.h> | |
30 | #include <stdio.h> | |
39358e8b | 31 | #include <string.h> |
28f540f4 | 32 | |
92777700 | 33 | #include <dirstream.h> |
73299943 | 34 | #include <not-cancel.h> |
cbf0489b | 35 | #include <kernel-features.h> |
73299943 | 36 | |
28f540f4 | 37 | |
8b7fb588 UD |
38 | /* opendir() must not accidentally open something other than a directory. |
39 | Some OS's have kernel support for that, some don't. In the worst | |
40 | case we have to stat() before the open() AND fstat() after. | |
41 | ||
42 | We have to test at runtime for kernel support since libc may have | |
43 | been compiled with different headers to the kernel it's running on. | |
44 | This test can't be done reliably in the general case. We'll use | |
45 | /dev/null, which if it's not a device lots of stuff will break, as | |
46 | a guinea pig. It may be missing in chroot environments, so we | |
47 | make sure to fail safe. */ | |
413bb8ca | 48 | #ifdef O_DIRECTORY |
675e4015 UD |
49 | # ifdef O_DIRECTORY_WORKS |
50 | # define o_directory_works 1 | |
51 | # define tryopen_o_directory() while (1) /* This must not be called. */ | |
52 | # else | |
8b7fb588 | 53 | static int o_directory_works; |
413bb8ca UD |
54 | |
55 | static void | |
8b7fb588 UD |
56 | tryopen_o_directory (void) |
57 | { | |
58 | int serrno = errno; | |
73299943 | 59 | int x = open_not_cancel_2 ("/dev/null", O_RDONLY|O_NDELAY|O_DIRECTORY); |
8b7fb588 UD |
60 | |
61 | if (x >= 0) | |
62 | { | |
73299943 | 63 | close_not_cancel_no_status (x); |
8b7fb588 UD |
64 | o_directory_works = -1; |
65 | } | |
66 | else if (errno != ENOTDIR) | |
67 | o_directory_works = -1; | |
68 | else | |
69 | o_directory_works = 1; | |
70 | ||
71 | __set_errno (serrno); | |
72 | } | |
675e4015 | 73 | # endif |
413bb8ca UD |
74 | # define EXTRA_FLAGS O_DIRECTORY |
75 | #else | |
76 | # define EXTRA_FLAGS 0 | |
9ffbb612 UD |
77 | #endif |
78 | ||
79 | ||
28f540f4 | 80 | DIR * |
c55fbd1e UD |
81 | internal_function |
82 | __opendirat (int dfd, const char *name) | |
28f540f4 | 83 | { |
8edf6e0d | 84 | struct stat64 statbuf; |
62f63c47 | 85 | struct stat64 *statp = NULL; |
28f540f4 | 86 | |
726b7b0f | 87 | if (__builtin_expect (name[0], '\1') == '\0') |
28f540f4 RM |
88 | { |
89 | /* POSIX.1-1990 says an empty name gets ENOENT; | |
90 | but `open' might like it fine. */ | |
c4029823 | 91 | __set_errno (ENOENT); |
28f540f4 RM |
92 | return NULL; |
93 | } | |
94 | ||
413bb8ca UD |
95 | #ifdef O_DIRECTORY |
96 | /* Test whether O_DIRECTORY works. */ | |
8b7fb588 | 97 | if (o_directory_works == 0) |
413bb8ca UD |
98 | tryopen_o_directory (); |
99 | ||
100 | /* We can skip the expensive `stat' call if O_DIRECTORY works. */ | |
8b7fb588 | 101 | if (o_directory_works < 0) |
413bb8ca | 102 | #endif |
99e46354 | 103 | { |
413bb8ca UD |
104 | /* We first have to check whether the name is for a directory. We |
105 | cannot do this after the open() call since the open/close operation | |
106 | performed on, say, a tape device might have undesirable effects. */ | |
726b7b0f | 107 | if (__builtin_expect (__xstat64 (_STAT_VER, name, &statbuf), 0) < 0) |
413bb8ca | 108 | return NULL; |
726b7b0f | 109 | if (__builtin_expect (! S_ISDIR (statbuf.st_mode), 0)) |
413bb8ca UD |
110 | { |
111 | __set_errno (ENOTDIR); | |
112 | return NULL; | |
113 | } | |
99e46354 UD |
114 | } |
115 | ||
cbf0489b UD |
116 | int flags = O_RDONLY|O_NDELAY|EXTRA_FLAGS|O_LARGEFILE; |
117 | #ifdef O_CLOEXEC | |
118 | flags |= O_CLOEXEC; | |
119 | #endif | |
c55fbd1e UD |
120 | int fd; |
121 | #ifdef IS_IN_rtld | |
122 | assert (dfd == AT_FDCWD); | |
123 | fd = open_not_cancel_2 (name, flags); | |
124 | #else | |
125 | fd = openat_not_cancel_3 (dfd, name, flags); | |
126 | #endif | |
726b7b0f | 127 | if (__builtin_expect (fd, 0) < 0) |
4bd8be48 UD |
128 | return NULL; |
129 | ||
256ba888 UD |
130 | #ifdef O_DIRECTORY |
131 | if (o_directory_works <= 0) | |
132 | #endif | |
4bd8be48 | 133 | { |
62f63c47 UD |
134 | /* Now make sure this really is a directory and nothing changed since |
135 | the `stat' call. */ | |
136 | if (__builtin_expect (__fxstat64 (_STAT_VER, fd, &statbuf), 0) < 0) | |
137 | goto lose; | |
256ba888 UD |
138 | if (__builtin_expect (! S_ISDIR (statbuf.st_mode), 0)) |
139 | { | |
1812d50b UD |
140 | __set_errno (ENOTDIR); |
141 | lose: | |
142 | close_not_cancel_no_status (fd); | |
143 | return NULL; | |
256ba888 | 144 | } |
62f63c47 | 145 | statp = &statbuf; |
4bd8be48 | 146 | } |
28f540f4 | 147 | |
28377d1b | 148 | return __alloc_dir (fd, true, 0, statp); |
1812d50b | 149 | } |
c55fbd1e UD |
150 | |
151 | ||
152 | /* Open a directory stream on NAME. */ | |
153 | DIR * | |
154 | __opendir (const char *name) | |
155 | { | |
156 | return __opendirat (AT_FDCWD, name); | |
157 | } | |
1812d50b UD |
158 | weak_alias (__opendir, opendir) |
159 | ||
160 | ||
cbf0489b UD |
161 | #ifdef __ASSUME_O_CLOEXEC |
162 | # define check_have_o_cloexec(fd) 1 | |
163 | #else | |
164 | static int | |
165 | check_have_o_cloexec (int fd) | |
166 | { | |
167 | if (__have_o_cloexec == 0) | |
168 | __have_o_cloexec = (__fcntl (fd, F_GETFD, 0) & FD_CLOEXEC) == 0 ? -1 : 1; | |
169 | return __have_o_cloexec > 0; | |
170 | } | |
171 | #endif | |
172 | ||
173 | ||
1812d50b UD |
174 | DIR * |
175 | internal_function | |
28377d1b | 176 | __alloc_dir (int fd, bool close_fd, int flags, const struct stat64 *statp) |
1812d50b | 177 | { |
cbf0489b UD |
178 | /* We always have to set the close-on-exit flag if the user provided |
179 | the file descriptor. Otherwise only if we have no working | |
180 | O_CLOEXEC support. */ | |
181 | #ifdef O_CLOEXEC | |
28377d1b UD |
182 | if ((! close_fd && (flags & O_CLOEXEC) == 0) |
183 | || ! check_have_o_cloexec (fd)) | |
cbf0489b UD |
184 | #endif |
185 | { | |
186 | if (__builtin_expect (__fcntl (fd, F_SETFD, FD_CLOEXEC), 0) < 0) | |
187 | goto lose; | |
188 | } | |
28f540f4 | 189 | |
62f63c47 UD |
190 | const size_t default_allocation = (4 * BUFSIZ < sizeof (struct dirent64) |
191 | ? sizeof (struct dirent64) : 4 * BUFSIZ); | |
192 | const size_t small_allocation = (BUFSIZ < sizeof (struct dirent64) | |
193 | ? sizeof (struct dirent64) : BUFSIZ); | |
194 | size_t allocation = default_allocation; | |
28f540f4 | 195 | #ifdef _STATBUF_ST_BLKSIZE |
62f63c47 | 196 | if (statp != NULL && default_allocation < statp->st_blksize) |
1812d50b | 197 | allocation = statp->st_blksize; |
28f540f4 | 198 | #endif |
9eecb5e8 | 199 | |
fa39685d | 200 | DIR *dirp = (DIR *) malloc (sizeof (DIR) + allocation); |
9eecb5e8 | 201 | if (dirp == NULL) |
28f540f4 | 202 | { |
62f63c47 UD |
203 | allocation = small_allocation; |
204 | dirp = (DIR *) malloc (sizeof (DIR) + allocation); | |
205 | ||
221e5230 | 206 | if (dirp == NULL) |
221e5230 UD |
207 | lose: |
208 | { | |
209 | if (close_fd) | |
210 | { | |
211 | int save_errno = errno; | |
212 | close_not_cancel_no_status (fd); | |
213 | __set_errno (save_errno); | |
214 | } | |
215 | return NULL; | |
18b8e054 | 216 | } |
28f540f4 | 217 | } |
c1509239 | 218 | |
c8ccd8e3 | 219 | dirp->fd = fd; |
858ee15d | 220 | #ifndef NOT_IN_libc |
0d204b0a | 221 | __libc_lock_init (dirp->lock); |
858ee15d | 222 | #endif |
c8ccd8e3 | 223 | dirp->allocation = allocation; |
fa39685d UD |
224 | dirp->size = 0; |
225 | dirp->offset = 0; | |
226 | dirp->filepos = 0; | |
c1509239 | 227 | |
28f540f4 RM |
228 | return dirp; |
229 | } |