1 /* Copyright (C) 1991-1996,98,2000-2003,2005,2007
2 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
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.
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
13 Lesser General Public License for more details.
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
26 #include <sys/types.h>
32 #include <dirstream.h>
33 #include <not-cancel.h>
34 #include <kernel-features.h>
37 /* opendir() must not accidentally open something other than a directory.
38 Some OS's have kernel support for that, some don't. In the worst
39 case we have to stat() before the open() AND fstat() after.
41 We have to test at runtime for kernel support since libc may have
42 been compiled with different headers to the kernel it's running on.
43 This test can't be done reliably in the general case. We'll use
44 /dev/null, which if it's not a device lots of stuff will break, as
45 a guinea pig. It may be missing in chroot environments, so we
46 make sure to fail safe. */
48 # ifdef O_DIRECTORY_WORKS
49 # define o_directory_works 1
50 # define tryopen_o_directory() while (1) /* This must not be called. */
52 static int o_directory_works
;
55 tryopen_o_directory (void)
58 int x
= open_not_cancel_2 ("/dev/null", O_RDONLY
|O_NDELAY
|O_DIRECTORY
);
62 close_not_cancel_no_status (x
);
63 o_directory_works
= -1;
65 else if (errno
!= ENOTDIR
)
66 o_directory_works
= -1;
68 o_directory_works
= 1;
73 # define EXTRA_FLAGS O_DIRECTORY
75 # define EXTRA_FLAGS 0
79 /* Open a directory stream on NAME. */
81 __opendir (const char *name
)
83 struct stat64 statbuf
;
85 if (__builtin_expect (name
[0], '\1') == '\0')
87 /* POSIX.1-1990 says an empty name gets ENOENT;
88 but `open' might like it fine. */
94 /* Test whether O_DIRECTORY works. */
95 if (o_directory_works
== 0)
96 tryopen_o_directory ();
98 /* We can skip the expensive `stat' call if O_DIRECTORY works. */
99 if (o_directory_works
< 0)
102 /* We first have to check whether the name is for a directory. We
103 cannot do this after the open() call since the open/close operation
104 performed on, say, a tape device might have undesirable effects. */
105 if (__builtin_expect (__xstat64 (_STAT_VER
, name
, &statbuf
), 0) < 0)
107 if (__builtin_expect (! S_ISDIR (statbuf
.st_mode
), 0))
109 __set_errno (ENOTDIR
);
114 int flags
= O_RDONLY
|O_NDELAY
|EXTRA_FLAGS
|O_LARGEFILE
;
118 int fd
= open_not_cancel_2 (name
, flags
);
119 if (__builtin_expect (fd
, 0) < 0)
122 /* Now make sure this really is a directory and nothing changed since
123 the `stat' call. We do not have to perform the test for the
124 descriptor being associated with a directory if we know the
125 O_DIRECTORY flag is honored by the kernel. */
126 if (__builtin_expect (__fxstat64 (_STAT_VER
, fd
, &statbuf
), 0) < 0)
129 if (o_directory_works
<= 0)
132 if (__builtin_expect (! S_ISDIR (statbuf
.st_mode
), 0))
134 __set_errno (ENOTDIR
);
136 close_not_cancel_no_status (fd
);
141 return __alloc_dir (fd
, true, &statbuf
);
143 weak_alias (__opendir
, opendir
)
146 #ifdef __ASSUME_O_CLOEXEC
147 # define check_have_o_cloexec(fd) 1
150 check_have_o_cloexec (int fd
)
152 if (__have_o_cloexec
== 0)
153 __have_o_cloexec
= (__fcntl (fd
, F_GETFD
, 0) & FD_CLOEXEC
) == 0 ? -1 : 1;
154 return __have_o_cloexec
> 0;
161 __alloc_dir (int fd
, bool close_fd
, const struct stat64
*statp
)
163 /* We always have to set the close-on-exit flag if the user provided
164 the file descriptor. Otherwise only if we have no working
165 O_CLOEXEC support. */
167 if (! close_fd
|| ! check_have_o_cloexec (fd
))
170 if (__builtin_expect (__fcntl (fd
, F_SETFD
, FD_CLOEXEC
), 0) < 0)
174 const size_t default_allocation
= (BUFSIZ
< sizeof (struct dirent64
)
175 ? sizeof (struct dirent64
) : BUFSIZ
);
177 #ifdef _STATBUF_ST_BLKSIZE
178 if (__builtin_expect ((size_t) statp
->st_blksize
>= sizeof (struct dirent64
),
180 allocation
= statp
->st_blksize
;
183 allocation
= default_allocation
;
185 DIR *dirp
= (DIR *) malloc (sizeof (DIR) + allocation
);
188 #ifdef _STATBUF_ST_BLKSIZE
189 if (allocation
== statp
->st_blksize
190 && allocation
!= default_allocation
)
192 allocation
= default_allocation
;
193 dirp
= (DIR *) malloc (sizeof (DIR) + allocation
);
201 int save_errno
= errno
;
202 close_not_cancel_no_status (fd
);
203 __set_errno (save_errno
);
211 __libc_lock_init (dirp
->lock
);
213 dirp
->allocation
= allocation
;