1 /* Copyright (C) 1991-1996,98,2000-2002, 2003 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, write to the Free
16 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
25 #include <sys/types.h>
31 #include <dirstream.h>
32 #include <not-cancel.h>
35 /* opendir() must not accidentally open something other than a directory.
36 Some OS's have kernel support for that, some don't. In the worst
37 case we have to stat() before the open() AND fstat() after.
39 We have to test at runtime for kernel support since libc may have
40 been compiled with different headers to the kernel it's running on.
41 This test can't be done reliably in the general case. We'll use
42 /dev/null, which if it's not a device lots of stuff will break, as
43 a guinea pig. It may be missing in chroot environments, so we
44 make sure to fail safe. */
46 # ifdef O_DIRECTORY_WORKS
47 # define o_directory_works 1
48 # define tryopen_o_directory() while (1) /* This must not be called. */
50 static int o_directory_works
;
53 tryopen_o_directory (void)
56 int x
= open_not_cancel_2 ("/dev/null", O_RDONLY
|O_NDELAY
|O_DIRECTORY
);
60 close_not_cancel_no_status (x
);
61 o_directory_works
= -1;
63 else if (errno
!= ENOTDIR
)
64 o_directory_works
= -1;
66 o_directory_works
= 1;
71 # define EXTRA_FLAGS O_DIRECTORY
73 # define EXTRA_FLAGS 0
77 /* Open a directory stream on NAME. */
79 __opendir (const char *name
)
82 struct stat64 statbuf
;
87 if (__builtin_expect (name
[0], '\1') == '\0')
89 /* POSIX.1-1990 says an empty name gets ENOENT;
90 but `open' might like it fine. */
96 /* Test whether O_DIRECTORY works. */
97 if (o_directory_works
== 0)
98 tryopen_o_directory ();
100 /* We can skip the expensive `stat' call if O_DIRECTORY works. */
101 if (o_directory_works
< 0)
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. */
107 if (__builtin_expect (__xstat64 (_STAT_VER
, name
, &statbuf
), 0) < 0)
109 if (__builtin_expect (! S_ISDIR (statbuf
.st_mode
), 0))
111 __set_errno (ENOTDIR
);
116 fd
= open_not_cancel_2 (name
, O_RDONLY
|O_NDELAY
|EXTRA_FLAGS
|O_LARGEFILE
);
117 if (__builtin_expect (fd
, 0) < 0)
120 /* Now make sure this really is a directory and nothing changed since
121 the `stat' call. We do not have to perform the test for the
122 descriptor being associated with a directory if we know the
123 O_DIRECTORY flag is honored by the kernel. */
124 if (__builtin_expect (__fxstat64 (_STAT_VER
, fd
, &statbuf
), 0) < 0)
127 if (o_directory_works
<= 0)
130 if (__builtin_expect (! S_ISDIR (statbuf
.st_mode
), 0))
132 save_errno
= ENOTDIR
;
137 if (__builtin_expect (__fcntl (fd
, F_SETFD
, FD_CLOEXEC
), 0) < 0)
140 #ifdef _STATBUF_ST_BLKSIZE
141 if (__builtin_expect ((size_t) statbuf
.st_blksize
>= sizeof (struct dirent64
),
143 allocation
= statbuf
.st_blksize
;
146 allocation
= (BUFSIZ
< sizeof (struct dirent64
)
147 ? sizeof (struct dirent64
) : BUFSIZ
);
149 const int pad
= -sizeof (DIR) % __alignof__ (struct dirent64
);
151 dirp
= (DIR *) malloc (sizeof (DIR) + allocation
+ pad
);
156 close_not_cancel_no_status (fd
);
157 __set_errno (save_errno
);
160 memset (dirp
, '\0', sizeof (DIR));
161 dirp
->data
= (char *) (dirp
+ 1) + pad
;
162 dirp
->allocation
= allocation
;
165 __libc_lock_init (dirp
->lock
);
169 weak_alias (__opendir
, opendir
)