153 lines
4.1 KiB
C
153 lines
4.1 KiB
C
/* Copyright (C) 1991, 92, 93, 94, 95, 96, 98 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include <errno.h>
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#include <limits.h>
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#include <stddef.h>
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#include <stdlib.h>
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#include <dirent.h>
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#include <fcntl.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <dirstream.h>
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/* opendir() must not accidentally open something other than a directory.
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Some OS's have kernel support for that, some don't. In the worst
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case we have to stat() before the open() AND fstat() after.
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We have to test at runtime for kernel support since libc may have
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been compiled with different headers to the kernel it's running on.
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This test can't be done reliably in the general case. We'll use
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/dev/null, which if it's not a device lots of stuff will break, as
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a guinea pig. It may be missing in chroot environments, so we
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make sure to fail safe. */
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#ifdef O_DIRECTORY
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static int o_directory_works = -1;
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static void
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tryopen_o_directory (void)
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{
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int serrno = errno;
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int x = __open ("/dev/null", O_RDONLY|O_NDELAY|O_DIRECTORY);
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if (x >= 0)
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{
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__close (x);
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o_directory_works = 0;
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}
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else if (errno != ENOTDIR)
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o_directory_works = 0;
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else
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o_directory_works = 1;
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__set_errno (serrno);
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}
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# define EXTRA_FLAGS O_DIRECTORY
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#else
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# define EXTRA_FLAGS 0
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#endif
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/* Open a directory stream on NAME. */
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DIR *
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__opendir (const char *name)
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{
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DIR *dirp;
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struct stat statbuf;
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int fd;
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size_t allocation;
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int save_errno;
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if (name[0] == '\0')
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{
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/* POSIX.1-1990 says an empty name gets ENOENT;
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but `open' might like it fine. */
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__set_errno (ENOENT);
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return NULL;
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}
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#ifdef O_DIRECTORY
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/* Test whether O_DIRECTORY works. */
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if (o_directory_works == -1)
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tryopen_o_directory ();
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/* We can skip the expensive `stat' call if O_DIRECTORY works. */
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if (o_directory_works == 0)
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#endif
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{
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/* We first have to check whether the name is for a directory. We
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cannot do this after the open() call since the open/close operation
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performed on, say, a tape device might have undesirable effects. */
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if (__stat (name, &statbuf) < 0)
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return NULL;
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if (! S_ISDIR (statbuf.st_mode))
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{
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__set_errno (ENOTDIR);
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return NULL;
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}
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}
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fd = __open (name, O_RDONLY|O_NDELAY|EXTRA_FLAGS);
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if (fd < 0)
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return NULL;
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/* Now make sure this really is a directory and nothing changed since
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the `stat' call. */
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if (__fstat (fd, &statbuf) < 0)
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goto lose;
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if (! S_ISDIR (statbuf.st_mode))
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{
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save_errno = ENOTDIR;
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goto lose;
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}
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if (__fcntl (fd, F_SETFD, FD_CLOEXEC) < 0)
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goto lose;
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#ifdef _STATBUF_ST_BLKSIZE
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if (statbuf.st_blksize < sizeof (struct dirent))
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allocation = sizeof (struct dirent);
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else
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allocation = statbuf.st_blksize;
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#else
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allocation = (BUFSIZ < sizeof (struct dirent)
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? sizeof (struct dirent) : BUFSIZ);
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#endif
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dirp = (DIR *) calloc (1, sizeof (DIR) + allocation); /* Zero-fill. */
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if (dirp == NULL)
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lose:
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{
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save_errno = errno;
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(void) __close (fd);
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__set_errno (save_errno);
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return NULL;
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}
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dirp->data = (char *) (dirp + 1);
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dirp->allocation = allocation;
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dirp->fd = fd;
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__libc_lock_init (dirp->lock);
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return dirp;
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}
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weak_alias (__opendir, opendir)
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