Assume O_DIRECTORY for opendir

This patch assumes O_DIRECTORY works as defined by POSIX on opendir
implementation (aligning with other glibc code, for instance pwd).  This
allows remove both the fallback code to handle system with missing or
broken O_DIRECTORY along with the Linux specific opendir.c which just
advertise the working flag.

Checked on aarch64-linux-gnu, x86_64-linux-gnu, i686-linux-gnu,
sparcv9-linux-gnu, sparc64-linux-gnu, powerpc-linux-gnu, and
powerpc64le-linux-gnu.

	* sysdeps/posix/opendir.c (o_directory_works, tryopen_o_directory):
	Remove definitions.
	(opendir_oflags): Use O_DIRECTORY regardless.
	(__opendir, __opendirat): Remove need_isdir_precheck usage.
	* sysdeps/unix/sysv/linux/opendir.c: Remove file.
This commit is contained in:
Adhemerval Zanella 2018-03-01 15:55:25 -03:00
parent 57408435ad
commit 8e4754ed7e
3 changed files with 12 additions and 122 deletions

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@ -1,3 +1,11 @@
2018-04-03 Adhemerval Zanella <adhemerval.zanella@linaro.org>
* sysdeps/posix/opendir.c (o_directory_works, tryopen_o_directory):
Remove definitions.
(opendir_oflags): Use O_DIRECTORY regardless.
(__opendir, __opendirat): Remove need_isdir_precheck usage.
* sysdeps/unix/sysv/linux/opendir.c: Remove file.
2018-04-02 Samuel Thibault <samuel.thibault@ens-lyon.org>
* sysdeps/mach/hurd/bits/local_lim.h (_POSIX_THREAD_KEYS_MAX,

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@ -15,24 +15,13 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <assert.h>
#include <errno.h>
#include <limits.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdlib.h>
#include <dirent.h>
#include <fcntl.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <stdio.h> /* For BUFSIZ. */
#include <sys/param.h> /* For MIN and MAX. */
#include <dirstream.h>
#include <not-cancel.h>
#include <kernel-features.h>
/* The st_blksize value of the directory is used as a hint for the
size of the buffer which receives struct dirent values from the
@ -40,49 +29,8 @@
file system provides a bogus value. */
#define MAX_DIR_BUFFER_SIZE 1048576U
/* opendir() must not accidentally open something other than a directory.
Some OS's have kernel support for that, some don't. In the worst
case we have to stat() before the open() AND fstat() after.
We have to test at runtime for kernel support since libc may have
been compiled with different headers to the kernel it's running on.
This test can't be done reliably in the general case. We'll use
/dev/null, which if it's not a device lots of stuff will break, as
a guinea pig. It may be missing in chroot environments, so we
make sure to fail safe. */
#ifdef O_DIRECTORY
# ifdef O_DIRECTORY_WORKS
# define o_directory_works 1
# define tryopen_o_directory() while (1) /* This must not be called. */
# else
static int o_directory_works;
static void
tryopen_o_directory (void)
{
int serrno = errno;
int x = __open_nocancel ("/dev/null", O_RDONLY|O_NDELAY|O_DIRECTORY);
if (x >= 0)
{
__close_nocancel_nostatus (x);
o_directory_works = -1;
}
else if (errno != ENOTDIR)
o_directory_works = -1;
else
o_directory_works = 1;
__set_errno (serrno);
}
# endif
# define EXTRA_FLAGS O_DIRECTORY
#else
# define EXTRA_FLAGS 0
#endif
enum {
opendir_oflags = O_RDONLY|O_NDELAY|EXTRA_FLAGS|O_LARGEFILE|O_CLOEXEC
opendir_oflags = O_RDONLY|O_NDELAY|O_DIRECTORY|O_LARGEFILE|O_CLOEXEC
};
static bool
@ -98,21 +46,6 @@ invalid_name (const char *name)
return false;
}
static bool
need_isdir_precheck (void)
{
#ifdef O_DIRECTORY
/* Test whether O_DIRECTORY works. */
if (o_directory_works == 0)
tryopen_o_directory ();
/* We can skip the expensive `stat' call if O_DIRECTORY works. */
return o_directory_works < 0;
#endif
return true;
}
static DIR *
opendir_tail (int fd)
{
@ -144,22 +77,6 @@ __opendirat (int dfd, const char *name)
if (__glibc_unlikely (invalid_name (name)))
return NULL;
if (need_isdir_precheck ())
{
/* We first have to check whether the name is for a directory. We
cannot do this after the open() call since the open/close operation
performed on, say, a tape device might have undesirable effects. */
struct stat64 statbuf;
if (__glibc_unlikely (__fxstatat64 (_STAT_VER, dfd, name,
&statbuf, 0) < 0))
return NULL;
if (__glibc_unlikely (! S_ISDIR (statbuf.st_mode)))
{
__set_errno (ENOTDIR);
return NULL;
}
}
return opendir_tail (__openat_nocancel (dfd, name, opendir_oflags));
}
#endif
@ -172,21 +89,6 @@ __opendir (const char *name)
if (__glibc_unlikely (invalid_name (name)))
return NULL;
if (need_isdir_precheck ())
{
/* We first have to check whether the name is for a directory. We
cannot do this after the open() call since the open/close operation
performed on, say, a tape device might have undesirable effects. */
struct stat64 statbuf;
if (__glibc_unlikely (__xstat64 (_STAT_VER, name, &statbuf) < 0))
return NULL;
if (__glibc_unlikely (! S_ISDIR (statbuf.st_mode)))
{
__set_errno (ENOTDIR);
return NULL;
}
}
return opendir_tail (__open_nocancel (name, opendir_oflags));
}
weak_alias (__opendir, opendir)

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@ -1,20 +0,0 @@
/* Copyright (C) 2000-2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#define O_DIRECTORY_WORKS 1
#include <sysdeps/posix/opendir.c>