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linux: Make fdopendir fail with O_PATH (BZ 30373)

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It is not strictly required by the POSIX, since O_PATH is a Linux
extension, but it is QoI to fail early instead of at readdir.  Also
the check is free, since fdopendir already checks if the file
descriptor is opened for read.

Checked on x86_64-linux-gnu.
This commit is contained in:
Adhemerval Zanella 2023-08-10 08:56:00 -03:00
parent 807849965b
commit 4e16d89866
3 changed files with 56 additions and 1 deletions
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1
sysdeps/unix/sysv/linux/Makefile
View File

@ -201,6 +201,7 @@ tests += \
tst-clone3 \ tst-clone3 \
tst-epoll \ tst-epoll \
tst-fanotify \ tst-fanotify \
tst-fdopendir-o_path \
tst-getauxval \ tst-getauxval \
tst-gettid \ tst-gettid \
tst-gettid-kill \ tst-gettid-kill \

8
sysdeps/unix/sysv/linux/fdopendir.c
View File

@ -37,10 +37,16 @@ __fdopendir (int fd)
return NULL; return NULL;
} }
/* Make sure the descriptor allows for reading. */
int flags = __fcntl64_nocancel (fd, F_GETFL); int flags = __fcntl64_nocancel (fd, F_GETFL);
if (__glibc_unlikely (flags == -1)) if (__glibc_unlikely (flags == -1))
return NULL; return NULL;
/* Fail early for descriptors opened with O_PATH. */
if (__glibc_unlikely (flags & O_PATH))
{
__set_errno (EBADF);
return NULL;
}
/* Make sure the descriptor allows for reading. */
if (__glibc_unlikely ((flags & O_ACCMODE) == O_WRONLY)) if (__glibc_unlikely ((flags & O_ACCMODE) == O_WRONLY))
{ {
__set_errno (EINVAL); __set_errno (EINVAL);

48
sysdeps/unix/sysv/linux/tst-fdopendir-o_path.c Normal file
View File

@ -0,0 +1,48 @@
/* Check if fdopendir fails with file descriptor opened with O_PATH (BZ 30737)
Copyright (C) 2023 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
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <fcntl.h>
#include <dirent.h>
#include <support/check.h>
#include <support/temp_file.h>
#include <support/xunistd.h>
static int
do_test (void)
{
char *dirname = support_create_temp_directory ("tst-fdopendir-o_path");
{
int fd = xopen (dirname, O_RDONLY | O_DIRECTORY, 0600);
DIR *dir = fdopendir (fd);
TEST_VERIFY_EXIT (dir != NULL);
closedir (dir);
}
{
int fd = xopen (dirname, O_RDONLY | O_PATH | O_DIRECTORY, 0600);
TEST_VERIFY (fdopendir (fd) == NULL);
TEST_COMPARE (errno, EBADF);
xclose (fd);
}
return 0;
}
#include <support/test-driver.c>