glibc/io/tst-fchmod-errors.c
Florian Weimer 3844cdc330 io: Fix destructive nature of tst-fchmod-errors
We must not change the permissions of /dev/null if running
as root.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2024-08-30 22:30:05 +02:00

64 lines
1.8 KiB
C

/* Test various fchmod error cases.
Copyright (C) 2024 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 <stdio.h>
#include <support/check.h>
#include <support/xunistd.h>
#include <unistd.h>
static int
do_test (void)
{
{
/* Permissions on /dev/null (the opened descriptor) cannot be changed. */
int fd = xopen ("/dev/null", O_RDWR, 0);
if (getuid () == 0)
puts ("info: /dev/null fchmod test skipped because of root privileges");
else
{
errno = 0;
TEST_COMPARE (fchmod (fd, 0), -1);
TEST_COMPARE (errno, EPERM);
}
xclose (fd);
/* Now testing an invalid file descriptor. */
errno = 0;
TEST_COMPARE (fchmod (fd, 0600), -1);
TEST_COMPARE (errno, EBADF);
}
errno = 0;
TEST_COMPARE (fchmod (-1, 0600), -1);
TEST_COMPARE (errno, EBADF);
errno = 0;
TEST_COMPARE (fchmod (AT_FDCWD, 0600), -1);
TEST_COMPARE (errno, EBADF);
/* Linux supports fchmod on pretty much all file descriptors, so
there is no check for failure on specific types of descriptors
here. */
return 0;
}
#include <support/test-driver.c>