glibc/sysdeps/unix/sysv/linux/tst-ofdlocks.c

/* Check non representable OFD locks regions in non-LFS mode (BZ #20251)
   Copyright (C) 2018-2020 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation; either version 2
   of the License, or (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, see <https://www.gnu.org/licenses/>.
*/

#include <unistd.h>
#include <fcntl.h>
#include <stdint.h>
#include <errno.h>

#include <support/temp_file.h>
#include <support/check.h>

static char *temp_filename;
static int temp_fd;

static void
do_prepare (int argc, char **argv)
{
  temp_fd = create_temp_file ("tst-ofdlocks.", &temp_filename);
  TEST_VERIFY_EXIT (temp_fd != -1);
}

#define PREPARE do_prepare

static int
do_test (void)
{
  /* It first allocates a open file description lock range which can not
     be represented in a 32 bit struct flock.   */
  struct flock64 lck64 = {
    .l_type   = F_WRLCK,
    .l_whence = SEEK_SET,
    .l_start  = (off64_t)INT32_MAX + 1024,
    .l_len    = 1024,
  };
  int ret = fcntl64 (temp_fd, F_OFD_SETLKW, &lck64);
  if (ret == -1 && errno == EINVAL)
    /* OFD locks are only available on Linux 3.15.  */
    FAIL_UNSUPPORTED ("fcntl (F_OFD_SETLKW) not supported");

  TEST_VERIFY_EXIT (ret == 0);

  /* Open file description locks placed through the same open file description
     (either by same file descriptor or a duplicated one created by fork,
     dup, fcntl F_DUPFD, etc.) overwrites then old lock.  To force a
     conflicting lock combination, it creates a new file descriptor.  */
  int fd = open64 (temp_filename, O_RDWR, 0666);
  TEST_VERIFY_EXIT (fd != -1);

  /* It tries then to allocate another open file descriptior with a valid
     non-LFS bits struct flock but which will result in a conflicted region
     which can not be represented in a non-LFS struct flock.  */
  struct flock lck = {
    .l_type   = F_WRLCK,
    .l_whence = SEEK_SET,
    .l_start  = INT32_MAX - 1024,
    .l_len    = 4 * 1024,
  };
  int r = fcntl (fd, F_OFD_GETLK, &lck);
  if (sizeof (off_t) != sizeof (off64_t))
    TEST_VERIFY (r == -1 && errno == EOVERFLOW);
  else
    TEST_VERIFY (r == 0);

  return 0;
}

#include <support/test-driver.c>