/* Copyright (C) 1994-2018 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/>.  */

#include <sys/types.h>

#include <unistd.h>

#include <fcntl.h>

#include <errno.h>

#include <string.h>

#include <sysdep.h>

/* lockf is a simplified interface to fcntl's locking facilities.  */

int

lockf64 (int fd, int cmd, off64_t len64)

{

  struct flock64 fl64;

  int cmd64;

  int result;

  memset ((char *) &fl64, '\0', sizeof (fl64));

  fl64.l_whence = SEEK_CUR;

  fl64.l_start = 0;

  fl64.l_len = len64;

  switch (cmd)

    {

    case F_TEST:

      /* Test the lock: return 0 if FD is unlocked or locked by this process;

	 return -1, set errno to EACCES, if another process holds the lock.  */

      fl64.l_type = F_RDLCK;

      INTERNAL_SYSCALL_DECL (err);

      result = INTERNAL_SYSCALL (fcntl64, err, 3, fd, F_GETLK64, &fl64);

      if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, err)))

	return INLINE_SYSCALL_ERROR_RETURN_VALUE (INTERNAL_SYSCALL_ERRNO (result,

									  err));

      if (fl64.l_type == F_UNLCK || fl64.l_pid == __getpid ())

        return 0;

      return INLINE_SYSCALL_ERROR_RETURN_VALUE (EACCES);

    case F_ULOCK:

      fl64.l_type = F_UNLCK;

      cmd64 = F_SETLK64;

      break;

    case F_LOCK:

      fl64.l_type = F_WRLCK;

      cmd64 = F_SETLKW64;

      break;

    case F_TLOCK:

      fl64.l_type = F_WRLCK;

      cmd64 = F_SETLK64;

      break;

    default:

      return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);

    }

  return INLINE_SYSCALL (fcntl64, 3, fd, cmd64, &fl64);

}