if fd == syscall.InvalidHandle {
		return nil
	}

	err := lockFileEx(fd, flags, 1, 0, &syscall.Overlapped{})
	if err == nil || err == errLockViolation {
		return nil
	}
	if err.Error() == "The process cannot access the file because another process has locked a portion of the file." {
		return ErrAlreadyLocked
	}
	return err
}