switch flag {
	case syscall.O_RDONLY:
		lockType = syscall.F_RDLCK
	case syscall.O_WRONLY:
		fallthrough
	case syscall.O_RDWR:
		fallthrough
	case syscall.O_WRONLY | syscall.O_CREAT:
		fallthrough
	case syscall.O_RDWR | syscall.O_CREAT:
		lockType = syscall.F_WRLCK
	default:
		return nil, &os.PathError{
			Op:   "open",
			Path: path,
			Err:  syscall.EINVAL,
		}
	}

	lock := syscall.Flock_t{