// so this must be executed before CloseFunc.
	fd.pd.close()

	err := fd.SysFile.destroy(fd.Sysfd)

	fd.Sysfd = -1
	runtime_Semrelease(&fd.csema)
	return err
}

// Close closes the FD. The underlying file descriptor is closed by the
// destroy method when there are no remaining references.
func (fd *FD) Close() error {
	if !fd.fdmu.increfAndClose() {
		return errClosing(fd.isFile)
	}

}

func setDeadlineImpl(fd *FD, t time.Time, mode int) error {
	d := t.Sub(time.Now())
	if mode == 'r' || mode == 'r'+'w' {
		fd.rmu.Lock()
		defer fd.rmu.Unlock()
		if fd.rtimer != nil {
			fd.rtimer.Stop()
			fd.rtimer = nil
		}
		fd.rtimedout = false
	}
	if mode == 'w' || mode == 'r'+'w' {
		fd.wmu.Lock()
		defer fd.wmu.Unlock()
		if fd.wtimer != nil {
			fd.wtimer.Stop()

		err := syscall.WSAIoctl(fd.Sysfd, syscall.SIO_UDP_CONNRESET, (*byte)(unsafe.Pointer(&flag)), size, nil, 0, &ret, nil, 0)
		if err != nil {
			return "wsaioctl", err
		}
	}
	fd.rop.mode = 'r'
	fd.wop.mode = 'w'
	fd.rop.fd = fd
	fd.wop.fd = fd
	fd.rop.runtimeCtx = fd.pd.runtimeCtx
	fd.wop.runtimeCtx = fd.pd.runtimeCtx
	return "", nil
}

func (fd *FD) destroy() error {

			return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
		}
	} else if err := setKeepAliveIdleAndInterval(c.fd, config.Idle, config.Interval); err != nil {
		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	if err := setKeepAliveCount(c.fd, config.Count); err != nil {
		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}

func (fd *FD) SetDeadline(t time.Time) error {
	return setDeadlineImpl(fd, t, 'r'+'w')
}

// SetReadDeadline sets the read deadline associated with fd.
func (fd *FD) SetReadDeadline(t time.Time) error {
	return setDeadlineImpl(fd, t, 'r')
}

// SetWriteDeadline sets the write deadline associated with fd.
func (fd *FD) SetWriteDeadline(t time.Time) error {

	if err != nil {
		return nil, err
	}

	switch fd.laddr.(type) {
	case *TCPAddr:
		return newTCPConn(fd, defaultTCPKeepAliveIdle, KeepAliveConfig{}, testPreHookSetKeepAlive, testHookSetKeepAlive), nil
	case *UDPAddr:
		return newUDPConn(fd), nil
	}
	return nil, syscall.EPLAN9
}

func fileListener(f *os.File) (Listener, error) {
	fd, err := newFileFD(f)

	if !c.ok() {
		return syscall.EINVAL
	}
	err := c.fd.pfd.RawRead(f)
	runtime.KeepAlive(c.fd)
	if err != nil {
		err = &OpError{Op: "raw-read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	return err
}

func (c *rawConn) Write(f func(uintptr) bool) error {
	if !c.ok() {
		return syscall.EINVAL
	}
	err := c.fd.pfd.RawWrite(f)
	runtime.KeepAlive(c.fd)
	if err != nil {

		return syscall.EINVAL
	}

	if err := setKeepAlive(c.fd, config.Enable); err != nil {
		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	if err := setKeepAliveIdle(c.fd, config.Idle); err != nil {
		return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	if err := setKeepAliveInterval(c.fd, config.Interval); err != nil {

		return nil, syscall.EINVAL
	}
	return newRawConn(c.fd), nil
}

// CloseRead shuts down the reading side of the Unix domain connection.
// Most callers should just use Close.
func (c *UnixConn) CloseRead() error {
	if !c.ok() {
		return syscall.EINVAL
	}
	if err := c.fd.closeRead(); err != nil {
		return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
	}
	return nil
}

	"runtime"
	"syscall"
)

// Writev wraps the writev system call.
func (fd *FD) Writev(v *[][]byte) (int64, error) {
	if err := fd.writeLock(); err != nil {
		return 0, err
	}
	defer fd.writeUnlock()
	if err := fd.pd.prepareWrite(fd.isFile); err != nil {
		return 0, err
	}

	var iovecs []syscall.Iovec
	if fd.iovecs != nil {
		iovecs = *fd.iovecs
	}
	// TODO: read from sysconf(_SC_IOV_MAX)? The Linux default is