// exported APIs (now we've got some in net.rawConn) which are only used
// internally and are not intended to be used outside the standard libraries,
// Therefore, we make those APIs use internal types like poll.FD or poll.String
// in their function signatures to disable the usability of these APIs from
// external codebase.

	// 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()

	}
	return netfd, nil
}

func (fd *netFD) setAddr(laddr, raddr Addr) {
	fd.laddr = laddr
	fd.raddr = raddr
	runtime.SetFinalizer(fd, (*netFD).Close)
}

func (fd *netFD) Close() error {
	if fd.fakeNetFD != nil {
		return fd.fakeNetFD.Close()
	}
	runtime.SetFinalizer(fd, nil)
	return fd.pfd.Close()
}

func (fd *netFD) shutdown(how int) error {
	if fd.fakeNetFD != nil {
		return nil
	}

		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 fd, nil
}

func (fd *netFD) ctrlNetwork() string {
	switch fd.net {
	case "unix", "unixgram", "unixpacket":
		return fd.net
	}
	switch fd.net[len(fd.net)-1] {
	case '4', '6':
		return fd.net
	}
	if fd.family == syscall.AF_INET {
		return fd.net + "4"
	}
	return fd.net + "6"
}

	return fd.pfd.Close()
}

func (fd *netFD) shutdown(how int) error {
	err := fd.pfd.Shutdown(how)
	runtime.KeepAlive(fd)
	return wrapSyscallError("shutdown", err)
}

func (fd *netFD) closeRead() error {
	return fd.shutdown(syscall.SHUT_RD)
}

func (fd *netFD) closeWrite() error {
	return fd.shutdown(syscall.SHUT_WR)
}

func (fd *netFD) Read(p []byte) (n int, err error) {
	n, err = fd.pfd.Read(p)

	return ENOSYS
}

func Accept(fd int) (int, Sockaddr, error) {
	var newfd int32
	errno := sock_accept(int32(fd), 0, unsafe.Pointer(&newfd))
	return int(newfd), nil, errnoErr(errno)
}

func Connect(fd int, sa Sockaddr) error {
	return ENOSYS
}

func Recvfrom(fd int, p []byte, flags int) (n int, from Sockaddr, err error) {
	return 0, nil, ENOSYS
}

package unix

// Set adds fd to the set fds.
func (fds *FdSet) Set(fd int) {
	fds.Bits[fd/NFDBITS] |= (1 << (uintptr(fd) % NFDBITS))
}

// Clear removes fd from the set fds.
func (fds *FdSet) Clear(fd int) {
	fds.Bits[fd/NFDBITS] &^= (1 << (uintptr(fd) % NFDBITS))
}

// IsSet returns whether fd is in the set fds.
func (fds *FdSet) IsSet(fd int) bool {
	return fds.Bits[fd/NFDBITS]&(1<<(uintptr(fd)%NFDBITS)) != 0
}

			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}
	}