func (fd *netFD) closeRead() error {
	if fd.fakeNetFD != nil {
		return fd.fakeNetFD.closeRead()
	}
	return os.NewSyscallError("closeRead", syscall.ENOTSUP)
}

func (fd *netFD) closeWrite() error {
	if fd.fakeNetFD != nil {
		return fd.fakeNetFD.closeWrite()
	}
	return os.NewSyscallError("closeRead", syscall.ENOTSUP)

)

func (fd *netFD) closeRead() error {
	if fd.fakeNetFD != nil {
		return fd.fakeNetFD.closeRead()
	}
	return fd.shutdown(syscall.SHUT_RD)
}

func (fd *netFD) closeWrite() error {
	if fd.fakeNetFD != nil {
		return fd.fakeNetFD.closeWrite()
	}
	return fd.shutdown(syscall.SHUT_WR)

			// read is already closed - we need to close out
			_ = closeWriter(dst)
			return
		}
	}
}

// CloseWriter is one of possible interfaces implemented by Out to send a FIN, without closing
// the input. Some writers only do this when Close is called.
type CloseWriter interface {
	CloseWrite() error
}

func closeWriter(dst io.Writer) error {
	if cw, ok := dst.(CloseWriter); ok {
		return cw.CloseWrite()
	}

// Possibility raised in the discussion of https://golang.org/cl/71973.
func TestEndlessWrite(t *testing.T) {
	t.Parallel()
	c := make(chan bool)
	server := func(cs *TCPConn) error {
		cs.CloseWrite()
		<-c
		return nil
	}
	client := func(ss *TCPConn) error {
		// Tell the server to return when we return.
		defer close(c)

		// Loop writing to the server. The server is not reading

	defer c.Close()

	var buf [128]byte
	n, err := c.Read(buf[:])
	if err != nil {
		return err
	}
	if _, err := c.Write(buf[:n]); err != nil {
		return err
	}
	if err := c.(*net.TCPConn).CloseWrite(); err != nil {
		return err
	}
	return c.Close()
}

func findListener() (net.Listener, error) {
	// We start looking for pre-opened sockets at fd=3 because 0, 1, and 2

			wg.Done()
		}()

		_, err := io.Copy(os.Stdout, conn)
		if err != nil {
			log.Printf("error while copying stream to stdout: %v", err)
		}
	}()

	go func() {
		defer func() {
			conn.CloseWrite()
			wg.Done()
		}()

		_, err := io.Copy(conn, os.Stdin)
		if err != nil {
			log.Printf("error while copying stream from stdin: %v", err)
		}
	}()

	wg.Wait()

		select {
		case p.wrCh <- b:
			nw := <-p.rdCh
			b = b[nw:]
			n += nw
		case <-p.done:
			return n, p.writeCloseError()
		}
	}
	return n, nil
}

func (p *pipe) closeWrite(err error) error {
	if err == nil {
		err = EOF
	}
	p.werr.Store(err)
	p.once.Do(func() { close(p.done) })
	return nil
}

// readCloseError is considered internal to the pipe type.

	}
	return fd.pfd.Write(fd.data.Write, b)
}

func (fd *netFD) closeRead() error {
	if !fd.ok() {
		return syscall.EINVAL
	}
	return syscall.EPLAN9
}

func (fd *netFD) closeWrite() error {
	if !fd.ok() {
		return syscall.EINVAL
	}
	return syscall.EPLAN9
}

func (fd *netFD) Close() error {
	if err := fd.pfd.Close(); err != nil {
		return err
	}
	if !fd.ok() {

	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)
	runtime.KeepAlive(fd)
	return n, wrapSyscallError(readSyscallName, err)
}

	// if needed.
	rstAvoidanceDelay = 1 * time.Nanosecond
}

// SetRSTAvoidanceDelay sets how long we are willing to wait between calling
// CloseWrite on a connection and fully closing the connection.
func SetRSTAvoidanceDelay(t *testing.T, d time.Duration) {
	prevDelay := rstAvoidanceDelay
	t.Cleanup(func() {
		rstAvoidanceDelay = prevDelay
	})