ErrDeadlineExceeded = errDeadlineExceeded() // "i/o timeout"
)

func errNoDeadline() error { return poll.ErrNoDeadline }

// errDeadlineExceeded returns the value for os.ErrDeadlineExceeded.
// This error comes from the internal/poll package, which is also
// used by package net. Doing it this way ensures that the net
// package will return os.ErrDeadlineExceeded for an exceeded deadline,

	if len(b) == 0 {
		return 0, nil
	}
	fd.rmu.Lock()
	if fd.rtimedout {
		fd.rmu.Unlock()
		return 0, ErrDeadlineExceeded
	}
	fd.raio = newAsyncIO(fn, b)
	fd.rmu.Unlock()
	n, err := fd.raio.Wait()
	fd.raio = nil
	if isHangup(err) {
		err = io.EOF
	}
	if isInterrupted(err) {
		err = ErrDeadlineExceeded
	}
	return n, err
}

// Write implements io.Writer.

func errClosing(isFile bool) error {
	if isFile {
		return ErrFileClosing
	}
	return ErrNetClosing
}

// ErrDeadlineExceeded is returned for an expired deadline.
// This is exported by the os package as os.ErrDeadlineExceeded.
var ErrDeadlineExceeded error = &DeadlineExceededError{}

// DeadlineExceededError is returned for an expired deadline.
type DeadlineExceededError struct{}

	case isClosedChan(p.readDeadline.wait()):
		return 0, os.ErrDeadlineExceeded
	}

	select {
	case bw := <-p.rdRx:
		nr := copy(b, bw)
		p.rdTx <- nr
		return nr, nil
	case <-p.localDone:
		return 0, io.ErrClosedPipe
	case <-p.remoteDone:
		return 0, io.EOF
	case <-p.readDeadline.wait():
		return 0, os.ErrDeadlineExceeded
	}
}

func (p *pipe) Write(b []byte) (int, error) {

	xerrs   [2]error // expected errors in transition
}{
	// Tests that read deadlines work, even if there's data ready
	// to be read.
	{-5 * time.Second, [2]error{os.ErrDeadlineExceeded, os.ErrDeadlineExceeded}},

	{50 * time.Millisecond, [2]error{nil, os.ErrDeadlineExceeded}},
}

// There is a very similar copy of this in os/timeout_test.go.
func TestReadTimeout(t *testing.T) {
	handler := func(ls *localServer, ln Listener) {

	if err == nil {
		t.Errorf("client reading from truncated request body: got nil error, want non-nil")
	}
	err = <-errc // io.Copy error
	if !errors.Is(err, os.ErrDeadlineExceeded) {
		t.Errorf("server timed out writing request body: got err %v; want os.ErrDeadlineExceeded", err)
	}
}

func TestResponseControllerSetPastReadDeadline(t *testing.T) {
	run(t, testResponseControllerSetPastReadDeadline)
}

		ok       bool
	)
	expired := ffd.readDeadline.Load().expired
	select {
	case <-expired:
		return nil, os.ErrDeadlineExceeded
	case incoming, ok = <-ffd.incoming:
		if !ok {
			return nil, ErrClosed
		}
		select {
		case <-expired:
			ffd.incoming <- incoming
			return nil, os.ErrDeadlineExceeded
		default:
		}
	case incoming, ok = <-ffd.incomingFull:
		select {
		case <-expired:

	//
	// If the deadline is exceeded a call to Read or Write or to other
	// I/O methods will return an error that wraps os.ErrDeadlineExceeded.
	// This can be tested using errors.Is(err, os.ErrDeadlineExceeded).
	// The error's Timeout method will return true, but note that there
	// are other possible errors for which the Timeout method will

)

func convertErr(res int, isFile bool) error {
	switch res {
	case pollNoError:
		return nil
	case pollErrClosing:
		return errClosing(isFile)
	case pollErrTimeout:
		return ErrDeadlineExceeded
	case pollErrNotPollable:
		return ErrNotPollable
	}
	println("unreachable: ", res)
	panic("unreachable")
}

// SetDeadline sets the read and write deadlines associated with fd.

			// something first, we expect to get an os.ErrDeadlineExceeded error
			// here if the connection is still alive.
			// note that unlike tcp connections, reading is a good enough test here.
			_, err := conn.readMessage(time.Second / 100)
			switch {
			case !errors.Is(err, os.ErrDeadlineExceeded):
				log.Debugf("ztunnel keepalive failed: %v", err)
				if errors.Is(err, io.EOF) {