panic("net/http: CloseNotify called after ServeHTTP finished")
	}
	return w.closeNotifyCh
}

func registerOnHitEOF(rc io.ReadCloser, fn func()) {
	switch v := rc.(type) {
	case *expectContinueReader:
		registerOnHitEOF(v.readCloser, fn)
	case *body:
		v.registerOnHitEOF(fn)
	default:
		panic("unexpected type " + fmt.Sprintf("%T", rc))
	}
}

}

// bodyRemains reports whether future Read calls might
// yield data.
func (b *body) bodyRemains() bool {
	b.mu.Lock()
	defer b.mu.Unlock()
	return !b.sawEOF
}

func (b *body) registerOnHitEOF(fn func()) {
	b.mu.Lock()
	defer b.mu.Unlock()
	b.onHitEOF = fn
}

// bodyLocked is an io.Reader reading from a *body when its mutex is
// already held.
type bodyLocked struct {
	b *body