registerControlFd :: EventManager -> Fd -> Event -> IO ()
registerControlFd mgr fd evs =
  failOnInvalidFile "registerControlFd" fd $
  I.modifyFd (emBackend mgr) fd mempty evs
registerControlFd :: EventManager -> Fd -> Event -> IO ()
registerControlFd mgr fd evs =
  failOnInvalidFile "registerControlFd" fd $
  I.modifyFd (emBackend mgr) fd mempty evs
registerControlFd mgr fd evs =
  failOnInvalidFile "registerControlFd" fd $
  I.modifyFd (emBackend mgr) fd mempty evs