Each opendevice() must eventually be matched by a call to closedevice().
All I/O requests must be complete before CloseDevice().  If any requests
are still pending, abort them with abortio():

   if (!(CheckIO(InputIO)))
       {
       AbortIO(InputIO);  /* Ask device to abort request, if pending */
       }
   WaitIO(InputIO);       /* Wait for abort, then clean up */
   CloseDevice((struct IORequest *)InputIO);