Serial blocking read

Dan Morris cobbler@stanford.edu
Fri Dec 15 17:38:00 GMT 2000


Has anyone else had problems with serial port reads blocking even when
O_NONBLOCK is passed to _read in the 1.1.6-1 DLL?

I noticed that my reads were appropriately non-blocking most of the time, but
blocked whenever "overlapped_armed" was set, because in this case raw_read
never finds out how many bytes are in the serial port's buffer.  This patch
seems to fix the problem for me :

121a122,128
>       if (overlapped_armed) {
>           if (!ClearCommError (get_handle (), &ev, &st))
> 	          goto err;
>           else if (st.cbInQue)
>             inq = st.cbInQue;
>       }
> 

If anyone else has found a better solution to this problem, let me know...
otherwise perhaps this patch will fix things.

-Dan
 
Dan Morris
http://techhouse.brown.edu/dmorris

Tiqit Computers
http://www.tiqit.com




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