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X-Authentication-Warning: myth8.Stanford.EDU: cobbler owned process doing -bs
Date: Fri, 15 Dec 2000 17:38:09 -0800 (PST)
From: Dan Morris <cobbler AT stanford DOT edu>
Reply-To: dmorris AT tiqit DOT com
To: cygwin-developers AT sources DOT redhat DOT com
Subject: Serial blocking read
Message-ID: <Pine.GSO.4.21.0012151727280.7629-100000@myth8.Stanford.EDU>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII

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