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Date: Tue, 20 Mar 2001 22:37:56 +0000 (GMT)
From: David Woodhouse <dwmw2@infradead.org>
To: Doug Ledford <dledford@redhat.com>
cc: David Ford <david@blue-labs.org>, Peter Lund <firefly@netgroup.dk>,
        Pozsar Balazs <pozsy@sch.bme.hu>, <linux-kernel@vger.kernel.org>
Subject: Re: esound (esd), 2.4.[12] chopped up sound -- solved
In-Reply-To: <3AB7BB59.9513514C@redhat.com>
Message-ID: <Pine.LNX.4.30.0103202159470.13996-100000@imladris.demon.co.uk>
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On Tue, 20 Mar 2001, Doug Ledford wrote:

> Why would esd get a short write() unless it is opening the file in non
> blocking mode (which I didn't see when I was working on the i810 sound
> driver)?  If esd is writing to a file in blocking mode and that write is
> returning short, then that sounds like a driver bug to me.

Please quote chapter and verse.

I'm looking at http://www.opengroup.org/onlinepubs/7908799/xsh/write.html 
and cannot see anything which states that write may not return having 
written fewer data than it was asked to.

The only vaguely relevant text I see is...

	Write requests to a pipe or FIFO will be handled the same as a
	regular file with the following exceptions:

	<...>

	* If the O_NONBLOCK flag is clear, a write request may cause the 
	  thread to block, but on normal completion it will return
	  nbyte.

This being an _exception_ clearly implies that for file descriptors other 
than pipes and fifos, it is _not_ necessary to return nbyte on normal 
completion.

Applications (and also I believe glibc) which assume otherwise are, 
technically, broken. Despite being numerous.

-- 
dwmw2


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