Fix dup for /dev/dsp

Igor Pechtchanski
Sun Jul 18 16:29:00 GMT 2004

On Sun, 18 Jul 2004, Gerd Spalink wrote:

> What I did:
> The static open_count is no longer needed because now we consistently
> use the return status from the windows API to decide if we can open or
> not.  This change is not related to dup.
> Wave header parsing needed a small fix. It was a +/-1 problem.
> To fix all cases of dup, a dup_chain is maintained to keep all duped
> instances consistent. I did not understand how to apply archetypes for
> this problem, and this solution works (test suite contribution is in
> separate patch).
> ChangeLog:
> 2004-07-18 Gerd Spalink <>
> 	* fhandler.h (class fhandler_dev_dsp): Remove static open_count,
> 	add members to keep track of duped instances.
> 	* (fhandler_dev_dsp::Audio_out::parsewav): Compare
> 	with <= end for the case that only the header is passed to write.
> 	(fhandler_dev_dsp::open): Remove open_count; instead of query use
> 	start/stop to get wave device status from win32.
> 	(fhandler_dev_dsp::fhandler_dev_dsp): Initialize new members
> 	dup_chain_next and dup_chain_prev.
> 	(fhandler_dev_dsp::write): Insert call to update_duped.
> 	(fhandler_dev_dsp::close): Check dup_chain before stop of audio
> 	device.
> 	(fhandler_dev_dsp::dup): Create dup_chain linked list. Copy members
> 	by calling dup_cpy.
> 	(fhandler_dev_dsp::dup_cpy): New.
> 	(fhandler_dev_dsp::update_duped): New.
> 	(fhandler_dev_dsp::ioctl): Replace all inline return statements by
> 	setting variable rc. At the end, reflect any changes in duped instances
> 	by calling update_duped ().


I don't have time for an in-depth analysis, but after a quick look-over,
it looks like you're effectively keeping a reference_count, though as a
full list of references instead of just a count.  It looks a bit
heavyweight, but otherwise good, and I can't argue with success.  Just my
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