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Message-ID: <3A352393.4D8645EC@delcomsys.com>
Date: Mon, 11 Dec 2000 13:57:23 -0500
From: Patrick Doyle <wpd AT delcomsys DOT com>
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To: cygwin AT cygwin DOT com
Subject: Re: Why does scp leave ssh running? -- select() never returns
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Christopher Faylor wrote:
> 
> On Mon, Dec 11, 2000 at 01:20:14PM -0500, Patrick Doyle wrote:
> >So far, the most elegant solution I have come up with is to reimplement
> >'select()' so that it calls 'ReadFileEx()' with a suitable 'OVERLAPPED'
> >structure, thus eliminating the separate thread that wakes up every 10
> >ms.  Of course, if I read a byte from the pipe, I would have to buffer
> >it somewhere and fix 'read()' so that it checks for the "readahead" byte
> >first, but that is basically solvable.  If the call to 'select()'
> >returned for some other reason (i.e. another fd was made ready), then
> >call 'CancelIo()' to terminate the asynchronous read.
> 
> I'm pretty sure that overlapped I/O does not work with any flavor of pipe.
> It should be possible to make a simple test case, to verify though.
> 
My question is more of a philosophical one.  If I try it, and it happens
to work on my W98 box, but it is listed as "unsupported" in the official
Microsoft documentation, would you still want to incorporate it into
cygwin?  On the one hand, I can understand the SQA argument that you
would not want the behavior of cygwin to depend upon undocumeneted or
unsupported features of Windows.  On the other hand, I expect that the
behavior of Windows 9x is what it is, and it will never change from
here, so if we find a loophole, we might as well use it -- for Windows
9x _only_.

But, based on your comment, if I try it, and it doesn't work, my first
inclination will be that "it doesn't work because it is unsupported",
rather than my default inclination of "it doesn't work because I did
something wrong".  When that happens, I think I will start down the path
of implementing the parallel pipe for OOB data.

What an ugly mess this has turned out to be!  Thanks for your comments.

--wpd

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