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Date: Tue, 19 Feb 2013 15:46:00 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
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Subject: Re: non-blocking accept() can hang.
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On Feb 12 10:52, Tanaka Akira wrote:
> 2013/2/8 marco atzeri <marco DOT atzeri AT gmail DOT com>:
> 
> > you can also test by yourself
> > http://cygwin.com/snapshots/
> 
> I see.  I re-tested after replacing /bin/cygwin1.dll.
> 
> Unfortunately, the program still block.
> (Good news is that ^C is effective.
> I don't need to kill the process using Windows task manager.)

Sorry for the late response, but I'm pretty busy with porting Cygwin to
64 bit right now.

I debugged your example code, and it can't work on Cygwin.  The problem
is that accept/connect on AF_LOCAL sockets performs a handshake
operation to make sure that the other side of the socket is a Cygwin
process as well, and to propagate credential information between
client and listener.  The way it's implemented right now requires that
both sides of the socket are responsive.  That's a safe thing for the
accept call here, but since there's neither a blocking connect, nor a
select or poll call waiting on the connecting side of the socket, nothing
goes forward.

To get this code working, you have to use either AF_INET or AF_INET6
sockets, or you have to start a thread calling select or poll, so
there's an active function call which allows to perform the handshake
from the connecting side.


HTH,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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