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Date: Thu, 4 Jul 2002 14:13:59 +0200
From: Corinna Vinschen <vinschen AT redhat DOT com>
To: cygwin-developers AT cygwin DOT com
Subject: Re: Interruptable connect
Message-ID: <20020704141359.S21857@cygbert.vinschen.de>
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On Thu, Jul 04, 2002 at 01:54:33PM +0200, Thomas Pfaff wrote:
> 
> I am trying to get an interruptable connect and i have some difficulties.
> 
> The main problem is that it seems to be impossible to cancel a nonblocking
> connect other than closing the socket. I already thought about closing the
> socket and replacing it with a new one, but this requires that all
> sockoptions and states have to be restored for the new one execpt the
> pending connect.
> 
> Another possibility is to set errno to EINTR, return and let the
> connect keep going.
> The app can now react in different ways :
> 
> The signal handler terminates the program.
> Perfect.
> 
> The program checks for the error and close the socket.
> Good.
> 
> connect is called in a loop like
> do {
>   res = connect(...);
>   if (!res)
>     break;
> } while(errno==EINTR);
> Now the program returns to the connect function, the real connect returns
> WSAEALREADY or WSAEISCONN, it can be checked that the connect was
> interrupted and it can be continued.
> No big deal.
> 
> The error is ignored and the socket is not closed:
> Now there are 2 possibilies.
> 
> a. The connect fails.
> No problem.
> 
> b. The connect succeds. Now exists an orphaned connection that can block
> the partner.
> Sigh.
> 
> Any suggestions ?

Could you start a thread waiting for the result of the connect
and close it if it isn't already closed?

Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Developer                                mailto:cygwin AT cygwin DOT com
Red Hat, Inc.