X-Recipient:	archive-cygwin AT delorie DOT com
X-Spam-Check-By:	sourceware.org
Date:	Tue, 14 Sep 2010 18:16:36 +0200
From:	Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To:	cygwin AT cygwin DOT com
Subject:	Re: 1.7.5: Occasional failure of CreatePipe or signal handing due to thread-unsafe code in cwdstuff::set
Message-ID:	<20100914161636.GH15121@calimero.vinschen.de>
Reply-To:	cygwin AT cygwin DOT com
Mail-Followup-To:	cygwin AT cygwin DOT com
References:	<20100812081151 DOT GT14202 AT calimero DOT vinschen DOT de> <3C031C390CBF1E4A8CE1F74DE7ECAF3A158EDA702A AT MBX8 DOT EXCHPROD DOT USA DOT NET> <20100903073740 DOT GA1749 AT calimero DOT vinschen DOT de> <3C031C390CBF1E4A8CE1F74DE7ECAF3A158EDA702D AT MBX8 DOT EXCHPROD DOT USA DOT NET> <20100904092626 DOT GE16534 AT calimero DOT vinschen DOT de> <3C031C390CBF1E4A8CE1F74DE7ECAF3A158EDA704C AT MBX8 DOT EXCHPROD DOT USA DOT NET> <20100911103010 DOT GM16534 AT calimero DOT vinschen DOT de> <3C031C390CBF1E4A8CE1F74DE7ECAF3A15945FDD78 AT MBX8 DOT EXCHPROD DOT USA DOT NET> <20100914081225 DOT GE16534 AT calimero DOT vinschen DOT de> <20100914161138 DOT GG15121 AT calimero DOT vinschen DOT de>
MIME-Version:	1.0
In-Reply-To:	<20100914161138.GG15121@calimero.vinschen.de>
User-Agent:	Mutt/1.5.20 (2009-06-14)
Mailing-List:	contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id:	<cygwin.cygwin.com>
List-Unsubscribe:	<mailto:cygwin-unsubscribe-archive-cygwin=delorie DOT com AT cygwin DOT com>
List-Subscribe:	<mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive:	<http://sourceware.org/ml/cygwin/>
List-Post:	<mailto:cygwin AT cygwin DOT com>
List-Help:	<mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender:	cygwin-owner AT cygwin DOT com
Mail-Followup-To:	cygwin AT cygwin DOT com
Delivered-To:	mailing list cygwin AT cygwin DOT com

On Sep 14 18:11, Corinna Vinschen wrote:
> On Sep 14 10:12, Corinna Vinschen wrote:
> > On Sep 13 19:47, John Carey wrote:
> > > Anyway, it looks to me as if overwriting the path in an existing
> > > VistaCwd instance would confuse RtlGetCurrentDirectory_U() and
> > > probably other Win32 API functions.  (It may be that the same is
> > > true for the handle member; I have not tried to find that out.)
> > > Cygwin should probably allocate a new VistaCwd instance,
> > > as does the Win32 SetCurrentDirectory() implementation.
> > 
> > Hmm, I'm still wondering.  In theory we don't have to replace the
> > directory name.  We just have to InterlockedExchange the handle, since
> > we only need to replace the original handle which does not allow
> > sharing-for-delete with our own handle which does.
> > 
> > All other border cases (virtual dir, directory with restricted rights)
> > can be rightfully handled by setting the Win32 CWD to \\?\PIPE\ again.
> > 
> > That's at least worth a try, isn't it?
> 
> I applied the below patch to Cygwin CVS and it appears to work nicely.

Sorry, that wasn't what I was trying to say.  Actually, I'm using this
code just locally for now and put it up here for discussion and for
curious testers.  I intend to apply it only, if we can agree that it's
sufficient.

> The only potential race I can think of is, if another thread of the same
> Cygwin process calls SetCurrentDirectory.  I'm inclined to let this
> situation slip through the cracks since SetCurrentDirectory will already
> mess up a mixed-mode Cygwin process.
> 
> The "wincap.has_transactions ()" is just for testing.  If we can use
> that code, I would replace is with something like
> "wincap.has_messed_up_cwd_handling()" or so.


Corinna

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

--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple

- Raw text -