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Date: Wed, 14 Apr 2010 07:58:59 -0700
From: David Rothenberger <daveroth AT acm DOT org>
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To: cygwin AT cygwin DOT com
Subject: Re: configure test for accept4 hangs
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On 4/13/2010 12:58 PM, Corinna Vinschen wrote:
> On Apr 13 21:20, Corinna Vinschen wrote:
>> On Apr 13 10:43, David Rothenberger wrote:
>>> While configuring apr-1.4.2 with Cygwin 1.7.5, the test for accept4
>>> hung. I don't know much about this API, so I've just disabled it in
>>> libapr1 for now, but I wanted to report the hang in case it was a
>>> Cygwin bug.
>>
>> Boy, this testcase is really stressing the limits.
>>
>> The problem is that connect() is called in that loop so fast, that at
>> one point the AF_UNIX socket file already exists, but is not yet filled
>> with the information necessary to be recognized as AF_UNIX socket.
>> Consequentially, at that point connect() fails with EBADF, since it
>> assumes you're trying to connect to a file which is not a socket.
>>
>> The hang is just a followup effect due to the parent waiting in accept()
>> for a connect() which will never happen, because the child process
>> already left the connect() loop.
>>
>> I try to come up with a more robust solution which also catches this
>> scenario.
> 
> In CVS I just changed the way the socket file gets created in bind() and
> the way it's tested for being a socket file in connect() so this timing
> problem shouldn't occur anymore.  Would you mind to test either CVS or
> the next developers snapshot from http://cygwin.com/snapshots/ ?

The configure succeeds with the developers snapshot, as do the APR
tests. Thanks for the fix.

-- 
David Rothenberger  ----  daveroth AT acm DOT org

"Buy land.  They've stopped making it."
                -- Mark Twain

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