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From:	Qian Hong <fracting AT gmail DOT com>
Date:	Tue, 8 Sep 2015 13:54:02 +0800
Message-ID:	<CALd+sZSspE2pn-tvX+fCkK93h1GVy+Yaf_8DAU4KAmYnKZmMYw@mail.gmail.com>
Subject:	Re: Question about flock - potential memory corruption?
To:	cygwin <cygwin AT cygwin DOT com>
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Hi Sam,

Thank you very much for your reply!

On Tue, Sep 8, 2015 at 12:41 PM, Sam Edge <sam DOT edge AT dwalin DOT fsnet DOT co DOT uk> wrote:
> Erm ... slight technical hitch? Your example flock.c doesn't call
> fork(), nor does it use your two macros MAX_ITER & CHILDREN.

Good question. This problem was originally found when running autom4te on Wine.

In autom4te-2.69, we have:
 68 my $flock_implemented = 'yes';
 982 $icache_file = new Autom4te::XFile $icache, O_RDWR|O_CREAT;
 983 $icache_file->lock (LOCK_EX)
 984   if ($flock_implemented eq "yes");

This cause problem on Wine on some machine, while it works fine on
some other machine.

After tracking down, I successfully reproduce the problem with Cygwin
using the attached test case stc-flock-fork-2.c, which is changed
based on another test case from an old cygwin mailing list archive
[1].

Later then, I found that even without fork(), we can still reproduce
the same problem, Valgrind + Wine shows same warning either with or
without fork, so I simply the test case a bit further, that's why you
didn't see fork in my test case.

Thank for your comment, it's good to make things clearer to everybody.

Any further comment is welcome!

[1] https://www.cygwin.com/ml/cygwin/2011-08/txt00012.txt

-- 
Regards,
Qian Hong

-
http://www.winehq.org

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