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Date: Tue, 22 Sep 2009 22:56:58 +0100
From: Dave Korn <dave DOT korn DOT cygwin AT googlemail DOT com>
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Subject: Re: 1.7 beta vs MSSE-- breaks 'cvs co', apparently on rename()
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John Hood wrote:
> I'm having a problem with 1.7 beta on Windows XP with the Microsoft
> Security Essentials public beta installed.
> 
> Microsoft Security Essentials Version: 1.0.1500.0
> 
> If I try 'cvs co <modulename>' or 'cvs up', CVS will run for a while but
> eventually exit with
> 
>     cvs [checkout aborted]: cannot rename file CVS/Entries.Backup to
> CVS/Entries: Permission denied
> 
> (and this is somewhat heinous if you're updating, because if you run an
> update again in this state, CVS loses any usable CVS/Entries file, and
> neither you nor it can tell what you've got in the working dir.  So
> don't try and reproduce this problem on a valuable CVS work dir.)
> 
> If I uncheck "Turn on real-time protection" in the MSSE Settings tab,
> things work OK.
>
> strace indicates that rename() is failing on a Windows error.  There
> seems to be some variation in how far it gets before failing.  Sometimes
> strace makes the problem much rarer and cvs gets much further.  It does
> look more like an MSSE bug than a Cygwin bug, but this seems like the
> best first place to report it.

  This is a well known bug in antivirus scanners etc., and MSSE isn't the only
one.  The problem is that after the original file ("Entries.Backup" in the
above example) has been written the application closes it and then attempts to
rename it in place to its final name.  Unfortunately, the buggy AV scanner has
kept open a handle to the file - after the application believes the file to be
closed - and because there is still an open handle on the file, the rename
operation fails.

  There's not much we can do except add MSSE to the BLODA, and advise people
that disabling the real-time protection is the only known workaround.

    cheers,
      DaveK



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