Re: Packing problems: fixed

Toby Dickenson <[email protected]>
Newsgroups gmane.comp.web.zope.zodb.dirstorage
Message-ID <[email protected]>
On Tuesday 09 November 2004 11:47, Matt Hamilton wrote:

> I guess the main question is: Why did DirectoryStorage not fail during 
> the pack if it could not mark/read the files?

Congratulations. Youve just uncovered the first data-loss bug since 
DirectoryStorage hit "1.0" nearly three years ago.

The class _PermissionsMarker in PosixFilesystem.py contains an explicit 
comparison against file owner and process uid. It 'conservatively' reports 
that any files not owned by the current process uid are marked. Thats the 
right thing to do during the 'sweep' phase since marked files are left alone. 
It is *not* the right thing to do during the 'mark' phase since the objects 
referenced by that one will not get scanned.

You must have a root-owned object reachable only by references from objects 
not owned by root. You will be safe now all your files have the same owner.

> Luckily we could just rename all the -deleted files back 
> and we were OK.

Events like this are what disaster-recovery features are made for ;-)

-- 
Toby Dickenson

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