Plone/Zope: Truncating a Data.fs back to a certain date/time

// under data.fs database date fix linux plone python time truncate zeo zodb zodb3 zope

Okay. So, anyone out here who’s listening — particularly those overly-enthusiastic users — don’t try to recursively wget your Plone site (or other CMS, for that matter) whilst you’re logged in with an account that can make edits. It will lead to a very bad situation where your site administrator and technical team need to step in and fix your mistakes. For the uninitiated, a loose recursive wget (when logged in with some degree of Edit rights) will hit every link that’s on your pages, and I mean in the (X)HTML source. For a Plone site, this means hitting every “Edit” link, every “Revert to this version” link, and every other link that might be dangerous when clicked randomly. Oh, and if the account you’ve got has admin rights, well, it’s not getting any better and requires the Data.fs to be undone back to before it happened. Here’s how to do that easily.

So enough of the backstory. How to fix a suitably bollocks’d Data.fs? Well, the easy answer is to recover from a backup. Of course you’ve got plenty of those, right? No? Oh dear. Never to stress, you can use your existing Data.fs file and strip away any number of transactions, to bring your file back to any date, time, or transaction you’d like.

Realise you’ll be losing everything from now back until then, so take a copy of data off your Plone site, back up your Data.fs (twice, if need be), and make it crystal clear to your users changes are going bye-by.
Figure out when you want to go back to. If you want a particular transaction, consider checking your Zope Undo log to locate the specific date/time of a given transaction. Otherwise, figure out the date and time. Then, convert that date and time to UTC as that what date/times are in the Data.fs. In Queensland, Australia, we’re +10 hours.
Shut down ZEO if it’s still running.
Edit parts/zope2/lib/python/ZODB/FileStorage/fsdump.py, and add this to allow you to run this file:
```
if __name__ == "__main__":
    main()
```
Get your PYTHONPATH sorted for running this file. Consider ./bin/instance1 shell, if you’ve got a Plone instance, or using zopepy. Manually update it if necessary.
Run the the fsdump.py script thusly, substituting the date for yours (or a date/time):
```
./bin/python parts/zope2/lib/python/ZODB/FileStorage/fsdump.py var/filestorage/Data.fs | grep 2010-07-12
```
This will tell you exactly the offset you need to truncate the Data.fs file.
Take that offset amount and truncate your Data.fs file, inserting the number after “seek=”:
```
dd if=/dev/zero of=var/filestorage/Data.fs seek=199340531 bs=1 count=0
```
Restart your ZEO service and re-connect to it from your Plone/Zope instance. Your database should be back to the date and time you specified. If it’s close, but not quite right, check your times and that they’re UTC.
Get some backups and politely ask your users to think twice about any such consequences next time.

And we’re done!

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