Filesystem corruption in ReactOS when Firefox is updated

[Dimitrij Klingbeil]

Hi all

I'd like to report a bug, but can't figure out how to do this properly. Jira 
requires being a registered user but does not tell how exactly one is 
supposed to get that registration. I hope you have some other, more 
user-friendly way for reporting bugs by "normal" users - people not so 
intimate with the ReactOS development - or that you at least plan to provide 
such a way in the near future.

Anyway, here's what I think warrants looking into in more detail: Apparently 
there is still something that corrupts fastfat - triggerable from user-mode 
programs. The automatic update function of Firefox (as well as other 
derivatives like Pale Moon) seems to trigger a particularly nasty instance 
of that. I think that if a new ReactOS version is going to be released now, 
it will cause a lot of spurious bug reports from users that install Firefox 
(it's a popular program after all), and wreck FastFAT during an update in 
the background. In fact, many users may not be aware of the connection as 
Firefox tends to update itself in a stealthy way and the user does not 
really get to see what happens.

Steps to reproduce:
- install Firefox (or Palemoon, any version from the last couple of years, 
except of course the latest one)
- open the about dialog in it
- it will start downloading an update
- it will copy the update into a temporary dir in the firefox install dir
- it will prompt the user for a restart
- look into the Firefox install dir, you will find (among other things) an 
"update" subdir with temporary files, but so far everything looks OK
- now click restart in prompt
- it will do some filesystem operations for some seconds, quit, but not 
restart
- look into the install dir again, now it will be a horrible mess of 
unintelligible things with completely broken filenames
- you may not always be able to take that last look as ReactOS may lock-up 
when you open the folder in explorer (or when you hit F5 if it was already 
opened)
- in any case, ReactOS won't stay very stable for significant time 
afterwards, even if it survives the look
- if it does stay stable for a while, you won't be able to delete the 
directory nor any items in it, an attempt to delete them will fail, often 
causing a lock-up

Affected versions of Firefox
- seemingly all from the recent decade

Affected SVN builds of ReactOS
- everything from recent years as far as I can tell, but see notes below

Additional notes
- I've only tested builds made from SVN with RosBE on Windows - but many 
versions
- this bug seems to be always changing when FastFAT is touched in various 
ROS SVN builds
- about half a yer ago it was always leading to a hard lock-up and the 
filesystem was badly broken, even without opening the folder in Explorer, 
the crash would not be far away
- some 3-4 months ago, the "survival" (no-crash) rate rose somewhat, but the 
folder still got "filled" with various rubbish
- a month or 2 ago the filesystem at least tended to survive and the Firefox 
directory seemed to be "empty" after an update - although it could not be 
deleted even though nothing could be "seen" inside it, also a reinstall into 
the same folder tended to work without crashing
- in the recent 1-2 weeks one FastFAT update brought back the bad old times, 
after the failed update the Firefox directory is again getting filled with 
broken items, and the number of those items that end up in there, seems to 
have increased by a lot

Regards
Dimitrij Klingbeil