[Haiku-commits] r30960 - haiku/trunk/src/system/kernel/cache

[Stephan Aßmus]

Rene Gollent schrieb:
> On Fri, Jun 5, 2009 at 7:03 AM, Stephan Aßmus<superstippi at gmx.de> wrote:
>> So when I just move mails from one mail folder into the Trash, could
>> that cause that folder to be "truncated" so that it could mess up data
>> from another folder? Other than that, I don't see a "truncation"
>> operation being involved at all in what I do to trigger the bug that
>> mails disappear from one of my mail folders, so it's probably unrelated,
>> correct?
> 
> Most likely unrelated. This particular bug as I understand it would
> essentially be triggered as follows: Some file gets truncated to 0
> bytes, and its storage is thus freed. Something else then winds up
> getting allocated on the disk in the same spot where those file blocks
> used to be, say, a B+ tree. Then due to the bug, the same blocks where
> that directory was just written to get overwritten with some other
> blocks. Presto, corrupted B+ tree. Requires a pretty specific set of
> circumstances to trigger though, which sound completely different from
> your disappearing email. Correct me if I'm wrong Axel :)

So what happened if a program overwrites some file's contents, even if 
they end up being the same size or larger than before? Wouldn't that too 
start with a truncate operation depending on how you do it? What about 
attributes, were those affected in the same way? I don't really know if 
anything that Beam does could fit the situation. I guess I will simply 
find out when I use Beam more frequently on that machine again... :-)

Best regards,
-Stephan