[PATCH] minor tdb fixes

[Ralph Böhme]

On Mon, Jul 03, 2017 at 10:06:28AM +0200, Stefan Metzmacher wrote:
> > Attached is a small patchset that fixes the BUCKET() macro in tdb and the offset
> > calculations.
> > 
> > I stumpled upon this when looking at the `tdbtool DB list` output: the freelist
> > was showing the entries from another chain.
> > 
> > Turns out that the BUCKET(-1) macro returns wrong results because of sign
> > conversion, eg -1 is sign converted to an unsigned int 4294967295 and 4294967295
> > % 10 = 5. The expected result is -1, not 5.
> > 
> > This doesn't cause more severe issues because we consistenly lock the wrong
> > chain when trying to lock the freelist. It doesn't deadlock because in tdb_store
> > we lock the freelist before the hashchain. And finally in freelist.c we use the
> > FREELIST_TOP define directly, not the TDB_HASH_TOP macro that uses BUCKET.
> > 
> > Thoughts?
> 
> Sadly it's now a feature as existing tdb versions use this logic.
> So we can't just fix this as it's an incompatible change.

oh, that sucks, but you're right.

I'll prepare patches that fix `tdbtool DB list` differently and that document
the broken BUCKET macro.

Cheerio!
-slow