linked attributes, DRS and abusing the ldb modules API

[tridge at samba.org]

Hi Simo,

 > 4) instead of doing a ldb_next_request() call you do a normal
 > ldb_request() call that goes through the whole stack to perform the
 > modify operation you received.
 > 
 > If we need to skip modules in this special case we could use a control
 > to signal other modules should ignore this request. IMO this approach
 > would be a lot less problematic.

That would mean having special case code in every module, instead of
having the special case code in only one place. I think that would be
very hard to maintain.

 > Including ldb_private.h is a violation of the interface, we've gone
 > through great pains to remove any access to ldb_private.h from all code
 > except internal ldb code.

If we decide to go ahead with this module chaining approach we can
expose ldb_load_modules_list() or an equivalent function via
ldb_module.h.

For now I want to get the basic model right. For that I suspect I'm
going to need some input from Metze, as I'm not really sure exactly
what modules we do/don't want exposed to the DRS replication requests.

Cheers, Tridge