Deleting overlays from cn=config

[Ralf Haferkamp <rhafer@suse.de>]

Hi,

as back-config does currently not have support for the delete operation 
(config_back_delete() just returns  LDAP_UNWILLING_TO_PERFORM 
currently) I am trying to figure out what is needed to get at 
least delete support for simple overlays (e.g. ppolicy or memberof) 
running.

What I am currently doing is:
- renumber the indexes of the siblings of the overlay that's going to be 
deleted
- remove the CfEntryInfo of the overlay from the internal config tree
- remove the Entry from the underlying LDIF database

Additionally I need to remove the overlay's slap_overinst structure from 
the overlay list of the backend and in case it was the last overlay, 
restore the original BackendInfo structure and delete the 
SLAP_DBFLAG_GLOBAL_OVERLAY flag from the BackendDB structure of the 
underlying database (for global overlays). Currently I use the 
overlay_destroy_one() function for this task. This also calls the 
db_destroy() hook of the overlay which should take are of free 
resources held by the overlay.

I am a bit unsure about the db_destroy() part. Is that enough or is it 
needed to call the db_close() hooks (when provided by the overlay) 
before calling db_destroy()? Did I miss something else? Is anybody else 
currently working on this?

Up to now I am testing this only with some simpler overlays (memberof, 
pcache), I assume that deleting overlays that instantiate their own 
databases (like pcache, translucent(?)) might get a little more hairy.

-- 
Ralf