(ITS#6837) slapd doesn't start anymore after adding olcChainDatabase

[rhafer@suse.de]

Full_Name: Ralf Haferkamp
Version: RE24, HEAD
OS: 
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (89.166.243.151)


After adding the following LDIF to cn=config (via ldapadd), slapd does not start
anymore:
------------------------------------
dn: olcOverlay={0}chain,olcDatabase={-1}frontend,cn=config
objectclass: olcChainConfig

dn: olcDatabase={0}ldap,olcOverlay={0}chain,olcDatabase={-1}frontend,cn=config
objectclass: olcLDAPConfig
objectclass: olcChainDatabase
olcDbUri: ldap://ldap.server
olcDatbase: {0}ldap
------------------------------------

To add some fun. Everything works as expected if I reorder the "objectClass"
Values so that "olcLDAPConfig" appears after "olcChainDatabase".

Additionally the error messages I get in the log when slapd fails to start with
the above config seem to be completely unrelated:
------
olcRootPW: value #0: <olcRootPW> can only be set when rootdn is under suffix
config error processing olcDatabase={0}config,cn=config: <olcRootPW> can only be
set when rootdn is under suffix
------

The underlying problem seems to be that, when the "olcLDAPConfig" objectclass
appears first slapd seems to choose the wrong ConfigTable for the olcDatabase
attribute of the olcChainDatabase object. Instead of using olcDatabaseDummy as
defined in back-ldap/chain.c it uses the "normal" ConfigTable and starts up the
LDAP Database as if it were in "normal" database, including adding it to the
backendDB list. As I configured the chain overlay as a global overlay this
back-ldap database is put to the front of the backendDB list leading to problems
when initializing the cn=config database itself, because the code assumes that
the config database is always the first one, which will than lead to the strange
error message above.

(... that's how far I got with analyzing the problem, I have no idea yet how to
fix it though. Suggestions are welcome.)