lmdb - Cannot create entries with long rdn

[progier389]

Issue Description
Full description in https://pagure.io/freeipa/issue/9529
Problem root cause:
An entry may have several children, so Cid key containing the reference of childrens of entry with entrid "id" has several records `. To allow that, entryrdn.db is open with MDB_DUPSORT flag. But this means that len(key) + len(data) is limited
with some hardcoded limit (i.e: 511 bytes with the current version of liblmdb)
And as the entryrdn.db data record contains both the rd and the normalized rdn the limit is reached with rdn lenght greater than about 250 bytes

Package Version and Platform:

• Platform: Fedora
• Package and version: 3.0.1

Steps to Reproduce
Steps to reproduce the behavior:

1. Through freeipa tests (See https://pagure.io/freeipa/issue/9529)
2. You can also reproduce by adding an entry with and rdn using a naming attribute with a value having 250 bytes (or more)

Expected results
A clear and concise description of what you expected to happen.

Screenshots
If applicable, add screenshots to help explain your problem.

Additional context
Jira ticket is: IDMDS-4148

[progier389]

IMHO there is a way to accept unlimited rdn (execpt for the suffix entry which will still be limited to about 480 bytes)

FYI: entryrdn data record is:
int32: EntryID
int16: rdn len
int16: nrdn len
char[rdn len] '\0' terminated rdn
char[nrdn len] '\0' terminated nrdn

The idea is to store #longdataid in the rdn
and a database @longdata.db without DUPSORT (that supports long data)
having #int16:entryrdnkeylen char[entryrdnkeylen]:entryrdnkey char[]:#longdataid --> longdata

_entryrdn_put_data
if data is too long
generate a new #longdataid (by looking at last entry in @longdata.db)
use #longdataid as rdn and nrdn for the entryrdn record
add #longdataid --> longdata record in @longdata.db

_entryrdn_del_data
if data is too long
foreach @longdata.db records starting with #entryrdnkeylen entryrdnkey
if the removed data matchs the record data
generate an rdnentry elem using #longdataid from @longdata.db records key
remove the @longdata.db record
remove the rdnentry elem record
if no match is found there is a serious error ...
else if rdn starts with #
remove #longdataid record
remove entryrdn record

_entryrdn_get_elem
if record rdn starts with #
get @longdata.db record using key: #entryrdnkeylen entryrdnkey #longdataid
use long data as entryrdn elem

_entryrdn_get_tombstone_elem
if record rdn starts with #
get @longdata.db record using key: #entryrdnkeylen entryrdnkey #longdataid
use long data as entryrdn elem

[progier389]

Issue 5105 - lmdb - Cannot create entries with long rdn - fix covscan (#6131) (BEWARE the typo in issue number)
23a094c..b295604 main -> main
99c2989..be90794 389-ds-base-3.0 -> 389-ds-base-3.0
0273672..34f8e52 389-ds-base-2.5 -> 389-ds-base-2.5

Issue 6105 - lmdb - Cannot create entries with long rdn (#6130)
d194453..b551b18 main -> main
a4e0c4a..eb8ac89 389-ds-base-2.5 -> 389-ds-base-2.5