(ITS#7834) MDB_MULTIPLE can insert multiple keys

[h.b.furuseth@usit.uio.no]

Full_Name: Hallvard B Furuseth
Version: LMDB 0.9.11
OS: Linux x86_64
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (81.191.45.35)
Submitted by: hallvard


mdb_cursor_put(,new key, multiple data items, MDB_MULTIPLE)
inserts several identical keys as well as multiple data items.

Broken since 0.9.10 by 4c8f57615c5ca7b014c038e59c1045182e74f5ad.
OpenLDAP is not affected, since it no longer uses MDB_MULTIPLE.

Root cause: mdb_cursor_put() does not reset the 'insert' flag
when looping through MDB_MULTIPLE.  Recently it uses that flag
to decode whether to delete the old key before re-inserting it.

Also MDB_MULTIPLE breaks MDB_db.md_entries so mdb_stat() reports
the wrong number of entries.  This was always so.  The 'insert'
flag also affects cursor tracking. I have not checked how.


Fix: Reset 'insert' before looping, and move setting C_INITIALIZED
at 'done:' before that again. This should make MDB_MULTIPLE behave
like a sequence of put()s, except it does not repeat spill/touch.