myk@mykzilla.org wrote:

hyc@symas.com wrote on 2019-06-18 01:30:

...

There is no issue with mdb_cursor_put then. The question is why didn't mdb_page_search find the DBI's root node?

Would it be useful for mdb_cursor_init to return the result code of mdb_page_search, and for mdb_put to then return that code if it isn't MDB_SUCCESS?

Maybe. For testing purposes you could try something like this diff --git a/libraries/liblmdb/mdb.c b/libraries/liblmdb/mdb.c index 692feaa38b..e41f3bc36a 100644 --- a/libraries/liblmdb/mdb.c +++ b/libraries/liblmdb/mdb.c @@ -7620,7 +7620,8 @@ mdb_cursor_init(MDB_cursor *mc, MDB_txn *txn, MDB_dbi dbi, MDB_xcursor *mx) mc->mc_xcursor = NULL; } if (*mc->mc_dbflag & DB_STALE) { - mdb_page_search(mc, NULL, MDB_PS_ROOTONLY); + int rc = mdb_page_search(mc, NULL, MDB_PS_ROOTONLY); + mdb_cassert(mc, !rc); } }

I suspect the problem will simply be that you've used an invalid DBI.

That wouldn't resolve the problem, but it might avoid the crash and provide some insight into the failure (if mdb_page_search is actually returning a failure code when it doesn't find the DBI's root node).

-myk