Howard Chu authored Jan 12, 2014 and Quanah Gibson-Mount committed Jan 13, 2014

free(NULL) is supposed to be safe. "Portable wrapper libraries"
that fail to preserve this behavior are inherently broken.
But then again, this is Mozilla code, so that's redundant.

db_mid2l_insert(): Move assert to mdb.c.
mdb_cursor_set(): Previous assert cannot fail now.
mdb_cursor_put(): Check mc/key and return EINVAL.
mdb_cursor_dbi(): No error return, so just segfault if cursor==NULL.

This should likely be reverted when all callers handle these errors.

mdb_cursor_put(): Use free sub-page space added by a
previous put(existing DUPSORT item), if any.
Tweak NUMKEYS code to avoid a new signedness warning.

It was inaccurate and misplaced. Verify it in mdb.c instead.

I.e. d69d2ce2, it left out some changes.

It and the MDB_msg_func can now return >= 0 for success.
Always return any MDB_msg_func() error result.

Use a sub-DB for DUPSORT item #1/#2 per key if needed: Not a sub-
page too big for a node, nor an overflow page (which not all DUPSORT
code checks for). Move "insert" code, to avoid non-loop goto upwards.

(This is the commit which needs the change to xdata.mv_size in
commit 9d6e4a91 "page sizes".)

Handle keys stored by a liblmdb with a bigger MDB_MAXKEYSIZE.
mdb_get/mdb_del(absent key bigger than our MDB_MAXKEYSIZE)
now return MDB_NOTFOUND instead of MDB_BAD_VALSIZE.