Multiple code paths don't check InDomain() before using prefix extractor

[yiwu-arbug]

DBIter and HashSkipListRep don't check InDomain() before using prefix extractor, which can cause crash or unexpected behavior.

rocksdb/db/db_iter.cc

Line 465 in 29111e9

prefix_extractor_->Transform(ikey_.user_key)

rocksdb/memtable/hash_skiplist_rep.cc

Line 182 in 29111e9

auto transformed = memtable_rep_.transform_->Transform(ExtractUserKey(k));

Expected behavior

RocksDB either correctly handle keys out of domain of prefix extractor, or return error.

Actual behavior

RocksDB may crash.

Steps to reproduce the behavior

Insert keys not satisfying prefix extractor to the DB.

[anand1976]

@yiwu-arbug Thanks for reporting. It looks like there are more places where Transform() is called without calling InDomain() first - HashLinkListRep, SkipListRep, PlainTable, and ForwardIterator.