bitcoinleveldb-posixmmaprfile vs bitcoinleveldb-env vs bitcoinleveldb-posixtools

POSIX mmap(2)-backed implementation of a LevelDB-style RandomAccessFile for read-only random file access with explicit mmap limiting and deterministic resource teardown.

Rust implementation of LevelDB's Env abstraction for the bitcoinleveldb port, providing environment traits, delegating wrappers, file utilities, and logging helpers closely matching the original C++ API.

POSIX-focused LevelDB support utilities: singleton environment wiring, mmap and open-file limit management, process-local POSIX file-lock tracking, and errno-to-Status translation for Bitcoin-leveldb integrations.