rars

A Rust implementation of RAR.

Current Status

rars covers the RAR lineage from early RE~^ archives through RAR 7, compression and decompression. It's getting faster, and kinda works.

Rust API

Use the rars crate for Rust applications and libraries. Since 0.4, the lower-level rars-format, rars-codec, rars-crypto, rars-crc32, and rars-recovery crates are folded into rars; those standalone crates ended at 0.3.x. Applications should depend on rars, and command-line installs should use rars-cli.

CLI

Inspect, test, and extract archives:

rars info archive.rar
rars test archive.rar
rars x archive.rar out/

Create archives with specific RAR generation:

rars a --format rar29 archive.rar files...
rars a --format rar50 --solid --auto-filter archive.rar files...
rars a --format rar70 --store --volume-size 10m archive.part1.rar files...

The writer supports stored and compressed members, split volumes, passwords, header encryption where implemented, comments, RARVM filters, RAR5 quick-open records, and supported recovery records. Run rars --help for the exact option set.

Non-solid RAR 5 and RAR 7 creation streams path inputs through bounded codec windows and disk-backed payload spools. The global compression workspace limit defaults to 256 MiB and is shared by Rayon jobs; a dictionary that cannot fit is rejected before compression starts. Temporary payloads are created beside the output archive by default.

rars a --memory-limit 128m --temp-dir /path/with/space archive.rar files...

Parallel work

Rayon worker threads process independent archive members. This parallelizes non-solid compression planning for supported writers and buffered extraction of non-solid, non-split single archives while preserving archive order for output. Solid archives and multivolume extraction fall back to the existing sequential stream because their codec state depends on member order.

Control the number of workers with --threads:

cargo run -p rars-cli -- --threads 4 a --format rar50 archive.rar files...
cargo run -p rars-cli -- x --threads 4 archive.rar out/

Measure parallel archive-member work with Criterion:

cargo bench -p rars --bench parallel

The parallel benchmark reports 1_thread and all_threads_N cases for RAR5 multi-member compression and extraction.

When --threads is omitted, rars uses all available cores. Pass --threads 1 to run member work serially.

Python bindings

The workspace includes PyO3 bindings packaged as the rars Python module for Python 3.10 and newer. Independent archive members are processed in parallel.

maturin develop

The Python API exposes a rarfile-style RarFile for listing, reading, testing, and extracting archives, plus RarBuilder for creating or rewriting archives. Rewrites are staged into a new archive; existing RAR files are not edited in place. RarBuilder.add() keeps path inputs lazy, and the common non-solid RAR 5/7 write() path writes directly instead of first constructing the complete archive in memory. add_bytes() and to_bytes() remain available as convenience wrappers.

Development

Run the test suite:

cargo test --workspace --all-targets

Generate a local coverage report:

rustup component add llvm-tools-preview
./scripts/coverage.py

The script prints a line-coverage summary, saves it to target/coverage/summary.txt, and writes HTML output to target/coverage/html/library/index.html and target/coverage/html/cli/index.html.