Ramjet

Ramjet is a fast, independent RAR-compatible archiver written entirely in Mach. Like its namesake engine, it compresses with nothing but speed.

The goal of Ramjet is to provide a modern, portable and fully open implementation of RAR-compatible archiving without relying on proprietary RAR/WinRAR source code.

About

Ramjet is an independent implementation focused on:

• RAR-compatible archive creation and extraction
• portability across platforms supported by Mach
• predictable and explicit systems-level code
• performance
• a clean and maintainable codebase
• fully open-source development

The project is written in Mach, a systems programming language designed around explicit control flow, explicit memory management and a small toolchain.

Independent implementation

Ramjet is an independent implementation. It does not use, include, copy or translate source code from RAR, WinRAR, UnRAR or 7-Zip's RAR code, and uses no decompiled or disassembled code. Format knowledge comes from the public RARLAB technotes, from running rar as an ordinary program and checking its output, and from reading (without copying) the BSD-licensed libarchive and LGPL-licensed XADMaster RAR readers. docs/provenance-notes.md lists the source of each piece.

Non-Goals

Ramjet is not intended to:

• reproduce or redistribute proprietary RAR/WinRAR source code
• modify or redistribute WinRAR
• provide a copy of WinRAR under an open-source license
• claim ownership of the RAR format or technology developed by its original authors

Ramjet is an independent implementation.

Status

Ramjet is being built reader first; the writer comes after the reader is complete. The aarch64 and macOS targets (darwin-x86_64 ,darwin-aarch64, linux-arm64) are built but not tested.

Reading works for RAR 5.0, RAR 2.9–4.x and RAR 2.0 archives (what RAR 2.x through 7.x create):

• listing (l, lt), testing (t), extraction (x, e) and printing (p)
• every compression method, solid archives, dictionaries up to 4 GB (RAR 5) and 4 MB (RAR 4)
• RAR 5 filters (delta, x86 E8/E8E9; ARM implemented but untested) and RAR 4 filters (delta, x86, Itanium, RGB, audio)
• RAR 4 PPMd text compression, RAR 2.0 multimedia (audio) compression
• RAR 1.5 compression is implemented but untested (no RAR 1.5 archives to test with)
• multi-volume archives (.partN.rar and .rar/.r00 naming), including split solid and encrypted sets
• encryption: AES-256 (RAR 5) and AES-128 (RAR 4), of file data and of headers, and the RAR 2.0 cipher
• CRC32 and BLAKE2sp checksums, including per-volume checksums of split files
• symbolic links, hard links, file references (-oi), file versions (-ver), SFX archives, archive comments
• file times and Unix permissions (Linux) or attributes (Windows) are restored; set-id bits never are
• builds for Linux, Windows and macOS (Windows tested under Wine)

Not yet: verified RAR 1.5 support, archives older than RAR 1.5, the RAR 7 version 1 algorithm (dictionaries over 4 GB), the writer.

See docs/provenance-notes.md for where every piece of format knowledge came from.

Building

Ramjet needs the Mach compiler (6.x).

git submodule update --init
mach build .                 # debug: out/linux-x86_64/debug/bin/ramjet
mach build . -p release      # release: out/linux-x86_64/release/bin/ramjet

Usage

ramjet <command> [switches] <archive> [files...] [@listfile] [dest/]

commands:
  l   list           lt  list with technical details     lb  bare names
  t   test           x   extract with paths               e   extract without paths
  p   print a file to stdout

switches:
  -p<password>   set the password (-p asks, -p- never asks)
  -o+ / -o- / -or   overwrite / skip / rename existing files   (-y = yes to all)
  -x<mask>       exclude files (repeatable, -x@<file> for a list)
  -op<path>      extract into this directory      -ad  into a folder named after the archive
  -kb            keep files that failed their checksum
  -ver           also extract older file versions as name;N
  -idq / -inul   quiet / silent                    -idp  no progress display

Switches can go anywhere on the line (until --). A last argument ending in / is the destination; other arguments select files by name or */? mask, and a directory name selects everything under it.

On a terminal Ramjet asks for missing passwords (input is not echoed) and asks before overwriting files; without one it never waits for input and keeps existing files. Large files show a progress percentage.

Exit status: 0 ok, 1 warning, 2 fatal error, 3 damaged data, 5 write error, 6 open error, 7 bad command line, 8 out of memory, 9 cannot create a file, 10 no files matched, 11 wrong or missing password, 255 stopped.

Extraction never writes outside the destination: names with .. are refused, absolute names are made relative, symbolic links are created only after all files are written, and on Windows backslashes, drive letters, trailing dots and device names (CON, NUL, ...) are neutralized too.

Testing

The sample archives are not part of the repository: they are made on your machine by the archivers themselves (RAR 7.x, RAR 4.20 and RAR 2.50, run as ordinary programs), so first run the generators below.

mach test .                          unit tests
tests/gen_samples.sh                 rebuild the RAR 5 samples (needs the rar tool)
tests/get_rar4.sh                    download RAR 4.20 (git-ignored) for the RAR 4 samples
tests/gen_samples_rar4.sh            rebuild the RAR 4 samples
tests/gen_samples_rar2.sh            rebuild the RAR 2.0 samples (needs rar250.exe and dosbox)
tests/gen_samples_rar3.sh            rebuild the RAR 3.x encryption samples (downloads pinned RAR 3.x packages)
tests/check_extract.sh               extract every sample and compare with its source files
tests/check_cli.sh                   command-line behavior and exit codes
tests/compare_list.py [bin] [dir]    compare `ramjet lt` with `rar lt` (dir: tests/samples/rar4 for RAR 4)
tests/fuzz.py 1000                   corrupted archives must never crash ramjet

Releases

The version lives in mach.toml (ramjet --version reads it at build time) and follows semantic versioning. A release is:

1. bump version in mach.toml and add a section to CHANGELOG.md
2. commit, then tag it: git tag -a vX.Y.Z -m "Ramjet X.Y.Z"
3. git push origin main vX.Y.Z
4. build mach build . -t <target> -p release for each target and attach the binaries to a GitHub release for the tag

Another Mach project can depend on a release with ref = "tag/vX.Y.Z".

Contributing

Contributions are welcome.

Before contributing code, please make sure that your contribution does not contain:

• proprietary RAR/WinRAR/UnRAR source code
• code copied from proprietary implementations
• decompiled or disassembled proprietary code
• confidential or non-public implementation information

When adding a new feature, prefer:

• independently written code
• documented behavioral observations
• reproducible tests
• clear technical reasoning
• references to publicly available specifications where applicable

Licensing

Ramjet is licensed under the GNU General Public License v3.0 (GPL-3.0).

See LICENSE for the complete license text. Binaries include the Mach standard library (MIT); see THIRD_PARTY_NOTICES.txt.

This license applies to the original Ramjet source code.

Disclaimer

Ramjet is an independent open-source project.

Ramjet is not affiliated with, endorsed by, or sponsored by RARLAB, win.rar GmbH, Alexander Roshal, or the WinRAR project.

RAR and WinRAR are trademarks and/or products associated with their respective owners.

This project does not distribute WinRAR or proprietary RAR source code.