StuffIt (SIT, StuffIt 5)

A Go library and CLI for classic StuffIt archives:

• StuffIt 5.x (StuffIt (c)1997-... signature)
• StuffIt 5.5 and earlier classic SIT! archives
• MacBinary-wrapped .sit files
• AppleSingle-wrapped .sit files (.as / .AS)
• BinHex 4.0 (.hqx) wrappers that contain a StuffIt archive

StuffIt X (.sitx) is not supported.

Quick start

Download a tagged release for macOS or Linux (.tar.gz) or Windows (.zip), or install from source:

go install github.com/ObsoleteMadness/StuffIt-Go/cmd/stuffit@latest

stuffit list archive.sit
stuffit info archive.sit
stuffit info -json archive.sit
stuffit extract -C out archive.sit
stuffit extract -C out archive.sit "Folder/File"

Resource forks are written as AppleDouble-style sidecars named ._<filename>. Extracted names are sanitized for the host OS: Windows reserved characters and device names are replaced, while POSIX systems (including macOS HFS+/APFS) keep characters that are legal there, such as CR (\r).

info -json writes one JSON object to stdout (archive metadata plus the full catalog) so other tools can consume it.

Library

Import the package from another Go module:

go get github.com/ObsoleteMadness/StuffIt-Go/stuffit@latest

import "github.com/ObsoleteMadness/StuffIt-Go/stuffit"

Fork output hooks

The package never writes files itself. You implement data-fork and resource-fork handling independently.

Push (visitor): Extract() calls your ForkWriter:

• WriteDataFork(entry, reader)
• WriteResourceFork(entry, reader)

stuffit.Handler is a function-based adapter so you can set only the callbacks you need. A nil callback skips that fork.

Pull: iterate f.Archive.Entries and call f.OpenFork(entry.DataFork, opts) or f.OpenFork(entry.ResourceFork, opts) to stream each fork yourself.

The package does not enforce storage strategy. Consumers can map forks to:

• AppleDouble sidecar files (for example ._filename)
• Extended attributes
• Any custom metadata stream format

Compression support

• Fully supported: None, RLE, Compress (LZW), Huffman, LZAH, Fixed Huffman, MW, LZ+Huffman (dynamic and preset table modes), Installer, Arsenic

Unsupported methods are returned as explicit errors during extraction.

Usage

f, err := stuffit.Open("archive.sit")
if err != nil {
    return err
}
defer f.Close()

err = f.Extract(stuffit.Handler{
    DataFork: func(entry stuffit.Entry, r io.Reader) error {
        // persist the Macintosh data fork
        return nil
    },
    ResourceFork: func(entry stuffit.Entry, r io.Reader) error {
        // persist the Macintosh resource fork
        return nil
    },
    Directory: func(entry stuffit.Entry) error {
        return os.MkdirAll(entry.Path, 0o755)
    },
}, stuffit.ExtractOptions{})

The package never writes files itself. Implement ForkWriter (or use stuffit.Handler) to store forks however you want. To stream a single fork without a visitor, call f.OpenFork(entry.DataFork, opts) or f.OpenFork(entry.ResourceFork, opts).

Preparing a release

Releases are generated via version tags.

git tag v0.1.1
git push origin v0.1.1

Each GitHub Release includes:

• stuffit-v0.1.1-darwin-arm64.tar.gz, stuffit-v0.1.1-darwin-amd64.tar.gz
• stuffit-v0.1.1-linux-arm64.tar.gz, stuffit-v0.1.1-linux-amd64.tar.gz
• stuffit-v0.1.1-windows-arm64.zip, stuffit-v0.1.1-windows-amd64.zip
• SHA256SUMS

Every archive contains the stuffit binary, README.md, and LICENSE. Push a version tag to publish:

Credits

This library is inspired by XADMaster, MacPaw's Objective-C archive extraction library (the engine behind The Unarchiver). The classic StuffIt catalog layouts and compression methods implemented here follow that work.

The StuffIt 5 Arsenic (method 15) decoder follows Matthew T. Russotto's description of the format at http://www.russotto.net/arseniccomp.html.

Integration samples in testdata/stuffit-test-files come from Stephan Sokolow's stuffit-test-files collection of legally redistributable SIT archives. After clone, run git submodule update --init --recursive so the end-to-end tests can see them. Password-protected files in that set use password.