rit

rit is a Git re-implementation from scartch in Rust.

The goal of this project is to learn how Git works internally by rebuilding its core concepts step by step: object storage, hashing, trees, commits, references, branches, the index, checkout, status, and diff. It follows the git source code mirror implemented originally in C at Original C source code mirror

Current Features Implemented + more to add

• Initialize a repository with .rit
• Store Git-style objects using SHA-1 and zlib compression
• Support blob, tree, and commit objects
• Hash files into the object database
• Read and pretty-print objects
• Write recursive tree snapshots
• Create commits from the staging area
• Maintain HEAD and branch references
• View commit history with log
• Stage files with add
• Show working tree state with status
• Switch branches and restore commits with checkout
• Protect checkout from overwriting uncommitted changes
• Remove tracked files during checkout when switching branches
• Show unstaged changes with diff
• Show staged changes with diff --cached

Commands

rit init
rit add <file>
rit commit -m "message"
rit status
rit diff
rit diff --cached
rit log
rit branch
rit branch <name>
rit checkout <branch-or-commit>
rit hash-object <file>
rit cat-file <hash>
rit write-tree

Repository Structure

A rit repository stores its data in .rit:

.rit/
├── HEAD
├── config
├── index
├── objects/
└── refs/
    └── heads/

Core Concepts

rit follows the same core model as Git:

working tree
    ↓ rit add
index
    ↓ rit commit
commit
    ↓
tree
    ↓
blobs

Objects are stored by content hash:

content -> SHA-1 hash -> compressed object file

Branches are simple files under:

.rit/refs/heads/

HEAD points to the currently active branch.

Example Usage

rit init

echo "hello" > hello.txt
rit add hello.txt
rit commit -m "initial commit"

echo "second line" >> hello.txt
rit status
rit diff

rit add hello.txt
rit diff --cached
rit commit -m "update hello"

rit branch feature
rit checkout feature

Development

Build the project:

cargo build

Run a command during development:

cargo run -- status

Run the compiled binary:

target/debug/rit status

Current Limitations

• The index uses a simple JSON format, not Git’s binary index format.
• Diff is a basic line-by-line implementation, not a full Myers diff.
• Remote operations such as clone, fetch, and push are not implemented yet.
• Merge support is not implemented yet.
• Checkout protection is conservative and blocks all untracked files.