dd

A Git-inspired version control system written in C++ for Linux.

dd was built from scratch to understand how modern version control systems work internally. Instead of relying on existing libraries, the project implements core concepts such as content-addressable storage, immutable objects, commit history, branching, checkout, and repository reconstruction.

Features

• Initialize and manage repositories.
• Store data using content-addressable object storage.
• Support blob, tree, and commit objects.
• Stage and track file changes through an index.
• Create commits and traverse repository history.
• Create, list, and switch between branches.
• Checkout commits or branches and reconstruct the working tree.

Example Usage

Documentation

• Architecture — Overview of the repository design, object model, and component relationships.
• Storage Format — Details of blob, tree, commit, and index storage formats.

Building

Requirements

• Linux
• CMake
• C++17 compatible compiler

Build

git clone <repository>
cd dd

mkdir build
cd build

cmake ..
cmake --build .

Usage

Initialize Repository

dd init

Stage Files

dd add file.txt

Create Commit

dd commit -m "initial commit"

View History

dd log

Create Branch

dd branch dev

List Branches

dd branch

Switch Branch

dd checkout dev

Checkout Commit

dd checkout <commit_hash>

Repository Layout

.dd/
├── objects/
│
├── refs/
│   └── heads/
│
├── HEAD
├── index
└── config

Components

Component	Purpose
objects/	Stores all immutable objects
refs/heads/	Branch references
HEAD	Current checked-out branch or commit
index	Staging area
config	Repository configuration

Key Learnings

During development, the project explored:

• Content-addressable storage
• Hash-based object databases
• Snapshot-based version control
• Commit graph traversal
• Recursive tree structures
• Filesystem manipulation
• Layered software architecture
• CLI application design
• Persistent storage systems

Future Work

Potential future extensions include:

• Diff engine
• Three-way merge
• Merge commits
• Tags
• Object compression
• Packfiles
• Remote repositories
• Push / Pull support
• Clone support
• Conflict resolution
• Detached HEAD improvements

Acknowledgements

This project was inspired by the design principles of Git and was developed as an educational exploration of version control internals and systems programming in C++.