MiniLibC

Table of Contents

• Overview
• Goals
• Features
  • Required Functions
  • Bonus Functions
• Compilation & Usage
• Contributing
• License

Overview

MiniLibC is a minimalistic C-runtime library built from scratch in x86-64 NASM assembly. It allows you to replace—or override—standard libc functions via dynamic linking (LD_PRELOAD), offering insights into low-level implementations and performance characteristics.

Goals

• Educational: Deepen understanding of common libc routines by reimplementing them in assembly.
• Portable: Produce a standalone dynamic ELF library (libasm.so) compatible with x86-64 Linux.
• Lightweight: Focus on clarity and minimal dependencies, avoiding any external C runtime requirements.

Features

Required Functions

• strlen
• strchr
• strrchr
• memset
• memcpy
• strcmp
• memmove
• strncmp
• strcasecmp
• strstr
• strpbrk
• strcspn

Bonus Functions

• All the library handle in 32 bits
• index / rindex

Feel free to extend with your own additional routines (e.g., strtok, printf), architectures (ARM, RISC-V), or other creative enhancements.

Compilation & Usage

1. Clone the repository

   git clone https://github.com/yourusername/minilibc.git
   cd minilibc

2. Build

   make        # Assemble all .asm files and link into libasm.so
   make re     # Rebuild from scratch (clean + build)
   make clean  # Remove object files and temporary artifacts
   make fclean # Remove everything including libasm.so

3. Test / Run Use LD_PRELOAD to override libc functions:

   LD_PRELOAD=$(pwd)/libasm.so ./your_program

Contributing

Contributions, issues, and feature requests are welcome!

1. Fork the repository.
2. Create your feature branch (git checkout -b feature/foo).
3. Commit your changes (git commit -am 'Add foo feature').
4. Push to the branch (git push origin feature/foo).
5. Open a Pull Request.

Please stick to NASM syntax for new assembly routines and include tests where applicable.

License

This project is licensed under the MIT License. See the LICENSE file for details.