The Art of Debugging: Debugger Internals

Ever wondered how to develop a Go debugger? Curious about how debuggers work under the hood? This book provides comprehensive insights into these topics. Read the Chinese version online at: https://www.hitzhangjie.pro/debugger101.io/

English version available at: https://www.hitzhangjie.pro/debugger101-en.io/ And the repo: https://github.com/hitzhangjie/golang-debugger-book-en .

Introduction

This project delves into the development of a Go debugger, exploring various aspects including:

• Operating System support mechanisms
• Coordination between compiler, linker, and debugger
• Debugging information standards
• How to develop an instruction level debugger
• How to develop an symbolic level debugger
• How does the mordern debugger architect looks like
• How do to debug in modern software development
• And much more

Special thanks to delve and its author derek parker, contributor aarzilli, along with all contributors. Their work has been instrumental in my learning journey, and I'm excited to share this knowledge with developers interested in debugging.

Developing a symbolic debugger requires a deep understanding of:

• Operating Systems (e.g., Linux ptrace and OS scheduler)
• CPU semantics, instructions (e.g., instruction patching), hardware breakpoints register, eflags
• Compilers, linkers, and loaders, and the debugger? How do they work together to help debugging
• Executable file formats and debugging information storage
• The description of different languages features, data, types on different OS, Archs
• Programming language-specific features (e.g., goroutines)

This project serves as an excellent opportunity to enhance your understanding of computer systems and their underlying technologies.

Sample Code

The project includes a companion repository "golang-debugger-lessons" containing sample code that corresponds to each chapter. The "0-godbg" directory provides a complete implementation of a insctruction-level debugger for Go."tinydbg" repository is a go-delve/delve fork and simplified version for Linux/Amd64 to help you quickly understand the core concepts and code.

While established debuggers like GDB and Delve exist for Go, developing a debugger from scratch serves as an excellent learning exercise. It not only helps understand how the debugger works, but also helps integrate knowledge across various domains:

• Go language internals (type system, goroutine scheduling)
• Go commandline utities development, especially uses spf13/cobra
• System level programming, understand how build toolchain works, how kernel works, how CPU works
• Go ebpf tracing utilities programming
• Operating system kernel concepts (virtual memory, task scheduling, system calls, instruction patching)
• etc.

Perhaps more than understanding how debuggers work, deepening my knowledge of Computer Systems was the fundamental motivation behind writing this book. And, I wish this book could help more readers, too.

Reading Locally

The book follows GitBook's structure, but since gitbook-cli is deprecated, we offer two methods to read the book locally:

Using Docker (Recommended)

# For English version
rm book/_book
docker run --name gitbook --rm -v ${PWD}/book:/root/gitbook hitzhangjie/gitbook-cli:latest gitbook install .
docker run --name gitbook --rm -v ${PWD}/book:/root/gitbook -p 4000:4000 -p 35729:35729 hitzhangjie/gitbook-cli:latest gitbook serve .

For convenience, these commands are available in the Makefile - simply run make english to start the server.

Using Legacy gitbook-cli

1. Clone the repository:

git clone https://github.com/hitzhangjie/golang-debugger-book-en

2. Serve the book:

cd book
gitbook install && gitbook serve

Note: Installing gitbook-cli directly may encounter compatibility issues with recent Node.js and graceful-fs versions. To avoid these issues, we recommend using our Docker image hitzhangjie/gitbook-cli:latest instead of npm or homebrew installation.

Contact

For any questions or feedback, please email me at [email protected]. I'll respond as soon as possible.

License

<a rel="license" href="http://creativecommons.org/licenses/by-nd/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-nd/4.0/88x31.png" />``</a><br />This work is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-nd/4.0/">Creative Commons Attribution-NoDerivatives 4.0 International License </a>.