Project 6: Scrollback Buffer Implementation

A memory-efficient scrollback buffer that stores terminal history, supporting scrolling, search, and selection.

Quick Reference

Attribute Value
Primary Language C
Alternative Languages Rust, Zig
Difficulty Level 3: Advanced (The Engineer)
Time Estimate 2 weeks
Knowledge Area Data Structures / Memory Management
Tooling Scrollback Buffer
Prerequisites Strong understanding of pointers and memory

What You Will Build

A memory-efficient scrollback buffer that stores terminal history, supporting scrolling, search, and selection.

Why It Matters

This project builds core skills that appear repeatedly in real-world systems and tooling.

Core Challenges

  • Ring buffer design → Efficient wraparound without copying
  • Line storage → Variable-length lines with attributes
  • Memory limits → Handling millions of lines
  • Viewport management → Tracking what’s visible
  • Selection handling → Start/end coordinates across scrollback

Key Concepts

  • Ring Buffers: “Data Structures the Fun Way” Chapter 8 - Jeremy Kubica
  • Memory Management: “Computer Systems: A Programmer’s Perspective” Chapter 9 - Bryant & O’Hallaron
  • Terminal Scrollback: Alacritty’s scrollback implementation (Rust source)

Real-World Outcome

$ ./terminal_with_scrollback

# Run something that produces lots of output
$ find / 2>/dev/null
...thousands of lines...

# Now you can scroll back!
# Shift+PageUp: scroll up
# Shift+PageDown: scroll down
# Ctrl+Shift+F: search in scrollback

Search: "Documents"
Found 47 matches. Press n/N to navigate.

# Selection works across scrollback too

Implementation Guide

  1. Reproduce the simplest happy-path scenario.
  2. Build the smallest working version of the core feature.
  3. Add input validation and error handling.
  4. Add instrumentation/logging to confirm behavior.
  5. Refactor into clean modules with tests.

Milestones

  • Milestone 1: Minimal working program that runs end-to-end.
  • Milestone 2: Correct outputs for typical inputs.
  • Milestone 3: Robust handling of edge cases.
  • Milestone 4: Clean structure and documented usage.

Validation Checklist

  • Output matches the real-world outcome example
  • Handles invalid inputs safely
  • Provides clear errors and exit codes
  • Repeatable results across runs

References

  • Main guide: TERMINAL_EMULATOR_DEEP_DIVE_PROJECTS.md
  • “Data Structures the Fun Way” by Jeremy Kubica