Implementing a Backend

This tutorial walks you through implementing a complete filesystem backend from scratch. By the end, you’ll have a working in-memory filesystem that implements all traits up to FsPosix.

What You’ll Build

An in-memory filesystem (TutorialFs) that:

• Stores files and directories in memory
• Supports symlinks
• Tracks permissions and timestamps
• Provides inode-based access for FUSE
• Implements file handles and locking

Prerequisites

• Basic Rust knowledge (structs, traits, Result)
• Understanding of filesystem concepts (files, directories, symlinks)

Tutorial Structure

Each chapter introduces one or more traits:

1. Core Data Structures - Design the internal state
2. FsRead - Read files and metadata
3. FsWrite - Write and delete files
4. FsDir - Directory operations
5. The Fs Trait - Combining the basics
6. FsLink - Symlink support
7. FsFull - Permissions, sync, stats
8. FsInode - FUSE inode operations
9. FsPosix - Handles and locking

Running the Examples

Each chapter has runnable example code. Clone the repository and run:

cargo run --example tutorial_backend_complete

The End Result

After completing this tutorial, you’ll understand:

• How each trait fits into the hierarchy
• What each method should do and return
• Error handling conventions
• Thread-safety requirements
• How blanket implementations work

Let’s start with Core Data Structures →