mem-fs

A minimal, deterministic in-memory file system for embedded and systems projects.

mem-fs is a lightweight, high-performance in-memory file system written in Rust. It is designed for environments where predictable memory usage, fast access, and tight control over allocation matter more than complex storage semantics.

Typical use-cases include:

• embedded systems & firmware
• robotics runtimes
• game engines and simulation tooling
• small experimental “OS” or application platforms

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✨ Goals

mem-fs focuses on predictable memory usage and simple in-memory storage, rather than full persistent filesystem semantics.

mem-fs aims to provide a tiny, self-contained file system abstraction that can:

• Store files directly in memory (RAM or a user-provided buffer)
• Work in no_std environments
• Avoid dynamic allocation where possible
• Provide deterministic, inspectable memory layout
• Be embedded into a larger runtime (asset system, scripting VM, firmware storage, etc.)
• Optionally support dumping/loading its state for persistence

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🚫 Non-goals

This crate intentionally does not aim to be:

• POSIX compliant
• a replacement for persistent filesystems (FAT, LittleFS, ext4, …)
• feature-rich in permissions, users, or security models
• crash-safe or journaling (at least not in early versions)

mem-fs is about control, simplicity, and predictability, not completeness.

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🧪 Status

mem-fs is experimental and under active development.

• APIs may change.
• Internal layout and structures are still evolving.
• The crate is primarily developed as part of a larger embedded “pocket-computer” project.

That said, the project builds cleanly and is meant to grow into a solid, reusable component.

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📦 Example

use mem_fs::MemFs;

let mut fs = MemFs::new();

fs.create("hello.txt", b"Hello mem-fs!").unwrap();
fs.append("hello.txt", b" Pretty cool!").unwrap();

let data = fs.read("hello.txt").unwrap();