AnyFS Ecosystem

An open standard for pluggable virtual filesystem backends in Rust.

Overview

AnyFS is an open standard for virtual filesystem backends using a Tower-style middleware pattern for composable functionality.

You get:

• A familiar std::fs-aligned API
• Composable middleware (limits, logging, security)
• Choice of storage: memory, SQLite, host filesystem, or custom
• A developer-first goal: make storage composition easy, safe, and enjoyable

Architecture

┌─────────────────────────────────────────┐
│  FileStorage<B>                         │  ← Ergonomic std::fs-aligned API
├─────────────────────────────────────────┤
│  Middleware (composable):               │
│    Quota<B>                             │  ← Quotas
│    Restrictions<B>                      │  ← Security
│    Tracing<B>                           │  ← Audit
├─────────────────────────────────────────┤
│  Fs                                     │  ← Storage
│  (Memory, SQLite, VRootFs, custom...)   │
└─────────────────────────────────────────┘

Each layer has one job. Compose only what you need.

Two-Crate Structure

Note: Mounting (FsFuse + MountHandle) is part of the anyfs crate behind feature flags (fuse, winfsp), not a separate crate.

Quick Example

#![allow(unused)]
fn main() {
use anyfs::{MemoryBackend, QuotaLayer, RestrictionsLayer, FileStorage};

// Layer-based composition
let backend = MemoryBackend::new()
    .layer(QuotaLayer::builder()
        .max_total_size(100 * 1024 * 1024)
        .build())
    .layer(RestrictionsLayer::builder()
        .deny_permissions()
        .build());

let fs = FileStorage::new(backend);

fs.create_dir_all("/data")?;
fs.write("/data/file.txt", b"hello")?;
}

How to Use This Manual

Future Considerations

These are optional extensions that fit the design but are out of scope for initial release:

• URL-based backend registry and bulk helpers (FsExt/utilities)
• Async adapter for remote backends
• Companion shell for interactive exploration
• Copy-on-write overlay and archive backends (zip/tar)

See Design Overview for the full list and rationale.

Status

Authoritative Documents

1. AGENTS.md (for AI assistants)
2. src/architecture/design-overview.md
3. src/architecture/adrs.md