LimniFS

Layered, Immutable, Merkle-rooted, Network Image filesystem.

LimniFS is a content-addressed, compressed, immutable filesystem image format for archival, distribution, and cold storage. It packs directory trees into a single .lim file with BLAKE3 content addressing, per-content-class compression, and Merkle-rooted integrity.

Quick start

# Build
cargo build --release

# Create an image from a directory
./target/release/limni limn my-project/ my-project.lim

# Verify integrity
./target/release/limni verify my-project.lim

# List contents
./target/release/limni ls my-project.lim

# Extract
./target/release/limni extract my-project.lim output/

# Mount (requires FUSE; Linux/macOS)
./target/release/limni --features fuse mount my-project.lim /mnt/limnifs

Features

• Content-addressed. Every drop's identity is BLAKE3(plaintext). Codec, encryption, and erasure coding are representations, never identity.
• Per-content-class compression. The seine classifier routes each chunk to the best codec: ZSTD for text, LZ4 for binary, store for incompressible data.
• Merkle-rooted integrity. The manifest root commits to the entire image. One signature verifies everything.
• Pure Rust. No C dependencies. Air-gapped safe. #![forbid(unsafe_code)].
• Parallel. The writer uses rayon for parallel chunking, hashing, and compression.
• Six codecs. Store, LZ4, ZSTD, Brotli, DEFLATE, Snappy — all pure Rust, all behind an OCP codec registry.
• Optional crypto. XChaCha20-Poly1305 AEAD, HPKE key wrap, Ed25519 signing, Shamir k-of-n secret sharing — each behind a feature flag.
• Erasure coding. Reed-Solomon systematic Vandermonde for per-slab redundancy and offline repair.
• Remote locators. HTTP range streaming, S3, IPFS/CAR — slabs can live anywhere.
• FUSE mount. Read-only mount on Linux and macOS.

Codec portfolio

Id	Codec	Encode	Decode	Pure Rust
0x00	store	yes	yes	yes
0x01	LZ4	yes	yes	yes (lz4_flex)
0x02	ZSTD	yes (L1)	yes	yes (ruzstd)
0x03	XZ/LZMA2	no	yes	yes (omnizip-lzma)
0x04	Brotli	yes (q11)	yes	yes (brotli)
0x05	DEFLATE	yes (L6)	yes	yes (miniz_oxide)
0x06	Snappy	yes	yes	yes (omnizip-snappy → snap)

Adding a codec is one new file + one register() call — the dispatch code never changes (open/closed via [CodecRegistry]).

Performance

Benchmarked against DwarFS 0.15.6 on a 440 MB text corpus:

Operation	LimniFS	DwarFS	Ratio
Create	0.62s (700 MB/s)	1.00s	1.6x faster
Extract	0.59s (8500 files/s)	1.37s	2.3x faster
Image size	8% smaller	baseline	—

Crate structure

Crate	Description
[limnifs-format]	Wire-format primitives (header, cursor, version constants)
[limnifs-core]	Manifest parser, drop store, codec registry, crypto, locators
[limnifs-write]	Writer pipeline (FastCDC, classifier, slab packing, deepening)
[limnifs-conformance]	Test vectors and differential harness
[limni]	The limni CLI binary

Feature flags

Flag	Adds	Air-gapped safe?
(default)	BLAKE3, LZ4, ZSTD, Brotli, DEFLATE, Snappy, Ed25519	yes
http	HTTP/S3/IPFS locators	network required
fuse	FUSE mount	system FUSE required
key-wrap	HPKE X25519 key wrap	yes
signing	Ed25519 manifest signing	yes

Installation

From source

git clone https://github.com/limnifs/limnifs.git
cd limnifs
cargo build --release
# Binary: target/release/limni

From crates.io (library use)

[dependencies]
limnifs-core = "0.1"

License

Apache-2.0 OR MIT.

Links

• Format specification
• Python reference reader
• Website
• omnizip-rs — pure-Rust codec ports