cvmfs-rust

A pure Rust implementation of the CernVM-FS client. Mount remote CVMFS repositories as local filesystems via FUSE, with full content verification and transparent decompression.

Why Rust?

The original CernVM-FS client is written in C++. This project rewrites the client in Rust to get:

• Memory safety without garbage collection
• Fearless concurrency for multi-threaded FUSE operations
• Modern tooling: cargo, clippy, built-in testing, dependency management
• Smaller binary: single static binary, no shared library dependencies beyond FUSE

Features

• FUSE filesystem mounting via fuse_mt (multi-threaded)
• Transparent zlib decompression of content-addressed objects
• RSA-PKCS1v15 signature verification of repository manifests
• SQLite catalog traversal with nested catalog support
• Chunked file reassembly for large files
• Local object caching with content-addressed storage
• HTTP/HTTPS retrieval from Stratum-1 replica servers

Quick Start

Prerequisites

• Rust (stable)
• FUSE 3 libraries:
  • macOS: macFUSE (brew install --cask macfuse)
  • Linux: sudo apt install libfuse3-dev (Debian/Ubuntu) or sudo dnf install fuse3-devel (Fedora)

Build

git clone https://github.com/moliholy/cvmfs-rust.git
cd cvmfs-rust
cargo build --release

Mount a Repository

mkdir -p /tmp/cvmfs_mount
./target/release/cvmfs-cli http://cvmfs-stratum-one.cern.ch/opt/boss /tmp/cvmfs_mount

Then browse /tmp/cvmfs_mount like any local directory. Unmount with:

# macOS
umount /tmp/cvmfs_mount

# Linux
fusermount -u /tmp/cvmfs_mount

CLI Reference

cvmfs-cli <repository_url> <mount_point> [cache_directory]

Logging

RUST_LOG=info cvmfs-cli http://cvmfs-stratum-one.cern.ch/opt/boss /tmp/cvmfs_mount

Library Usage

cvmfs-rust exposes a library crate for programmatic access:

use cvmfs::{fetcher::Fetcher, repository::Repository};

let fetcher = Fetcher::new("http://cvmfs-stratum-one.cern.ch/opt/boss", "/tmp/cache", true)?;
let mut repo = Repository::new(fetcher)?;

// List root directory
for entry in repo.list_directory("/")? {
    println!("{} ({})", entry.name, if entry.is_directory() { "dir" } else { "file" });
}

// Read a file
let mut file = repo.get_file("/testfile")?;
let mut contents = String::new();
file.read_to_string(&mut contents)?;

Development

cargo test --workspace -- --test-threads=1
cargo clippy --workspace --all-targets -- -D warnings
cargo +nightly fmt --all

License

BSD 3-Clause. See LICENSE.

Acknowledgments

• CernVM-FS (the original C++ implementation)
• CERN for maintaining public Stratum-1 servers