oc-rsync

rsync re-implemented in Rust. Wire-compatible with upstream rsync 3.4.1 (protocol 32), works as a drop-in replacement.

Binary name: oc-rsync — installs alongside system rsync without conflict.

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Status

Release: 0.5.8 (beta)

Core transfer, delta algorithm, daemon mode, and SSH transport are complete. Interoperability tested against upstream rsync 3.0.9, 3.1.3, and 3.4.1.

Performance

Threaded architecture replaces upstream's fork-based pipeline for local transfers, reducing syscall overhead and context switches.

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Installation

Homebrew

brew tap oferchen/rsync https://github.com/oferchen/rsync
brew install oferchen/rsync/oc-rsync

Prebuilt packages

Download from the Releases page:

Platform	Formats
Linux (x86_64, aarch64)	.deb, .rpm (with OpenSSL), static musl .tar.gz
macOS (x86_64, aarch64)	.tar.gz
Windows (x86_64)	.tar.gz, .zip

Linux static tarballs are available in two checksum variants:

Variant	Filename	Description
Pure Rust (recommended)	*-musl.tar.gz	Pure-Rust checksums, zero system dependencies
OpenSSL	*-musl-openssl.tar.gz	OpenSSL-accelerated MD4/MD5 checksums (vendored, statically linked)

Each release also includes three toolchain variants: stable (recommended, no suffix), beta (-beta), and nightly (-nightly).

Build from source

Requires Rust 1.88+.

git clone https://github.com/oferchen/rsync.git
cd rsync
cargo build --workspace --release

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Usage

Works like rsync:

# Local sync
oc-rsync -av ./source/ ./dest/

# Remote pull
oc-rsync -av user@host:/remote/path/ ./local/

# Remote push
oc-rsync -av ./local/ user@host:/remote/path/

# Daemon mode
oc-rsync --daemon --config=/etc/oc-rsyncd/oc-rsyncd.conf

For supported options: oc-rsync --help

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Development

Prerequisites

• Rust 1.88.0 (managed via rust-toolchain.toml)
• cargo-nextest: cargo install cargo-nextest --locked

Build and test

cargo fmt --all -- --check
cargo clippy --workspace --all-targets --all-features --no-deps -D warnings
cargo nextest run --workspace --all-features

Project layout

src/bin/oc-rsync.rs     # Entry point
crates/cli/             # CLI flags, help, output formatting
crates/core/            # Orchestration facade, session management, config
crates/protocol/        # Wire protocol (v28-32), multiplex framing
crates/transfer/        # Generator (sender), receiver, delta transfer
crates/engine/          # Local copy executor, sparse writes, temp-file commit
crates/daemon/          # Daemon mode, module access control, systemd
crates/checksums/       # Rolling and strong checksums (MD4, MD5, XXH3, SIMD)
crates/filters/         # Include/exclude pattern engine, .rsync-filter
crates/metadata/        # Permissions, uid/gid, mtime, ACLs, xattrs
crates/rsync_io/        # SSH stdio, rsync:// TCP transport, handshake
crates/fast_io/         # Platform I/O (io_uring, copy_file_range, sendfile)
crates/compress/        # zstd, lz4, zlib compression codecs
crates/bandwidth/       # Bandwidth limiting and rate control
crates/signature/       # Signature layout and block-size calculations
crates/match/           # Delta matching and block search
crates/flist/           # File list generation and traversal
crates/logging/         # Logging macros and verbosity control
crates/logging-sink/    # Message sink and output formatting
crates/batch/           # Batch file read/write support
crates/branding/        # Binary naming and version metadata
crates/embedding/       # Programmatic entry points for library usage
crates/apple-fs/        # macOS filesystem operations (clonefile, FSEvents)
crates/windows-gnu-eh/  # Windows GNU exception handling shims

See cargo doc --workspace --no-deps --open for API documentation.

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Security

Protocol parsing crates enforce #![deny(unsafe_code)]. Unsafe code is limited to:

• SIMD-accelerated checksums (with scalar fallbacks)
• Platform I/O operations (sendfile, io_uring, mmap -- with fallbacks)
• Metadata/ownership FFI (UID/GID lookup, chroot, setuid/setgid)
• Windows GNU exception handling

Not vulnerable to known upstream rsync CVEs (CVE-2024-12084 through CVE-2024-12088, CVE-2024-12747). OS-level race conditions (TOCTOU) remain possible at filesystem boundaries.

For security issues, see SECURITY.md.

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Contributing

1. Fork and create a feature branch
2. Run cargo fmt, cargo clippy, and cargo nextest run
3. Open a PR describing behavioral changes and interop impact

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License

GNU GPL v3.0 or later. See LICENSE.

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Acknowledgements

Inspired by rsync by Andrew Tridgell and the Samba team. Thanks to Pieter for his heroic patience in enduring months of my rsync commentary.