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.

---

Status

Release: 0.5.5 (beta)

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

Performance

v0.5.5 vs upstream rsync 3.4.1 on Linux x86_64 (110 MB, 1130 files):

Workload	oc-rsync	upstream	Speedup
Initial sync	114 ms	127 ms	1.1x
No-change sync	115 ms	131 ms	1.1x
Checksum sync (-c)	229 ms	566 ms	2.5x
Incremental (10% changed)	115 ms	129 ms	1.1x
Large files (100 MB)	89 ms	126 ms	1.4x
Small files (1000x1KB)	112 ms	129 ms	1.2x
Compressed (-z)	113 ms	127 ms	1.1x

18% faster on average; up to 2.5x faster for checksum-intensive workloads.

---

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, static musl .tar.gz
macOS (x86_64, aarch64)	.tar.gz
Windows (x86_64)	.tar.gz, .zip

Each release includes three build variants:

Variant	Description
stable (recommended)	Built with Rust stable. No filename suffix.
beta	Built with Rust beta. Filename includes -beta.
nightly	Built with Rust nightly. Filename includes -nightly.

Most users should download the stable variant.

Build from source

Requires Rust 1.88+.

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

---

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

---

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/            # Shared types, error model, config
crates/protocol/        # Wire protocol (v28-32)
crates/transfer/        # Generator, receiver, delta transfer
crates/engine/          # File list and data pump pipelines
crates/daemon/          # Daemon mode and module access control
crates/checksums/       # Rolling and strong checksums (SIMD)
crates/filters/         # Include/exclude pattern engine
crates/fast_io/         # Platform I/O (mmap, io_uring, copy_file_range)
crates/compress/        # zstd, lz4, zlib compression

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

---

Security

Protocol parsing crates enforce #![deny(unsafe_code)]. Not vulnerable to known upstream rsync CVEs (CVE-2024-12084 through CVE-2024-12088, CVE-2024-12747).

For security issues, see SECURITY.md.

---

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

---

License

GNU GPL v3.0 or later. See LICENSE.

---

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.