libnar

Library for reading and writing from NAR (Nix Archive) files written in Rust.

The NAR format, developed exclusively for the Nix package manager, is a fully deterministic and reproducible alternative to the tar archive format. It is used to serialize and deserialize filesystem objects, such as files and directories and symlinks, in and out of the Nix store. Unlike tar, .nar archives have the following properties:

1. Deterministic ordering when unpacking files
2. Fully specified, no undefined or implementation-specific behavior
3. Strips out non-reproducible file metadata (creation time, last access time, owner and group IDs, all file mode permissions except for executable) before packing and normalizes them at unpacking time
4. Strips out the setuid and sticky bits along with all filesystem-specific extended attributes before packing

libnar is a fast and lightweight implementation of the Nix Archive format in Rust and provides a convenient interface for opening, creating, packing, and unpacking .nar files. It is intentionally kept as minimal as possible with few dependencies to keep the codebase portable.

Examples

Opening an archive

use std::fs::File;

use libnar::Archive;

fn main() {
    let file = File::open("/path/to/archive.nar").unwrap();
    let mut nar = Archive::new(file).unwrap();

    let entries = nar.entries().unwrap();
    for entry in entries {
        let entry = entry.unwrap();
        println!("{:?}", entry);
    }
}

Extracting an archive

use std::fs::File;

use libnar::Archive;

fn main() {
    let file = File::open("/path/to/archive.nar").unwrap();
    let mut nar = Archive::new(file).unwrap();
    nar.unpack("./archive").unwrap();
}

Creating an archive

use std::fs::File;

fn main() {
    let mut file = File::create("/path/to/archive.nar").unwrap();
    libnar::to_writer(&mut file, "/path/to/archive").unwrap();
}

License

libnar is free and open source software distributed under the terms of both the MIT and the Apache 2.0 licenses.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.