cerniera

A ZIP archive encoder that never copies your data.

Feed it file content through a Stream or write it directly with sendfile, mmap, or any I/O strategy you like - cerniera only encodes the ZIP framing around it.

Cerniera (/t∫erˈnjɛra/) is Italian for zipper.

Quick start

use std::{io, pin::pin};

use bytes::Bytes;
use cerniera::{MsDosDateTime, ZipEntry, ZipWriter};
use futures_util::{TryStreamExt, stream};
use tokio::{fs::File, io::AsyncWriteExt};

#[tokio::main(flavor = "current_thread")]
async fn main() -> io::Result<()> {
    let modified = MsDosDateTime::new(2026, 3, 10, 12, 30, 0);

    let entries = stream::iter([
        Ok(ZipEntry::File {
            path: "hello.txt".into(),
            modified,
            content: stream::iter([Ok(Bytes::from_static(b"Hello, world!"))]),
        }),
        Ok(ZipEntry::Directory {
            path: "subdir/".into(),
            modified,
        }),
    ]);

    let mut zip_stream = pin!(ZipWriter::new(entries));

    let mut file = File::create("output.zip").await?;
    while let Some(chunk) = zip_stream.try_next().await? {
        file.write_all(&chunk).await?;
    }
    Ok(())
}

Two API levels

• ZipWriter - high-level streaming builder. Give it entries, get a byte stream. Handles CRC-32 and all ZIP bookkeeping automatically. Files are stored (uncompressed).

• ZipArchive - low-level, sans-IO encoder. Gives you full control over buffering and compression (DEFLATE, Zstandard, etc.) at the cost of a more manual lifecycle. See the deflate_zip and sendfile_zip examples.

Features

Feature	Default	Description
std	Yes	Enables runtime SIMD detection for faster CRC-32. Everything works without it.
jiff	No	Adds From<jiff::civil::DateTime> for MsDosDateTime.

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or https://opensource.org/licenses/MIT)

at your option.

Contribution

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.