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June 6, 2026 • 6 min read

OxiArc 0.3.3 Released — Brotli Now Round-Trips Incompressible Data Byte-for-Byte

OxiArc 0.3.3 is a correctness release: Brotli now round-trips high-entropy and incompressible data byte-for-byte across all quality levels 1–11. A package-merge Huffman code generator and an extended insert-length table fix two long-standing encoder bugs. Pure Rust, on-the-wire compatible, 1,679 tests passing.

release oxiarc brotli compression correctness huffman pure-rust bugfix

An archiver earns trust one corner case at a time. Today we closed a sharp one.

Today we released OxiArc 0.3.3 — a correctness release in which Brotli now round-trips high-entropy and incompressible data byte-for-byte across every quality level from 1 to 11.

No C. No Fortran. No zlib. No libarchive. No external shared libraries. No FFI overhead. No build hell. Just clean, memory-safe, blazing-fast archiving and compression that compiles to a single static binary, targets WASM, and runs everywhere.

OxiArc is the Pure Rust replacement for the zip, tar, gzip, zstd, and 7-zip tools — and for the Rust crates zip, flate2, zstd, bzip2, lz4, tar, snap, brotli, and miniz_oxide.

Why 0.3.3 matters

Compressors meet two kinds of data: the kind that shrinks, and the kind that does not. Already-compressed files, encrypted blobs, and truly random bytes do not shrink — and a serious codec must still round-trip them faithfully. Previously, oxiarc-brotli could fail to decode near-uniform or incompressible inputs. 0.3.3 fixes that. It is a real robustness win, not a new feature, and it is on-the-wire compatible — the fix is entirely internal, with no API change, so streams you already produced keep working.

Two underlying bugs were behind the failures:

  1. Incomplete length-limited Huffman codes. For near-uniform literal distributions where every symbol is present, the old compute_code_lengths heuristic — ideal ceil(-log2 p) lengths plus a Kraft-inequality fix-up loop — could emit a code-length table whose Kraft sum was strictly below 2^15. That is an incomplete prefix code: the decoder would eventually hit a bit pattern that decoded to no symbol at all (“invalid Huffman code: no matching code found”).
  2. Insert lengths above 319 silently truncated. A single incompressible meta-block is one insert-and-copy command whose insert length spans the entire block. But the encoder only had insert-length categories 0–15 (max base 192, i.e. insert length ≤ 319), and it wrote the excess into a 7-bit field that wrapped around — desynchronising the decoder and producing a content mismatch.

A focused technical note on the fixes

The repairs go to the root of each bug rather than papering over the symptoms:

The result: 1,679 tests passing, 2 skipped (13 new), zero Clippy warnings under -D warnings, zero rustdoc warnings, all COOLJAPAN policies compliant.

Getting Started

CLI:

cargo install oxiarc-cli

Library:

cargo add oxiarc-brotli

The fix needs nothing from you — it is internal. Existing OxiArc code keeps working unchanged. Here is the basic library shape, compressing a buffer and walking a ZIP archive:

use oxiarc_deflate::{deflate, inflate};
use oxiarc_archive::ZipReader;
use std::fs::File;

let compressed = deflate(b"Hello, World!", 6)?;
let decompressed = inflate(&compressed)?;

let file = File::open("archive.zip")?;
let mut zip = ZipReader::new(file)?;
for entry in zip.entries() {
    println!("{}: {} bytes", entry.name, entry.size);
}

On the Brotli side, you compress at a quality level from 0 to 11 just as before — the new code generator and extended insert-length table simply make every level correct on every input, including data that does not compress.

What’s New in 0.3.3

Tips

This is the foundation

This is the kind of correctness hardening you expect from an archiver the whole stack leans on. Incompressible payloads are routine: pre-compressed media in OxiMedia, encrypted attachments in RusMES, already-packed scientific arrays in SciRS2 / NumRS2, opaque geospatial tiles in OxiGDAL, and mixed-content ingestion in ToRSh / OxiRAG. Every one of them needs a codec that round-trips data that does not shrink. With 0.3.3, OxiArc’s Brotli does — byte-for-byte, at every quality level, in Pure Rust.

Repository: https://github.com/cool-japan/oxiarc

Star the repo if you want archiving and compression you can trust on every kind of input, without the traditional native toolchain headaches.

The era of “just use zlib” or “link libarchive” is coming to an end.

— KitaSan at COOLJAPAN OÜ June 6, 2026

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