LZMA / LZMA2 / LZIP / XZ in native Rust

LZMA / LZMA2 / LZIP / XZ compression ported from tukaani xz for java.

This is a fork of the original, unmaintained lzma-rust crate to continue the development and maintenance.

Safety

Only the optimization feature uses unsafe Rust features to implement optimizations, that are not possible in safe Rust. Those optimizations are properly guarded and are of course sound. This includes creation of aligned memory, handwritten assembly code for hot functions and some pointer logic. Those optimization are well localized and generally consider safe to use, even with untrusted input.

Deactivating the optimization feature will result in 100% standard Rust code.

Performance

The following part is strictly about single threaded performance. It supports multithreaded encoding and decoding through the LZMA2WriterMT and LZMA2ReaderMT structs though.

When compared against the liblzma crate, which uses the C library of the same name, this crate has improved decoding speed.

Encoding is also well optimized and is surpassing liblzma for level 0 to 3 and matches it for level 4 to 9.

Data was assembled using lzma-rust2 v0.4.0 and liblzma v0.4.2.

no_std Support

This crate supports no_std environments by disabling the default std feature.

When used in no_std mode, the crate provides custom Read, Write, and Error types (defined in no_std.rs) that are compatible with no_std environments. These types offer similar functionality to their std::io counterparts but are implemented using only core and alloc.

The custom types include:

• Error: A custom error enum with variants for different error conditions.
• Read: A trait similar to std::io::Read.
• Write: A trait similar to std::io::Write.

Default implementations for &[u8] (Read) and &mut [u8] (Write) are provided.

Note that multithreaded features are not available in no_std mode as they require standard library threading primitives.

License

Licensed under the Apache License, Version 2.0.