Applesauce

Applesauce is a command-line interface (CLI) program written in Rust that compresses, decompresses, and prints information about compressed files for HFS+/APFS transparent compression on macOS. It is based on afsctool and offers several key improvements, including better performance, improved multithreading (even for a single file), and reduced memory usage. Applesauce supports all three compression algorithms used by HFS+/APFS: LZFSE, LZVN, and ZLIB.

Installation

Building with Cargo

To install Applesauce using Cargo, follow these steps:

1. Install Rust and Cargo using the instructions provided at rust-lang.org.
2. Clone this repository to your local machine.
3. In the project directory, run cargo build --release to build the program.
4. The built binary can be found in the target/release directory.

Installing from GitHub Releases

Alternatively, you can download pre-built binaries from the GitHub releases page.

Usage

To use Applesauce, run the following command:

applesauce [compress|decompress|info] file/directory

The options are as follows:

• compress: Compresses the specified file/directory using one of three compression algorithms (LZFSE, LZVN, or ZLIB).
• decompress: Decompresses the specified file/directory.
• info: Prints information about the specified compressed file/directory, including the compression ratio and compression algorithm used.

For example, to compress a file named example.txt using the ZLIB compression algorithm, you would run:

applesauce compress -c ZLIB example.txt

Features

Applesauce has the following key features:

• Supports three compression algorithms: LZFSE, LZVN, and ZLIB.
• Can print information about compressed files, including the compression ratio and compression algorithm used.
• Supports transparent compression for HFS+/APFS on macOS.

Compression Algorithms

Applesauce supports three compression algorithms:

• LZFSE: This compression algorithm was developed by Apple for use on iOS and macOS. It is a fast compression algorithm that offers a good balance between compression ratio and speed.
• LZVN: This compression algorithm was also developed by Apple for use on iOS and macOS. It is optimized for use on 64-bit processors and offers a high compression ratio.
• ZLIB: This is a widely used compression algorithm that is implemented in many software packages. It is slower than LZFSE and LZVN, but can offer a higher compression ratio (especially with -l 9, but not always: it depends on the type of data being compressed).

Applesauce defaults to using LZFSE compression. Depending on the type of data being compressed and the desired balance between compression ratio and speed, one of these algorithms may be more suitable than the others.

Improvements Over Afsctool

Applesauce is based on afsctool, but offers several key improvements, including:

Improved Performance

afcstool can compress multiple files in parallel, but applesauce parallelizes at the block level, so even a single file can be compressed in parallel. Applesauce can often be several times faster than afsctool, especially for small numbers of large files.

Reduced Memory Usage

afcstool will load the entire file into memory before compressing it (although it does attempt to use mmap for large files). Applesauce will only keep the block(s) currently being compressed in memory.

Better User Interface

Applesauce outputs a pretty progress bar while it's working, providing a more user-friendly experience than afsctool's sparse output.

Better Compression With Many Small Files

afsctool will compress a file which fits in the xattr after compression, even if doing so actually adds more overhead than leaving the file uncompressed. Applesauce will not compress a file if it would result in a larger file.

Better Error Handling

afcstool overwrites files in place. Although it attempts to restore the file if an error occurs, if it is forcefully terminated while compressing a file, the file may be left in an invalid state.

Applesauce compresses/decompresses files to a temporary file and then atomically renames the temporary file to the original file only when the operation is complete: the file is never left in an invalid state, even if the program is harshly terminated.

This is no replacement for backups: please do not use applesauce on files you cannot afford to lose.

License

Applesauce is licensed under the GNU General Public License version 3 (GPLv3).

Contributions

Contributions to Applesauce are welcome! If you would like to contribute code, please open a pull request on the GitHub repository. If you find a bug or have a feature request, please open an issue on the repository.