PAR (Package ARchive)

A minimal file archive format, and a command-line utility to bundle and extract them.

Usage

par.lua is designed for use on ComputerCraft machines. To run it on a standard system, use cc-desk.

Create archive: par <archive> <files to bundle...>
Extract archive: par -x <archive>

Examples:
> par archive.par hello.txt song.dfpwm
> par programs.par rom/programs/*
> par -x archive.par
> par -x programs.par

Format

PAR archives contain a header with a list of entries, and the file data itself.

Header

The archive begins with a 1-byte version and 2-byte entry_count. As of writing, the current version is 1.

Entry List

Immediately following the header is an entry_count-long list of entries with the following format:

Size	Name	Description
1	path_length	Length of the following path field in bytes
path_length	path	Path of this entry, should be treated as relative to the extraction directory
4	offset	Offset in this archive where the contents of this file are located
1	flags	Set of bitflags (currently unused)

After the entry list is a blob containing the (currently uncompressed) contents of every file in the archive. There may be a gap between the end of the entry list and the beginning of the contents, but there must not be a gap between the contents of each file, and they must be in the order listed in the entry list.