Module compactpro 

Compact Pro (.cpt) archive reader — Bill Goodman’s Compactor / Compact Pro format, common for vintage Mac software and frequently distributed as a BinHex-wrapped self-extracting archive (.sea.hqx).

Two-stage compression: a byte-level RLE layer, optionally fed by an LZH (LZSS + canonical Huffman) layer. Each file carries a data and/or resource fork plus Finder info, mapping cleanly onto the shared StuffItEntry / StuffItArchive plumbing the rest of macarchive already uses, so the directory tree and all four output formats in extract come for free.

Ported from XADMaster’s XADCompactProParser.m, XADCompactProRLEHandle.m, and XADCompactProLZHHandle.m (which build on XADLZSSHandle, XADPrefixCode, and CSInputBuffer, all under ~/repos/XADMaster). The block-padding quirk in the LZH layer and the RLE escape sequence are faithful reproductions of that reference.

Functions

decompress_fork

Decompress one Compact Pro fork (RLE, optionally LZH-fed). The CRC is not checked here — Compact Pro stores one checksum per file covering the resource fork followed by the data fork, so the caller verifies it once both forks are in hand via verify_entry_crc.

is_compactpro

True iff bytes is a Compact Pro archive. Mirrors XADMaster’s recognizer: the leading 0x01 marker is far too weak on its own, so we walk the index at the end of the file and confirm the stored CRC-32 over the directory.

parse

Parse a Compact Pro archive’s directory into the shared entry tree. Fork data offsets are absolute within bytes, exactly like the StuffIt parsers.

verify_entry_crc

Verify a Compact Pro file’s CRC-32. The stored checksum covers the decompressed resource fork immediately followed by the decompressed data fork (either may be empty), as a single reflected CRC-32 with no final complement. This is the only integrity check for the format, so it runs for every entry — single-fork, dual-fork, and empty alike.