Module stuffit 

Classic StuffIt (.sit) + StuffIt self-extracting (.sea) reader.

Container layout (reverse-engineered; see XADMaster XADStuffItParser.m, mirrored in docs/native_mac_archives.md):

Archive header (22 bytes):
  [0..4]  "SIT!" magic
  [4..6]  number of entries (u16 BE)        (informational; we walk to EOF)
  [6..10] total archive length (u32 BE)
  [10..14] "rLau" secondary signature
  [14..22] version + reserved + header CRC

Per-entry header (112 bytes):
  [0]   resource-fork compression method
  [1]   data-fork compression method
  [2]   filename length (<= 31)
  [3..34] filename (Mac Roman)
  [66..70] file type        [70..74] creator
  [74..76] Finder flags
  [76..80] creation date    [80..84] modification date  (Mac 1904 epoch)
  [84..88] resource fork uncompressed length
  [88..92] data fork uncompressed length
  [92..96] resource fork compressed length
  [96..100] data fork compressed length
  [100..102] resource CRC   [102..104] data CRC  (CRC-16/ARC)
  [110..112] header CRC (CRC-16/ARC over [0..110])
Then: <compressed resource fork><compressed data fork>

A method byte’s high bit (0x80) marks an encrypted fork; 0x20/0x21 (after masking the encryption + folder-contains-encrypted bits) mark the start/end of a folder. The low nibble is the compression method.

Structs

ForkInfo

One fork (data or resource) of a StuffIt or Compact Pro entry.

SitDamage

Bytes between two entries that no header accounts for, skipped by the entry walk (#101). See docs/native_mac_archives.md section 6a.

SitTruncation

An archive whose header declares a longer stream than is present.

StuffItArchive

A parsed StuffIt archive (entries in archive order; directory structure is reflected in each entry’s path).

StuffItEntry

One file or folder in a StuffIt archive.

StuffItInput

A single file to place into a StuffIt archive.

Enums

ForkCodec

Which decompressor a ForkInfo needs. StuffIt and Compact Pro share the same entry/fork plumbing (the directory tree in StuffItEntry and every output format in extract) but use entirely different fork codecs and checksums, so the codec tag picks the right decompressor at extract time.

StuffItInputNode

A node in a StuffIt input tree — either a file or a folder containing further nodes. Used by build_archive_tree to emit nested directory structures via the START_FOLDER (0x20) / END_FOLDER (0x21) marker entries that classic StuffIt uses for hierarchy.

WriteMethod

Compression to use when writing a fork.

Functions

build_archive

Build a classic StuffIt (.sit) archive from a flat list of files.

build_archive_tree

Build a classic StuffIt (.sit) archive from a node tree, emitting START_FOLDER (0x20) / END_FOLDER (0x21) marker entries for nested directories. Children of a Folder node appear between its start and end markers; the round-trip through parse reconstructs the directory path in each entry’s path field.

decompress_fork

Decompress one fork from the archive bytes, verifying its CRC.

find_sea_archive

Locate the StuffIt archive inside a .sea (self-extracting archive). A StuffIt SEA is a Mac application whose payload is a plain .sit stream; we scan for the SIT!…rLau signature. Returns the offset of the archive.

is_stuffit

Detect whether data begins with a classic StuffIt archive.

parse

Parse a StuffIt archive (or the .sit stream embedded in a .sea).