BitRock unpacker prototype

bitrock_unpacker is a module for extracting content of BitRock/InstallBuilder installers without Tcl/TclKit.

I created that repo since I was not able to run original Tcl unpacker from here on Windows.

Run without installing:

uvx bitrock-unpacker --help

Run as a module:

python -m bitrock_unpacker --help

If installed, it also exposes:

bitrock-unpacker --help

Current capabilities

• Parses PE overlay boundaries.
• Locates BitRock/CookFS markers.
• Recovers manifest.txt from the embedded zlib stream.
• Parses old CookFS CFS0002 suffix/page tables.
• Decompresses CookFS pages: raw, raw deflate, bzip2, and LZMA-Alone.
• Decodes the CookFS CFS2.200 fsindex.
• Lists and extracts files by fsindex path.
• Stitches BitRock big-file chunks named ___bitrockBigFileN into their base file by default.

Limitations

• Encrypted/proprietary maui::util payloads are not supported.
• Full installer post-processing is out of scope; extraction writes archive contents.
• Full extraction requires --yes-all when no --limit is supplied.

Use --raw-chunks to show or extract hidden ___bitrockBigFileN chunk files instead of stitching them.

Quick checks

The pyproject.toml metadata exposes the bitrock-unpacker console script, so the same CLI can be checked through uv run without installing it globally:

python -m bitrock_unpacker <installer.exe> --manifest-only --debug
python -m bitrock_unpacker <installer.exe> --list-pages --limit 5
python -m bitrock_unpacker <installer.exe> --list-files --limit 10

Extract one file:

python -m bitrock_unpacker <installer.exe> `
  --path path/inside/archive.txt `
  --extract $env:TEMP\files `
  --limit 1

Inspect raw hidden chunks:

python -m bitrock_unpacker <installer.exe> `
  --raw-chunks `
  --list-files `
  --path path/inside/archive.bin___bitrockBigFile1 `
  --limit 5

Full stitched extraction can be large:

python -m bitrock_unpacker <installer.exe> --extract out --yes-all

Development

Validate the project metadata and run the self-test:

python -c "import tomllib; tomllib.load(open('pyproject.toml','rb')); print('pyproject: ok')"
python -m py_compile bitrock_unpacker\*.py