Vunzip

vunzip is a command-line utility to unzip Valve's custom .vz compressed files.

Building

On OS X, use the supplied Xcode project.

On Linux, use the Makefile.

This code has not been extensively tested on Windows, Linux or anything else, but I don't see why it shouldn't work there.

Credits

• johndrinkwater for his reference implementation in Python.
• Ymgve for the file format details (see the reference implementation).
• SteamDB IRC for collectively figuring out the format so quickly.
• XNU on Apple Open-Source and Gary S. Brown for having an easily and permissibly stealable C CRC32 implementation
• LZMA SDK (public-domain)

File format

Header

• 2 bytes: 'VZ'
• 1 bytes: Format version ('a')
• 4 bytes: POSIX timestamp, assumedly of when the file was created

Body

• LZMA-compressed content

Footer

• 4 bytes: CRC32 of the decompressed content
• 4 bytes: size of the decompressed content
• 2 bytes: 'zv'