JOEPack format

This is a simple file format that just crams a bunch of files together, like a zip file, but without any compression.

Technical specification

"JoePack" is a binary file format in which multi-byte values are expressed with the little-endian byte order. This section details version 1 of the file format.

Note: This documentation was generated by reverse engineering the source code. So there may be errors in evaluation.

Data Type Map

The following table explicitly defines the various data types used in a JOE file.

Identifier	Detailed Description
unsigned int	32-bit un-signed integer
unsigned short	16-bit un-signed integer
string[x]	Array of characters with length x

File Header

This block of information initiates every file.

Data type	Block offset	Name	Description
string[8]	0	versionstr	Report the file version that this file conforms to. This specification details version 1 of the format.
unsigned int	8	numobjs	This is the number of files contained in the pack
unsigned int	12	maxstrlen	The maximum file name length in this pack

File Allocation Table (FAT)

The FAT consists of numobjs entries of the following format:

Data type	Block offset	Name	Description
unsigned int	0	offset	Offset into the file at which this file starts. This offset is in bytes from the beginning of the file.
unsigned int	4	length	The length of the file this entry corresponds to.
string[maxstrlen]	8	filename	The name of the file stored at this entry. Note that this is not necessarily null terminated - VDrift stores it in a string of length maxstrlen + 1 and pads it with a null character at the end

File Data

Following the FAT, the JoePack file simply consists of all the data stored sequentially. Seeking to the offset specified in the FAT (from the beginning of the file) will allow you to read that file's data like normal.