Difference between revisions of "ZiPatch File Structure"

Revision as of 16:29, 6 June 2019

ZiPatch Background

ZiPatch (.patch) files are a compressed file format for FINAL FANTASY XIV. This file format was later modified in 2012 for DRAGON QUEST X and FINAL FANTASY XIV: A Realm Reborn, which are more similar in their DAT structure to each other than to FINAL FANTASY XIV. As such, many of the block types found in this version have been deprecated; however, static analysis of the A Realm Reborn executables indicate that they may still be able to read this version.

ZiPatch File Header

ZiPatch files have a unique file header, which is used to identify the file format. The ZiPatch File Header is immediately followed by n blocks, each of which carry specific instructions.

91 5A 49 50 41 54 43 48 0D 0A 1A 0A            ‘ZIPATCH....

ZiPatch Block Structure

[StructLayout(LayoutKind.Sequential, Pack=4)]
struct Block
{
    int _dataSize; // Little Endian
    byte[] _data;  // data.Length is dataSize + 4 (inclusive of block type identifier)
    [MarshalAs(UnmanagedType.ByValArray, SizeConst=4)]
    byte[] _crc;   // crc is a standard CRC32 checksum (RFC 1952) of data
}

The block type identifier is indicated by the slice of data[0..3]. Analysis of ffxivupdater.exe indicates the following block types as valid:

FHDR // File Header; observed
APLY // Unknown; [00 00 00 01 00 00 00 04 00 00 00 01] and [00 00 00 02 00 00 00 04 00 00 00 01] observed
APFS // Unknown; not observed
ETRY // Entry File; observed
ADIR // Add Directory; observed
DELD // Delete Directory; observed

File Header

The File Header block is a summary of the changes that will take place as a result of applying the ZiPatch.

[StructLayout(LayoutKind.Sequential, Pack=4, Size=20)]
struct FileHeader
{
    [MarshalAs(UnmanagedType.ByValArray, SizeConst=4)]
    byte[] _version;         // version format is unknown, but may be major/minor. Analysis of ffxivupdater.exe indicates the string FileHeaderV2. [00 00 02 00] observed

    [MarshalAs(UnmanagedType.ByValArray, SizeConst=4)]
    byte[] _result;          // DIFF or HIST observed

    int _numEntryFile;       // Little Endian
    int _numAddDirectory;    // Little Endian
    int _numDeleteDirectory; // Little Endian
}