ZiPatch File Structure

All ZiPatch files for FINAL FANTASY XIV share the same overall structure. This format was later expanded in 2012 for DRAGON QUEST X and FINAL FANTASY XIV: A Realm Reborn, which are more similar in their DAT structure. Many of the block types found in this version were deprecated, but still remain in the executable for A Realm Reborn.

ZiPatch Header

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

The ZiPatch File Header is followed immediately by n blocks, which each carry specific instructions.

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; 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
}