Difference between revisions of "ZiPatch File Structure"

Revision as of 18:44, 6 June 2019

History

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 that are 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.

Initial, minimal research of the ZiPatch file format was made publically available [1] in 2013 by Jean-Philip Desjardins for his open-source server emulator for FINAL FANTASY XIV, SeventhUmbral [2]. This implementation allowed the ZiPatch files that were backed up by Krizz [3] and others in the community to be applied to a new installation and incorrectly update the client to 1.23b.

File Header

ZiPatch files have a unique file header (12 bytes), which is used to identify the file format. The ZiPatch File Header is immediately followed by n blocks, each of which provide ffxivupdater.exe with information to carry out specific instructions.

91 5A 49 50 41 54 43 48 0D 0A 1A 0A            ‘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 slice of data[0..3] is a string used to identify the block type. Static analysis of ffxivupdater.exe indicates the following block types as valid.

FHDR
APLY
APFS
ETRY
ADIR
DELD

FHDR

FHDR blocks are an abstract of the changes that should occur as a result of applying the ZiPatch in terms of the type and count of the changes to be made.

struct fhdr_t
{
    char version[4];  // [00 00 02 00] observed; Static analysis of ffxivupdater.exe indicates FileHeaderV2
    char result[4];   // DIFF or HIST observed
    int numEntryFile; // LE
    int numAddDir;    // LE
    int numDeleteDir; // LE
}

APLY

APFS

APFS blocks are have not been observed directly in ZiPatch files and currently their purpose is unknown.

ETRY

ADIR

ADIR blocks provide the information for ffxivupdater.exe to make changes directly to the filesystem by creating a new directory for the specified path, relative to the installation directory, if it does not already exist.

struct adir_t
{
    int pathSize; // LE
    char* path;
}

DELD