struct HFSPlusForkData {
    UInt64                  logicalSize;
    UInt32                  clumpSize;
    UInt32                  totalBlocks;
    HFSPlusExtentRecord     extents;
};
typedef struct HFSPlusForkData HFSPlusForkData;
 
typedef HFSPlusExtentDescriptor HFSPlusExtentRecord[8];

struct HFSPlusExtentDescriptor {
    UInt32                  startBlock;
    UInt32                  blockCount;
};
typedef struct HFSPlusExtentDescriptor HFSPlusExtentDescriptor;