Merge "Add CowOperationV2" into main am: a10bfe1d am: 445d13f7 am:...

    uint64_t source;

} __attribute__((packed));

// The on disk format of cow (currently ==  CowOperation)

struct CowOperationV2 {

    // The operation code (see the constants and structures below).

    uint8_t type;

    // If this operation reads from the data section of the COW, this contains

    // the compression type of that data (see constants below).

    uint8_t compression;

    // If this operation reads from the data section of the COW, this contains

    // the length.

    uint16_t data_length;

    // The block of data in the new image that this operation modifies.

    uint64_t new_block;

    // The value of |source| depends on the operation code.

    //

    // For copy operations, this is a block location in the source image.

    //

    // For replace operations, this is a byte offset within the COW's data

    // sections (eg, not landing within the header or metadata). It is an

    // absolute position within the image.

    //

    // For zero operations (replace with all zeroes), this is unused and must

    // be zero.

    //

    // For Label operations, this is the value of the applied label.

    //

    // For Cluster operations, this is the length of the following data region

    //

    // For Xor operations, this is the byte location in the source image.

    uint64_t source;

} __attribute__((packed));

static_assert(sizeof(CowOperationV2) == sizeof(CowOperation));

static_assert(sizeof(CowOperation) == sizeof(CowFooterOperation));

static constexpr uint8_t kCowCopyOp = 1;

    void UpdateMergeOpsCompleted(int num_merge_ops) { header_.num_merge_ops += num_merge_ops; }

  private:

    bool ParseOps(std::optional<uint64_t> label);

    bool PrepMergeOps();

    uint64_t FindNumCopyops();

    uint8_t GetCompressionType(const CowOperation* op);