Method GetCommitDataByIndex

plumbing/format/commitgraph/file.go:187–249

(idx int)

}

func (fi *fileIndex) GetCommitDataByIndex(idx int) (*CommitData, error) {
	if idx >= fi.fanout[0xff] {
		return nil, plumbing.ErrObjectNotFound
	}

	offset := fi.commitDataOffset + int64(idx)*(hash.Size+commitDataSize)
	commitDataReader := io.NewSectionReader(fi.reader, offset, hash.Size+commitDataSize)

	treeHash, err := binary.ReadHash(commitDataReader)
	if err != nil {
		return nil, err
	}
	parent1, err := binary.ReadUint32(commitDataReader)
	if err != nil {
		return nil, err
	}
	parent2, err := binary.ReadUint32(commitDataReader)
	if err != nil {
		return nil, err
	}
	genAndTime, err := binary.ReadUint64(commitDataReader)
	if err != nil {
		return nil, err
	}

	var parentIndexes []int
	if parent2&parentOctopusUsed == parentOctopusUsed {
		// Octopus merge
		parentIndexes = []int{int(parent1 & parentOctopusMask)}
		offset := fi.extraEdgeListOffset + 4*int64(parent2&parentOctopusMask)
		buf := make([]byte, 4)
		for {
			_, err := fi.reader.ReadAt(buf, offset)
			if err != nil {
				return nil, err
			}

			parent := encbin.BigEndian.Uint32(buf)
			offset += 4
			parentIndexes = append(parentIndexes, int(parent&parentOctopusMask))
			if parent&parentLast == parentLast {
				break
			}
		}
	} else if parent2 != parentNone {
		parentIndexes = []int{int(parent1 & parentOctopusMask), int(parent2 & parentOctopusMask)}
	} else if parent1 != parentNone {
		parentIndexes = []int{int(parent1 & parentOctopusMask)}
	}

	parentHashes, err := fi.getHashesFromIndexes(parentIndexes)
	if err != nil {
		return nil, err
	}

	return &CommitData{
		TreeHash:      treeHash,
		ParentIndexes: parentIndexes,