Method GetCommitDataByIndex

plumbing/format/commitgraph/v2/file.go:227–332

GetCommitDataByIndex returns the commit data for the given index in the commit-graph.

(idx uint32)

// GetCommitDataByIndex returns the commit data for the given index in the commit-graph.
func (fi *fileIndex) GetCommitDataByIndex(idx uint32) (*CommitData, error) {
	if idx < fi.minimumNumberOfHashes {
		if fi.parent != nil {
			data, err := fi.parent.GetCommitDataByIndex(idx)
			if err != nil {
				return nil, err
			}
			return data, nil
		}

		return nil, plumbing.ErrObjectNotFound
	}
	idx -= fi.minimumNumberOfHashes
	if idx >= fi.fanout[0xff] {
		return nil, plumbing.ErrObjectNotFound
	}

	offset := fi.offsets[CommitDataChunk] + int64(idx)*(hash.Size+szCommitData)
	commitDataReader := io.NewSectionReader(fi.reader, offset, hash.Size+szCommitData)

	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 []uint32
	if parent2&parentOctopusUsed == parentOctopusUsed {
		// Octopus merge - Look-up the extra parents from the extra edge list
		// The extra edge list is a list of uint32s, each of which is an index into the Commit Data table, terminated by a index with the most significant bit on.
		parentIndexes = []uint32{parent1 & parentOctopusMask}
		offset := fi.offsets[ExtraEdgeListChunk] + szUint32*int64(parent2&parentOctopusMask)
		buf := make([]byte, szUint32)
		for {
			_, err := fi.reader.ReadAt(buf, offset)
			if err != nil {
				return nil, err
			}

			parent := encbin.BigEndian.Uint32(buf)
			offset += szUint32
			parentIndexes = append(parentIndexes, parent&parentOctopusMask)
			if parent&parentLast == parentLast {
				break
			}
		}
	} else if parent2 != parentNone {