// Parts in FileInfo should be in sorted order by part number.
	sort.Slice(fi.Parts, func(i, j int) bool { return fi.Parts[i].Number < fi.Parts[j].Number })
}

// ObjectToPartOffset - translate offset of an object to offset of its individual part.
func (fi FileInfo) ObjectToPartOffset(ctx context.Context, offset int64) (partIndex int, partOffset int64, err error) {
	if offset == 0 {

	partIndex, partOffset, err := fi.ObjectToPartOffset(ctx, startOffset)
	if err != nil {
		return InvalidRange{startOffset, length, fi.Size}
	}

	// Calculate endOffset according to length
	endOffset := startOffset
	if length > 0 {
		endOffset += length - 1
	}

	// Get last part index to read given length.
	lastPartIndex, _, err := fi.ObjectToPartOffset(ctx, endOffset)
	if err != nil {