func (fi FileInfo) ObjectToPartOffset(ctx context.Context, offset int64) (partIndex int, partOffset int64, err error) {
	if offset == 0 {
		// Special case - if offset is 0, then partIndex and partOffset are always 0.
		return 0, 0, nil
	}
	partOffset = offset
	// Seek until object offset maps to a particular part offset.
	for i, part := range fi.Parts {
		partIndex = i

		readStart := false
		for i, v := range s {
			partOffset := int64(0)
			partDarePkgOffset := int64(0)
			if !readStart && cumulativeSum+v > skipLen {
				// Read starts at the current part
				readStart = true

				partOffset = skipLen - cumulativeSum

				// All return values except `l` are
				// calculated here.
				sn = uint32(partOffset / pkgSz)
				skip = partOffset % pkgSz
				ps = i

		partSize := fi.Parts[partIndex].Size

		partLength := partSize - partOffset
		// partLength should be adjusted so that we don't write more data than what was requested.
		if partLength > (length - totalBytesRead) {
			partLength = length - totalBytesRead
		}

		tillOffset := erasure.ShardFileOffset(partOffset, partLength, partSize)
		// Get the checksums of the current part.