uploadID := r.Form.Get(xhttp.UploadID)
	partIDString := r.Form.Get(xhttp.PartNumber)

	partID, err := strconv.Atoi(partIDString)
	if err != nil || partID <= 0 {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrInvalidPart), r.URL)
		return
	}

	// check partID with maximum part ID for multipart objects
	if isMaxPartID(partID) {
		writeErrorResponse(ctx, w, errorCodes.ToAPIErr(ErrInvalidMaxParts), r.URL)
		return
	}

	currentFI := fi

	// Allocate parts similar to incoming slice.
	fi.Parts = make([]ObjectPartInfo, len(parts))

	var checksum hash.Checksum
	checksum.Type = checksumType

	// Validate each part and then commit to disk.
	for i, part := range parts {
		partIdx := objectPartIndex(currentFI.Parts, part.PartNumber)
		// All parts should have same part number.
		if partIdx == -1 {

	CopyObjectPart(ctx context.Context, srcBucket, srcObject, destBucket, destObject string, uploadID string, partID int,
		startOffset int64, length int64, srcInfo ObjectInfo, srcOpts, dstOpts ObjectOptions) (info PartInfo, err error)
	PutObjectPart(ctx context.Context, bucket, object, uploadID string, partID int, data *PutObjReader, opts ObjectOptions) (info PartInfo, err error)

		parts := make([]CompletePart, len(oi.Parts))
		for i, part := range oi.Parts {
			hr, err := hash.NewReader(ctx, io.LimitReader(gr, part.Size), part.Size, "", "", part.ActualSize)
			if err != nil {
				return fmt.Errorf("rebalanceObject: hash.NewReader() %w", err)
			}
			pi, err := z.PutObjectPart(ctx, bucket, oi.Name, res.UploadID,
				part.Number,
				NewPutObjReader(hr),

					ChecksumSHA1:      objInfo.Parts[i].Checksums["SHA1"],
					ChecksumSHA256:    objInfo.Parts[i].Checksums["SHA256"],
					ChecksumCRC32:     objInfo.Parts[i].Checksums["CRC32"],
					ChecksumCRC32C:    objInfo.Parts[i].Checksums["CRC32C"],
					ChecksumCRC64NVME: objInfo.Parts[i].Checksums["CRC64NVME"],
					PartNumber:        objInfo.Parts[i].Number,
					Size:              objInfo.Parts[i].Size,
				})
			}
		}