// CheckPreconditionFn returns true if precondition check failed.
type CheckPreconditionFn func(o ObjectInfo) bool

// EvalMetadataFn validates input objInfo and GetObjectInfo error and returns an updated metadata and replication decision if any
type EvalMetadataFn func(o *ObjectInfo, gerr error) (ReplicateDecision, error)

// update metadata.
func (er erasureObjects) CopyObject(ctx context.Context, srcBucket, srcObject, dstBucket, dstObject string, srcInfo ObjectInfo, srcOpts, dstOpts ObjectOptions) (oi ObjectInfo, err error) {
	if !dstOpts.NoAuditLog {
		auditObjectErasureSet(ctx, "CopyObject", dstObject, &er)
	}

	// This call shouldn't be used for anything other than metadata updates or adding self referential versions.

	uploadID := base64.RawURLEncoding.EncodeToString(fmt.Appendf(nil, "%s.%s", globalDeploymentID(), uploadUUID))
	uploadIDPath := er.getUploadIDDir(bucket, object, uploadUUID)

	// Write updated `xl.meta` to all disks.
	if _, err := writeAllMetadata(ctx, onlineDisks, bucket, minioMetaMultipartBucket, uploadIDPath, partsMetadata, writeQuorum); err != nil {
		return nil, toObjectErr(err, bucket, object)
	}

	restoreExpiry := lifecycle.ExpectedExpiryTime(time.Now().UTC(), rreq.Days)
	metadata := cloneMSS(objInfo.UserDefined)

	// update self with restore metadata
	if rreq.Type != SelectRestoreRequest {
		objInfo.metadataOnly = true // Perform only metadata updates.
		metadata[xhttp.AmzRestoreExpiryDays] = strconv.Itoa(rreq.Days)
		metadata[xhttp.AmzRestoreRequestDate] = time.Now().UTC().Format(http.TimeFormat)

		}
	}

	srcInfo.PutObjReader = pReader
	copyObjectPart := objectAPI.CopyObjectPart

	// Copy source object to destination, if source and destination
	// object is same then only metadata is updated.
	partInfo, err := copyObjectPart(ctx, srcBucket, srcObject, dstBucket, dstObject, uploadID, partID,
		startOffset, length, srcInfo, srcOpts, dstOpts)
	if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)