Copy and CopyPart changes for compression (#6669)

This PR fixes

- The target object should be compressed even if the
  source object is not compressed.

- The actual size for an encrypted object should be the
  `decryptedSize`

cmd/object-handlers.go

@@ -763,9 +763,27 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 
 	var reader io.Reader
 	var length = srcInfo.Size
+
+	// Set the actual size to the decrypted size if encrypted.
+	actualSize := srcInfo.Size
+	if crypto.IsEncrypted(srcInfo.UserDefined) {
+		actualSize, err = srcInfo.DecryptedSize()
+		if err != nil {
+			writeErrorResponse(w, toAPIErrorCode(err), r.URL)
+			return
+		}
+	}
+
 	// No need to compress for remote etcd calls
 	// Pass the decompressed stream to such calls.
-	if srcInfo.IsCompressed() && !isRemoteCallRequired(ctx, srcBucket, dstBucket, objectAPI) {
+	isCompressed := objectAPI.IsCompressionSupported() && isCompressible(r.Header, srcObject) && !isRemoteCallRequired(ctx, srcBucket, dstBucket, objectAPI)
+	if isCompressed {
+		// Storing the compression metadata.
+		srcInfo.UserDefined[ReservedMetadataPrefix+"compression"] = compressionAlgorithmV1
+		srcInfo.UserDefined[ReservedMetadataPrefix+"actual-size"] = strconv.FormatInt(actualSize, 10)
+		// Remove all source encrypted related metadata to
+		// avoid copying them in target object.
+		crypto.RemoveInternalEntries(srcInfo.UserDefined)
 		// Open a pipe for compression.
 		// Where pipeWriter is piped to srcInfo.Reader.
 		// gr writes to pipeWriter.
@@ -788,26 +806,24 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 		reader = gr
 	}
 
-	srcInfo.Reader, err = hash.NewReader(reader, length, "", "", srcInfo.Size)
+	srcInfo.Reader, err = hash.NewReader(reader, length, "", "", actualSize)
 	if err != nil {
 		writeErrorResponse(w, toAPIErrorCode(err), r.URL)
 		return
 	}
 
 	var encMetadata = make(map[string]string)
-	if objectAPI.IsEncryptionSupported() && !srcInfo.IsCompressed() {
+	if objectAPI.IsEncryptionSupported() && !isCompressed {
 		// Encryption parameters not applicable for this object.
 		if !crypto.IsEncrypted(srcInfo.UserDefined) && crypto.SSECopy.IsRequested(r.Header) {
 			writeErrorResponse(w, toAPIErrorCode(errInvalidEncryptionParameters), r.URL)
 			return
 		}
-
 		// Encryption parameters not present for this object.
 		if crypto.SSEC.IsEncrypted(srcInfo.UserDefined) && !crypto.SSECopy.IsRequested(r.Header) {
 			writeErrorResponse(w, ErrInvalidSSECustomerAlgorithm, r.URL)
 			return
 		}
-
 		var oldKey, newKey []byte
 		sseCopyS3 := crypto.S3.IsEncrypted(srcInfo.UserDefined)
 		sseCopyC := crypto.SSEC.IsEncrypted(srcInfo.UserDefined) && crypto.SSECopy.IsRequested(r.Header)
@@ -973,8 +989,8 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
 		host, port = "", ""
 	}
 
-	if srcInfo.IsCompressed() {
-		objInfo.Size = srcInfo.GetActualSize()
+	if objInfo.IsCompressed() {
+		objInfo.Size = actualSize
 	}
 
 	// Notify object created event.
@@ -1470,9 +1486,7 @@ func (api objectAPIHandlers) CopyObjectPartHandler(w http.ResponseWriter, r *htt
 
 	// Get the object offset & length
 	startOffset, length, _ := rs.GetOffsetLength(actualPartSize)
-	if rangeHeader != "" {
-		actualPartSize = length
-	}
+	actualPartSize = length
 
 	/// maximum copy size for multipart objects in a single operation
 	if isMaxAllowedPartSize(length) {
@@ -1483,8 +1497,17 @@ func (api objectAPIHandlers) CopyObjectPartHandler(w http.ResponseWriter, r *htt
 	var reader io.Reader
 	var getLength = length
 
-	// Need to decompress only for range-enabled copy parts.
-	if srcInfo.IsCompressed() && rangeHeader != "" {
+	var li ListPartsInfo
+	li, err = objectAPI.ListObjectParts(ctx, dstBucket, dstObject, uploadID, 0, 1)
+	if err != nil {
+		writeErrorResponse(w, toAPIErrorCode(err), r.URL)
+		return
+	}
+	// Read compression metadata preserved in the init multipart for the decision.
+	_, compressPart := li.UserDefined[ReservedMetadataPrefix+"compression"]
+	isCompressed := compressPart
+	// Compress only if the compression is enabled during initial multipart.
+	if isCompressed {
 		// Open a pipe for compression.
 		// Where pipeWriter is piped to srcInfo.Reader.
 		// gr writes to pipeWriter.
@@ -1510,13 +1533,7 @@ func (api objectAPIHandlers) CopyObjectPartHandler(w http.ResponseWriter, r *htt
 		return
 	}
 
-	if objectAPI.IsEncryptionSupported() && !srcInfo.IsCompressed() {
-		var li ListPartsInfo
-		li, err = objectAPI.ListObjectParts(ctx, dstBucket, dstObject, uploadID, 0, 1)
-		if err != nil {
-			writeErrorResponse(w, toAPIErrorCode(err), r.URL)
-			return
-		}
+	if objectAPI.IsEncryptionSupported() && !isCompressed {
 		if crypto.IsEncrypted(li.UserDefined) {
 			if !hasServerSideEncryptionHeader(r.Header) {
 				writeErrorResponse(w, ErrSSEMultipartEncrypted, r.URL)