op: Address review issues

op/upload.go

@@ -75,18 +75,17 @@ func Upload(ctx context.Context, blobServiceClient *service.Client, container, b
 	}
 
 	if opts == nil {
-		opts = &UploadOptions{}
+		opts = &UploadOptions{
+			Logger: noopLogger,
+		}
 	}
 
 	parallelism := 8 * runtime.NumCPU()
 	if opts.Parallelism > 0 {
 		parallelism = opts.Parallelism
 	}
 	overwrite := opts.Overwrite
-	logger := noopLogger
-	if opts.Logger != nil {
-		logger = opts.Logger
-	}
+	logger := opts.Logger
 
 	if err := ensureVHDSanity(vhd); err != nil {
 		return err
@@ -204,7 +203,7 @@ func ensureVHDSanity(vhd string) error {
 // metadata. The parameter client is the Azure pageblob client
 // representing a blob in a container, size is the size of the new
 // page blob in bytes and parameter vhdMetadata is the custom metadata
-// to be associacted with the page blob.
+// to be associated with the page blob.
 func createBlob(ctx context.Context, client *pageblob.Client, size int64, vhdMetadata *metadata.Metadata) error {
 	m, err := vhdMetadata.ToMap()
 	if err != nil {
@@ -219,7 +218,7 @@ func createBlob(ctx context.Context, client *pageblob.Client, size int64, vhdMet
 
 // setBlobMD5Hash sets MD5 hash of the blob in its properties
 func setBlobMD5Hash(ctx context.Context, client *blob.Client, vhdMetadata *metadata.Metadata) error {
-	if vhdMetadata.FileMetadata.MD5Hash == nil {
+	if vhdMetadata.FileMetadata == nil || len(vhdMetadata.FileMetadata.MD5Hash) == 0 {
 		return nil
 	}
 	buf := make([]byte, base64.StdEncoding.EncodedLen(len(vhdMetadata.FileMetadata.MD5Hash)))