return optional

bindings/java/src/org/sleuthkit/datamodel/AbstractFile.java

@@ -1080,7 +1080,7 @@ private boolean loadContentStream() throws TskCoreException {
 			return true;
 		} else if (tryContentStream) {
 			// only attempt to load if the flag indicates it should be tried	
-			contentStream = getSleuthkitCase().getContentProvider().getContentStream(this);
+			contentStream = getSleuthkitCase().getContentProvider().getContentStream(this).orElse(null);
 
 			if (contentStream == null) {
 				// if no content stream could be loaded, mark tryContentStream as false so load 
@@ -1106,15 +1106,11 @@ private boolean useContentProvider() {
 	@Override
 	public final int read(byte[] buf, long offset, long len) throws TskCoreException {
 		//template method
-		//if localPath is set, use local, otherwise, use readCustom() supplied by derived class
-		if (useContentProvider()) {
-			if (loadContentStream()) {
-				return this.contentStream.read(buf, offset, len);
-			} else {
-				return 0;
-			}
+		if (useContentProvider() && loadContentStream()) {
+			return this.contentStream.read(buf, offset, len);
 		}
 		
+		//if localPath is set, use local, otherwise, use readCustom() supplied by derived class
 		if (localPathSet) {
 			return readLocal(buf, offset, len);
 		} else {

bindings/java/src/org/sleuthkit/datamodel/ContentStream.java

@@ -18,6 +18,8 @@
  */
 package org.sleuthkit.datamodel;
 
+import java.util.Optional;
+
 /**
  * Custom provider for content bytes.
  */
@@ -44,14 +46,14 @@ public interface ContentStream {
 	public interface ContentProvider {
 
 		/**
-		 * Provides a content stream for a content object or null if this
+		 * Provides a content stream for a content object or empty if this
 		 * provider has none to provide.
 		 *
 		 * @param content The content.
 		 *
-		 * @return The content stream or null if no stream can be provided
+		 * @return The content stream or empty if no stream can be provided
 		 *         for this content.
 		 */
-		ContentStream getContentStream(Content content) throws TskCoreException;
+		Optional<ContentStream> getContentStream(Content content) throws TskCoreException;
 	}
 }