Bug 56240 - Handle PP97_DUALSTORAGE streams

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1648466 13f79535-47bb-0310-9956-ffa450edef68

src/scratchpad/src/org/apache/poi/hslf/HSLFSlideShow.java

@@ -173,9 +173,8 @@ public final class HSLFSlideShow extends POIDocument {
 	 * @param dir the POIFS directory to read from
 	 * @throws IOException if there is a problem while parsing the document.
 	 */
-	public HSLFSlideShow(DirectoryNode dir) throws IOException
-	{
-		super(dir);
+	public HSLFSlideShow(DirectoryNode dir) throws IOException {
+		super(handleDualStorage(dir));
 
 		// First up, grab the "Current User" stream
 		// We need this before we can detect Encrypted Documents
@@ -192,7 +191,13 @@ public final class HSLFSlideShow extends POIDocument {
 		readOtherStreams();
 	}
 	
-	
+	private static DirectoryNode handleDualStorage(DirectoryNode dir) throws IOException {
+	    // when there's a dual storage entry, use it, as the outer document can't be read quite probably ...
+	    String dualName = "PP97_DUALSTORAGE";
+	    if (!dir.hasEntry(dualName)) return dir;
+	    dir = (DirectoryNode)dir.getEntry(dualName);
+	    return dir;
+	}
 	
 	/**
 	 * Constructs a new, empty, Powerpoint document.

src/scratchpad/testcases/org/apache/poi/hslf/usermodel/TestBugs.java

@@ -610,4 +610,19 @@ public final class TestBugs {
             inputStream.close();
         }
     }
+    
+    @Test
+    public void bug56240() throws Exception {
+        InputStream inputStream = new FileInputStream(_slTests.getFile("bug56240.ppt"));
+        try {
+            SlideShow slideShow = new SlideShow(inputStream);
+            int slideCnt = slideShow.getSlides().length;
+            assertEquals(105, slideCnt);
+            ByteArrayOutputStream bos = new ByteArrayOutputStream();
+            slideShow.write(bos);
+            bos.close();
+        } finally {
+            inputStream.close();
+        }
+    }
 }