If we have a picture of type 0, don't even bother trying to create a PictureData object for it

git-svn-id: https://svn.apache.org/repos/asf/jakarta/poi/trunk@487181 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -255,22 +255,27 @@ public class HSLFSlideShow extends POIDocument
         List p = new ArrayList();
         int pos = 0;
 
-        while (pos < pictstream.length) {
+		// An empty picture record (length 0) will take up 8 bytes
+        while (pos <= (pictstream.length-8)) {
             int offset = pos;
 
-            //image signature
+            // Image signature
             int signature = LittleEndian.getUShort(pictstream, pos);
             pos += LittleEndian.SHORT_SIZE;
-            //image type + 0xF018
+            // Image type + 0xF018
             int type = LittleEndian.getUShort(pictstream, pos);
             pos += LittleEndian.SHORT_SIZE;
-            //image size
+            // Image size (excluding the 8 byte header)
             int imgsize = LittleEndian.getInt(pictstream, pos);
             pos += LittleEndian.INT_SIZE;
-
             byte[] imgdata = new byte[imgsize];
             System.arraycopy(pictstream, pos, imgdata, 0, imgdata.length);
 
+			// If they type (including the bonus 0xF018) is 0, skip it
+			if(type == 0) {
+				System.err.println("Problem reading picture: Invalid image type 0, on picture with length" + imgsize + ".\nYou document will probably become corrupted if you save it!");
+			} else {
+				// Build the PictureData object from the data
 				try {
 					PictureData pict = PictureData.create(type - 0xF018);
 					pict.setRawData(imgdata);
@@ -279,6 +284,7 @@ public class HSLFSlideShow extends POIDocument
 				} catch(IllegalArgumentException e) {
 					System.err.println("Problem reading picture: " + e + "\nYou document will probably become corrupted if you save it!");
 				}
+			}
             
             pos += imgsize;
         }

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

@@ -373,5 +373,22 @@ public class TestPictures extends TestCase{
 
     }
 
+	/**
+	 * Test that on a party corrupt powerpoint document, which has 
+	 *  crazy pictures of type 0, we do our best.
+	 */
+	public void testZeroPictureType() throws Exception {
+		HSLFSlideShow hslf = new HSLFSlideShow(new File(cwd, "PictureTypeZero.ppt").getPath());
 
+		// Should still have 2 real pictures
+		assertEquals(2, hslf.getPictures().length);
+		// Both are real pictures, both WMF
+		assertEquals(Picture.WMF, hslf.getPictures()[0].getType());
+		assertEquals(Picture.WMF, hslf.getPictures()[1].getType());
+
+		// TODO: DISABLED: Pending bug #41176
+
+		// Now test what happens when we use the SlideShow interface
+		//SlideShow ppt = new SlideShow(hslf);
+	}
 }