Bug 66425: Avoid a ClassCastException found via oss-fuzz

We try to avoid throwing ClassCastException, but it was possible
to trigger one here with a specially crafted input-file

Should fix https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=61259

Also fix handling of NullPointerException

git-svn-id: https://svn.apache.org/repos/asf/poi/trunk@1911517 13f79535-47bb-0310-9956-ffa450edef68

poi-integration/src/test/java/org/apache/poi/stress/TestAllFiles.java

@@ -253,13 +253,22 @@ public class TestAllFiles {
             Exception e = assertThrows((Class<? extends Exception>)exClass, exec, errPrefix + " expected " + exClass);
             String actMsg = pathReplace(e.getMessage());
 
-            // verify that message is either null for both or set for both
-            assertTrue(actMsg != null || StringUtils.isBlank(exMessage),
-                    errPrefix + " for " + exClass + " expected message '" + exMessage + "' but had '" + actMsg + "'");
+            // perform special handling of NullPointerException as
+            // JDK started to add more information in some newer JDK, so
+            // it sometimes has a message and sometimes not!
+            if (NullPointerException.class.isAssignableFrom(exClass)) {
+                if (actMsg != null) {
+                    assertTrue(actMsg.contains(exMessage), errPrefix + "Message: "+actMsg+" - didn't contain: "+exMessage);
+                }
+            } else {
+                // verify that message is either null for both or set for both
+                assertTrue(actMsg != null || StringUtils.isBlank(exMessage),
+                        errPrefix + " for " + exClass + " expected message '" + exMessage + "' but had '" + actMsg + "'");
 
-            if (actMsg != null) {
-                assertTrue(actMsg.contains(exMessage),
-                        errPrefix + "Message: " + actMsg + " - didn't contain: " + exMessage);
+                if (actMsg != null) {
+                    assertTrue(actMsg.contains(exMessage),
+                            errPrefix + "Message: " + actMsg + " - didn't contain: " + exMessage);
+                }
             }
         } else {
             assertDoesNotThrow(exec, errPrefix);

poi-scratchpad/src/main/java/org/apache/poi/hslf/usermodel/HSLFSlideShowImpl.java

@@ -72,6 +72,7 @@ import org.apache.poi.poifs.crypt.EncryptionInfo;
 import org.apache.poi.poifs.filesystem.DirectoryNode;
 import org.apache.poi.poifs.filesystem.DocumentEntry;
 import org.apache.poi.poifs.filesystem.DocumentInputStream;
+import org.apache.poi.poifs.filesystem.Entry;
 import org.apache.poi.poifs.filesystem.EntryUtils;
 import org.apache.poi.poifs.filesystem.POIFSFileSystem;
 import org.apache.poi.sl.usermodel.PictureData;
@@ -229,7 +230,11 @@ public final class HSLFSlideShowImpl extends POIDocument implements Closeable {
         }
 
         // Get the main document stream
-        DocumentEntry docProps = (DocumentEntry)dir.getEntry(POWERPOINT_DOCUMENT);
+        final Entry entry = dir.getEntry(POWERPOINT_DOCUMENT);
+        if (!(entry instanceof DocumentEntry)) {
+            throw new IllegalArgumentException("Had unexpected type of entry for name: " + POWERPOINT_DOCUMENT + ": " + entry.getClass());
+        }
+        DocumentEntry docProps = (DocumentEntry) entry;
 
         // Grab the document stream
         int len = docProps.getSize();