| /* |
| * Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| package sun.jvm.hotspot.utilities; |
| |
| import java.util.*; |
| import sun.jvm.hotspot.debugger.*; |
| import sun.jvm.hotspot.memory.*; |
| import sun.jvm.hotspot.oops.Metadata; |
| import sun.jvm.hotspot.oops.Klass; |
| import sun.jvm.hotspot.runtime.*; |
| import sun.jvm.hotspot.types.*; |
| |
| /** This class determines to the best of its ability, and in a |
| reasonably robust fashion, whether a given pointer is an intact |
| oop or not. It does this by checking the integrity of the |
| metaclass hierarchy. This is only intended for use in the |
| debugging system. It may provide more resilience to unexpected VM |
| states than the ObjectHeap code. */ |
| |
| public class RobustOopDeterminator { |
| private static AddressField klassField; |
| |
| static { |
| VM.registerVMInitializedObserver(new Observer() { |
| public void update(Observable o, Object data) { |
| initialize(VM.getVM().getTypeDataBase()); |
| } |
| }); |
| } |
| |
| private static void initialize(TypeDataBase db) { |
| Type type = db.lookupType("oopDesc"); |
| |
| if (VM.getVM().isCompressedKlassPointersEnabled()) { |
| klassField = type.getAddressField("_metadata._compressed_klass"); |
| } else { |
| klassField = type.getAddressField("_metadata._klass"); |
| } |
| } |
| |
| public static boolean oopLooksValid(OopHandle oop) { |
| if (oop == null) { |
| return false; |
| } |
| if (!VM.getVM().getUniverse().isIn(oop)) { |
| return false; |
| } |
| try { |
| // Try to instantiate the Klass |
| if (VM.getVM().isCompressedKlassPointersEnabled()) { |
| Metadata.instantiateWrapperFor(oop.getCompKlassAddressAt(klassField.getOffset())); |
| } else { |
| Metadata.instantiateWrapperFor(klassField.getValue(oop)); |
| } |
| return true; |
| } |
| catch (AddressException e) { |
| return false; |
| } |
| } |
| } |