1 /*
   2  * Copyright (c) 2012, 2020, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 package sun.jvm.hotspot.classfile;
  26 
  27 import sun.jvm.hotspot.debugger.*;
  28 import sun.jvm.hotspot.memory.*;
  29 import sun.jvm.hotspot.runtime.*;
  30 import sun.jvm.hotspot.oops.*;
  31 import sun.jvm.hotspot.types.*;
  32 import sun.jvm.hotspot.utilities.Observable;
  33 import sun.jvm.hotspot.utilities.Observer;
  34 
  35 public class ClassLoaderData extends VMObject {
  36   static {
  37     VM.registerVMInitializedObserver(new Observer() {
  38         public void update(Observable o, Object data) {
  39           initialize(VM.getVM().getTypeDataBase());
  40         }
  41       });
  42   }
  43 
  44   private static synchronized void initialize(TypeDataBase db) throws WrongTypeException {
  45     Type type      = db.lookupType("ClassLoaderData");
  46     classLoaderFieldOffset = type.getAddressField("_class_loader").getOffset();
  47     nextField = type.getAddressField("_next");
  48     klassesField = new MetadataField(type.getAddressField("_klasses"), 0);
  49     dictionaryField = type.getAddressField("_dictionary");
  50   }
  51 
  52   private static long classLoaderFieldOffset;
  53   private static AddressField nextField;
  54   private static MetadataField  klassesField;
  55   private static AddressField dictionaryField;
  56 
  57   public ClassLoaderData(Address addr) {
  58     super(addr);
  59   }
  60 
  61   public Dictionary dictionary() {
  62       Address tmp = dictionaryField.getValue();
  63       return (Dictionary) VMObjectFactory.newObject(Dictionary.class, tmp);
  64   }
  65 
  66   public static ClassLoaderData instantiateWrapperFor(Address addr) {
  67     if (addr == null) {
  68       return null;
  69     }
  70     return new ClassLoaderData(addr);
  71   }
  72 
  73   public Oop getClassLoader() {
  74     Address addr = getAddress().addOffsetTo(classLoaderFieldOffset);
  75     VMOopHandle vmOopHandle = VMObjectFactory.newObject(VMOopHandle.class, addr);
  76     return vmOopHandle.resolve();
  77   }
  78 
  79   public ClassLoaderData next() {
  80     return instantiateWrapperFor(nextField.getValue(getAddress()));
  81   }
  82 
  83   public Klass getKlasses()    { return (Klass)klassesField.getValue(this);  }
  84 
  85   /** Lookup an already loaded class. If not found null is returned. */
  86   public Klass find(String className) {
  87     for (Klass l = getKlasses(); l != null; l = l.getNextLinkKlass()) {
  88         if (l.getName().equals(className)) {
  89             return l;
  90         }
  91     }
  92     return null;
  93   }
  94 
  95   /** Iterate over all klasses - including object, primitive
  96       array klasses */
  97   public void classesDo(ClassLoaderDataGraph.ClassVisitor v) {
  98       for (Klass l = getKlasses(); l != null; l = l.getNextLinkKlass()) {
  99           v.visit(l);
 100       }
 101   }
 102 
 103   /** Iterate over all klasses in the dictionary, including initiating loader. */
 104   public void allEntriesDo(ClassLoaderDataGraph.ClassAndLoaderVisitor v) {
 105       for (Klass l = getKlasses(); l != null; l = l.getNextLinkKlass()) {
 106           dictionary().allEntriesDo(v, getClassLoader());
 107       }
 108   }
 109 }