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 
  33 public class ClassLoaderData extends VMObject {
  34   static {
  35     VM.registerVMInitializedObserver(new java.util.Observer() {
  36         public void update(java.util.Observable o, Object data) {
  37           initialize(VM.getVM().getTypeDataBase());
  38         }
  39       });
  40   }
  41 
  42   private static synchronized void initialize(TypeDataBase db) throws WrongTypeException {
  43     Type type      = db.lookupType("ClassLoaderData");
  44     classLoaderFieldOffset = type.getAddressField("_class_loader").getOffset();
  45     nextField = type.getAddressField("_next");
  46     klassesField = new MetadataField(type.getAddressField("_klasses"), 0);
  47     dictionaryField = type.getAddressField("_dictionary");
  48   }
  49 
  50   private static long classLoaderFieldOffset;
  51   private static AddressField nextField;
  52   private static MetadataField  klassesField;
  53   private static AddressField dictionaryField;
  54 
  55   public ClassLoaderData(Address addr) {
  56     super(addr);
  57   }
  58 
  59   public Dictionary dictionary() {
  60       Address tmp = dictionaryField.getValue();
  61       return (Dictionary) VMObjectFactory.newObject(Dictionary.class, tmp);
  62   }
  63 
  64   public static ClassLoaderData instantiateWrapperFor(Address addr) {
  65     if (addr == null) {
  66       return null;
  67     }
  68     return new ClassLoaderData(addr);
  69   }
  70 
  71   public Oop getClassLoader() {
  72     Address addr = getAddress().addOffsetTo(classLoaderFieldOffset);
  73     VMOopHandle vmOopHandle = VMObjectFactory.newObject(VMOopHandle.class, addr);
  74     return vmOopHandle.resolve();
  75   }
  76 
  77   public ClassLoaderData next() {
  78     return instantiateWrapperFor(nextField.getValue(getAddress()));
  79   }
  80 
  81   public Klass getKlasses()    { return (Klass)klassesField.getValue(this);  }
  82 
  83   /** Lookup an already loaded class. If not found null is returned. */
  84   public Klass find(String className) {
  85     for (Klass l = getKlasses(); l != null; l = l.getNextLinkKlass()) {
  86         if (l.getName().equals(className)) {
  87             return l;
  88         }
  89     }
  90     return null;
  91   }
  92 
  93   /** Iterate over all klasses - including object, primitive
  94       array klasses */
  95   public void classesDo(ClassLoaderDataGraph.ClassVisitor v) {
  96       for (Klass l = getKlasses(); l != null; l = l.getNextLinkKlass()) {
  97           v.visit(l);
  98       }
  99   }
 100 
 101   /** Iterate over all klasses in the dictionary, including initiating loader. */
 102   public void allEntriesDo(ClassLoaderDataGraph.ClassAndLoaderVisitor v) {
 103       for (Klass l = getKlasses(); l != null; l = l.getNextLinkKlass()) {
 104           dictionary().allEntriesDo(v, getClassLoader());
 105       }
 106   }
 107 }