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     hasClassMirrorHolderField = new CIntField(type.getCIntegerField("_has_class_mirror_holder"), 0);
  50     dictionaryField = type.getAddressField("_dictionary");
  51   }
  52 
  53   private static long classLoaderFieldOffset;
  54   private static AddressField nextField;
  55   private static MetadataField  klassesField;
  56   private static CIntField hasClassMirrorHolderField;
  57   private static AddressField dictionaryField;
  58 
  59   public ClassLoaderData(Address addr) {
  60     super(addr);
  61   }
  62 
  63   public Dictionary dictionary() {
  64       Address tmp = dictionaryField.getValue();
  65       return (Dictionary) VMObjectFactory.newObject(Dictionary.class, tmp);
  66   }
  67 
  68   public static ClassLoaderData instantiateWrapperFor(Address addr) {
  69     if (addr == null) {
  70       return null;
  71     }
  72     return new ClassLoaderData(addr);
  73   }
  74 
  75   public Oop getClassLoader() {
  76     Address addr = getAddress().addOffsetTo(classLoaderFieldOffset);
  77     VMOopHandle vmOopHandle = VMObjectFactory.newObject(VMOopHandle.class, addr);
  78     return vmOopHandle.resolve();
  79   }
  80 
  81   public boolean gethasClassMirrorHolder() {
  82     return hasClassMirrorHolderField.getValue(this) != 0;
  83   }
  84 
  85   public ClassLoaderData next() {
  86     return instantiateWrapperFor(nextField.getValue(getAddress()));
  87   }
  88 
  89   public Klass getKlasses()    { return (Klass)klassesField.getValue(this);  }
  90 
  91   /** Lookup an already loaded class. If not found null is returned. */
  92   public Klass find(String className) {
  93     for (Klass l = getKlasses(); l != null; l = l.getNextLinkKlass()) {
  94         if (l.getName().equals(className)) {
  95             return l;
  96         }
  97     }
  98     return null;
  99   }
 100 
 101   /** Iterate over all klasses - including object, primitive
 102       array klasses */
 103   public void classesDo(ClassLoaderDataGraph.ClassVisitor v) {
 104       for (Klass l = getKlasses(); l != null; l = l.getNextLinkKlass()) {
 105           v.visit(l);
 106       }
 107   }
 108 
 109   /** Iterate over all klasses in the dictionary, including initiating loader. */
 110   public void allEntriesDo(ClassLoaderDataGraph.ClassAndLoaderVisitor v) {
 111       for (Klass l = getKlasses(); l != null; l = l.getNextLinkKlass()) {
 112           dictionary().allEntriesDo(v, getClassLoader());
 113       }
 114   }
 115 }