1 /*
   2  * Copyright (c) 2000, 2005, 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.runtime;
  26 
  27 import java.util.*;
  28 import sun.jvm.hotspot.debugger.*;
  29 import sun.jvm.hotspot.debugger.cdbg.*;
  30 import sun.jvm.hotspot.types.*;
  31 
  32 /** This class provides generalized "virtual constructor"
  33     functionality for VMObjects. In simple terms, it creates
  34     correctly-typed Java wrapper objects for underlying Addresses,
  35     using the "RTTI-like" functionality of TypeDataBase. For example,
  36     if the given Address really is a DefNewGeneration*, the Java object
  37     created for it will be of type
  38     sun.jvm.hotspot.memory.DefNewGeneration, assuming the mapping from
  39     type "DefNewGeneration" to class
  40     sun.jvm.hotspot.memory.DefNewGeneration has been set up. */
  41 
  42 public class VirtualConstructor {
  43   private TypeDataBase db;
  44   private Map          map; // Map<String, Class>
  45 
  46   public VirtualConstructor(TypeDataBase db) {
  47     this.db = db;
  48     map     = new HashMap();
  49   }
  50 
  51   /** Adds a mapping from the given C++ type name to the given Java
  52       class. The latter must be a subclass of
  53       sun.jvm.hotspot.runtime.VMObject. Returns false if there was
  54       already a class for this type name in the map. */
  55   public boolean addMapping(String cTypeName, Class clazz) {
  56     if (map.get(cTypeName) != null) {
  57       return false;
  58     }
  59 
  60     map.put(cTypeName, clazz);
  61     return true;
  62   }
  63 
  64   /** Instantiate the most-precisely typed wrapper object available
  65       for the type of the given Address. If no type in the mapping
  66       matched the type of the Address, throws a WrongTypeException.
  67       Returns null for a null address (similar behavior to
  68       VMObjectFactory). */
  69   public VMObject instantiateWrapperFor(Address addr) throws WrongTypeException {
  70     if (addr == null) {
  71       return null;
  72     }
  73 
  74     for (Iterator iter = map.keySet().iterator(); iter.hasNext(); ) {
  75       String typeName = (String) iter.next();
  76       if (db.addressTypeIsEqualToType(addr, db.lookupType(typeName))) {
  77         return (VMObject) VMObjectFactory.newObject((Class) map.get(typeName), addr);
  78       }
  79     }
  80 
  81     String message = "No suitable match for type of address " + addr;
  82     CDebugger cdbg = VM.getVM().getDebugger().getCDebugger();
  83     if (cdbg != null) {
  84       // Most common case: V-table pointer is the first field
  85       Address vtblPtr = addr.getAddressAt(0);
  86       LoadObject lo = cdbg.loadObjectContainingPC(vtblPtr);
  87       if (lo != null) {
  88         ClosestSymbol symbol = lo.closestSymbolToPC(vtblPtr);
  89         if (symbol != null) {
  90           message += " (nearest symbol is " + symbol.getName() + ")";
  91         }
  92       }
  93     }
  94 
  95     throw new WrongTypeException(message);
  96   }
  97 }