示例#1
0
 /*  94:    */
 /*  95:    */ protected int match(
     int c, int pos, CodeIterator iterator, int typedesc, ConstPool cp)
     /*  96:    */ throws BadBytecode
       /*  97:    */ {
   /*  98:110 */ if (this.newIndex == 0)
   /*  99:    */ {
     /* 100:111 */ int nt = cp.addNameAndTypeInfo(cp.addUtf8Info(this.newMethodname), typedesc);
     /* 101:    */
     /* 102:113 */ int ci = cp.addClassInfo(this.newClassname);
     /* 103:114 */ if (c == 185)
     /* 104:    */ {
       /* 105:115 */ this.newIndex = cp.addInterfaceMethodrefInfo(ci, nt);
       /* 106:    */ }
     /* 107:    */ else
     /* 108:    */ {
       /* 109:117 */ if ((this.newMethodIsPrivate) && (c == 182)) {
         /* 110:118 */ iterator.writeByte(183, pos);
         /* 111:    */ }
       /* 112:120 */ this.newIndex = cp.addMethodrefInfo(ci, nt);
       /* 113:    */ }
     /* 114:123 */ this.constPool = cp;
     /* 115:    */ }
   /* 116:126 */ iterator.write16bit(this.newIndex, pos + 1);
   /* 117:127 */ return pos;
   /* 118:    */ }
  public boolean transformClass(ClassFile file, ClassLoader loader, boolean modifiableClass) {
    Set<Integer> methodCallLocations = new HashSet<Integer>();
    Integer newCallLocation = null;
    Integer methodReflectionLocation = null;
    Integer fakeCallRequiredLocation = null;
    // first we need to scan the constant pool looking for
    // CONSTANT_method_info_ref structures
    ConstPool pool = file.getConstPool();
    for (int i = 1; i < pool.getSize(); ++i) {
      // we have a method call
      if (pool.getTag(i) == ConstPool.CONST_Methodref) {
        String className = pool.getMethodrefClassName(i);
        String methodName = pool.getMethodrefName(i);

        if (className.equals(Method.class.getName())) {
          if (methodName.equals("invoke")) {
            // store the location in the const pool of the method ref
            methodCallLocations.add(i);
            // we have found a method call

            // if we have not already stored a reference to our new
            // method in the const pool
            if (newCallLocation == null) {
              methodReflectionLocation =
                  pool.addClassInfo("org.fakereplace.reflection.MethodReflection");
              int nt = pool.addNameAndTypeInfo("fakeCallRequired", "(Ljava/lang/reflect/Method;)Z");
              fakeCallRequiredLocation = pool.addMethodrefInfo(methodReflectionLocation, nt);
              newCallLocation = pool.addNameAndTypeInfo(METHOD_NAME, REPLACED_METHOD_DESCRIPTOR);
            }
          }
        }
      }
    }

    // this means we found an instance of the call, now we have to iterate
    // through the methods and replace instances of the call
    if (newCallLocation != null) {
      List<MethodInfo> methods = file.getMethods();
      for (MethodInfo m : methods) {
        try {
          // ignore abstract methods
          if (m.getCodeAttribute() == null) {
            continue;
          }
          CodeIterator it = m.getCodeAttribute().iterator();
          while (it.hasNext()) {
            // loop through the bytecode
            int index = it.next();
            int op = it.byteAt(index);
            // if the bytecode is a method invocation
            if (op == CodeIterator.INVOKEVIRTUAL) {
              int val = it.s16bitAt(index + 1);
              // if the method call is one of the methods we are
              // replacing
              if (methodCallLocations.contains(val)) {
                Bytecode b = new Bytecode(file.getConstPool());
                // our stack looks like Method, instance,params
                // we need Method, instance, params , Method
                b.add(Opcode.DUP_X2);
                b.add(Opcode.POP);
                b.add(Opcode.DUP_X2);
                b.add(Opcode.POP);
                b.add(Opcode.DUP_X2);
                b.addInvokestatic(
                    methodReflectionLocation, "fakeCallRequired", "(Ljava/lang/reflect/Method;)Z");
                b.add(Opcode.IFEQ);
                JumpMarker performRealCall = JumpUtils.addJumpInstruction(b);
                // now perform the fake call
                b.addInvokestatic(methodReflectionLocation, "invoke", REPLACED_METHOD_DESCRIPTOR);
                b.add(Opcode.GOTO);
                JumpMarker finish = JumpUtils.addJumpInstruction(b);
                performRealCall.mark();
                b.addInvokevirtual(Method.class.getName(), METHOD_NAME, METHOD_DESCRIPTOR);
                finish.mark();
                it.writeByte(CodeIterator.NOP, index);
                it.writeByte(CodeIterator.NOP, index + 1);
                it.writeByte(CodeIterator.NOP, index + 2);
                it.insert(b.get());
              }
            }
          }
          m.getCodeAttribute().computeMaxStack();
        } catch (Exception e) {
          log.error("Bad byte code transforming " + file.getName());
          e.printStackTrace();
        }
      }
      return true;
    } else {
      return false;
    }
  }
  /**
   * Replace access to fields of entities (for example, entity.field) with a call to the enhanced
   * getter / setter (in this example, entity.$$_hibernate_read_field()). It's assumed that the
   * target entity is enhanced as well.
   *
   * @param managedCtClass Class to enhance
   */
  public void enhanceFieldAccess(CtClass managedCtClass) {
    final ConstPool constPool = managedCtClass.getClassFile().getConstPool();

    for (Object oMethod : managedCtClass.getClassFile().getMethods()) {
      final MethodInfo methodInfo = (MethodInfo) oMethod;
      final String methodName = methodInfo.getName();

      // skip methods added by enhancement and abstract methods (methods without any code)
      if (methodName.startsWith("$$_hibernate_") || methodInfo.getCodeAttribute() == null) {
        continue;
      }

      try {
        final CodeIterator itr = methodInfo.getCodeAttribute().iterator();
        while (itr.hasNext()) {
          int index = itr.next();
          int op = itr.byteAt(index);
          if (op != Opcode.PUTFIELD && op != Opcode.GETFIELD) {
            continue;
          }
          String fieldName = constPool.getFieldrefName(itr.u16bitAt(index + 1));
          String fieldClassName =
              constPool.getClassInfo(constPool.getFieldrefClass(itr.u16bitAt(index + 1)));
          CtClass targetCtClass = this.classPool.getCtClass(fieldClassName);

          if (!enhancementContext.isEntityClass(targetCtClass)
              && !enhancementContext.isCompositeClass(targetCtClass)) {
            continue;
          }
          if (targetCtClass == managedCtClass
              || !enhancementContext.isPersistentField(targetCtClass.getField(fieldName))
              || "this$0".equals(fieldName)) {
            continue;
          }

          log.debugf("Transforming access to field [%s] from method [%s]", fieldName, methodName);

          if (op == Opcode.GETFIELD) {
            int fieldReaderMethodIndex =
                constPool.addMethodrefInfo(
                    constPool.addClassInfo(fieldClassName),
                    EnhancerConstants.PERSISTENT_FIELD_READER_PREFIX + fieldName,
                    "()" + constPool.getFieldrefType(itr.u16bitAt(index + 1)));
            itr.writeByte(Opcode.INVOKEVIRTUAL, index);
            itr.write16bit(fieldReaderMethodIndex, index + 1);
          } else {
            int fieldWriterMethodIndex =
                constPool.addMethodrefInfo(
                    constPool.addClassInfo(fieldClassName),
                    EnhancerConstants.PERSISTENT_FIELD_WRITER_PREFIX + fieldName,
                    "(" + constPool.getFieldrefType(itr.u16bitAt(index + 1)) + ")V");
            itr.writeByte(Opcode.INVOKEVIRTUAL, index);
            itr.write16bit(fieldWriterMethodIndex, index + 1);
          }
        }
        methodInfo.getCodeAttribute().setAttribute(MapMaker.make(classPool, methodInfo));
      } catch (BadBytecode bb) {
        final String msg =
            String.format(
                "Unable to perform field access transformation in method [%s]", methodName);
        throw new EnhancementException(msg, bb);
      } catch (NotFoundException nfe) {
        final String msg =
            String.format(
                "Unable to perform field access transformation in method [%s]", methodName);
        throw new EnhancementException(msg, nfe);
      }
    }
  }