opcodestack.java

A static analysis tool to find bugs in Java programs

				 case IASTORE:
				 case LASTORE:
				 case SASTORE:
					 pop(3);
				 break;

				 case BIPUSH:
				 case SIPUSH:
					 push(new Item("I", (Integer)dbc.getIntConstant()));
				 break;

				 case IADD:
				 case ISUB:
				 case IMUL:
				 case IDIV:
				 case IAND:
				 case IOR:
				 case IXOR:
				 case ISHL:
				 case ISHR:
				 case IREM:
				 case IUSHR:
					 it = pop();
					 it2 = pop();
					 pushByIntMath(seen, it2, it);
				 break;

				 case INEG:
					 it = pop();
					 if (it.getConstant() != null) {
						 push(new Item("I", ( Integer)(-(Integer) it.getConstant())));
					 } else {
						 push(new Item("I"));
					 }
				 break;

				 case LNEG:
					 it = pop();
					 if (it.getConstant() != null) {
						 push(new Item("J", ( Long)(-(Long) it.getConstant())));
					 } else {
						 push(new Item("J"));
					 }
				 break;

				 case DNEG:
					 it = pop();
					 if (it.getConstant() != null) {
						 push(new Item("D", ( Double)(-(Double) it.getConstant())));
					 } else {
						 push(new Item("D"));
					 }
				 break;

				 case LADD:
				 case LSUB:
				 case LMUL:
				 case LDIV:
				 case LAND:
				 case LOR:
				 case LXOR:
				 case LSHL:
				 case LSHR:
				 case LREM:
				 case LUSHR:

					 it = pop();
					 it2 = pop();
					 pushByLongMath(seen, it2, it);	 				
				 break;

				 case LCMP:
				 handleLcmp();
				 break;

				 case FCMPG:
				 case FCMPL: handleFcmp(seen);
				 break;

				 case DCMPG:
				 case DCMPL:
					 handleDcmp(seen);
				 break;

				 case FADD:
				 case FSUB:
				 case FMUL:
				 case FDIV:
					 it = pop();
					 it2 = pop();
					 pushByFloatMath(seen, it, it2);
				 break;

				 case DADD:
				 case DSUB:
				 case DMUL:
				 case DDIV:
				 case DREM:
					 it = pop();
					 it2 = pop();
					 pushByDoubleMath(seen, it, it2);
				 break;

				 case I2B:
					 it = pop();
					 if (it.getConstant() != null) {
						 it =new Item("I", (byte)constantToInt(it));
					 } else {
						 it = new Item("I");
					 }
					 it.setSpecialKind(Item.SIGNED_BYTE);
					 push(it);
				 break;

				 case I2C:
					 it = pop();
					 if (it.getConstant() != null) {
						it = new Item("I", (char)constantToInt(it));
					 } else {
						it = new Item("I");
					 }
					it.setSpecialKind(Item.MASKED_NON_NEGATIVE);
					push(it);
				 break;

				 case I2L:
				 case D2L:{
					 it = pop();
					 Item newValue;
					 if (it.getConstant() != null) {
						 newValue = new Item("J", constantToLong(it));
					 } else {
						 newValue = new Item("J");
					 }
					 newValue.setSpecialKind(it.getSpecialKind());
					 push(newValue);
				 }
				 break;

				 case I2S:
					 it = pop();
					 if (it.getConstant() != null) {
						 push(new Item("I", (short)constantToInt(it)));
					 } else {
						 push(new Item("I"));
					 }
				 break;

				 case L2I:
				 case D2I:
				 case F2I:
					 it = pop();
					 if (it.getConstant() != null) {
						 push(new Item("I",constantToInt(it)));
					 } else {
						 push(new Item("I"));
					 }
				 break;

				 case L2F:
				 case D2F:
				 case I2F:
					 it = pop();
					 if (it.getConstant() != null) {
						 push(new Item("F", (Float)(constantToFloat(it))));
					 } else {
						 push(new Item("F"));
					 }
				 break;

				 case F2D:
				 case I2D:
				 case L2D:
					 it = pop();
					 if (it.getConstant() != null) {
						 push(new Item("D", constantToDouble(it)));
					 } else {
						 push(new Item("D"));
					 }
				 break;

				 case NEW:
					 pushBySignature("L" + dbc.getClassConstantOperand() + ";");
				 break;

				 case NEWARRAY:
					 pop();
					 signature = "[" + BasicType.getType((byte)dbc.getIntConstant()).getSignature();
					 pushBySignature(signature);
				 break;

				// According to the VM Spec 4.4.1, anewarray and multianewarray
				// can refer to normal class/interface types (encoded in
				// "internal form"), or array classes (encoded as signatures
				// beginning with "[").

				 case ANEWARRAY:
					 pop();
					signature = dbc.getClassConstantOperand();
					if (!signature.startsWith("[")) {
						signature = "[L" + signature + ";";
					}
					 pushBySignature(signature);
				 break;

				 case MULTIANEWARRAY:
					 int dims = dbc.getIntConstant();
					 while ((dims--) > 0) {
						 pop();
					 }
					signature = dbc.getClassConstantOperand();
					if (!signature.startsWith("[")) {
						dims = dbc.getIntConstant();
						signature = "";
						while ((dims--) > 0)
							signature += "[";
						signature += "L" + signature + ";";
					}
					pushBySignature(signature);
				 break;

				 case AALOAD:
					 pop();
					 it = pop();
					 pushBySignature(it.getElementSignature());
				 break;

				 case JSR:
					 push(new Item("")); //?
				 break;

				case INVOKEINTERFACE:
				 case INVOKESPECIAL:
				 case INVOKESTATIC:
				 case INVOKEVIRTUAL:
					 processMethodCall(dbc, seen);
				 break;

				 default:
					 throw new UnsupportedOperationException("OpCode " + OPCODE_NAMES[seen] + " not supported " );
			 }
		 }

		 catch (RuntimeException e) {
			 //If an error occurs, we clear the stack and locals. one of two things will occur. 
			 //Either the client will expect more stack items than really exist, and so they're condition check will fail, 
			 //or the stack will resync with the code. But hopefully not false positives
			 // TODO: log this
			 if (DEBUG) 
				 e.printStackTrace();
			 clear();
		 }
		 finally {
			 if (exceptionHandlers.get(dbc.getNextPC()))
				 push(new Item());
			 if (DEBUG) {
				 System.out.println(dbc.getNextPC() + "pc : " + OPCODE_NAMES[seen] + "  stack depth: " + getStackDepth());
				 System.out.println(this);
			 }
		 }
	 }

	/**
	 * @param it
	 * @return
	 */
	private int constantToInt(Item it) {
		return ((Number)it.getConstant()).intValue();
	}

	/**
	 * @param it
	 * @return
	 */
	private float constantToFloat(Item it) {
		return ((Number)it.getConstant()).floatValue();
	}

	/**
	 * @param it
	 * @return
	 */
	private double constantToDouble(Item it) {
		return ((Number)it.getConstant()).doubleValue();
	}

	/**
	 * @param it
	 * @return
	 */
	private long constantToLong(Item it) {
		return ((Number)it.getConstant()).longValue();
	}

	/**
	 * @param opcode TODO
	 * 
	 */
	private void handleDcmp(int opcode) {
		Item it;
		Item it2;

		it = pop();

		it2 = pop();
		if ((it.getConstant() != null) && it2.getConstant() != null) {
			double d = (Double) it.getConstant();
			double d2 = (Double) it.getConstant();
			if (Double.isNaN(d) || Double.isNaN(d2)) {
				if (opcode == DCMPG)
					push(new Item("I", (Integer)(1)));
				else 
					push(new Item("I", (Integer)(-1)));
			}
			if (d2 < d)
				push(new Item("I", (Integer) (-1) ));
			else if (d2 > d)
				push(new Item("I", (Integer)1));
			else
				push(new Item("I", (Integer)0));
		} else {
			push(new Item("I"));
		}

	}

	/**
	 * @param opcode TODO
	 * 
	 */
	private void handleFcmp(int opcode) {
		Item it;
		Item it2;
			it = pop();
			it2 = pop();
			if ((it.getConstant() != null) && it2.getConstant() != null) {
				float f = (Float) it.getConstant();
				float f2 = (Float) it.getConstant();
				if (Float.isNaN(f) || Float.isNaN(f2)) {
					if (opcode == FCMPG)
						push(new Item("I", (Integer)(1)));
					else 
						push(new Item("I", (Integer)(-1)));
				}
				if (f2 < f)
					push(new Item("I", (Integer)(-1)));
				else if (f2 > f)
					push(new Item("I", (Integer)(1)));
				else
					push(new Item("I", (Integer)(0)));
			} else {
				push(new Item("I"));
			}
	}

	/**
	 * 
	 */
	private void handleLcmp() {
		Item it;
		Item it2;

			it = pop();
			it2 = pop();
			if ((it.getConstant() != null) && it2.getConstant() != null) {
				long l = (Long) it.getConstant();
				long l2 = (Long) it.getConstant();
				if (l2 < l)
					push(new Item("I", (Integer)(-1)));
				else if (l2 > l)
					push(new Item("I", (Integer)(1)));
				else
					push(new Item("I", (Integer)(0)));
			} else {
				push(new Item("I"));
			}

	}

	/**
	 * 
	 */
	private void handleSwap() {
		Item i1 = pop();
		Item i2 = pop();
		push(i1);
		push(i2);
	}

	/**
	 * 
	 */
	private void handleDup() {
		Item it;
		it = pop();
		push(it);
		push(it);
	}

	/**
	 * 
	 */
	private void handleDupX1() {
		Item it;
		Item it2;
			it = pop();
			it2 = pop();
			push(it);
			push(it2);
			push(it);
	}

	/**
	 * 
	 */
	private void handleDup2() {
		Item it, it2;
		it = pop();
		if  (it.getSize() == 2) {
			push(it);
			push(it);
		}
		else {
			it2 = pop();
			push(it2);
			push(it);
			push(it2);
			push(it);
		}
	}

	/**
	 * 
	 */
	private void handleDup2X1() {
		String signature;
		Item it;
		Item it2;
		Item it3;

		it = pop();

	it2 = pop();
	signature = it.getSignature();
	if (signature.equals("J") || signature.equals("D")) {
		push(it);
		push(it2);
		push(it);	 				
	} else {
		it3 = pop();
		push(it2);
		push(it);
		push(it3);
		push(it2);
		push(it);
	}
	}

	/**
	 * 
	 */
	private void handleDupX2() {
		String signature;
		Item it;
		Item it2;
		Item it3;
		it = pop();
		it2 = pop();
		signature = it2.getSignature();
		if (signature.equals("J") || signature.equals("D")) {
			push(it);
			push(it2);
			push(it);	 				
		} else {
			it3 = pop();
			push(it);
			push(it3);
			push(it2);
			push(it);
		}
	}

	private void processMethodCall(DismantleBytecode dbc, int seen) {
		 String clsName = dbc.getClassConstantOperand();
		 String methodName = dbc.getNameConstantOperand();
		 String signature = dbc.getSigConstantOperand();
		 String appenderValue = null;
		 Item sbItem = null;

		 //TODO: stack merging for trinaries kills the constant.. would be nice to maintain.
		 if ("java/lang/StringBuffer".equals(clsName)
		 ||  "java/lang/StringBuilder".equals(clsName)) {
			 if ("<init>".equals(methodName)) {
				 if ("(Ljava/lang/String;)V".equals(signature)) {
					 Item i = getStackItem(0);
					 appenderValue = (String)i.getConstant();
				 } else if ("()V".equals(signature)) {
					 appenderValue = "";
				 }
			 } else if ("toString".equals(methodName)) {
				 Item i = getStackItem(0);
				 appenderValue = (String)i.getConstant();
			 } else if ("append".equals(methodName) && signature.indexOf("II)") == -1) {
				 sbItem = getStackItem(1);
				 Item i = getStackItem(0);
				 Object sbVal = sbItem.getConstant();