ASM: a very small and fast Java bytecode manipulation framework
Copyright (c) 2000-2011 INRIA, France Telecom
All rights reserved.
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modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.
3. Neither the name of the copyright holders nor the names of its
   contributors may be used to endorse or promote products derived from
   this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2011 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.objectweb.asm.tree.analysis;

import java.util.List;

import org.objectweb.asm.Type;
import org.objectweb.asm.tree.AbstractInsnNode;
import org.objectweb.asm.tree.FieldInsnNode;
import org.objectweb.asm.tree.InvokeDynamicInsnNode;
import org.objectweb.asm.tree.MethodInsnNode;

An extended BasicInterpreter that checks that bytecode instructions are correctly used. 
Author:
Eric Bruneton, Bing Ran/**
 * An extended {@link BasicInterpreter} that checks that bytecode instructions
 * are correctly used.
 * 
 * @author Eric Bruneton
 * @author Bing Ran
 */
public class BasicVerifier extends BasicInterpreter {

    public BasicVerifier() {
        super(ASM4);
    }

    protected BasicVerifier(final int api) {
        super(api);
    }

    @Override
    public BasicValue copyOperation(final AbstractInsnNode insn,
            final BasicValue value) throws AnalyzerException {
        Value expected;
        switch (insn.getOpcode()) {
        case ILOAD:
        case ISTORE:
            expected = BasicValue.INT_VALUE;
            break;
        case FLOAD:
        case FSTORE:
            expected = BasicValue.FLOAT_VALUE;
            break;
        case LLOAD:
        case LSTORE:
            expected = BasicValue.LONG_VALUE;
            break;
        case DLOAD:
        case DSTORE:
            expected = BasicValue.DOUBLE_VALUE;
            break;
        case ALOAD:
            if (!value.isReference()) {
                throw new AnalyzerException(insn, null, "an object reference",
                        value);
            }
            return value;
        case ASTORE:
            if (!value.isReference()
                    && !BasicValue.RETURNADDRESS_VALUE.equals(value)) {
                throw new AnalyzerException(insn, null,
                        "an object reference or a return address", value);
            }
            return value;
        default:
            return value;
        }
        if (!expected.equals(value)) {
            throw new AnalyzerException(insn, null, expected, value);
        }
        return value;
    }

    @Override
    public BasicValue unaryOperation(final AbstractInsnNode insn,
            final BasicValue value) throws AnalyzerException {
        BasicValue expected;
        switch (insn.getOpcode()) {
        case INEG:
        case IINC:
        case I2F:
        case I2L:
        case I2D:
        case I2B:
        case I2C:
        case I2S:
        case IFEQ:
        case IFNE:
        case IFLT:
        case IFGE:
        case IFGT:
        case IFLE:
        case TABLESWITCH:
        case LOOKUPSWITCH:
        case IRETURN:
        case NEWARRAY:
        case ANEWARRAY:
            expected = BasicValue.INT_VALUE;
            break;
        case FNEG:
        case F2I:
        case F2L:
        case F2D:
        case FRETURN:
            expected = BasicValue.FLOAT_VALUE;
            break;
        case LNEG:
        case L2I:
        case L2F:
        case L2D:
        case LRETURN:
            expected = BasicValue.LONG_VALUE;
            break;
        case DNEG:
        case D2I:
        case D2F:
        case D2L:
        case DRETURN:
            expected = BasicValue.DOUBLE_VALUE;
            break;
        case GETFIELD:
            expected = newValue(Type
                    .getObjectType(((FieldInsnNode) insn).owner));
            break;
        case CHECKCAST:
            if (!value.isReference()) {
                throw new AnalyzerException(insn, null, "an object reference",
                        value);
            }
            return super.unaryOperation(insn, value);
        case ARRAYLENGTH:
            if (!isArrayValue(value)) {
                throw new AnalyzerException(insn, null, "an array reference",
                        value);
            }
            return super.unaryOperation(insn, value);
        case ARETURN:
        case ATHROW:
        case INSTANCEOF:
        case MONITORENTER:
        case MONITOREXIT:
        case IFNULL:
        case IFNONNULL:
            if (!value.isReference()) {
                throw new AnalyzerException(insn, null, "an object reference",
                        value);
            }
            return super.unaryOperation(insn, value);
        case PUTSTATIC:
            expected = newValue(Type.getType(((FieldInsnNode) insn).desc));
            break;
        default:
            throw new Error("Internal error.");
        }
        if (!isSubTypeOf(value, expected)) {
            throw new AnalyzerException(insn, null, expected, value);
        }
        return super.unaryOperation(insn, value);
    }

    @Override
    public BasicValue binaryOperation(final AbstractInsnNode insn,
            final BasicValue value1, final BasicValue value2)
            throws AnalyzerException {
        BasicValue expected1;
        BasicValue expected2;
        switch (insn.getOpcode()) {
        case IALOAD:
            expected1 = newValue(Type.getType("[I"));
            expected2 = BasicValue.INT_VALUE;
            break;
        case BALOAD:
            if (isSubTypeOf(value1, newValue(Type.getType("[Z")))) {
                expected1 = newValue(Type.getType("[Z"));
            } else {
                expected1 = newValue(Type.getType("[B"));
            }
            expected2 = BasicValue.INT_VALUE;
            break;
        case CALOAD:
            expected1 = newValue(Type.getType("[C"));
            expected2 = BasicValue.INT_VALUE;
            break;
        case SALOAD:
            expected1 = newValue(Type.getType("[S"));
            expected2 = BasicValue.INT_VALUE;
            break;
        case LALOAD:
            expected1 = newValue(Type.getType("[J"));
            expected2 = BasicValue.INT_VALUE;
            break;
        case FALOAD:
            expected1 = newValue(Type.getType("[F"));
            expected2 = BasicValue.INT_VALUE;
            break;
        case DALOAD:
            expected1 = newValue(Type.getType("[D"));
            expected2 = BasicValue.INT_VALUE;
            break;
        case AALOAD:
            expected1 = newValue(Type.getType("[Ljava/lang/Object;"));
            expected2 = BasicValue.INT_VALUE;
            break;
        case IADD:
        case ISUB:
        case IMUL:
        case IDIV:
        case IREM:
        case ISHL:
        case ISHR:
        case IUSHR:
        case IAND:
        case IOR:
        case IXOR:
        case IF_ICMPEQ:
        case IF_ICMPNE:
        case IF_ICMPLT:
        case IF_ICMPGE:
        case IF_ICMPGT:
        case IF_ICMPLE:
            expected1 = BasicValue.INT_VALUE;
            expected2 = BasicValue.INT_VALUE;
            break;
        case FADD:
        case FSUB:
        case FMUL:
        case FDIV:
        case FREM:
        case FCMPL:
        case FCMPG:
            expected1 = BasicValue.FLOAT_VALUE;
            expected2 = BasicValue.FLOAT_VALUE;
            break;
        case LADD:
        case LSUB:
        case LMUL:
        case LDIV:
        case LREM:
        case LAND:
        case LOR:
        case LXOR:
        case LCMP:
            expected1 = BasicValue.LONG_VALUE;
            expected2 = BasicValue.LONG_VALUE;
            break;
        case LSHL:
        case LSHR:
        case LUSHR:
            expected1 = BasicValue.LONG_VALUE;
            expected2 = BasicValue.INT_VALUE;
            break;
        case DADD:
        case DSUB:
        case DMUL:
        case DDIV:
        case DREM:
        case DCMPL:
        case DCMPG:
            expected1 = BasicValue.DOUBLE_VALUE;
            expected2 = BasicValue.DOUBLE_VALUE;
            break;
        case IF_ACMPEQ:
        case IF_ACMPNE:
            expected1 = BasicValue.REFERENCE_VALUE;
            expected2 = BasicValue.REFERENCE_VALUE;
            break;
        case PUTFIELD:
            FieldInsnNode fin = (FieldInsnNode) insn;
            expected1 = newValue(Type.getObjectType(fin.owner));
            expected2 = newValue(Type.getType(fin.desc));
            break;
        default:
            throw new Error("Internal error.");
        }
        if (!isSubTypeOf(value1, expected1)) {
            throw new AnalyzerException(insn, "First argument", expected1,
                    value1);
        } else if (!isSubTypeOf(value2, expected2)) {
            throw new AnalyzerException(insn, "Second argument", expected2,
                    value2);
        }
        if (insn.getOpcode() == AALOAD) {
            return getElementValue(value1);
        } else {
            return super.binaryOperation(insn, value1, value2);
        }
    }

    @Override
    public BasicValue ternaryOperation(final AbstractInsnNode insn,
            final BasicValue value1, final BasicValue value2,
            final BasicValue value3) throws AnalyzerException {
        BasicValue expected1;
        BasicValue expected3;
        switch (insn.getOpcode()) {
        case IASTORE:
            expected1 = newValue(Type.getType("[I"));
            expected3 = BasicValue.INT_VALUE;
            break;
        case BASTORE:
            if (isSubTypeOf(value1, newValue(Type.getType("[Z")))) {
                expected1 = newValue(Type.getType("[Z"));
            } else {
                expected1 = newValue(Type.getType("[B"));
            }
            expected3 = BasicValue.INT_VALUE;
            break;
        case CASTORE:
            expected1 = newValue(Type.getType("[C"));
            expected3 = BasicValue.INT_VALUE;
            break;
        case SASTORE:
            expected1 = newValue(Type.getType("[S"));
            expected3 = BasicValue.INT_VALUE;
            break;
        case LASTORE:
            expected1 = newValue(Type.getType("[J"));
            expected3 = BasicValue.LONG_VALUE;
            break;
        case FASTORE:
            expected1 = newValue(Type.getType("[F"));
            expected3 = BasicValue.FLOAT_VALUE;
            break;
        case DASTORE:
            expected1 = newValue(Type.getType("[D"));
            expected3 = BasicValue.DOUBLE_VALUE;
            break;
        case AASTORE:
            expected1 = value1;
            expected3 = BasicValue.REFERENCE_VALUE;
            break;
        default:
            throw new Error("Internal error.");
        }
        if (!isSubTypeOf(value1, expected1)) {
            throw new AnalyzerException(insn, "First argument", "a "
                    + expected1 + " array reference", value1);
        } else if (!BasicValue.INT_VALUE.equals(value2)) {
            throw new AnalyzerException(insn, "Second argument",
                    BasicValue.INT_VALUE, value2);
        } else if (!isSubTypeOf(value3, expected3)) {
            throw new AnalyzerException(insn, "Third argument", expected3,
                    value3);
        }
        return null;
    }

    @Override
    public BasicValue naryOperation(final AbstractInsnNode insn,
            final List<? extends BasicValue> values) throws AnalyzerException {
        int opcode = insn.getOpcode();
        if (opcode == MULTIANEWARRAY) {
            for (int i = 0; i < values.size(); ++i) {
                if (!BasicValue.INT_VALUE.equals(values.get(i))) {
                    throw new AnalyzerException(insn, null,
                            BasicValue.INT_VALUE, values.get(i));
                }
            }
        } else {
            int i = 0;
            int j = 0;
            if (opcode != INVOKESTATIC && opcode != INVOKEDYNAMIC) {
                Type owner = Type.getObjectType(((MethodInsnNode) insn).owner);
                if (!isSubTypeOf(values.get(i++), newValue(owner))) {
                    throw new AnalyzerException(insn, "Method owner",
                            newValue(owner), values.get(0));
                }
            }
            String desc = (opcode == INVOKEDYNAMIC) ? ((InvokeDynamicInsnNode) insn).desc
                    : ((MethodInsnNode) insn).desc;
            Type[] args = Type.getArgumentTypes(desc);
            while (i < values.size()) {
                BasicValue expected = newValue(args[j++]);
                BasicValue encountered = values.get(i++);
                if (!isSubTypeOf(encountered, expected)) {
                    throw new AnalyzerException(insn, "Argument " + j,
                            expected, encountered);
                }
            }
        }
        return super.naryOperation(insn, values);
    }

    @Override
    public void returnOperation(final AbstractInsnNode insn,
            final BasicValue value, final BasicValue expected)
            throws AnalyzerException {
        if (!isSubTypeOf(value, expected)) {
            throw new AnalyzerException(insn, "Incompatible return type",
                    expected, value);
        }
    }

    protected boolean isArrayValue(final BasicValue value) {
        return value.isReference();
    }

    protected BasicValue getElementValue(final BasicValue objectArrayValue)
            throws AnalyzerException {
        return BasicValue.REFERENCE_VALUE;
    }

    protected boolean isSubTypeOf(final BasicValue value,
            final BasicValue expected) {
        return value.equals(expected);
    }
}