org.apache.drill.exec.compile.AsmUtil.java Source code

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Here is the source code for org.apache.drill.exec.compile.AsmUtil.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.drill.exec.compile;

import java.io.PrintWriter;
import java.io.StringWriter;

import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.tree.ClassNode;
import org.objectweb.asm.util.TraceClassVisitor;
import org.slf4j.Logger;

/**
 * Utilities commonly used with ASM.
 *
 * <p>There are several class verification utilities which use
 * CheckClassAdapter (DrillCheckClassAdapter) to ensure classes are well-formed;
 * these are packaged as boolean functions so that they can be used in assertions.
 */
public class AsmUtil {
    // This class only contains static utilities.
    private AsmUtil() {
    }

    /**
     * Check to see if a class is well-formed.
     *
     * @param logger the logger to write to if a problem is found
     * @param logTag a tag to print to the log if a problem is found
     * @param classNode the class to check
     * @return true if the class is ok, false otherwise
     */
    public static boolean isClassOk(final Logger logger, final String logTag, final ClassNode classNode) {
        final StringWriter sw = new StringWriter();
        final ClassWriter verifyWriter = new ClassWriter(ClassWriter.COMPUTE_FRAMES);
        classNode.accept(verifyWriter);
        final ClassReader ver = new ClassReader(verifyWriter.toByteArray());
        try {
            DrillCheckClassAdapter.verify(ver, false, new PrintWriter(sw));
        } catch (final Exception e) {
            logger.info("Caught exception verifying class:");
            logClass(logger, logTag, classNode);
            throw e;
        }
        final String output = sw.toString();
        if (!output.isEmpty()) {
            logger.info("Invalid class:\n" + output);
            return false;
        }

        return true;
    }

    /**
     * Check to see if a class is well-formed.
     *
     * @param logger the logger to write to if a problem is found
     * @param logTag a tag to print to the log if a problem is found
     * @param classBytes the bytecode of the class to check
     * @return true if the class is ok, false otherwise
     */
    public static boolean isClassBytesOk(final Logger logger, final String logTag, final byte[] classBytes) {
        final ClassNode classNode = classFromBytes(classBytes, 0);
        return isClassOk(logger, logTag, classNode);
    }

    /**
     * Create a ClassNode from bytecode.
     *
     * @param classBytes the bytecode
     * @param asmReaderFlags flags for ASM; see {@link org.objectweb.asm.ClassReader#accept(org.objectweb.asm.ClassVisitor, int)}
     * @return the ClassNode
     */
    public static ClassNode classFromBytes(final byte[] classBytes, final int asmReaderFlags) {
        final ClassNode classNode = new ClassNode(CompilationConfig.ASM_API_VERSION);
        final ClassReader classReader = new ClassReader(classBytes);
        classReader.accept(classNode, asmReaderFlags);
        return classNode;
    }

    /**
     * Write a class to the log.
     *
     * <p>
     * Writes at level TRACE.
     *
     * @param logger
     *          the logger to write to
     * @param logTag
     *          a tag to print to the log
     * @param classNode
     *          the class
     */
    public static void logClass(final Logger logger, final String logTag, final ClassNode classNode) {
        if (logger.isTraceEnabled()) {
            logger.trace(logTag);
            final StringWriter stringWriter = new StringWriter();
            final PrintWriter printWriter = new PrintWriter(stringWriter);
            final TraceClassVisitor traceClassVisitor = new TraceClassVisitor(printWriter);
            classNode.accept(traceClassVisitor);
            logger.trace(stringWriter.toString());
        }
    }

    /**
     * Write a class to the log.
     *
     * <p>Writes at level DEBUG.
     *
     * @param logTag a tag to print to the log
     * @param classBytes the class' bytecode
     * @param logger the logger to write to
     */
    public static void logClassFromBytes(final Logger logger, final String logTag, final byte[] classBytes) {
        final ClassNode classNode = classFromBytes(classBytes, 0);
        logClass(logger, logTag, classNode);
    }

    /**
     * Determine if the given opcode is a load of a constant (xCONST_y).
     *
     * @param opcode the opcode
     * @return true if the opcode is one of the constant loading ones, false otherwise
     */
    public static boolean isXconst(final int opcode) {
        switch (opcode) {
        case Opcodes.ICONST_0:
        case Opcodes.ICONST_1:
        case Opcodes.ICONST_2:
        case Opcodes.ICONST_3:
        case Opcodes.ICONST_4:
        case Opcodes.ICONST_5:
        case Opcodes.ICONST_M1:
        case Opcodes.DCONST_0:
        case Opcodes.DCONST_1:
        case Opcodes.FCONST_0:
        case Opcodes.FCONST_1:
        case Opcodes.LCONST_0:
        case Opcodes.LCONST_1:
            return true;
        }

        return false;
    }

    /**
     * Determine if the given opcode is an ADD of some kind (xADD).
     *
     * @param opcode the opcode
     * @return true if the opcode is one of the ADDs, false otherwise
     */
    public static boolean isXadd(final int opcode) {
        switch (opcode) {
        case Opcodes.IADD:
        case Opcodes.DADD:
        case Opcodes.FADD:
        case Opcodes.LADD:
            return true;
        }

        return false;
    }
}