org.moditect.internal.analyzer.ServiceLoaderUseScanner.java Source code

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Here is the source code for org.moditect.internal.analyzer.ServiceLoaderUseScanner.java

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/**
 *  Copyright 2017 - 2018 The ModiTect authors
 *
 *  Licensed 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.moditect.internal.analyzer;

import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Path;
import java.util.HashSet;
import java.util.Set;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;

import org.moditect.spi.log.Log;
import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.MethodVisitor;
import org.objectweb.asm.Opcodes;
import org.objectweb.asm.Type;

public class ServiceLoaderUseScanner {

    private final Log log;

    public ServiceLoaderUseScanner(Log log) {
        this.log = log;
    }

    public Set<String> getUsedServices(Path jar) {
        Set<String> usedServices = new HashSet<>();

        try (JarFile jarFile = new JarFile(jar.toFile())) {
            jarFile.stream().filter(je -> !je.isDirectory() && je.getName().endsWith(".class"))
                    .forEach(je -> usedServices.addAll(getUsedServices(jarFile, je)));
        } catch (IOException e) {
            throw new RuntimeException("Couldn't open or close JAR file " + jar, e);
        }

        return usedServices;
    }

    private Set<String> getUsedServices(JarFile jarFile, JarEntry je) {
        Set<String> usedServices = new HashSet<>();

        try (InputStream classFile = jarFile.getInputStream(je)) {
            new ClassReader(classFile).accept(new ClassVisitor(Opcodes.ASM6) {

                @Override
                public MethodVisitor visitMethod(int access, String name, String desc, String signature,
                        String[] exceptions) {

                    return new MethodVisitor(Opcodes.ASM6) {

                        private Type lastType;

                        @Override
                        public void visitMethodInsn(int opcode, String owner, String name, String desc,
                                boolean itf) {
                            if (owner.equals("java/util/ServiceLoader") && name.equals("load")) {
                                if (lastType == null) {
                                    // TODO Log class/method
                                    log.warn(
                                            "Cannot derive uses clause from service loader invocation with non constant class literal");
                                } else {
                                    usedServices.add(lastType.getClassName());
                                }
                            }
                        }

                        @Override
                        public void visitLdcInsn(Object cst) {
                            if (cst instanceof Type) {
                                lastType = (Type) cst;
                            }
                        };
                    };
                }
            }, 0);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }

        return usedServices;
    }

}