io.joshworks.snappy.loader.InputArgumentsJavaAgentDetector Maven / Gradle / Ivy

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/*
 * Copyright 2012-2014 the original author or 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 io.joshworks.snappy.loader;

import java.io.File;
import java.io.IOException;
import java.lang.management.ManagementFactory;
import java.net.URL;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * A {@link JavaAgentDetector} that detects jars supplied via the {@code -javaagent} JVM
 * input argument.
 *
 * @author Andy Wilkinson
 * @since 1.1.0
 */
public class InputArgumentsJavaAgentDetector implements JavaAgentDetector {

    private static final String JAVA_AGENT_PREFIX = "-javaagent:";

    private final Set javaAgentJars;

    public InputArgumentsJavaAgentDetector() {
        this(getInputArguments());
    }

    InputArgumentsJavaAgentDetector(List inputArguments) {
        this.javaAgentJars = getJavaAgentJars(inputArguments);
    }

    private static List getInputArguments() {
        try {
            return AccessController.doPrivileged(new PrivilegedAction>() {
                @Override
                public List run() {
                    return ManagementFactory.getRuntimeMXBean().getInputArguments();
                }
            });
        } catch (Exception ex) {
            return Collections.emptyList();
        }
    }

    private Set getJavaAgentJars(List inputArguments) {
        Set javaAgentJars = new HashSet();
        for (String argument : inputArguments) {
            String path = getJavaAgentJarPath(argument);
            if (path != null) {
                try {
                    javaAgentJars.add(new File(path).getCanonicalFile().toURI().toURL());
                } catch (IOException ex) {
                    throw new IllegalStateException(
                            "Failed to determine canonical path of Java agent at path '"
                                    + path + "'");
                }
            }
        }
        return javaAgentJars;
    }

    private String getJavaAgentJarPath(String arg) {
        if (arg.startsWith(JAVA_AGENT_PREFIX)) {
            String path = arg.substring(JAVA_AGENT_PREFIX.length());
            int equalsIndex = path.indexOf('=');
            if (equalsIndex > -1) {
                path = path.substring(0, equalsIndex);
            }
            return path;
        }
        return null;
    }

    @Override
    public boolean isJavaAgentJar(URL url) {
        return this.javaAgentJars.contains(url);
    }

}