org.apache.openejb.javaagent.Agent Maven / Gradle / Ivy
The newest version!
/*
* 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.openejb.javaagent;
import java.io.Closeable;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.lang.instrument.Instrumentation;
import java.lang.management.ManagementFactory;
import java.lang.management.RuntimeMXBean;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.ReflectPermission;
import java.net.JarURLConnection;
import java.net.URL;
import java.net.URLConnection;
import java.security.Permission;
import java.security.ProtectionDomain;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;
public class Agent {
private static final Permission ACCESS_PERMISSION = new ReflectPermission("suppressAccessChecks");
private static String agentArgs;
private static Instrumentation instrumentation;
private static boolean initialized;
public static void premain(final String agentArgs, final Instrumentation instrumentation) {
if (Agent.instrumentation != null) {
return;
}
Agent.agentArgs = agentArgs;
Agent.instrumentation = instrumentation;
initialized = true;
instrumentation.addTransformer(new BootstrapTransformer());
}
public static void agentmain(final String agentArgs, final Instrumentation instrumentation) {
if (Agent.instrumentation != null) {
return;
}
Agent.agentArgs = agentArgs;
Agent.instrumentation = instrumentation;
initialized = true;
}
public static synchronized String getAgentArgs() {
final SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(ACCESS_PERMISSION);
}
checkInitialization();
return agentArgs;
}
/**
* Gets the instrumentation instance.
* You must have java.lang.ReflectPermission(suppressAccessChecks) to call this method
*
* @return the instrumentation instance
*/
public static synchronized Instrumentation getInstrumentation() {
final SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPermission(ACCESS_PERMISSION);
}
checkInitialization();
return instrumentation;
}
private static synchronized void checkInitialization() {
if (!initialized) {
try {
checkSystemClassPath();
dynamicLoadAgent();
} catch (final Exception e) {
new IllegalStateException("Unable to initialize agent", e).printStackTrace();
} finally {
initialized = true;
}
}
}
private static void checkSystemClassPath() throws NoSuchFieldException, IllegalAccessException {
if (instrumentation != null) {
return;
}
final Class systemAgentClass;
try {
final ClassLoader systemCl = ClassLoader.getSystemClassLoader();
systemAgentClass = systemCl.loadClass(Agent.class.getName());
} catch (final ClassNotFoundException e) {
// java-agent jar was not on the system class path
return;
}
final Field instrumentationField = systemAgentClass.getDeclaredField("instrumentation");
instrumentationField.setAccessible(true);
instrumentation = (Instrumentation) instrumentationField.get(null);
final Field agentArgsField = systemAgentClass.getDeclaredField("agentArgs");
agentArgsField.setAccessible(true);
agentArgs = (String) agentArgsField.get(null);
}
private static void dynamicLoadAgent() throws Exception {
if (instrumentation != null) {
return;
}
try {
final Class vmClass = Class.forName("com.sun.tools.attach.VirtualMachine");
final Method attachMethod = vmClass.getMethod("attach", String.class);
final Method loadAgentMethod = vmClass.getMethod("loadAgent", String.class);
// find the agentJar
final String agentPath = getAgentJar();
// get the pid of the current process (for attach command)
final String pid = getPid();
// attach to the vm
final Object vm = attachMethod.invoke(null, new String[]{pid});
// load our agent
loadAgentMethod.invoke(vm, agentPath);
// The AgentJar is loaded into the system classpath, and this class could
// be in a child classloader, so we need to double check the system classpath
checkSystemClassPath();
} catch (final ClassNotFoundException e) {
// not a Sun VM
} catch (final NoSuchMethodException e) {
// not a Sun VM
}
}
private static String getPid() {
// This relies on the undocumented convention of the
// RuntimeMXBean's name starting with the PID, but
// there appears to be no other way to obtain the
// current process' id, which we need for the attach
// process
final RuntimeMXBean bean = ManagementFactory.getRuntimeMXBean();
String pid = bean.getName();
if (pid.contains("@")) {
pid = pid.substring(0, pid.indexOf("@"));
}
return pid;
}
/**
* Try to find the openejb-javaagent jar, and if not found create a new jar
* file for the sole purpose of specifying an Agent-Class to load into the JVM.
*/
private static String getAgentJar() throws IOException {
final URL resource = Agent.class.getClassLoader().getResource(Agent.class.getName().replace('.', '/') + ".class");
if (resource == null) {
throw new IllegalStateException("Could not find Agent class file in class path");
}
final URLConnection urlConnection = resource.openConnection();
if (urlConnection instanceof JarURLConnection) {
final JarURLConnection jarURLConnection = (JarURLConnection) urlConnection;
return jarURLConnection.getJarFile().getName();
}
final InputStream in = urlConnection.getInputStream();
ZipOutputStream out = null;
File file = null;
try {
try {
file = File.createTempFile(Agent.class.getName(), ".jar");
} catch (final Throwable e) {
final File tmp = new File("tmp");
if (!tmp.exists() && !tmp.mkdirs()) {
throw new IOException("Failed to create local tmp directory: " + tmp.getAbsolutePath());
}
file = File.createTempFile(Agent.class.getName(), ".jar", tmp);
}
file.deleteOnExit();
out = new ZipOutputStream(new FileOutputStream(file));
// write manifest
out.putNextEntry(new ZipEntry("META-INF/MANIFEST.MF"));
try {
final PrintWriter writer = new PrintWriter(new OutputStreamWriter(out));
writer.println("Agent-Class: " + Agent.class.getName());
writer.println("Can-Redefine-Classes: true");
writer.println("Can-Retransform-Classes: true");
writer.flush();
} finally {
out.closeEntry();
}
// write agent class
out.putNextEntry(new ZipEntry(Agent.class.getName().replace('.', '/') + ".class"));
try {
final byte[] buffer = new byte[4096];
for (int count = in.read(buffer); count >= 0; count = in.read(buffer)) {
out.write(buffer, 0, count);
}
} finally {
out.closeEntry();
}
return file.getAbsolutePath();
} catch (final IOException e) {
if (file != null) {
if (!file.delete()) {
file.deleteOnExit();
}
}
throw e;
} finally {
close(in);
close(out);
}
}
private static void close(final Closeable closeable) {
if (closeable != null) {
try {
closeable.close();
} catch (final IOException ignored) {
// no-op
}
}
}
private static class BootstrapTransformer implements ClassFileTransformer {
private boolean done;
@Override
public byte[] transform(final ClassLoader loader, final String className, final Class classBeingRedefined, final ProtectionDomain protectionDomain, final byte[] classfileBuffer) throws IllegalClassFormatException {
try {
bootstrap(loader);
} catch (final Throwable e) {
done = true;
}
return classfileBuffer;
}
private void bootstrap(final ClassLoader loader) {
if (loader == null || done) {
return;
}
final String bootstrapClassName = "org.apache.openejb.persistence.PersistenceBootstrap";
final String bootstrapClassFile = "org/apache/openejb/persistence/PersistenceBootstrap.class";
if (loader.getResource(bootstrapClassFile) == null) {
return;
}
// We found the classloader that has the openejb-core jar
// we need to mark ourselves as "done" so that when we attempt to load
// the PersistenceBootstrap class it doesn't cause an infinite loop
done = true;
try {
final Class bootstrapClass = loader.loadClass(bootstrapClassName);
final Method bootstrap = bootstrapClass.getMethod("bootstrap", ClassLoader.class);
bootstrap.invoke(null, loader);
} catch (final Throwable e) {
Logger.getLogger(Agent.class.getName()).log(Level.WARNING, "Failed to invoke bootstrap: " + e.getMessage());
}
}
}
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy