/*
* Copyright 2014 - Present Rafael Winterhalter
*
* 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.
*/
import java.io.File;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.CodeSource;
import java.security.PrivilegedAction;
import java.security.ProtectionDomain;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
/**
* Copy from Byte Buddy
*/
public class Attacher {
/**
* Representation of the bootstrap {@link java.lang.ClassLoader}.
*/
private static final ClassLoader BOOTSTRAP_CLASS_LOADER = null;
/**
* The character that is used to mark the beginning of the argument to the agent.
*/
private static final String AGENT_ARGUMENT_SEPARATOR = "=";
/**
* The agent provides only {@code static} utility methods and should not be instantiated.
*/
private Attacher() {
throw new UnsupportedOperationException("This class is a utility class and not supposed to be instantiated");
}
/**
*
* Attaches the given agent Jar on the target process which must be a virtual machine process. The default attachment provider
* is used for applying the attachment. This operation blocks until the attachment is complete. If the current VM does not supply
* any known form of attachment to a remote VM, an {@link IllegalStateException} is thrown. The agent is not provided an argument.
*
*
* Important: It is only possible to attach to processes that are executed by the same operating system user.
*
*
* @param agentJar The agent jar file.
* @param processId The target process id.
*/
public static void attach(File agentJar, String processId) {
attach(agentJar, processId, null);
}
public static void attach(String processId) {
attach(trySelfResolve(), processId, null);
}
/**
*
* Attaches the given agent Jar on the target process which must be a virtual machine process. The default attachment provider
* is used for applying the attachment. This operation blocks until the attachment is complete. If the current VM does not supply
* any known form of attachment to a remote VM, an {@link IllegalStateException} is thrown.
*
*
* Important: It is only possible to attach to processes that are executed by the same operating system user.
*
*
* @param agentJar The agent jar file.
* @param processId The target process id.
* @param argument The argument to provide to the agent.
*/
public static void attach(File agentJar, String processId, String argument) {
install(processId, argument, new AgentProvider.ForExistingAgent(agentJar));
}
/**
* Installs a Java agent on a target VM.
*
* @param processId The process id of the target JVM process.
* @param argument The argument to provide to the agent.
* @param agentProvider The agent provider for the agent jar or library.
*/
private static void install(String processId, String argument, AgentProvider agentProvider) {
AttachmentProvider.Accessor attachmentAccessor = AttachmentProvider.DEFAULT.attempt();
if (!attachmentAccessor.isAvailable()) {
throw new IllegalStateException("No compatible attachment provider is available");
}
try {
Class virtualMachineType = attachmentAccessor.getVirtualMachineType();
String agent = agentProvider.resolve().getAbsolutePath();
Object virtualMachineInstance = virtualMachineType
.getMethod("attach", String.class)
.invoke(null, processId);
try {
virtualMachineType
.getMethod("loadAgent", String.class, String.class)
.invoke(virtualMachineInstance, agent, argument);
} finally {
virtualMachineType
.getMethod("detach")
.invoke(virtualMachineInstance);
}
} catch (RuntimeException exception) {
throw exception;
} catch (Exception exception) {
throw new IllegalStateException("Error during attachment using: " + AttachmentProvider.DEFAULT, exception);
}
}
/**
* Attempts to resolve the location of the {@link Attacher} class for a self-attachment. Doing so avoids the creation of a temporary jar file.
*
* @return The self-resolved jar file or {@code null} if the jar file cannot be located.
*/
private static File trySelfResolve() {
try {
ProtectionDomain protectionDomain = Attacher.class.getProtectionDomain();
if (protectionDomain == null) {
return null;
}
CodeSource codeSource = protectionDomain.getCodeSource();
if (codeSource == null) {
return null;
}
URL location = codeSource.getLocation();
if (!location.getProtocol().equals("file")) {
return null;
}
try {
File file = new File(location.toURI());
if (file.getPath().contains(AGENT_ARGUMENT_SEPARATOR)) {
return null;
}
return file;
} catch (URISyntaxException ignored) {
return new File(location.getPath());
}
} catch (Exception ignored) {
return null;
}
}
/**
* An attachment provider is responsible for making the Java attachment API available.
*/
public interface AttachmentProvider {
/**
* The default attachment provider to be used.
*/
AttachmentProvider DEFAULT = new Compound(ForModularizedVm.INSTANCE,
ForJ9Vm.INSTANCE,
ForStandardToolsJarVm.JVM_ROOT,
ForStandardToolsJarVm.JDK_ROOT,
ForStandardToolsJarVm.MACINTOSH,
ForUserDefinedToolsJar.INSTANCE,
ForEmulatedAttachment.INSTANCE);
/**
* Attempts the creation of an accessor for a specific JVM's attachment API.
*
* @return The accessor this attachment provider can supply for the currently running JVM.
*/
Accessor attempt();
/**
* An accessor for a JVM's attachment API.
*/
interface Accessor {
/**
* The name of the {@code VirtualMachine} class on any OpenJDK or Oracle JDK implementation.
*/
String VIRTUAL_MACHINE_TYPE_NAME = "com.sun.tools.attach.VirtualMachine";
/**
* The name of the {@code VirtualMachine} class on IBM J9 VMs.
*/
String VIRTUAL_MACHINE_TYPE_NAME_J9 = "com.ibm.tools.attach.VirtualMachine";
/**
* Determines if this accessor is applicable for the currently running JVM.
*
* @return {@code true} if this accessor is available.
*/
boolean isAvailable();
/**
* Returns {@code true} if this accessor prohibits attachment to the same virtual machine in Java 9 and later.
*
* @return {@code true} if this accessor prohibits attachment to the same virtual machine in Java 9 and later.
*/
boolean isExternalAttachmentRequired();
/**
* Returns a {@code VirtualMachine} class. This method must only be called for available accessors.
*
* @return The virtual machine type.
*/
Class getVirtualMachineType();
/**
* Returns a description of a virtual machine class for an external attachment.
*
* @return A description of the external attachment.
*/
ExternalAttachment getExternalAttachment();
/**
* A canonical implementation of an unavailable accessor.
*/
enum Unavailable implements Accessor {
/**
* The singleton instance.
*/
INSTANCE;
/**
* {@inheritDoc}
*/
public boolean isAvailable() {
return false;
}
/**
* {@inheritDoc}
*/
public boolean isExternalAttachmentRequired() {
throw new IllegalStateException("Cannot read the virtual machine type for an unavailable accessor");
}
/**
* {@inheritDoc}
*/
public Class getVirtualMachineType() {
throw new IllegalStateException("Cannot read the virtual machine type for an unavailable accessor");
}
/**
* {@inheritDoc}
*/
public ExternalAttachment getExternalAttachment() {
throw new IllegalStateException("Cannot read the virtual machine type for an unavailable accessor");
}
}
/**
* Describes an external attachment to a Java virtual machine.
*/
class ExternalAttachment {
/**
* The fully-qualified binary name of the virtual machine type.
*/
private final String virtualMachineType;
/**
* The class path elements required for loading the supplied virtual machine type.
*/
private final List classPath;
/**
* Creates an external attachment.
*
* @param virtualMachineType The fully-qualified binary name of the virtual machine type.
* @param classPath The class path elements required for loading the supplied virtual machine type.
*/
public ExternalAttachment(String virtualMachineType, List classPath) {
this.virtualMachineType = virtualMachineType;
this.classPath = classPath;
}
/**
* Returns the fully-qualified binary name of the virtual machine type.
*
* @return The fully-qualified binary name of the virtual machine type.
*/
public String getVirtualMachineType() {
return virtualMachineType;
}
/**
* Returns the class path elements required for loading the supplied virtual machine type.
*
* @return The class path elements required for loading the supplied virtual machine type.
*/
public List getClassPath() {
return classPath;
}
}
/**
* A simple implementation of an accessible accessor.
*/
abstract class Simple implements Accessor {
/**
* A {@code VirtualMachine} class.
*/
protected final Class virtualMachineType;
/**
* Creates a new simple accessor.
*
* @param virtualMachineType A {@code VirtualMachine} class.
*/
protected Simple(Class virtualMachineType) {
this.virtualMachineType = virtualMachineType;
}
/**
*
* Creates an accessor by reading the process id from the JMX runtime bean and by attempting
* to load the {@code com.sun.tools.attach.VirtualMachine} class from the provided class loader.
*
*
* This accessor is supposed to work on any implementation of the OpenJDK or Oracle JDK.
*
*
* @param classLoader A class loader that is capable of loading the virtual machine type.
* @param classPath The class path required to load the virtual machine class.
* @return An appropriate accessor.
*/
public static Accessor of(ClassLoader classLoader, File... classPath) {
try {
return new Simple.WithExternalAttachment(Class.forName(VIRTUAL_MACHINE_TYPE_NAME,
false,
classLoader), Arrays.asList(classPath));
} catch (ClassNotFoundException ignored) {
return Unavailable.INSTANCE;
}
}
/**
*
* Creates an accessor by reading the process id from the JMX runtime bean and by attempting
* to load the {@code com.ibm.tools.attach.VirtualMachine} class from the provided class loader.
*
*
* This accessor is supposed to work on any implementation of IBM's J9.
*
*
* @return An appropriate accessor.
*/
public static Accessor ofJ9() {
try {
return new Simple.WithExternalAttachment(ClassLoader.getSystemClassLoader().loadClass(VIRTUAL_MACHINE_TYPE_NAME_J9),
Collections.emptyList());
} catch (ClassNotFoundException ignored) {
return Unavailable.INSTANCE;
}
}
/**
* {@inheritDoc}
*/
public boolean isAvailable() {
return true;
}
/**
* {@inheritDoc}
*/
public Class getVirtualMachineType() {
return virtualMachineType;
}
/**
* A simple implementation of an accessible accessor that allows for external attachment.
*/
protected static class WithExternalAttachment extends Simple {
/**
* The class path required for loading the virtual machine type.
*/
private final List classPath;
/**
* Creates a new simple accessor that allows for external attachment.
*
* @param virtualMachineType The {@code com.sun.tools.attach.VirtualMachine} class.
* @param classPath The class path required for loading the virtual machine type.
*/
public WithExternalAttachment(Class virtualMachineType, List classPath) {
super(virtualMachineType);
this.classPath = classPath;
}
/**
* {@inheritDoc}
*/
public boolean isExternalAttachmentRequired() {
return true;
}
/**
* {@inheritDoc}
*/
public ExternalAttachment getExternalAttachment() {
return new ExternalAttachment(virtualMachineType.getName(), classPath);
}
}
/**
* A simple implementation of an accessible accessor that attaches using a virtual machine emulation that does not require external attachment.
*/
protected static class WithDirectAttachment extends Simple {
/**
* Creates a new simple accessor that implements direct attachment.
*
* @param virtualMachineType A {@code VirtualMachine} class.
*/
public WithDirectAttachment(Class virtualMachineType) {
super(virtualMachineType);
}
/**
* {@inheritDoc}
*/
public boolean isExternalAttachmentRequired() {
return false;
}
/**
* {@inheritDoc}
*/
public ExternalAttachment getExternalAttachment() {
throw new IllegalStateException("Cannot apply external attachment");
}
}
}
}
/**
* An attachment provider that locates the attach API directly from the system class loader, as possible since
* introducing the Java module system via the {@code jdk.attach} module.
*/
enum ForModularizedVm implements AttachmentProvider {
/**
* The singleton instance.
*/
INSTANCE;
/**
* {@inheritDoc}
*/
public Accessor attempt() {
return Accessor.Simple.of(ClassLoader.getSystemClassLoader());
}
}
/**
* An attachment provider that locates the attach API directly from the system class loader expecting
* an IBM J9 VM.
*/
enum ForJ9Vm implements AttachmentProvider {
/**
* The singleton instance.
*/
INSTANCE;
/**
* {@inheritDoc}
*/
public Accessor attempt() {
return Accessor.Simple.ofJ9();
}
}
/**
* An attachment provider that is dependant on the existence of a tools.jar file on the local
* file system.
*/
enum ForStandardToolsJarVm implements AttachmentProvider {
/**
* An attachment provider that locates the tools.jar from a Java home directory.
*/
JVM_ROOT("../lib/tools.jar"),
/**
* An attachment provider that locates the tools.jar from a Java installation directory.
* In practice, several virtual machines do not return the JRE's location for the
* java.home property against the property's specification.
*/
JDK_ROOT("lib/tools.jar"),
/**
* An attachment provider that locates the tools.jar as it is set for several JVM
* installations on Apple Macintosh computers.
*/
MACINTOSH("../Classes/classes.jar");
/**
* The Java home system property.
*/
private static final String JAVA_HOME_PROPERTY = "java.home";
/**
* The path to the tools.jar file, starting from the Java home directory.
*/
private final String toolsJarPath;
/**
* Creates a new attachment provider that loads the virtual machine class from the tools.jar.
*
* @param toolsJarPath The path to the tools.jar file, starting from the Java home directory.
*/
ForStandardToolsJarVm(String toolsJarPath) {
this.toolsJarPath = toolsJarPath;
}
/**
* {@inheritDoc}
*/
public Accessor attempt() {
File toolsJar = new File(System.getProperty(JAVA_HOME_PROPERTY), toolsJarPath);
try {
return toolsJar.isFile() && toolsJar.canRead()
? Accessor.Simple.of(new URLClassLoader(new URL[]{toolsJar.toURI().toURL()}, BOOTSTRAP_CLASS_LOADER), toolsJar)
: Accessor.Unavailable.INSTANCE;
} catch (MalformedURLException exception) {
throw new IllegalStateException("Could not represent " + toolsJar + " as URL");
}
}
}
/**
* An attachment provider that attempts to locate a {@code tools.jar} from a custom location set via a system property.
*/
enum ForUserDefinedToolsJar implements AttachmentProvider {
/**
* The singelton instance.
*/
INSTANCE;
/**
* The property being read for locating {@code tools.jar}.
*/
public static final String PROPERTY = "net.bytebuddy.agent.toolsjar";
/**
* {@inheritDoc}
*/
public Accessor attempt() {
String location = System.getProperty(PROPERTY);
if (location == null) {
return Accessor.Unavailable.INSTANCE;
} else {
File toolsJar = new File(location);
try {
return Accessor.Simple.of(new URLClassLoader(new URL[]{toolsJar.toURI().toURL()}, BOOTSTRAP_CLASS_LOADER), toolsJar);
} catch (MalformedURLException exception) {
throw new IllegalStateException("Could not represent " + toolsJar + " as URL");
}
}
}
}
/**
* An attachment provider that uses Byte Buddy's attachment API emulation. To use this feature, JNA is required.
*/
enum ForEmulatedAttachment implements AttachmentProvider {
/**
* The singleton instance.
*/
INSTANCE;
/**
* {@inheritDoc}
*/
public Accessor attempt() {
try {
return new Accessor.Simple.WithDirectAttachment(VirtualMachine.Resolver.INSTANCE.get());
} catch (Throwable ignored) {
return Accessor.Unavailable.INSTANCE;
}
}
}
/**
* A compound attachment provider that attempts the attachment by delegation to other providers. If
* none of the providers of this compound provider is capable of providing a valid accessor, an
* non-available accessor is returned.
*/
class Compound implements AttachmentProvider {
/**
* A list of attachment providers in the order of their application.
*/
private final List attachmentProviders;
/**
* Creates a new compound attachment provider.
*
* @param attachmentProvider A list of attachment providers in the order of their application.
*/
public Compound(AttachmentProvider... attachmentProvider) {
this(Arrays.asList(attachmentProvider));
}
/**
* Creates a new compound attachment provider.
*
* @param attachmentProviders A list of attachment providers in the order of their application.
*/
public Compound(List attachmentProviders) {
this.attachmentProviders = new ArrayList();
for (AttachmentProvider attachmentProvider : attachmentProviders) {
if (attachmentProvider instanceof Compound) {
this.attachmentProviders.addAll(((Compound) attachmentProvider).attachmentProviders);
} else {
this.attachmentProviders.add(attachmentProvider);
}
}
}
/**
* {@inheritDoc}
*/
public Accessor attempt() {
for (AttachmentProvider attachmentProvider : attachmentProviders) {
Accessor accessor = attachmentProvider.attempt();
if (accessor.isAvailable()) {
return accessor;
}
}
return Accessor.Unavailable.INSTANCE;
}
}
}
/**
* A process provider is responsible for providing the process id of the current VM.
*/
public interface ProcessProvider {
/**
* Resolves a process id for the current JVM.
*
* @return The resolved process id.
*/
String resolve();
/**
* Supplies the current VM's process id.
*/
enum ForCurrentVm implements ProcessProvider {
/**
* The singleton instance.
*/
INSTANCE;
/**
* The best process provider for the current VM.
*/
private final ProcessProvider dispatcher;
/**
* Creates a process provider that supplies the current VM's process id.
*/
ForCurrentVm() {
dispatcher = ForJava9CapableVm.make();
}
/**
* {@inheritDoc}
*/
public String resolve() {
return dispatcher.resolve();
}
/**
* A process provider for a legacy VM that reads the process id from its JMX properties. This strategy
* is only used prior to Java 9 such that the java.management module never is resolved, even if
* the module system is used, as the module system was not available in any relevant JVM version.
*/
protected enum ForLegacyVm implements ProcessProvider {
/**
* The singleton instance.
*/
INSTANCE;
/**
* {@inheritDoc}
*/
public String resolve() {
String runtimeName;
try {
Method method = Class.forName("java.lang.management.ManagementFactory").getMethod("getRuntimeMXBean");
runtimeName = (String) method.getReturnType().getMethod("getName").invoke(method.invoke(null));
} catch (Exception exception) {
throw new IllegalStateException("Failed to access VM name via management factory", exception);
}
int processIdIndex = runtimeName.indexOf('@');
if (processIdIndex == -1) {
throw new IllegalStateException("Cannot extract process id from runtime management bean");
} else {
return runtimeName.substring(0, processIdIndex);
}
}
}
/**
* A process provider for a Java 9 capable VM with access to the introduced process API.
*/
protected static class ForJava9CapableVm implements ProcessProvider {
/**
* The {@code java.lang.ProcessHandle#current()} method.
*/
private final Method current;
/**
* The {@code java.lang.ProcessHandle#pid()} method.
*/
private final Method pid;
/**
* Creates a new Java 9 capable dispatcher for reading the current process's id.
*
* @param current The {@code java.lang.ProcessHandle#current()} method.
* @param pid The {@code java.lang.ProcessHandle#pid()} method.
*/
protected ForJava9CapableVm(Method current, Method pid) {
this.current = current;
this.pid = pid;
}
/**
* Attempts to create a dispatcher for a Java 9 VM and falls back to a legacy dispatcher
* if this is not possible.
*
* @return A dispatcher for the current VM.
*/
public static ProcessProvider make() {
try {
return new ForJava9CapableVm(Class.forName("java.lang.ProcessHandle").getMethod("current"),
Class.forName("java.lang.ProcessHandle").getMethod("pid"));
} catch (Exception ignored) {
return ForLegacyVm.INSTANCE;
}
}
/**
* {@inheritDoc}
*/
public String resolve() {
try {
return pid.invoke(current.invoke(null)).toString();
} catch (IllegalAccessException exception) {
throw new IllegalStateException("Cannot access Java 9 process API", exception);
} catch (InvocationTargetException exception) {
throw new IllegalStateException("Error when accessing Java 9 process API", exception.getTargetException());
}
}
}
}
}
/**
* An agent provider is responsible for handling and providing the jar file of an agent that is being attached.
*/
protected interface AgentProvider {
/**
* Provides an agent jar file for attachment.
*
* @return The provided agent.
* @throws IOException If the agent cannot be written to disk.
*/
File resolve() throws IOException;
/**
* An agent provider that supplies an existing agent that is not deleted after attachment.
*/
class ForExistingAgent implements AgentProvider {
/**
* The supplied agent.
*/
private final File agent;
/**
* Creates an agent provider for an existing agent.
*
* @param agent The supplied agent.
*/
protected ForExistingAgent(File agent) {
this.agent = agent;
}
/**
* {@inheritDoc}
*/
public File resolve() {
return agent;
}
}
}
/**
* An attachment evaluator is responsible for deciding if an agent can be attached from the current process.
*/
protected interface AttachmentTypeEvaluator {
/**
* Checks if the current VM requires external attachment for the supplied process id.
*
* @param processId The process id of the process to which to attach.
* @return {@code true} if the current VM requires external attachment for the supplied process.
*/
boolean requiresExternalAttachment(String processId);
/**
* An installation action for creating an attachment type evaluator.
*/
enum InstallationAction implements PrivilegedAction {
/**
* The singleton instance.
*/
INSTANCE;
/**
* The OpenJDK's property for specifying the legality of self-attachment.
*/
private static final String JDK_ALLOW_SELF_ATTACH = "jdk.attach.allowAttachSelf";
/**
* {@inheritDoc}
*/
public AttachmentTypeEvaluator run() {
try {
if (Boolean.getBoolean(JDK_ALLOW_SELF_ATTACH)) {
return Disabled.INSTANCE;
} else {
return new ForJava9CapableVm(Class.forName("java.lang.ProcessHandle").getMethod("current"),
Class.forName("java.lang.ProcessHandle").getMethod("pid"));
}
} catch (Exception ignored) {
return Disabled.INSTANCE;
}
}
}
/**
* An attachment type evaluator that never requires external attachment.
*/
enum Disabled implements AttachmentTypeEvaluator {
/**
* The singleton instance.
*/
INSTANCE;
/**
* {@inheritDoc}
*/
public boolean requiresExternalAttachment(String processId) {
return false;
}
}
/**
* An attachment type evaluator that checks a process id against the current process id.
*/
class ForJava9CapableVm implements AttachmentTypeEvaluator {
/**
* The {@code java.lang.ProcessHandle#current()} method.
*/
private final Method current;
/**
* The {@code java.lang.ProcessHandle#pid()} method.
*/
private final Method pid;
/**
* Creates a new attachment type evaluator.
*
* @param current The {@code java.lang.ProcessHandle#current()} method.
* @param pid The {@code java.lang.ProcessHandle#pid()} method.
*/
protected ForJava9CapableVm(Method current, Method pid) {
this.current = current;
this.pid = pid;
}
/**
* {@inheritDoc}
*/
public boolean requiresExternalAttachment(String processId) {
try {
return pid.invoke(current.invoke(null)).toString().equals(processId);
} catch (IllegalAccessException exception) {
throw new IllegalStateException("Cannot access Java 9 process API", exception);
} catch (InvocationTargetException exception) {
throw new IllegalStateException("Error when accessing Java 9 process API", exception.getTargetException());
}
}
}
}
}