package net.bytebuddy.agent;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import lombok.EqualsAndHashCode;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.instrument.Instrumentation;
import java.lang.management.ManagementFactory;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.*;
import java.util.jar.Attributes;
import java.util.jar.JarEntry;
import java.util.jar.JarOutputStream;
import java.util.jar.Manifest;
import java.util.logging.Logger;
/**
* <p>
* The Byte Buddy agent provides a JVM {@link java.lang.instrument.Instrumentation} in order to allow Byte Buddy the
* redefinition of already loaded classes. An agent must normally be specified via the command line via the
* {@code javaagent} parameter. As an argument to this parameter, one must specify the location of this agent's jar
* file such as for example in
* </p>
* <p>
* <code>
* java -javaagent:byte-buddy-agent.jar -jar app.jar
* </code>
* </p>
* <p>
* <b>Note</b>: The runtime installation of a Java agent is not possible on all JVMs. See the documentation for
* {@link ByteBuddyAgent#install()} for details on JVMs that are supported out of the box.
* </p>
* <p>
* <b>Important</b>: This class's name is known to the Byte Buddy main application and must not be altered.
* </p>
* <p>
* <b>Note</b>: Byte Buddy does not execute code using an {@link java.security.AccessController}. If a security manager
* is present, the user of this class is responsible for assuring any required privileges.
* </p>
*/
public class ByteBuddyAgent {
/**
* The manifest property specifying the agent class.
*/
private static final String AGENT_CLASS_PROPERTY = "Agent-Class";
/**
* The manifest property specifying the <i>can redefine</i> property.
*/
private static final String CAN_REDEFINE_CLASSES_PROPERTY = "Can-Redefine-Classes";
/**
* The manifest property specifying the <i>can retransform</i> property.
*/
private static final String CAN_RETRANSFORM_CLASSES_PROPERTY = "Can-Retransform-Classes";
/**
* The manifest property specifying the <i>can set native method prefix</i> property.
*/
private static final String CAN_SET_NATIVE_METHOD_PREFIX = "Can-Set-Native-Method-Prefix";
/**
* The manifest property value for the manifest version.
*/
private static final String MANIFEST_VERSION_VALUE = "1.0";
/**
* The size of the buffer for copying the agent installer file into another jar.
*/
private static final int BUFFER_SIZE = 1024;
/**
* Convenience indices for reading and writing to the buffer to make the code more readable.
*/
private static final int START_INDEX = 0, END_OF_FILE = -1;
/**
* The status code expected as a result of a successful attachment.
*/
private static final int SUCCESSFUL_ATTACH = 0;
/**
* Base for access to a reflective member to make the code more readable.
*/
private static final Object STATIC_MEMBER = null;
/**
* Representation of the bootstrap {@link java.lang.ClassLoader}.
*/
private static final ClassLoader BOOTSTRAP_CLASS_LOADER = null;
/**
* Represents a no-op argument for a dynamic agent attachment.
*/
private static final String WITHOUT_ARGUMENT = null;
/**
* The naming prefix of all artifacts for an attacher jar.
*/
private static final String ATTACHER_FILE_NAME = "byteBuddyAttacher";
/**
* The file extension for a class file.
*/
private static final String CLASS_FILE_EXTENSION = ".class";
/**
* The file extension for a jar file.
*/
private static final String JAR_FILE_EXTENSION = ".jar";
/**
* The class path argument to specify the class path elements.
*/
private static final String CLASS_PATH_ARGUMENT = "-cp";
/**
* The Java property denoting the Java home directory.
*/
private static final String JAVA_HOME = "java.home";
/**
* The Java property denoting the operating system name.
*/
private static final String OS_NAME = "os.name";
/**
* The name of the method for reading the installer's instrumentation.
*/
private static final String INSTRUMENTATION_METHOD = "getInstrumentation";
/**
* An indicator variable to express that no instrumentation is available.
*/
private static final Instrumentation UNAVAILABLE = null;
/**
* The attachment type evaluator to be used for determining if an attachment requires an external process.
*/
private static final AttachmentTypeEvaluator ATTACHMENT_TYPE_EVALUATOR = AccessController.doPrivileged(AttachmentTypeEvaluator.InstallationAction.INSTANCE);
/**
* The agent provides only {@code static} utility methods and should not be instantiated.
*/
private ByteBuddyAgent() {
throw new UnsupportedOperationException();
}
/**
* <p>
* Looks up the {@link java.lang.instrument.Instrumentation} instance of an installed Byte Buddy agent. Note that
* this method implies reflective lookup and reflective invocation such that the returned value should be cached
* rather than calling this method several times.
* </p>
* <p>
* <b>Note</b>: This method throws an {@link java.lang.IllegalStateException} If the Byte Buddy agent is not
* properly installed.
* </p>
*
* @return The {@link java.lang.instrument.Instrumentation} instance which is provided by an installed
* Byte Buddy agent.
*/
public static Instrumentation getInstrumentation() {
Instrumentation instrumentation = doGetInstrumentation();
if (instrumentation == null) {
throw new IllegalStateException("The Byte Buddy agent is not initialized");
}
return instrumentation;
}
/**
* 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.
*
* @param agentJar The agent jar file.
* @param processId The target process id.
*/
public static void attach(File agentJar, String processId) {
attach(agentJar, processId, WITHOUT_ARGUMENT);
}
/**
* 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.
*
* @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) {
attach(agentJar, processId, argument, AttachmentProvider.DEFAULT);
}
/**
* Attaches the given agent Jar on the target process which must be a virtual machine process. This operation blocks until the
* attachment is complete. The agent is not provided an argument.
*
* @param agentJar The agent jar file.
* @param processId The target process id.
* @param attachmentProvider The attachment provider to use.
*/
public static void attach(File agentJar, String processId, AttachmentProvider attachmentProvider) {
attach(agentJar, processId, WITHOUT_ARGUMENT, attachmentProvider);
}
/**
* Attaches the given agent Jar on the target process which must be a virtual machine process. This operation blocks until the
* attachment is complete.
*
* @param agentJar The agent jar file.
* @param processId The target process id.
* @param argument The argument to provide to the agent.
* @param attachmentProvider The attachment provider to use.
*/
public static void attach(File agentJar, String processId, String argument, AttachmentProvider attachmentProvider) {
install(attachmentProvider, processId, argument, new AgentProvider.ForExistingAgent(agentJar));
}
/**
* 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.
*
* @param agentJar The agent jar file.
* @param processProvider A provider of the target process id.
*/
public static void attach(File agentJar, ProcessProvider processProvider) {
attach(agentJar, processProvider, WITHOUT_ARGUMENT);
}
/**
* 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.
*
* @param agentJar The agent jar file.
* @param processProvider A provider of the target process id.
* @param argument The argument to provide to the agent.
*/
public static void attach(File agentJar, ProcessProvider processProvider, String argument) {
attach(agentJar, processProvider, argument, AttachmentProvider.DEFAULT);
}
/**
* Attaches the given agent Jar on the target process which must be a virtual machine process. This operation blocks until the
* attachment is complete. The agent is not provided an argument.
*
* @param agentJar The agent jar file.
* @param processProvider A provider of the target process id.
* @param attachmentProvider The attachment provider to use.
*/
public static void attach(File agentJar, ProcessProvider processProvider, AttachmentProvider attachmentProvider) {
attach(agentJar, processProvider, WITHOUT_ARGUMENT, attachmentProvider);
}
/**
* Attaches the given agent Jar on the target process which must be a virtual machine process. This operation blocks until the
* attachment is complete.
*
* @param agentJar The agent jar file.
* @param processProvider A provider of the target process id.
* @param argument The argument to provide to the agent.
* @param attachmentProvider The attachment provider to use.
*/
public static void attach(File agentJar, ProcessProvider processProvider, String argument, AttachmentProvider attachmentProvider) {
install(attachmentProvider, processProvider.resolve(), argument, new AgentProvider.ForExistingAgent(agentJar));
}
/**
* <p>
* Installs an agent on the currently running Java virtual machine. Unfortunately, this does
* not always work. The runtime installation of a Java agent is supported for:
* </p>
* <ul>
* <li><b>JVM version 9+</b>: For Java VM of at least version 9, the attachment API was merged
* into a Jigsaw module and the runtime installation is always possible.</li>
* <li><b>OpenJDK / Oracle JDK / IBM J9 versions 8-</b>: The installation for HotSpot is only
* possible when bundled with a JDK up until Java version 8. It is not possible for runtime-only
* installations of HotSpot or J9 for these versions.</li>
* </ul>
* <p>
* If an agent cannot be installed, an {@link IllegalStateException} is thrown.
* </p>
* <p>
* <b>Important</b>: This is a rather computation-heavy operation. Therefore, this operation is
* not repeated after an agent was successfully installed for the first time. Instead, the previous
* instrumentation instance is returned. However, invoking this method requires synchronization
* such that subsequently to an installation, {@link ByteBuddyAgent#getInstrumentation()} should
* be invoked instead.
* </p>
*
* @return An instrumentation instance representing the currently running JVM.
*/
public static Instrumentation install() {
return install(AttachmentProvider.DEFAULT);
}
/**
* Installs a Java agent using the Java attach API. This API is available under different
* access routes for different JVMs and JVM versions or it might not be available at all.
* If a Java agent cannot be installed by using the supplied attachment provider, an
* {@link IllegalStateException} is thrown. The same happens if the default process provider
* cannot resolve a process id for the current VM.
*
* @param attachmentProvider The attachment provider to use for the installation.
* @return An instrumentation instance representing the currently running JVM.
*/
public static Instrumentation install(AttachmentProvider attachmentProvider) {
return install(attachmentProvider, ProcessProvider.ForCurrentVm.INSTANCE);
}
/**
* Installs a Java agent using the Java attach API. This API is available under different
* access routes for different JVMs and JVM versions or it might not be available at all.
* If a Java agent cannot be installed by using the supplied process provider, an
* {@link IllegalStateException} is thrown. The same happens if the default attachment
* provider cannot be used.
*
* @param processProvider The provider for the current JVM's process id.
* @return An instrumentation instance representing the currently running JVM.
*/
public static Instrumentation install(ProcessProvider processProvider) {
return install(AttachmentProvider.DEFAULT, processProvider);
}
/**
* Installs a Java agent using the Java attach API. This API is available under different
* access routes for different JVMs and JVM versions or it might not be available at all.
* If a Java agent cannot be installed by using the supplied attachment provider and process
* provider, an {@link IllegalStateException} is thrown.
*
* @param attachmentProvider The attachment provider to use for the installation.
* @param processProvider The provider for the current JVM's process id.
* @return An instrumentation instance representing the currently running JVM.
*/
public static synchronized Instrumentation install(AttachmentProvider attachmentProvider, ProcessProvider processProvider) {
Instrumentation instrumentation = doGetInstrumentation();
if (instrumentation != null) {
return instrumentation;
}
install(attachmentProvider, processProvider.resolve(), WITHOUT_ARGUMENT, AgentProvider.ForByteBuddyAgent.INSTANCE);
return doGetInstrumentation();
}
/**
* Installs a Java agent on a target VM.
*
* @param attachmentProvider The attachment provider to use.
* @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.
*/
private static void install(AttachmentProvider attachmentProvider, String processId, String argument, AgentProvider agentProvider) {
AttachmentProvider.Accessor attachmentAccessor = attachmentProvider.attempt();
if (!attachmentAccessor.isAvailable()) {
throw new IllegalStateException("No compatible attachment provider is not available");
}
try {
if (ATTACHMENT_TYPE_EVALUATOR.requiresExternalAttachment(processId)) {
installExternal(attachmentAccessor.getExternalAttachment(), processId, agentProvider.resolve(), argument);
} else {
Attacher.install(attachmentAccessor.getVirtualMachineType(), processId, agentProvider.resolve(), argument);
}
} catch (RuntimeException exception) {
throw exception;
} catch (Exception exception) {
throw new IllegalStateException("Error during attachment using: " + attachmentProvider, exception);
}
}
/**
* Installs a Java agent to the current VM via an external process. This is typically required starting with OpenJDK 9
* when the {@code jdk.attach.allowAttachSelf} property is set to {@code false} what is the default setting.
*
* @param externalAttachment A description of the external attachment.
* @param processId The process id of the current process.
* @param agent The Java agent to install.
* @param argument The argument to provide to the agent or {@code null} if no argument should be supplied.
* @throws Exception If an exception occurs during the attachment or the external process fails the attachment.
*/
private static void installExternal(AttachmentProvider.Accessor.ExternalAttachment externalAttachment,
String processId,
File agent,
String argument) throws Exception {
InputStream inputStream = Attacher.class.getResourceAsStream('/' + Attacher.class.getName().replace('.', '/') + CLASS_FILE_EXTENSION);
if (inputStream == null) {
throw new IllegalStateException("Cannot locate class file for Byte Buddy installation process");
}
File attachmentJar = null;
try {
try {
attachmentJar = File.createTempFile(ATTACHER_FILE_NAME, JAR_FILE_EXTENSION);
JarOutputStream jarOutputStream = new JarOutputStream(new FileOutputStream(attachmentJar));
try {
jarOutputStream.putNextEntry(new JarEntry(Attacher.class.getName().replace('.', '/') + CLASS_FILE_EXTENSION));
byte[] buffer = new byte[BUFFER_SIZE];
int index;
while ((index = inputStream.read(buffer)) != END_OF_FILE) {
jarOutputStream.write(buffer, START_INDEX, index);
}
jarOutputStream.closeEntry();
} finally {
jarOutputStream.close();
}
} finally {
inputStream.close();
}
StringBuilder classPath = new StringBuilder().append('"').append(attachmentJar.getAbsolutePath()).append('"');
for (File jar : externalAttachment.getClassPath()) {
classPath.append(File.pathSeparatorChar).append('"').append(jar.getAbsolutePath()).append('"');
}
if (new ProcessBuilder(System.getProperty(JAVA_HOME)
+ File.separatorChar + "bin"
+ File.separatorChar + (System.getProperty(OS_NAME, "").toLowerCase(Locale.US).contains("windows") ? "java.exe" : "java"),
CLASS_PATH_ARGUMENT,
classPath.toString(),
Attacher.class.getName(),
externalAttachment.getVirtualMachineType(),
processId,
"\"" + agent.getAbsolutePath() + "\"",
argument == null ? "" : ("=" + argument)).start().waitFor() != SUCCESSFUL_ATTACH) {
throw new IllegalStateException("Could not self-attach to current VM using external process");
}
} finally {
if (attachmentJar != null && !attachmentJar.delete()) {
Logger.getAnonymousLogger().warning("Could not delete attachment jar: " + attachmentJar);
}
}
}
/**
* Performs the actual lookup of the {@link java.lang.instrument.Instrumentation} from an installed
* Byte Buddy agent.
*
* @return The Byte Buddy agent's {@link java.lang.instrument.Instrumentation} instance.
*/
@SuppressFBWarnings(value = "REC_CATCH_EXCEPTION", justification = "Legal outcome where reflection communicates errors by throwing an exception")
private static Instrumentation doGetInstrumentation() {
try {
return (Instrumentation) ClassLoader.getSystemClassLoader()
.loadClass(Installer.class.getName())
.getMethod(INSTRUMENTATION_METHOD)
.invoke(STATIC_MEMBER);
} catch (Exception ignored) {
return UNAVAILABLE;
}
}
/**
* An attachment provider is responsible for making the Java attachment API available.
*/
@SuppressFBWarnings(value = "IC_SUPERCLASS_USES_SUBCLASS_DURING_INITIALIZATION", justification = "Safe initialization is implied")
public interface AttachmentProvider {
/**
* The default attachment provider to be used.
*/
AttachmentProvider DEFAULT = new Compound(ForJigsawVm.INSTANCE,
ForJ9Vm.INSTANCE,
ForToolsJarVm.JVM_ROOT,
ForToolsJarVm.JDK_ROOT,
ForToolsJarVm.MACINTOSH,
ForUnixHotSpotVm.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 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;
@Override
public boolean isAvailable() {
return false;
}
@Override
public Class<?> getVirtualMachineType() {
throw new IllegalStateException("Cannot read the virtual machine type for an unavailable accessor");
}
@Override
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.
*/
@EqualsAndHashCode
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<File> 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<File> 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<File> getClassPath() {
return classPath;
}
}
/**
* A simple implementation of an accessible accessor.
*/
@EqualsAndHashCode
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;
}
/**
* <p>
* 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.
* </p>
* <p>
* This accessor is supposed to work on any implementation of the OpenJDK or Oracle JDK.
* </p>
*
* @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(classLoader.loadClass(VIRTUAL_MACHINE_TYPE_NAME),
Arrays.asList(classPath));
} catch (ClassNotFoundException ignored) {
return Unavailable.INSTANCE;
}
}
/**
* <p>
* 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.
* </p>
* <p>
* This accessor is supposed to work on any implementation of IBM's J9.
* </p>
*
* @return An appropriate accessor.
*/
public static Accessor ofJ9() {
try {
return new Simple.WithExternalAttachment(ClassLoader.getSystemClassLoader().loadClass(VIRTUAL_MACHINE_TYPE_NAME_J9),
Collections.<File>emptyList());
} catch (ClassNotFoundException ignored) {
return Unavailable.INSTANCE;
}
}
@Override
public boolean isAvailable() {
return true;
}
@Override
public Class<?> getVirtualMachineType() {
return virtualMachineType;
}
/**
* A simple implementation of an accessible accessor that allows for external attachment.
*/
@EqualsAndHashCode(callSuper = true)
protected static class WithExternalAttachment extends Simple {
/**
* The class path required for loading the virtual machine type.
*/
private final List<File> 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<File> classPath) {
super(virtualMachineType);
this.classPath = classPath;
}
@Override
public ExternalAttachment getExternalAttachment() {
return new ExternalAttachment(virtualMachineType.getName(), classPath);
}
}
/**
* A simple implementation of an accessible accessor that does not allow for external attachment.
*/
@EqualsAndHashCode(callSuper = true)
protected static class WithoutExternalAttachment extends Simple {
/**
* Creates a new simple accessor that does not allow for external attachment.
*
* @param virtualMachineType A {@code VirtualMachine} class.
*/
public WithoutExternalAttachment(Class<?> virtualMachineType) {
super(virtualMachineType);
}
@Override
public ExternalAttachment getExternalAttachment() {
throw new IllegalStateException("Cannot read the virtual machine type for an unavailable accessor");
}
}
}
}
/**
* An attachment provider that locates the attach API directly from the system class loader.
*/
enum ForJigsawVm implements AttachmentProvider {
/**
* The singleton instance.
*/
INSTANCE;
@Override
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;
@Override
public Accessor attempt() {
return Accessor.Simple.ofJ9();
}
}
/**
* An attachment provider that is dependant on the existence of a <i>tools.jar</i> file on the local
* file system.
*/
enum ForToolsJarVm implements AttachmentProvider {
/**
* An attachment provider that locates the <i>tools.jar</i> from a Java home directory.
*/
JVM_ROOT("../lib/tools.jar"),
/**
* An attachment provider that locates the <i>tools.jar</i> from a Java installation directory.
* In practice, several virtual machines do not return the JRE's location for the
* <i>java.home</i> property against the property's specification.
*/
JDK_ROOT("lib/tools.jar"),
/**
* An attachment provider that locates the <i>tools.jar</i> 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 <i>tools.jar</i> file, starting from the Java home directory.
*/
private final String toolsJarPath;
/**
* Creates a new attachment provider that loads the virtual machine class from the <i>tools.jar</i>.
*
* @param toolsJarPath The path to the <i>tools.jar</i> file, starting from the Java home directory.
*/
ForToolsJarVm(String toolsJarPath) {
this.toolsJarPath = toolsJarPath;
}
@Override
@SuppressFBWarnings(value = "DP_CREATE_CLASSLOADER_INSIDE_DO_PRIVILEGED", justification = "Privilege is explicit user responsibility")
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 using a custom protocol implementation for HotSpot on Unix.
*/
enum ForUnixHotSpotVm implements AttachmentProvider {
/**
* The singleton instance.
*/
INSTANCE;
@Override
public Accessor attempt() {
try {
return new Accessor.Simple.WithoutExternalAttachment(VirtualMachine.ForHotSpot.OnUnix.assertAvailability());
} 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.
*/
@EqualsAndHashCode
class Compound implements AttachmentProvider {
/**
* A list of attachment providers in the order of their application.
*/
private final List<AttachmentProvider> 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<? extends AttachmentProvider> attachmentProviders) {
this.attachmentProviders = new ArrayList<AttachmentProvider>();
for (AttachmentProvider attachmentProvider : attachmentProviders) {
if (attachmentProvider instanceof Compound) {
this.attachmentProviders.addAll(((Compound) attachmentProvider).attachmentProviders);
} else {
this.attachmentProviders.add(attachmentProvider);
}
}
}
@Override
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();
}
@Override
public String resolve() {
return dispatcher.resolve();
}
/**
* A process provider for a legacy VM that reads the process id from its JMX properties.
*/
protected enum ForLegacyVm implements ProcessProvider {
/**
* The singleton instance.
*/
INSTANCE;
@Override
public String resolve() {
String runtimeName = ManagementFactory.getRuntimeMXBean().getName();
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.
*/
@EqualsAndHashCode
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.
*/
@SuppressFBWarnings(value = "REC_CATCH_EXCEPTION", justification = "Exception should not be rethrown but trigger a fallback")
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;
}
}
@Override
public String resolve() {
try {
return pid.invoke(current.invoke(STATIC_MEMBER)).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.getCause());
}
}
}
}
}
/**
* 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 for a temporary Byte Buddy agent.
*/
enum ForByteBuddyAgent implements AgentProvider {
/**
* The singleton instance.
*/
INSTANCE;
/**
* The default prefix of the Byte Buddy agent jar file.
*/
private static final String AGENT_FILE_NAME = "byteBuddyAgent";
/**
* The jar file extension.
*/
private static final String JAR_FILE_EXTENSION = ".jar";
@Override
public File resolve() throws IOException {
File agentJar;
InputStream inputStream = Installer.class.getResourceAsStream('/' + Installer.class.getName().replace('.', '/') + CLASS_FILE_EXTENSION);
if (inputStream == null) {
throw new IllegalStateException("Cannot locate class file for Byte Buddy installer");
}
try {
agentJar = File.createTempFile(AGENT_FILE_NAME, JAR_FILE_EXTENSION);
agentJar.deleteOnExit(); // Agent jar is required until VM shutdown due to lazy class loading.
Manifest manifest = new Manifest();
manifest.getMainAttributes().put(Attributes.Name.MANIFEST_VERSION, MANIFEST_VERSION_VALUE);
manifest.getMainAttributes().put(new Attributes.Name(AGENT_CLASS_PROPERTY), Installer.class.getName());
manifest.getMainAttributes().put(new Attributes.Name(CAN_REDEFINE_CLASSES_PROPERTY), Boolean.TRUE.toString());
manifest.getMainAttributes().put(new Attributes.Name(CAN_RETRANSFORM_CLASSES_PROPERTY), Boolean.TRUE.toString());
manifest.getMainAttributes().put(new Attributes.Name(CAN_SET_NATIVE_METHOD_PREFIX), Boolean.TRUE.toString());
JarOutputStream jarOutputStream = new JarOutputStream(new FileOutputStream(agentJar), manifest);
try {
jarOutputStream.putNextEntry(new JarEntry(Installer.class.getName().replace('.', '/') + CLASS_FILE_EXTENSION));
byte[] buffer = new byte[BUFFER_SIZE];
int index;
while ((index = inputStream.read(buffer)) != END_OF_FILE) {
jarOutputStream.write(buffer, START_INDEX, index);
}
jarOutputStream.closeEntry();
} finally {
jarOutputStream.close();
}
} finally {
inputStream.close();
}
return agentJar;
}
}
/**
* An agent provider that supplies an existing agent that is not deleted after attachment.
*/
@EqualsAndHashCode
class ForExistingAgent implements AgentProvider {
/**
* The supplied agent.
*/
private File agent;
/**
* Creates an agent provider for an existing agent.
*
* @param agent The supplied agent.
*/
protected ForExistingAgent(File agent) {
this.agent = agent;
}
@Override
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<AttachmentTypeEvaluator> {
/**
* 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";
@Override
@SuppressFBWarnings(value = "REC_CATCH_EXCEPTION", justification = "Exception should not be rethrown but trigger a fallback")
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;
@Override
public boolean requiresExternalAttachment(String processId) {
return false;
}
}
/**
* An attachment type evaluator that checks a process id against the current process id.
*/
@EqualsAndHashCode
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 getPid;
/**
* Creates a new attachment type evaluator.
*
* @param current The {@code java.lang.ProcessHandle#current()} method.
* @param getPid The {@code java.lang.ProcessHandle#pid()} method.
*/
protected ForJava9CapableVm(Method current, Method getPid) {
this.current = current;
this.getPid = getPid;
}
@Override
public boolean requiresExternalAttachment(String processId) {
try {
return getPid.invoke(current.invoke(STATIC_MEMBER)).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.getCause());
}
}
}
}
}