org.avaje.agentloader.AgentLoader Maven / Gradle / Ivy
package org.avaje.agentloader;
import com.sun.tools.attach.AttachNotSupportedException;
import com.sun.tools.attach.VirtualMachine;
import com.sun.tools.attach.VirtualMachineDescriptor;
import com.sun.tools.attach.spi.AttachProvider;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import sun.tools.attach.BsdVirtualMachine;
import sun.tools.attach.LinuxVirtualMachine;
import sun.tools.attach.SolarisVirtualMachine;
import sun.tools.attach.WindowsVirtualMachine;
import java.io.*;
import java.lang.management.ManagementFactory;
import java.lang.reflect.Field;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import java.util.jar.JarOutputStream;
/**
* Provides the ability to load an agent on a running process.
*
* author: Richard Vowles - http://gplus.to/RichardVowles
*/
public class AgentLoader {
private static final Logger log = LoggerFactory.getLogger(AgentLoader.class);
private static final List loaded = new ArrayList();
/**
* Buffer size used when extracting the agent (when it is embedded).
*/
private static final int IO_BUFFER_SIZE = 1024 * 4;
private static final String discoverPid() {
String nameOfRunningVM = ManagementFactory.getRuntimeMXBean().getName();
int p = nameOfRunningVM.indexOf('@');
return nameOfRunningVM.substring(0, p);
}
private static final AttachProvider ATTACH_PROVIDER = new AttachProvider() {
@Override
public String name() {
return null;
}
@Override
public String type() {
return null;
}
@Override
public VirtualMachine attachVirtualMachine(String id) {
return null;
}
@Override
public List listVirtualMachines() {
return null;
}
};
/**
* Load an agent providing the full file path.
*/
public static void loadAgent(String jarFilePath) {
loadAgent(jarFilePath, "");
}
/**
* Load an agent providing the full file path with parameters.
*/
public static void loadAgent(String jarFilePath, String params) {
log.info("dynamically loading javaagent for " + jarFilePath);
try {
String pid = discoverPid();
VirtualMachine vm;
if (AttachProvider.providers().isEmpty()) {
vm = getVirtualMachineImplementationFromEmbeddedOnes(pid);
} else {
vm = VirtualMachine.attach(pid);
}
vm.loadAgent(jarFilePath, params);
vm.detach();
} catch (Exception e) {
throw new RuntimeException(e);
}
}
/**
* Load the agent from the classpath using its name.
*/
public static void loadAgentFromClasspath(String agentName) {
loadAgentFromClasspath(agentName, "");
}
/**
* Load the agent from the classpath using its name and passing params.
*/
public synchronized static boolean loadAgentFromClasspath(String agentName, String params) {
if (loaded.contains(agentName)) {
// the agent is already loaded
return true;
}
try {
// Search for the agent jar in the classpath
if (AgentLoader.class.getClassLoader() instanceof URLClassLoader) {
URLClassLoader cl = (URLClassLoader) (AgentLoader.class.getClassLoader());
for (URL url : cl.getURLs()) {
if (isMatch(url, agentName)) {
// We have found the agent jar in the classpath
String fullName = url.toURI().getPath();
boolean isEmbedded = false;
if (isAgentEmbeddedInJar(url, fullName)) {
// extract the agent jar into a tmp directory for use
fullName = extractJar(url, agentName);
isEmbedded = true;
}
if (fullName != null && !loaded.contains(fullName)) {
if (fullName.startsWith("/") && isWindows()) {
fullName = fullName.substring(1);
}
try {
loadAgent(fullName, params);
loaded.add(fullName);
return true;
} finally {
if (isEmbedded) {
try {
new File(fullName).delete();
} catch (Exception ex) {
log.warn("Cannot delete Agent file from JVM temporary folder", ex);
}
}
}
}
}
}
}
// Agent not found and not loaded
return false;
} catch (URISyntaxException use) {
throw new RuntimeException(use);
}
}
/**
* Return true if the agent jar is embedded. In this case we extract it out into a tmp directory.
*/
private static boolean isAgentEmbeddedInJar(URL url, String fullName) {
return fullName == null && url.getProtocol().equals("jar") && url.getPath().contains("!/");
}
/**
* Check to see if this url/jar matches our agent name.
*/
private static boolean isMatch(URL url, String partial) {
String fullPath = url.getFile();
int lastSlash = fullPath.lastIndexOf('/');
if (lastSlash < 0) {
return false;
}
/**
* Use 'contains' so ignoring the version of the agent and offset of inner jar
*/
return fullPath.contains(partial);
}
private static final boolean isWindows() {
return File.separatorChar == '\\';
}
/**
* @return true if the path is an embedded JAR file.
*
* If it is an embedded JAR file, we only need to export it.
* Otherwise, we have to extract all class files, and package them into a JAR file.
*/
private static boolean isEmbededJar(String path) {
return path.endsWith(".jar!/");
}
/**
* This method will extract agent JAR file from URL path.
* Due to the package implementation, this method will cover two cases as below:
* Embedded Class Files: jar:file:path-to-filename.war!/WEB-INF/jar/jar-file/
* Embedded Jar Files: jar:file:path-to-filename.war!/WEB-INF/jar/jar-file!/
*
* @param path is full url entry in the classpath
* @param agentName is the agent name that we are trying to match
* @return null if it fails or a full path to the jar file if it succeeds
*/
public static String extractJar(URL path, String agentName) {
String fullPath = null;
OutputStream outputJar = null;
JarFile inputZip = null;
log.debug("Extracting agent {} from source {}", agentName, path.getPath());
try {
String[] jarNames = path.getPath().split(":");
String[] packageFileAndFileOffset = jarNames[1].split("!/");
// the full path of Final Agent Jar File
fullPath = System.getProperty("java.io.tmpdir") + "/" + agentName + ".jar";
String packageFile = packageFileAndFileOffset[0];
String fileOffset = packageFileAndFileOffset[1];
inputZip = new JarFile(packageFile);
boolean isJarFile = isEmbededJar(jarNames[1]);
outputJar = isJarFile ?
new FileOutputStream(fullPath) :
new JarOutputStream(new FileOutputStream(fullPath));
exportFile(inputZip, outputJar, fileOffset, isJarFile);
log.debug("Extracted agent to {}", fullPath);
} catch (Exception ex) {
log.error("Failed to export agent " + agentName, ex);
} finally {
if (outputJar != null) {
try {
outputJar.close();
} catch (IOException ioEx) {
log.error("Error closing Agent JarFile", ioEx);
}
}
if (inputZip != null) {
try {
inputZip.close();
} catch (IOException ioEx) {
log.error("Error closing input JarFile", ioEx);
}
}
}
return fullPath;
}
/**
* Export the file from source JarFile to target file
*
* @param source is the source Jar file
* @param target is the target file (either JarFile, or File)
* @param partial if offset of expected file in the source Jar file
* @param isJar is flag of expected file type
*
*/
protected static void exportFile(JarFile source, OutputStream target, String partial, boolean isJar) throws NoSuchFieldException, IllegalAccessException, IOException {
Enumeration entries = source.entries();
while (entries.hasMoreElements()) {
JarEntry entry = entries.nextElement();
if (entry.getName().startsWith(partial)) {
log.debug("copying {} to output", entry.getName());
if (isJar) {
// Only need to export a single JAR file
copyBytes(source.getInputStream(entry), target);
break;
} else {
// Need to extract all class files and put into a new JarFile
String internalName = entry.getName().substring(partial.length());
JarEntry ze = new JarEntry(entry);
Field f = ze.getClass().getSuperclass().getDeclaredField("name");
f.setAccessible(true);
f.set(ze, internalName);
try {
((JarOutputStream) target).putNextEntry(ze);
copyBytes(source.getInputStream(entry), target);
} finally {
((JarOutputStream) target).closeEntry();
}
}
}
}
}
/**
* Copy the bytes from input to output streams (using a 4K buffer).
*/
protected static long copyBytes(InputStream input, OutputStream output) throws IOException {
byte[] buffer = new byte[IO_BUFFER_SIZE];
long count = 0;
int n;
while (-1 != (n = input.read(buffer))) {
output.write(buffer, 0, n);
count += n;
}
return count;
}
private static VirtualMachine getVirtualMachineImplementationFromEmbeddedOnes(String pid) {
try {
if (isWindows()) {
return new WindowsVirtualMachine(ATTACH_PROVIDER, pid);
}
String osName = System.getProperty("os.name");
if (osName.startsWith("Linux") || osName.startsWith("LINUX")) {
return new LinuxVirtualMachine(ATTACH_PROVIDER, pid);
} else if (osName.startsWith("Mac OS X")) {
return new BsdVirtualMachine(ATTACH_PROVIDER, pid);
} else if (osName.startsWith("Solaris")) {
return new SolarisVirtualMachine(ATTACH_PROVIDER, pid);
}
} catch (AttachNotSupportedException e) {
throw new RuntimeException(e);
} catch (IOException e) {
throw new RuntimeException(e);
} catch (UnsatisfiedLinkError e) {
throw new IllegalStateException("Native library for Attach API not available in this JRE", e);
}
return null;
}
}