I am trying to load classes from an agent implemented using ByteBuddy. I have a class defined in the agent and want to load it in the target program. here is what my transformer looks like:
public class ClassLoaderTransformer implements AgentBuilder.Transformer {
private final Class<?> targetClass;
public ClassLoaderTransformer(Class<?> targetClass) {
this.targetClass = targetClass;
}
@Override
public DynamicType.Builder<?> transform(DynamicType.Builder<?> builder, TypeDescription typeDescription, ClassLoader classLoader, JavaModule module) {
try {
final Class<?> aClass = Class.forName(typeDescription.getName());
resolveClassLoadingStrategy(aClass).load(classLoader, singletonMap(
new TypeDescription.ForLoadedType(targetClass),
ClassFileLocator.ForClassLoader.read(targetClass)
));
} catch (Exception e){
System.out.println("Something went terribly wrong: " + e.getMessage());
}
return builder;
}
private static ClassLoadingStrategy<ClassLoader> resolveClassLoadingStrategy(Class<?> targetClass) throws IllegalAccessException {
if ( !ClassInjector.UsingLookup.isAvailable() ) {
return new ClassLoadingStrategy.ForUnsafeInjection(targetClass.getProtectionDomain() );
}
MethodHandles.Lookup lookup = MethodHandles.lookup();
MethodHandles.Lookup privateLookup = MethodHandles.privateLookupIn(targetClass, lookup);
return ClassLoadingStrategy.UsingLookup.of( privateLookup );
}
}
However, this code is not working. It throws the following error:
tech.ikora.seleniumagent.helpers.SourcePageFetcher must be defined in the same package as org.openqa.selenium.remote.RemoteWebDriver
and the stack traces looks like this:
java.lang.IllegalArgumentException: tech.ikora.seleniumagent.helpers.SourcePageFetcher must be defined in the same package as org.openqa.selenium.remote.RemoteWebDriver
at net.bytebuddy.dynamic.loading.ClassInjector$UsingLookup.injectRaw(ClassInjector.java:1414)
at net.bytebuddy.dynamic.loading.ClassInjector$AbstractBase.inject(ClassInjector.java:110)
at net.bytebuddy.dynamic.loading.ClassLoadingStrategy$UsingLookup.load(ClassLoadingStrategy.java:492)
at tech.ikora.seleniumagent.ClassLoaderTransformer.transform(ClassLoaderTransformer.java:27)
at net.bytebuddy.agent.builder.AgentBuilder$Default$ExecutingTransformer.doTransform(AgentBuilder.java:10364)
at net.bytebuddy.agent.builder.AgentBuilder$Default$ExecutingTransformer.transform(AgentBuilder.java:10302)
at net.bytebuddy.agent.builder.AgentBuilder$Default$ExecutingTransformer.access$1600(AgentBuilder.java:10068)
at net.bytebuddy.agent.builder.AgentBuilder$Default$ExecutingTransformer$Java9CapableVmDispatcher.run(AgentBuilder.java:10761)
at net.bytebuddy.agent.builder.AgentBuilder$Default$ExecutingTransformer$Java9CapableVmDispatcher.run(AgentBuilder.java:10699)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:389)
at net.bytebuddy.agent.builder.AgentBuilder$Default$ExecutingTransformer.transform(AgentBuilder.java:10258)
at net.bytebuddy.agent.builder.AgentBuilder$Default$ExecutingTransformer$ByteBuddy$ModuleSupport.transform(Unknown Source)
at java.instrument/sun.instrument.TransformerManager.transform(TransformerManager.java:188)
at java.instrument/sun.instrument.InstrumentationImpl.transform(InstrumentationImpl.java:563)
at java.base/java.lang.ClassLoader.defineClass1(Native Method)
at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016)
at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:151)
at java.base/java.net.URLClassLoader.defineClass(URLClassLoader.java:515)
at java.base/java.net.URLClassLoader$1.run(URLClassLoader.java:423)
at java.base/java.net.URLClassLoader$1.run(URLClassLoader.java:417)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:689)
at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:416)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:588)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
at org.apache.maven.surefire.booter.IsolatedClassLoader.loadClass(IsolatedClassLoader.java:97)
at java.base/java.lang.ClassLoader.defineClass1(Native Method)
at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016)
at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:151)
at java.base/java.net.URLClassLoader.defineClass(URLClassLoader.java:515)
at java.base/java.net.URLClassLoader$1.run(URLClassLoader.java:423)
at java.base/java.net.URLClassLoader$1.run(URLClassLoader.java:417)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:689)
at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:416)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:588)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
at org.apache.maven.surefire.booter.IsolatedClassLoader.loadClass(IsolatedClassLoader.java:97)
at base.BaseTest.setup(BaseTest.java:31)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:567)
at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:132)
at org.testng.internal.MethodInvocationHelper.invokeMethodConsideringTimeout(MethodInvocationHelper.java:61)
at org.testng.internal.ConfigInvoker.invokeConfigurationMethod(ConfigInvoker.java:366)
at org.testng.internal.ConfigInvoker.invokeConfigurations(ConfigInvoker.java:320)
at org.testng.internal.TestMethodWorker.invokeBeforeClassMethods(TestMethodWorker.java:176)
at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:122)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1540)
at org.testng.TestRunner.privateRun(TestRunner.java:764)
at org.testng.TestRunner.run(TestRunner.java:585)
at org.testng.SuiteRunner.runTest(SuiteRunner.java:384)
at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:378)
at org.testng.SuiteRunner.privateRun(SuiteRunner.java:337)
at org.testng.SuiteRunner.run(SuiteRunner.java:286)
at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:53)
at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:96)
at org.testng.TestNG.runSuitesSequentially(TestNG.java:1218)
at org.testng.TestNG.runSuitesLocally(TestNG.java:1140)
at org.testng.TestNG.runSuites(TestNG.java:1069)
at org.testng.TestNG.run(TestNG.java:1037)
at org.apache.maven.surefire.testng.TestNGExecutor.run(TestNGExecutor.java:77)
at org.apache.maven.surefire.testng.TestNGDirectoryTestSuite.executeMulti(TestNGDirectoryTestSuite.java:159)
at org.apache.maven.surefire.testng.TestNGDirectoryTestSuite.execute(TestNGDirectoryTestSuite.java:99)
at org.apache.maven.surefire.testng.TestNGProvider.invoke(TestNGProvider.java:106)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:567)
at org.apache.maven.surefire.util.ReflectionUtils.invokeMethodWithArray(ReflectionUtils.java:189)
at org.apache.maven.surefire.booter.ProviderFactory$ProviderProxy.invoke(ProviderFactory.java:165)
at org.apache.maven.surefire.booter.ProviderFactory.invokeProvider(ProviderFactory.java:85)
at org.apache.maven.plugin.surefire.InPluginVMSurefireStarter.runSuitesInProcess(InPluginVMSurefireStarter.java:80)
at org.apache.maven.plugin.surefire.AbstractSurefireMojo.executeProvider(AbstractSurefireMojo.java:724)
at org.apache.maven.plugin.surefire.AbstractSurefireMojo.executeAllProviders(AbstractSurefireMojo.java:682)
at org.apache.maven.plugin.surefire.AbstractSurefireMojo.executeAfterPreconditionsChecked(AbstractSurefireMojo.java:648)
at org.apache.maven.plugin.surefire.AbstractSurefireMojo.execute(AbstractSurefireMojo.java:586)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:137)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:210)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:156)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:148)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:117)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:81)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:56)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:305)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:192)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:105)
at org.apache.maven.cli.MavenCli.execute(MavenCli.java:957)
at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:289)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:193)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:567)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:282)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:225)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:406)
at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:347)
In this example, SourcePageFetcher is the targetClass and RemoveWebDriver is the class provided by the TypeDescription.
The goal of this class loader is to load classes that would be helpers to some of the Advice that I created to instrument my code. Should I try to use the ClassInjector in another way? Or am I seeing the problem in the wrong way or should I just use another ClassLoadingStrategy?
As the error message suggests: a lookup only allows you to define classes in packages of the specified lookup's class. If the package differs as it does for you:
tech.ikora.seleniumagent.helpers
org.openqa.selenium.remote
the JVM would not allow for it. From an agent, you can however also use the UsingUnsafe strategy as the Instrumentation instance can grant you access to the JVM internals. Otherwise, you'd need to hook your injection to a class in the right package.
Note that you can rather use the ClassInjector directly instead of using a ClassLoadingStrategy.