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/*
* Copyright (C) 2022 The Project Lombok Authors.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package lombok.launch;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.lang.instrument.Instrumentation;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.ProtectionDomain;
import java.util.jar.JarFile;
/**
* This Java agent does not transform bytecode, but acts as a watcher that can
* figure out when it is appropriate to load Lombok itself within a Maven
* execution.
*
* It relies on several facts:
* <ul>
* <li>maven-compiler-plugin contains an {@code AbstractCompilerMojo} class that
* compiler instances extend.
* <li>Maven loaders are {@code ClassRealms}, which extend {@code URLClassLoader}.
* <li>Each plugin dependency in the <em>pom.xml </em>is represented as a file URL on the
* ClassRealm that points to the artifact.
* <li>URLs to Maven artifacts contain the group and artifact ids
* ({@code [...]/groupid/artifactid/ver/artifactid-ver.jar}).
* <li>The Lombok Java agent class is {@code lombok.launch.Agent}.
* </ul>
* Given all of the above, the transformer simply waits for {@code AbstractCompilerMojo}
* to be loaded, then uses the loader to find the path to the Lombok jar file,
* and finally loads the Lombok agent using reflection.
*/
public final class MavenEcjBootstrapAgent {
private static final String MAVEN_COMPILER_TRIGGER_CLASS = "org/apache/maven/plugin/compiler/AbstractCompilerMojo";
private static final String LOMBOK_URL_IDENTIFIER = "/org/projectlombok/lombok/";
private static final String LOMBOK_AGENT_CLASS = "lombok.launch.Agent";
private static final byte[] NOT_TRANSFORMED = null;
private MavenEcjBootstrapAgent() {}
public static void premain(final String agentArgs, final Instrumentation instrumentation) {
instrumentation.addTransformer(new ClassFileTransformer() {
@Override public byte[] transform(final ClassLoader loader, final String className, final Class<?> cbr, final ProtectionDomain pd, final byte[] cfb) throws IllegalClassFormatException {
if (MAVEN_COMPILER_TRIGGER_CLASS.equals(className)) {
for (final URL url : ((URLClassLoader) loader).getURLs()) {
if (url.getPath().contains(LOMBOK_URL_IDENTIFIER)) {
try {
instrumentation.appendToSystemClassLoaderSearch(new JarFile(url.getPath()));
MavenEcjBootstrapAgent.class.getClassLoader().loadClass(LOMBOK_AGENT_CLASS).getDeclaredMethod("premain", String.class, Instrumentation.class).invoke(null, agentArgs, instrumentation);
instrumentation.removeTransformer(this);
break;
} catch (Exception e) {
// There are no appropriate loggers available at
// this point in time.
e.printStackTrace(System.err);
}
}
}
}
return NOT_TRANSFORMED;
}
});
}
}
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