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ReflectionClassPathAppender on Java 16+

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Luck 2021-08-17 21:29:10 +01:00
parent ee6aa47d99
commit b232cb94b4
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3 changed files with 194 additions and 64 deletions
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4
common/src/main/java/me/lucko/luckperms/common/extension/SimpleExtensionManager.java
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@ -28,7 +28,7 @@ package me.lucko.luckperms.common.extension;
import com.google.gson.JsonObject;
import me.lucko.luckperms.common.plugin.LuckPermsPlugin;
import me.lucko.luckperms.common.plugin.classpath.ReflectionClassPathAppender;
import me.lucko.luckperms.common.plugin.classpath.URLClassLoaderAccess;
import me.lucko.luckperms.common.util.gson.GsonProvider;
import net.luckperms.api.LuckPerms;
@ -206,7 +206,7 @@ public class SimpleExtensionManager implements ExtensionManager, AutoCloseable {
throw new RuntimeException("useParentClassLoader is true but parent is not a URLClassLoader");
}
ReflectionClassPathAppender.addUrl(((URLClassLoader) parentClassLoader), path.toUri().toURL());
URLClassLoaderAccess.create(((URLClassLoader) parentClassLoader)).addURL(path.toUri().toURL());
}
private static final class LoadedExtension {

66
common/src/main/java/me/lucko/luckperms/common/plugin/classpath/ReflectionClassPathAppender.java
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@ -27,56 +27,17 @@ package me.lucko.luckperms.common.plugin.classpath;
import me.lucko.luckperms.common.plugin.bootstrap.LuckPermsBootstrap;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.nio.file.Path;
@Deprecated // TODO: no longer works on Java 16 - Sponge needs to switch to JarInJar or find an API to add to classpath at runtime
public class ReflectionClassPathAppender implements ClassPathAppender {
private static final Method ADD_URL_METHOD;
static {
// If on Java 9+, open the URLClassLoader module to this module
// so we can access its API via reflection without producing a warning.
try {
openUrlClassLoaderModule();
} catch (Throwable e) {
// ignore
}
try {
ADD_URL_METHOD = URLClassLoader.class.getDeclaredMethod("addURL", URL.class);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
}
try {
ADD_URL_METHOD.setAccessible(true);
} catch (Throwable e) {
new RuntimeException("LuckPerms is unable to access the URLClassLoader#addURL method using reflection. \n" +
"You may be able to fix this problem by adding the following command-line argument " +
"directly after the 'java' command in your start script: \n'--add-opens java.base/java.lang=ALL-UNNAMED'", e).printStackTrace();
}
}
/**
* Adds the given {@link URL} to the class loader.
*
* @param classLoader the class loader
* @param url the url to add
*/
public static void addUrl(URLClassLoader classLoader, URL url) throws ReflectiveOperationException {
ADD_URL_METHOD.invoke(classLoader, url);
}
private final URLClassLoader classLoader;
private final URLClassLoaderAccess classLoaderAccess;
public ReflectionClassPathAppender(LuckPermsBootstrap bootstrap) throws IllegalStateException {
ClassLoader classLoader = bootstrap.getClass().getClassLoader();
if (classLoader instanceof URLClassLoader) {
this.classLoader = (URLClassLoader) classLoader;
this.classLoaderAccess = URLClassLoaderAccess.create((URLClassLoader) classLoader);
} else {
throw new IllegalStateException("ClassLoader is not instance of URLClassLoader");
}
@ -85,29 +46,10 @@ public class ReflectionClassPathAppender implements ClassPathAppender {
@Override
public void addJarToClasspath(Path file) {
try {
addUrl(this.classLoader, file.toUri().toURL());
} catch (ReflectiveOperationException | MalformedURLException e) {
this.classLoaderAccess.addURL(file.toUri().toURL());
} catch (MalformedURLException e) {
throw new RuntimeException(e);
}
}
private static void openUrlClassLoaderModule() throws Exception {
// This is effectively calling:
//
// URLClassLoader.class.getModule().addOpens(
// URLClassLoader.class.getPackageName(),
// ReflectionClassLoader.class.getModule()
// );
//
// We use reflection since we build against Java 8.
Class<?> moduleClass = Class.forName("java.lang.Module");
Method getModuleMethod = Class.class.getMethod("getModule");
Method addOpensMethod = moduleClass.getMethod("addOpens", String.class, moduleClass);
Object urlClassLoaderModule = getModuleMethod.invoke(URLClassLoader.class);
Object thisModule = getModuleMethod.invoke(ReflectionClassPathAppender.class);
addOpensMethod.invoke(urlClassLoaderModule, URLClassLoader.class.getPackage().getName(), thisModule);
}
}

188
common/src/main/java/me/lucko/luckperms/common/plugin/classpath/URLClassLoaderAccess.java Normal file
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@ -0,0 +1,188 @@
/*
* This file is part of LuckPerms, licensed under the MIT License.
*
* Copyright (c) lucko (Luck) <luck@lucko.me>
* Copyright (c) contributors
*
* 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 me.lucko.luckperms.common.plugin.classpath;
import org.checkerframework.checker.nullness.qual.NonNull;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.Collection;
/**
* Provides access to {@link URLClassLoader}#addURL.
*/
public abstract class URLClassLoaderAccess {
/**
* Creates a {@link URLClassLoaderAccess} for the given class loader.
*
* @param classLoader the class loader
* @return the access object
*/
public static URLClassLoaderAccess create(URLClassLoader classLoader) {
if (Reflection.isSupported()) {
return new Reflection(classLoader);
} else if (Unsafe.isSupported()) {
return new Unsafe(classLoader);
} else {
return Noop.INSTANCE;
}
}
private final URLClassLoader classLoader;
protected URLClassLoaderAccess(URLClassLoader classLoader) {
this.classLoader = classLoader;
}
/**
* Adds the given URL to the class loader.
*
* @param url the URL to add
*/
public abstract void addURL(@NonNull URL url);
private static void throwError(Throwable cause) throws UnsupportedOperationException {
throw new UnsupportedOperationException("LuckPerms is unable to inject into the plugin URLClassLoader.\n" +
"You may be able to fix this problem by adding the following command-line argument " +
"directly after the 'java' command in your start script: \n'--add-opens java.base/java.lang=ALL-UNNAMED'", cause);
}
/**
* Accesses using reflection, not supported on Java 9+.
*/
private static class Reflection extends URLClassLoaderAccess {
private static final Method ADD_URL_METHOD;
static {
Method addUrlMethod;
try {
addUrlMethod = URLClassLoader.class.getDeclaredMethod("addURL", URL.class);
addUrlMethod.setAccessible(true);
} catch (Exception e) {
addUrlMethod = null;
}
ADD_URL_METHOD = addUrlMethod;
}
private static boolean isSupported() {
return ADD_URL_METHOD != null;
}
Reflection(URLClassLoader classLoader) {
super(classLoader);
}
@Override
public void addURL(@NonNull URL url) {
try {
ADD_URL_METHOD.invoke(super.classLoader, url);
} catch (ReflectiveOperationException e) {
URLClassLoaderAccess.throwError(e);
}
}
}
/**
* Accesses using sun.misc.Unsafe, supported on Java 9+.
*
* @author Vaishnav Anil (https://github.com/slimjar/slimjar)
*/
private static class Unsafe extends URLClassLoaderAccess {
private static final sun.misc.Unsafe UNSAFE;
static {
sun.misc.Unsafe unsafe;
try {
Field unsafeField = sun.misc.Unsafe.class.getDeclaredField("theUnsafe");
unsafeField.setAccessible(true);
unsafe = (sun.misc.Unsafe) unsafeField.get(null);
} catch (Throwable t) {
unsafe = null;
}
UNSAFE = unsafe;
}
private static boolean isSupported() {
return UNSAFE != null;
}
private final Collection<URL> unopenedURLs;
private final Collection<URL> pathURLs;
@SuppressWarnings("unchecked")
Unsafe(URLClassLoader classLoader) {
super(classLoader);
Collection<URL> unopenedURLs;
Collection<URL> pathURLs;
try {
Object ucp = fetchField(URLClassLoader.class, classLoader, "ucp");
unopenedURLs = (Collection<URL>) fetchField(ucp.getClass(), ucp, "unopenedUrls");
pathURLs = (Collection<URL>) fetchField(ucp.getClass(), ucp, "path");
} catch (Throwable e) {
unopenedURLs = null;
pathURLs = null;
}
this.unopenedURLs = unopenedURLs;
this.pathURLs = pathURLs;
}
private static Object fetchField(final Class<?> clazz, final Object object, final String name) throws NoSuchFieldException {
Field field = clazz.getDeclaredField(name);
long offset = UNSAFE.objectFieldOffset(field);
return UNSAFE.getObject(object, offset);
}
@Override
public void addURL(@NonNull URL url) {
if (this.unopenedURLs == null || this.pathURLs == null) {
URLClassLoaderAccess.throwError(new NullPointerException("unopenedURLs or pathURLs"));
}
this.unopenedURLs.add(url);
this.pathURLs.add(url);
}
}
private static class Noop extends URLClassLoaderAccess {
private static final Noop INSTANCE = new Noop();
private Noop() {
super(null);
}
@Override
public void addURL(@NonNull URL url) {
URLClassLoaderAccess.throwError(null);
}
}
}