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Use a custom classloader to load everything
This means that we shouldn't need to worry about things like `Class.forName` being called and getting the system classloader. This, in turn, allows us to monkey around with the classpath at runtime, which opens up all sorts of possibilities.
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176 changes: 176 additions & 0 deletions
176
java/server/src/org/openqa/selenium/grid/Bootstrap.java
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| // Licensed to the Software Freedom Conservancy (SFC) under one | ||
| // or more contributor license agreements. See the NOTICE file | ||
| // distributed with this work for additional information | ||
| // regarding copyright ownership. The SFC licenses this file | ||
| // to you under the Apache License, Version 2.0 (the | ||
| // "License"); you may not use this file except in compliance | ||
| // with the License. You may obtain a copy of the License at | ||
| // | ||
| // http://www.apache.org/licenses/LICENSE-2.0 | ||
| // | ||
| // Unless required by applicable law or agreed to in writing, | ||
| // software distributed under the License is distributed on an | ||
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY | ||
| // KIND, either express or implied. See the License for the | ||
| // specific language governing permissions and limitations | ||
| // under the License. | ||
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| package org.openqa.selenium.grid; | ||
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| import java.io.BufferedInputStream; | ||
| import java.io.ByteArrayOutputStream; | ||
| import java.io.File; | ||
| import java.io.IOException; | ||
| import java.io.InputStream; | ||
| import java.io.UncheckedIOException; | ||
| 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.ArrayList; | ||
| import java.util.HashSet; | ||
| import java.util.List; | ||
| import java.util.Set; | ||
| import java.util.logging.Level; | ||
| import java.util.logging.Logger; | ||
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| public class Bootstrap { | ||
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| private static final String MAIN_CLASS = Bootstrap.class.getPackage().getName() + ".Main"; | ||
| private static final Logger LOG = Logger.getLogger(Bootstrap.class.getName()); | ||
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| public static void main(String[] args) { | ||
| ClassLoader classLoader = Bootstrap.class.getClassLoader(); | ||
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| if (args.length == 0) { | ||
| runMain(classLoader, args); | ||
| } | ||
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| if ("--ext".equals(args[0])) { | ||
| if (args.length < 2) { | ||
| runMain(classLoader, args); | ||
| } | ||
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| ClassLoader parent = createExtendedClassLoader(args[1]); | ||
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| String[] remainingArgs = new String[args.length - 2]; | ||
| System.arraycopy(args, 2, remainingArgs, 0, args.length - 2); | ||
| args = remainingArgs; | ||
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| classLoader = new PossessiveClassLoader(parent); | ||
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| // Ensure that we use our freshly minted classloader by default. | ||
| Thread.currentThread().setContextClassLoader(classLoader); | ||
| } | ||
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| runMain(classLoader, args); | ||
| } | ||
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| private static void runMain(ClassLoader loader, String[] args) { | ||
| try { | ||
| Class<?> clazz = loader.loadClass(MAIN_CLASS); | ||
| Method main = clazz.getMethod("main", String[].class); | ||
| main.invoke(null, new Object[] {args}); | ||
| } catch (ReflectiveOperationException e) { | ||
| e.printStackTrace(); | ||
| System.err.println("Unable to load main class"); | ||
| } | ||
| } | ||
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| private static ClassLoader createExtendedClassLoader(String ext) { | ||
| List<File> jars = new ArrayList<>(); | ||
| for (String part : ext.split(File.pathSeparator)) { | ||
| File file = new File(part); | ||
| if (!file.exists()) { | ||
| LOG.warning("Extension file or directory does not exist: " + file); | ||
| continue; | ||
| } | ||
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| if (file.isDirectory()) { | ||
| File[] files = file.listFiles(); | ||
| if (files == null) { | ||
| LOG.warning("Cannot list files in directory: " + file); | ||
| } else { | ||
| for (File subdirFile : files) { | ||
| if (subdirFile.isFile() && subdirFile.getName().endsWith(".jar")) { | ||
| jars.add(subdirFile); | ||
| } | ||
| } | ||
| } | ||
| } else { | ||
| jars.add(file); | ||
| } | ||
| } | ||
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| URL[] jarUrls = jars.stream() | ||
| .map(file -> { | ||
| try { | ||
| return file.toURI().toURL(); | ||
| } catch (MalformedURLException e) { | ||
| LOG.log(Level.SEVERE, "Unable to find JAR file " + file, e); | ||
| throw new UncheckedIOException(e); | ||
| } | ||
| }) | ||
| .toArray(URL[]::new); | ||
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| return AccessController.doPrivileged((PrivilegedAction<URLClassLoader>) () -> | ||
| new URLClassLoader(jarUrls, Bootstrap.class.getClassLoader())); | ||
| } | ||
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| private static class PossessiveClassLoader extends ClassLoader { | ||
| private final ClassLoader delegate; | ||
| private final Set<String> blessed; | ||
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| PossessiveClassLoader(ClassLoader delegate) { | ||
| super(delegate); | ||
| this.delegate = delegate; | ||
| blessed = new HashSet<>(); | ||
| blessed.add("java."); | ||
| blessed.add("javax."); | ||
| blessed.add("sun."); | ||
| blessed.add("jdk."); | ||
| } | ||
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| @Override | ||
| protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException { | ||
| for (String prefix : blessed) { | ||
| if (name.startsWith(prefix)) { | ||
| return super.loadClass(name, resolve); | ||
| } | ||
| } | ||
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| Class<?> clazz = findLoadedClass(name); | ||
| if (clazz != null) { | ||
| return clazz; | ||
| } | ||
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| URL resource = delegate.getResource(name.replaceAll("\\.", "/") + ".class"); | ||
| if (resource == null) { | ||
| throw new ClassNotFoundException("Unable to find " + name); | ||
| } | ||
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| ByteArrayOutputStream bos = new ByteArrayOutputStream(); | ||
| try (InputStream is = resource.openStream(); | ||
| BufferedInputStream bis = new BufferedInputStream(is)) { | ||
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| int read; | ||
| byte[] bytes = new byte[4096]; | ||
| while ((read = bis.read(bytes, 0, bytes.length)) != -1) { | ||
| bos.write(bytes, 0, read); | ||
| } | ||
| } catch (IOException e) { | ||
| throw new ClassNotFoundException("Could not load " + name, e); | ||
| } | ||
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| byte[] rawClass = bos.toByteArray(); | ||
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| Class<?> defined = defineClass(name, rawClass, 0, rawClass.length); | ||
| if (resolve) { | ||
| resolveClass(defined); | ||
| } | ||
| return defined; | ||
| } | ||
| } | ||
| } |
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