com.google.gwt.dev.url.CloseableJarHandlerFactory Maven / Gradle / Ivy
/*
* Copyright 2014 Google Inc.
*
* Licensed 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.
*/
package com.google.gwt.dev.url;
import java.io.IOException;
import java.net.URL;
import java.net.URLStreamHandler;
import java.net.URLStreamHandlerFactory;
/**
* A factory that constructs URL Stream Handlers and extends Jar protocol handling by making it
* possible to close all InputStreams for a given Zip file.
*
* This closing functionality makes it possible to run untrusted plugin code (for example
* Generators) and still guarantee that there will be no accidental attempts to read from old and
* deleted Zip files using stale InputStreams.
*/
public class CloseableJarHandlerFactory implements URLStreamHandlerFactory {
/**
* Takes over the URL connection opening system so that Zip file connections can be gathered and
* then closed before Zip files are replaced on disk. This avoids a JVM crash on Linux that can
* occur if a third party plugin (ie. Generator) fails to close its InputStreams.
*/
private static CloseableJarHandlerFactory closeableJarHandlerFactory;
/**
* Closes all InputStreams that were created by the URL system that point at the given Jar file.
*/
public static void closeStreams(String jarFilePath) throws IOException {
closeableJarHandlerFactory.closeableJarHandler.closeStreams(jarFilePath);
}
/**
* Ensures that the standard UrlStreamHandlerFactory has been replaced.
*/
public static synchronized void installOverride() {
if (closeableJarHandlerFactory == null) {
closeableJarHandlerFactory = new CloseableJarHandlerFactory();
URL.setURLStreamHandlerFactory(closeableJarHandlerFactory);
}
}
private static URLStreamHandler createHandlerForProtocol(String protocol) {
String className = String.format("sun.net.www.protocol.%s.Handler", protocol);
try {
return (URLStreamHandler) Class.forName(className).newInstance();
} catch (ClassNotFoundException e) {
throw new RuntimeException("Couldn't find handler for protocol: " + protocol);
} catch (InstantiationException e) {
throw new RuntimeException("Handler isn't not instantiable for protocol: " + protocol);
} catch (IllegalAccessException e) {
throw new RuntimeException("Handler isn't not accessible for protocol: " + protocol);
}
}
private CloseableJarHandler closeableJarHandler = new CloseableJarHandler();
private CloseableJarHandlerFactory() {
// Force access through the public static functions.
}
@Override
public URLStreamHandler createURLStreamHandler(String protocol) {
if (protocol.equals("jar")) {
// Override the url stream handler for Jar files.
return closeableJarHandler;
} else {
// Regular url stream handling for other protocols.
return createHandlerForProtocol(protocol);
}
}
}