| /* |
| * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package jdk.dynalink.linker; |
| |
| import java.security.Permission; |
| import java.util.List; |
| import java.util.ServiceLoader; |
| import java.util.function.Supplier; |
| import jdk.dynalink.DynamicLinkerFactory; |
| |
| /** |
| * A class acting as a supplier of guarding dynamic linkers that can be |
| * automatically loaded by other language runtimes. Language runtimes wishing |
| * to export their own linkers should subclass this class and implement the |
| * {@link #get()} method to return a list of exported linkers and declare the |
| * subclass in |
| * {@code /META-INF/services/jdk.dynalink.linker.GuardingDynamicLinkerExporter} |
| * resource of their distribution (typically, JAR file) so that dynamic linker |
| * factories can discover them using the {@link ServiceLoader} mechanism. Note |
| * that instantiating this class is tied to a security check for the |
| * {@code RuntimePermission("dynalink.exportLinkersAutomatically")} when a |
| * security manager is present, to ensure that only trusted runtimes can |
| * automatically export their linkers into other runtimes. |
| * @see DynamicLinkerFactory#setClassLoader(ClassLoader) |
| */ |
| public abstract class GuardingDynamicLinkerExporter implements Supplier<List<GuardingDynamicLinker>> { |
| /** |
| * The name of the runtime permission for creating instances of this class. |
| * Granting this permission to a language runtime allows it to export its |
| * linkers for automatic loading into other language runtimes. |
| */ |
| public static final String AUTOLOAD_PERMISSION_NAME = "dynalink.exportLinkersAutomatically"; |
| |
| private static final Permission AUTOLOAD_PERMISSION = new RuntimePermission(AUTOLOAD_PERMISSION_NAME); |
| |
| /** |
| * Creates a new linker exporter. If there is a security manager installed |
| * checks for the |
| * {@code RuntimePermission("dynalink.exportLinkersAutomatically")} runtime |
| * permission. This ensures only language runtimes granted this permission |
| * will be allowed to export their linkers for automatic loading. |
| * @throws SecurityException if the necessary runtime permission is not |
| * granted. |
| */ |
| protected GuardingDynamicLinkerExporter() { |
| final SecurityManager sm = System.getSecurityManager(); |
| if (sm != null) { |
| sm.checkPermission(AUTOLOAD_PERMISSION); |
| } |
| } |
| } |