1 /* 2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 package jdk.internal.jrtfs; 26 27 import java.net.URISyntaxException; 28 import java.net.URL; 29 import java.nio.file.Files; 30 import java.nio.file.FileSystem; 31 import java.nio.file.FileSystems; 32 import java.nio.file.Path; 33 import java.nio.file.Paths; 34 import java.security.AccessController; 35 import java.security.CodeSource; 36 import java.security.PrivilegedAction; 37 38 /** 39 * @implNote This class needs to maintain JDK 8 source compatibility. 40 * 41 * It is used internally in the JDK to implement jimage/jrtfs access, 42 * but also compiled and delivered as part of the jrtfs.jar to support access 43 * to the jimage file provided by the shipped JDK by tools running on JDK 8. 44 */ 45 final class SystemImages { 46 private SystemImages() {} 47 48 49 static final String RUNTIME_HOME; 50 // "modules" jimage file Path 51 private static final Path moduleImageFile; 52 // "modules" jimage exists or not? 53 private static final boolean modulesImageExists; 54 // <JAVA_HOME>/modules directory Path 55 private static final Path explodedModulesDir; 56 57 static { 58 PrivilegedAction<String> pa = SystemImages::findHome; 59 RUNTIME_HOME = AccessController.doPrivileged(pa); 60 61 FileSystem fs = FileSystems.getDefault(); 62 moduleImageFile = fs.getPath(RUNTIME_HOME, "lib", "modules"); 63 explodedModulesDir = fs.getPath(RUNTIME_HOME, "modules"); 64 65 modulesImageExists = AccessController.doPrivileged( 66 new PrivilegedAction<Boolean>() { 67 @Override 68 public Boolean run() { 69 return Files.isRegularFile(moduleImageFile); 70 } 71 }); 72 } 73 74 static boolean hasModulesImage() { 75 return modulesImageExists; 76 } 77 78 static Path moduleImageFile() { 79 return moduleImageFile; 80 } 81 82 static Path explodedModulesDir() { 83 return explodedModulesDir; 84 } 85 86 /** 87 * Returns the appropriate JDK home for this usage of the FileSystemProvider. 88 * When the CodeSource is null (null loader) then jrt:/ is the current runtime, 89 * otherwise the JDK home is located relative to jrt-fs.jar. 90 */ 91 private static String findHome() { 92 CodeSource cs = SystemImages.class.getProtectionDomain().getCodeSource(); 93 if (cs == null) 94 return System.getProperty("java.home"); 95 96 // assume loaded from $TARGETJDK/jrt-fs.jar 97 URL url = cs.getLocation(); 98 if (!url.getProtocol().equalsIgnoreCase("file")) 99 throw new RuntimeException(url + " loaded in unexpected way"); 100 try { 101 return Paths.get(url.toURI()).getParent().toString(); 102 } catch (URISyntaxException e) { 103 throw new InternalError(e); 104 } 105 } 106 }