1 /*
2 * Copyright (c) 2014, 2025, 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.io.IOException;
28 import java.net.URISyntaxException;
29 import java.net.URL;
30 import java.nio.file.Files;
31 import java.nio.file.FileSystem;
32 import java.nio.file.FileSystems;
33 import java.nio.file.FileSystemNotFoundException;
34 import java.nio.file.Path;
35 import java.nio.file.Paths;
36 import java.security.AccessController;
37 import java.security.CodeSource;
38 import java.security.PrivilegedAction;
39
40 import jdk.internal.jimage.ImageReader;
41 import jdk.internal.jimage.ImageReader.Node;
42
43 /**
44 * @implNote This class needs to maintain JDK 8 source compatibility.
45 *
46 * It is used internally in the JDK to implement jimage/jrtfs access,
47 * but also compiled and delivered as part of the jrtfs.jar to support access
48 * to the jimage file provided by the shipped JDK by tools running on JDK 8.
49 */
50 @SuppressWarnings({ "removal", "suppression"} )
51 abstract class SystemImage {
52
53 abstract Node findNode(String path) throws IOException;
54 abstract byte[] getResource(Node node) throws IOException;
55 abstract void close() throws IOException;
56
57 static SystemImage open() throws IOException {
58 if (modulesImageExists) {
59 // open a .jimage and build directory structure
60 final ImageReader image = ImageReader.open(moduleImageFile);
61 return new SystemImage() {
62 @Override
63 Node findNode(String path) throws IOException {
64 return image.findNode(path);
65 }
66 @Override
67 byte[] getResource(Node node) throws IOException {
68 return image.getResource(node);
69 }
70 @Override
71 void close() throws IOException {
72 image.close();
73 }
74 };
75 }
76 if (Files.notExists(explodedModulesDir))
77 throw new FileSystemNotFoundException(explodedModulesDir.toString());
78 return new ExplodedImage(explodedModulesDir);
79 }
80
81 static final String RUNTIME_HOME;
82 // "modules" jimage file Path
83 static final Path moduleImageFile;
84 // "modules" jimage exists or not?
85 static final boolean modulesImageExists;
86 // <JAVA_HOME>/modules directory Path
87 static final Path explodedModulesDir;
88
89 static {
90 PrivilegedAction<String> pa = SystemImage::findHome;
91 RUNTIME_HOME = AccessController.doPrivileged(pa);
92
93 FileSystem fs = FileSystems.getDefault();
94 moduleImageFile = fs.getPath(RUNTIME_HOME, "lib", "modules");
95 explodedModulesDir = fs.getPath(RUNTIME_HOME, "modules");
96
97 modulesImageExists = AccessController.doPrivileged(
98 new PrivilegedAction<Boolean>() {
99 @Override
100 public Boolean run() {
101 return Files.isRegularFile(moduleImageFile);
102 }
103 });
104 }
105
106 /**
107 * Returns the appropriate JDK home for this usage of the FileSystemProvider.
108 * When the CodeSource is null (null loader) then jrt:/ is the current runtime,
109 * otherwise the JDK home is located relative to jrt-fs.jar.
110 */
111 private static String findHome() {
112 CodeSource cs = SystemImage.class.getProtectionDomain().getCodeSource();
113 if (cs == null)
114 return System.getProperty("java.home");
115
116 // assume loaded from $TARGETJDK/lib/jrt-fs.jar
117 URL url = cs.getLocation();
118 if (!url.getProtocol().equalsIgnoreCase("file"))
119 throw new InternalError(url + " loaded in unexpected way");
120 try {
121 Path lib = Paths.get(url.toURI()).getParent();
122 if (!lib.getFileName().toString().equals("lib"))
123 throw new InternalError(url + " unexpected path");
124
125 return lib.getParent().toString();
126 } catch (URISyntaxException e) {
127 throw new InternalError(e);
128 }
129 }
130 }