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3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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).
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17  * You should have received a copy of the GNU General Public License version
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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 abstract class SystemImage {
51 
findNode(String path)52     abstract Node findNode(String path) throws IOException;
getResource(Node node)53     abstract byte[] getResource(Node node) throws IOException;
close()54     abstract void close() throws IOException;
55 
open()56     static SystemImage open() throws IOException {
57         if (modulesImageExists) {
58             // open a .jimage and build directory structure
59             final ImageReader image = ImageReader.open(moduleImageFile);
60             image.getRootDirectory();
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     final static Path moduleImageFile;
84     // "modules" jimage exists or not?
85     final static 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 }
131