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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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package jdk.internal.jrtfs;

import java.io.IOException;
import java.net.URISyntaxException;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.FileSystem;
import java.nio.file.FileSystems;
import java.nio.file.FileSystemNotFoundException;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.security.AccessController;
import java.security.CodeSource;
import java.security.PrivilegedAction;

import jdk.internal.jimage.ImageReader;
import jdk.internal.jimage.ImageReader.Node;

Implementation Note:This class needs to maintain JDK 8 source compatibility. It is used internally in the JDK to implement jimage/jrtfs access, but also compiled and delivered as part of the jrtfs.jar to support access to the jimage file provided by the shipped JDK by tools running on JDK 8.
/** * @implNote This class needs to maintain JDK 8 source compatibility. * * It is used internally in the JDK to implement jimage/jrtfs access, * but also compiled and delivered as part of the jrtfs.jar to support access * to the jimage file provided by the shipped JDK by tools running on JDK 8. */
abstract class SystemImage { abstract Node findNode(String path) throws IOException; abstract byte[] getResource(Node node) throws IOException; abstract void close() throws IOException; static SystemImage open() throws IOException { if (modulesImageExists) { // open a .jimage and build directory structure final ImageReader image = ImageReader.open(moduleImageFile); image.getRootDirectory(); return new SystemImage() { @Override Node findNode(String path) throws IOException { return image.findNode(path); } @Override byte[] getResource(Node node) throws IOException { return image.getResource(node); } @Override void close() throws IOException { image.close(); } }; } if (Files.notExists(explodedModulesDir)) throw new FileSystemNotFoundException(explodedModulesDir.toString()); return new ExplodedImage(explodedModulesDir); } static final String RUNTIME_HOME; // "modules" jimage file Path final static Path moduleImageFile; // "modules" jimage exists or not? final static boolean modulesImageExists; // <JAVA_HOME>/modules directory Path static final Path explodedModulesDir; static { PrivilegedAction<String> pa = SystemImage::findHome; RUNTIME_HOME = AccessController.doPrivileged(pa); FileSystem fs = FileSystems.getDefault(); moduleImageFile = fs.getPath(RUNTIME_HOME, "lib", "modules"); explodedModulesDir = fs.getPath(RUNTIME_HOME, "modules"); modulesImageExists = AccessController.doPrivileged( new PrivilegedAction<Boolean>() { @Override public Boolean run() { return Files.isRegularFile(moduleImageFile); } }); }
Returns the appropriate JDK home for this usage of the FileSystemProvider. When the CodeSource is null (null loader) then jrt:/ is the current runtime, otherwise the JDK home is located relative to jrt-fs.jar.
/** * Returns the appropriate JDK home for this usage of the FileSystemProvider. * When the CodeSource is null (null loader) then jrt:/ is the current runtime, * otherwise the JDK home is located relative to jrt-fs.jar. */
private static String findHome() { CodeSource cs = SystemImage.class.getProtectionDomain().getCodeSource(); if (cs == null) return System.getProperty("java.home"); // assume loaded from $TARGETJDK/lib/jrt-fs.jar URL url = cs.getLocation(); if (!url.getProtocol().equalsIgnoreCase("file")) throw new InternalError(url + " loaded in unexpected way"); try { Path lib = Paths.get(url.toURI()).getParent(); if (!lib.getFileName().toString().equals("lib")) throw new InternalError(url + " unexpected path"); return lib.getParent().toString(); } catch (URISyntaxException e) { throw new InternalError(e); } } }