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	/*
	* Copyright (c) 2015, 2021, 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.internal.loader;

	import java.io.IOException;
	import java.io.InputStream;
	import java.lang.module.ModuleReference;
	import java.net.MalformedURLException;
	import java.net.URI;
	import java.net.URL;
	import java.nio.file.Files;
	import java.nio.file.Path;
	import java.security.AccessController;
	import java.security.PrivilegedAction;
	import java.util.Arrays;
	import java.util.Enumeration;
	import java.util.concurrent.ConcurrentHashMap;
	import java.util.jar.JarInputStream;
	import java.util.jar.Manifest;
	import java.util.stream.Stream;

	import jdk.internal.access.JavaLangAccess;
	import jdk.internal.access.SharedSecrets;
	import jdk.internal.module.Modules;
	import jdk.internal.module.ServicesCatalog;
	import jdk.internal.util.StaticProperty;

	/**
	* Find resources and packages in modules defined to the boot class loader or
	* resources and packages on the "boot class path" specified via -Xbootclasspath/a.
	*/

	public class BootLoader {
	private BootLoader() { }

	private static final JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();

	// The unnamed module for the boot loader
	private static final Module UNNAMED_MODULE;
	private static final String JAVA_HOME = StaticProperty.javaHome();

	static {
	JavaLangAccess jla = SharedSecrets.getJavaLangAccess();
	UNNAMED_MODULE = jla.defineUnnamedModule(null);
	jla.addEnableNativeAccess(UNNAMED_MODULE);
	setBootLoaderUnnamedModule0(UNNAMED_MODULE);
	}

	// ClassLoaderValue map for the boot class loader
	private static final ConcurrentHashMap<?, ?> CLASS_LOADER_VALUE_MAP
	= new ConcurrentHashMap<>();

	// native libraries loaded by the boot class loader
	private static final NativeLibraries NATIVE_LIBS
	= NativeLibraries.jniNativeLibraries(null);

	/**
	* Returns the unnamed module for the boot loader.
	*/
	public static Module getUnnamedModule() {
	return UNNAMED_MODULE;
	}

	/**
	* Returns the ServiceCatalog for modules defined to the boot class loader.
	*/
	public static ServicesCatalog getServicesCatalog() {
	return ServicesCatalog.getServicesCatalog(ClassLoaders.bootLoader());
	}

	/**
	* Returns the ClassLoaderValue map for the boot class loader.
	*/
	public static ConcurrentHashMap<?, ?> getClassLoaderValueMap() {
	return CLASS_LOADER_VALUE_MAP;
	}

	/**
	* Returns NativeLibraries for the boot class loader.
	*/
	public static NativeLibraries getNativeLibraries() {
	return NATIVE_LIBS;
	}

	/**
	* Returns {@code true} if there is a class path associated with the
	* BootLoader.
	*/
	public static boolean hasClassPath() {
	return ClassLoaders.bootLoader().hasClassPath();
	}

	/**
	* Registers a module with this class loader so that its classes
	* (and resources) become visible via this class loader.
	*/
	public static void loadModule(ModuleReference mref) {
	ClassLoaders.bootLoader().loadModule(mref);
	}

	/**
	* Loads the Class object with the given name defined to the boot loader.
	*/
	public static Class<?> loadClassOrNull(String name) {
	return JLA.findBootstrapClassOrNull(name);
	}

	/**
	* Loads the Class object with the given name in the given module
	* defined to the boot loader. Returns {@code null} if not found.
	*/
	public static Class<?> loadClass(Module module, String name) {
	Class<?> c = loadClassOrNull(name);
	if (c != null && c.getModule() == module) {
	return c;
	} else {
	return null;
	}
	}

	/**
	* Loads a native library from the system library path.
	*/
	@SuppressWarnings("removal")
	public static void loadLibrary(String name) {
	if (System.getSecurityManager() == null) {
	BootLoader.getNativeLibraries().loadLibrary(name);
	} else {
	AccessController.doPrivileged(new java.security.PrivilegedAction<>() {
	public Void run() {
	BootLoader.getNativeLibraries().loadLibrary(name);
	return null;
	}
	});
	}
	}

	/**
	* Returns a URL to a resource in a module defined to the boot loader.
	*/
	public static URL findResource(String mn, String name) throws IOException {
	return ClassLoaders.bootLoader().findResource(mn, name);
	}

	/**
	* Returns an input stream to a resource in a module defined to the
	* boot loader.
	*/
	public static InputStream findResourceAsStream(String mn, String name)
	throws IOException
	{
	return ClassLoaders.bootLoader().findResourceAsStream(mn, name);
	}

	/**
	* Returns the URL to the given resource in any of the modules
	* defined to the boot loader and the boot class path.
	*/
	public static URL findResource(String name) {
	return ClassLoaders.bootLoader().findResource(name);
	}

	/**
	* Returns an Iterator to iterate over the resources of the given name
	* in any of the modules defined to the boot loader.
	*/
	public static Enumeration<URL> findResources(String name) throws IOException {
	return ClassLoaders.bootLoader().findResources(name);
	}

	/**
	* Define a package for the given class to the boot loader, if not already
	* defined.
	*/
	public static Package definePackage(Class<?> c) {
	return getDefinedPackage(c.getPackageName());
	}

	/**
	* Returns the Package of the given name defined to the boot loader or null
	* if the package has not been defined.
	*/
	public static Package getDefinedPackage(String pn) {
	Package pkg = ClassLoaders.bootLoader().getDefinedPackage(pn);
	if (pkg == null) {
	String location = getSystemPackageLocation(pn.replace('.', '/'));
	if (location != null) {
	pkg = PackageHelper.definePackage(pn.intern(), location);
	}
	}
	return pkg;
	}

	/**
	* Returns a stream of the packages defined to the boot loader.
	*/
	public static Stream<Package> packages() {
	return Arrays.stream(getSystemPackageNames())
	.map(name -> getDefinedPackage(name.replace('/', '.')));
	}

	/**
	* Helper class to define {@code Package} objects for packages in modules
	* defined to the boot loader.
	*/
	static class PackageHelper {
	private static final JavaLangAccess JLA = SharedSecrets.getJavaLangAccess();

	/**
	* Define the {@code Package} with the given name. The specified
	* location is a jrt URL to a named module in the run-time image,
	* a file URL to a module in an exploded run-time image, or a file
	* path to an entry on the boot class path (java agent Boot-Class-Path
	* or -Xbootclasspath/a.
	*
	* <p> If the given location is a JAR file containing a manifest,
	* the defined Package contains the versioning information from
	* the manifest, if present.
	*
	* @param name package name
	* @param location location where the package is (jrt URL or file URL
	* for a named module in the run-time or exploded image;
	* a file path for a package from -Xbootclasspath/a)
	*/
	static Package definePackage(String name, String location) {
	Module module = findModule(location);
	if (module != null) {
	// named module from runtime image or exploded module
	if (name.isEmpty())
	throw new InternalError("empty package in " + location);
	return JLA.definePackage(ClassLoaders.bootLoader(), name, module);
	}

	// package in unnamed module (-Xbootclasspath/a)
	URL url = toFileURL(location);
	Manifest man = url != null ? getManifest(location) : null;

	return ClassLoaders.bootLoader().defineOrCheckPackage(name, man, url);
	}

	/**
	* Finds the module at the given location defined to the boot loader.
	* The module is either in runtime image or exploded image.
	* Otherwise this method returns null.
	*/
	private static Module findModule(String location) {
	String mn = null;
	if (location.startsWith("jrt:/")) {
	// named module in runtime image ("jrt:/".length() == 5)
	mn = location.substring(5, location.length());
	} else if (location.startsWith("file:/")) {
	// named module in exploded image
	Path path = Path.of(URI.create(location));
	Path modulesDir = Path.of(JAVA_HOME, "modules");
	if (path.startsWith(modulesDir)) {
	mn = path.getFileName().toString();
	}
	}

	// return the Module object for the module name. The Module may
	// in the boot layer or a child layer for the case that the module
	// is loaded into a running VM
	if (mn != null) {
	String name = mn;
	return Modules.findLoadedModule(mn)
	.orElseThrow(() -> new InternalError(name + " not loaded"));
	} else {
	return null;
	}
	}

	/**
	* Returns URL if the given location is a regular file path.
	*/
	@SuppressWarnings("removal")
	private static URL toFileURL(String location) {
	return AccessController.doPrivileged(new PrivilegedAction<>() {
	public URL run() {
	Path path = Path.of(location);
	if (Files.isRegularFile(path)) {
	try {
	return path.toUri().toURL();
	} catch (MalformedURLException e) {}
	}
	return null;
	}
	});
	}

	/**
	* Returns the Manifest if the given location is a JAR file
	* containing a manifest.
	*/
	@SuppressWarnings("removal")
	private static Manifest getManifest(String location) {
	return AccessController.doPrivileged(new PrivilegedAction<>() {
	public Manifest run() {
	Path jar = Path.of(location);
	try (InputStream in = Files.newInputStream(jar);
	JarInputStream jis = new JarInputStream(in, false)) {
	return jis.getManifest();
	} catch (IOException e) {
	return null;
	}
	}
	});
	}
	}

	/**
	* Returns an array of the binary name of the packages defined by
	* the boot loader, in VM internal form (forward slashes instead of dot).
	*/
	private static native String[] getSystemPackageNames();

	/**
	* Returns the location of the package of the given name, if
	* defined by the boot loader; otherwise {@code null} is returned.
	*
	* The location may be a module from the runtime image or exploded image,
	* or from the boot class append path (i.e. -Xbootclasspath/a or
	* BOOT-CLASS-PATH attribute specified in java agent).
	*/
	private static native String getSystemPackageLocation(String name);
	private static native void setBootLoaderUnnamedModule0(Module module);
	}

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