jdk/src/java.base/share/classes/jdk/internal/loader/ClassLoaders.java - platform/libcore - Git at Google

 /*
  * Copyright (c) 2015, 2017, 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.File;
 import java.io.IOException;
 import java.net.URL;
 import java.nio.file.InvalidPathException;
 import java.nio.file.Paths;
 import java.security.CodeSource;
 import java.security.PermissionCollection;
 import java.util.jar.Manifest;

 import jdk.internal.misc.JavaLangAccess;
 import jdk.internal.misc.SharedSecrets;
 import jdk.internal.misc.VM;


 /**
  * Creates and provides access to the built-in platform and application class
  * loaders. It also creates the class loader that is used to locate resources
  * in modules defined to the boot class loader.
  */

 public class ClassLoaders {

     private ClassLoaders() { }

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

     // the built-in class loaders
     private static final BootClassLoader BOOT_LOADER;
     private static final PlatformClassLoader PLATFORM_LOADER;
     private static final AppClassLoader APP_LOADER;

     /**
      * Creates the built-in class loaders
      */
     static {

         // -Xbootclasspth/a or -javaagent Boot-Class-Path
         URLClassPath bcp = null;
         String s = VM.getSavedProperty("jdk.boot.class.path.append");
         if (s != null && s.length() > 0)
             bcp = toURLClassPath(s);

         // we have a class path if -cp is specified or -m is not specified.
         // If neither is specified then default to -cp <working directory>
         // If -cp is not specified and -m is specified, the value of
         // java.class.path is an empty string, then no class path.
         URLClassPath ucp = new URLClassPath(new URL[0]);
         String mainMid = System.getProperty("jdk.module.main");
         String cp = System.getProperty("java.class.path");
         if (cp == null)
             cp = "";
         if (mainMid == null || cp.length() > 0)
             addClassPathToUCP(cp, ucp);

         // create the class loaders
         BOOT_LOADER = new BootClassLoader(bcp);
         PLATFORM_LOADER = new PlatformClassLoader(BOOT_LOADER);
         APP_LOADER = new AppClassLoader(PLATFORM_LOADER, ucp);
     }

     /**
      * Returns the class loader that is used to find resources in modules
      * defined to the boot class loader.
      *
      * @apiNote This method is not public, it should instead be used via
      * the BootLoader class that provides a restricted API to this class
      * loader.
      */
     static BuiltinClassLoader bootLoader() {
         return BOOT_LOADER;
     }

     /**
      * Returns the platform class loader.
      */
     public static ClassLoader platformClassLoader() {
         return PLATFORM_LOADER;
     }

     /**
      * Returns the application class loader.
      */
     public static ClassLoader appClassLoader() {
         return APP_LOADER;
     }

     /**
      * The class loader that is used to find resources in modules defined to
      * the boot class loader. It is not used for class loading.
      */
     private static class BootClassLoader extends BuiltinClassLoader {
         BootClassLoader(URLClassPath bcp) {
             super(null, null, bcp);
         }

         @Override
         protected Class<?> loadClassOrNull(String cn) {
             return JLA.findBootstrapClassOrNull(this, cn);
         }
     };

     /**
      * The platform class loader, a unique type to make it easier to distinguish
      * from the application class loader.
      */
     private static class PlatformClassLoader extends BuiltinClassLoader {
         static {
             if (!ClassLoader.registerAsParallelCapable())
                 throw new InternalError();
         }

         PlatformClassLoader(BootClassLoader parent) {
             super("platform", parent, null);
         }

         /**
          * Called by the VM to support define package for AppCDS.
          *
          * Shared classes are returned in ClassLoader::findLoadedClass
          * that bypass the defineClass call.
          */
         private Package definePackage(String pn, Module module) {
             return JLA.definePackage(this, pn, module);
         }
     }

     /**
      * The application class loader that is a {@code BuiltinClassLoader} with
      * customizations to be compatible with long standing behavior.
      */
     private static class AppClassLoader extends BuiltinClassLoader {
         static {
             if (!ClassLoader.registerAsParallelCapable())
                 throw new InternalError();
         }

         final URLClassPath ucp;

         AppClassLoader(PlatformClassLoader parent, URLClassPath ucp) {
             super("app", parent, ucp);
             this.ucp = ucp;
         }

         @Override
         protected Class<?> loadClass(String cn, boolean resolve)
             throws ClassNotFoundException
         {
             // for compatibility reasons, say where restricted package list has
             // been updated to list API packages in the unnamed module.
             SecurityManager sm = System.getSecurityManager();
             if (sm != null) {
                 int i = cn.lastIndexOf('.');
                 if (i != -1) {
                     sm.checkPackageAccess(cn.substring(0, i));
                 }
             }

             return super.loadClass(cn, resolve);
         }

         @Override
         protected PermissionCollection getPermissions(CodeSource cs) {
             PermissionCollection perms = super.getPermissions(cs);
             perms.add(new RuntimePermission("exitVM"));
             return perms;
         }

         /**
          * Called by the VM to support dynamic additions to the class path
          *
          * @see java.lang.instrument.Instrumentation#appendToSystemClassLoaderSearch
          */
         void appendToClassPathForInstrumentation(String path) {
             addClassPathToUCP(path, ucp);
         }

         /**
          * Called by the VM to support define package for AppCDS
          *
          * Shared classes are returned in ClassLoader::findLoadedClass
          * that bypass the defineClass call.
          */
         private Package definePackage(String pn, Module module) {
             return JLA.definePackage(this, pn, module);
         }

         /**
          * Called by the VM to support define package for AppCDS
          */
         protected Package defineOrCheckPackage(String pn, Manifest man, URL url) {
             return super.defineOrCheckPackage(pn, man, url);
         }
     }

     /**
      * Returns a {@code URLClassPath} of file URLs to each of the elements in
      * the given class path.
      */
     private static URLClassPath toURLClassPath(String cp) {
         URLClassPath ucp = new URLClassPath(new URL[0]);
         addClassPathToUCP(cp, ucp);
         return ucp;
     }

     /**
      * Converts the elements in the given class path to file URLs and adds
      * them to the given URLClassPath.
      */
     private static void addClassPathToUCP(String cp, URLClassPath ucp) {
         int off = 0;
         int next;
         while ((next = cp.indexOf(File.pathSeparator, off)) != -1) {
             URL url = toFileURL(cp.substring(off, next));
             if (url != null)
                 ucp.addURL(url);
             off = next + 1;
         }

         // remaining
         URL url = toFileURL(cp.substring(off));
         if (url != null)
             ucp.addURL(url);
     }

     /**
      * Attempts to convert the given string to a file URL.
      *
      * @apiNote This is called by the VM
      */
     private static URL toFileURL(String s) {
         try {
             // Use an intermediate File object to construct a URI/URL without
             // authority component as URLClassPath can't handle URLs with a UNC
             // server name in the authority component.
             return Paths.get(s).toRealPath().toFile().toURI().toURL();
         } catch (InvalidPathException | IOException ignore) {
             // malformed path string or class path element does not exist
             return null;
         }
     }

 }
	/*
	* Copyright (c) 2015, 2017, 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.File;
	import java.io.IOException;
	import java.net.URL;
	import java.nio.file.InvalidPathException;
	import java.nio.file.Paths;
	import java.security.CodeSource;
	import java.security.PermissionCollection;
	import java.util.jar.Manifest;

	import jdk.internal.misc.JavaLangAccess;
	import jdk.internal.misc.SharedSecrets;
	import jdk.internal.misc.VM;


	/**
	* Creates and provides access to the built-in platform and application class
	* loaders. It also creates the class loader that is used to locate resources
	* in modules defined to the boot class loader.
	*/

	public class ClassLoaders {

	private ClassLoaders() { }

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

	// the built-in class loaders
	private static final BootClassLoader BOOT_LOADER;
	private static final PlatformClassLoader PLATFORM_LOADER;
	private static final AppClassLoader APP_LOADER;

	/**
	* Creates the built-in class loaders
	*/
	static {

	// -Xbootclasspth/a or -javaagent Boot-Class-Path
	URLClassPath bcp = null;
	String s = VM.getSavedProperty("jdk.boot.class.path.append");
	if (s != null && s.length() > 0)
	bcp = toURLClassPath(s);

	// we have a class path if -cp is specified or -m is not specified.
	// If neither is specified then default to -cp <working directory>
	// If -cp is not specified and -m is specified, the value of
	// java.class.path is an empty string, then no class path.
	URLClassPath ucp = new URLClassPath(new URL[0]);
	String mainMid = System.getProperty("jdk.module.main");
	String cp = System.getProperty("java.class.path");
	if (cp == null)
	cp = "";
	if (mainMid == null \|\| cp.length() > 0)
	addClassPathToUCP(cp, ucp);

	// create the class loaders
	BOOT_LOADER = new BootClassLoader(bcp);
	PLATFORM_LOADER = new PlatformClassLoader(BOOT_LOADER);
	APP_LOADER = new AppClassLoader(PLATFORM_LOADER, ucp);
	}

	/**
	* Returns the class loader that is used to find resources in modules
	* defined to the boot class loader.
	*
	* @apiNote This method is not public, it should instead be used via
	* the BootLoader class that provides a restricted API to this class
	* loader.
	*/
	static BuiltinClassLoader bootLoader() {
	return BOOT_LOADER;
	}

	/**
	* Returns the platform class loader.
	*/
	public static ClassLoader platformClassLoader() {
	return PLATFORM_LOADER;
	}

	/**
	* Returns the application class loader.
	*/
	public static ClassLoader appClassLoader() {
	return APP_LOADER;
	}

	/**
	* The class loader that is used to find resources in modules defined to
	* the boot class loader. It is not used for class loading.
	*/
	private static class BootClassLoader extends BuiltinClassLoader {
	BootClassLoader(URLClassPath bcp) {
	super(null, null, bcp);
	}

	@Override
	protected Class<?> loadClassOrNull(String cn) {
	return JLA.findBootstrapClassOrNull(this, cn);
	}
	};

	/**
	* The platform class loader, a unique type to make it easier to distinguish
	* from the application class loader.
	*/
	private static class PlatformClassLoader extends BuiltinClassLoader {
	static {
	if (!ClassLoader.registerAsParallelCapable())
	throw new InternalError();
	}

	PlatformClassLoader(BootClassLoader parent) {
	super("platform", parent, null);
	}

	/**
	* Called by the VM to support define package for AppCDS.
	*
	* Shared classes are returned in ClassLoader::findLoadedClass
	* that bypass the defineClass call.
	*/
	private Package definePackage(String pn, Module module) {
	return JLA.definePackage(this, pn, module);
	}
	}

	/**
	* The application class loader that is a {@code BuiltinClassLoader} with
	* customizations to be compatible with long standing behavior.
	*/
	private static class AppClassLoader extends BuiltinClassLoader {
	static {
	if (!ClassLoader.registerAsParallelCapable())
	throw new InternalError();
	}

	final URLClassPath ucp;

	AppClassLoader(PlatformClassLoader parent, URLClassPath ucp) {
	super("app", parent, ucp);
	this.ucp = ucp;
	}

	@Override
	protected Class<?> loadClass(String cn, boolean resolve)
	throws ClassNotFoundException
	{
	// for compatibility reasons, say where restricted package list has
	// been updated to list API packages in the unnamed module.
	SecurityManager sm = System.getSecurityManager();
	if (sm != null) {
	int i = cn.lastIndexOf('.');
	if (i != -1) {
	sm.checkPackageAccess(cn.substring(0, i));
	}
	}

	return super.loadClass(cn, resolve);
	}

	@Override
	protected PermissionCollection getPermissions(CodeSource cs) {
	PermissionCollection perms = super.getPermissions(cs);
	perms.add(new RuntimePermission("exitVM"));
	return perms;
	}

	/**
	* Called by the VM to support dynamic additions to the class path
	*
	* @see java.lang.instrument.Instrumentation#appendToSystemClassLoaderSearch
	*/
	void appendToClassPathForInstrumentation(String path) {
	addClassPathToUCP(path, ucp);
	}

	/**
	* Called by the VM to support define package for AppCDS
	*
	* Shared classes are returned in ClassLoader::findLoadedClass
	* that bypass the defineClass call.
	*/
	private Package definePackage(String pn, Module module) {
	return JLA.definePackage(this, pn, module);
	}

	/**
	* Called by the VM to support define package for AppCDS
	*/
	protected Package defineOrCheckPackage(String pn, Manifest man, URL url) {
	return super.defineOrCheckPackage(pn, man, url);
	}
	}

	/**
	* Returns a {@code URLClassPath} of file URLs to each of the elements in
	* the given class path.
	*/
	private static URLClassPath toURLClassPath(String cp) {
	URLClassPath ucp = new URLClassPath(new URL[0]);
	addClassPathToUCP(cp, ucp);
	return ucp;
	}

	/**
	* Converts the elements in the given class path to file URLs and adds
	* them to the given URLClassPath.
	*/
	private static void addClassPathToUCP(String cp, URLClassPath ucp) {
	int off = 0;
	int next;
	while ((next = cp.indexOf(File.pathSeparator, off)) != -1) {
	URL url = toFileURL(cp.substring(off, next));
	if (url != null)
	ucp.addURL(url);
	off = next + 1;
	}

	// remaining
	URL url = toFileURL(cp.substring(off));
	if (url != null)
	ucp.addURL(url);
	}

	/**
	* Attempts to convert the given string to a file URL.
	*
	* @apiNote This is called by the VM
	*/
	private static URL toFileURL(String s) {
	try {
	// Use an intermediate File object to construct a URI/URL without
	// authority component as URLClassPath can't handle URLs with a UNC
	// server name in the authority component.
	return Paths.get(s).toRealPath().toFile().toURI().toURL();
	} catch (InvalidPathException \| IOException ignore) {
	// malformed path string or class path element does not exist
	return null;
	}
	}

	}