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	/*
	* Copyright (c) 1997, 2015, 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 java.security;

	import java.util.Map;
	import java.util.Objects;
	import java.util.concurrent.ConcurrentHashMap;
	import java.util.function.Function;

	import sun.security.util.Debug;

	/**
	* This class extends ClassLoader with additional support for defining
	* classes with an associated code source and permissions which are
	* retrieved by the system policy by default.
	*
	* @author Li Gong
	* @author Roland Schemers
	* @since 1.2
	*/
	public class SecureClassLoader extends ClassLoader {
	/*
	* If initialization succeed this is set to true and security checks will
	* succeed. Otherwise the object is not initialized and the object is
	* useless.
	*/
	private final boolean initialized;

	/*
	* Map that maps the CodeSource to a ProtectionDomain. The key is a
	* CodeSourceKey class that uses a String instead of a URL to avoid
	* potential expensive name service lookups. This does mean that URLs that
	* are equivalent after nameservice lookup will be placed in separate
	* ProtectionDomains; however during policy enforcement these URLs will be
	* canonicalized and resolved resulting in a consistent set of granted
	* permissions.
	*/
	private final Map<CodeSourceKey, ProtectionDomain> pdcache
	= new ConcurrentHashMap<>(11);

	static {
	ClassLoader.registerAsParallelCapable();
	}

	/**
	* Creates a new SecureClassLoader using the specified parent
	* class loader for delegation.
	*
	* <p>If there is a security manager, this method first
	* calls the security manager's {@code checkCreateClassLoader}
	* method to ensure creation of a class loader is allowed.
	*
	* @param parent the parent ClassLoader
	* @exception SecurityException if a security manager exists and its
	* {@code checkCreateClassLoader} method doesn't allow
	* creation of a class loader.
	* @see SecurityManager#checkCreateClassLoader
	*/
	protected SecureClassLoader(ClassLoader parent) {
	super(parent);
	// this is to make the stack depth consistent with 1.1
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkCreateClassLoader();
	}
	initialized = true;
	}

	/**
	* Creates a new SecureClassLoader using the default parent class
	* loader for delegation.
	*
	* <p>If there is a security manager, this method first
	* calls the security manager's {@code checkCreateClassLoader}
	* method to ensure creation of a class loader is allowed.
	*
	* @exception SecurityException if a security manager exists and its
	* {@code checkCreateClassLoader} method doesn't allow
	* creation of a class loader.
	* @see SecurityManager#checkCreateClassLoader
	*/
	protected SecureClassLoader() {
	super();
	// this is to make the stack depth consistent with 1.1
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkCreateClassLoader();
	}
	initialized = true;
	}

	/**
	* Creates a new {@code SecureClassLoader} of the specified name and
	* using the specified parent class loader for delegation.
	*
	* @param name class loader name; or {@code null} if not named
	* @param parent the parent class loader
	*
	* @throws IllegalArgumentException if the given name is empty.
	*
	* @throws SecurityException if a security manager exists and its
	* {@link SecurityManager#checkCreateClassLoader()} method
	* doesn't allow creation of a class loader.
	*
	* @since 9
	* @spec JPMS
	*/
	protected SecureClassLoader(String name, ClassLoader parent) {
	super(name, parent);
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	security.checkCreateClassLoader();
	}
	initialized = true;
	}

	/**
	* Converts an array of bytes into an instance of class Class,
	* with an optional CodeSource. Before the
	* class can be used it must be resolved.
	* <p>
	* If a non-null CodeSource is supplied a ProtectionDomain is
	* constructed and associated with the class being defined.
	*
	* @param name the expected name of the class, or {@code null}
	* if not known, using '.' and not '/' as the separator
	* and without a trailing ".class" suffix.
	* @param b the bytes that make up the class data. The bytes in
	* positions {@code off} through {@code off+len-1}
	* should have the format of a valid class file as defined by
	* <cite>The Java™ Virtual Machine Specification</cite>.
	* @param off the start offset in {@code b} of the class data
	* @param len the length of the class data
	* @param cs the associated CodeSource, or {@code null} if none
	* @return the {@code Class} object created from the data,
	* and optional CodeSource.
	* @exception ClassFormatError if the data did not contain a valid class
	* @exception IndexOutOfBoundsException if either {@code off} or
	* {@code len} is negative, or if
	* {@code off+len} is greater than {@code b.length}.
	*
	* @exception SecurityException if an attempt is made to add this class
	* to a package that contains classes that were signed by
	* a different set of certificates than this class, or if
	* the class name begins with "java.".
	*/
	protected final Class<?> defineClass(String name,
	byte[] b, int off, int len,
	CodeSource cs)
	{
	return defineClass(name, b, off, len, getProtectionDomain(cs));
	}

	/**
	* Converts a {@link java.nio.ByteBuffer ByteBuffer}
	* into an instance of class {@code Class}, with an optional CodeSource.
	* Before the class can be used it must be resolved.
	* <p>
	* If a non-null CodeSource is supplied a ProtectionDomain is
	* constructed and associated with the class being defined.
	*
	* @param name the expected name of the class, or {@code null}
	* if not known, using '.' and not '/' as the separator
	* and without a trailing ".class" suffix.
	* @param b the bytes that make up the class data. The bytes from positions
	* {@code b.position()} through {@code b.position() + b.limit() -1}
	* should have the format of a valid class file as defined by
	* <cite>The Java™ Virtual Machine Specification</cite>.
	* @param cs the associated CodeSource, or {@code null} if none
	* @return the {@code Class} object created from the data,
	* and optional CodeSource.
	* @exception ClassFormatError if the data did not contain a valid class
	* @exception SecurityException if an attempt is made to add this class
	* to a package that contains classes that were signed by
	* a different set of certificates than this class, or if
	* the class name begins with "java.".
	*
	* @since 1.5
	*/
	protected final Class<?> defineClass(String name, java.nio.ByteBuffer b,
	CodeSource cs)
	{
	return defineClass(name, b, getProtectionDomain(cs));
	}

	/**
	* Returns the permissions for the given CodeSource object.
	* <p>
	* This method is invoked by the defineClass method which takes
	* a CodeSource as an argument when it is constructing the
	* ProtectionDomain for the class being defined.
	*
	* @param codesource the codesource.
	*
	* @return the permissions granted to the codesource.
	*
	*/
	protected PermissionCollection getPermissions(CodeSource codesource)
	{
	check();
	return new Permissions(); // ProtectionDomain defers the binding
	}

	/*
	* holder class for the static field "debug" to delay its initialization
	*/
	private static class DebugHolder {
	private static final Debug debug = Debug.getInstance("scl");
	}

	/*
	* Returned cached ProtectionDomain for the specified CodeSource.
	*/
	private ProtectionDomain getProtectionDomain(CodeSource cs) {
	if (cs == null) {
	return null;
	}

	// Use a CodeSourceKey object key. It should behave in the
	// same manner as the CodeSource when compared for equality except
	// that no nameservice lookup is done on the hostname (String comparison
	// only), and the fragment is not considered.
	CodeSourceKey key = new CodeSourceKey(cs);
	return pdcache.computeIfAbsent(key, new Function<>() {
	@Override
	public ProtectionDomain apply(CodeSourceKey key /* not used */) {
	PermissionCollection perms
	= SecureClassLoader.this.getPermissions(cs);
	ProtectionDomain pd = new ProtectionDomain(
	cs, perms, SecureClassLoader.this, null);
	if (DebugHolder.debug != null) {
	DebugHolder.debug.println(" getPermissions " + pd);
	DebugHolder.debug.println("");
	}
	return pd;
	}
	});
	}

	/*
	* Check to make sure the class loader has been initialized.
	*/
	private void check() {
	if (!initialized) {
	throw new SecurityException("ClassLoader object not initialized");
	}
	}

	private static class CodeSourceKey {
	private final CodeSource cs;

	CodeSourceKey(CodeSource cs) {
	this.cs = cs;
	}

	@Override
	public int hashCode() {
	String locationNoFrag = cs.getLocationNoFragString();
	return locationNoFrag != null ? locationNoFrag.hashCode() : 0;
	}

	@Override
	public boolean equals(Object obj) {
	if (obj == this) {
	return true;
	}

	if (!(obj instanceof CodeSourceKey)) {
	return false;
	}

	CodeSourceKey csk = (CodeSourceKey) obj;

	if (!Objects.equals(cs.getLocationNoFragString(),
	csk.cs.getLocationNoFragString())) {
	return false;
	}

	return cs.matchCerts(csk.cs, true);
	}
	}
	}

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