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	/*
	* Copyright (c) 2005, 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 sun.reflect.misc;

	import java.lang.reflect.Member;
	import java.lang.reflect.Method;
	import java.lang.reflect.Modifier;
	import java.lang.reflect.Proxy;
	import jdk.internal.reflect.Reflection;
	import sun.security.util.SecurityConstants;

	public final class ReflectUtil {

	private ReflectUtil() {
	}

	public static Class<?> forName(String name)
	throws ClassNotFoundException {
	checkPackageAccess(name);
	return Class.forName(name);
	}

	/**
	* Ensures that access to a method or field is granted and throws
	* IllegalAccessException if not. This method is not suitable for checking
	* access to constructors.
	*
	* @param currentClass the class performing the access
	* @param memberClass the declaring class of the member being accessed
	* @param target the target object if accessing instance field or method;
	* or null if accessing static field or method or if target
	* object access rights will be checked later
	* @param modifiers the member's access modifiers
	* @throws IllegalAccessException if access to member is denied
	* @implNote Delegates directly to
	* {@link Reflection#ensureMemberAccess(Class, Class, Class, int)}
	* which should be used instead.
	*/
	public static void ensureMemberAccess(Class<?> currentClass,
	Class<?> memberClass,
	Object target,
	int modifiers)
	throws IllegalAccessException
	{
	Reflection.ensureMemberAccess(currentClass,
	memberClass,
	target == null ? null : target.getClass(),
	modifiers);
	}

	/**
	* Does a conservative approximation of member access check. Use this if
	* you don't have an actual 'userland' caller Class/ClassLoader available.
	* This might be more restrictive than a precise member access check where
	* you have a caller, but should never allow a member access that is
	* forbidden.
	*
	* @param m the {@code Member} about to be accessed
	*/
	public static void conservativeCheckMemberAccess(Member m) throws SecurityException{
	@SuppressWarnings("removal")
	final SecurityManager sm = System.getSecurityManager();
	if (sm == null)
	return;

	// Check for package access on the declaring class.
	//
	// In addition, unless the member and the declaring class are both
	// public check for access declared member permissions.
	//
	// This is done regardless of ClassLoader relations between the {@code
	// Member m} and any potential caller.

	final Class<?> declaringClass = m.getDeclaringClass();

	privateCheckPackageAccess(sm, declaringClass);

	if (Modifier.isPublic(m.getModifiers()) &&
	Modifier.isPublic(declaringClass.getModifiers()))
	return;

	// Check for declared member access.
	sm.checkPermission(SecurityConstants.CHECK_MEMBER_ACCESS_PERMISSION);
	}

	/**
	* Checks package access on the given class.
	*
	* If it is a {@link Proxy#isProxyClass(java.lang.Class)} that implements
	* a non-public interface (i.e. may be in a non-restricted package),
	* also check the package access on the proxy interfaces.
	*/
	public static void checkPackageAccess(Class<?> clazz) {
	@SuppressWarnings("removal")
	SecurityManager s = System.getSecurityManager();
	if (s != null) {
	privateCheckPackageAccess(s, clazz);
	}
	}

	/**
	* NOTE: should only be called if a SecurityManager is installed
	*/
	private static void privateCheckPackageAccess(@SuppressWarnings("removal") SecurityManager s, Class<?> clazz) {
	String pkg = clazz.getPackageName();
	if (!pkg.isEmpty()) {
	s.checkPackageAccess(pkg);
	}

	if (isNonPublicProxyClass(clazz)) {
	privateCheckProxyPackageAccess(s, clazz);
	}
	}

	/**
	* Checks package access on the given classname.
	* This method is typically called when the Class instance is not
	* available and the caller attempts to load a class on behalf
	* the true caller (application).
	*/
	public static void checkPackageAccess(String name) {
	@SuppressWarnings("removal")
	SecurityManager s = System.getSecurityManager();
	if (s != null) {
	String cname = name.replace('/', '.');
	if (cname.startsWith("[")) {
	int b = cname.lastIndexOf('[') + 2;
	if (b > 1 && b < cname.length()) {
	cname = cname.substring(b);
	}
	}
	int i = cname.lastIndexOf('.');
	if (i != -1) {
	s.checkPackageAccess(cname.substring(0, i));
	}
	}
	}

	public static boolean isPackageAccessible(Class<?> clazz) {
	try {
	checkPackageAccess(clazz);
	} catch (SecurityException e) {
	return false;
	}
	return true;
	}

	// Returns true if p is an ancestor of cl i.e. class loader 'p' can
	// be found in the cl's delegation chain
	private static boolean isAncestor(ClassLoader p, ClassLoader cl) {
	ClassLoader acl = cl;
	do {
	acl = acl.getParent();
	if (p == acl) {
	return true;
	}
	} while (acl != null);
	return false;
	}

	/**
	* Returns true if package access check is needed for reflective
	* access from a class loader 'from' to classes or members in
	* a class defined by class loader 'to'. This method returns true
	* if 'from' is not the same as or an ancestor of 'to'. All code
	* in a system domain are granted with all permission and so this
	* method returns false if 'from' class loader is a class loader
	* loading system classes. On the other hand, if a class loader
	* attempts to access system domain classes, it requires package
	* access check and this method will return true.
	*/
	public static boolean needsPackageAccessCheck(ClassLoader from, ClassLoader to) {
	if (from == null \|\| from == to)
	return false;

	if (to == null)
	return true;

	return !isAncestor(from, to);
	}

	/**
	* Check package access on the proxy interfaces that the given proxy class
	* implements.
	*
	* @param clazz Proxy class object
	*/
	public static void checkProxyPackageAccess(Class<?> clazz) {
	@SuppressWarnings("removal")
	SecurityManager s = System.getSecurityManager();
	if (s != null) {
	privateCheckProxyPackageAccess(s, clazz);
	}
	}

	/**
	* NOTE: should only be called if a SecurityManager is installed
	*/
	private static void privateCheckProxyPackageAccess(@SuppressWarnings("removal") SecurityManager s, Class<?> clazz) {
	// check proxy interfaces if the given class is a proxy class
	if (Proxy.isProxyClass(clazz)) {
	for (Class<?> intf : clazz.getInterfaces()) {
	privateCheckPackageAccess(s, intf);
	}
	}
	}
	/**
	* Access check on the interfaces that a proxy class implements and throw
	* {@code SecurityException} if it accesses a restricted package from
	* the caller's class loader.
	*
	* @param ccl the caller's class loader
	* @param interfaces the list of interfaces that a proxy class implements
	*/
	public static void checkProxyPackageAccess(ClassLoader ccl,
	Class<?>... interfaces)
	{
	@SuppressWarnings("removal")
	SecurityManager sm = System.getSecurityManager();
	if (sm != null) {
	for (Class<?> intf : interfaces) {
	ClassLoader cl = intf.getClassLoader();
	if (needsPackageAccessCheck(ccl, cl)) {
	privateCheckPackageAccess(sm, intf);
	}
	}
	}
	}

	// Note that bytecode instrumentation tools may exclude 'sun.*'
	// classes but not generated proxy classes and so keep it in com.sun.*
	public static final String PROXY_PACKAGE = "com.sun.proxy";

	/**
	* Test if the given class is a proxy class that implements
	* non-public interface. Such proxy class may be in a non-restricted
	* package that bypasses checkPackageAccess.
	*/
	public static boolean isNonPublicProxyClass(Class<?> cls) {
	if (!Proxy.isProxyClass(cls)) {
	return false;
	}
	return !Modifier.isPublic(cls.getModifiers());
	}

	/**
	* Check if the given method is a method declared in the proxy interface
	* implemented by the given proxy instance.
	*
	* @param proxy a proxy instance
	* @param method an interface method dispatched to a InvocationHandler
	*
	* @throws IllegalArgumentException if the given proxy or method is invalid.
	*/
	public static void checkProxyMethod(Object proxy, Method method) {
	// check if it is a valid proxy instance
	if (proxy == null \|\| !Proxy.isProxyClass(proxy.getClass())) {
	throw new IllegalArgumentException("Not a Proxy instance");
	}
	if (Modifier.isStatic(method.getModifiers())) {
	throw new IllegalArgumentException("Can't handle static method");
	}

	Class<?> c = method.getDeclaringClass();
	if (c == Object.class) {
	String name = method.getName();
	if (name.equals("hashCode") \|\| name.equals("equals") \|\| name.equals("toString")) {
	return;
	}
	}

	if (isSuperInterface(proxy.getClass(), c)) {
	return;
	}

	// disallow any method not declared in one of the proxy interfaces
	throw new IllegalArgumentException("Can't handle: " + method);
	}

	private static boolean isSuperInterface(Class<?> c, Class<?> intf) {
	for (Class<?> i : c.getInterfaces()) {
	if (i == intf) {
	return true;
	}
	if (isSuperInterface(i, intf)) {
	return true;
	}
	}
	return false;
	}

	}

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