/*
* Copyright (c) 2005, 2012, 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.Modifier;
import java.lang.reflect.Proxy;
import sun.reflect.Reflection;
public final class ReflectUtil {
private ReflectUtil() {
}
public static Class<?> forName(String name)
throws ClassNotFoundException {
checkPackageAccess(name);
return Class.forName(name);
}
public static Object newInstance(Class<?> cls)
throws InstantiationException, IllegalAccessException {
checkPackageAccess(cls);
return cls.newInstance();
}
/*
* Reflection.ensureMemberAccess is overly-restrictive
* due to a bug. We awkwardly work around it for now.
*/
public static void ensureMemberAccess(Class<?> currentClass,
Class<?> memberClass,
Object target,
int modifiers)
throws IllegalAccessException
{
if (target == null && Modifier.isProtected(modifiers)) {
int mods = modifiers;
mods = mods & (~Modifier.PROTECTED);
mods = mods | Modifier.PUBLIC;
/*
* See if we fail because of class modifiers
*/
Reflection.ensureMemberAccess(currentClass,
memberClass,
target,
mods);
try {
/*
* We're still here so class access was ok.
* Now try with default field access.
*/
mods = mods & (~Modifier.PUBLIC);
Reflection.ensureMemberAccess(currentClass,
memberClass,
target,
mods);
/*
* We're still here so access is ok without
* checking for protected.
*/
return;
} catch (IllegalAccessException e) {
/*
* Access failed but we're 'protected' so
* if the test below succeeds then we're ok.
*/
if (isSubclassOf(currentClass, memberClass)) {
return;
} else {
throw e;
}
}
} else {
Reflection.ensureMemberAccess(currentClass,
memberClass,
target,
modifiers);
}
}
private static boolean isSubclassOf(Class<?> queryClass,
Class<?> ofClass)
{
while (queryClass != null) {
if (queryClass == ofClass) {
return true;
}
queryClass = queryClass.getSuperclass();
}
return false;
}
/**
* 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) {
checkPackageAccess(clazz.getName());
if (isNonPublicProxyClass(clazz)) {
checkProxyPackageAccess(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) {
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) {
SecurityManager s = System.getSecurityManager();
if (s != null) {
// check proxy interfaces if the given class is a proxy class
if (Proxy.isProxyClass(clazz)) {
for (Class<?> intf : clazz.getInterfaces()) {
checkPackageAccess(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)
{
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
for (Class<?> intf : interfaces) {
ClassLoader cl = intf.getClassLoader();
if (needsPackageAccessCheck(ccl, cl)) {
checkPackageAccess(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) {
String name = cls.getName();
int i = name.lastIndexOf('.');
String pkg = (i != -1) ? name.substring(0, i) : "";
return Proxy.isProxyClass(cls) && !pkg.equals(PROXY_PACKAGE);
}
}