manifold.ext.rt.proxy.Proxy Maven / Gradle / Ivy
/*
* Copyright (c) 2021 - Manifold Systems LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package manifold.ext.rt.proxy;
import java.lang.ref.WeakReference;
import java.lang.reflect.*;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.*;
import java.util.concurrent.atomic.AtomicLong;
import java.util.function.BiFunction;
import manifold.util.JreUtil;
import manifold.util.ReflectUtil;
import sun.reflect.CallerSensitive;
import sun.reflect.Reflection;
/**
* Adapted from java.lang.reflect.Proxy to remove the CHECKCAST instruction if the return type is a Structural interface,
* otherwise the proxy method call fails on such a call because the return value doesn't nominally implement the
* interface.
*
* Note this Proxy class is an amalgamation of the Java 8 and Java 9+ Proxy classes to support both with a single
* codebase, as manifold does. This Proxy class is mostly the Java 8 one, but handles modules when running in a
* Java 9+ VM by calling into the Java 9+ Proxy.ProxyBuilder to provide module for the proxy.
*/
public class Proxy implements java.io.Serializable {
private static final long serialVersionUID = -2222568056686623797L;
/** parameter types of a proxy class constructor */
private static final Class[] constructorParams =
{ InvocationHandler.class };
/**
* a cache of proxy classes
*/
private static final WeakCache[], Class>
proxyClassCache = new WeakCache<>(new KeyFactory(), new ProxyClassFactory());
/**
* the invocation handler for this proxy instance.
* @serial
*/
protected InvocationHandler h;
/**
* Prohibits instantiation.
*/
private Proxy() {
}
/**
* Constructs a new {@code Proxy} instance from a subclass
* (typically, a dynamic proxy class) with the specified value
* for its invocation handler.
*
* @param h the invocation handler for this proxy instance
*
* @throws NullPointerException if the given invocation handler, {@code h},
* is {@code null}.
*/
protected Proxy(InvocationHandler h) {
Objects.requireNonNull(h);
this.h = h;
}
/**
* Returns the {@code java.lang.Class} object for a proxy class
* given a class loader and an array of interfaces. The proxy class
* will be defined by the specified class loader and will implement
* all of the supplied interfaces. If any of the given interfaces
* is non-public, the proxy class will be non-public. If a proxy class
* for the same permutation of interfaces has already been defined by the
* class loader, then the existing proxy class will be returned; otherwise,
* a proxy class for those interfaces will be generated dynamically
* and defined by the class loader.
*
* There are several restrictions on the parameters that may be
* passed to {@code Proxy.getProxyClass}:
*
*
* - All of the {@code Class} objects in the
* {@code interfaces} array must represent interfaces, not
* classes or primitive types.
*
*
- No two elements in the {@code interfaces} array may
* refer to identical {@code Class} objects.
*
*
- All of the interface types must be visible by name through the
* specified class loader. In other words, for class loader
* {@code cl} and every interface {@code i}, the following
* expression must be true:
*
* Class.forName(i.getName(), false, cl) == i
*
*
* - All non-public interfaces must be in the same package;
* otherwise, it would not be possible for the proxy class to
* implement all of the interfaces, regardless of what package it is
* defined in.
*
*
- For any set of member methods of the specified interfaces
* that have the same signature:
*
* - If the return type of any of the methods is a primitive
* type or void, then all of the methods must have that same
* return type.
*
- Otherwise, one of the methods must have a return type that
* is assignable to all of the return types of the rest of the
* methods.
*
*
* - The resulting proxy class must not exceed any limits imposed
* on classes by the virtual machine. For example, the VM may limit
* the number of interfaces that a class may implement to 65535; in
* that case, the size of the {@code interfaces} array must not
* exceed 65535.
*
*
* If any of these restrictions are violated,
* {@code Proxy.getProxyClass} will throw an
* {@code IllegalArgumentException}. If the {@code interfaces}
* array argument or any of its elements are {@code null}, a
* {@code NullPointerException} will be thrown.
*
*
Note that the order of the specified proxy interfaces is
* significant: two requests for a proxy class with the same combination
* of interfaces but in a different order will result in two distinct
* proxy classes.
*
* @param loader the class loader to define the proxy class
* @param interfaces the list of interfaces for the proxy class
* to implement
* @return a proxy class that is defined in the specified class loader
* and that implements the specified interfaces
* @throws IllegalArgumentException if any of the restrictions on the
* parameters that may be passed to {@code getProxyClass}
* are violated
* @throws SecurityException if a security manager, s, is present
* and any of the following conditions is met:
*
* - the given {@code loader} is {@code null} and
* the caller's class loader is not {@code null} and the
* invocation of {@link SecurityManager#checkPermission
* s.checkPermission} with
* {@code RuntimePermission("getClassLoader")} permission
* denies access.
* - for each proxy interface, {@code intf},
* the caller's class loader is not the same as or an
* ancestor of the class loader for {@code intf} and
* invocation of {@link SecurityManager#checkPackageAccess
* s.checkPackageAccess()} denies access to {@code intf}.
*
* @throws NullPointerException if the {@code interfaces} array
* argument or any of its elements are {@code null}
*/
@CallerSensitive
public static Class getProxyClass(ClassLoader loader,
Class... interfaces)
throws IllegalArgumentException
{
final Class[] intfs = interfaces.clone();
return getProxyClass0(loader, intfs);
}
/*
* Check permissions required to create a Proxy class.
*
* To define a proxy class, it performs the access checks as in
* Class.forName (VM will invoke ClassLoader.checkPackageAccess):
* 1. "getClassLoader" permission check if loader == null
* 2. checkPackageAccess on the interfaces it implements
*
* To get a constructor and new instance of a proxy class, it performs
* the package access check on the interfaces it implements
* as in Class.getConstructor.
*
* If an interface is non-public, the proxy class must be defined by
* the defining loader of the interface. If the caller's class loader
* is not the same as the defining loader of the interface, the VM
* will throw IllegalAccessError when the generated proxy class is
* being defined via the defineClass0 method.
*/
private static void checkProxyAccess(Class caller,
ClassLoader loader,
Class... interfaces)
{
}
/**
* Generate a proxy class. Must call the checkProxyAccess method
* to perform permission checks before calling this.
*/
private static Class getProxyClass0(ClassLoader loader,
Class... interfaces) {
if (interfaces.length > 65535) {
throw new IllegalArgumentException("interface limit exceeded");
}
// If the proxy class defined by the given loader implementing
// the given interfaces exists, this will simply return the cached copy;
// otherwise, it will create the proxy class via the ProxyClassFactory
return proxyClassCache.get(loader, interfaces);
}
/*
* a key used for proxy class with 0 implemented interfaces
*/
private static final Object key0 = new Object();
/*
* Key1 and Key2 are optimized for the common use of dynamic proxies
* that implement 1 or 2 interfaces.
*/
/*
* a key used for proxy class with 1 implemented interface
*/
private static final class Key1 extends WeakReference> {
private final int hash;
Key1(Class intf) {
super(intf);
this.hash = intf.hashCode();
}
@Override
public int hashCode() {
return hash;
}
@Override
public boolean equals(Object obj) {
Class intf;
return this == obj ||
obj != null &&
obj.getClass() == Key1.class &&
(intf = get()) != null &&
intf == ((Key1) obj).get();
}
}
/*
* a key used for proxy class with 2 implemented interfaces
*/
private static final class Key2 extends WeakReference> {
private final int hash;
private final WeakReference> ref2;
Key2(Class intf1, Class intf2) {
super(intf1);
hash = 31 * intf1.hashCode() + intf2.hashCode();
ref2 = new WeakReference>(intf2);
}
@Override
public int hashCode() {
return hash;
}
@Override
public boolean equals(Object obj) {
Class intf1, intf2;
return this == obj ||
obj != null &&
obj.getClass() == Key2.class &&
(intf1 = get()) != null &&
intf1 == ((Key2) obj).get() &&
(intf2 = ref2.get()) != null &&
intf2 == ((Key2) obj).ref2.get();
}
}
/*
* a key used for proxy class with any number of implemented interfaces
* (used here for 3 or more only)
*/
private static final class KeyX {
private final int hash;
private final WeakReference>[] refs;
@SuppressWarnings("unchecked")
KeyX(Class[] interfaces) {
hash = Arrays.hashCode(interfaces);
refs = (WeakReference>[])new WeakReference[interfaces.length];
for (int i = 0; i < interfaces.length; i++) {
refs[i] = new WeakReference<>(interfaces[i]);
}
}
@Override
public int hashCode() {
return hash;
}
@Override
public boolean equals(Object obj) {
return this == obj ||
obj != null &&
obj.getClass() == KeyX.class &&
equals(refs, ((KeyX) obj).refs);
}
private static boolean equals(WeakReference>[] refs1,
WeakReference>[] refs2) {
if (refs1.length != refs2.length) {
return false;
}
for (int i = 0; i < refs1.length; i++) {
Class intf = refs1[i].get();
if (intf == null || intf != refs2[i].get()) {
return false;
}
}
return true;
}
}
/**
* A function that maps an array of interfaces to an optimal key where
* Class objects representing interfaces are weakly referenced.
*/
private static final class KeyFactory
implements BiFunction[], Object>
{
@Override
public Object apply(ClassLoader classLoader, Class[] interfaces) {
switch (interfaces.length) {
case 1: return new Key1(interfaces[0]); // the most frequent
case 2: return new Key2(interfaces[0], interfaces[1]);
case 0: return key0;
default: return new KeyX(interfaces);
}
}
}
/**
* A factory function that generates, defines and returns the proxy class given
* the ClassLoader and array of interfaces.
*/
private static final class ProxyClassFactory
implements BiFunction[], Class>
{
// prefix for all proxy class names
private static final String proxyClassNamePrefix = "$ManProxy";
// next number to use for generation of unique proxy class names
private static final AtomicLong nextUniqueNumber = new AtomicLong();
@Override
public Class apply(ClassLoader loader, Class[] interfaces) {
Map, Boolean> interfaceSet = new IdentityHashMap<>(interfaces.length);
for (Class intf : interfaces) {
/*
* Verify that the class loader resolves the name of this
* interface to the same Class object.
*/
Class interfaceClass = null;
try {
interfaceClass = Class.forName(intf.getName(), false, loader);
} catch (ClassNotFoundException e) {
}
if (interfaceClass != intf) {
throw new IllegalArgumentException(
intf + " is not visible from class loader");
}
/*
* Verify that the Class object actually represents an
* interface.
*/
if (!interfaceClass.isInterface()) {
throw new IllegalArgumentException(
interfaceClass.getName() + " is not an interface");
}
/*
* Verify that this interface is not a duplicate.
*/
if (interfaceSet.put(interfaceClass, Boolean.TRUE) != null) {
throw new IllegalArgumentException(
"repeated interface: " + interfaceClass.getName());
}
}
String proxyPkg = null; // package to define proxy class in
int accessFlags = Modifier.PUBLIC | Modifier.FINAL;
/*
* Record the package of a non-public proxy interface so that the
* proxy class will be defined in the same package. Verify that
* all non-public proxy interfaces are in the same package.
*/
for (Class intf : interfaces) {
int flags = intf.getModifiers();
if (!Modifier.isPublic(flags)) {
accessFlags = Modifier.FINAL;
String name = intf.getName();
int n = name.lastIndexOf('.');
String pkg = ((n == -1) ? "" : name.substring(0, n + 1));
if (proxyPkg == null) {
proxyPkg = pkg;
} else if (!pkg.equals(proxyPkg)) {
throw new IllegalArgumentException(
"non-public interfaces from different packages");
}
}
}
// if Java 9+, get the module from java.lang.reflect.Proxy$ProxyBuilder
Object proxyModule = null;
if( !JreUtil.isJava8() )
{
if( proxyPkg != null && proxyPkg.endsWith( "." ) )
{
proxyPkg = proxyPkg.substring( 0, proxyPkg.length()-1 );
}
// get a module for the proxy
Object builder = ReflectUtil.constructor( "java.lang.reflect.Proxy$ProxyBuilder", ClassLoader.class, List.class )
.newInstance( loader, Arrays.asList( interfaces ) );
if( JreUtil.isJava20orLater() )
{
proxyModule = ReflectUtil.field( ReflectUtil.field( builder, "context" ).get(), "module" ).get();
}
else
{
proxyModule = ReflectUtil.field( builder, "module" ).get();
}
String moduleName = (String)ReflectUtil.method( proxyModule, "getName" ).invoke();
Class moduleClass = ReflectUtil.type( "java.lang.Module" );
// manifold.ext.rt module creates proxy instances, allow it to read from the proxy's module and access the proxy's package
Object manifoldExtRtModule = ReflectUtil.method( (Object)Proxy.class, "getModule" ).invoke();
ReflectUtil.method( "jdk.internal.module.Modules", "addReads", moduleClass, moduleClass )
.invokeStatic( proxyModule, manifoldExtRtModule );
if( proxyPkg == null )
{
proxyPkg = (boolean)ReflectUtil.method( proxyModule, "isNamed" ).invoke()
? "com.sun.proxy" + "." + moduleName
: "com.sun.proxy";
}
ReflectUtil.method( "jdk.internal.module.Modules", "addExports", moduleClass, String.class, moduleClass )
.invokeStatic( proxyModule, proxyPkg, manifoldExtRtModule );
ReflectUtil.method( "jdk.internal.module.Modules", "addOpens", moduleClass, String.class, moduleClass )
.invokeStatic( proxyModule, proxyPkg, manifoldExtRtModule );
proxyPkg += '.';
}
if( proxyPkg == null )
{
proxyPkg = "com.sun.proxy" + '.';
}
/*
* Choose a name for the proxy class to generate.
*/
long num = nextUniqueNumber.getAndIncrement();
String proxyName = proxyPkg + proxyClassNamePrefix + num;
/*
* Generate the specified proxy class.
*/
byte[] proxyClassFile = ProxyGenerator.generateProxyClass(
proxyName, interfaces, accessFlags);
try {
return defineProxyClass( proxyModule, proxyName, proxyClassFile, 0, proxyClassFile.length, loader );
} catch (ClassFormatError e) {
/*
* A ClassFormatError here means that (barring bugs in the
* proxy class generation code) there was some other
* invalid aspect of the arguments supplied to the proxy
* class creation (such as virtual machine limitations
* exceeded).
*/
throw new IllegalArgumentException(e.toString());
}
}
}
/**
* Returns an instance of a proxy class for the specified interfaces
* that dispatches method invocations to the specified invocation
* handler.
*
* {@code Proxy.newProxyInstance} throws
* {@code IllegalArgumentException} for the same reasons that
* {@code Proxy.getProxyClass} does.
*
* @param loader the class loader to define the proxy class
* @param interfaces the list of interfaces for the proxy class
* to implement
* @param h the invocation handler to dispatch method invocations to
* @return a proxy instance with the specified invocation handler of a
* proxy class that is defined by the specified class loader
* and that implements the specified interfaces
* @throws IllegalArgumentException if any of the restrictions on the
* parameters that may be passed to {@code getProxyClass}
* are violated
* @throws SecurityException if a security manager, s, is present
* and any of the following conditions is met:
*
* - the given {@code loader} is {@code null} and
* the caller's class loader is not {@code null} and the
* invocation of {@link SecurityManager#checkPermission
* s.checkPermission} with
* {@code RuntimePermission("getClassLoader")} permission
* denies access;
* - for each proxy interface, {@code intf},
* the caller's class loader is not the same as or an
* ancestor of the class loader for {@code intf} and
* invocation of {@link SecurityManager#checkPackageAccess
* s.checkPackageAccess()} denies access to {@code intf};
* - any of the given proxy interfaces is non-public and the
* caller class is not in the same {@linkplain Package runtime package}
* as the non-public interface and the invocation of
* {@link SecurityManager#checkPermission s.checkPermission} with
* {@code ReflectPermission("newProxyInPackage.{package name}")}
* permission denies access.
*
* @throws NullPointerException if the {@code interfaces} array
* argument or any of its elements are {@code null}, or
* if the invocation handler, {@code h}, is
* {@code null}
*/
@CallerSensitive
public static Object newProxyInstance(ClassLoader loader,
Class[] interfaces,
InvocationHandler h)
throws IllegalArgumentException
{
Objects.requireNonNull(h);
final Class[] intfs = interfaces.clone();
final SecurityManager sm = System.getSecurityManager();
if (sm != null) {
checkProxyAccess(Reflection.getCallerClass(), loader, intfs);
}
/*
* Look up or generate the designated proxy class.
*/
Class cl = getProxyClass0(loader, intfs);
/*
* Invoke its constructor with the designated invocation handler.
*/
try {
if (sm != null) {
checkNewProxyPermission(Reflection.getCallerClass(), cl);
}
final Constructor cons = cl.getConstructor(constructorParams);
final InvocationHandler ih = h;
if (!Modifier.isPublic(cl.getModifiers())) {
AccessController.doPrivileged(new PrivilegedAction() {
public Void run() {
cons.setAccessible(true);
return null;
}
});
}
return cons.newInstance(new Object[]{h});
} catch (IllegalAccessException|InstantiationException e) {
throw new InternalError(e.toString(), e);
} catch ( InvocationTargetException e) {
Throwable t = e.getCause();
if (t instanceof RuntimeException) {
throw (RuntimeException) t;
} else {
throw new InternalError(t.toString(), t);
}
} catch (NoSuchMethodException e) {
throw new InternalError(e.toString(), e);
}
}
private static void checkNewProxyPermission(Class caller, Class proxyClass) {
}
/**
* Returns true if and only if the specified class was dynamically
* generated to be a proxy class using the {@code getProxyClass}
* method or the {@code newProxyInstance} method.
*
* The reliability of this method is important for the ability
* to use it to make security decisions, so its implementation should
* not just test if the class in question extends {@code Proxy}.
*
* @param cl the class to test
* @return {@code true} if the class is a proxy class and
* {@code false} otherwise
* @throws NullPointerException if {@code cl} is {@code null}
*/
public static boolean isProxyClass(Class cl) {
return java.lang.reflect.Proxy.class.isAssignableFrom(cl) && proxyClassCache.containsValue(cl);
}
/**
* Returns the invocation handler for the specified proxy instance.
*
* @param proxy the proxy instance to return the invocation handler for
* @return the invocation handler for the proxy instance
* @throws IllegalArgumentException if the argument is not a
* proxy instance
* @throws SecurityException if a security manager, s, is present
* and the caller's class loader is not the same as or an
* ancestor of the class loader for the invocation handler
* and invocation of {@link SecurityManager#checkPackageAccess
* s.checkPackageAccess()} denies access to the invocation
* handler's class.
*/
@CallerSensitive
public static InvocationHandler getInvocationHandler(Object proxy)
throws IllegalArgumentException
{
/*
* Verify that the object is actually a proxy instance.
*/
if (!isProxyClass(proxy.getClass())) {
throw new IllegalArgumentException("not a proxy instance");
}
final Proxy p = (Proxy) proxy;
return p.h;
}
public static Class defineProxyClass( Object module, String name, byte[] b, int off, int len, ClassLoader loader )
{
if( !JreUtil.isJava8() )
{
// return NecessaryEvilUtil.getUnsafe().defineClass( name, b, off, len, loader, null );
loader = (ClassLoader)ReflectUtil.method( module, "getClassLoader" ).invoke();
}
return (Class)ReflectUtil.method( loader, "defineClass", String.class, byte[].class, int.class, int.class )
.invoke( name, b, off, len );
}
}