Injector.java
/*
* Copyright (c) 1997, 2022 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0, which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.glassfish.jaxb.runtime.v2.runtime.reflect.opt;
import org.glassfish.jaxb.runtime.v2.runtime.reflect.Accessor;
import java.lang.ref.WeakReference;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.security.*;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;
import java.util.WeakHashMap;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* A {@link ClassLoader} used to "inject" optimized accessor classes
* into the VM.
*
* <p>
* Its parent class loader needs to be set to the one that can see the user
* class.
*
* @author Kohsuke Kawaguchi
*/
final class Injector {
/**
* {@link Injector}s keyed by their parent {@link ClassLoader}.
*
* We only need one injector per one user class loader.
*/
private static final ReentrantReadWriteLock irwl = new ReentrantReadWriteLock();
private static final Lock ir = irwl.readLock();
private static final Lock iw = irwl.writeLock();
private static final Map<ClassLoader, WeakReference<Injector>> injectors =
new WeakHashMap<>();
private static final Logger logger = Logger.getLogger(Injector.class.getName());
/**
* Injects a new class into the given class loader.
*
* @return null
* if it fails to inject.
*/
static Class inject(ClassLoader cl, String className, byte[] image) {
Injector injector = get(cl);
if (injector != null) {
return injector.inject(className, image);
} else {
return null;
}
}
/**
* Returns the already injected class, or null.
*/
static Class find(ClassLoader cl, String className) {
Injector injector = get(cl);
if (injector != null) {
return injector.find(className);
} else {
return null;
}
}
/**
* Gets or creates an for the given class loader.
*
* @return null
* if it fails.
*/
private static Injector get(ClassLoader cl) {
Injector injector = null;
WeakReference<Injector> wr;
ir.lock();
try {
wr = injectors.get(cl);
} finally {
ir.unlock();
}
if (wr != null) {
injector = wr.get();
}
if (injector == null) {
try {
wr = new WeakReference<>(injector = new Injector(cl));
iw.lock();
try {
if (!injectors.containsKey(cl)) {
injectors.put(cl, wr);
}
} finally {
iw.unlock();
}
} catch (SecurityException e) {
logger.log(Level.FINE, "Unable to set up a back-door for the injector", e);
return null;
}
}
return injector;
}
/**
* Injected classes keyed by their names.
*/
private final Map<String, Class> classes = new HashMap<>();
private final ReentrantReadWriteLock rwl = new ReentrantReadWriteLock();
private final Lock r = rwl.readLock();
private final Lock w = rwl.writeLock();
private final ClassLoader parent;
/**
* True if this injector is capable of injecting accessors.
* False otherwise, which happens if this classloader can't see {@link Accessor}.
*/
private final boolean loadable;
private static Method defineClass;
private static Method resolveClass;
private static Method findLoadedClass;
private static Object U;
static {
try {
Method[] m = AccessController.doPrivileged(
new PrivilegedAction<>() {
@Override
public Method[] run() {
return new Method[]{
getMethod(ClassLoader.class, "defineClass", String.class, byte[].class, Integer.TYPE, Integer.TYPE),
getMethod(ClassLoader.class, "resolveClass", Class.class),
getMethod(ClassLoader.class, "findLoadedClass", String.class)
};
}
}
);
defineClass = m[0];
resolveClass = m[1];
findLoadedClass = m[2];
} catch (Throwable t) {
try {
U = AccessController.doPrivileged(new PrivilegedExceptionAction() {
@Override
public Object run() throws Exception {
Class u = classForNames("sun.misc.Unsafe", "jdk.internal.misc.Unsafe");
Field theUnsafe = u.getDeclaredField("theUnsafe");
theUnsafe.setAccessible(true);
return theUnsafe.get(null);
}
});
defineClass = AccessController.doPrivileged(new PrivilegedExceptionAction<>() {
@Override
public Method run() throws Exception {
try {
return U.getClass().getMethod("defineClass",
String.class,
byte[].class,
Integer.TYPE,
Integer.TYPE,
ClassLoader.class,
ProtectionDomain.class);
} catch (NoSuchMethodException | SecurityException ex) {
throw ex;
}
}
});
} catch (SecurityException | PrivilegedActionException ex) {
Logger.getLogger(Injector.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
private static Class classForNames(String... names) throws ClassNotFoundException {
for (String name : names) {
try {
return Class.forName(name);
} catch (ClassNotFoundException e) {
}
}
throw new ClassNotFoundException(
String.format("No class found for supplied FQDNs %s",
Arrays.toString(names)));
}
private static Method getMethod(final Class<?> c, final String methodname, final Class<?>... params) {
try {
Method m = c.getDeclaredMethod(methodname, params);
m.setAccessible(true);
return m;
} catch (NoSuchMethodException e) {
throw new NoSuchMethodError(e.getMessage());
}
}
private Injector(ClassLoader parent) {
this.parent = parent;
assert parent != null;
boolean loadableCheck = false;
try {
loadableCheck = parent.loadClass(Accessor.class.getName()) == Accessor.class;
} catch (ClassNotFoundException e) {
// not loadable
}
this.loadable = loadableCheck;
}
@SuppressWarnings("LockAcquiredButNotSafelyReleased")
private Class inject(String className, byte[] image) {
if (!loadable) // this injector cannot inject anything
{
return null;
}
boolean wlocked = false;
boolean rlocked = false;
try {
r.lock();
rlocked = true;
Class c = classes.get(className);
// Unlock now during the findLoadedClass process to avoid
// deadlocks
r.unlock();
rlocked = false;
//find loaded class from classloader
if (c == null && findLoadedClass != null) {
try {
c = (Class) findLoadedClass.invoke(parent, className.replace('/', '.'));
} catch (IllegalArgumentException | IllegalAccessException e) {
logger.log(Level.FINE, "Unable to find " + className, e);
} catch (InvocationTargetException e) {
Throwable t = e.getTargetException();
logger.log(Level.FINE, "Unable to find " + className, t);
}
if (c != null) {
w.lock();
wlocked = true;
classes.put(className, c);
w.unlock();
wlocked = false;
return c;
}
}
if (c == null) {
r.lock();
rlocked = true;
c = classes.get(className);
// Unlock now during the define/resolve process to avoid
// deadlocks
r.unlock();
rlocked = false;
if (c == null) {
// we need to inject a class into the
try {
if (resolveClass != null) {
c = (Class) defineClass.invoke(parent, className.replace('/', '.'), image, 0, image.length);
resolveClass.invoke(parent, c);
} else {
c = (Class) defineClass.invoke(U, className.replace('/', '.'), image, 0, image.length, parent, Injector.class.getProtectionDomain());
}
} catch (IllegalAccessException | LinkageError | SecurityException e) {
logger.log(Level.FINE, "Unable to inject " + className, e);
return null;
} catch (InvocationTargetException e) {
Throwable t = e.getTargetException();
if (t instanceof LinkageError) {
logger.log(Level.FINE, "duplicate class definition bug occured? Please report this : " + className, t);
} else {
logger.log(Level.FINE, "Unable to inject " + className, t);
}
return null;
}
w.lock();
wlocked = true;
// During the time we were unlocked, we could have tried to
// load the class from more than one thread. Check now to see
// if someone else beat us to registering this class
if (!classes.containsKey(className)) {
classes.put(className, c);
}
w.unlock();
wlocked = false;
}
}
return c;
} finally {
if (rlocked) {
r.unlock();
}
if (wlocked) {
w.unlock();
}
}
}
private Class find(String className) {
r.lock();
try {
return classes.get(className);
} finally {
r.unlock();
}
}
}