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* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
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package jdk.nashorn.internal.runtime.linker;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Module;
import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.ProtectionDomain;
import java.security.SecureClassLoader;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import jdk.dynalink.beans.StaticClass;
import jdk.nashorn.internal.codegen.DumpBytecode;
import jdk.nashorn.internal.runtime.Context;
import jdk.nashorn.internal.runtime.JSType;
import jdk.nashorn.internal.runtime.ScriptFunction;
import jdk.nashorn.internal.runtime.ScriptObject;
/**
* This class encapsulates the bytecode of the adapter class and can be used to load it into the JVM as an actual Class.
* It can be invoked repeatedly to create multiple adapter classes from the same bytecode; adapter classes that have
* class-level overrides must be re-created for every set of such overrides. Note that while this class is named
* "class loader", it does not, in fact, extend {@code ClassLoader}, but rather uses them internally. Instances of this
* class are normally created by {@code JavaAdapterBytecodeGenerator}.
*/
final class JavaAdapterClassLoader {
private static final Module NASHORN_MODULE = Context.class.getModule();
private static final AccessControlContext CREATE_LOADER_ACC_CTXT = ClassAndLoader.createPermAccCtxt("createClassLoader");
private static final AccessControlContext GET_CONTEXT_ACC_CTXT = ClassAndLoader.createPermAccCtxt(Context.NASHORN_GET_CONTEXT);
private static final Collection<String> VISIBLE_INTERNAL_CLASS_NAMES = Collections.unmodifiableCollection(new HashSet<>(
Arrays.asList(JavaAdapterServices.class.getName(), ScriptObject.class.getName(), ScriptFunction.class.getName(), JSType.class.getName())));
private final String className;
private final byte[] classBytes;
JavaAdapterClassLoader(final String className, final byte[] classBytes) {
this.className = className.replace('/', '.');
this.classBytes = classBytes;
}
/**
* Loads the generated adapter class into the JVM.
* @param parentLoader the parent class loader for the generated class loader
* @param protectionDomain the protection domain for the generated class
* @return the generated adapter class
*/
StaticClass generateClass(final ClassLoader parentLoader, final ProtectionDomain protectionDomain) {
assert protectionDomain != null;
return AccessController.doPrivileged(new PrivilegedAction<StaticClass>() {
@Override
public StaticClass run() {
try {
return StaticClass.forClass(Class.forName(className, true, createClassLoader(parentLoader, protectionDomain)));
} catch (final ClassNotFoundException e) {
throw new AssertionError(e); // cannot happen
}
}
}, CREATE_LOADER_ACC_CTXT);
}
// Note that the adapter class is created in the protection domain of the class/interface being
// extended/implemented, and only the privileged global setter action class is generated in the protection domain
// of Nashorn itself. Also note that the creation and loading of the global setter is deferred until it is
// required by JVM linker, which will only happen on first invocation of any of the adapted method. We could defer
// it even more by separating its invocation into a separate static method on the adapter class, but then someone
// with ability to introspect on the class and use setAccessible(true) on it could invoke the method. It's a
// security tradeoff...
private ClassLoader createClassLoader(final ClassLoader parentLoader, final ProtectionDomain protectionDomain) {
return new SecureClassLoader(parentLoader) {
private final ClassLoader myLoader = getClass().getClassLoader();
// the unnamed module into which adapter is loaded!
private final Module adapterModule = getUnnamedModule();
{
// specific exports from nashorn to the new adapter module
NASHORN_MODULE.addExports("jdk.nashorn.internal.runtime", adapterModule);
NASHORN_MODULE.addExports("jdk.nashorn.internal.runtime.linker", adapterModule);
// nashorn should be be able to read methods of classes loaded in adapter module
NASHORN_MODULE.addReads(adapterModule);
}
@Override
public Class<?> loadClass(final String name, final boolean resolve) throws ClassNotFoundException {
try {
Context.checkPackageAccess(name);
return super.loadClass(name, resolve);
} catch (final SecurityException se) {
// we may be implementing an interface or extending a class that was
// loaded by a loader that prevents package.access. If so, it'd throw
// SecurityException for nashorn's classes!. For adapter's to work, we
// should be able to refer to the few classes it needs in its implementation.
if(VISIBLE_INTERNAL_CLASS_NAMES.contains(name)) {
return myLoader != null? myLoader.loadClass(name) : Class.forName(name, false, myLoader);
}
throw se;
}
}
@Override
protected Class<?> findClass(final String name) throws ClassNotFoundException {
if(name.equals(className)) {
assert classBytes != null : "what? already cleared .class bytes!!";
final Context ctx = AccessController.doPrivileged(new PrivilegedAction<Context>() {
@Override
public Context run() {
return Context.getContext();
}
}, GET_CONTEXT_ACC_CTXT);
DumpBytecode.dumpBytecode(ctx.getEnv(), ctx.getLogger(jdk.nashorn.internal.codegen.Compiler.class), classBytes, name);
return defineClass(name, classBytes, 0, classBytes.length, protectionDomain);
}
throw new ClassNotFoundException(name);
}
};
}
}