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/*
* Copyright (c) 2010, 2013, 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 jdk.nashorn.internal.runtime.linker;
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import jdk.internal.dynalink.beans.BeansLinker;
import jdk.internal.dynalink.linker.ConversionComparator.Comparison;
import jdk.internal.dynalink.linker.GuardedInvocation;
import jdk.internal.dynalink.linker.GuardingDynamicLinker;
import jdk.internal.dynalink.linker.LinkRequest;
import jdk.internal.dynalink.linker.LinkerServices;
import jdk.internal.dynalink.support.Lookup;
import jdk.nashorn.internal.runtime.ConsString;
/**
* This linker delegates to a {@code BeansLinker} but passes it a special linker services object that has a modified
* {@code asType} method that will ensure that we never pass internal engine objects that should not be externally
* observable (currently only ConsString) to Java APIs, but rather that we flatten it into a String. We can't just add
* this functionality as custom converters via {@code GuaardingTypeConverterFactory}, since they are not consulted when
* the target method handle parameter signature is {@code Object}.
*/
public class NashornBeansLinker implements GuardingDynamicLinker {
private static final MethodHandle EXPORT_ARGUMENT = new Lookup(MethodHandles.lookup()).findOwnStatic("exportArgument", Object.class, Object.class);
private final BeansLinker beansLinker = new BeansLinker();
@Override
public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest, final LinkerServices linkerServices) throws Exception {
return getGuardedInvocation(beansLinker, linkRequest, linkerServices);
}
/**
* Delegates to the specified linker but injects its linker services wrapper so that it will apply all special
* conversions that this class does.
* @param delegateLinker the linker to which the actual work is delegated to.
* @param linkRequest the delegated link request
* @param linkerServices the original link services that will be augmented with special conversions
* @return the guarded invocation from the delegate, possibly augmented with special conversions
* @throws Exception if the delegate throws an exception
*/
public static GuardedInvocation getGuardedInvocation(final GuardingDynamicLinker delegateLinker, final LinkRequest linkRequest, final LinkerServices linkerServices) throws Exception {
return delegateLinker.getGuardedInvocation(linkRequest, new NashornBeansLinkerServices(linkerServices));
}
@SuppressWarnings("unused")
private static Object exportArgument(final Object arg) {
return arg instanceof ConsString ? arg.toString() : arg;
}
private static class NashornBeansLinkerServices implements LinkerServices {
private final LinkerServices linkerServices;
NashornBeansLinkerServices(final LinkerServices linkerServices) {
this.linkerServices = linkerServices;
}
@Override
public MethodHandle asType(final MethodHandle handle, final MethodType fromType) {
final MethodHandle typed = linkerServices.asType(handle, fromType);
final MethodType handleType = handle.type();
final int paramCount = handleType.parameterCount();
assert fromType.parameterCount() == handleType.parameterCount();
MethodHandle[] filters = null;
for(int i = 0; i < paramCount; ++i) {
if(shouldConvert(handleType.parameterType(i), fromType.parameterType(i))) {
if(filters == null) {
filters = new MethodHandle[paramCount];
}
filters[i] = EXPORT_ARGUMENT;
}
}
return filters != null ? MethodHandles.filterArguments(typed, 0, filters) : typed;
}
private static boolean shouldConvert(final Class<?> handleType, final Class<?> fromType) {
return handleType == Object.class && fromType == Object.class;
}
@Override
public MethodHandle getTypeConverter(final Class<?> sourceType, final Class<?> targetType) {
return linkerServices.getTypeConverter(sourceType, targetType);
}
@Override
public boolean canConvert(final Class<?> from, final Class<?> to) {
return linkerServices.canConvert(from, to);
}
@Override
public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest) throws Exception {
return linkerServices.getGuardedInvocation(linkRequest);
}
@Override
public Comparison compareConversion(final Class<?> sourceType, final Class<?> targetType1, final Class<?> targetType2) {
return linkerServices.compareConversion(sourceType, targetType1, targetType2);
}
}
}
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