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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.api.scripting.ScriptUtils;
import jdk.nashorn.internal.objects.NativeArray;
import jdk.nashorn.internal.runtime.ConsString;
import jdk.nashorn.internal.runtime.ScriptObject;
import jdk.nashorn.internal.runtime.options.Options;
/**
* 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 ConsString and ScriptObject) 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 {
// System property to control whether to wrap ScriptObject->ScriptObjectMirror for
// Object type arguments of Java method calls, field set and array set.
private static final boolean MIRROR_ALWAYS = Options.getBooleanProperty("nashorn.mirror.always", true);
private static final MethodHandle EXPORT_ARGUMENT;
private static final MethodHandle EXPORT_NATIVE_ARRAY;
private static final MethodHandle EXPORT_SCRIPT_OBJECT;
private static final MethodHandle IMPORT_RESULT;
private static final MethodHandle FILTER_CONSSTRING;
static {
final Lookup lookup = new Lookup(MethodHandles.lookup());
EXPORT_ARGUMENT = lookup.findOwnStatic("exportArgument", Object.class, Object.class);
EXPORT_NATIVE_ARRAY = lookup.findOwnStatic("exportNativeArray", Object.class, NativeArray.class);
EXPORT_SCRIPT_OBJECT = lookup.findOwnStatic("exportScriptObject", Object.class, ScriptObject.class);
IMPORT_RESULT = lookup.findOwnStatic("importResult", Object.class, Object.class);
FILTER_CONSSTRING = lookup.findOwnStatic("consStringFilter", Object.class, Object.class);
}
private final BeansLinker beansLinker = new BeansLinker();
@Override
public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest, final LinkerServices linkerServices) throws Exception {
if (linkRequest.getReceiver() instanceof ConsString) {
// In order to treat ConsString like a java.lang.String we need a link request with a string receiver.
final Object[] arguments = linkRequest.getArguments();
arguments[0] = "";
final LinkRequest forgedLinkRequest = linkRequest.replaceArguments(linkRequest.getCallSiteDescriptor(), arguments);
final GuardedInvocation invocation = getGuardedInvocation(beansLinker, forgedLinkRequest, linkerServices);
// If an invocation is found we add a filter that makes it work for both Strings and ConsStrings.
return invocation == null ? null : invocation.filterArguments(0, FILTER_CONSSTRING);
}
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 exportArgument(arg, MIRROR_ALWAYS);
}
@SuppressWarnings("unused")
private static Object exportNativeArray(final NativeArray arg) {
return exportArgument(arg, MIRROR_ALWAYS);
}
@SuppressWarnings("unused")
private static Object exportScriptObject(final ScriptObject arg) {
return exportArgument(arg, MIRROR_ALWAYS);
}
@SuppressWarnings("unused")
private static Object exportScriptArray(final NativeArray arg) {
return exportArgument(arg, MIRROR_ALWAYS);
}
static Object exportArgument(final Object arg, final boolean mirrorAlways) {
if (arg instanceof ConsString) {
return arg.toString();
} else if (mirrorAlways && arg instanceof ScriptObject) {
return ScriptUtils.wrap((ScriptObject)arg);
} else {
return arg;
}
}
@SuppressWarnings("unused")
private static Object importResult(final Object arg) {
return ScriptUtils.unwrap(arg);
}
@SuppressWarnings("unused")
private static Object consStringFilter(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 MethodType handleType = handle.type();
final int paramCount = handleType.parameterCount();
assert fromType.parameterCount() == handleType.parameterCount();
MethodType newFromType = fromType;
MethodHandle[] filters = null;
for(int i = 0; i < paramCount; ++i) {
final MethodHandle filter = argConversionFilter(handleType.parameterType(i), fromType.parameterType(i));
if (filter != null) {
if (filters == null) {
filters = new MethodHandle[paramCount];
}
// "erase" specific type with Object type or else we'll get filter mismatch
newFromType = newFromType.changeParameterType(i, Object.class);
filters[i] = filter;
}
}
final MethodHandle typed = linkerServices.asType(handle, newFromType);
MethodHandle result = filters != null ? MethodHandles.filterArguments(typed, 0, filters) : typed;
// Filter Object typed return value for possible ScriptObjectMirror. We convert
// ScriptObjectMirror as ScriptObject (if it is mirror from current global).
if (MIRROR_ALWAYS && areBothObjects(handleType.returnType(), fromType.returnType())) {
result = MethodHandles.filterReturnValue(result, IMPORT_RESULT);
}
return result;
}
private static MethodHandle argConversionFilter(final Class<?> handleType, final Class<?> fromType) {
if (handleType == Object.class) {
if (fromType == Object.class) {
return EXPORT_ARGUMENT;
} else if (fromType == NativeArray.class) {
return EXPORT_NATIVE_ARRAY;
} else if (fromType == ScriptObject.class) {
return EXPORT_SCRIPT_OBJECT;
}
}
return null;
}
private static boolean areBothObjects(final Class<?> handleType, final Class<?> fromType) {
return handleType == Object.class && fromType == Object.class;
}
@Override
public MethodHandle asTypeLosslessReturn(final MethodHandle handle, final MethodType fromType) {
return Implementation.asTypeLosslessReturn(this, handle, fromType);
}
@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) {
if (sourceType == ConsString.class) {
if (String.class == targetType1 || CharSequence.class == targetType1) {
return Comparison.TYPE_1_BETTER;
}
if (String.class == targetType2 || CharSequence.class == targetType2) {
return Comparison.TYPE_2_BETTER;
}
}
return linkerServices.compareConversion(sourceType, targetType1, targetType2);
}
}
}
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