1 /*

     2  * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 

    26 package jdk.nashorn.internal.runtime.linker;

    27 

    28 import java.lang.invoke.MethodHandle;

    29 import java.lang.invoke.MethodHandles;

    30 import java.lang.invoke.MethodType;

    31 import jdk.internal.dynalink.beans.BeansLinker;

    32 import jdk.internal.dynalink.linker.ConversionComparator.Comparison;

    33 import jdk.internal.dynalink.linker.GuardedInvocation;

    34 import jdk.internal.dynalink.linker.GuardingDynamicLinker;

    35 import jdk.internal.dynalink.linker.LinkRequest;

    36 import jdk.internal.dynalink.linker.LinkerServices;

    37 import jdk.internal.dynalink.support.Lookup;

    38 import jdk.nashorn.internal.runtime.ConsString;

    39 

    40 /**

    41  * This linker delegates to a {@code BeansLinker} but passes it a special linker services object that has a modified

    42  * {@code asType} method that will ensure that we never pass internal engine objects that should not be externally

    43  * observable (currently only ConsString) to Java APIs, but rather that we flatten it into a String. We can't just add

    44  * this functionality as custom converters via {@code GuaardingTypeConverterFactory}, since they are not consulted when

    45  * the target method handle parameter signature is {@code Object}.

    46  */

    47 public class NashornBeansLinker implements GuardingDynamicLinker {

    48     private static final MethodHandle EXPORT_ARGUMENT = new Lookup(MethodHandles.lookup()).findOwnStatic("exportArgument", Object.class, Object.class);

    49 

    50     private final BeansLinker beansLinker = new BeansLinker();

    51 

    52     @Override

    53     public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest, final LinkerServices linkerServices) throws Exception {

    54         return getGuardedInvocation(beansLinker, linkRequest, linkerServices);

    55     }

    56 

    57     /**

    58      * Delegates to the specified linker but injects its linker services wrapper so that it will apply all special

    59      * conversions that this class does.

    60      * @param delegateLinker the linker to which the actual work is delegated to.

    61      * @param linkRequest the delegated link request

    62      * @param linkerServices the original link services that will be augmented with special conversions

    63      * @return the guarded invocation from the delegate, possibly augmented with special conversions

    64      * @throws Exception if the delegate throws an exception

    65      */

    66     public static GuardedInvocation getGuardedInvocation(final GuardingDynamicLinker delegateLinker, final LinkRequest linkRequest, final LinkerServices linkerServices) throws Exception {

    67         return delegateLinker.getGuardedInvocation(linkRequest, new NashornBeansLinkerServices(linkerServices));

    68     }

    69 

    70     static Object exportArgument(final Object arg) {

    71         return arg instanceof ConsString ? arg.toString() : arg;

    72     }

    73 

    74     private static class NashornBeansLinkerServices implements LinkerServices {

    75         private final LinkerServices linkerServices;

    76 

    77         NashornBeansLinkerServices(final LinkerServices linkerServices) {

    78             this.linkerServices = linkerServices;

    79         }

    80 

    81         @Override

    82         public MethodHandle asType(final MethodHandle handle, final MethodType fromType) {

    83             final MethodHandle typed = linkerServices.asType(handle, fromType);

    84 

    85             final MethodType handleType = handle.type();

    86             final int paramCount = handleType.parameterCount();

    87             assert fromType.parameterCount() == handleType.parameterCount();

    88 

    89             MethodHandle[] filters = null;

    90             for(int i = 0; i < paramCount; ++i) {

    91                 if(shouldConvert(handleType.parameterType(i), fromType.parameterType(i))) {

    92                     if(filters == null) {

    93                         filters = new MethodHandle[paramCount];

    94                     }

    95                     filters[i] = EXPORT_ARGUMENT;

    96                 }

    97             }

    98 

    99             return filters != null ? MethodHandles.filterArguments(typed, 0, filters) : typed;

   100         }

   101 

   102         @Override

   103         public MethodHandle asTypeLosslessReturn(final MethodHandle handle, final MethodType fromType) {

   104             return Implementation.asTypeLosslessReturn(this, handle, fromType);

   105         }

   106 

   107         private static boolean shouldConvert(final Class<?> handleType, final Class<?> fromType) {

   108             return handleType == Object.class && fromType == Object.class;

   109         }

   110 

   111         @Override

   112         public MethodHandle getTypeConverter(final Class<?> sourceType, final Class<?> targetType) {

   113             return linkerServices.getTypeConverter(sourceType, targetType);

   114         }

   115 

   116         @Override

   117         public boolean canConvert(final Class<?> from, final Class<?> to) {

   118             return linkerServices.canConvert(from, to);

   119         }

   120 

   121         @Override

   122         public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest) throws Exception {

   123             return linkerServices.getGuardedInvocation(linkRequest);

   124         }

   125 

   126         @Override

   127         public Comparison compareConversion(final Class<?> sourceType, final Class<?> targetType1, final Class<?> targetType2) {

   128             return linkerServices.compareConversion(sourceType, targetType1, targetType2);

   129         }

   130     }

   131 }