1 /*
   2  * Copyright (c) 2014, 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 static jdk.nashorn.internal.runtime.linker.BrowserJSObjectLinker.JSObjectHandles.JSOBJECT_GETMEMBER;
  29 import static jdk.nashorn.internal.runtime.linker.BrowserJSObjectLinker.JSObjectHandles.JSOBJECT_GETSLOT;
  30 import static jdk.nashorn.internal.runtime.linker.BrowserJSObjectLinker.JSObjectHandles.JSOBJECT_SETMEMBER;
  31 import static jdk.nashorn.internal.runtime.linker.BrowserJSObjectLinker.JSObjectHandles.JSOBJECT_SETSLOT;
  32 import java.lang.invoke.MethodHandle;
  33 import java.lang.invoke.MethodHandles;
  34 import jdk.internal.dynalink.CallSiteDescriptor;
  35 import jdk.internal.dynalink.linker.GuardedInvocation;
  36 import jdk.internal.dynalink.linker.LinkRequest;
  37 import jdk.internal.dynalink.linker.LinkerServices;
  38 import jdk.internal.dynalink.linker.TypeBasedGuardingDynamicLinker;
  39 import jdk.internal.dynalink.support.CallSiteDescriptorFactory;
  40 import jdk.nashorn.internal.lookup.MethodHandleFactory;
  41 import jdk.nashorn.internal.lookup.MethodHandleFunctionality;
  42 import jdk.nashorn.internal.runtime.JSType;
  43 
  44 /**
  45  * A Dynalink linker to handle web browser built-in JS (DOM etc.) objects.
  46  */
  47 final class BrowserJSObjectLinker implements TypeBasedGuardingDynamicLinker {
  48     private static ClassLoader extLoader;
  49     static {
  50         extLoader = BrowserJSObjectLinker.class.getClassLoader();
  51         // in case nashorn is loaded as bootstrap!
  52         if (extLoader == null) {
  53             extLoader = ClassLoader.getSystemClassLoader().getParent();
  54         }
  55     }
  56  
  57     private static final String JSOBJECT_CLASS = "netscape.javascript.JSObject";
  58     // not final because this is lazily initialized
  59     // when we hit a subclass for the first time.
  60     private static volatile Class<?> jsObjectClass;
  61     private final NashornBeansLinker nashornBeansLinker;
  62 
  63     BrowserJSObjectLinker(final NashornBeansLinker nashornBeansLinker) {
  64         this.nashornBeansLinker = nashornBeansLinker;
  65     }
  66 
  67     @Override
  68     public boolean canLinkType(final Class<?> type) {
  69         return canLinkTypeStatic(type);
  70     }
  71 
  72     static boolean canLinkTypeStatic(final Class<?> type) {
  73         if (jsObjectClass != null && jsObjectClass.isAssignableFrom(type)) {
  74             return true;
  75         }
  76 
  77         // check if this class is a subclass of JSObject
  78         Class<?> clazz = type;
  79         while (clazz != null) {
  80             if (clazz.getClassLoader() == extLoader &&
  81                 clazz.getName().equals(JSOBJECT_CLASS)) {
  82                 jsObjectClass = clazz;
  83                 return true;
  84             }
  85             clazz = clazz.getSuperclass();
  86         }
  87 
  88         return false;
  89     }
  90 
  91     private static void checkJSObjectClass() {
  92         assert jsObjectClass != null : JSOBJECT_CLASS + " not found!";
  93     }
  94 
  95     @Override
  96     public GuardedInvocation getGuardedInvocation(final LinkRequest request, final LinkerServices linkerServices) throws Exception {
  97         final LinkRequest requestWithoutContext = request.withoutRuntimeContext(); // Nashorn has no runtime context
  98         final Object self = requestWithoutContext.getReceiver();
  99         final CallSiteDescriptor desc = requestWithoutContext.getCallSiteDescriptor();
 100         checkJSObjectClass();
 101 
 102         if (desc.getNameTokenCount() < 2 || !"dyn".equals(desc.getNameToken(CallSiteDescriptor.SCHEME))) {
 103             // We only support standard "dyn:*[:*]" operations
 104             return null;
 105         }
 106 
 107         final GuardedInvocation inv;
 108         if (jsObjectClass.isInstance(self)) {
 109             inv = lookup(desc, request, linkerServices);
 110         } else {
 111             throw new AssertionError(); // Should never reach here.
 112         }
 113 
 114         return Bootstrap.asTypeSafeReturn(inv, linkerServices, desc);
 115     }
 116 
 117     private GuardedInvocation lookup(final CallSiteDescriptor desc, final LinkRequest request, final LinkerServices linkerServices) throws Exception {
 118         final String operator = CallSiteDescriptorFactory.tokenizeOperators(desc).get(0);
 119         final int c = desc.getNameTokenCount();
 120 
 121         switch (operator) {
 122             case "getProp":
 123             case "getElem":
 124             case "getMethod":
 125                 if (c > 2) {
 126                     return findGetMethod(desc);
 127                 }
 128             // For indexed get, we want GuardedInvocation from beans linker and pass it.
 129             // BrowserJSObjectLinker.get uses this fallback getter for explicit signature method access.
 130             return findGetIndexMethod(nashornBeansLinker.getGuardedInvocation(request, linkerServices));
 131             case "setProp":
 132             case "setElem":
 133                 return c > 2 ? findSetMethod(desc) : findSetIndexMethod();
 134             default:
 135                 return null;
 136         }
 137     }
 138 
 139     private static GuardedInvocation findGetMethod(final CallSiteDescriptor desc) {
 140         final String name = desc.getNameToken(CallSiteDescriptor.NAME_OPERAND);
 141         final MethodHandle getter = MH.insertArguments(JSOBJECT_GETMEMBER, 1, name);
 142         return new GuardedInvocation(getter, IS_JSOBJECT_GUARD);
 143     }
 144 
 145     private static GuardedInvocation findGetIndexMethod(final GuardedInvocation inv) {
 146         final MethodHandle getter = MH.insertArguments(JSOBJECTLINKER_GET, 0, inv.getInvocation());
 147         return inv.replaceMethods(getter, inv.getGuard());
 148     }
 149 
 150     private static GuardedInvocation findSetMethod(final CallSiteDescriptor desc) {
 151         final MethodHandle getter = MH.insertArguments(JSOBJECT_SETMEMBER, 1, desc.getNameToken(2));
 152         return new GuardedInvocation(getter, IS_JSOBJECT_GUARD);
 153     }
 154 
 155     private static GuardedInvocation findSetIndexMethod() {
 156         return new GuardedInvocation(JSOBJECTLINKER_PUT, IS_JSOBJECT_GUARD);
 157     }
 158 
 159     @SuppressWarnings("unused")
 160     private static boolean isJSObject(final Object self) {
 161         return jsObjectClass.isInstance(self);
 162     }
 163 
 164     @SuppressWarnings("unused")
 165     private static Object get(final MethodHandle fallback, final Object jsobj, final Object key) throws Throwable {
 166         if (key instanceof Integer) {
 167             return JSOBJECT_GETSLOT.invokeExact(jsobj, (int)key);
 168         } else if (key instanceof Number) {
 169             final int index = getIndex((Number)key);
 170             if (index > -1) {
 171                 return JSOBJECT_GETSLOT.invokeExact(jsobj, index);
 172             }
 173         } else if (key instanceof String) {
 174             final String name = (String)key;
 175             if (name.indexOf('(') != -1) {
 176                 return fallback.invokeExact(jsobj, key);
 177             }
 178             return JSOBJECT_GETMEMBER.invokeExact(jsobj, (String)key);
 179         }
 180         return null;
 181     }
 182 
 183     @SuppressWarnings("unused")
 184     private static void put(final Object jsobj, final Object key, final Object value) throws Throwable {
 185         if (key instanceof Integer) {
 186             JSOBJECT_SETSLOT.invokeExact(jsobj, (int)key, value);
 187         } else if (key instanceof Number) {
 188             JSOBJECT_SETSLOT.invokeExact(jsobj, getIndex((Number)key), value);
 189         } else if (key instanceof String) {
 190             JSOBJECT_SETMEMBER.invokeExact(jsobj, (String)key, value);
 191         }
 192     }
 193 
 194     private static int getIndex(final Number n) {
 195         final double value = n.doubleValue();
 196         return JSType.isRepresentableAsInt(value) ? (int)value : -1;
 197     }
 198 
 199     private static final MethodHandleFunctionality MH = MethodHandleFactory.getFunctionality();
 200     // method handles of the current class
 201     private static final MethodHandle IS_JSOBJECT_GUARD  = findOwnMH_S("isJSObject", boolean.class, Object.class);
 202     private static final MethodHandle JSOBJECTLINKER_GET = findOwnMH_S("get", Object.class, MethodHandle.class, Object.class, Object.class);
 203     private static final MethodHandle JSOBJECTLINKER_PUT = findOwnMH_S("put", Void.TYPE, Object.class, Object.class, Object.class);
 204 
 205     private static MethodHandle findOwnMH_S(final String name, final Class<?> rtype, final Class<?>... types) {
 206             return MH.findStatic(MethodHandles.lookup(), BrowserJSObjectLinker.class, name, MH.type(rtype, types));
 207     }
 208 
 209     // method handles of netscape.javascript.JSObject class
 210     // These are in separate class as we lazily initialize these
 211     // method handles when we hit a subclass of JSObject first time.
 212     static class JSObjectHandles {
 213         // method handles of JSObject class
 214         static final MethodHandle JSOBJECT_GETMEMBER     = findJSObjectMH_V("getMember", Object.class, String.class).asType(MH.type(Object.class, Object.class, String.class));
 215         static final MethodHandle JSOBJECT_GETSLOT       = findJSObjectMH_V("getSlot", Object.class, int.class).asType(MH.type(Object.class, Object.class, int.class));
 216         static final MethodHandle JSOBJECT_SETMEMBER     = findJSObjectMH_V("setMember", Void.TYPE, String.class, Object.class).asType(MH.type(Void.TYPE, Object.class, String.class, Object.class));
 217         static final MethodHandle JSOBJECT_SETSLOT       = findJSObjectMH_V("setSlot", Void.TYPE, int.class, Object.class).asType(MH.type(Void.TYPE, Object.class, int.class, Object.class));
 218 
 219         private static MethodHandle findJSObjectMH_V(final String name, final Class<?> rtype, final Class<?>... types) {
 220             checkJSObjectClass();
 221             return MH.findVirtual(MethodHandles.publicLookup(), jsObjectClass, name, MH.type(rtype, types));
 222         }
 223     }
 224 }
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