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      1 /*
      2  * Copyright (C) 2010 Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #ifndef ScriptWrappable_h
     32 #define ScriptWrappable_h
     33 
     34 #include "bindings/v8/UnsafePersistent.h"
     35 #include "bindings/v8/V8Utilities.h"
     36 #include "bindings/v8/WrapperTypeInfo.h"
     37 #include <v8.h>
     38 
     39 // Helper to call webCoreInitializeScriptWrappableForInterface in the global namespace.
     40 template <class C> inline void initializeScriptWrappableHelper(C* object)
     41 {
     42     void webCoreInitializeScriptWrappableForInterface(C*);
     43     webCoreInitializeScriptWrappableForInterface(object);
     44 }
     45 
     46 namespace WebCore {
     47 
     48 class ScriptWrappable {
     49 public:
     50     ScriptWrappable() : m_wrapperOrTypeInfo(0) { }
     51 
     52     // Wrappables need to be initialized with their most derrived type for which
     53     // bindings exist, in much the same way that certain other types need to be
     54     // adopted and so forth. The overloaded initializeScriptWrappableForInterface()
     55     // functions are implemented by the generated V8 bindings code. Declaring the
     56     // extern function in the template avoids making a centralized header of all
     57     // the bindings in the universe. C++11's extern template feature may provide
     58     // a cleaner solution someday.
     59     template <class C> static void init(C* object)
     60     {
     61         initializeScriptWrappableHelper(object);
     62     }
     63 
     64     void setWrapper(v8::Handle<v8::Object> wrapper, v8::Isolate* isolate, const WrapperConfiguration& configuration)
     65     {
     66         ASSERT(!containsWrapper());
     67         if (!*wrapper) {
     68             m_wrapperOrTypeInfo = 0;
     69             return;
     70         }
     71         v8::Persistent<v8::Object> persistent(isolate, wrapper);
     72         configuration.configureWrapper(&persistent);
     73         persistent.SetWeak(this, &setWeakCallback);
     74         m_wrapperOrTypeInfo = reinterpret_cast<uintptr_t>(persistent.ClearAndLeak()) | 1;
     75         ASSERT(containsWrapper());
     76     }
     77 
     78     v8::Local<v8::Object> newLocalWrapper(v8::Isolate* isolate) const
     79     {
     80         return unsafePersistent().newLocal(isolate);
     81     }
     82 
     83     const WrapperTypeInfo* typeInfo()
     84     {
     85         if (containsTypeInfo())
     86             return reinterpret_cast<const WrapperTypeInfo*>(m_wrapperOrTypeInfo);
     87 
     88         if (containsWrapper())
     89             return toWrapperTypeInfo(*(unsafePersistent().persistent()));
     90 
     91         return 0;
     92     }
     93 
     94     void setTypeInfo(const WrapperTypeInfo* info)
     95     {
     96         m_wrapperOrTypeInfo = reinterpret_cast<uintptr_t>(info);
     97         ASSERT(containsTypeInfo());
     98     }
     99 
    100     static bool wrapperCanBeStoredInObject(const void*) { return false; }
    101     static bool wrapperCanBeStoredInObject(const ScriptWrappable*) { return true; }
    102 
    103     static void setWrapperInObject(void*, v8::Handle<v8::Object>, v8::Isolate*, const WrapperConfiguration&)
    104     {
    105         ASSERT_NOT_REACHED();
    106     }
    107 
    108     static void setWrapperInObject(ScriptWrappable* object, v8::Handle<v8::Object> wrapper, v8::Isolate* isolate, const WrapperConfiguration& configuration)
    109     {
    110         object->setWrapper(wrapper, isolate, configuration);
    111     }
    112 
    113     static const WrapperTypeInfo* getTypeInfoFromObject(void* object)
    114     {
    115         ASSERT_NOT_REACHED();
    116         return 0;
    117     }
    118 
    119     static const WrapperTypeInfo* getTypeInfoFromObject(ScriptWrappable* object)
    120     {
    121         return object->typeInfo();
    122     }
    123 
    124     static void setTypeInfoInObject(void* object, const WrapperTypeInfo* info)
    125     {
    126         ASSERT_NOT_REACHED();
    127     }
    128 
    129     static void setTypeInfoInObject(ScriptWrappable* object, const WrapperTypeInfo* info)
    130     {
    131         object->setTypeInfo(info);
    132     }
    133 
    134     template<typename V8T, typename T>
    135     static bool setReturnValueWithSecurityCheck(v8::ReturnValue<v8::Value> returnValue, T* object)
    136     {
    137         return ScriptWrappable::getUnsafeWrapperFromObject(object).template setReturnValueWithSecurityCheck<V8T>(returnValue, object);
    138     }
    139 
    140     template<typename T>
    141     static bool setReturnValue(v8::ReturnValue<v8::Value> returnValue, T* object)
    142     {
    143         return ScriptWrappable::getUnsafeWrapperFromObject(object).setReturnValue(returnValue);
    144     }
    145 
    146 protected:
    147     ~ScriptWrappable()
    148     {
    149         ASSERT(m_wrapperOrTypeInfo);  // Assert initialization via init() even if not subsequently wrapped.
    150         m_wrapperOrTypeInfo = 0;      // Break UAF attempts to wrap.
    151     }
    152 
    153 private:
    154     // For calling unsafePersistent and getWrapperFromObject.
    155     friend class MinorGCWrapperVisitor;
    156     friend class DOMDataStore;
    157 
    158     UnsafePersistent<v8::Object> unsafePersistent() const
    159     {
    160         v8::Object* object = containsWrapper() ? reinterpret_cast<v8::Object*>(m_wrapperOrTypeInfo & ~1) : 0;
    161         return UnsafePersistent<v8::Object>(object);
    162     }
    163 
    164     static UnsafePersistent<v8::Object> getUnsafeWrapperFromObject(void*)
    165     {
    166         ASSERT_NOT_REACHED();
    167         return UnsafePersistent<v8::Object>();
    168     }
    169 
    170     static UnsafePersistent<v8::Object> getUnsafeWrapperFromObject(ScriptWrappable* object)
    171     {
    172         return object->unsafePersistent();
    173     }
    174 
    175     inline bool containsWrapper() const { return (m_wrapperOrTypeInfo & 1) == 1; }
    176     inline bool containsTypeInfo() const { return m_wrapperOrTypeInfo && (m_wrapperOrTypeInfo & 1) == 0; }
    177 
    178     inline void disposeWrapper(v8::Local<v8::Object> value, const WrapperTypeInfo* info)
    179     {
    180         ASSERT(containsWrapper());
    181         ASSERT(value == *unsafePersistent().persistent());
    182         unsafePersistent().dispose();
    183         setTypeInfo(info);
    184     }
    185 
    186     // If zero, then this contains nothing, otherwise:
    187     //   If the bottom bit it set, then this contains a pointer to a wrapper object in the remainging bits.
    188     //   If the bottom bit is clear, then this contains a pointer to the wrapper type info in the remaining bits.
    189     uintptr_t m_wrapperOrTypeInfo;
    190 
    191     static void setWeakCallback(const v8::WeakCallbackData<v8::Object, ScriptWrappable>& data)
    192     {
    193         ASSERT(*data.GetParameter()->unsafePersistent().persistent() == data.GetValue());
    194 
    195         // Note: |object| might not be equal to |data|.GetParameter(), e.g., if ScriptWrappable isn't a left-most base class.
    196         void* object = toNative(data.GetValue());
    197         const WrapperTypeInfo* info = toWrapperTypeInfo(data.GetValue());
    198         ASSERT(info->derefObjectFunction);
    199 
    200         data.GetParameter()->disposeWrapper(data.GetValue(), info);
    201         // FIXME: I noticed that 50%~ of minor GC cycle times can be consumed
    202         // inside data.GetParameter()->deref(), which causes Node destructions. We should
    203         // make Node destructions incremental.
    204         info->derefObject(object);
    205     }
    206 };
    207 
    208 } // namespace WebCore
    209 
    210 #endif // ScriptWrappable_h
    211