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      1 /*
      2  * Copyright (C) 2006, 2007, 2008, 2009 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 #include "config.h"
     32 #include "bindings/core/v8/V8AbstractEventListener.h"
     33 
     34 #include "bindings/core/v8/V8Binding.h"
     35 #include "bindings/core/v8/V8Event.h"
     36 #include "bindings/core/v8/V8EventListenerList.h"
     37 #include "bindings/core/v8/V8EventTarget.h"
     38 #include "bindings/core/v8/V8HiddenValue.h"
     39 #include "core/events/BeforeUnloadEvent.h"
     40 #include "core/events/Event.h"
     41 #include "core/inspector/InspectorCounters.h"
     42 #include "core/workers/WorkerGlobalScope.h"
     43 
     44 namespace blink {
     45 
     46 V8AbstractEventListener::V8AbstractEventListener(bool isAttribute, ScriptState* scriptState)
     47     : EventListener(JSEventListenerType)
     48     , m_isAttribute(isAttribute)
     49     , m_scriptState(scriptState)
     50     , m_isolate(scriptState->isolate())
     51 {
     52     if (isMainThread())
     53         InspectorCounters::incrementCounter(InspectorCounters::JSEventListenerCounter);
     54 }
     55 
     56 V8AbstractEventListener::V8AbstractEventListener(bool isAttribute, v8::Isolate* isolate)
     57     : EventListener(JSEventListenerType)
     58     , m_isAttribute(isAttribute)
     59     , m_scriptState(nullptr)
     60     , m_isolate(isolate)
     61 {
     62     if (isMainThread())
     63         InspectorCounters::incrementCounter(InspectorCounters::JSEventListenerCounter);
     64 }
     65 
     66 V8AbstractEventListener::~V8AbstractEventListener()
     67 {
     68     if (!m_listener.isEmpty()) {
     69         v8::HandleScope scope(m_isolate);
     70         V8EventListenerList::clearWrapper(m_listener.newLocal(isolate()), m_isAttribute, isolate());
     71     }
     72     if (isMainThread())
     73         InspectorCounters::decrementCounter(InspectorCounters::JSEventListenerCounter);
     74 }
     75 
     76 void V8AbstractEventListener::handleEvent(ExecutionContext*, Event* event)
     77 {
     78     if (scriptState()->contextIsValid())
     79         return;
     80     if (!scriptState()->executionContext())
     81         return;
     82     // Don't reenter V8 if execution was terminated in this instance of V8.
     83     if (scriptState()->executionContext()->isJSExecutionForbidden())
     84         return;
     85 
     86     ASSERT(event);
     87 
     88     // The callback function on XMLHttpRequest can clear the event listener and destroys 'this' object. Keep a local reference to it.
     89     // See issue 889829.
     90     RefPtr<V8AbstractEventListener> protect(this);
     91 
     92     ScriptState::Scope scope(scriptState());
     93 
     94     // Get the V8 wrapper for the event object.
     95     v8::Handle<v8::Value> jsEvent = toV8(event, scriptState()->context()->Global(), isolate());
     96     if (jsEvent.IsEmpty())
     97         return;
     98     invokeEventHandler(event, v8::Local<v8::Value>::New(isolate(), jsEvent));
     99 }
    100 
    101 void V8AbstractEventListener::setListenerObject(v8::Handle<v8::Object> listener)
    102 {
    103     m_listener.set(isolate(), listener);
    104     m_listener.setWeak(this, &setWeakCallback);
    105 }
    106 
    107 void V8AbstractEventListener::invokeEventHandler(Event* event, v8::Local<v8::Value> jsEvent)
    108 {
    109     // If jsEvent is empty, attempt to set it as a hidden value would crash v8.
    110     if (jsEvent.IsEmpty())
    111         return;
    112 
    113     ASSERT(!scriptState()->contextIsValid());
    114     v8::Local<v8::Value> returnValue;
    115     {
    116         // Catch exceptions thrown in the event handler so they do not propagate to javascript code that caused the event to fire.
    117         v8::TryCatch tryCatch;
    118         tryCatch.SetVerbose(true);
    119 
    120         // Save the old 'event' property so we can restore it later.
    121         v8::Local<v8::Value> savedEvent = V8HiddenValue::getHiddenValue(isolate(), scriptState()->context()->Global(), V8HiddenValue::event(isolate()));
    122         tryCatch.Reset();
    123 
    124         // Make the event available in the global object, so LocalDOMWindow can expose it.
    125         V8HiddenValue::setHiddenValue(isolate(), scriptState()->context()->Global(), V8HiddenValue::event(isolate()), jsEvent);
    126         tryCatch.Reset();
    127 
    128         returnValue = callListenerFunction(jsEvent, event);
    129         if (tryCatch.HasCaught())
    130             event->target()->uncaughtExceptionInEventHandler();
    131 
    132         if (!tryCatch.CanContinue()) { // Result of TerminateExecution().
    133             if (scriptState()->executionContext()->isWorkerGlobalScope())
    134                 toWorkerGlobalScope(scriptState()->executionContext())->script()->forbidExecution();
    135             return;
    136         }
    137         tryCatch.Reset();
    138 
    139         // Restore the old event. This must be done for all exit paths through this method.
    140         if (savedEvent.IsEmpty())
    141             V8HiddenValue::setHiddenValue(isolate(), scriptState()->context()->Global(), V8HiddenValue::event(isolate()), v8::Undefined(isolate()));
    142         else
    143             V8HiddenValue::setHiddenValue(isolate(), scriptState()->context()->Global(), V8HiddenValue::event(isolate()), savedEvent);
    144         tryCatch.Reset();
    145     }
    146 
    147     if (returnValue.IsEmpty())
    148         return;
    149 
    150     if (m_isAttribute && !returnValue->IsNull() && !returnValue->IsUndefined() && event->isBeforeUnloadEvent()) {
    151         TOSTRING_VOID(V8StringResource<>, stringReturnValue, returnValue);
    152         toBeforeUnloadEvent(event)->setReturnValue(stringReturnValue);
    153     }
    154 
    155     if (m_isAttribute && shouldPreventDefault(returnValue))
    156         event->preventDefault();
    157 }
    158 
    159 bool V8AbstractEventListener::shouldPreventDefault(v8::Local<v8::Value> returnValue)
    160 {
    161     // Prevent default action if the return value is false in accord with the spec
    162     // http://www.w3.org/TR/html5/webappapis.html#event-handler-attributes
    163     return returnValue->IsBoolean() && !returnValue->BooleanValue();
    164 }
    165 
    166 v8::Local<v8::Object> V8AbstractEventListener::getReceiverObject(Event* event)
    167 {
    168     v8::Local<v8::Object> listener = m_listener.newLocal(isolate());
    169     if (!m_listener.isEmpty() && !listener->IsFunction())
    170         return listener;
    171 
    172     EventTarget* target = event->currentTarget();
    173     v8::Handle<v8::Value> value = toV8(target, scriptState()->context()->Global(), isolate());
    174     if (value.IsEmpty())
    175         return v8::Local<v8::Object>();
    176     return v8::Local<v8::Object>::New(isolate(), v8::Handle<v8::Object>::Cast(value));
    177 }
    178 
    179 bool V8AbstractEventListener::belongsToTheCurrentWorld() const
    180 {
    181     return isolate()->InContext() && &world() == &DOMWrapperWorld::current(isolate());
    182 }
    183 
    184 void V8AbstractEventListener::setWeakCallback(const v8::WeakCallbackData<v8::Object, V8AbstractEventListener> &data)
    185 {
    186     data.GetParameter()->m_listener.clear();
    187 }
    188 
    189 } // namespace blink
    190