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      1 /*
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      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
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      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
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     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
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     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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     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/v8/V8AbstractEventListener.h"
     33 
     34 #include "V8Event.h"
     35 #include "V8EventTarget.h"
     36 #include "bindings/v8/DateExtension.h"
     37 #include "bindings/v8/V8Binding.h"
     38 #include "bindings/v8/V8EventListenerList.h"
     39 #include "bindings/v8/V8HiddenPropertyName.h"
     40 #include "core/dom/Document.h"
     41 #include "core/dom/Event.h"
     42 #include "core/dom/EventNames.h"
     43 #include "core/inspector/InspectorCounters.h"
     44 #include "core/page/Frame.h"
     45 #include "core/workers/WorkerGlobalScope.h"
     46 
     47 namespace WebCore {
     48 
     49 V8AbstractEventListener::V8AbstractEventListener(bool isAttribute, PassRefPtr<DOMWrapperWorld> world, v8::Isolate* isolate)
     50     : EventListener(JSEventListenerType)
     51     , m_isAttribute(isAttribute)
     52     , m_world(world)
     53     , m_isolate(isolate)
     54 {
     55     ThreadLocalInspectorCounters::current().incrementCounter(ThreadLocalInspectorCounters::JSEventListenerCounter);
     56 }
     57 
     58 V8AbstractEventListener::~V8AbstractEventListener()
     59 {
     60     if (!m_listener.isEmpty()) {
     61         v8::HandleScope scope(m_isolate);
     62         V8EventListenerList::clearWrapper(m_listener.newLocal(m_isolate), m_isAttribute);
     63     }
     64     ThreadLocalInspectorCounters::current().decrementCounter(ThreadLocalInspectorCounters::JSEventListenerCounter);
     65 }
     66 
     67 void V8AbstractEventListener::handleEvent(ScriptExecutionContext* context, Event* event)
     68 {
     69     // Don't reenter V8 if execution was terminated in this instance of V8.
     70     if (context->isJSExecutionForbidden())
     71         return;
     72 
     73     ASSERT(event);
     74 
     75     // The callback function on XMLHttpRequest can clear the event listener and destroys 'this' object. Keep a local reference to it.
     76     // See issue 889829.
     77     RefPtr<V8AbstractEventListener> protect(this);
     78 
     79     v8::HandleScope handleScope(m_isolate);
     80 
     81     v8::Local<v8::Context> v8Context = toV8Context(context, world());
     82     if (v8Context.IsEmpty())
     83         return;
     84 
     85     // Enter the V8 context in which to perform the event handling.
     86     v8::Context::Scope scope(v8Context);
     87 
     88     // Get the V8 wrapper for the event object.
     89     v8::Isolate* isolate = v8Context->GetIsolate();
     90     v8::Handle<v8::Value> jsEvent = toV8(event, v8::Handle<v8::Object>(), isolate);
     91     if (jsEvent.IsEmpty())
     92         return;
     93     invokeEventHandler(context, event, v8::Local<v8::Value>::New(isolate, jsEvent));
     94 }
     95 
     96 void V8AbstractEventListener::setListenerObject(v8::Handle<v8::Object> listener)
     97 {
     98     m_listener.set(m_isolate, listener);
     99     m_listener.makeWeak(this, &makeWeakCallback);
    100 }
    101 
    102 void V8AbstractEventListener::invokeEventHandler(ScriptExecutionContext* context, Event* event, v8::Local<v8::Value> jsEvent)
    103 {
    104     // If jsEvent is empty, attempt to set it as a hidden value would crash v8.
    105     if (jsEvent.IsEmpty())
    106         return;
    107 
    108     v8::Local<v8::Context> v8Context = toV8Context(context, world());
    109     if (v8Context.IsEmpty())
    110         return;
    111 
    112     // We push the event being processed into the global object, so that it can be exposed by DOMWindow's bindings.
    113     v8::Handle<v8::String> eventSymbol = V8HiddenPropertyName::event();
    114     v8::Local<v8::Value> returnValue;
    115 
    116     // In beforeunload/unload handlers, we want to avoid sleeps which do tight loops of calling Date.getTime().
    117     if (event->type() == eventNames().beforeunloadEvent || event->type() == eventNames().unloadEvent)
    118         DateExtension::get()->setAllowSleep(false, v8Context->GetIsolate());
    119 
    120     {
    121         // Catch exceptions thrown in the event handler so they do not propagate to javascript code that caused the event to fire.
    122         v8::TryCatch tryCatch;
    123         tryCatch.SetVerbose(true);
    124 
    125         // Save the old 'event' property so we can restore it later.
    126         v8::Local<v8::Value> savedEvent = v8Context->Global()->GetHiddenValue(eventSymbol);
    127         tryCatch.Reset();
    128 
    129         // Make the event available in the global object, so DOMWindow can expose it.
    130         v8Context->Global()->SetHiddenValue(eventSymbol, jsEvent);
    131         tryCatch.Reset();
    132 
    133         returnValue = callListenerFunction(context, jsEvent, event);
    134         if (tryCatch.HasCaught())
    135             event->target()->uncaughtExceptionInEventHandler();
    136 
    137         if (!tryCatch.CanContinue()) { // Result of TerminateExecution().
    138             if (context->isWorkerGlobalScope())
    139                 toWorkerGlobalScope(context)->script()->forbidExecution();
    140             return;
    141         }
    142         tryCatch.Reset();
    143 
    144         // Restore the old event. This must be done for all exit paths through this method.
    145         if (savedEvent.IsEmpty())
    146             v8Context->Global()->SetHiddenValue(eventSymbol, v8::Undefined());
    147         else
    148             v8Context->Global()->SetHiddenValue(eventSymbol, savedEvent);
    149         tryCatch.Reset();
    150     }
    151 
    152     if (event->type() == eventNames().beforeunloadEvent || event->type() == eventNames().unloadEvent)
    153         DateExtension::get()->setAllowSleep(true, v8Context->GetIsolate());
    154 
    155     ASSERT(!handleOutOfMemory() || returnValue.IsEmpty());
    156 
    157     if (returnValue.IsEmpty())
    158         return;
    159 
    160     if (!returnValue->IsNull() && !returnValue->IsUndefined() && event->storesResultAsString())
    161         event->storeResult(toWebCoreString(returnValue));
    162 
    163     if (m_isAttribute && shouldPreventDefault(returnValue))
    164         event->preventDefault();
    165 }
    166 
    167 bool V8AbstractEventListener::shouldPreventDefault(v8::Local<v8::Value> returnValue)
    168 {
    169     // Prevent default action if the return value is false in accord with the spec
    170     // http://www.w3.org/TR/html5/webappapis.html#event-handler-attributes
    171     return returnValue->IsBoolean() && !returnValue->BooleanValue();
    172 }
    173 
    174 v8::Local<v8::Object> V8AbstractEventListener::getReceiverObject(ScriptExecutionContext* context, Event* event)
    175 {
    176     v8::Isolate* isolate = toV8Context(context, world())->GetIsolate();
    177     v8::Local<v8::Object> listener = m_listener.newLocal(isolate);
    178     if (!m_listener.isEmpty() && !listener->IsFunction())
    179         return listener;
    180 
    181     EventTarget* target = event->currentTarget();
    182     v8::Handle<v8::Value> value = toV8(target, v8::Handle<v8::Object>(), isolate);
    183     if (value.IsEmpty())
    184         return v8::Local<v8::Object>();
    185     return v8::Local<v8::Object>::New(v8::Handle<v8::Object>::Cast(value));
    186 }
    187 
    188 void V8AbstractEventListener::makeWeakCallback(v8::Isolate*, v8::Persistent<v8::Object>*, V8AbstractEventListener* listener)
    189 {
    190     listener->m_listener.clear();
    191 }
    192 
    193 } // namespace WebCore
    194