JSPopStateEventCustom.cpp   [plain text]


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#include "config.h"
#include "JSPopStateEvent.h"

#include "DOMWrapperWorld.h"
#include "JSHistory.h"
#include <heap/HeapInlines.h>
#include <runtime/JSCJSValueInlines.h>

using namespace JSC;

namespace WebCore {

// Save the state value to the m_state member of a JSPopStateEvent, and return it, for convenience.
static const JSValue& cacheState(ExecState& state, const JSPopStateEvent* event, const JSValue& eventState)
{
    event->m_state.set(state.vm(), event, eventState);
    return eventState;
}

JSValue JSPopStateEvent::state(ExecState& state) const
{
    JSValue cachedValue = m_state.get();
    if (!cachedValue.isEmpty()) {
        // We cannot use a cached object if we are in a different world than the one it was created in.
        if (!cachedValue.isObject() || &worldForDOMObject(cachedValue.getObject()) == &currentWorld(&state))
            return cachedValue;
        ASSERT_NOT_REACHED();
    }

    PopStateEvent& event = wrapped();

    if (auto eventState = event.state()) {
        // We need to make sure a PopStateEvent does not leak objects in its state property across isolated DOM worlds.
        // Ideally, we would check that the worlds have different privileges but that's not possible yet.
        if (eventState.isObject() && &worldForDOMObject(eventState.getObject()) != &currentWorld(&state)) {
            if (auto serializedValue = event.trySerializeState(state))
                eventState = serializedValue->deserialize(state, globalObject());
            else
                eventState = jsNull();
        }
        return cacheState(state, this, eventState);
    }
    
    History* history = event.history();
    if (!history || !event.serializedState())
        return cacheState(state, this, jsNull());

    // There's no cached value from a previous invocation, nor a state value was provided by the
    // event, but there is a history object, so first we need to see if the state object has been
    // deserialized through the history object already.
    // The current history state object might've changed in the meantime, so we need to take care
    // of using the correct one, and always share the same deserialization with history.state.

    bool isSameState = history->isSameAsCurrentState(event.serializedState());
    JSValue result;

    if (isSameState) {
        JSHistory* jsHistory = jsCast<JSHistory*>(toJS(&state, globalObject(), *history).asCell());
        result = jsHistory->state(state);
    } else
        result = event.serializedState()->deserialize(state, globalObject());

    return cacheState(state, this, result);
}

} // namespace WebCore