Source/JavaScriptCore/API/APICallbackFunction.h

/*
 * Copyright (C) 2013-2020 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 */

#ifndef APICallbackFunction_h
#define APICallbackFunction_h

#include "APICast.h"
#include "Error.h"
#include "JSCallbackConstructor.h"
#include "JSLock.h"
#include <wtf/Vector.h>

namespace JSC {

struct APICallbackFunction {
    template <typename T> static EncodedJSValue callImpl(JSGlobalObject*, CallFrame*);
    template <typename T> static EncodedJSValue constructImpl(JSGlobalObject*, CallFrame*);
};

template <typename T>
EncodedJSValue APICallbackFunction::callImpl(JSGlobalObject* globalObject, CallFrame* callFrame)
{
    VM& vm = getVM(globalObject);
    auto scope = DECLARE_THROW_SCOPE(vm);
    JSContextRef execRef = toRef(globalObject);
    JSObjectRef functionRef = toRef(callFrame->jsCallee());
    JSObjectRef thisObjRef = toRef(jsCast<JSObject*>(callFrame->thisValue().toThis(globalObject, ECMAMode::sloppy())));

    int argumentCount = static_cast<int>(callFrame->argumentCount());
    Vector<JSValueRef, 16> arguments;
    arguments.reserveInitialCapacity(argumentCount);
    for (int i = 0; i < argumentCount; i++)
        arguments.uncheckedAppend(toRef(globalObject, callFrame->uncheckedArgument(i)));

    JSValueRef exception = nullptr;
    JSValueRef result;
    {
        JSLock::DropAllLocks dropAllLocks(globalObject);
        result = jsCast<T*>(toJS(functionRef))->functionCallback()(execRef, functionRef, thisObjRef, argumentCount, arguments.data(), &exception);
    }
    if (exception) {
        throwException(globalObject, scope, toJS(globalObject, exception));
        return JSValue::encode(jsUndefined());
    }

    // result must be a valid JSValue.
    if (!result)
        return JSValue::encode(jsUndefined());

    return JSValue::encode(toJS(globalObject, result));
}

template <typename T>
EncodedJSValue APICallbackFunction::constructImpl(JSGlobalObject* globalObject, CallFrame* callFrame)
{
    VM& vm = getVM(globalObject);
    auto scope = DECLARE_THROW_SCOPE(vm);
    JSValue callee = callFrame->jsCallee();
    T* constructor = jsCast<T*>(callFrame->jsCallee());
    JSContextRef ctx = toRef(globalObject);
    JSObjectRef constructorRef = toRef(constructor);

    JSObjectCallAsConstructorCallback callback = constructor->constructCallback();
    if (callback) {
        JSValue prototype;
        JSValue newTarget = callFrame->newTarget();
        // If we are doing a derived class construction get the .prototype property off the new target first so we behave closer to normal JS.
        if (newTarget != constructor) {
            prototype = newTarget.get(globalObject, vm.propertyNames->prototype);
            RETURN_IF_EXCEPTION(scope, { });
        }

        size_t argumentCount = callFrame->argumentCount();
        Vector<JSValueRef, 16> arguments;
        arguments.reserveInitialCapacity(argumentCount);
        for (size_t i = 0; i < argumentCount; ++i)
            arguments.uncheckedAppend(toRef(globalObject, callFrame->uncheckedArgument(i)));

        JSValueRef exception = nullptr;
        JSObjectRef result;
        {
            JSLock::DropAllLocks dropAllLocks(globalObject);
            result = callback(ctx, constructorRef, argumentCount, arguments.data(), &exception);
        }

        if (exception) {
            throwException(globalObject, scope, toJS(globalObject, exception));
            return JSValue::encode(jsUndefined());
        }
        // result must be a valid JSValue.
        if (!result)
            return throwVMTypeError(globalObject, scope);

        JSObject* newObject = toJS(result);
        // This won't trigger proxy traps on newObject's prototype handler but that's probably desirable here anyway.
        if (newTarget != constructor && newObject->getPrototypeDirect() == constructor->get(globalObject, vm.propertyNames->prototype)) {
            RETURN_IF_EXCEPTION(scope, { });
            newObject->setPrototype(vm, globalObject, prototype);
            RETURN_IF_EXCEPTION(scope, { });
        }

        return JSValue::encode(newObject);
    }
    
    return JSValue::encode(toJS(JSObjectMake(ctx, jsCast<JSCallbackConstructor*>(callee)->classRef(), nullptr)));
}

} // namespace JSC

#endif // APICallbackFunction_h