ScriptController.cpp   [plain text]

/*
 *  Copyright (C) 1999-2001 Harri Porten (porten@kde.org)
 *  Copyright (C) 2001 Peter Kelly (pmk@post.com)
 *  Copyright (C) 2006-2016 Apple Inc. All rights reserved.
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include "config.h"
#include "ScriptController.h"

#include "BridgeJSC.h"
#include "CachedModuleScript.h"
#include "CommonVM.h"
#include "ContentSecurityPolicy.h"
#include "DocumentLoader.h"
#include "Event.h"
#include "EventNames.h"
#include "Frame.h"
#include "FrameLoaderClient.h"
#include "GCController.h"
#include "HTMLPlugInElement.h"
#include "InspectorInstrumentation.h"
#include "JSDOMWindow.h"
#include "JSDocument.h"
#include "JSMainThreadExecState.h"
#include "MainFrame.h"
#include "MemoryPressureHandler.h"
#include "NP_jsobject.h"
#include "Page.h"
#include "PageConsoleClient.h"
#include "PageGroup.h"
#include "PluginViewBase.h"
#include "ScriptElement.h"
#include "ScriptSourceCode.h"
#include "ScriptableDocumentParser.h"
#include "Settings.h"
#include "UserGestureIndicator.h"
#include "WebCoreJSClientData.h"
#include "npruntime_impl.h"
#include "runtime_root.h"
#include <debugger/Debugger.h>
#include <heap/StrongInlines.h>
#include <inspector/ScriptCallStack.h>
#include <runtime/InitializeThreading.h>
#include <runtime/JSFunction.h>
#include <runtime/JSInternalPromise.h>
#include <runtime/JSLock.h>
#include <runtime/JSModuleRecord.h>
#include <runtime/JSNativeStdFunction.h>
#include <wtf/SetForScope.h>
#include <wtf/Threading.h>
#include <wtf/text/TextPosition.h>

using namespace JSC;

namespace WebCore {

static void collectGarbageAfterWindowShellDestruction()
{
    // Make sure to GC Extra Soon(tm) during memory pressure conditions
    // to soften high peaks of memory usage during navigation.
    if (MemoryPressureHandler::singleton().isUnderMemoryPressure()) {
        // NOTE: We do the collection on next runloop to ensure that there's no pointer
        //       to the window object on the stack.
        GCController::singleton().garbageCollectOnNextRunLoop();
    } else
        GCController::singleton().garbageCollectSoon();
}

void ScriptController::initializeThreading()
{
#if !PLATFORM(IOS)
    JSC::initializeThreading();
    WTF::initializeMainThread();
#endif
}

ScriptController::ScriptController(Frame& frame)
    : m_frame(frame)
    , m_sourceURL(0)
    , m_paused(false)
#if ENABLE(NETSCAPE_PLUGIN_API)
    , m_windowScriptNPObject(0)
#endif
#if PLATFORM(COCOA)
    , m_windowScriptObject(0)
#endif
{
}

ScriptController::~ScriptController()
{
    disconnectPlatformScriptObjects();

    if (m_cacheableBindingRootObject) {
        JSLockHolder lock(commonVM());
        m_cacheableBindingRootObject->invalidate();
        m_cacheableBindingRootObject = nullptr;
    }

    // It's likely that destroying m_windowShells will create a lot of garbage.
    if (!m_windowShells.isEmpty()) {
        while (!m_windowShells.isEmpty()) {
            ShellMap::iterator iter = m_windowShells.begin();
            iter->value->window()->setConsoleClient(nullptr);
            destroyWindowShell(*iter->key);
        }
        collectGarbageAfterWindowShellDestruction();
    }
}

void ScriptController::destroyWindowShell(DOMWrapperWorld& world)
{
    ASSERT(m_windowShells.contains(&world));
    m_windowShells.remove(&world);
    world.didDestroyWindowShell(this);
}

JSDOMWindowShell& ScriptController::createWindowShell(DOMWrapperWorld& world)
{
    ASSERT(!m_windowShells.contains(&world));

    VM& vm = world.vm();

    Structure* structure = JSDOMWindowShell::createStructure(vm, jsNull());
    Strong<JSDOMWindowShell> windowShell(vm, JSDOMWindowShell::create(vm, m_frame.document()->domWindow(), structure, world));
    Strong<JSDOMWindowShell> windowShell2(windowShell);
    m_windowShells.add(&world, windowShell);
    world.didCreateWindowShell(this);
    return *windowShell.get();
}

JSValue ScriptController::evaluateInWorld(const ScriptSourceCode& sourceCode, DOMWrapperWorld& world, ExceptionDetails* exceptionDetails)
{
    JSLockHolder lock(world.vm());

    const SourceCode& jsSourceCode = sourceCode.jsSourceCode();
    String sourceURL = jsSourceCode.provider()->url();

    // evaluate code. Returns the JS return value or 0
    // if there was none, an error occurred or the type couldn't be converted.

    // inlineCode is true for <a href="javascript:doSomething()">
    // and false for <script>doSomething()</script>. Check if it has the
    // expected value in all cases.
    // See smart window.open policy for where this is used.
    JSDOMWindowShell* shell = windowShell(world);
    ExecState* exec = shell->window()->globalExec();
    const String* savedSourceURL = m_sourceURL;
    m_sourceURL = &sourceURL;

    Ref<Frame> protector(m_frame);

    InspectorInstrumentationCookie cookie = InspectorInstrumentation::willEvaluateScript(m_frame, sourceURL, sourceCode.startLine());

    NakedPtr<JSC::Exception> evaluationException;
    JSValue returnValue = JSMainThreadExecState::profiledEvaluate(exec, JSC::ProfilingReason::Other, jsSourceCode, shell, evaluationException);

    InspectorInstrumentation::didEvaluateScript(cookie, m_frame);

    if (evaluationException) {
        reportException(exec, evaluationException, sourceCode.cachedScript(), exceptionDetails);
        m_sourceURL = savedSourceURL;
        return { };
    }

    m_sourceURL = savedSourceURL;
    return returnValue;
}

JSValue ScriptController::evaluate(const ScriptSourceCode& sourceCode, ExceptionDetails* exceptionDetails)
{
    return evaluateInWorld(sourceCode, mainThreadNormalWorld(), exceptionDetails);
}

void ScriptController::loadModuleScriptInWorld(CachedModuleScript& moduleScript, const String& moduleName, DOMWrapperWorld& world, Element& element)
{
    JSLockHolder lock(world.vm());

    auto& shell = *windowShell(world);
    auto& state = *shell.window()->globalExec();

    auto& promise = JSMainThreadExecState::loadModule(state, moduleName, toJS(&state, shell.window(), &element));
    setupModuleScriptHandlers(moduleScript, promise, world);
}

void ScriptController::loadModuleScript(CachedModuleScript& moduleScript, const String& moduleName, Element& element)
{
    loadModuleScriptInWorld(moduleScript, moduleName, mainThreadNormalWorld(), element);
}

void ScriptController::loadModuleScriptInWorld(CachedModuleScript& moduleScript, const ScriptSourceCode& sourceCode, DOMWrapperWorld& world, Element& element)
{
    JSLockHolder lock(world.vm());

    auto& shell = *windowShell(world);
    auto& state = *shell.window()->globalExec();

    auto& promise = JSMainThreadExecState::loadModule(state, sourceCode.jsSourceCode(), toJS(&state, shell.window(), &element));
    setupModuleScriptHandlers(moduleScript, promise, world);
}

void ScriptController::loadModuleScript(CachedModuleScript& moduleScript, const ScriptSourceCode& sourceCode, Element& element)
{
    loadModuleScriptInWorld(moduleScript, sourceCode, mainThreadNormalWorld(), element);
}

JSC::JSValue ScriptController::linkAndEvaluateModuleScriptInWorld(CachedModuleScript& moduleScript, DOMWrapperWorld& world, Element& element)
{
    JSLockHolder lock(world.vm());

    auto& shell = *windowShell(world);
    auto& state = *shell.window()->globalExec();

    // FIXME: Preventing Frame from being destroyed is essentially unnecessary.
    // https://bugs.webkit.org/show_bug.cgi?id=164763
    Ref<Frame> protector(m_frame);

    NakedPtr<JSC::Exception> evaluationException;
    auto returnValue = JSMainThreadExecState::linkAndEvaluateModule(state, Identifier::fromUid(&state.vm(), moduleScript.moduleKey()), toJS(&state, shell.window(), &element), evaluationException);
    if (evaluationException) {
        // FIXME: Give a chance to dump the stack trace if the "crossorigin" attribute allows.
        // https://bugs.webkit.org/show_bug.cgi?id=164539
        reportException(&state, evaluationException, nullptr);
        return jsUndefined();
    }
    return returnValue;
}

JSC::JSValue ScriptController::linkAndEvaluateModuleScript(CachedModuleScript& moduleScript, Element& element)
{
    return linkAndEvaluateModuleScriptInWorld(moduleScript, mainThreadNormalWorld(), element);
}

JSC::JSValue ScriptController::evaluateModule(const URL& sourceURL, JSModuleRecord& moduleRecord, DOMWrapperWorld& world)
{
    JSLockHolder lock(world.vm());

    const auto& jsSourceCode = moduleRecord.sourceCode();

    auto& shell = *windowShell(world);
    auto& state = *shell.window()->globalExec();
    SetForScope<const String*> sourceURLScope(m_sourceURL, &sourceURL.string());

    Ref<Frame> protector(m_frame);

    auto cookie = InspectorInstrumentation::willEvaluateScript(m_frame, sourceURL, jsSourceCode.firstLine().oneBasedInt());

    auto returnValue = moduleRecord.evaluate(&state);
    InspectorInstrumentation::didEvaluateScript(cookie, m_frame);

    return returnValue;
}

JSC::JSValue ScriptController::evaluateModule(const URL& sourceURL, JSModuleRecord& moduleRecord)
{
    return evaluateModule(sourceURL, moduleRecord, mainThreadNormalWorld());
}

Ref<DOMWrapperWorld> ScriptController::createWorld()
{
    return DOMWrapperWorld::create(commonVM());
}

Vector<JSC::Strong<JSDOMWindowShell>> ScriptController::windowShells()
{
    Vector<JSC::Strong<JSDOMWindowShell>> windowShells;
    copyValuesToVector(m_windowShells, windowShells);
    return windowShells;
}

void ScriptController::getAllWorlds(Vector<Ref<DOMWrapperWorld>>& worlds)
{
    static_cast<JSVMClientData*>(commonVM().clientData)->getAllWorlds(worlds);
}

void ScriptController::clearWindowShellsNotMatchingDOMWindow(DOMWindow* newDOMWindow, bool goingIntoPageCache)
{
    if (m_windowShells.isEmpty())
        return;

    JSLockHolder lock(commonVM());

    for (auto& windowShell : windowShells()) {
        if (&windowShell->window()->wrapped() == newDOMWindow)
            continue;

        // Clear the debugger and console from the current window before setting the new window.
        attachDebugger(windowShell.get(), nullptr);
        windowShell->window()->setConsoleClient(nullptr);
        windowShell->window()->willRemoveFromWindowShell();
    }

    // It's likely that resetting our windows created a lot of garbage, unless
    // it went in a back/forward cache.
    if (!goingIntoPageCache)
        collectGarbageAfterWindowShellDestruction();
}

void ScriptController::setDOMWindowForWindowShell(DOMWindow* newDOMWindow)
{
    if (m_windowShells.isEmpty())
        return;
    
    JSLockHolder lock(commonVM());
    
    for (auto& windowShell : windowShells()) {
        if (&windowShell->window()->wrapped() == newDOMWindow)
            continue;
        
        windowShell->setWindow(newDOMWindow);
        
        // An m_cacheableBindingRootObject persists between page navigations
        // so needs to know about the new JSDOMWindow.
        if (m_cacheableBindingRootObject)
            m_cacheableBindingRootObject->updateGlobalObject(windowShell->window());

        if (Page* page = m_frame.page()) {
            attachDebugger(windowShell.get(), page->debugger());
            windowShell->window()->setProfileGroup(page->group().identifier());
            windowShell->window()->setConsoleClient(&page->console());
        }
    }
}

JSDOMWindowShell* ScriptController::initScript(DOMWrapperWorld& world)
{
    ASSERT(!m_windowShells.contains(&world));

    JSLockHolder lock(world.vm());

    JSDOMWindowShell& windowShell = createWindowShell(world);

    windowShell.window()->updateDocument();

    if (Document* document = m_frame.document())
        document->contentSecurityPolicy()->didCreateWindowShell(windowShell);

    if (Page* page = m_frame.page()) {
        attachDebugger(&windowShell, page->debugger());
        windowShell.window()->setProfileGroup(page->group().identifier());
        windowShell.window()->setConsoleClient(&page->console());
    }

    m_frame.loader().dispatchDidClearWindowObjectInWorld(world);

    return &windowShell;
}

static Identifier jsValueToModuleKey(ExecState* exec, JSValue value)
{
    if (value.isSymbol())
        return Identifier::fromUid(jsCast<Symbol*>(value)->privateName());
    ASSERT(value.isString());
    return asString(value)->toIdentifier(exec);
}

void ScriptController::setupModuleScriptHandlers(CachedModuleScript& moduleScriptRef, JSInternalPromise& promise, DOMWrapperWorld& world)
{
    auto& shell = *windowShell(world);
    auto& state = *shell.window()->globalExec();

    // It is not guaranteed that either fulfillHandler or rejectHandler is eventually called.
    // For example, if the page load is canceled, the DeferredPromise used in the module loader pipeline will stop executing JS code.
    // Thus the promise returned from this function could remain unresolved.

    JSC::PrivateName moduleLoaderAlreadyReportedErrorSymbol = m_moduleLoaderAlreadyReportedErrorSymbol;
    JSC::PrivateName moduleLoaderFetchingIsCanceledSymbol = m_moduleLoaderFetchingIsCanceledSymbol;

    RefPtr<CachedModuleScript> moduleScript(&moduleScriptRef);

    auto& fulfillHandler = *JSNativeStdFunction::create(state.vm(), shell.window(), 1, String(), [moduleScript](ExecState* exec) {
        Identifier moduleKey = jsValueToModuleKey(exec, exec->argument(0));
        moduleScript->notifyLoadCompleted(*moduleKey.impl());
        return JSValue::encode(jsUndefined());
    });

    auto& rejectHandler = *JSNativeStdFunction::create(state.vm(), shell.window(), 1, String(), [moduleScript, moduleLoaderAlreadyReportedErrorSymbol, moduleLoaderFetchingIsCanceledSymbol](ExecState* exec) {
        JSValue error = exec->argument(0);
        if (auto* symbol = jsDynamicCast<Symbol*>(error)) {
            if (symbol->privateName() == moduleLoaderAlreadyReportedErrorSymbol) {
                moduleScript->notifyLoadFailed(LoadableScript::Error {
                    LoadableScript::ErrorType::CachedScript,
                    std::nullopt
                });
                return JSValue::encode(jsUndefined());
            }

            if (symbol->privateName() == moduleLoaderFetchingIsCanceledSymbol) {
                moduleScript->notifyLoadWasCanceled();
                return JSValue::encode(jsUndefined());
            }
        }

        VM& vm = exec->vm();
        auto scope = DECLARE_CATCH_SCOPE(vm);
        moduleScript->notifyLoadFailed(LoadableScript::Error {
            LoadableScript::ErrorType::CachedScript,
            LoadableScript::ConsoleMessage {
                MessageSource::JS,
                MessageLevel::Error,
                retrieveErrorMessage(*exec, vm, error, scope),
            }
        });
        return JSValue::encode(jsUndefined());
    });

    promise.then(&state, &fulfillHandler, &rejectHandler);
}

TextPosition ScriptController::eventHandlerPosition() const
{
    // FIXME: If we are not currently parsing, we should use our current location
    // in JavaScript, to cover cases like "element.setAttribute('click', ...)".

    // FIXME: This location maps to the end of the HTML tag, and not to the
    // exact column number belonging to the event handler attribute.
    ScriptableDocumentParser* parser = m_frame.document()->scriptableDocumentParser();
    if (parser)
        return parser->textPosition();
    return TextPosition();
}

void ScriptController::enableEval()
{
    JSDOMWindowShell* windowShell = existingWindowShell(mainThreadNormalWorld());
    if (!windowShell)
        return;
    windowShell->window()->setEvalEnabled(true);
}

void ScriptController::disableEval(const String& errorMessage)
{
    JSDOMWindowShell* windowShell = existingWindowShell(mainThreadNormalWorld());
    if (!windowShell)
        return;
    windowShell->window()->setEvalEnabled(false, errorMessage);
}

bool ScriptController::processingUserGesture()
{
    return UserGestureIndicator::processingUserGesture();
}

bool ScriptController::processingUserGestureForMedia()
{
    return UserGestureIndicator::processingUserGestureForMedia();
}

bool ScriptController::canAccessFromCurrentOrigin(Frame* frame)
{
    ExecState* state = JSMainThreadExecState::currentState();

    // If the current state is null we're in a call path where the DOM security check doesn't apply (eg. parser).
    if (!state)
        return true;

    return BindingSecurity::shouldAllowAccessToFrame(state, frame);
}

void ScriptController::attachDebugger(JSC::Debugger* debugger)
{
    Vector<JSC::Strong<JSDOMWindowShell>> windowShells = this->windowShells();
    for (size_t i = 0; i < windowShells.size(); ++i)
        attachDebugger(windowShells[i].get(), debugger);
}

void ScriptController::attachDebugger(JSDOMWindowShell* shell, JSC::Debugger* debugger)
{
    if (!shell)
        return;

    JSDOMWindow* globalObject = shell->window();
    JSLockHolder lock(globalObject->vm());
    if (debugger)
        debugger->attach(globalObject);
    else if (JSC::Debugger* currentDebugger = globalObject->debugger())
        currentDebugger->detach(globalObject, JSC::Debugger::TerminatingDebuggingSession);
}

void ScriptController::updateDocument()
{
    Vector<JSC::Strong<JSDOMWindowShell>> windowShells = this->windowShells();
    for (size_t i = 0; i < windowShells.size(); ++i) {
        JSDOMWindowShell* windowShell = windowShells[i].get();
        JSLockHolder lock(windowShell->world().vm());
        windowShell->window()->updateDocument();
    }
}

Bindings::RootObject* ScriptController::cacheableBindingRootObject()
{
    if (!canExecuteScripts(NotAboutToExecuteScript))
        return 0;

    if (!m_cacheableBindingRootObject) {
        JSLockHolder lock(commonVM());
        m_cacheableBindingRootObject = Bindings::RootObject::create(0, globalObject(pluginWorld()));
    }
    return m_cacheableBindingRootObject.get();
}

Bindings::RootObject* ScriptController::bindingRootObject()
{
    if (!canExecuteScripts(NotAboutToExecuteScript))
        return 0;

    if (!m_bindingRootObject) {
        JSLockHolder lock(commonVM());
        m_bindingRootObject = Bindings::RootObject::create(0, globalObject(pluginWorld()));
    }
    return m_bindingRootObject.get();
}

RefPtr<Bindings::RootObject> ScriptController::createRootObject(void* nativeHandle)
{
    RootObjectMap::iterator it = m_rootObjects.find(nativeHandle);
    if (it != m_rootObjects.end())
        return it->value;

    RefPtr<Bindings::RootObject> rootObject = Bindings::RootObject::create(nativeHandle, globalObject(pluginWorld()));

    m_rootObjects.set(nativeHandle, rootObject);
    return rootObject;
}

void ScriptController::collectIsolatedContexts(Vector<std::pair<JSC::ExecState*, SecurityOrigin*>>& result)
{
    for (ShellMap::iterator iter = m_windowShells.begin(); iter != m_windowShells.end(); ++iter) {
        JSC::ExecState* exec = iter->value->window()->globalExec();
        SecurityOrigin* origin = iter->value->window()->wrapped().document()->securityOrigin();
        result.append(std::pair<JSC::ExecState*, SecurityOrigin*>(exec, origin));
    }
}

#if ENABLE(NETSCAPE_PLUGIN_API)
NPObject* ScriptController::windowScriptNPObject()
{
    if (!m_windowScriptNPObject) {
        JSLockHolder lock(commonVM());
        if (canExecuteScripts(NotAboutToExecuteScript)) {
            // JavaScript is enabled, so there is a JavaScript window object.
            // Return an NPObject bound to the window object.
            JSDOMWindow* win = windowShell(pluginWorld())->window();
            ASSERT(win);
            Bindings::RootObject* root = bindingRootObject();
            m_windowScriptNPObject = _NPN_CreateScriptObject(0, win, root);
        } else {
            // JavaScript is not enabled, so we cannot bind the NPObject to the JavaScript window object.
            // Instead, we create an NPObject of a different class, one which is not bound to a JavaScript object.
            m_windowScriptNPObject = _NPN_CreateNoScriptObject();
        }
    }

    return m_windowScriptNPObject;
}
#endif

#if !PLATFORM(COCOA)
RefPtr<JSC::Bindings::Instance> ScriptController::createScriptInstanceForWidget(Widget* widget)
{
    if (!is<PluginViewBase>(*widget))
        return nullptr;

    return downcast<PluginViewBase>(*widget).bindingInstance();
}
#endif

JSObject* ScriptController::jsObjectForPluginElement(HTMLPlugInElement* plugin)
{
    // Can't create JSObjects when JavaScript is disabled
    if (!canExecuteScripts(NotAboutToExecuteScript))
        return 0;

    JSLockHolder lock(commonVM());

    // Create a JSObject bound to this element
    JSDOMWindow* globalObj = globalObject(pluginWorld());
    // FIXME: is normal okay? - used for NP plugins?
    JSValue jsElementValue = toJS(globalObj->globalExec(), globalObj, plugin);
    if (!jsElementValue || !jsElementValue.isObject())
        return 0;
    
    return jsElementValue.getObject();
}

#if !PLATFORM(COCOA)

void ScriptController::updatePlatformScriptObjects()
{
}

void ScriptController::disconnectPlatformScriptObjects()
{
}

#endif

void ScriptController::cleanupScriptObjectsForPlugin(void* nativeHandle)
{
    RootObjectMap::iterator it = m_rootObjects.find(nativeHandle);

    if (it == m_rootObjects.end())
        return;

    it->value->invalidate();
    m_rootObjects.remove(it);
}

void ScriptController::clearScriptObjects()
{
    JSLockHolder lock(commonVM());

    RootObjectMap::const_iterator end = m_rootObjects.end();
    for (RootObjectMap::const_iterator it = m_rootObjects.begin(); it != end; ++it)
        it->value->invalidate();

    m_rootObjects.clear();

    if (m_bindingRootObject) {
        m_bindingRootObject->invalidate();
        m_bindingRootObject = nullptr;
    }

#if ENABLE(NETSCAPE_PLUGIN_API)
    if (m_windowScriptNPObject) {
        // Call _NPN_DeallocateObject() instead of _NPN_ReleaseObject() so that we don't leak if a plugin fails to release the window
        // script object properly.
        // This shouldn't cause any problems for plugins since they should have already been stopped and destroyed at this point.
        _NPN_DeallocateObject(m_windowScriptNPObject);
        m_windowScriptNPObject = nullptr;
    }
#endif
}

JSValue ScriptController::executeScriptInWorld(DOMWrapperWorld& world, const String& script, bool forceUserGesture)
{
    UserGestureIndicator gestureIndicator(forceUserGesture ? std::optional<ProcessingUserGestureState>(ProcessingUserGesture) : std::nullopt);
    ScriptSourceCode sourceCode(script, m_frame.document()->url());

    if (!canExecuteScripts(AboutToExecuteScript) || isPaused())
        return { };

    return evaluateInWorld(sourceCode, world);
}

bool ScriptController::canExecuteScripts(ReasonForCallingCanExecuteScripts reason)
{
    if (m_frame.document() && m_frame.document()->isSandboxed(SandboxScripts)) {
        // FIXME: This message should be moved off the console once a solution to https://bugs.webkit.org/show_bug.cgi?id=103274 exists.
        if (reason == AboutToExecuteScript)
            m_frame.document()->addConsoleMessage(MessageSource::Security, MessageLevel::Error, "Blocked script execution in '" + m_frame.document()->url().stringCenterEllipsizedToLength() + "' because the document's frame is sandboxed and the 'allow-scripts' permission is not set.");
        return false;
    }

    if (!m_frame.page())
        return false;

    return m_frame.loader().client().allowScript(m_frame.settings().isScriptEnabled());
}

JSValue ScriptController::executeScript(const String& script, bool forceUserGesture, ExceptionDetails* exceptionDetails)
{
    UserGestureIndicator gestureIndicator(forceUserGesture ? std::optional<ProcessingUserGestureState>(ProcessingUserGesture) : std::nullopt);
    return executeScript(ScriptSourceCode(script, m_frame.document()->url()), exceptionDetails);
}

JSValue ScriptController::executeScript(const ScriptSourceCode& sourceCode, ExceptionDetails* exceptionDetails)
{
    if (!canExecuteScripts(AboutToExecuteScript) || isPaused())
        return { }; // FIXME: Would jsNull be better?

    // FIXME: Preventing Frame from being destroyed is essentially unnecessary.
    // https://bugs.webkit.org/show_bug.cgi?id=164763
    Ref<Frame> protector(m_frame); // Script execution can destroy the frame, and thus the ScriptController.

    return evaluate(sourceCode, exceptionDetails);
}

bool ScriptController::executeIfJavaScriptURL(const URL& url, ShouldReplaceDocumentIfJavaScriptURL shouldReplaceDocumentIfJavaScriptURL)
{
    if (!protocolIsJavaScript(url))
        return false;

    if (!m_frame.page() || !m_frame.document()->contentSecurityPolicy()->allowJavaScriptURLs(m_frame.document()->url(), eventHandlerPosition().m_line))
        return true;

    // We need to hold onto the Frame here because executing script can
    // destroy the frame.
    Ref<Frame> protector(m_frame);
    RefPtr<Document> ownerDocument(m_frame.document());

    const int javascriptSchemeLength = sizeof("javascript:") - 1;

    String decodedURL = decodeURLEscapeSequences(url.string());
    auto result = executeScript(decodedURL.substring(javascriptSchemeLength));

    // If executing script caused this frame to be removed from the page, we
    // don't want to try to replace its document!
    if (!m_frame.page())
        return true;

    String scriptResult;
    if (!result || !result.getString(windowShell(mainThreadNormalWorld())->window()->globalExec(), scriptResult))
        return true;

    // FIXME: We should always replace the document, but doing so
    //        synchronously can cause crashes:
    //        http://bugs.webkit.org/show_bug.cgi?id=16782
    if (shouldReplaceDocumentIfJavaScriptURL == ReplaceDocumentIfJavaScriptURL) {
        // We're still in a frame, so there should be a DocumentLoader.
        ASSERT(m_frame.document()->loader());
        
        // DocumentWriter::replaceDocument can cause the DocumentLoader to get deref'ed and possible destroyed,
        // so protect it with a RefPtr.
        if (RefPtr<DocumentLoader> loader = m_frame.document()->loader())
            loader->writer().replaceDocument(scriptResult, ownerDocument.get());
    }
    return true;
}

} // namespace WebCore