C++ HandleValue::isUndefined方法代码示例

/*
 * ES6 21.2.3.2.2.  Because this function only ever returns |obj| in the spec,
 * provided by the user, we omit it and just return the usual success/failure.
 */
static bool
RegExpInitialize(JSContext* cx, Handle<RegExpObject*> obj, HandleValue patternValue,
                 HandleValue flagsValue, RegExpStaticsUse staticsUse)
{
    RootedAtom pattern(cx);
    if (patternValue.isUndefined()) {
        /* Step 1. */
        pattern = cx->runtime()->emptyString;
    } else {
        /* Steps 2-3. */
        pattern = ToAtom<CanGC>(cx, patternValue);
        if (!pattern)
            return false;
    }

    /* Step 4. */
    RegExpFlag flags = RegExpFlag(0);
    if (!flagsValue.isUndefined()) {
        /* Steps 5-6. */
        RootedString flagStr(cx, ToString<CanGC>(cx, flagsValue));
        if (!flagStr)
            return false;
        /* Step 7. */
        if (!ParseRegExpFlags(cx, flagStr, &flags))
            return false;
    }

    /* Steps 9-10. */
    CompileOptions options(cx);
    frontend::TokenStream dummyTokenStream(cx, options, nullptr, 0, nullptr);
    if (!irregexp::ParsePatternSyntax(dummyTokenStream, cx->tempLifoAlloc(), pattern,
                                      flags & UnicodeFlag))
    {
        return false;
    }

    if (staticsUse == UseRegExpStatics) {
        RegExpStatics* res = cx->global()->getRegExpStatics(cx);
        if (!res)
            return false;
        flags = RegExpFlag(flags | res->getFlags());
    }

    /* Steps 11-15. */
    if (!RegExpObject::initFromAtom(cx, obj, pattern, flags))
        return false;

    /* Step 16. */
    return true;
}

bool
js::GeneratorThrowOrClose(JSContext *cx, AbstractFramePtr frame, Handle<GeneratorObject*> genObj,
                          HandleValue arg, uint32_t resumeKind)
{
    if (resumeKind == GeneratorObject::THROW) {
        cx->setPendingException(arg);
        genObj->setRunning();
    } else {
        MOZ_ASSERT(resumeKind == GeneratorObject::CLOSE);

        if (genObj->is<StarGeneratorObject>()) {
            // Store the return value in the frame's CallObject so that we can
            // return it after executing finally blocks (and potentially
            // yielding again).
            MOZ_ASSERT(arg.isObject());
            CallObject &callObj = frame.callObj();
            Shape *shape = callObj.lookup(cx, cx->names().dotGenRVal);
            callObj.setSlot(shape->slot(), arg);
        } else {
            MOZ_ASSERT(arg.isUndefined());
        }

        cx->setPendingException(MagicValue(JS_GENERATOR_CLOSING));
        genObj->setClosing();
    }
    return false;
}

bool
js::GeneratorThrowOrClose(JSContext* cx, AbstractFramePtr frame, Handle<GeneratorObject*> genObj,
                          HandleValue arg, uint32_t resumeKind)
{
    if (resumeKind == GeneratorObject::THROW) {
        cx->setPendingException(arg);
        genObj->setRunning();
    } else {
        MOZ_ASSERT(resumeKind == GeneratorObject::CLOSE);

        if (genObj->is<StarGeneratorObject>()) {
            MOZ_ASSERT(arg.isObject());
            frame.setReturnValue(arg);
        } else {
            MOZ_ASSERT(arg.isUndefined());
        }

        cx->setPendingException(MagicValue(JS_GENERATOR_CLOSING));
        genObj->setClosing();
    }
    return false;
}

bool
js::DirectEvalStringFromIon(JSContext *cx,
                            HandleObject scopeobj, HandleScript callerScript,
                            HandleValue thisValue, HandleString str,
                            jsbytecode *pc, MutableHandleValue vp)
{
    AssertInnerizedScopeChain(cx, *scopeobj);

    Rooted<GlobalObject*> scopeObjGlobal(cx, &scopeobj->global());
    if (!GlobalObject::isRuntimeCodeGenEnabled(cx, scopeObjGlobal)) {
        JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr, JSMSG_CSP_BLOCKED_EVAL);
        return false;
    }

    // ES5 15.1.2.1 steps 2-8.

    unsigned staticLevel = callerScript->staticLevel() + 1;

    Rooted<JSFlatString*> flatStr(cx, str->ensureFlat(cx));
    if (!flatStr)
        return false;

    EvalJSONResult ejr = TryEvalJSON(cx, callerScript, flatStr, vp);
    if (ejr != EvalJSON_NotJSON)
        return ejr == EvalJSON_Success;

    EvalScriptGuard esg(cx);

    esg.lookupInEvalCache(flatStr, callerScript, pc);

    if (!esg.foundScript()) {
        RootedScript maybeScript(cx);
        const char *filename;
        unsigned lineno;
        JSPrincipals *originPrincipals;
        uint32_t pcOffset;
        DescribeScriptedCallerForCompilation(cx, &maybeScript, &filename, &lineno, &pcOffset,
                                              &originPrincipals, CALLED_FROM_JSOP_EVAL);

        const char *introducerFilename = filename;
        if (maybeScript && maybeScript->scriptSource()->introducerFilename())
            introducerFilename = maybeScript->scriptSource()->introducerFilename();

        CompileOptions options(cx);
        options.setFileAndLine(filename, 1)
               .setCompileAndGo(true)
               .setForEval(true)
               .setNoScriptRval(false)
               .setOriginPrincipals(originPrincipals)
               .setIntroductionInfo(introducerFilename, "eval", lineno, maybeScript, pcOffset);

        AutoStableStringChars flatChars(cx);
        if (!flatChars.initTwoByte(cx, flatStr))
            return false;

        const char16_t *chars = flatChars.twoByteRange().start().get();
        SourceBufferHolder::Ownership ownership = flatChars.maybeGiveOwnershipToCaller()
                                                  ? SourceBufferHolder::GiveOwnership
                                                  : SourceBufferHolder::NoOwnership;
        SourceBufferHolder srcBuf(chars, flatStr->length(), ownership);
        JSScript *compiled = frontend::CompileScript(cx, &cx->tempLifoAlloc(),
                                                     scopeobj, callerScript, options,
                                                     srcBuf, flatStr, staticLevel);
        if (!compiled)
            return false;

        esg.setNewScript(compiled);
    }

    // Primitive 'this' values should have been filtered out by Ion. If boxed,
    // the calling frame cannot be updated to store the new object.
    JS_ASSERT(thisValue.isObject() || thisValue.isUndefined() || thisValue.isNull());

    return ExecuteKernel(cx, esg.script(), *scopeobj, thisValue, ExecuteType(DIRECT_EVAL),
                         NullFramePtr() /* evalInFrame */, vp.address());
}

bool
js::DirectEvalFromIon(JSContext *cx,
                      HandleObject scopeobj, HandleScript callerScript,
                      HandleValue thisValue, HandleString str,
                      MutableHandleValue vp)
{
    AssertInnerizedScopeChain(cx, *scopeobj);

    Rooted<GlobalObject*> scopeObjGlobal(cx, &scopeobj->global());
    if (!GlobalObject::isRuntimeCodeGenEnabled(cx, scopeObjGlobal)) {
        JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL, JSMSG_CSP_BLOCKED_EVAL);
        return false;
    }

    // ES5 15.1.2.1 steps 2-8.

    unsigned staticLevel = callerScript->staticLevel + 1;

    Rooted<JSStableString*> stableStr(cx, str->ensureStable(cx));
    if (!stableStr)
        return false;

    StableCharPtr chars = stableStr->chars();
    size_t length = stableStr->length();

    EvalJSONResult ejr = TryEvalJSON(cx, callerScript, chars, length, vp);
    if (ejr != EvalJSON_NotJSON)
        return ejr == EvalJSON_Success;

    EvalScriptGuard esg(cx);

    // Ion will not perform cross compartment direct eval calls.
    JSPrincipals *principals = cx->compartment->principals;

    esg.lookupInEvalCache(stableStr, callerScript->function(), staticLevel);

    if (!esg.foundScript()) {
        unsigned lineno;
        const char *filename;
        JSPrincipals *originPrincipals;
        CurrentScriptFileLineOrigin(cx, &filename, &lineno, &originPrincipals,
                                    CALLED_FROM_JSOP_EVAL);

        CompileOptions options(cx);
        options.setFileAndLine(filename, lineno)
               .setCompileAndGo(true)
               .setNoScriptRval(false)
               .setPrincipals(principals)
               .setOriginPrincipals(originPrincipals);
        UnrootedScript compiled = frontend::CompileScript(cx, scopeobj, callerScript, options,
                                                          chars.get(), length, stableStr, staticLevel);
        if (!compiled)
            return false;

        esg.setNewScript(compiled);
    }

    // Primitive 'this' values should have been filtered out by Ion. If boxed,
    // the calling frame cannot be updated to store the new object.
    JS_ASSERT(thisValue.isObject() || thisValue.isUndefined() || thisValue.isNull());

    return ExecuteKernel(cx, esg.script(), *scopeobj, thisValue, ExecuteType(DIRECT_EVAL),
                         NullFramePtr() /* evalInFrame */, vp.address());
}

bool
js::DirectEvalStringFromIon(JSContext* cx,
                            HandleObject scopeobj, HandleScript callerScript,
                            HandleValue thisValue, HandleValue newTargetValue,
                            HandleString str, jsbytecode* pc, MutableHandleValue vp)
{
    AssertInnerizedScopeChain(cx, *scopeobj);

    Rooted<GlobalObject*> scopeObjGlobal(cx, &scopeobj->global());
    if (!GlobalObject::isRuntimeCodeGenEnabled(cx, scopeObjGlobal)) {
        JS_ReportErrorNumber(cx, GetErrorMessage, nullptr, JSMSG_CSP_BLOCKED_EVAL);
        return false;
    }

    // ES5 15.1.2.1 steps 2-8.

    unsigned staticLevel = callerScript->staticLevel() + 1;

    RootedLinearString linearStr(cx, str->ensureLinear(cx));
    if (!linearStr)
        return false;

    EvalJSONResult ejr = TryEvalJSON(cx, linearStr, vp);
    if (ejr != EvalJSON_NotJSON)
        return ejr == EvalJSON_Success;

    EvalScriptGuard esg(cx);

    esg.lookupInEvalCache(linearStr, callerScript, pc);

    if (!esg.foundScript()) {
        RootedScript maybeScript(cx);
        const char* filename;
        unsigned lineno;
        bool mutedErrors;
        uint32_t pcOffset;
        DescribeScriptedCallerForCompilation(cx, &maybeScript, &filename, &lineno, &pcOffset,
                                             &mutedErrors, CALLED_FROM_JSOP_EVAL);

        const char* introducerFilename = filename;
        if (maybeScript && maybeScript->scriptSource()->introducerFilename())
            introducerFilename = maybeScript->scriptSource()->introducerFilename();

        RootedObject enclosing(cx, callerScript->innermostStaticScope(pc));
        Rooted<StaticEvalObject*> staticScope(cx, StaticEvalObject::create(cx, enclosing));
        if (!staticScope)
            return false;

        CompileOptions options(cx);
        options.setFileAndLine(filename, 1)
               .setIsRunOnce(true)
               .setForEval(true)
               .setNoScriptRval(false)
               .setMutedErrors(mutedErrors)
               .setIntroductionInfo(introducerFilename, "eval", lineno, maybeScript, pcOffset)
               .maybeMakeStrictMode(IsStrictEvalPC(pc));

        AutoStableStringChars linearChars(cx);
        if (!linearChars.initTwoByte(cx, linearStr))
            return false;

        const char16_t* chars = linearChars.twoByteRange().start().get();
        SourceBufferHolder::Ownership ownership = linearChars.maybeGiveOwnershipToCaller()
                                                  ? SourceBufferHolder::GiveOwnership
                                                  : SourceBufferHolder::NoOwnership;
        SourceBufferHolder srcBuf(chars, linearStr->length(), ownership);
        JSScript* compiled = frontend::CompileScript(cx, &cx->tempLifoAlloc(),
                                                     scopeobj, staticScope, callerScript,
                                                     options, srcBuf, linearStr, staticLevel);
        if (!compiled)
            return false;

        if (compiled->strict())
            staticScope->setStrict();

        esg.setNewScript(compiled);
    }

    // Primitive 'this' values should have been filtered out by Ion. If boxed,
    // the calling frame cannot be updated to store the new object.
    MOZ_ASSERT(thisValue.isObject() || thisValue.isUndefined() || thisValue.isNull());

    // When eval'ing strict code in a non-strict context, compute the 'this'
    // value to use from what the caller passed in. This isn't necessary if
    // the callee is not strict, as it will compute the non-strict 'this'
    // value as necessary while it executes.
    RootedValue nthisValue(cx, thisValue);
    if (!callerScript->strict() && esg.script()->strict() && !thisValue.isObject()) {
        JSObject* obj = BoxNonStrictThis(cx, thisValue);
        if (!obj)
            return false;
        nthisValue = ObjectValue(*obj);
    }

    return ExecuteKernel(cx, esg.script(), *scopeobj, nthisValue, newTargetValue,
                         ExecuteType(DIRECT_EVAL), NullFramePtr() /* evalInFrame */, vp.address());
}

/*
 * Experimental implementation of ArrayBuffer.transfer:
 *   https://gist.github.com/andhow/95fb9e49996615764eff
 * which is currently in the early stages of proposal for ES7.
 */
bool
ArrayBufferObject::fun_transfer(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    HandleValue oldBufferArg = args.get(0);
    HandleValue newByteLengthArg = args.get(1);

    if (!oldBufferArg.isObject()) {
        JS_ReportErrorNumber(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_BAD_ARGS);
        return false;
    }

    RootedObject oldBufferObj(cx, &oldBufferArg.toObject());
    ESClassValue cls;
    if (!GetBuiltinClass(cx, oldBufferObj, &cls))
        return false;
    if (cls != ESClass_ArrayBuffer) {
        JS_ReportErrorNumber(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_BAD_ARGS);
        return false;
    }

    // Beware: oldBuffer can point across compartment boundaries. ArrayBuffer
    // contents are not compartment-specific so this is safe.
    Rooted<ArrayBufferObject*> oldBuffer(cx);
    if (oldBufferObj->is<ArrayBufferObject>()) {
        oldBuffer = &oldBufferObj->as<ArrayBufferObject>();
    } else {
        JSObject* unwrapped = CheckedUnwrap(oldBufferObj);
        if (!unwrapped || !unwrapped->is<ArrayBufferObject>()) {
            JS_ReportErrorNumber(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_BAD_ARGS);
            return false;
        }
        oldBuffer = &unwrapped->as<ArrayBufferObject>();
    }

    size_t oldByteLength = oldBuffer->byteLength();
    size_t newByteLength;
    if (newByteLengthArg.isUndefined()) {
        newByteLength = oldByteLength;
    } else {
        int32_t i32;
        if (!ToInt32(cx, newByteLengthArg, &i32))
            return false;
        if (i32 < 0) {
            JS_ReportErrorNumber(cx, GetErrorMessage, nullptr, JSMSG_BAD_ARRAY_LENGTH);
            return false;
        }
        newByteLength = size_t(i32);
    }

    if (oldBuffer->isNeutered()) {
        JS_ReportErrorNumber(cx, GetErrorMessage, nullptr, JSMSG_TYPED_ARRAY_DETACHED);
        return false;
    }

    UniquePtr<uint8_t, JS::FreePolicy> newData;
    if (!newByteLength) {
        if (!ArrayBufferObject::neuter(cx, oldBuffer, oldBuffer->contents()))
            return false;
    } else {
# if defined(ASMJS_MAY_USE_SIGNAL_HANDLERS_FOR_OOB)
        // With a 4gb mapped asm.js buffer, we can simply enable/disable access
        // to the delta as long as the requested length is page-sized.
        if (oldBuffer->isAsmJSMapped() && (newByteLength % AsmJSPageSize) == 0)
            return TransferAsmJSMappedBuffer(cx, args, oldBuffer, newByteLength);
# endif

        // Since we try to realloc below, only allow stealing malloc'd buffers.
        // If !hasMallocedContents, stealContents will malloc a copy which we
        // can then realloc.
        bool steal = oldBuffer->hasMallocedContents();
        auto stolenContents = ArrayBufferObject::stealContents(cx, oldBuffer, steal);
        if (!stolenContents)
            return false;

        UniquePtr<uint8_t, JS::FreePolicy> oldData(stolenContents.data());
        if (newByteLength > oldByteLength) {
            // In theory, realloc+memset(0) can be optimized to avoid touching
            // any pages (by using OS page mapping tricks). However, in
            // practice, we don't seem to get this optimization in Firefox with
            // jemalloc so calloc+memcpy are faster.
            newData.reset(cx->runtime()->pod_callocCanGC<uint8_t>(newByteLength));
            if (newData) {
                memcpy(newData.get(), oldData.get(), oldByteLength);
            } else {
                // Try malloc before giving up since it might be able to succed
                // by resizing oldData in-place.
                newData.reset(cx->pod_realloc(oldData.get(), oldByteLength, newByteLength));
                if (!newData)
                    return false;
                oldData.release();
                memset(newData.get() + oldByteLength, 0, newByteLength - oldByteLength);
            }
        } else if (newByteLength < oldByteLength) {
            newData.reset(cx->pod_realloc(oldData.get(), oldByteLength, newByteLength));
//.........这里部分代码省略.........

bool
ExportFunction(JSContext *cx, HandleValue vfunction, HandleValue vscope, HandleValue voptions,
               MutableHandleValue rval)
{
    bool hasOptions = !voptions.isUndefined();
    if (!vscope.isObject() || !vfunction.isObject() || (hasOptions && !voptions.isObject())) {
        JS_ReportError(cx, "Invalid argument");
        return false;
    }

    RootedObject funObj(cx, &vfunction.toObject());
    RootedObject targetScope(cx, &vscope.toObject());
    ExportFunctionOptions options(cx, hasOptions ? &voptions.toObject() : nullptr);
    if (hasOptions && !options.Parse())
        return false;

    // We can only export functions to scopes those are transparent for us,
    // so if there is a security wrapper around targetScope we must throw.
    targetScope = CheckedUnwrap(targetScope);
    if (!targetScope) {
        JS_ReportError(cx, "Permission denied to export function into scope");
        return false;
    }

    if (js::IsScriptedProxy(targetScope)) {
        JS_ReportError(cx, "Defining property on proxy object is not allowed");
        return false;
    }

    {
        // We need to operate in the target scope from here on, let's enter
        // its compartment.
        JSAutoCompartment ac(cx, targetScope);

        // Unwrapping to see if we have a callable.
        funObj = UncheckedUnwrap(funObj);
        if (!JS_ObjectIsCallable(cx, funObj)) {
            JS_ReportError(cx, "First argument must be a function");
            return false;
        }

        RootedId id(cx, options.defineAs);
        if (JSID_IS_VOID(id)) {
            // If there wasn't any function name specified,
            // copy the name from the function being imported.
            JSFunction *fun = JS_GetObjectFunction(funObj);
            RootedString funName(cx, JS_GetFunctionId(fun));
            if (!funName)
                funName = JS_InternString(cx, "");

            if (!JS_StringToId(cx, funName, &id))
                return false;
        }
        MOZ_ASSERT(JSID_IS_STRING(id));

        // The function forwarder will live in the target compartment. Since
        // this function will be referenced from its private slot, to avoid a
        // GC hazard, we must wrap it to the same compartment.
        if (!JS_WrapObject(cx, &funObj))
            return false;

        // And now, let's create the forwarder function in the target compartment
        // for the function the be exported.
        FunctionForwarderOptions forwarderOptions(cx);
        forwarderOptions.allowCallbacks = options.allowCallbacks;
        if (!NewFunctionForwarder(cx, id, funObj, forwarderOptions, rval)) {
            JS_ReportError(cx, "Exporting function failed");
            return false;
        }

        // We have the forwarder function in the target compartment. If
        // defineAs was set, we also need to define it as a property on
        // the target.
        if (!JSID_IS_VOID(options.defineAs)) {
            if (!JS_DefinePropertyById(cx, targetScope, id, rval, JSPROP_ENUMERATE,
                                       JS_PropertyStub, JS_StrictPropertyStub)) {
                return false;
            }
        }
    }

    // Finally we have to re-wrap the exported function back to the caller compartment.
    if (!JS_WrapValue(cx, rval))
        return false;

    return true;
}

bool
js::DirectEvalStringFromIon(JSContext *cx,
                            HandleObject scopeobj, HandleScript callerScript,
                            HandleValue thisValue, HandleString str,
                            jsbytecode *pc, MutableHandleValue vp)
{
    AssertInnerizedScopeChain(cx, *scopeobj);

    Rooted<GlobalObject*> scopeObjGlobal(cx, &scopeobj->global());
    if (!GlobalObject::isRuntimeCodeGenEnabled(cx, scopeObjGlobal)) {
        JS_ReportErrorNumber(cx, js_GetErrorMessage, nullptr, JSMSG_CSP_BLOCKED_EVAL);
        return false;
    }

    // ES5 15.1.2.1 steps 2-8.

    unsigned staticLevel = callerScript->staticLevel() + 1;

    Rooted<JSFlatString*> flatStr(cx, str->ensureFlat(cx));
    if (!flatStr)
        return false;

    size_t length = flatStr->length();
    ConstTwoByteChars chars(flatStr->chars(), length);

    EvalJSONResult ejr = TryEvalJSON(cx, callerScript, chars, length, vp);
    if (ejr != EvalJSON_NotJSON)
        return ejr == EvalJSON_Success;

    EvalScriptGuard esg(cx);

    // Ion will not perform cross compartment direct eval calls.
    JSPrincipals *principals = cx->compartment()->principals;

    esg.lookupInEvalCache(flatStr, callerScript, pc);

    if (!esg.foundScript()) {
        JSScript *script;
        const char *filename;
        unsigned lineno;
        JSPrincipals *originPrincipals;
        uint32_t pcOffset;
        CurrentScriptFileLineOrigin(cx, &script, &filename, &lineno, &pcOffset,
                                    &originPrincipals, CALLED_FROM_JSOP_EVAL);

        const char *introducerFilename = filename;
        if (script && script->scriptSource()->introducerFilename())
            introducerFilename = script->scriptSource()->introducerFilename();

        CompileOptions options(cx);
        options.setFileAndLine(filename, 1)
               .setCompileAndGo(true)
               .setForEval(true)
               .setNoScriptRval(false)
               .setPrincipals(principals)
               .setOriginPrincipals(originPrincipals)
               .setIntroductionInfo(introducerFilename, "eval", lineno, script, pcOffset);
        JSScript *compiled = frontend::CompileScript(cx, &cx->tempLifoAlloc(),
                                                     scopeobj, callerScript, options,
                                                     chars.get(), length, flatStr, staticLevel);
        if (!compiled)
            return false;

        MarkFunctionsWithinEvalScript(compiled);

        esg.setNewScript(compiled);
    }

    // Primitive 'this' values should have been filtered out by Ion. If boxed,
    // the calling frame cannot be updated to store the new object.
    JS_ASSERT(thisValue.isObject() || thisValue.isUndefined() || thisValue.isNull());

    return ExecuteKernel(cx, esg.script(), *scopeobj, thisValue, ExecuteType(DIRECT_EVAL),
                         NullFramePtr() /* evalInFrame */, vp.address());
}