C++ HandleValue类代码示例

static bool
IsVectorObject(HandleValue v)
{
    if (!v.isObject())
        return false;

    JSObject &obj = v.toObject();
    if (!obj.is<TypedObject>())
        return false;

    TypeDescr &typeRepr = obj.as<TypedObject>().typeDescr();
    if (typeRepr.kind() != TypeDescr::X4)
        return false;

    return typeRepr.as<X4TypeDescr>().type() == V::type;
}

bool
JS::detail::CallMethodIfWrapped(JSContext* cx, IsAcceptableThis test, NativeImpl impl,
                                const CallArgs& args)
{
    HandleValue thisv = args.thisv();
    MOZ_ASSERT(!test(thisv));

    if (thisv.isObject()) {
        JSObject& thisObj = args.thisv().toObject();
        if (thisObj.is<ProxyObject>())
            return Proxy::nativeCall(cx, test, impl, args);
    }

    ReportIncompatible(cx, args);
    return false;
}

static Elem
TypedObjectMemory(HandleValue v)
{
    TypedObject &obj = v.toObject().as<TypedObject>();
    MOZ_ASSERT(!obj.owner().isNeutered());
    return reinterpret_cast<Elem>(obj.typedMem());
}

static bool
CheckVectorObject(HandleValue v, X4TypeDescr::Type expectedType)
{
    if (!v.isObject())
        return false;

    JSObject &obj = v.toObject();
    if (!obj.is<TypedObject>())
        return false;

    TypeDescr &typeRepr = obj.as<TypedObject>().typeDescr();
    if (typeRepr.kind() != type::X4)
        return false;

    return typeRepr.as<X4TypeDescr>().type() == expectedType;
}

/*
 * 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))
        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;
}

NS_IMETHODIMP
nsJSIID::HasInstance(nsIXPConnectWrappedNative* wrapper,
                     JSContext* cx, JSObject * /* unused */,
                     HandleValue val, bool* bp, bool* _retval)
{
    *bp = false;

    if (val.isPrimitive())
        return NS_OK;

    // we have a JSObject
    RootedObject obj(cx, &val.toObject());

    const nsIID* iid;
    mInfo->GetIIDShared(&iid);
    return xpc::HasInstance(cx, obj, iid, bp);
}

MOZ_ALWAYS_INLINE bool
bool_toSource_impl(JSContext *cx, CallArgs args)
{
    HandleValue thisv = args.thisv();
    JS_ASSERT(IsBoolean(thisv));

    bool b = thisv.isBoolean() ? thisv.toBoolean() : thisv.toObject().as<BooleanObject>().unbox();

    StringBuffer sb(cx);
    if (!sb.append("(new Boolean(") || !BooleanToStringBuffer(b, sb) || !sb.append("))"))
        return false;

    JSString *str = sb.finishString();
    if (!str)
        return false;
    args.rval().setString(str);
    return true;
}

bool
AccessCheck::checkPassToPrivilegedCode(JSContext* cx, HandleObject wrapper, HandleValue v)
{
    // Primitives are fine.
    if (!v.isObject())
        return true;
    RootedObject obj(cx, &v.toObject());

    // Non-wrappers are fine.
    if (!js::IsWrapper(obj))
        return true;

    // CPOWs use COWs (in the unprivileged junk scope) for all child->parent
    // references. Without this test, the child process wouldn't be able to
    // pass any objects at all to CPOWs.
    if (mozilla::jsipc::IsWrappedCPOW(obj) &&
        js::GetObjectCompartment(wrapper) == js::GetObjectCompartment(xpc::UnprivilegedJunkScope()) &&
        XRE_IsParentProcess())
    {
        return true;
    }

    // COWs are fine to pass to chrome if and only if they have __exposedProps__,
    // since presumably content should never have a reason to pass an opaque
    // object back to chrome.
    if (AccessCheck::isChrome(js::UncheckedUnwrap(wrapper)) && WrapperFactory::IsCOW(obj)) {
        RootedObject target(cx, js::UncheckedUnwrap(obj));
        JSAutoCompartment ac(cx, target);
        RootedId id(cx, GetRTIdByIndex(cx, XPCJSRuntime::IDX_EXPOSEDPROPS));
        bool found = false;
        if (!JS_HasPropertyById(cx, target, id, &found))
            return false;
        if (found)
            return true;
    }

    // Same-origin wrappers are fine.
    if (AccessCheck::wrapperSubsumes(obj))
        return true;

    // Badness.
    JS_ReportError(cx, "Permission denied to pass object to privileged code");
    return false;
}

static bool
ProtoGetterImpl(JSContext *cx, CallArgs args)
{
    JS_ASSERT(TestProtoGetterThis(args.thisv()));

    HandleValue thisv = args.thisv();
    if (thisv.isPrimitive() && !BoxNonStrictThis(cx, args))
        return false;

    unsigned dummy;
    RootedObject obj(cx, &args.thisv().toObject());
    RootedId nid(cx, NameToId(cx->names().proto));
    RootedValue v(cx);
    if (!CheckAccess(cx, obj, nid, JSACC_PROTO, &v, &dummy))
        return false;

    args.rval().set(v);
    return true;
}

static bool
ProtoGetter(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);
    HandleValue thisv = args.thisv();
    if (thisv.isNullOrUndefined()) {
        ReportIncompatible(cx, args);
        return false;
    }
    if (thisv.isPrimitive() && !BoxNonStrictThis(cx, args))
        return false;

    RootedObject obj(cx, &args.thisv().toObject());
    RootedObject proto(cx);
    if (!GetPrototype(cx, obj, &proto))
        return false;
    args.rval().setObjectOrNull(proto);
    return true;
}

bool
CreateObjectIn(JSContext *cx, HandleValue vobj, CreateObjectInOptions &options,
               MutableHandleValue rval)
{
    if (!vobj.isObject()) {
        JS_ReportError(cx, "Expected an object as the target scope");
        return false;
    }

    RootedObject scope(cx, js::CheckedUnwrap(&vobj.toObject()));
    if (!scope) {
        JS_ReportError(cx, "Permission denied to create object in the target scope");
        return false;
    }

    bool define = !JSID_IS_VOID(options.defineAs);

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

    RootedObject obj(cx);
    {
        JSAutoCompartment ac(cx, scope);
        obj = JS_NewObject(cx, nullptr, JS::NullPtr(), scope);
        if (!obj)
            return false;

        if (define) {
            if (!JS_DefinePropertyById(cx, scope, options.defineAs, obj, JSPROP_ENUMERATE,
                                       JS_PropertyStub, JS_StrictPropertyStub))
                return false;
        }
    }

    rval.setObject(*obj);
    if (!WrapperFactory::WaiveXrayAndWrap(cx, rval))
        return false;

    return true;
}

bool
WrapperOwner::DOMQI(JSContext* cx, JS::HandleObject proxy, JS::CallArgs& args)
{
    // Someone's calling us, handle nsISupports specially to avoid unnecessary
    // CPOW traffic.
    HandleValue id = args[0];
    if (id.isObject()) {
        RootedObject idobj(cx, &id.toObject());
        nsCOMPtr<nsIJSID> jsid;

        nsresult rv = UnwrapArg<nsIJSID>(cx, idobj, getter_AddRefs(jsid));
        if (NS_SUCCEEDED(rv)) {
            MOZ_ASSERT(jsid, "bad wrapJS");
            const nsID* idptr = jsid->GetID();
            if (idptr->Equals(NS_GET_IID(nsISupports))) {
                args.rval().set(args.thisv());
                return true;
            }

            // Webidl-implemented DOM objects never have nsIClassInfo.
            if (idptr->Equals(NS_GET_IID(nsIClassInfo)))
                return Throw(cx, NS_ERROR_NO_INTERFACE);
        }
    }

    // It wasn't nsISupports, call into the other process to do the QI for us
    // (since we don't know what other interfaces our object supports). Note
    // that we have to use JS_GetPropertyDescriptor here to avoid infinite
    // recursion back into CPOWDOMQI via WrapperOwner::get().
    // We could stash the actual QI function on our own function object to avoid
    // if we're called multiple times, but since we're transient, there's no
    // point right now.
    JS::Rooted<PropertyDescriptor> propDesc(cx);
    if (!JS_GetPropertyDescriptor(cx, proxy, "QueryInterface", &propDesc))
        return false;

    if (!propDesc.value().isObject()) {
        MOZ_ASSERT_UNREACHABLE("We didn't get QueryInterface off a node");
        return Throw(cx, NS_ERROR_UNEXPECTED);
    }
    return JS_CallFunctionValue(cx, proxy, propDesc.value(), args, args.rval());
}

static bool
ProtoSetter(JSContext* cx, unsigned argc, Value* vp)
{
    CallArgs args = CallArgsFromVp(argc, vp);

    // Do this here, rather than after the this-check so even likely-buggy
    // use of the __proto__ setter on unacceptable values, where no subsequent
    // use occurs on an acceptable value, will trigger a warning.
    RootedObject callee(cx, &args.callee());
    if (!GlobalObject::warnOnceAboutPrototypeMutation(cx, callee))
       return false;

    HandleValue thisv = args.thisv();
    if (thisv.isNullOrUndefined()) {
        ReportIncompatible(cx, args);
        return false;
    }
    if (thisv.isPrimitive()) {
        // Mutating a boxed primitive's [[Prototype]] has no side effects.
        args.rval().setUndefined();
        return true;
    }

    if (!cx->runningWithTrustedPrincipals())
        ++sSetProtoCalled;

    Rooted<JSObject*> obj(cx, &args.thisv().toObject());

    /* Do nothing if __proto__ isn't being set to an object or null. */
    if (args.length() == 0 || !args[0].isObjectOrNull()) {
        args.rval().setUndefined();
        return true;
    }

    Rooted<JSObject*> newProto(cx, args[0].toObjectOrNull());
    if (!SetPrototype(cx, obj, newProto))
        return false;

    args.rval().setUndefined();
    return true;
}

bool
js::ToSimdConstant(JSContext* cx, HandleValue v, jit::SimdConstant* out)
{
    typedef typename V::Elem Elem;
    Rooted<TypeDescr*> typeDescr(cx, &V::GetTypeDescr(*cx->global()));
    if (!IsVectorObject<V>(v))
        return ErrorWrongTypeArg(cx, 1, typeDescr);

    Elem* mem = reinterpret_cast<Elem*>(v.toObject().as<TypedObject>().typedMem());
    *out = jit::SimdConstant::CreateX4(mem);
    return true;
}

static bool
GetDataProperty(JSContext *cx, HandleValue objVal, HandlePropertyName field, MutableHandleValue v)
{
    if (!objVal.isObject())
        return LinkFail(cx, "accessing property of non-object");

    Rooted<JSPropertyDescriptor> desc(cx);
    RootedObject obj(cx, &objVal.toObject());
    RootedId id(cx, NameToId(field));
    if (!JS_GetPropertyDescriptorById(cx, obj, id, 0, &desc))
        return false;

    if (!desc.object())
        return LinkFail(cx, "property not present on object");

    if (desc.hasGetterOrSetterObject())
        return LinkFail(cx, "property is not a data property");

    v.set(desc.value());
    return true;
}