#include "config.h"

#import "JavaScriptCore.h"

#if JSC_OBJC_API_ENABLED

#import "APICast.h"

#import "APIUtils.h"

#import "JSAPIWrapperObject.h"

#import "JSCInlines.h"

#import "JSCallbackObject.h"

#import "JSContextInternal.h"

#import "JSWrapperMap.h"

#import "ObjCCallbackFunction.h"

#import "ObjcRuntimeExtras.h"

#import "ObjectConstructor.h"

#import "WeakGCMap.h"

#import "WeakGCMapInlines.h"

#import <wtf/Vector.h>

#import <wtf/spi/darwin/dyldSPI.h>

#include <mach-o/dyld.h>

#if PLATFORM(APPLETV)

#else

static constexpr int32_t firstJavaScriptCoreVersionWithInitConstructorSupport = 0x21A0400; // 538.4.0

#if PLATFORM(IOS_FAMILY)

static constexpr uint32_t firstSDKVersionWithInitConstructorSupport = DYLD_IOS_VERSION_10_0;

#elif PLATFORM(MAC)

static constexpr uint32_t firstSDKVersionWithInitConstructorSupport = 0xA0A00; // OSX 10.10.0

#endif

#endif

@class JSObjCClassInfo;

@interface JSWrapperMap ()

- (JSObjCClassInfo*)classInfoForClass:(Class)cls;

static constexpr unsigned InitialBufferSize { 256 };

static NSString *selectorToPropertyName(const char* start)

{

// Use 'index' to check for colons, if there are none, this is easy!

const char* firstColon = strchr(start, ':');

if (!firstColon)

return [NSString stringWithUTF8String:start];

// 'header' is the length of string up to the first colon.

size_t header = firstColon - start;

// The new string needs to be long enough to hold 'header', plus the remainder of the string, excluding

// at least one ':', but including a '\0'. (This is conservative if there are more than one ':').

Vector<char, InitialBufferSize> buffer(header + strlen(firstColon + 1) + 1);

// Copy 'header' characters, set output to point to the end of this & input to point past the first ':'.

memcpy(buffer.data(), start, header);

char* output = buffer.data() + header;

const char* input = start + header + 1;

// On entry to the loop, we have already skipped over a ':' from the input.

while (true) {

char c;

// Skip over any additional ':'s. We'll leave c holding the next character after the

// last ':', and input pointing past c.

while ((c = *(input++)) == ':');

// Copy the character, converting to upper case if necessary.

// If the character we copy is '\0', then we're done!

if (!(*(output++) = toASCIIUpper(c)))

goto done;

// Loop over characters other than ':'.

while ((c = *(input++)) != ':') {

// Copy the character.

// If the character we copy is '\0', then we're done!

if (!(*(output++) = c))

goto done;

}

// If we get here, we've consumed a ':' - wash, rinse, repeat.

}

done:

return [NSString stringWithUTF8String:buffer.data()];

}

static bool constructorHasInstance(JSContextRef ctx, JSObjectRef constructorRef, JSValueRef possibleInstance, JSValueRef*)

{

JSC::JSGlobalObject* globalObject = toJS(ctx);

JSC::VM& vm = globalObject->vm();

JSC::JSLockHolder locker(vm);

JSC::JSObject* constructor = toJS(constructorRef);

JSC::JSValue instance = toJS(globalObject, possibleInstance);

return JSC::JSObject::defaultHasInstance(globalObject, instance, constructor->get(globalObject, vm.propertyNames->prototype));

}

static JSC::JSObject* makeWrapper(JSContextRef ctx, JSClassRef jsClass, id wrappedObject)

{

JSC::JSGlobalObject* globalObject = toJS(ctx);

JSC::VM& vm = globalObject->vm();

JSC::JSLockHolder locker(vm);

ASSERT(jsClass);

JSC::JSCallbackObject<JSC::JSAPIWrapperObject>* object = JSC::JSCallbackObject<JSC::JSAPIWrapperObject>::create(globalObject, globalObject->objcWrapperObjectStructure(), jsClass, 0);

object->setWrappedObject((__bridge void*)wrappedObject);

if (JSC::JSObject* prototype = jsClass->prototype(globalObject))

object->setPrototypeDirect(vm, prototype);

return object;

}

static JSC::JSObject *objectWithCustomBrand(JSContext *context, NSString *brand, Class cls = 0)

{

JSClassDefinition definition;

definition = kJSClassDefinitionEmpty;

definition.className = [brand UTF8String];

JSClassRef classRef = JSClassCreate(&definition);

JSC::JSObject* result = makeWrapper([context JSGlobalContextRef], classRef, cls);

JSClassRelease(classRef);

return result;

}

static JSC::JSObject *constructorWithCustomBrand(JSContext *context, NSString *brand, Class cls)

{

JSClassDefinition definition;

definition = kJSClassDefinitionEmpty;

definition.className = [brand UTF8String];

definition.hasInstance = constructorHasInstance;

JSClassRef classRef = JSClassCreate(&definition);

JSC::JSObject* result = makeWrapper([context JSGlobalContextRef], classRef, cls);

JSClassRelease(classRef);

return result;

}

static NSMutableDictionary *createRenameMap(Protocol *protocol, BOOL isInstanceMethod)

{

NSMutableDictionary *renameMap = [[NSMutableDictionary alloc] init];

forEachMethodInProtocol(protocol, NO, isInstanceMethod, ^(SEL sel, const char*){

NSString *rename = @(sel_getName(sel));

NSRange range = [rename rangeOfString:@"__JS_EXPORT_AS__"];

if (range.location == NSNotFound)

return;

NSString *selector = [rename substringToIndex:range.location];

NSUInteger begin = range.location + range.length;

NSUInteger length = [rename length] - begin - 1;

NSString *name = [rename substringWithRange:(NSRange){ begin, length }];

renameMap[selector] = name;

});

return renameMap;

}

inline void putNonEnumerable(JSContext *context, JSValue *base, NSString *propertyName, JSValue *value)

{

if (![base isObject])

return;

JSC::JSGlobalObject* globalObject = toJS([context JSGlobalContextRef]);

JSC::VM& vm = globalObject->vm();

JSC::JSLockHolder locker(vm);

auto scope = DECLARE_CATCH_SCOPE(vm);

JSC::JSObject* baseObject = JSC::asObject(toJS(globalObject, [base JSValueRef]));

auto name = OpaqueJSString::tryCreate(propertyName);

if (!name)

return;

JSC::PropertyDescriptor descriptor;

descriptor.setValue(toJS(globalObject, [value JSValueRef]));

descriptor.setEnumerable(false);

descriptor.setConfigurable(true);

descriptor.setWritable(true);

bool shouldThrow = false;

baseObject->methodTable(vm)->defineOwnProperty(baseObject, globalObject, name->identifier(&vm), descriptor, shouldThrow);

JSValueRef exception = 0;

if (handleExceptionIfNeeded(scope, [context JSGlobalContextRef], &exception) == ExceptionStatus::DidThrow)

[context valueFromNotifyException:exception];

}

static bool isInitFamilyMethod(NSString *name)

{

NSUInteger i = 0;

// Skip over initial underscores.

for (; i < [name length]; ++i) {

if ([name characterAtIndex:i] != '_')

break;

}

// Match 'init'.

NSUInteger initIndex = 0;

NSString* init = @"init";

for (; i < [name length] && initIndex < [init length]; ++i, ++initIndex) {

if ([name characterAtIndex:i] != [init characterAtIndex:initIndex])

return false;

}

// We didn't match all of 'init'.

if (initIndex < [init length])

return false;

// If we're at the end or the next character is a capital letter then this is an init-family selector.

return i == [name length] || [[NSCharacterSet uppercaseLetterCharacterSet] characterIsMember:[name characterAtIndex:i]];

}

static bool shouldSkipMethodWithName(NSString *name)

{

// For clients that don't support init-based constructors just copy

// over the init method as we would have before.

if (!supportsInitMethodConstructors())

return false;

// Skip over init family methods because we handle those specially

// for the purposes of hooking up the constructor correctly.

return isInitFamilyMethod(name);

}

static void copyMethodsToObject(JSContext *context, Class objcClass, Protocol *protocol, BOOL isInstanceMethod, JSValue *object, NSMutableDictionary *accessorMethods = nil)

{

NSMutableDictionary *renameMap = createRenameMap(protocol, isInstanceMethod);

forEachMethodInProtocol(protocol, YES, isInstanceMethod, ^(SEL sel, const char* types){

const char* nameCStr = sel_getName(sel);

NSString *name = @(nameCStr);

if (shouldSkipMethodWithName(name))

return;

if (accessorMethods && accessorMethods[name]) {

JSObjectRef method = objCCallbackFunctionForMethod(context, objcClass, protocol, isInstanceMethod, sel, types);

if (!method)

return;

accessorMethods[name] = [JSValue valueWithJSValueRef:method inContext:context];

} else {

name = renameMap[name];

if (!name)

name = selectorToPropertyName(nameCStr);

JSC::JSGlobalObject* globalObject = toJS([context JSGlobalContextRef]);

JSValue *existingMethod = object[name];

// ObjCCallbackFunction does a dynamic lookup for the

// selector before calling the method. In order to save

// memory we only put one callback object in any givin

// prototype chain. However, to handle the client trying

// to override normal builtins e.g. "toString" we check if

// the existing value on the prototype chain is an ObjC

// callback already.

if ([existingMethod isObject] && JSC::jsDynamicCast<JSC::ObjCCallbackFunction*>(globalObject->vm(), toJS(globalObject, [existingMethod JSValueRef])))

return;

JSObjectRef method = objCCallbackFunctionForMethod(context, objcClass, protocol, isInstanceMethod, sel, types);

if (method)

putNonEnumerable(context, object, name, [JSValue valueWithJSValueRef:method inContext:context]);

}

});

[renameMap release];

}

struct Property {

const char* name;

RetainPtr<NSString> getterName;

RetainPtr<NSString> setterName;

};

static bool parsePropertyAttributes(objc_property_t objcProperty, Property& property)

{

bool readonly = false;

unsigned attributeCount;

auto attributes = adoptSystem<objc_property_attribute_t[]>(property_copyAttributeList(objcProperty, &attributeCount));

if (attributeCount) {

for (unsigned i = 0; i < attributeCount; ++i) {

switch (*(attributes[i].name)) {

case 'G':

property.getterName = @(attributes[i].value);

break;

case 'S':

property.setterName = @(attributes[i].value);

break;

case 'R':

readonly = true;

break;

default:

break;

}

}

}

return readonly;

}

static RetainPtr<NSString> makeSetterName(const char* name)

{

size_t nameLength = strlen(name);

// "set" Name ":\0" => nameLength + 5.

Vector<char, 128> buffer(nameLength + 5);

buffer[0] = 's';

buffer[1] = 'e';

buffer[2] = 't';

buffer[3] = toASCIIUpper(*name);

memcpy(buffer.data() + 4, name + 1, nameLength - 1);

buffer[nameLength + 3] = ':';

buffer[nameLength + 4] = '\0';

return @(buffer.data());

}

static void copyPrototypeProperties(JSContext *context, Class objcClass, Protocol *protocol, JSValue *prototypeValue)

{

// First gather propreties into this list, then handle the methods (capturing the accessor methods).

__block Vector<Property> propertyList;

// Map recording the methods used as getters/setters.

NSMutableDictionary *accessorMethods = [NSMutableDictionary dictionary];

// Useful value.

JSValue *undefined = [JSValue valueWithUndefinedInContext:context];

forEachPropertyInProtocol(protocol, ^(objc_property_t objcProperty) {

const char* name = property_getName(objcProperty);

Property property { name, nullptr, nullptr };

bool readonly = parsePropertyAttributes(objcProperty, property);

// Add the names of the getter & setter methods to

if (!property.getterName)

property.getterName = @(name);

accessorMethods[property.getterName.get()] = undefined;

if (!readonly) {

if (!property.setterName)

property.setterName = makeSetterName(name);

accessorMethods[property.setterName.get()] = undefined;

}

// Add the properties to a list.

propertyList.append(WTFMove(property));

});

// Copy methods to the prototype, capturing accessors in the accessorMethods map.

copyMethodsToObject(context, objcClass, protocol, YES, prototypeValue, accessorMethods);

// Iterate the propertyList & generate accessor properties.

for (auto& property : propertyList) {

JSValue* getter = accessorMethods[property.getterName.get()];

ASSERT(![getter isUndefined]);

JSValue* setter = undefined;

if (property.setterName) {

setter = accessorMethods[property.setterName.get()];

ASSERT(![setter isUndefined]);

}

[prototypeValue defineProperty:@(property.name) descriptor:@{

JSPropertyDescriptorGetKey: getter,

JSPropertyDescriptorSetKey: setter,

JSPropertyDescriptorEnumerableKey: @NO,

JSPropertyDescriptorConfigurableKey: @YES

}];

}

}

@interface JSObjCClassInfo : NSObject {

Class m_class;

bool m_block;

NakedPtr<OpaqueJSClass> m_classRef;

JSC::Weak<JSC::JSObject> m_prototype;

JSC::Weak<JSC::JSObject> m_constructor;

JSC::Weak<JSC::Structure> m_structure;

}

- (instancetype)initForClass:(Class)cls;

- (JSC::JSObject *)wrapperForObject:(id)object inContext:(JSContext *)context;

- (JSC::JSObject *)constructorInContext:(JSContext *)context;

- (JSC::JSObject *)prototypeInContext:(JSContext *)context;

@implementation JSObjCClassInfo

- (instancetype)initForClass:(Class)cls

{

self = [super init];

if (!self)

return nil;

const char* className = class_getName(cls);

m_class = cls;

m_block = [cls isSubclassOfClass:getNSBlockClass()];

JSClassDefinition definition;

definition = kJSClassDefinitionEmpty;

definition.className = className;

m_classRef = JSClassCreate(&definition);

return self;

}

- (void)dealloc

{

JSClassRelease(m_classRef.get());

[super dealloc];

}

static JSC::JSObject* allocateConstructorForCustomClass(JSContext *context, const char* className, Class cls)

{

if (!supportsInitMethodConstructors())

return constructorWithCustomBrand(context, [NSString stringWithFormat:@"%sConstructor", className], cls);

// For each protocol that the class implements, gather all of the init family methods into a hash table.

__block HashMap<String, CFTypeRef> initTable;

Protocol *exportProtocol = getJSExportProtocol();

for (Class currentClass = cls; currentClass; currentClass = class_getSuperclass(currentClass)) {

forEachProtocolImplementingProtocol(currentClass, exportProtocol, ^(Protocol *protocol, bool&) {

forEachMethodInProtocol(protocol, YES, YES, ^(SEL selector, const char*) {

const char* name = sel_getName(selector);

if (!isInitFamilyMethod(@(name)))

return;

initTable.set(name, (__bridge CFTypeRef)protocol);

});

});

}

for (Class currentClass = cls; currentClass; currentClass = class_getSuperclass(currentClass)) {

__block unsigned numberOfInitsFound = 0;

__block SEL initMethod = 0;

__block Protocol *initProtocol = 0;

__block const char* types = 0;

forEachMethodInClass(currentClass, ^(Method method) {

SEL selector = method_getName(method);

const char* name = sel_getName(selector);

auto iter = initTable.find(name);

if (iter == initTable.end())

return;

numberOfInitsFound++;

initMethod = selector;

initProtocol = (__bridge Protocol *)iter->value;

types = method_getTypeEncoding(method);

});

if (!numberOfInitsFound)

continue;

if (numberOfInitsFound > 1) {

NSLog(@"ERROR: Class %@ exported more than one init family method via JSExport. Class %@ will not have a callable JavaScript constructor function.", cls, cls);

break;

}

JSObjectRef method = objCCallbackFunctionForInit(context, cls, initProtocol, initMethod, types);

return toJS(method);

}

return constructorWithCustomBrand(context, [NSString stringWithFormat:@"%sConstructor", className], cls);

}

typedef std::pair<JSC::JSObject*, JSC::JSObject*> ConstructorPrototypePair;

- (ConstructorPrototypePair)allocateConstructorAndPrototypeInContext:(JSContext *)context

{

JSObjCClassInfo* superClassInfo = [context.wrapperMap classInfoForClass:class_getSuperclass(m_class)];

ASSERT(!m_constructor || !m_prototype);

ASSERT((m_class == [NSObject class]) == !superClassInfo);

JSC::JSObject* jsPrototype = m_prototype.get();

JSC::JSObject* jsConstructor = m_constructor.get();

if (!superClassInfo) {

JSC::JSGlobalObject* globalObject = toJSGlobalObject([context JSGlobalContextRef]);

if (!jsConstructor)

jsConstructor = globalObject->objectConstructor();

if (!jsPrototype)

jsPrototype = globalObject->objectPrototype();

} else {

const char* className = class_getName(m_class);

// Create or grab the prototype/constructor pair.

if (!jsPrototype)

jsPrototype = objectWithCustomBrand(context, [NSString stringWithFormat:@"%sPrototype", className]);

if (!jsConstructor)

jsConstructor = allocateConstructorForCustomClass(context, className, m_class);

JSValue* prototype = [JSValue valueWithJSValueRef:toRef(jsPrototype) inContext:context];

JSValue* constructor = [JSValue valueWithJSValueRef:toRef(jsConstructor) inContext:context];

putNonEnumerable(context, prototype, @"constructor", constructor);

putNonEnumerable(context, constructor, @"prototype", prototype);

Protocol *exportProtocol = getJSExportProtocol();

forEachProtocolImplementingProtocol(m_class, exportProtocol, ^(Protocol *protocol, bool&){

copyPrototypeProperties(context, m_class, protocol, prototype);

copyMethodsToObject(context, m_class, protocol, NO, constructor);

});

// Set [Prototype].

JSC::JSObject* superClassPrototype = [superClassInfo prototypeInContext:context];

JSObjectSetPrototype([context JSGlobalContextRef], toRef(jsPrototype), toRef(superClassPrototype));

}

m_prototype = jsPrototype;

m_constructor = jsConstructor;

return ConstructorPrototypePair(jsConstructor, jsPrototype);

}

- (JSC::JSObject*)wrapperForObject:(id)object inContext:(JSContext *)context

{

ASSERT([object isKindOfClass:m_class]);

ASSERT(m_block == [object isKindOfClass:getNSBlockClass()]);

if (m_block) {

if (JSObjectRef method = objCCallbackFunctionForBlock(context, object)) {

JSValue *constructor = [JSValue valueWithJSValueRef:method inContext:context];

JSValue *prototype = [JSValue valueWithNewObjectInContext:context];

putNonEnumerable(context, constructor, @"prototype", prototype);

putNonEnumerable(context, prototype, @"constructor", constructor);

return toJS(method);

}

}

JSC::Structure* structure = [self structureInContext:context];

JSC::JSGlobalObject* globalObject = toJS([context JSGlobalContextRef]);

JSC::VM& vm = globalObject->vm();

JSC::JSLockHolder locker(vm);

auto wrapper = JSC::JSCallbackObject<JSC::JSAPIWrapperObject>::create(globalObject, structure, m_classRef, 0);

wrapper->setWrappedObject((__bridge void*)object);

return wrapper;

}

- (JSC::JSObject*)constructorInContext:(JSContext *)context

{

JSC::JSObject* constructor = m_constructor.get();

if (!constructor)

constructor = [self allocateConstructorAndPrototypeInContext:context].first;

ASSERT(!!constructor);

return constructor;

}

- (JSC::JSObject*)prototypeInContext:(JSContext *)context

{

JSC::JSObject* prototype = m_prototype.get();

if (!prototype)

prototype = [self allocateConstructorAndPrototypeInContext:context].second;

ASSERT(!!prototype);

return prototype;

}

- (JSC::Structure*)structureInContext:(JSContext *)context

{

JSC::Structure* structure = m_structure.get();

if (structure)

return structure;

JSC::JSGlobalObject* globalObject = toJSGlobalObject([context JSGlobalContextRef]);

JSC::JSObject* prototype = [self prototypeInContext:context];

m_structure = JSC::JSCallbackObject<JSC::JSAPIWrapperObject>::createStructure(globalObject->vm(), globalObject, prototype);

return m_structure.get();

}

@implementation JSWrapperMap {

NSMutableDictionary *m_classMap;

std::unique_ptr<JSC::WeakGCMap<__unsafe_unretained id, JSC::JSObject>> m_cachedJSWrappers;

NSMapTable *m_cachedObjCWrappers;

}

- (instancetype)initWithGlobalContextRef:(JSGlobalContextRef)context

{

self = [super init];

if (!self)

return nil;

NSPointerFunctionsOptions keyOptions = NSPointerFunctionsOpaqueMemory | NSPointerFunctionsOpaquePersonality;

NSPointerFunctionsOptions valueOptions = NSPointerFunctionsWeakMemory | NSPointerFunctionsObjectPersonality;

m_cachedObjCWrappers = [[NSMapTable alloc] initWithKeyOptions:keyOptions valueOptions:valueOptions capacity:0];

m_cachedJSWrappers = makeUnique<JSC::WeakGCMap<__unsafe_unretained id, JSC::JSObject>>(toJS(context)->vm());

ASSERT(!toJSGlobalObject(context)->wrapperMap());

toJSGlobalObject(context)->setWrapperMap(self);

m_classMap = [[NSMutableDictionary alloc] init];

return self;

}

- (void)dealloc

{

[m_cachedObjCWrappers release];

[m_classMap release];

[super dealloc];

}

- (JSObjCClassInfo*)classInfoForClass:(Class)cls

{

if (!cls)

return nil;

// Check if we've already created a JSObjCClassInfo for this Class.

if (JSObjCClassInfo* classInfo = (JSObjCClassInfo*)m_classMap[cls])

return classInfo;

// Skip internal classes beginning with '_' - just copy link to the parent class's info.

if ('_' == *class_getName(cls)) {

bool conformsToExportProtocol = false;

forEachProtocolImplementingProtocol(cls, getJSExportProtocol(), [&conformsToExportProtocol](Protocol *, bool& stop) {

conformsToExportProtocol = true;

stop = true;

});

if (!conformsToExportProtocol)

return m_classMap[cls] = [self classInfoForClass:class_getSuperclass(cls)];

}

return m_classMap[cls] = [[[JSObjCClassInfo alloc] initForClass:cls] autorelease];

}

- (JSValue *)jsWrapperForObject:(id)object inContext:(JSContext *)context

{

ASSERT(toJSGlobalObject([context JSGlobalContextRef])->wrapperMap() == self);

JSC::JSObject* jsWrapper = m_cachedJSWrappers->get(object);

if (jsWrapper)

return [JSValue valueWithJSValueRef:toRef(jsWrapper) inContext:context];

if (class_isMetaClass(object_getClass(object)))

jsWrapper = [[self classInfoForClass:(Class)object] constructorInContext:context];

else {

JSObjCClassInfo* classInfo = [self classInfoForClass:[object class]];

jsWrapper = [classInfo wrapperForObject:object inContext:context];

}

// FIXME: https://bugs.webkit.org/show_bug.cgi?id=105891

// This general approach to wrapper caching is pretty effective, but there are a couple of problems:

// (1) For immortal objects JSValues will effectively leak and this results in error output being logged - we should avoid adding associated objects to immortal objects.

// (2) A long lived object may rack up many JSValues. When the contexts are released these will unprotect the associated JavaScript objects,

// but still, would probably nicer if we made it so that only one associated object was required, broadcasting object dealloc.

m_cachedJSWrappers->set(object, jsWrapper);

return [JSValue valueWithJSValueRef:toRef(jsWrapper) inContext:context];

}

- (JSValue *)objcWrapperForJSValueRef:(JSValueRef)value inContext:context

{

ASSERT(toJSGlobalObject([context JSGlobalContextRef])->wrapperMap() == self);

JSValue *wrapper = (__bridge JSValue *)NSMapGet(m_cachedObjCWrappers, value);

if (!wrapper) {

wrapper = [[[JSValue alloc] initWithValue:value inContext:context] autorelease];

NSMapInsert(m_cachedObjCWrappers, value, (__bridge void*)wrapper);

}

return wrapper;

}

id tryUnwrapObjcObject(JSGlobalContextRef context, JSValueRef value)

{

if (!JSValueIsObject(context, value))

return nil;

JSValueRef exception = 0;

JSObjectRef object = JSValueToObject(context, value, &exception);

ASSERT(!exception);

JSC::JSLockHolder locker(toJS(context));

JSC::VM& vm = toJS(context)->vm();

if (toJS(object)->inherits<JSC::JSCallbackObject<JSC::JSAPIWrapperObject>>(vm))

return (__bridge id)JSC::jsCast<JSC::JSAPIWrapperObject*>(toJS(object))->wrappedObject();

if (id class="pl-c1">tryUnwrapConstructor(&vm, object))

return target;

return nil;

}

NS_ROOT_CLASS @interface JSExport <JSExport>

@implementation JSExport

bool supportsInitMethodConstructors()

{

#if PLATFORM(APPLETV)

// There are no old clients on Apple TV, so there's no need for backwards compatibility.

return true;

#else

// First check to see the version of JavaScriptCore we directly linked against.

static int32_t versionOfLinkTimeJavaScriptCore = 0;

if (!versionOfLinkTimeJavaScriptCore)

versionOfLinkTimeJavaScriptCore = NSVersionOfLinkTimeLibrary("JavaScriptCore");

// Only do the link time version comparison if we linked directly with JavaScriptCore

if (versionOfLinkTimeJavaScriptCore != -1)

return versionOfLinkTimeJavaScriptCore >= firstJavaScriptCoreVersionWithInitConstructorSupport;

// If we didn't link directly with JavaScriptCore,

// base our check on what SDK was used to build the application.

static uint32_t programSDKVersion = 0;

if (!programSDKVersion)

programSDKVersion = dyld_get_program_sdk_version();

return programSDKVersion >= firstSDKVersionWithInitConstructorSupport;

#endif

}

Protocol *getJSExportProtocol()

{

static Protocol *protocol = objc_getProtocol("JSExport");

return protocol;

}

Class getNSBlockClass()

{

static Class cls = objc_getClass("NSBlock");

return cls;

}

#endif