Setting runtime options for JSC on iOS

Reviewed By: michalgr

Differential Revision: D4104084

fbshipit-source-id: 517f833343948c59e5f77cede8a60574ca1e40c0

React/Executors/RCTJSCExecutor.mm

@@ -339,6 +339,7 @@ static NSThread *newJavaScriptThread(void)
       [self->_performanceLogger markStopForTag:RCTPLJSCWrapperOpenLibrary];
 
       RCTAssert(self->_context == nil, @"Didn't expect to set up twice");
+      self->_jscWrapper->configureJSCForIOS();
       context = [self->_jscWrapper->JSContext new];
       self->_context = [[RCTJavaScriptContext alloc] initWithJSContext:context onThread:self->_javaScriptThread];
       [[NSNotificationCenter defaultCenter] postNotificationName:RCTJavaScriptContextCreatedNotification
@@ -990,6 +991,7 @@ static NSData *loadRAMBundle(NSURL *sourceURL, NSError **error, RandomAccessBund
 - (void)_createContext
 {
   _jscWrapper = RCTJSCWrapperCreate(_useCustomJSCLibrary);
+  _jscWrapper->configureJSCForIOS();
   _context = [_jscWrapper->JSContext new];
   installBasicSynchronousHooksOnContext(_context);
   dispatch_semaphore_signal(_semaphore);

React/Executors/RCTJSCWrapper.h

@@ -11,6 +11,7 @@
 
 #import "RCTDefines.h"
 
+typedef void (*voidWithNoParamsFuncType)();
 typedef JSStringRef (*JSStringCreateWithCFStringFuncType)(CFStringRef);
 typedef JSStringRef (*JSStringCreateWithUTF8CStringFuncType)(const char *);
 typedef void (*JSStringReleaseFuncType)(JSStringRef);
@@ -50,6 +51,7 @@ typedef struct RCTJSCWrapper {
   JSValueIsNullFuncType JSValueIsNull;
   JSEvaluateScriptFuncType JSEvaluateScript;
   JSEvaluateBytecodeBundleFuncType JSEvaluateBytecodeBundle;
+  voidWithNoParamsFuncType configureJSCForIOS;
   const int32_t JSBytecodeFileFormatVersion;
   Class JSContext;
   Class JSValue;

React/Executors/RCTJSCWrapper.mm

@@ -27,6 +27,10 @@ UNIMPLEMENTED_SYSTEM_JSC_FUNCTION(JSEvaluateBytecodeBundle)
 
 #undef UNIMPLEMENTED_SYSTEM_JSC_FUNCTION
 
+// A no-op function, to replace void functions that do no exist in the system JSC
+//  with a function that does nothing.
+static void noOpSystemJSCFunc(void *args...){ }
+
 void __attribute__((visibility("hidden"),weak)) RCTCustomJSCInit(__unused void *handle) {
   return;
 }
@@ -70,8 +74,9 @@ static RCTJSCWrapper *RCTSetUpSystemLibraryPointers()
     .JSValueIsUndefined = JSValueIsUndefined,
     .JSValueIsNull = JSValueIsNull,
     .JSEvaluateScript = JSEvaluateScript,
-    .JSBytecodeFileFormatVersion = JSNoBytecodeFileFormatVersion,
     .JSEvaluateBytecodeBundle = (JSEvaluateBytecodeBundleFuncType)UnimplementedJSEvaluateBytecodeBundle,
+    .configureJSCForIOS = (voidWithNoParamsFuncType)noOpSystemJSCFunc,
+    .JSBytecodeFileFormatVersion = JSNoBytecodeFileFormatVersion,
     .JSContext = [JSContext class],
     .JSValue = [JSValue class],
   };
@@ -100,6 +105,7 @@ static RCTJSCWrapper *RCTSetUpCustomLibraryPointers()
     .JSValueIsNull = (JSValueIsNullFuncType)dlsym(libraryHandle, "JSValueIsNull"),
     .JSEvaluateScript = (JSEvaluateScriptFuncType)dlsym(libraryHandle, "JSEvaluateScript"),
     .JSEvaluateBytecodeBundle = (JSEvaluateBytecodeBundleFuncType)dlsym(libraryHandle, "JSEvaluateBytecodeBundle"),
+    .configureJSCForIOS = (voidWithNoParamsFuncType)dlsym(libraryHandle, "configureJSCForIOS"),
     .JSBytecodeFileFormatVersion = *(const int32_t *)dlsym(libraryHandle, "JSBytecodeFileFormatVersion"),
     .JSContext = (__bridge Class)dlsym(libraryHandle, "OBJC_CLASS_$_JSContext"),
     .JSValue = (__bridge Class)dlsym(libraryHandle, "OBJC_CLASS_$_JSValue"),