BC Soft Errors

Reviewed By: javache

Differential Revision: D4131340

fbshipit-source-id: b0827fc99d94985fbbb2a1b03ddc4d6feab10bff

React/Base/RCTJavaScriptLoader.h

@@ -24,25 +24,33 @@ typedef NS_ENUM(NSInteger) {
 } RCTScriptTag;
 
 /**
- * RCTMagicNumber
+ * RCTBundleHeader
  *
- * RAM bundles and BC bundles begin with magic numbers. For RAM bundles this is
+ * RAM bundles and BC bundles begin with headers. For RAM bundles this is
- * 4 bytes, for BC bundles this is 8 bytes. This structure holds the first 8
+ * 4 bytes, for BC bundles this is 12 bytes. This structure holds the first 12
  * bytes from a bundle in a way that gives access to that information.
  */
 typedef union {
-  uint64_t allBytes;
+  // `allBytes` is the first field so that zero-initializing the union fills
-  uint32_t first4;
+  // it completely with zeroes. Without it, only the first field of the union
-  uint64_t first8;
+  // gets zero-initialized.
-} RCTMagicNumber;
+  uint32_t allBytes[3];
+
+  uint32_t RAMMagic;
+
+  struct {
+    uint64_t BCMagic;
+    uint32_t BCVersion;
+  };
+} RCTBundleHeader;
 
 /**
- * RCTParseMagicNumber
+ * RCTParseTypeFromHeader
  *
  * Takes the first 8 bytes of a bundle, and returns a tag describing the
  * bundle's format.
  */
-RCT_EXTERN RCTScriptTag RCTParseMagicNumber(RCTMagicNumber magic);
+RCT_EXTERN RCTScriptTag RCTParseTypeFromHeader(RCTBundleHeader header);
 
 extern NSString *const RCTJavaScriptLoaderErrorDomain;
 
@@ -52,6 +60,7 @@ NS_ENUM(NSInteger) {
   RCTJavaScriptLoaderErrorFailedReadingFile = 3,
   RCTJavaScriptLoaderErrorFailedStatingFile = 3,
   RCTJavaScriptLoaderErrorURLLoadFailed = 3,
+  RCTJavaScriptLoaderErrorBCVersion = 4,
 
   RCTJavaScriptLoaderErrorCannotBeLoadedSynchronously = 1000,
 };
@@ -80,6 +89,7 @@ typedef void (^RCTSourceLoadBlock)(NSError *error, NSData *source, int64_t sourc
  * RCTJavaScriptLoaderErrorDomain and the code RCTJavaScriptLoaderErrorCannotBeLoadedSynchronously.
  */
 + (NSData *)attemptSynchronousLoadOfBundleAtURL:(NSURL *)scriptURL
+                               runtimeBCVersion:(int32_t)runtimeBCVersion
                                    sourceLength:(int64_t *)sourceLength
                                           error:(NSError **)error;
 

React/Base/RCTJavaScriptLoader.m

@@ -11,6 +11,7 @@
 
 #import "RCTBridge.h"
 #import "RCTConvert.h"
+#import "RCTJSCWrapper.h"
 #import "RCTSourceCode.h"
 #import "RCTUtils.h"
 #import "RCTPerformanceLogger.h"
@@ -23,13 +24,13 @@ static uint64_t const RCTBCBundleMagicNumber  = 0xFF4865726D657300;
 
 NSString *const RCTJavaScriptLoaderErrorDomain = @"RCTJavaScriptLoaderErrorDomain";
 
-RCTScriptTag RCTParseMagicNumber(RCTMagicNumber magic)
+RCTScriptTag RCTParseTypeFromHeader(RCTBundleHeader header)
 {
-  if (NSSwapLittleIntToHost(magic.first4) == RCTRAMBundleMagicNumber) {
+  if (NSSwapLittleIntToHost(header.RAMMagic) == RCTRAMBundleMagicNumber) {
     return RCTScriptRAMBundle;
   }
 
-  if (NSSwapLittleLongLongToHost(magic.first8) == RCTBCBundleMagicNumber) {
+  if (NSSwapLittleLongLongToHost(header.BCMagic) == RCTBCBundleMagicNumber) {
     return RCTScriptBCBundle;
   }
 
@@ -61,6 +62,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
   int64_t sourceLength;
   NSError *error;
   NSData *data = [self attemptSynchronousLoadOfBundleAtURL:scriptURL
+                                          runtimeBCVersion:JSNoBytecodeFileFormatVersion
                                               sourceLength:&sourceLength
                                                      error:&error];
   if (data) {
@@ -80,6 +82,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
 }
 
 + (NSData *)attemptSynchronousLoadOfBundleAtURL:(NSURL *)scriptURL
+                               runtimeBCVersion:(int32_t)runtimeBCVersion
                                    sourceLength:(int64_t *)sourceLength
                                           error:(NSError **)error
 {
@@ -126,8 +129,8 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
     return nil;
   }
 
-  RCTMagicNumber magicNumber = {.allBytes = 0};
+  RCTBundleHeader header = {};
-  size_t readResult = fread(&magicNumber, sizeof(magicNumber), 1, bundle);
+  size_t readResult = fread(&header, sizeof(header), 1, bundle);
   fclose(bundle);
   if (readResult != 1) {
     if (error) {
@@ -139,8 +142,12 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
     return nil;
   }
 
-  RCTScriptTag tag = RCTParseMagicNumber(magicNumber);
+  RCTScriptTag tag = RCTParseTypeFromHeader(header);
-  if (tag == RCTScriptString) {
+  switch (tag) {
+  case RCTScriptRAMBundle:
+    break;
+
+  case RCTScriptString:
     if (error) {
       *error = [NSError errorWithDomain:RCTJavaScriptLoaderErrorDomain
                                    code:RCTJavaScriptLoaderErrorCannotBeLoadedSynchronously
@@ -148,6 +155,21 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
                                             @"Cannot load text/javascript files synchronously"}];
     }
     return nil;
+
+  case RCTScriptBCBundle:
+    if (header.BCVersion != runtimeBCVersion) {
+      if (error) {
+        NSString *errDesc =
+          [NSString stringWithFormat:@"BC Version Mismatch. Expect: %d, Actual: %d",
+                    runtimeBCVersion, header.BCVersion];
+
+        *error = [NSError errorWithDomain:RCTJavaScriptLoaderErrorDomain
+                                     code:RCTJavaScriptLoaderErrorBCVersion
+                                 userInfo:@{NSLocalizedDescriptionKey: errDesc}];
+      }
+      return nil;
+    }
+    break;
   }
 
   struct stat statInfo;
@@ -163,7 +185,7 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
   if (sourceLength) {
     *sourceLength = statInfo.st_size;
   }
-  return [NSData dataWithBytes:&magicNumber length:sizeof(magicNumber)];
+  return [NSData dataWithBytes:&header length:sizeof(header)];
 }
 
 static void attemptAsynchronousLoadOfBundleAtURL(NSURL *scriptURL, RCTSourceLoadProgressBlock onProgress, RCTSourceLoadBlock onComplete)

React/Executors/RCTJSCExecutor.h

@@ -72,6 +72,11 @@ RCT_EXTERN NSString *const RCTFBJSValueClassKey;
  */
 @property (nonatomic, readonly, assign) BOOL useCustomJSCLibrary;
 
+/**
+ * Returns the bytecode file format that the underlying runtime supports.
+ */
+@property (nonatomic, readonly) int32_t bytecodeFileFormatVersion;
+
 /**
  * Specify a name for the JSContext used, which will be visible in debugging tools
  * @default is "RCTJSContext"

React/Executors/RCTJSCExecutor.mm

@@ -500,6 +500,11 @@ static void installBasicSynchronousHooksOnContext(JSContext *context)
 #endif
 }
 
+- (int32_t)bytecodeFileFormatVersion
+{
+  return _jscWrapper->JSBytecodeFileFormatVersion;
+}
+
 - (NSString *)contextName
 {
   return [_context.context name];
@@ -688,9 +693,9 @@ static TaggedScript loadTaggedScript(NSData *script,
 {
   RCT_PROFILE_BEGIN_EVENT(0, @"executeApplicationScript / prepare bundle", nil);
 
-  RCTMagicNumber magicNumber = {.allBytes = 0};
+  RCTBundleHeader header = {};
-  [script getBytes:&magicNumber length:sizeof(magicNumber)];
+  [script getBytes:&header length:sizeof(header)];
-  RCTScriptTag tag = RCTParseMagicNumber(magicNumber);
+  RCTScriptTag tag = RCTParseTypeFromHeader(header);
 
   NSData *loadedScript = NULL;
   switch (tag) {

React/Executors/RCTJSCWrapper.mm

@@ -74,9 +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],
   };