1 files changed, 37 insertions, 11 deletions

diff --git a/lib/internal/bootstrap/loaders.js b/lib/internal/bootstrap/loaders.js
index e85d5de9b7..c04a4207c0 100644
--- a/lib/internal/bootstrap/loaders.js
+++ b/lib/internal/bootstrap/loaders.js
@@ -127,6 +127,8 @@
   const config = getBinding('config');
 
   const codeCache = getInternalBinding('code_cache');
+  const codeCacheHash = getInternalBinding('code_cache_hash');
+  const sourceHash = getInternalBinding('natives_hash');
   const compiledWithoutCache = NativeModule.compiledWithoutCache = [];
   const compiledWithCache = NativeModule.compiledWithCache = [];
 
@@ -232,32 +234,56 @@
   };
 
   NativeModule.prototype.compile = function() {
-    let source = NativeModule.getSource(this.id);
+    const id = this.id;
+    let source = NativeModule.getSource(id);
     source = NativeModule.wrap(source);
 
     this.loading = true;
 
     try {
+      // Currently V8 only checks that the length of the source code is the
+      // same as the code used to generate the hash, so we add an additional
+      // check here:
+      // 1. During compile time, when generating node_javascript.cc and
+      //    node_code_cache.cc, we compute and include the hash of the
+      //   (unwrapped) JavaScript source in both.
+      // 2. At runtime, we check that the hash of the code being compiled
+      //   and the hash of the code used to generate the cache
+      //   (inside the wrapper) is the same.
+      // This is based on the assumptions:
+      // 1. `internalBinding('code_cache_hash')` must be in sync with
+      //    `internalBinding('code_cache')` (same C++ file)
+      // 2. `internalBinding('natives_hash')` must be in sync with
+      //    `process.binding('natives')` (same C++ file)
+      // 3. If `internalBinding('natives_hash')` is in sync with
+      //    `internalBinding('natives_hash')`, then the (unwrapped)
+      //    code used to generate `internalBinding('code_cache')`
+      //    should be in sync with the (unwrapped) code in
+      //    `process.binding('natives')`
+      // There will be, however, false positives if the wrapper used
+      // to generate the cache is different from the one used at run time,
+      // and the length of the wrapper somehow stays the same.
+      // But that should be rare and can be eased once we make the
+      // two bootstrappers cached and checked as well.
+      const cache = codeCacheHash[id] &&
+        (codeCacheHash[id] === sourceHash[id]) ? codeCache[id] : undefined;
+
       // (code, filename, lineOffset, columnOffset
       // cachedData, produceCachedData, parsingContext)
       const script = new ContextifyScript(
         source, this.filename, 0, 0,
-        codeCache[this.id], false, undefined
+        cache, false, undefined
       );
 
+      // This will be used to create code cache in tools/generate_code_cache.js
       this.script = script;
 
       // One of these conditions may be false when any of the inputs
       // of the `node_js2c` target in node.gyp is modified.
-      // FIXME(joyeecheung):
-      // 1. Figure out how to resolve the dependency issue. When the
-      //    code cache was introduced we were at a point where refactoring
-      //    node.gyp may not be worth the effort.
-      // 2. Calculate checksums in both js2c and generate_code_cache.js
-      //    and compare them before compiling the native modules since
-      //    V8 only checks the length of the source to decide whether to
-      //    reject the cache.
-      if (!codeCache[this.id] || script.cachedDataRejected) {
+      // FIXME(joyeecheung): Figure out how to resolve the dependency issue.
+      // When the code cache was introduced we were at a point where refactoring
+      // node.gyp may not be worth the effort.
+      if (!cache || script.cachedDataRejected) {
         compiledWithoutCache.push(this.id);
       } else {
         compiledWithCache.push(this.id);