deps: backport 1f8555 from v8's upstream

Original commit message: api: introduce SealHandleScope When debugging Handle leaks in io.js we found it very convenient to be able to Seal some specific (root in our case) scope to prevent Handle allocations in it, and easily find leakage. R=yangguo BUG= Review URL: https://codereview.chromium.org/1079713002 Cr-Commit-Position: refs/heads/master@{#27766} Should help us identify and fix Handle leaks in core and user-space code. PR-URL: #3945 Reviewed-By: Fedor Indutny <[email protected]> Reviewed-By: James Snell <[email protected]>
nodejs · Dec 4, 2015 · fbc8cd9 · fbc8cd9
1 parent cf98211
commit fbc8cd9
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Showing 5 changed files with 76 additions and 4 deletions.
diff --git a/deps/v8/include/v8.h b/deps/v8/include/v8.h
@@ -944,6 +944,27 @@ class ScriptOrigin {
 };
 
 
+class V8_EXPORT SealHandleScope {
+ public:
+  SealHandleScope(Isolate* isolate);
+  ~SealHandleScope();
+
+ private:
+  // Make it hard to create heap-allocated or illegal handle scopes by
+  // disallowing certain operations.
+  SealHandleScope(const SealHandleScope&);
+  void operator=(const SealHandleScope&);
+  void* operator new(size_t size);
+  void operator delete(void*, size_t);
+
+  internal::Isolate* isolate_;
+  int prev_level_;
+  internal::Object** prev_limit_;
+};
+
+
+
+
 /**
  * A compiled JavaScript script, not yet tied to a Context.
  */

diff --git a/deps/v8/src/api.cc b/deps/v8/src/api.cc
@@ -637,6 +637,27 @@ i::Object** EscapableHandleScope::Escape(i::Object** escape_value) {
 }
 
 
+SealHandleScope::SealHandleScope(Isolate* isolate) {
+  i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate);
+
+  isolate_ = internal_isolate;
+  i::HandleScopeData* current = internal_isolate->handle_scope_data();
+  prev_limit_ = current->limit;
+  current->limit = current->next;
+  prev_level_ = current->level;
+  current->level = 0;
+}
+
+
+SealHandleScope::~SealHandleScope() {
+  i::HandleScopeData* current = isolate_->handle_scope_data();
+  DCHECK_EQ(0, current->level);
+  current->level = prev_level_;
+  DCHECK_EQ(current->next, current->limit);
+  current->limit = prev_limit_;
+}
+
+
 void Context::Enter() {
   i::Handle<i::Context> env = Utils::OpenHandle(this);
   i::Isolate* isolate = env->GetIsolate();

diff --git a/deps/v8/src/api.h b/deps/v8/src/api.h
@@ -642,17 +642,14 @@ void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {
   while (!blocks_.is_empty()) {
     internal::Object** block_start = blocks_.last();
     internal::Object** block_limit = block_start + kHandleBlockSize;
-#ifdef DEBUG
+
     // SealHandleScope may make the prev_limit to point inside the block.
     if (block_start <= prev_limit && prev_limit <= block_limit) {
 #ifdef ENABLE_HANDLE_ZAPPING
       internal::HandleScope::ZapRange(prev_limit, block_limit);
 #endif
       break;
     }
-#else
-    if (prev_limit == block_limit) break;
-#endif
 
     blocks_.RemoveLast();
 #ifdef ENABLE_HANDLE_ZAPPING

diff --git a/deps/v8/test/cctest/cctest.status b/deps/v8/test/cctest/cctest.status
@@ -43,6 +43,7 @@
   # they don't fail then test.py has failed.
   'test-serialize/TestThatAlwaysFails': [FAIL],
   'test-serialize/DependentTestThatAlwaysFails': [FAIL],
+  'test-api/SealHandleScope': [FAIL],
 
   # This test always fails.  It tests that LiveEdit causes abort when turned off.
   'test-debug/LiveEditDisabled': [FAIL],

diff --git a/deps/v8/test/cctest/test-api.cc b/deps/v8/test/cctest/test-api.cc
@@ -20625,6 +20625,38 @@ void CallCompletedCallbackException() {
 }
 
 
+TEST(SealHandleScope) {
+  v8::Isolate* isolate = CcTest::isolate();
+  v8::HandleScope handle_scope(isolate);
+  LocalContext env;
+
+  v8::SealHandleScope seal(isolate);
+
+  // Should fail
+  v8::Local<v8::Object> obj = v8::Object::New(isolate);
+
+  USE(obj);
+}
+
+
+TEST(SealHandleScopeNested) {
+  v8::Isolate* isolate = CcTest::isolate();
+  v8::HandleScope handle_scope(isolate);
+  LocalContext env;
+
+  v8::SealHandleScope seal(isolate);
+
+  {
+    v8::HandleScope handle_scope(isolate);
+
+    // Should work
+    v8::Local<v8::Object> obj = v8::Object::New(isolate);
+
+    USE(obj);
+  }
+}
+
+
 TEST(CallCompletedCallbackOneException) {
   LocalContext env;
   v8::HandleScope scope(env->GetIsolate());