Assert no VM handles are created in the zone that belongs to a ApiNativeScopes.

runtime/vm/snapshot_test.cc

Index: runtime/vm/snapshot_test.cc
diff --git a/runtime/vm/snapshot_test.cc b/runtime/vm/snapshot_test.cc
index e4f682946d0553ee858af6341da86e6c9d4adf35..2604914235b0c463aa9a1c9a802a6b88f46d4013 100644
--- a/runtime/vm/snapshot_test.cc
+++ b/runtime/vm/snapshot_test.cc
@@ -241,13 +241,17 @@ Dart_CObject* SerializeAndDeserializeMint(const Mint& mint) {
   writer.WriteMessage(mint);
   intptr_t buffer_len = writer.BytesWritten();
 
-  // Read object back from the snapshot.
-  MessageSnapshotReader reader(buffer,
-                               buffer_len,
-                               Isolate::Current(),
-                               Thread::Current()->zone());
-  const Object& serialized_object = Object::Handle(reader.ReadObject());
-  EXPECT(serialized_object.IsMint());
+  {
+    // Switch to a regular zone, where VM handle allocation is allowed.
+    StackZone zone(Isolate::Current());
+    // Read object back from the snapshot.
+    MessageSnapshotReader reader(buffer,
+                                 buffer_len,
+                                 Isolate::Current(),
+                                 Thread::Current()->zone());
+    const Object& serialized_object = Object::Handle(reader.ReadObject());
+    EXPECT(serialized_object.IsMint());
+  }
 
   // Read object back from the snapshot into a C structure.
   ApiMessageReader api_reader(buffer, buffer_len, &zone_allocator);
@@ -441,18 +445,22 @@ Dart_CObject* SerializeAndDeserializeBigint(const Bigint& bigint) {
   writer.WriteMessage(bigint);
   intptr_t buffer_len = writer.BytesWritten();
 
-  // Read object back from the snapshot.
-  MessageSnapshotReader reader(buffer,
-                               buffer_len,
-                               Isolate::Current(),
-                               Thread::Current()->zone());
-  Bigint& serialized_bigint = Bigint::Handle();
-  serialized_bigint ^= reader.ReadObject();
-  const char* str1 = bigint.ToHexCString(allocator);
-  const char* str2 = serialized_bigint.ToHexCString(allocator);
-  EXPECT_STREQ(str1, str2);
-  free(const_cast<char*>(str1));
-  free(const_cast<char*>(str2));
+  {
+    // Switch to a regular zone, where VM handle allocation is allowed.
+    StackZone zone(Isolate::Current());
+    // Read object back from the snapshot.
+    MessageSnapshotReader reader(buffer,
+                                 buffer_len,
+                                 Isolate::Current(),
+                                 Thread::Current()->zone());
+    Bigint& serialized_bigint = Bigint::Handle();
+    serialized_bigint ^= reader.ReadObject();
+    const char* str1 = bigint.ToHexCString(allocator);
+    const char* str2 = serialized_bigint.ToHexCString(allocator);
+    EXPECT_STREQ(str1, str2);
+    free(const_cast<char*>(str1));
+    free(const_cast<char*>(str2));
+  }
 
   // Read object back from the snapshot into a C structure.
   ApiMessageReader api_reader(buffer, buffer_len, &zone_allocator);
@@ -466,10 +474,9 @@ Dart_CObject* SerializeAndDeserializeBigint(const Bigint& bigint) {
 
 void CheckBigint(const char* bigint_value) {
   StackZone zone(Isolate::Current());
-  ApiNativeScope scope;
-
   Bigint& bigint = Bigint::Handle();
   bigint ^= Bigint::NewFromCString(bigint_value);
+  ApiNativeScope scope;
   Dart_CObject* bigint_cobject = SerializeAndDeserializeBigint(bigint);
   EXPECT_EQ(Dart_CObject_kBigint, bigint_cobject->type);
   char* hex_value = TestCase::BigintToHexValue(bigint_cobject);
@@ -1588,7 +1595,8 @@ TEST_CASE(IntArrayMessage) {
 // Helper function to call a top level Dart function, serialize the
 // result and deserialize the result into a Dart_CObject structure.
 static Dart_CObject* GetDeserializedDartMessage(Dart_Handle lib,
-                                                const char* dart_function) {
+                                                const char* dart_function,
+                                                Object* tmp_handle) {

[siva, 2015/06/19 23:30:46]

Why is it not Ok to allocate the StackZone here instead of passing in a handle
pointer, We are calling Dart_Invoke and it could potentially also create
handles.

[koda, 2015/06/22 17:18:51]

That would make the return value a dangling pointer.

It's true that Dart_Invoke does allocate handles, and it turns out my assertion
did not catch this. The issue is really that the ApiNativeScope should *only* be
around the deserialization (since everything else might allocate handles).

I've updated the CL substantially by:

1. splitting this helper method to allow smaller ApiNativeScopes in the test.
2. adding an ASSERT in handle allocation

PTAL

   Dart_Handle result;
   result = Dart_Invoke(lib, NewString(dart_function), 0, NULL);
   EXPECT_VALID(result);
@@ -1596,8 +1604,8 @@ static Dart_CObject* GetDeserializedDartMessage(Dart_Handle lib,
   // Serialize the list into a message.
   uint8_t* buffer;
   MessageWriter writer(&buffer, &zone_allocator, false);
-  const Object& list = Object::Handle(Api::UnwrapHandle(result));
-  writer.WriteMessage(list);
+  *tmp_handle = Api::UnwrapHandle(result);
+  writer.WriteMessage(*tmp_handle);
   intptr_t buffer_len = writer.BytesWritten();
 
   // Read object back from the snapshot into a C structure.
@@ -1827,10 +1835,12 @@ UNIT_TEST_CASE(DartGeneratedListMessages) {
 
   {
     DARTSCOPE(isolate);
+    StackZone zone(isolate);
+    Object& tmp = Object::Handle();
     {
       // Generate a list of nulls from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getList");
+      Dart_CObject* root = GetDeserializedDartMessage(lib, "getList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -1842,7 +1852,7 @@ UNIT_TEST_CASE(DartGeneratedListMessages) {
     {
       // Generate a list of ints from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getIntList");
+      Dart_CObject* root = GetDeserializedDartMessage(lib, "getIntList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -1855,7 +1865,8 @@ UNIT_TEST_CASE(DartGeneratedListMessages) {
     {
       // Generate a list of strings from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getStringList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getStringList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -1869,7 +1880,8 @@ UNIT_TEST_CASE(DartGeneratedListMessages) {
     {
       // Generate a list of objects of different types from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getMixedList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getMixedList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -1945,10 +1957,12 @@ UNIT_TEST_CASE(DartGeneratedArrayLiteralMessages) {
 
   {
     DARTSCOPE(isolate);
+    StackZone zone(isolate);
+    Object& tmp = Object::Handle();
     {
       // Generate a list of nulls from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getList");
+      Dart_CObject* root = GetDeserializedDartMessage(lib, "getList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -1960,7 +1974,8 @@ UNIT_TEST_CASE(DartGeneratedArrayLiteralMessages) {
     {
       // Generate a list of ints from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getIntList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getIntList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -1973,7 +1988,8 @@ UNIT_TEST_CASE(DartGeneratedArrayLiteralMessages) {
     {
       // Generate a list of strings from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getStringList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getStringList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -1987,7 +2003,8 @@ UNIT_TEST_CASE(DartGeneratedArrayLiteralMessages) {
     {
       // Generate a list of lists from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getListList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getListList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2005,7 +2022,8 @@ UNIT_TEST_CASE(DartGeneratedArrayLiteralMessages) {
     {
       // Generate a list of objects of different types from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getMixedList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getMixedList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2177,11 +2195,13 @@ UNIT_TEST_CASE(DartGeneratedListMessagesWithBackref) {
 
   {
     DARTSCOPE(isolate);
-
+    StackZone zone(isolate);
+    Object& tmp = Object::Handle();
     {
       // Generate a list of strings from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getStringList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getStringList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2195,7 +2215,8 @@ UNIT_TEST_CASE(DartGeneratedListMessagesWithBackref) {
     {
       // Generate a list of medium ints from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getMintList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getMintList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2209,7 +2230,8 @@ UNIT_TEST_CASE(DartGeneratedListMessagesWithBackref) {
     {
       // Generate a list of bigints from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getBigintList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getBigintList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2225,7 +2247,8 @@ UNIT_TEST_CASE(DartGeneratedListMessagesWithBackref) {
     {
       // Generate a list of doubles from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getDoubleList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getDoubleList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2243,7 +2266,8 @@ UNIT_TEST_CASE(DartGeneratedListMessagesWithBackref) {
     {
       // Generate a list of Uint8Lists from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getTypedDataList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getTypedDataList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2259,7 +2283,7 @@ UNIT_TEST_CASE(DartGeneratedListMessagesWithBackref) {
       // Generate a list of Uint8List views from Dart code.
       ApiNativeScope scope;
       Dart_CObject* root =
-          GetDeserializedDartMessage(lib, "getTypedDataViewList");
+          GetDeserializedDartMessage(lib, "getTypedDataViewList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2276,7 +2300,8 @@ UNIT_TEST_CASE(DartGeneratedListMessagesWithBackref) {
     {
       // Generate a list of objects of different types from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getMixedList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getMixedList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2303,7 +2328,8 @@ UNIT_TEST_CASE(DartGeneratedListMessagesWithBackref) {
     {
       // Generate a list of objects of different types from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getSelfRefList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getSelfRefList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2394,10 +2420,13 @@ UNIT_TEST_CASE(DartGeneratedArrayLiteralMessagesWithBackref) {
 
   {
     DARTSCOPE(isolate);
+    StackZone zone(isolate);
+    Object& tmp = Object::Handle();
     {
       // Generate a list of strings from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getStringList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getStringList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2411,7 +2440,8 @@ UNIT_TEST_CASE(DartGeneratedArrayLiteralMessagesWithBackref) {
     {
       // Generate a list of medium ints from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getMintList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getMintList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2425,7 +2455,8 @@ UNIT_TEST_CASE(DartGeneratedArrayLiteralMessagesWithBackref) {
     {
       // Generate a list of bigints from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getBigintList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getBigintList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2441,7 +2472,8 @@ UNIT_TEST_CASE(DartGeneratedArrayLiteralMessagesWithBackref) {
     {
       // Generate a list of doubles from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getDoubleList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getDoubleList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2460,7 +2492,8 @@ UNIT_TEST_CASE(DartGeneratedArrayLiteralMessagesWithBackref) {
     {
       // Generate a list of Uint8Lists from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getTypedDataList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getTypedDataList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2476,7 +2509,7 @@ UNIT_TEST_CASE(DartGeneratedArrayLiteralMessagesWithBackref) {
       // Generate a list of Uint8List views from Dart code.
       ApiNativeScope scope;
       Dart_CObject* root =
-          GetDeserializedDartMessage(lib, "getTypedDataViewList");
+          GetDeserializedDartMessage(lib, "getTypedDataViewList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2493,7 +2526,8 @@ UNIT_TEST_CASE(DartGeneratedArrayLiteralMessagesWithBackref) {
     {
       // Generate a list of objects of different types from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getMixedList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getMixedList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2520,7 +2554,8 @@ UNIT_TEST_CASE(DartGeneratedArrayLiteralMessagesWithBackref) {
     {
       // Generate a list of objects of different types from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getSelfRefList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getSelfRefList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       EXPECT_EQ(kArrayLength, root->value.as_array.length);
@@ -2626,10 +2661,13 @@ UNIT_TEST_CASE(DartGeneratedListMessagesWithTypedData) {
 
   {
     DARTSCOPE(isolate);
+    StackZone zone(isolate);
+    Object& tmp = Object::Handle();
     {
       // Generate a list of Uint8Lists from Dart code.
       ApiNativeScope scope;
-      Dart_CObject* root = GetDeserializedDartMessage(lib, "getTypedDataList");
+      Dart_CObject* root =
+          GetDeserializedDartMessage(lib, "getTypedDataList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       struct {
@@ -2663,7 +2701,7 @@ UNIT_TEST_CASE(DartGeneratedListMessagesWithTypedData) {
 
       ApiNativeScope scope;
       Dart_CObject* root =
-          GetDeserializedDartMessage(lib, "getTypedDataViewList");
+          GetDeserializedDartMessage(lib, "getTypedDataViewList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       struct {
@@ -2719,7 +2757,7 @@ UNIT_TEST_CASE(DartGeneratedListMessagesWithTypedData) {
       // Generate a list of Uint8Lists from Dart code.
       ApiNativeScope scope;
       Dart_CObject* root =
-          GetDeserializedDartMessage(lib, "getMultipleTypedDataViewList");
+          GetDeserializedDartMessage(lib, "getMultipleTypedDataViewList", &tmp);
       EXPECT_NOTNULL(root);
       EXPECT_EQ(Dart_CObject_kArray, root->type);
       struct {