Allocate a Dart_CMessage structure when decoding a message into C structures

runtime/vm/snapshot.cc

Index: runtime/vm/snapshot.cc
diff --git a/runtime/vm/snapshot.cc b/runtime/vm/snapshot.cc
index 2278e4c2fe5928ab88dcdd957633ec7f34eff35a..d0317a1b3f0c862487559174bf2129029e38f9ec 100644
--- a/runtime/vm/snapshot.cc
+++ b/runtime/vm/snapshot.cc
@@ -437,12 +437,22 @@ RawObject* SnapshotReader::ReadInlinedObject(intptr_t object_id) {
 }
 
 
+static uint8_t* allocator(uint8_t* ptr, intptr_t old_size, intptr_t new_size) {
+  return reinterpret_cast<uint8_t*>(realloc(ptr, new_size));
+}
+
+
 CMessageReader::CMessageReader(const uint8_t* buffer,
                                intptr_t length,
                                ReAlloc alloc)
     : BaseReader(buffer, length),
       alloc_(alloc),
-      backward_references_(kNumInitialReferences) {
+      backward_references_(kNumInitialReferences),
+      allocated_(kNumInitialReferences * 2),
+      original_message_(buffer),
+      original_message_length_(length) {
+  // Use default allocator if none specified.
+  if (alloc_ == NULL) alloc_ = allocator;
   // Initialize marker objects used to handle Lists.
   // TODO(sjesse): Remove this when message serialization format is
   // updated.
@@ -455,6 +465,26 @@ CMessageReader::CMessageReader(const uint8_t* buffer,
 }
 
 
+Dart_CMessage* CMessageReader::ReadMessage() {
+  // Read the object out of the message.
+  Dart_CObject* object = ReadObject();
+
+  intptr_t size =
+      sizeof(Dart_CMessage) + allocated_.length() * sizeof(Dart_CObject*);  // NOLINT
+  Dart_CMessage* message =
+      reinterpret_cast<Dart_CMessage*>(alloc_(NULL, 0, size));
+  message->allocated = reinterpret_cast<Dart_CObject**>(message + 1);
+  if (message == NULL) return NULL;

[siva, 2012/02/01 01:48:36]

The null check for message should happen before message is accessed in the line
above?

[Søren Gjesse, 2012/02/01 12:12:23]

Done.

+  message->object = object;
+  message->allocated_length = allocated_.length();
+  for (int i = 0; i < allocated_.length(); i++) {
+    message->allocated[i] = allocated_[i];
+  }

[siva, 2012/02/01 01:48:36]

Not sure if we need to do this copying over here. Please see comment in
dart_api.h

[Søren Gjesse, 2012/02/01 12:12:23]

Only needed if pointing back into the message and embedder is responsible for
freeing. Removed.

+  message->original_message = const_cast<uint8_t*>(original_message_);
+  message->original_message_length = original_message_length_;
+  return message;
+}
+
 intptr_t CMessageReader::LookupInternalClass(intptr_t class_header) {
   SerializedHeaderType header_type = SerializedHeaderTag::decode(class_header);
   ASSERT(header_type == kObjectId);
@@ -467,6 +497,7 @@ Dart_CObject* CMessageReader::AllocateDartCObject(Dart_CObject::Type type) {
   Dart_CObject* value =
       reinterpret_cast<Dart_CObject*>(
           alloc_(NULL, 0, sizeof(Dart_CObject)));
+  allocated_.Add(value);
   value->type = type;
   return value;
 }
@@ -505,6 +536,7 @@ Dart_CObject* CMessageReader::AllocateDartCObjectString(intptr_t length) {
   Dart_CObject* value =
       reinterpret_cast<Dart_CObject*>(
           alloc_(NULL, 0, sizeof(Dart_CObject) + length + 1));
+  allocated_.Add(value);
   value->value.as_string = reinterpret_cast<char*>(value) + sizeof(*value);
   value->type = Dart_CObject::kString;
   return value;
@@ -518,6 +550,7 @@ Dart_CObject* CMessageReader::AllocateDartCObjectArray(intptr_t length) {
   Dart_CObject* value =
       reinterpret_cast<Dart_CObject*>(
           alloc_(NULL, 0, sizeof(Dart_CObject) + length * sizeof(value)));
+  allocated_.Add(value);
   value->type = Dart_CObject::kArray;
   value->value.as_array.length = length;
   if (length > 0) {