Avoid trusting the length encoded in the Snapshot if there is an

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
===================================================================
--- runtime/vm/dart_api_impl.cc	(revision 10993)
+++ runtime/vm/dart_api_impl.cc	(working copy)
@@ -823,8 +823,7 @@
   // Since this is only a snapshot the root library should not be set.
   isolate->object_store()->set_root_library(Library::Handle(isolate));
   SnapshotWriter writer(Snapshot::kFull, buffer, ApiReallocate);
-  writer.WriteFullSnapshot();
-  *size = writer.BytesWritten();
+  *size = writer.WriteFullSnapshot();

[siva, 2012/08/22 23:30:39]

I would prefer not returning the size as a return value from WriteFullSnapshot
because we may want to return an error once we beef it up for chunked writing.

[turnidge, 2012/08/23 18:37:57]

Done.

   return Api::Success(isolate);
 }
 
@@ -852,8 +851,7 @@
                       CURRENT_FUNC);
   }
   ScriptSnapshotWriter writer(buffer, ApiReallocate);
-  writer.WriteScriptSnapshot(library);
-  *size = writer.BytesWritten();
+  *size = writer.WriteScriptSnapshot(library);
   return Api::Success(isolate);
 }
 
@@ -954,11 +952,12 @@
   uint8_t* buffer = NULL;
   ApiMessageWriter writer(&buffer, &allocator);
 
-  writer.WriteMessage(len, data);
+  intptr_t buffer_len = writer.WriteMessage(len, data);
 
   // Post the message at the given port.
   return PortMap::PostMessage(new Message(
-      port_id, Message::kIllegalPort, buffer, Message::kNormalPriority));
+      port_id, Message::kIllegalPort, buffer, buffer_len,
+      Message::kNormalPriority));
 }
 
 
@@ -966,11 +965,12 @@
   uint8_t* buffer = NULL;
   ApiMessageWriter writer(&buffer, allocator);
 
-  writer.WriteCMessage(message);
+  intptr_t buffer_len = writer.WriteCMessage(message);
 
   // Post the message at the given port.
   return PortMap::PostMessage(new Message(
-      port_id, Message::kIllegalPort, buffer, Message::kNormalPriority));
+      port_id, Message::kIllegalPort, buffer, buffer_len,
+      Message::kNormalPriority));
 }
 
 
@@ -982,9 +982,9 @@
   uint8_t* data = NULL;
   SnapshotWriter writer(Snapshot::kMessage, &data, &allocator);
   writer.WriteObject(object.raw());
-  writer.FinalizeBuffer();
+  intptr_t len = writer.FinalizeBuffer();
   return PortMap::PostMessage(new Message(
-      port_id, Message::kIllegalPort, data, Message::kNormalPriority));
+      port_id, Message::kIllegalPort, data, len, Message::kNormalPriority));
 }
 
 
@@ -3783,10 +3783,15 @@
   if (buffer == NULL) {
     RETURN_NULL_ERROR(buffer);
   }
-  const Snapshot* snapshot = Snapshot::SetupFromBuffer(buffer);
+  const Snapshot* snapshot =
+      Snapshot::SetupFromBuffer(buffer, Snapshot::kTrustedLength);
+  if (snapshot == NULL) {
+    return Api::NewError("%s: unexpected error during snapshot parsing."
+                         " snapshot", CURRENT_FUNC);
+  }
   if (!snapshot->IsScriptSnapshot()) {
     return Api::NewError("%s expects parameter 'buffer' to be a script type"
-                         " snapshot", CURRENT_FUNC);
+                         " snapshot.", CURRENT_FUNC);
   }
   Library& library =
       Library::Handle(isolate, isolate->object_store()->root_library());