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

runtime/vm/dart_api_impl.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "include/dart_api.h"
 
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/compiler.h"
 #include "vm/dart.h"
@@ skipping 797 matching lines @@
   }
   if (size == NULL) {
     RETURN_NULL_ERROR(size);
   }
   const char* msg = CheckIsolateState(isolate);
   if (msg != NULL) {
     return Api::NewError(msg);
   }
   // 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);
+  FullSnapshotWriter writer(buffer, ApiReallocate);
   writer.WriteFullSnapshot();
   *size = writer.BytesWritten();
   return Api::Success(isolate);
 }
 
 
 DART_EXPORT Dart_Handle Dart_CreateScriptSnapshot(uint8_t** buffer,
                                                   intptr_t* size) {
   Isolate* isolate = Isolate::Current();
   DARTSCOPE(isolate);
@@ skipping 110 matching lines @@
   void* new_ptr = realloc(reinterpret_cast<void*>(ptr), new_size);
   return reinterpret_cast<uint8_t*>(new_ptr);
 }
 
 
 DART_EXPORT bool Dart_PostIntArray(Dart_Port port_id,
                                    intptr_t len,
                                    intptr_t* data) {
   uint8_t* buffer = NULL;
   ApiMessageWriter writer(&buffer, &allocator);
-
   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, writer.BytesWritten(),
+      Message::kNormalPriority));
 }
 
 
 DART_EXPORT bool Dart_PostCObject(Dart_Port port_id, Dart_CObject* message) {
   uint8_t* buffer = NULL;
   ApiMessageWriter writer(&buffer, allocator);
-
   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, writer.BytesWritten(),
+      Message::kNormalPriority));
 }
 
 
 DART_EXPORT bool Dart_Post(Dart_Port port_id, Dart_Handle handle) {
   Isolate* isolate = Isolate::Current();
   CHECK_ISOLATE(isolate);
   DARTSCOPE_NOCHECKS(isolate);
   const Object& object = Object::Handle(isolate, Api::UnwrapHandle(handle));
   uint8_t* data = NULL;
-  SnapshotWriter writer(Snapshot::kMessage, &data, &allocator);
-  writer.WriteObject(object.raw());
-  writer.FinalizeBuffer();
+  MessageWriter writer(&data, &allocator);
+  writer.WriteMessage(object);
+  intptr_t len = writer.BytesWritten();
   return PortMap::PostMessage(new Message(
-      port_id, Message::kIllegalPort, data, Message::kNormalPriority));
+      port_id, Message::kIllegalPort, data, len, Message::kNormalPriority));
 }
 
 
 DART_EXPORT Dart_Port Dart_NewNativePort(const char* name,
                                          Dart_NativeMessageHandler handler,
                                          bool handle_concurrently) {
   if (name == NULL) {
     name = "<UnnamedNativePort>";
   }
   if (handler == NULL) {
@@ skipping 2829 matching lines @@
   TIMERSCOPE(time_script_loading);
   if (buffer == NULL) {
     RETURN_NULL_ERROR(buffer);
   }
   if (FLAG_use_cha) {
     RemoveOptimizedCode();
   }
   const Snapshot* snapshot = Snapshot::SetupFromBuffer(buffer);
   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());
   if (!library.IsNull()) {
     const String& library_url = String::Handle(isolate, library.url());
     return Api::NewError("%s: A script has already been loaded from '%s'.",
                          CURRENT_FUNC, library_url.ToCString());
   }
-  SnapshotReader reader(snapshot, isolate);
+  SnapshotReader reader(snapshot->content(),
+                        snapshot->length(),
+                        snapshot->kind(),
+                        isolate);
   const Object& tmp = Object::Handle(isolate, reader.ReadObject());
   if (!tmp.IsLibrary()) {
     return Api::NewError("%s: Unable to deserialize snapshot correctly.",
                          CURRENT_FUNC);
   }
   library ^= tmp.raw();
   library.set_debuggable(true);
   isolate->object_store()->set_root_library(library);
   return Api::NewHandle(isolate, library.raw());
 }
@@ skipping 278 matching lines @@
 DART_EXPORT void Dart_InitPerfEventsSupport(Dart_FileWriterFunction function) {
   Dart::set_perf_events_writer(function);
 }
 
 
 DART_EXPORT void Dart_InitFlowGraphPrinting(Dart_FileWriterFunction function) {
   Dart::set_flow_graph_writer(function);
 }
 
 }  // namespace dart