Extract non-IO part of mksnapshot into an API method.

src/snapshot-common.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // The common functionality when building with or without snapshots.
 
 #include "src/v8.h"
 
 #include "src/api.h"
 #include "src/base/platform/platform.h"
 #include "src/serialize.h"
 #include "src/snapshot.h"
 
 namespace v8 {
 namespace internal {
 
 bool Snapshot::HaveASnapshotToStartFrom() {
   return SnapshotBlob().data != NULL;
 }
 
 
-const Vector<const byte> Snapshot::StartupSnapshot() {
-  DCHECK(HaveASnapshotToStartFrom());
-  const v8::StartupData blob = SnapshotBlob();
-  SnapshotByteSource source(blob.data, blob.raw_size);
-  const byte* data;
-  int length;
-  bool success = source.GetBlob(&data, &length);
-  CHECK(success);
-  return Vector<const byte>(data, length);
-}
-
-
-const Vector<const byte> Snapshot::ContextSnapshot() {
-  DCHECK(HaveASnapshotToStartFrom());
-  const v8::StartupData blob = SnapshotBlob();
-  SnapshotByteSource source(blob.data, blob.raw_size);
-  const byte* data;
-  int length;
-  bool success = source.GetBlob(&data, &length);
-  success &= source.GetBlob(&data, &length);
-  CHECK(success);
-  return Vector<const byte>(data, length);
-}
-
-
 bool Snapshot::Initialize(Isolate* isolate) {
   if (!HaveASnapshotToStartFrom()) return false;
   base::ElapsedTimer timer;
   if (FLAG_profile_deserialization) timer.Start();
 
-  SnapshotData snapshot_data(StartupSnapshot());
+  const v8::StartupData blob = SnapshotBlob();
+  SnapshotData snapshot_data(ExtractStartupData(&blob));
   Deserializer deserializer(&snapshot_data);
   bool success = isolate->Init(&deserializer);
   if (FLAG_profile_deserialization) {
     double ms = timer.Elapsed().InMillisecondsF();
     PrintF("[Snapshot loading and deserialization took %0.3f ms]\n", ms);
   }
   return success;
 }
 
 
 Handle<Context> Snapshot::NewContextFromSnapshot(Isolate* isolate) {
   if (!HaveASnapshotToStartFrom()) return Handle<Context>();
 
-  SnapshotData snapshot_data(ContextSnapshot());
+  const v8::StartupData blob = SnapshotBlob();
+  SnapshotData snapshot_data(ExtractContextData(&blob));
   Deserializer deserializer(&snapshot_data);
   Object* root;
   deserializer.DeserializePartial(isolate, &root);
   CHECK(root->IsContext());
   return Handle<Context>(Context::cast(root));
 }
 
+
+v8::StartupData Snapshot::CreateSnapshotBlob(
+    const Vector<const byte> startup_data,
+    const Vector<const byte> context_data) {
+  int startup_length = startup_data.length();
+  int context_length = context_data.length();
+  int context_offset = kIntSize + startup_length;
+  int length = context_offset + context_length;
+  char* data = new char[length];
+
+  memcpy(data, &startup_length, kIntSize);
+  memcpy(data + kIntSize, startup_data.begin(), startup_length);
+  memcpy(data + context_offset, context_data.begin(), context_length);
+  v8::StartupData result = {data, length};
+  return result;
+}
+
+
+Vector<const byte> Snapshot::ExtractStartupData(const v8::StartupData* data) {
+  DCHECK_LT(kIntSize, data->raw_size);
+  int startup_length;
+  memcpy(&startup_length, data->data, kIntSize);
+  DCHECK_LT(startup_length, data->raw_size);
+  const byte* startup_data =
+      reinterpret_cast<const byte*>(data->data + kIntSize);
+  return Vector<const byte>(startup_data, startup_length);
+}
+
+
+Vector<const byte> Snapshot::ExtractContextData(const v8::StartupData* data) {
+  DCHECK_LT(kIntSize, data->raw_size);
+  int startup_length;
+  memcpy(&startup_length, data->data, kIntSize);
+  int context_offset = kIntSize + startup_length;
+  const byte* context_data =
+      reinterpret_cast<const byte*>(data->data + context_offset);
+  DCHECK_LT(context_offset, data->raw_size);
+  int context_length = data->raw_size - context_offset;
+  return Vector<const byte>(context_data, context_length);
+}
 } }  // namespace v8::internal