1// Copyright 2017 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#include "src/snapshot/context-deserializer.h"
6
7#include "src/api/api-inl.h"
8#include "src/common/assert-scope.h"
9#include "src/heap/heap-inl.h"
10#include "src/objects/js-array-buffer-inl.h"
11#include "src/objects/slots.h"
12#include "src/snapshot/snapshot.h"
13
14namespace v8 {
15namespace internal {
16
17MaybeHandle<Context> ContextDeserializer::DeserializeContext(
18    Isolate* isolate, const SnapshotData* data, bool can_rehash,
19    Handle<JSGlobalProxy> global_proxy,
20    v8::DeserializeEmbedderFieldsCallback embedder_fields_deserializer) {
21  ContextDeserializer d(isolate, data, can_rehash);
22
23  MaybeHandle<Object> maybe_result =
24      d.Deserialize(isolate, global_proxy, embedder_fields_deserializer);
25
26  Handle<Object> result;
27  return maybe_result.ToHandle(&result) ? Handle<Context>::cast(result)
28                                        : MaybeHandle<Context>();
29}
30
31MaybeHandle<Object> ContextDeserializer::Deserialize(
32    Isolate* isolate, Handle<JSGlobalProxy> global_proxy,
33    v8::DeserializeEmbedderFieldsCallback embedder_fields_deserializer) {
34  // Replace serialized references to the global proxy and its map with the
35  // given global proxy and its map.
36  AddAttachedObject(global_proxy);
37  AddAttachedObject(handle(global_proxy->map(), isolate));
38
39  Handle<Object> result;
40  {
41    // There's no code deserialized here. If this assert fires then that's
42    // changed and logging should be added to notify the profiler et al. of
43    // the new code, which also has to be flushed from instruction cache.
44    DisallowCodeAllocation no_code_allocation;
45
46    result = ReadObject();
47    DeserializeDeferredObjects();
48    DeserializeEmbedderFields(embedder_fields_deserializer);
49
50    LogNewMapEvents();
51    WeakenDescriptorArrays();
52  }
53
54  if (should_rehash()) Rehash();
55  SetupOffHeapArrayBufferBackingStores();
56
57  return result;
58}
59
60void ContextDeserializer::SetupOffHeapArrayBufferBackingStores() {
61  for (Handle<JSArrayBuffer> buffer : new_off_heap_array_buffers()) {
62    uint32_t store_index = buffer->GetBackingStoreRefForDeserialization();
63    auto bs = backing_store(store_index);
64    SharedFlag shared =
65        bs && bs->is_shared() ? SharedFlag::kShared : SharedFlag::kNotShared;
66    DCHECK_IMPLIES(bs, buffer->is_resizable() == bs->is_resizable());
67    ResizableFlag resizable = bs && bs->is_resizable()
68                                  ? ResizableFlag::kResizable
69                                  : ResizableFlag::kNotResizable;
70    buffer->Setup(shared, resizable, bs);
71  }
72}
73
74void ContextDeserializer::DeserializeEmbedderFields(
75    v8::DeserializeEmbedderFieldsCallback embedder_fields_deserializer) {
76  if (!source()->HasMore() || source()->Get() != kEmbedderFieldsData) return;
77  DisallowGarbageCollection no_gc;
78  DisallowJavascriptExecution no_js(isolate());
79  DisallowCompilation no_compile(isolate());
80  DCHECK_NOT_NULL(embedder_fields_deserializer.callback);
81  for (int code = source()->Get(); code != kSynchronize;
82       code = source()->Get()) {
83    HandleScope scope(isolate());
84    Handle<JSObject> obj = Handle<JSObject>::cast(GetBackReferencedObject());
85    int index = source()->GetInt();
86    int size = source()->GetInt();
87    // TODO(yangguo,jgruber): Turn this into a reusable shared buffer.
88    byte* data = new byte[size];
89    source()->CopyRaw(data, size);
90    embedder_fields_deserializer.callback(v8::Utils::ToLocal(obj), index,
91                                          {reinterpret_cast<char*>(data), size},
92                                          embedder_fields_deserializer.data);
93    delete[] data;
94  }
95}
96}  // namespace internal
97}  // namespace v8
98