Blink-compatible serialization of oddball values.

BUG=chromium:148757

Review-Url: https://codereview.chromium.org/2232243003
Cr-Commit-Position: refs/heads/master@{#38625}

BUILD.gn

@@ -1625,6 +1625,8 @@ v8_source_set("v8_base") {
     "src/v8memory.h",
     "src/v8threads.cc",
     "src/v8threads.h",
+    "src/value-serializer.cc",
+    "src/value-serializer.h",
     "src/version.cc",
     "src/version.h",
     "src/vm-state-inl.h",

src/v8.gyp

@@ -1231,6 +1231,8 @@
         'v8memory.h',
         'v8threads.cc',
         'v8threads.h',
+        'value-serializer.cc',
+        'value-serializer.h',
         'vector.h',
         'version.cc',
         'version.h',

src/value-serializer.cc

@@ -0,0 +1,174 @@
+// Copyright 2016 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.
+
+#include "src/value-serializer.h"
+
+#include <type_traits>
+
+#include "src/base/logging.h"
+#include "src/factory.h"
+#include "src/handles-inl.h"
+#include "src/isolate.h"
+#include "src/objects-inl.h"
+#include "src/objects.h"
+
+namespace v8 {
+namespace internal {
+
+static const uint32_t kLatestVersion = 9;
+
+enum class SerializationTag : uint8_t {
+  kVersion = 0xFF,
+  kPadding = '\0',
+  kVerifyObjectCount = '?',
+  kUndefined = '_',
+  kNull = '0',
+  kTrue = 'T',
+  kFalse = 'F',
+};
+
+ValueSerializer::ValueSerializer() {}
+
+ValueSerializer::~ValueSerializer() {}
+
+void ValueSerializer::WriteHeader() {
+  WriteTag(SerializationTag::kVersion);
+  WriteVarint(kLatestVersion);
+}
+
+void ValueSerializer::WriteTag(SerializationTag tag) {
+  buffer_.push_back(static_cast<uint8_t>(tag));
+}
+
+template <typename T>
+void ValueSerializer::WriteVarint(T value) {
+  // Writes an unsigned integer as a base-128 varint.
+  // The number is written, 7 bits at a time, from the least significant to the
+  // most significant 7 bits. Each byte, except the last, has the MSB set.
+  // See also https://developers.google.com/protocol-buffers/docs/encoding
+  static_assert(std::is_integral<T>::value && std::is_unsigned<T>::value,
+                "Only unsigned integer types can be written as varints.");
+  uint8_t stack_buffer[sizeof(T) * 8 / 7 + 1];
+  uint8_t* next_byte = &stack_buffer[0];
+  do {
+    *next_byte = (value & 0x7f) | 0x80;
+    next_byte++;
+    value >>= 7;
+  } while (value);
+  *(next_byte - 1) &= 0x7f;
+  buffer_.insert(buffer_.end(), stack_buffer, next_byte);
+}
+
+Maybe<bool> ValueSerializer::WriteObject(Handle<Object> object) {
+  if (object->IsSmi()) UNIMPLEMENTED();
+
+  DCHECK(object->IsHeapObject());
+  switch (HeapObject::cast(*object)->map()->instance_type()) {
+    case ODDBALL_TYPE:
+      WriteOddball(Oddball::cast(*object));
+      return Just(true);
+    default:
+      UNIMPLEMENTED();
+      return Nothing<bool>();
+  }
+}
+
+void ValueSerializer::WriteOddball(Oddball* oddball) {
+  SerializationTag tag = SerializationTag::kUndefined;
+  switch (oddball->kind()) {
+    case Oddball::kUndefined:
+      tag = SerializationTag::kUndefined;
+      break;
+    case Oddball::kFalse:
+      tag = SerializationTag::kFalse;
+      break;
+    case Oddball::kTrue:
+      tag = SerializationTag::kTrue;
+      break;
+    case Oddball::kNull:
+      tag = SerializationTag::kNull;
+      break;
+    default:
+      UNREACHABLE();
+      break;
+  }
+  WriteTag(tag);
+}
+
+ValueDeserializer::ValueDeserializer(Isolate* isolate,
+                                     Vector<const uint8_t> data)
+    : isolate_(isolate),
+      position_(data.start()),
+      end_(data.start() + data.length()) {}
+
+ValueDeserializer::~ValueDeserializer() {}
+
+Maybe<bool> ValueDeserializer::ReadHeader() {
+  if (position_ < end_ &&
+      *position_ == static_cast<uint8_t>(SerializationTag::kVersion)) {
+    ReadTag().ToChecked();
+    if (!ReadVarint<uint32_t>().To(&version_)) return Nothing<bool>();
+    if (version_ > kLatestVersion) return Nothing<bool>();
+  }
+  return Just(true);
+}
+
+Maybe<SerializationTag> ValueDeserializer::ReadTag() {
+  SerializationTag tag;
+  do {
+    if (position_ >= end_) return Nothing<SerializationTag>();
+    tag = static_cast<SerializationTag>(*position_);
+    position_++;
+  } while (tag == SerializationTag::kPadding);
+  return Just(tag);
+}
+
+template <typename T>
+Maybe<T> ValueDeserializer::ReadVarint() {
+  // Reads an unsigned integer as a base-128 varint.
+  // The number is written, 7 bits at a time, from the least significant to the
+  // most significant 7 bits. Each byte, except the last, has the MSB set.
+  // If the varint is larger than T, any more significant bits are discarded.
+  // See also https://developers.google.com/protocol-buffers/docs/encoding
+  static_assert(std::is_integral<T>::value && std::is_unsigned<T>::value,
+                "Only unsigned integer types can be read as varints.");
+  T value = 0;
+  unsigned shift = 0;
+  bool has_another_byte;
+  do {
+    if (position_ >= end_) return Nothing<T>();
+    uint8_t byte = *position_;
+    if (V8_LIKELY(shift < sizeof(T) * 8)) {
+      value |= (byte & 0x7f) << shift;
+      shift += 7;
+    }
+    has_another_byte = byte & 0x80;
+    position_++;
+  } while (has_another_byte);
+  return Just(value);
+}
+
+MaybeHandle<Object> ValueDeserializer::ReadObject() {
+  SerializationTag tag;
+  if (!ReadTag().To(&tag)) return MaybeHandle<Object>();
+  switch (tag) {
+    case SerializationTag::kVerifyObjectCount:
+      // Read the count and ignore it.
+      if (ReadVarint<uint32_t>().IsNothing()) return MaybeHandle<Object>();
+      return ReadObject();
+    case SerializationTag::kUndefined:
+      return isolate_->factory()->undefined_value();
+    case SerializationTag::kNull:
+      return isolate_->factory()->null_value();
+    case SerializationTag::kTrue:
+      return isolate_->factory()->true_value();
+    case SerializationTag::kFalse:
+      return isolate_->factory()->false_value();
+    default:
+      return MaybeHandle<Object>();
+  }
+}
+
+}  // namespace internal
+}  // namespace v8

src/value-serializer.h

@@ -0,0 +1,101 @@
+// Copyright 2016 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.
+
+#ifndef V8_VALUE_SERIALIZER_H_
+#define V8_VALUE_SERIALIZER_H_
+
+#include <cstdint>
+#include <vector>
+
+#include "include/v8.h"
+#include "src/base/compiler-specific.h"
+#include "src/base/macros.h"
+#include "src/vector.h"
+
+namespace v8 {
+namespace internal {
+
+class Isolate;
+class Object;
+class Oddball;
+
+enum class SerializationTag : uint8_t;
+
+/**
+ * Writes V8 objects in a binary format that allows the objects to be cloned
+ * according to the HTML structured clone algorithm.
+ *
+ * Format is based on Blink's previous serialization logic.
+ */
+class ValueSerializer {
+ public:
+  ValueSerializer();
+  ~ValueSerializer();
+
+  /*
+   * Writes out a header, which includes the format version.
+   */
+  void WriteHeader();
+
+  /*
+   * Serializes a V8 object into the buffer.
+   */
+  Maybe<bool> WriteObject(Handle<Object> object) WARN_UNUSED_RESULT;
+
+  /*
+   * Returns the stored data. This serializer should not be used once the buffer
+   * is released. The contents are undefined if a previous write has failed.
+   */
+  std::vector<uint8_t> ReleaseBuffer() { return std::move(buffer_); }
+
+ private:
+  // Writing the wire format.
+  void WriteTag(SerializationTag tag);
+  template <typename T>
+  void WriteVarint(T value);
+
+  // Writing V8 objects of various kinds.
+  void WriteOddball(Oddball* oddball);
+
+  std::vector<uint8_t> buffer_;
+
+  DISALLOW_COPY_AND_ASSIGN(ValueSerializer);
+};
+
+/*
+ * Deserializes values from data written with ValueSerializer, or a compatible
+ * implementation.
+ */
+class ValueDeserializer {
+ public:
+  ValueDeserializer(Isolate* isolate, Vector<const uint8_t> data);
+  ~ValueDeserializer();
+
+  /*
+   * Runs version detection logic, which may fail if the format is invalid.
+   */
+  Maybe<bool> ReadHeader() WARN_UNUSED_RESULT;
+
+  /*
+   * Deserializes a V8 object from the buffer.
+   */
+  MaybeHandle<Object> ReadObject() WARN_UNUSED_RESULT;
+
+ private:
+  Maybe<SerializationTag> ReadTag() WARN_UNUSED_RESULT;
+  template <typename T>
+  Maybe<T> ReadVarint() WARN_UNUSED_RESULT;
+
+  Isolate* const isolate_;
+  const uint8_t* position_;
+  const uint8_t* const end_;
+  uint32_t version_ = 0;
+
+  DISALLOW_COPY_AND_ASSIGN(ValueDeserializer);
+};
+
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_VALUE_SERIALIZER_H_

test/unittests/unittests.gyp

@@ -112,6 +112,7 @@
       'source-position-table-unittest.cc',
       'test-utils.h',
       'test-utils.cc',
+      'value-serializer-unittest.cc',
       'wasm/asm-types-unittest.cc',
       'wasm/ast-decoder-unittest.cc',
       'wasm/control-transfer-unittest.cc',

test/unittests/value-serializer-unittest.cc

@@ -0,0 +1,167 @@
+// Copyright 2016 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.
+
+#include "src/value-serializer.h"
+#include "include/v8.h"
+#include "src/api.h"
+#include "test/unittests/test-utils.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace v8 {
+namespace {
+
+class ValueSerializerTest : public TestWithIsolate {
+ protected:
+  ValueSerializerTest()
+      : serialization_context_(Context::New(isolate())),
+        deserialization_context_(Context::New(isolate())) {}
+
+  const Local<Context>& serialization_context() {
+    return serialization_context_;
+  }
+  const Local<Context>& deserialization_context() {
+    return deserialization_context_;
+  }
+
+  template <typename InputFunctor, typename OutputFunctor>
+  void RoundTripTest(const InputFunctor& input_functor,
+                     const OutputFunctor& output_functor) {
+    std::vector<uint8_t> data;
+    {
+      Context::Scope scope(serialization_context());
+      TryCatch try_catch(isolate());
+      // TODO(jbroman): Use the public API once it exists.
+      Local<Value> input_value = input_functor();
+      i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate());
+      i::HandleScope handle_scope(internal_isolate);
+      i::ValueSerializer serializer;
+      serializer.WriteHeader();
+      ASSERT_TRUE(serializer.WriteObject(Utils::OpenHandle(*input_value))
+                      .FromMaybe(false));
+      ASSERT_FALSE(try_catch.HasCaught());
+      data = serializer.ReleaseBuffer();
+    }
+    DecodeTest(data, output_functor);
+  }
+
+  template <typename OutputFunctor>
+  void DecodeTest(const std::vector<uint8_t>& data,
+                  const OutputFunctor& output_functor) {
+    Context::Scope scope(deserialization_context());
+    TryCatch try_catch(isolate());
+    // TODO(jbroman): Use the public API once it exists.
+    i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate());
+    i::HandleScope handle_scope(internal_isolate);
+    i::ValueDeserializer deserializer(
+        internal_isolate,
+        i::Vector<const uint8_t>(&data[0], static_cast<int>(data.size())));
+    ASSERT_TRUE(deserializer.ReadHeader().FromMaybe(false));
+    Local<Value> result;
+    ASSERT_TRUE(ToLocal<Value>(deserializer.ReadObject(), &result));
+    ASSERT_FALSE(result.IsEmpty());
+    ASSERT_FALSE(try_catch.HasCaught());
+    ASSERT_TRUE(deserialization_context()
+                    ->Global()
+                    ->CreateDataProperty(deserialization_context_,
+                                         StringFromUtf8("result"), result)
+                    .FromMaybe(false));
+    output_functor(result);
+    ASSERT_FALSE(try_catch.HasCaught());
+  }
+
+  void InvalidDecodeTest(const std::vector<uint8_t>& data) {
+    Context::Scope scope(deserialization_context());
+    TryCatch try_catch(isolate());
+    i::Isolate* internal_isolate = reinterpret_cast<i::Isolate*>(isolate());
+    i::HandleScope handle_scope(internal_isolate);
+    i::ValueDeserializer deserializer(
+        internal_isolate,
+        i::Vector<const uint8_t>(&data[0], static_cast<int>(data.size())));
+    Maybe<bool> header_result = deserializer.ReadHeader();
+    if (header_result.IsNothing()) return;
+    ASSERT_TRUE(header_result.ToChecked());
+    ASSERT_TRUE(deserializer.ReadObject().is_null());
+  }
+
+  Local<Value> EvaluateScriptForInput(const char* utf8_source) {
+    Local<String> source = StringFromUtf8(utf8_source);
+    Local<Script> script =
+        Script::Compile(serialization_context_, source).ToLocalChecked();
+    return script->Run(serialization_context_).ToLocalChecked();
+  }
+
+  bool EvaluateScriptForResultBool(const char* utf8_source) {
+    Local<String> source = StringFromUtf8(utf8_source);
+    Local<Script> script =
+        Script::Compile(deserialization_context_, source).ToLocalChecked();
+    Local<Value> value = script->Run(deserialization_context_).ToLocalChecked();
+    return value->BooleanValue(deserialization_context_).FromJust();
+  }
+
+  Local<String> StringFromUtf8(const char* source) {
+    return String::NewFromUtf8(isolate(), source, NewStringType::kNormal)
+        .ToLocalChecked();
+  }
+
+ private:
+  Local<Context> serialization_context_;
+  Local<Context> deserialization_context_;
+
+  DISALLOW_COPY_AND_ASSIGN(ValueSerializerTest);
+};
+
+TEST_F(ValueSerializerTest, DecodeInvalid) {
+  // Version tag but no content.
+  InvalidDecodeTest({0xff});
+  // Version too large.
+  InvalidDecodeTest({0xff, 0x7f, 0x5f});
+  // Nonsense tag.
+  InvalidDecodeTest({0xff, 0x09, 0xdd});
+}
+
+TEST_F(ValueSerializerTest, RoundTripOddball) {
+  RoundTripTest([this]() { return Undefined(isolate()); },
+                [](Local<Value> value) { EXPECT_TRUE(value->IsUndefined()); });
+  RoundTripTest([this]() { return True(isolate()); },
+                [](Local<Value> value) { EXPECT_TRUE(value->IsTrue()); });
+  RoundTripTest([this]() { return False(isolate()); },
+                [](Local<Value> value) { EXPECT_TRUE(value->IsFalse()); });
+  RoundTripTest([this]() { return Null(isolate()); },
+                [](Local<Value> value) { EXPECT_TRUE(value->IsNull()); });
+}
+
+TEST_F(ValueSerializerTest, DecodeOddball) {
+  // What this code is expected to generate.
+  DecodeTest({0xff, 0x09, 0x5f},
+             [](Local<Value> value) { EXPECT_TRUE(value->IsUndefined()); });
+  DecodeTest({0xff, 0x09, 0x54},
+             [](Local<Value> value) { EXPECT_TRUE(value->IsTrue()); });
+  DecodeTest({0xff, 0x09, 0x46},
+             [](Local<Value> value) { EXPECT_TRUE(value->IsFalse()); });
+  DecodeTest({0xff, 0x09, 0x30},
+             [](Local<Value> value) { EXPECT_TRUE(value->IsNull()); });
+
+  // What v9 of the Blink code generates.
+  DecodeTest({0xff, 0x09, 0x3f, 0x00, 0x5f, 0x00},
+             [](Local<Value> value) { EXPECT_TRUE(value->IsUndefined()); });
+  DecodeTest({0xff, 0x09, 0x3f, 0x00, 0x54, 0x00},
+             [](Local<Value> value) { EXPECT_TRUE(value->IsTrue()); });
+  DecodeTest({0xff, 0x09, 0x3f, 0x00, 0x46, 0x00},
+             [](Local<Value> value) { EXPECT_TRUE(value->IsFalse()); });
+  DecodeTest({0xff, 0x09, 0x3f, 0x00, 0x30, 0x00},
+             [](Local<Value> value) { EXPECT_TRUE(value->IsNull()); });
+
+  // v0 (with no explicit version).
+  DecodeTest({0x5f, 0x00},
+             [](Local<Value> value) { EXPECT_TRUE(value->IsUndefined()); });
+  DecodeTest({0x54, 0x00},
+             [](Local<Value> value) { EXPECT_TRUE(value->IsTrue()); });
+  DecodeTest({0x46, 0x00},
+             [](Local<Value> value) { EXPECT_TRUE(value->IsFalse()); });
+  DecodeTest({0x30, 0x00},
+             [](Local<Value> value) { EXPECT_TRUE(value->IsNull()); });
+}
+
+}  // namespace
+}  // namespace v8