snapshot-data.cc

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// Copyright 2020 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/snapshot/snapshot-data.h"
 
#include "src/common/assert-scope.h"
#include "src/snapshot/serializer.h"
 
namespace v8 {
namespace internal {
 
void SerializedData::AllocateData(uint32_t size) {
  DCHECK(!owns_data_);
  data_ = NewArray<uint8_t>(size);
  size_ = size;
  owns_data_ = true;
}
 
// static
constexpr uint32_t SerializedData::kMagicNumber;
 
SnapshotData::SnapshotData(const Serializer* serializer) {
  DisallowGarbageCollection no_gc;
  const std::vector<uint8_t>* payload = serializer->Payload();
 
  // Calculate sizes.
  uint32_t size = kHeaderSize + static_cast<uint32_t>(payload->size());
 
  // Allocate backing store and create result data.
  AllocateData(size);
 
  // Zero out pre-payload data. Part of that is only used for padding.
  memset(data_, 0, kHeaderSize);
 
  // Set header values.
  SetMagicNumber();
  SetHeaderValue(kPayloadLengthOffset, static_cast<int>(payload->size()));
 
  // Copy serialized data.
  CopyBytes(data_ + kHeaderSize, payload->data(),
            static_cast<size_t>(payload->size()));
}
 
base::Vector<const uint8_t> SnapshotData::Payload() const {
  const uint8_t* payload = data_ + kHeaderSize;
  uint32_t length = GetHeaderValue(kPayloadLengthOffset);
  DCHECK_EQ(data_ + size_, payload + length);
  return base::Vector<const uint8_t>(payload, length);
}
 
}  // namespace internal
}  // namespace v8