// Copyright 2021 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 INCLUDE_V8_VALUE_SERIALIZER_H_
#define INCLUDE_V8_VALUE_SERIALIZER_H_
#include <stddef.h>
#include <stdint.h>
#include <memory>
#include <utility>
#include "v8-local-handle.h" // NOLINT(build/include_directory)
#include "v8-maybe.h" // NOLINT(build/include_directory)
#include "v8config.h" // NOLINT(build/include_directory)
namespace v8 {
class ArrayBuffer;
class Isolate;
class Object;
class SharedArrayBuffer;
class String;
class WasmModuleObject;
class Value;
namespace internal {
struct ScriptStreamingData;
class SharedObjectConveyorHandles;
class ValueDeserializer;
class ValueSerializer;
} // namespace internal
/**
* A move-only class for managing the lifetime of shared value conveyors used
* by V8 to keep JS shared values alive in transit when serialized.
*
* This class is not directly constructible and is always passed to a
* ValueSerializer::Delegate via ValueSerializer::SetSharedValueConveyor.
*
* The embedder must not destruct the SharedValueConveyor until the associated
* serialized data will no longer be deserialized.
*/
class V8_EXPORT SharedValueConveyor final {
public:
SharedValueConveyor(SharedValueConveyor&&) noexcept;
~SharedValueConveyor();
SharedValueConveyor& operator=(SharedValueConveyor&&) noexcept;
private:
friend class internal::ValueSerializer;
friend class internal::ValueDeserializer;
explicit SharedValueConveyor(Isolate* isolate);
std::unique_ptr<internal::SharedObjectConveyorHandles> private_;
};
/**
* Value serialization compatible with the HTML structured clone algorithm.
* The format is backward-compatible (i.e. safe to store to disk).
*/
class V8_EXPORT ValueSerializer {
public:
class V8_EXPORT Delegate {
public:
virtual ~Delegate() = default;
/**
* Handles the case where a DataCloneError would be thrown in the structured
* clone spec. Other V8 embedders may throw some other appropriate exception
* type.
*/
virtual void ThrowDataCloneError(Local<String> message) = 0;
/**
* The embedder overrides this method to enable custom host object filter
* with Delegate::IsHostObject.
*
* This method is called at most once per serializer.
*/
virtual bool HasCustomHostObject(Isolate* isolate);
/**
* The embedder overrides this method to determine if an JS object is a
* host object and needs to be serialized by the host.
*/
virtual Maybe<bool> IsHostObject(Isolate* isolate, Local<Object> object);
/**
* The embedder overrides this method to write some kind of host object, if
* possible. If not, a suitable exception should be thrown and
* Nothing<bool>() returned.
*/
virtual Maybe<bool> WriteHostObject(Isolate* isolate, Local<Object> object);
/**
* Called when the ValueSerializer is going to serialize a
* SharedArrayBuffer object. The embedder must return an ID for the
* object, using the same ID if this SharedArrayBuffer has already been
* serialized in this buffer. When deserializing, this ID will be passed to
* ValueDeserializer::GetSharedArrayBufferFromId as |clone_id|.
*
* If the object cannot be serialized, an
* exception should be thrown and Nothing<uint32_t>() returned.
*/
virtual Maybe<uint32_t> GetSharedArrayBufferId(
Isolate* isolate, Local<SharedArrayBuffer> shared_array_buffer);
virtual Maybe<uint32_t> GetWasmModuleTransferId(
Isolate* isolate, Local<WasmModuleObject> module);
/**
* Called when the first shared value is serialized. All subsequent shared
* values will use the same conveyor.
*
* The embedder must ensure the lifetime of the conveyor matches the
* lifetime of the serialized data.
*
* If the embedder supports serializing shared values, this method should
* return true. Otherwise the embedder should throw an exception and return
* false.
*
* This method is called at most once per serializer.
*/
virtual bool AdoptSharedValueConveyor(Isolate* isolate,
SharedValueConveyor&& conveyor);
/**
* Allocates memory for the buffer of at least the size provided. The actual
* size (which may be greater or equal) is written to |actual_size|. If no
* buffer has been allocated yet, nullptr will be provided.
*
* If the memory cannot be allocated, nullptr should be returned.
* |actual_size| will be ignored. It is assumed that |old_buffer| is still
* valid in this case and has not been modified.
*
* The default implementation uses the stdlib's `realloc()` function.
*/
virtual void* ReallocateBufferMemory(void* old_buffer, size_t size,
size_t* actual_size);
/**
* Frees a buffer allocated with |ReallocateBufferMemory|.
*
* The default implementation uses the stdlib's `free()` function.
*/
virtual void FreeBufferMemory(void* buffer);
};
explicit ValueSerializer(Isolate* isolate);
ValueSerializer(Isolate* isolate, Delegate* delegate);
~ValueSerializer();
/**
* Writes out a header, which includes the format version.
*/
void WriteHeader();
/**
* Serializes a JavaScript value into the buffer.
*/
V8_WARN_UNUSED_RESULT Maybe<bool> WriteValue(Local<Context> context,
Local<Value> value);
/**
* Returns the stored data (allocated using the delegate's
* ReallocateBufferMemory) and its size. This serializer should not be used
* once the buffer is released. The contents are undefined if a previous write
* has failed. Ownership of the buffer is transferred to the caller.
*/
V8_WARN_UNUSED_RESULT std::pair<uint8_t*, size_t> Release();
/**
* Marks an ArrayBuffer as havings its contents transferred out of band.
* Pass the corresponding ArrayBuffer in the deserializing context to
* ValueDeserializer::TransferArrayBuffer.
*/
void TransferArrayBuffer(uint32_t transfer_id,
Local<ArrayBuffer> array_buffer);
/**
* Indicate whether to treat ArrayBufferView objects as host objects,
* i.e. pass them to Delegate::WriteHostObject. This should not be
* called when no Delegate was passed.
*
* The default is not to treat ArrayBufferViews as host objects.
*/
void SetTreatArrayBufferViewsAsHostObjects(bool mode);
/**
* Write raw data in various common formats to the buffer.
* Note that integer types are written in base-128 varint format, not with a
* binary copy. For use during an override of Delegate::WriteHostObject.
*/
void WriteUint32(uint32_t value);
void WriteUint64(uint64_t value);
void WriteDouble(double value);
void WriteRawBytes(const void* source, size_t length);
ValueSerializer(const ValueSerializer&) = delete;
void operator=(const ValueSerializer&) = delete;
private:
struct PrivateData;
PrivateData* private_;
};
/**
* Deserializes values from data written with ValueSerializer, or a compatible
* implementation.
*/
class V8_EXPORT ValueDeserializer {
public:
class V8_EXPORT Delegate {
public:
virtual ~Delegate() = default;
/**
* The embedder overrides this method to read some kind of host object, if
* possible. If not, a suitable exception should be thrown and
* MaybeLocal<Object>() returned.
*/
virtual MaybeLocal<Object> ReadHostObject(Isolate* isolate);
/**
* Get a WasmModuleObject given a transfer_id previously provided
* by ValueSerializer::Delegate::GetWasmModuleTransferId
*/
virtual MaybeLocal<WasmModuleObject> GetWasmModuleFromId(
Isolate* isolate, uint32_t transfer_id);
/**
* Get a SharedArrayBuffer given a clone_id previously provided
* by ValueSerializer::Delegate::GetSharedArrayBufferId
*/
virtual MaybeLocal<SharedArrayBuffer> GetSharedArrayBufferFromId(
Isolate* isolate, uint32_t clone_id);
/**
* Get the SharedValueConveyor previously provided by
* ValueSerializer::Delegate::AdoptSharedValueConveyor.
*/
virtual const SharedValueConveyor* GetSharedValueConveyor(Isolate* isolate);
};
ValueDeserializer(Isolate* isolate, const uint8_t* data, size_t size);
ValueDeserializer(Isolate* isolate, const uint8_t* data, size_t size,
Delegate* delegate);
~ValueDeserializer();
/**
* Reads and validates a header (including the format version).
* May, for example, reject an invalid or unsupported wire format.
*/
V8_WARN_UNUSED_RESULT Maybe<bool> ReadHeader(Local<Context> context);
/**
* Deserializes a JavaScript value from the buffer.
*/
V8_WARN_UNUSED_RESULT MaybeLocal<Value> ReadValue(Local<Context> context);
/**
* Accepts the array buffer corresponding to the one passed previously to
* ValueSerializer::TransferArrayBuffer.
*/
void TransferArrayBuffer(uint32_t transfer_id,
Local<ArrayBuffer> array_buffer);
/**
* Similar to TransferArrayBuffer, but for SharedArrayBuffer.
* The id is not necessarily in the same namespace as unshared ArrayBuffer
* objects.
*/
void TransferSharedArrayBuffer(uint32_t id,
Local<SharedArrayBuffer> shared_array_buffer);
/**
* Must be called before ReadHeader to enable support for reading the legacy
* wire format (i.e., which predates this being shipped).
*
* Don't use this unless you need to read data written by previous versions of
* blink::ScriptValueSerializer.
*/
void SetSupportsLegacyWireFormat(bool supports_legacy_wire_format);
/**
* Reads the underlying wire format version. Likely mostly to be useful to
* legacy code reading old wire format versions. Must be called after
* ReadHeader.
*/
uint32_t GetWireFormatVersion() const;
/**
* Reads raw data in various common formats to the buffer.
* Note that integer types are read in base-128 varint format, not with a
* binary copy. For use during an override of Delegate::ReadHostObject.
*/
V8_WARN_UNUSED_RESULT bool ReadUint32(uint32_t* value);
V8_WARN_UNUSED_RESULT bool ReadUint64(uint64_t* value);
V8_WARN_UNUSED_RESULT bool ReadDouble(double* value);
V8_WARN_UNUSED_RESULT bool ReadRawBytes(size_t length, const void** data);
ValueDeserializer(const ValueDeserializer&) = delete;
void operator=(const ValueDeserializer&) = delete;
private:
struct PrivateData;
PrivateData* private_;
};
} // namespace v8
#endif // INCLUDE_V8_VALUE_SERIALIZER_H_
