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// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef MOJO_PUBLIC_CPP_BASE_PROTO_WRAPPER_H_
#define MOJO_PUBLIC_CPP_BASE_PROTO_WRAPPER_H_
#include <optional>
#include <string>
#include "base/component_export.h"
#include "base/containers/span.h"
#include "base/gtest_prod_util.h"
#include "mojo/public/cpp/base/big_buffer.h"
#include "mojo/public/cpp/base/proto_wrapper_passkeys.h"
#include "mojo/public/cpp/bindings/default_construct_tag.h"
namespace google::protobuf {
class MessageLite;
} // namespace google::protobuf
namespace mojo_base {
namespace mojom {
class ProtoWrapperDataView;
} // namespace mojom
template <typename T>
concept IsProtoMessage =
!std::is_abstract<T>() &&
std::is_base_of<google::protobuf::MessageLite, T>::value;
class COMPONENT_EXPORT(MOJO_BASE_PROTOBUF_SUPPORT) ProtoWrapper {
public:
ProtoWrapper(ProtoWrapper&& other);
ProtoWrapper& operator=(ProtoWrapper&& other);
ProtoWrapper(const ProtoWrapper&) = delete;
ProtoWrapper& operator=(const ProtoWrapper&) = delete;
~ProtoWrapper();
// Exposed so mojo can create this class.
explicit ProtoWrapper(mojo::DefaultConstruct::Tag passkey);
// Construct from a protobuf message. May CHECK if the message fails
// serialization. Once constructed the message can be discarded. The typename
// of the message is stored along with the bytes that serialize the message,
// and must match the typename of the message this wrapper is deserialized to.
explicit ProtoWrapper(const google::protobuf::MessageLite& message);
// Construct from an already serialized proto stream - only use this if the
// stream has come from an external source (e.g. the network, an OS service)
// and you need to get the message into the mojo IPC system with a typename.
// This constructor does not validate that the stream of bytes can populate
// its wrapped protobuf Message until an unwrapping is attempted.
// Makes a copy of the data in the provided span.
explicit ProtoWrapper(base::span<const uint8_t> data,
std::string type_name,
base::PassKey<ProtoWrapperBytes> passkey);
template <IsProtoMessage ProtoMessage>
std::optional<ProtoMessage> As() const {
ProtoMessage message;
if (DeserializeToMessage(message)) {
return message;
}
return std::nullopt;
}
// Access this to store the bytes somewhere else, or pass to another IPC
// system. The bytes may be mapped from a hostile process so while the size
// cannot change, the contents might. If you want to unpack the contained
// protobuf Message, use As<T>();
std::optional<base::span<const uint8_t>> byte_span(
base::PassKey<ProtoWrapperBytes> passkey) const {
if (!is_valid()) {
return std::nullopt;
}
return base::span(*bytes_);
}
private:
friend struct mojo::StructTraits<mojo_base::mojom::ProtoWrapperDataView,
mojo_base::ProtoWrapper>;
FRIEND_TEST_ALL_PREFIXES(ProtoWrapperTest, TraitsOk);
FRIEND_TEST_ALL_PREFIXES(ProtoWrapperTest, LargeMessage);
FRIEND_TEST_ALL_PREFIXES(ProtoWrapperTest, TraitsEquivilentMessages);
FRIEND_TEST_ALL_PREFIXES(ProtoWrapperTest, TraitsDistinctMessages);
FRIEND_TEST_ALL_PREFIXES(ProtoWrapperTest, ToFromBytes);
// Prevent creation of invalid wrappers.
ProtoWrapper();
// is_valid() implies the wrapper wraps some data - it does not mean that the
// bytes will deserialize to a valid message.
bool is_valid() const { return bytes_.has_value(); }
bool DeserializeToMessage(google::protobuf::MessageLite& message) const;
std::string proto_name_;
std::optional<BigBuffer> bytes_;
};
} // namespace mojo_base
#endif // MOJO_PUBLIC_CPP_BASE_PROTO_WRAPPER_H_
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