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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef __IPC_GLUE_IPCMESSAGEUTILS_H__
#define __IPC_GLUE_IPCMESSAGEUTILS_H__
#include <cstdint>
#include <string>
#include <type_traits>
#include "build/build_config.h"
#include "chrome/common/ipc_message.h"
#include "chrome/common/ipc_message_utils.h"
#include "mozilla/ipc/IPCCore.h"
#include "mozilla/MacroForEach.h"
class PickleIterator;
// XXX Things that are not necessary if moving implementations to the cpp file
#include "base/string_util.h"
#ifdef _MSC_VER
# pragma warning(disable : 4800)
#endif
#if !defined(OS_POSIX)
// This condition must be kept in sync with the one in
// ipc_message_utils.h, but this dummy definition of
// base::FileDescriptor acts as a static assert that we only get one
// def or the other (or neither, in which case code using
// FileDescriptor fails to build)
namespace base {
struct FileDescriptor {};
} // namespace base
#endif
namespace mozilla {
template <typename...>
class Variant;
namespace detail {
template <typename...>
struct VariantTag;
}
} // namespace mozilla
namespace IPC {
/**
* A helper class for serializing plain-old data (POD) structures.
* The memory representation of the structure is written to and read from
* the serialized stream directly, without individual processing of the
* structure's members.
*
* Derive ParamTraits<T> from PlainOldDataSerializer<T> if T is POD.
*
* Note: For POD structures with enumeration fields, this will not do
* validation of the enum values the way serializing the fields
* individually would. Prefer serializing the fields individually
* in such cases.
*/
template <typename T>
struct PlainOldDataSerializer {
static_assert(
std::is_trivially_copyable<T>::value,
"PlainOldDataSerializer can only be used with trivially copyable types!");
typedef T paramType;
static void Write(MessageWriter* aWriter, const paramType& aParam) {
aWriter->WriteBytes(&aParam, sizeof(aParam));
}
static bool Read(MessageReader* aReader, paramType* aResult) {
return aReader->ReadBytesInto(aResult, sizeof(paramType));
}
};
/**
* A helper class for serializing empty structs. Since the struct is empty there
* is nothing to write, and a priori we know the result of the read.
*/
template <typename T>
struct EmptyStructSerializer {
typedef T paramType;
static void Write(MessageWriter* aWriter, const paramType& aParam) {}
static bool Read(MessageReader* aReader, paramType* aResult) {
*aResult = {};
return true;
}
};
template <>
struct ParamTraits<int8_t> {
typedef int8_t paramType;
static void Write(MessageWriter* aWriter, const paramType& aParam) {
aWriter->WriteBytes(&aParam, sizeof(aParam));
}
static bool Read(MessageReader* aReader, paramType* aResult) {
return aReader->ReadBytesInto(aResult, sizeof(*aResult));
}
};
template <>
struct ParamTraits<uint8_t> {
typedef uint8_t paramType;
static void Write(MessageWriter* aWriter, const paramType& aParam) {
aWriter->WriteBytes(&aParam, sizeof(aParam));
}
static bool Read(MessageReader* aReader, paramType* aResult) {
return aReader->ReadBytesInto(aResult, sizeof(*aResult));
}
};
#if !defined(OS_POSIX)
// See above re: keeping definitions in sync
template <>
struct ParamTraits<base::FileDescriptor> {
typedef base::FileDescriptor paramType;
static void Write(MessageWriter* aWriter, const paramType& aParam) {
MOZ_CRASH("FileDescriptor isn't meaningful on this platform");
}
static bool Read(MessageReader* aReader, paramType* aResult) {
MOZ_CRASH("FileDescriptor isn't meaningful on this platform");
return false;
}
};
#endif // !defined(OS_POSIX)
template <>
struct ParamTraits<mozilla::void_t> {
typedef mozilla::void_t paramType;
static void Write(MessageWriter* aWriter, const paramType& aParam) {}
static bool Read(MessageReader* aReader, paramType* aResult) {
*aResult = paramType();
return true;
}
};
template <>
struct ParamTraits<mozilla::null_t> {
typedef mozilla::null_t paramType;
static void Write(MessageWriter* aWriter, const paramType& aParam) {}
static bool Read(MessageReader* aReader, paramType* aResult) {
*aResult = paramType();
return true;
}
};
// Helper class for reading bitfields.
// If T has bitfields members, derive ParamTraits<T> from BitfieldHelper<T>.
template <typename ParamType>
struct BitfieldHelper {
// We need this helper because we can't get the address of a bitfield to
// pass directly to ReadParam. So instead we read it into a temporary bool
// and set the bitfield using a setter function
static bool ReadBoolForBitfield(MessageReader* aReader, ParamType* aResult,
void (ParamType::*aSetter)(bool)) {
bool value;
if (ReadParam(aReader, &value)) {
(aResult->*aSetter)(value);
return true;
}
return false;
}
};
// A couple of recursive helper functions, allows syntax like:
// WriteParams(aMsg, aParam.foo, aParam.bar, aParam.baz)
// ReadParams(aMsg, aIter, aParam.foo, aParam.bar, aParam.baz)
template <typename... Ts>
static void WriteParams(MessageWriter* aWriter, const Ts&... aArgs) {
(WriteParam(aWriter, aArgs), ...);
}
template <typename... Ts>
static bool ReadParams(MessageReader* aReader, Ts&... aArgs) {
return (ReadParam(aReader, &aArgs) && ...);
}
// Macros that allow syntax like:
// DEFINE_IPC_SERIALIZER_WITH_FIELDS(SomeType, member1, member2, member3)
// Makes sure that serialize/deserialize code do the same members in the same
// order.
#define ACCESS_PARAM_FIELD(Field) aParam.Field
#define DEFINE_IPC_SERIALIZER_WITH_FIELDS(Type, ...) \
template <> \
struct ParamTraits<Type> { \
typedef Type paramType; \
static void Write(MessageWriter* aWriter, const paramType& aParam) { \
WriteParams(aWriter, MOZ_FOR_EACH_SEPARATED(ACCESS_PARAM_FIELD, (, ), \
(), (__VA_ARGS__))); \
} \
\
static bool Read(MessageReader* aReader, paramType* aResult) { \
paramType& aParam = *aResult; \
return ReadParams(aReader, \
MOZ_FOR_EACH_SEPARATED(ACCESS_PARAM_FIELD, (, ), (), \
(__VA_ARGS__))); \
} \
};
#define DEFINE_IPC_SERIALIZER_WITHOUT_FIELDS(Type) \
template <> \
struct ParamTraits<Type> : public EmptyStructSerializer<Type> {};
} /* namespace IPC */
#define DEFINE_IPC_SERIALIZER_WITH_SUPER_CLASS_AND_FIELDS(Type, Super, ...) \
template <> \
struct ParamTraits<Type> { \
typedef Type paramType; \
static void Write(MessageWriter* aWriter, const paramType& aParam) { \
WriteParam(aWriter, static_cast<const Super&>(aParam)); \
WriteParams(aWriter, MOZ_FOR_EACH_SEPARATED(ACCESS_PARAM_FIELD, (, ), \
(), (__VA_ARGS__))); \
} \
\
static bool Read(MessageReader* aReader, paramType* aResult) { \
paramType& aParam = *aResult; \
return ReadParam(aReader, static_cast<Super*>(aResult)) && \
ReadParams(aReader, \
MOZ_FOR_EACH_SEPARATED(ACCESS_PARAM_FIELD, (, ), (), \
(__VA_ARGS__))); \
} \
};
#endif /* __IPC_GLUE_IPCMESSAGEUTILS_H__ */
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