Source code
Revision control
Copy as Markdown
Other Tools
/* -*- 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
#ifndef __IPC_GLUE_ENUMSERIALIZER_H__
#define __IPC_GLUE_ENUMSERIALIZER_H__
#include "CrashAnnotations.h"
#include "chrome/common/ipc_message_utils.h"
#include "mozilla/Assertions.h"
#include "mozilla/IntegerTypeTraits.h"
#include "nsExceptionHandler.h"
#include "nsLiteralString.h"
#include "nsString.h"
#include "nsTLiteralString.h"
class PickleIterator;
namespace IPC {
class Message;
class MessageReader;
class MessageWriter;
} // namespace IPC
#ifdef _MSC_VER
# pragma warning(disable : 4800)
#endif
namespace IPC {
/**
* Generic enum serializer.
*
* Consider using the specializations below, such as ContiguousEnumSerializer.
*
* This is a generic serializer for any enum type used in IPDL.
* Programmers can define ParamTraits<E> for enum type E by deriving
* EnumSerializer<E, MyEnumValidator> where MyEnumValidator is a struct
* that has to define a static IsLegalValue function returning whether
* a given value is a legal value of the enum type at hand.
*
*/
template <typename E, typename EnumValidator>
struct EnumSerializer {
typedef E paramType;
// std::make_unsigned_t<std::underlying_type_t<paramType>>, to make this more
// consistent with the type used for validating values?
typedef typename mozilla::UnsignedStdintTypeForSize<sizeof(paramType)>::Type
uintParamType;
static void Write(MessageWriter* aWriter, const paramType& aValue) {
// XXX This assertion is somewhat meaningless at least for E that don't have
// a fixed underlying type: if aValue weren't a legal value, we would
// already have UB where this function is called.
MOZ_RELEASE_ASSERT(EnumValidator::IsLegalValue(
static_cast<std::underlying_type_t<paramType>>(aValue)));
WriteParam(aWriter, uintParamType(aValue));
}
static bool Read(MessageReader* aReader, paramType* aResult) {
uintParamType value;
if (!ReadParam(aReader, &value)) {
CrashReporter::RecordAnnotationCString(
CrashReporter::Annotation::IPCReadErrorReason, "Bad iter");
return false;
}
if (!EnumValidator::IsLegalValue(value)) {
CrashReporter::RecordAnnotationCString(
CrashReporter::Annotation::IPCReadErrorReason, "Illegal value");
return false;
}
*aResult = paramType(value);
return true;
}
};
template <typename E, E MinLegal, E HighBound>
class ContiguousEnumValidator {
// Silence overzealous -Wtype-limits bug in GCC fixed in GCC 4.8:
// "comparison of unsigned expression >= 0 is always true"
template <typename T>
static bool IsLessThanOrEqual(T a, T b) {
return a <= b;
}
public:
using IntegralType = std::underlying_type_t<E>;
static constexpr auto kMinLegalIntegral = static_cast<IntegralType>(MinLegal);
static constexpr auto kHighBoundIntegral =
static_cast<IntegralType>(HighBound);
static bool IsLegalValue(const IntegralType e) {
return IsLessThanOrEqual(kMinLegalIntegral, e) && e < kHighBoundIntegral;
}
};
template <typename E, E MinLegal, E MaxLegal>
class ContiguousEnumValidatorInclusive {
// Silence overzealous -Wtype-limits bug in GCC fixed in GCC 4.8:
// "comparison of unsigned expression >= 0 is always true"
template <typename T>
static bool IsLessThanOrEqual(T a, T b) {
return a <= b;
}
public:
using IntegralType = std::underlying_type_t<E>;
static constexpr auto kMinLegalIntegral = static_cast<IntegralType>(MinLegal);
static constexpr auto kMaxLegalIntegral = static_cast<IntegralType>(MaxLegal);
static bool IsLegalValue(const IntegralType e) {
return IsLessThanOrEqual(kMinLegalIntegral, e) && e <= kMaxLegalIntegral;
}
};
template <typename E, E AllBits>
struct BitFlagsEnumValidator {
static bool IsLegalValue(const std::underlying_type_t<E> e) {
return (e & static_cast<std::underlying_type_t<E>>(AllBits)) == e;
}
};
/**
* Specialization of EnumSerializer for enums with contiguous enum values.
*
* Provide two values: MinLegal, HighBound. An enum value x will be
* considered legal if MinLegal <= x < HighBound.
*
* For example, following is definition of serializer for enum type FOO.
* \code
* enum FOO { FOO_FIRST, FOO_SECOND, FOO_LAST, NUM_FOO };
*
* template <>
* struct ParamTraits<FOO>:
* public ContiguousEnumSerializer<FOO, FOO_FIRST, NUM_FOO> {};
* \endcode
* FOO_FIRST, FOO_SECOND, and FOO_LAST are valid value.
*/
template <typename E, E MinLegal, E HighBound>
struct ContiguousEnumSerializer
: EnumSerializer<E, ContiguousEnumValidator<E, MinLegal, HighBound>> {};
/**
* This is similar to ContiguousEnumSerializer, but the last template
* parameter is expected to be the highest legal value, rather than a
* sentinel value. This is intended to support enumerations that don't
* have sentinel values.
*/
template <typename E, E MinLegal, E MaxLegal>
struct ContiguousEnumSerializerInclusive
: EnumSerializer<E,
ContiguousEnumValidatorInclusive<E, MinLegal, MaxLegal>> {
};
/**
* Specialization of EnumSerializer for enums representing bit flags.
*
* Provide one value: AllBits. An enum value x will be
* considered legal if (x & AllBits) == x;
*
* Example:
* \code
* enum FOO {
* FOO_FIRST = 1 << 0,
* FOO_SECOND = 1 << 1,
* FOO_LAST = 1 << 2,
* ALL_BITS = (1 << 3) - 1
* };
*
* template <>
* struct ParamTraits<FOO>:
* public BitFlagsEnumSerializer<FOO, FOO::ALL_BITS> {};
* \endcode
*/
template <typename E, E AllBits>
struct BitFlagsEnumSerializer
: EnumSerializer<E, BitFlagsEnumValidator<E, AllBits>> {};
} /* namespace IPC */
#endif /* __IPC_GLUE_ENUMSERIALIZER_H__ */