mirror of
https://github.com/mozilla/gecko-dev.git
synced 2024-10-31 22:25:30 +00:00
2824b29025
This patch was mostly generated by running the following scripts on the codebase, with some
manual changes made afterwards:
# static_assert.sh
#!/bin/bash
# Command to convert an NSPR integer type to the equivalent standard integer type
function convert() {
echo "Converting $1 to $2..."
find . ! -wholename "*nsprpub*" \
! -wholename "*security/nss*" \
! -wholename "*/.hg*" \
! -wholename "obj-ff-dbg*" \
! -name nsXPCOMCID.h \
! -name prtypes.h \
-type f \
\( -iname "*.cpp" \
-o -iname "*.h" \
-o -iname "*.cc" \
-o -iname "*.mm" \) | \
xargs -n 1 `dirname $0`/assert_replacer.py #sed -i -e "s/\b$1\b/$2/g"
}
convert MOZ_STATIC_ASSERT static_assert
hg rev --no-backup mfbt/Assertions.h \
media/webrtc/signaling/src/sipcc/core/includes/ccapi.h \
modules/libmar/src/mar_private.h \
modules/libmar/src/mar.h
# assert_replacer.py
#!/usr/bin/python
import sys
import re
pattern = re.compile(r"\bMOZ_STATIC_ASSERT\b")
def replaceInPlace(fname):
print fname
f = open(fname, "rw+")
lines = f.readlines()
for i in range(0, len(lines)):
while True:
index = re.search(pattern, lines[i])
if index != None:
index = index.start()
lines[i] = lines[i][0:index] + "static_assert" + lines[i][index+len("MOZ_STATIC_ASSERT"):]
for j in range(i + 1, len(lines)):
if lines[j].find(" ", index) == index:
lines[j] = lines[j][0:index] + lines[j][index+4:]
else:
break
else:
break
f.seek(0, 0)
f.truncate()
f.write("".join(lines))
f.close()
argc = len(sys.argv)
for i in range(1, argc):
replaceInPlace(sys.argv[i])
--HG--
extra : rebase_source : 4b4a4047d82f2c205b9fad8d56dfc3f1afc0b045
879 lines
24 KiB
C++
879 lines
24 KiB
C++
/* -*- 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/. */
|
|
|
|
/* Provides checked integers, detecting integer overflow and divide-by-0. */
|
|
|
|
#ifndef mozilla_CheckedInt_h
|
|
#define mozilla_CheckedInt_h
|
|
|
|
// Enable relying of Mozilla's MFBT for possibly-available C++11 features
|
|
#define MOZ_CHECKEDINT_USE_MFBT
|
|
|
|
#include <stdint.h>
|
|
|
|
#ifdef MOZ_CHECKEDINT_USE_MFBT
|
|
# include "mozilla/Assertions.h"
|
|
#else
|
|
# include <cassert>
|
|
# define MOZ_ASSERT(cond, reason) assert((cond) && reason)
|
|
# define MOZ_DELETE
|
|
#endif
|
|
|
|
#include <climits>
|
|
#include <cstddef>
|
|
|
|
namespace mozilla {
|
|
|
|
template<typename T> class CheckedInt;
|
|
|
|
namespace detail {
|
|
|
|
/*
|
|
* Step 1: manually record supported types
|
|
*
|
|
* What's nontrivial here is that there are different families of integer
|
|
* types: basic integer types and stdint types. It is merrily undefined which
|
|
* types from one family may be just typedefs for a type from another family.
|
|
*
|
|
* For example, on GCC 4.6, aside from the basic integer types, the only other
|
|
* type that isn't just a typedef for some of them, is int8_t.
|
|
*/
|
|
|
|
struct UnsupportedType {};
|
|
|
|
template<typename IntegerType>
|
|
struct IsSupportedPass2
|
|
{
|
|
static const bool value = false;
|
|
};
|
|
|
|
template<typename IntegerType>
|
|
struct IsSupported
|
|
{
|
|
static const bool value = IsSupportedPass2<IntegerType>::value;
|
|
};
|
|
|
|
template<>
|
|
struct IsSupported<int8_t>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupported<uint8_t>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupported<int16_t>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupported<uint16_t>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupported<int32_t>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupported<uint32_t>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupported<int64_t>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupported<uint64_t>
|
|
{ static const bool value = true; };
|
|
|
|
|
|
template<>
|
|
struct IsSupportedPass2<char>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupportedPass2<signed char>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupportedPass2<unsigned char>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupportedPass2<short>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupportedPass2<unsigned short>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupportedPass2<int>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupportedPass2<unsigned int>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupportedPass2<long>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupportedPass2<unsigned long>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupportedPass2<long long>
|
|
{ static const bool value = true; };
|
|
|
|
template<>
|
|
struct IsSupportedPass2<unsigned long long>
|
|
{ static const bool value = true; };
|
|
|
|
/*
|
|
* Step 2: some integer-traits kind of stuff.
|
|
*/
|
|
|
|
template<size_t Size, bool Signedness>
|
|
struct StdintTypeForSizeAndSignedness
|
|
{};
|
|
|
|
template<>
|
|
struct StdintTypeForSizeAndSignedness<1, true>
|
|
{ typedef int8_t Type; };
|
|
|
|
template<>
|
|
struct StdintTypeForSizeAndSignedness<1, false>
|
|
{ typedef uint8_t Type; };
|
|
|
|
template<>
|
|
struct StdintTypeForSizeAndSignedness<2, true>
|
|
{ typedef int16_t Type; };
|
|
|
|
template<>
|
|
struct StdintTypeForSizeAndSignedness<2, false>
|
|
{ typedef uint16_t Type; };
|
|
|
|
template<>
|
|
struct StdintTypeForSizeAndSignedness<4, true>
|
|
{ typedef int32_t Type; };
|
|
|
|
template<>
|
|
struct StdintTypeForSizeAndSignedness<4, false>
|
|
{ typedef uint32_t Type; };
|
|
|
|
template<>
|
|
struct StdintTypeForSizeAndSignedness<8, true>
|
|
{ typedef int64_t Type; };
|
|
|
|
template<>
|
|
struct StdintTypeForSizeAndSignedness<8, false>
|
|
{ typedef uint64_t Type; };
|
|
|
|
template<typename IntegerType>
|
|
struct UnsignedType
|
|
{
|
|
typedef typename StdintTypeForSizeAndSignedness<sizeof(IntegerType),
|
|
false>::Type Type;
|
|
};
|
|
|
|
template<typename IntegerType>
|
|
struct IsSigned
|
|
{
|
|
static const bool value = IntegerType(-1) <= IntegerType(0);
|
|
};
|
|
|
|
template<typename IntegerType, size_t Size = sizeof(IntegerType)>
|
|
struct TwiceBiggerType
|
|
{
|
|
typedef typename StdintTypeForSizeAndSignedness<
|
|
sizeof(IntegerType) * 2,
|
|
IsSigned<IntegerType>::value
|
|
>::Type Type;
|
|
};
|
|
|
|
template<typename IntegerType>
|
|
struct TwiceBiggerType<IntegerType, 8>
|
|
{
|
|
typedef UnsupportedType Type;
|
|
};
|
|
|
|
template<typename IntegerType>
|
|
struct PositionOfSignBit
|
|
{
|
|
static const size_t value = CHAR_BIT * sizeof(IntegerType) - 1;
|
|
};
|
|
|
|
template<typename IntegerType>
|
|
struct MinValue
|
|
{
|
|
private:
|
|
typedef typename UnsignedType<IntegerType>::Type UnsignedIntegerType;
|
|
static const size_t PosOfSignBit = PositionOfSignBit<IntegerType>::value;
|
|
|
|
public:
|
|
// Bitwise ops may return a larger type, that's why we cast explicitly.
|
|
// In C++, left bit shifts on signed values is undefined by the standard
|
|
// unless the shifted value is representable.
|
|
// Notice that signed-to-unsigned conversions are always well-defined in
|
|
// the standard as the value congruent to 2**n, as expected. By contrast,
|
|
// unsigned-to-signed is only well-defined if the value is representable.
|
|
static const IntegerType value =
|
|
IsSigned<IntegerType>::value
|
|
? IntegerType(UnsignedIntegerType(1) << PosOfSignBit)
|
|
: IntegerType(0);
|
|
};
|
|
|
|
template<typename IntegerType>
|
|
struct MaxValue
|
|
{
|
|
// Tricksy, but covered by the unit test.
|
|
// Relies heavily on the type of MinValue<IntegerType>::value
|
|
// being IntegerType.
|
|
static const IntegerType value = ~MinValue<IntegerType>::value;
|
|
};
|
|
|
|
/*
|
|
* Step 3: Implement the actual validity checks.
|
|
*
|
|
* Ideas taken from IntegerLib, code different.
|
|
*/
|
|
|
|
template<typename T>
|
|
inline bool
|
|
HasSignBit(T x)
|
|
{
|
|
// In C++, right bit shifts on negative values is undefined by the standard.
|
|
// Notice that signed-to-unsigned conversions are always well-defined in the
|
|
// standard, as the value congruent modulo 2**n as expected. By contrast,
|
|
// unsigned-to-signed is only well-defined if the value is representable.
|
|
return bool(typename UnsignedType<T>::Type(x)
|
|
>> PositionOfSignBit<T>::value);
|
|
}
|
|
|
|
// Bitwise ops may return a larger type, so it's good to use this inline
|
|
// helper guaranteeing that the result is really of type T.
|
|
template<typename T>
|
|
inline T
|
|
BinaryComplement(T x)
|
|
{
|
|
return ~x;
|
|
}
|
|
|
|
template<typename T,
|
|
typename U,
|
|
bool IsTSigned = IsSigned<T>::value,
|
|
bool IsUSigned = IsSigned<U>::value>
|
|
struct DoesRangeContainRange
|
|
{
|
|
};
|
|
|
|
template<typename T, typename U, bool Signedness>
|
|
struct DoesRangeContainRange<T, U, Signedness, Signedness>
|
|
{
|
|
static const bool value = sizeof(T) >= sizeof(U);
|
|
};
|
|
|
|
template<typename T, typename U>
|
|
struct DoesRangeContainRange<T, U, true, false>
|
|
{
|
|
static const bool value = sizeof(T) > sizeof(U);
|
|
};
|
|
|
|
template<typename T, typename U>
|
|
struct DoesRangeContainRange<T, U, false, true>
|
|
{
|
|
static const bool value = false;
|
|
};
|
|
|
|
template<typename T,
|
|
typename U,
|
|
bool IsTSigned = IsSigned<T>::value,
|
|
bool IsUSigned = IsSigned<U>::value,
|
|
bool DoesTRangeContainURange = DoesRangeContainRange<T, U>::value>
|
|
struct IsInRangeImpl {};
|
|
|
|
template<typename T, typename U, bool IsTSigned, bool IsUSigned>
|
|
struct IsInRangeImpl<T, U, IsTSigned, IsUSigned, true>
|
|
{
|
|
static bool run(U)
|
|
{
|
|
return true;
|
|
}
|
|
};
|
|
|
|
template<typename T, typename U>
|
|
struct IsInRangeImpl<T, U, true, true, false>
|
|
{
|
|
static bool run(U x)
|
|
{
|
|
return x <= MaxValue<T>::value && x >= MinValue<T>::value;
|
|
}
|
|
};
|
|
|
|
template<typename T, typename U>
|
|
struct IsInRangeImpl<T, U, false, false, false>
|
|
{
|
|
static bool run(U x)
|
|
{
|
|
return x <= MaxValue<T>::value;
|
|
}
|
|
};
|
|
|
|
template<typename T, typename U>
|
|
struct IsInRangeImpl<T, U, true, false, false>
|
|
{
|
|
static bool run(U x)
|
|
{
|
|
return sizeof(T) > sizeof(U) || x <= U(MaxValue<T>::value);
|
|
}
|
|
};
|
|
|
|
template<typename T, typename U>
|
|
struct IsInRangeImpl<T, U, false, true, false>
|
|
{
|
|
static bool run(U x)
|
|
{
|
|
return sizeof(T) >= sizeof(U)
|
|
? x >= 0
|
|
: x >= 0 && x <= U(MaxValue<T>::value);
|
|
}
|
|
};
|
|
|
|
template<typename T, typename U>
|
|
inline bool
|
|
IsInRange(U x)
|
|
{
|
|
return IsInRangeImpl<T, U>::run(x);
|
|
}
|
|
|
|
template<typename T>
|
|
inline bool
|
|
IsAddValid(T x, T y)
|
|
{
|
|
// Addition is valid if the sign of x+y is equal to either that of x or that
|
|
// of y. Since the value of x+y is undefined if we have a signed type, we
|
|
// compute it using the unsigned type of the same size.
|
|
// Beware! These bitwise operations can return a larger integer type,
|
|
// if T was a small type like int8_t, so we explicitly cast to T.
|
|
|
|
typename UnsignedType<T>::Type ux = x;
|
|
typename UnsignedType<T>::Type uy = y;
|
|
typename UnsignedType<T>::Type result = ux + uy;
|
|
return IsSigned<T>::value
|
|
? HasSignBit(BinaryComplement(T((result ^ x) & (result ^ y))))
|
|
: BinaryComplement(x) >= y;
|
|
}
|
|
|
|
template<typename T>
|
|
inline bool
|
|
IsSubValid(T x, T y)
|
|
{
|
|
// Subtraction is valid if either x and y have same sign, or x-y and x have
|
|
// same sign. Since the value of x-y is undefined if we have a signed type,
|
|
// we compute it using the unsigned type of the same size.
|
|
typename UnsignedType<T>::Type ux = x;
|
|
typename UnsignedType<T>::Type uy = y;
|
|
typename UnsignedType<T>::Type result = ux - uy;
|
|
|
|
return IsSigned<T>::value
|
|
? HasSignBit(BinaryComplement(T((result ^ x) & (x ^ y))))
|
|
: x >= y;
|
|
}
|
|
|
|
template<typename T,
|
|
bool IsTSigned = IsSigned<T>::value,
|
|
bool TwiceBiggerTypeIsSupported =
|
|
IsSupported<typename TwiceBiggerType<T>::Type>::value>
|
|
struct IsMulValidImpl {};
|
|
|
|
template<typename T, bool IsTSigned>
|
|
struct IsMulValidImpl<T, IsTSigned, true>
|
|
{
|
|
static bool run(T x, T y)
|
|
{
|
|
typedef typename TwiceBiggerType<T>::Type TwiceBiggerType;
|
|
TwiceBiggerType product = TwiceBiggerType(x) * TwiceBiggerType(y);
|
|
return IsInRange<T>(product);
|
|
}
|
|
};
|
|
|
|
template<typename T>
|
|
struct IsMulValidImpl<T, true, false>
|
|
{
|
|
static bool run(T x, T y)
|
|
{
|
|
const T max = MaxValue<T>::value;
|
|
const T min = MinValue<T>::value;
|
|
|
|
if (x == 0 || y == 0)
|
|
return true;
|
|
|
|
if (x > 0) {
|
|
return y > 0
|
|
? x <= max / y
|
|
: y >= min / x;
|
|
}
|
|
|
|
// If we reach this point, we know that x < 0.
|
|
return y > 0
|
|
? x >= min / y
|
|
: y >= max / x;
|
|
}
|
|
};
|
|
|
|
template<typename T>
|
|
struct IsMulValidImpl<T, false, false>
|
|
{
|
|
static bool run(T x, T y)
|
|
{
|
|
return y == 0 || x <= MaxValue<T>::value / y;
|
|
}
|
|
};
|
|
|
|
template<typename T>
|
|
inline bool
|
|
IsMulValid(T x, T y)
|
|
{
|
|
return IsMulValidImpl<T>::run(x, y);
|
|
}
|
|
|
|
template<typename T>
|
|
inline bool
|
|
IsDivValid(T x, T y)
|
|
{
|
|
// Keep in mind that in the signed case, min/-1 is invalid because abs(min)>max.
|
|
return y != 0 &&
|
|
!(IsSigned<T>::value && x == MinValue<T>::value && y == T(-1));
|
|
}
|
|
|
|
template<typename T, bool IsTSigned = IsSigned<T>::value>
|
|
struct IsModValidImpl;
|
|
|
|
template<typename T>
|
|
inline bool
|
|
IsModValid(T x, T y)
|
|
{
|
|
return IsModValidImpl<T>::run(x, y);
|
|
}
|
|
|
|
/*
|
|
* Mod is pretty simple.
|
|
* For now, let's just use the ANSI C definition:
|
|
* If x or y are negative, the results are implementation defined.
|
|
* Consider these invalid.
|
|
* Undefined for y=0.
|
|
* The result will never exceed either x or y.
|
|
*
|
|
* Checking that x>=0 is a warning when T is unsigned.
|
|
*/
|
|
|
|
template<typename T>
|
|
struct IsModValidImpl<T, false> {
|
|
static inline bool run(T x, T y) {
|
|
return y >= 1;
|
|
}
|
|
};
|
|
|
|
template<typename T>
|
|
struct IsModValidImpl<T, true> {
|
|
static inline bool run(T x, T y) {
|
|
if (x < 0)
|
|
return false;
|
|
|
|
return y >= 1;
|
|
}
|
|
};
|
|
|
|
template<typename T, bool IsSigned = IsSigned<T>::value>
|
|
struct NegateImpl;
|
|
|
|
template<typename T>
|
|
struct NegateImpl<T, false>
|
|
{
|
|
static CheckedInt<T> negate(const CheckedInt<T>& val)
|
|
{
|
|
// Handle negation separately for signed/unsigned, for simpler code and to
|
|
// avoid an MSVC warning negating an unsigned value.
|
|
return CheckedInt<T>(0, val.isValid() && val.mValue == 0);
|
|
}
|
|
};
|
|
|
|
template<typename T>
|
|
struct NegateImpl<T, true>
|
|
{
|
|
static CheckedInt<T> negate(const CheckedInt<T>& val)
|
|
{
|
|
// Watch out for the min-value, which (with twos-complement) can't be
|
|
// negated as -min-value is then (max-value + 1).
|
|
if (!val.isValid() || val.mValue == MinValue<T>::value)
|
|
return CheckedInt<T>(val.mValue, false);
|
|
return CheckedInt<T>(-val.mValue, true);
|
|
}
|
|
};
|
|
|
|
} // namespace detail
|
|
|
|
|
|
/*
|
|
* Step 4: Now define the CheckedInt class.
|
|
*/
|
|
|
|
/**
|
|
* @class CheckedInt
|
|
* @brief Integer wrapper class checking for integer overflow and other errors
|
|
* @param T the integer type to wrap. Can be any type among the following:
|
|
* - any basic integer type such as |int|
|
|
* - any stdint type such as |int8_t|
|
|
*
|
|
* This class implements guarded integer arithmetic. Do a computation, check
|
|
* that isValid() returns true, you then have a guarantee that no problem, such
|
|
* as integer overflow, happened during this computation, and you can call
|
|
* value() to get the plain integer value.
|
|
*
|
|
* The arithmetic operators in this class are guaranteed not to raise a signal
|
|
* (e.g. in case of a division by zero).
|
|
*
|
|
* For example, suppose that you want to implement a function that computes
|
|
* (x+y)/z, that doesn't crash if z==0, and that reports on error (divide by
|
|
* zero or integer overflow). You could code it as follows:
|
|
@code
|
|
bool computeXPlusYOverZ(int x, int y, int z, int *result)
|
|
{
|
|
CheckedInt<int> checkedResult = (CheckedInt<int>(x) + y) / z;
|
|
if (checkedResult.isValid()) {
|
|
*result = checkedResult.value();
|
|
return true;
|
|
} else {
|
|
return false;
|
|
}
|
|
}
|
|
@endcode
|
|
*
|
|
* Implicit conversion from plain integers to checked integers is allowed. The
|
|
* plain integer is checked to be in range before being casted to the
|
|
* destination type. This means that the following lines all compile, and the
|
|
* resulting CheckedInts are correctly detected as valid or invalid:
|
|
* @code
|
|
// 1 is of type int, is found to be in range for uint8_t, x is valid
|
|
CheckedInt<uint8_t> x(1);
|
|
// -1 is of type int, is found not to be in range for uint8_t, x is invalid
|
|
CheckedInt<uint8_t> x(-1);
|
|
// -1 is of type int, is found to be in range for int8_t, x is valid
|
|
CheckedInt<int8_t> x(-1);
|
|
// 1000 is of type int16_t, is found not to be in range for int8_t,
|
|
// x is invalid
|
|
CheckedInt<int8_t> x(int16_t(1000));
|
|
// 3123456789 is of type uint32_t, is found not to be in range for int32_t,
|
|
// x is invalid
|
|
CheckedInt<int32_t> x(uint32_t(3123456789));
|
|
* @endcode
|
|
* Implicit conversion from
|
|
* checked integers to plain integers is not allowed. As shown in the
|
|
* above example, to get the value of a checked integer as a normal integer,
|
|
* call value().
|
|
*
|
|
* Arithmetic operations between checked and plain integers is allowed; the
|
|
* result type is the type of the checked integer.
|
|
*
|
|
* Checked integers of different types cannot be used in the same arithmetic
|
|
* expression.
|
|
*
|
|
* There are convenience typedefs for all stdint types, of the following form
|
|
* (these are just 2 examples):
|
|
@code
|
|
typedef CheckedInt<int32_t> CheckedInt32;
|
|
typedef CheckedInt<uint16_t> CheckedUint16;
|
|
@endcode
|
|
*/
|
|
template<typename T>
|
|
class CheckedInt
|
|
{
|
|
protected:
|
|
T mValue;
|
|
bool mIsValid;
|
|
|
|
template<typename U>
|
|
CheckedInt(U value, bool isValid) : mValue(value), mIsValid(isValid)
|
|
{
|
|
static_assert(detail::IsSupported<T>::value &&
|
|
detail::IsSupported<U>::value,
|
|
"This type is not supported by CheckedInt");
|
|
}
|
|
|
|
friend struct detail::NegateImpl<T>;
|
|
|
|
public:
|
|
/**
|
|
* Constructs a checked integer with given @a value. The checked integer is
|
|
* initialized as valid or invalid depending on whether the @a value
|
|
* is in range.
|
|
*
|
|
* This constructor is not explicit. Instead, the type of its argument is a
|
|
* separate template parameter, ensuring that no conversion is performed
|
|
* before this constructor is actually called. As explained in the above
|
|
* documentation for class CheckedInt, this constructor checks that its
|
|
* argument is valid.
|
|
*/
|
|
template<typename U>
|
|
CheckedInt(U value)
|
|
: mValue(T(value)),
|
|
mIsValid(detail::IsInRange<T>(value))
|
|
{
|
|
static_assert(detail::IsSupported<T>::value &&
|
|
detail::IsSupported<U>::value,
|
|
"This type is not supported by CheckedInt");
|
|
}
|
|
|
|
template<typename U>
|
|
friend class CheckedInt;
|
|
|
|
template<typename U>
|
|
CheckedInt<U> toChecked() const
|
|
{
|
|
CheckedInt<U> ret(mValue);
|
|
ret.mIsValid = ret.mIsValid && mIsValid;
|
|
return ret;
|
|
}
|
|
|
|
/** Constructs a valid checked integer with initial value 0 */
|
|
CheckedInt() : mValue(0), mIsValid(true)
|
|
{
|
|
static_assert(detail::IsSupported<T>::value,
|
|
"This type is not supported by CheckedInt");
|
|
}
|
|
|
|
/** @returns the actual value */
|
|
T value() const
|
|
{
|
|
MOZ_ASSERT(mIsValid, "Invalid checked integer (division by zero or integer overflow)");
|
|
return mValue;
|
|
}
|
|
|
|
/**
|
|
* @returns true if the checked integer is valid, i.e. is not the result
|
|
* of an invalid operation or of an operation involving an invalid checked
|
|
* integer
|
|
*/
|
|
bool isValid() const
|
|
{
|
|
return mIsValid;
|
|
}
|
|
|
|
template<typename U>
|
|
friend CheckedInt<U> operator +(const CheckedInt<U>& lhs,
|
|
const CheckedInt<U>& rhs);
|
|
template<typename U>
|
|
CheckedInt& operator +=(U rhs);
|
|
|
|
template<typename U>
|
|
friend CheckedInt<U> operator -(const CheckedInt<U>& lhs,
|
|
const CheckedInt<U>& rhs);
|
|
template<typename U>
|
|
CheckedInt& operator -=(U rhs);
|
|
|
|
template<typename U>
|
|
friend CheckedInt<U> operator *(const CheckedInt<U>& lhs,
|
|
const CheckedInt<U>& rhs);
|
|
template<typename U>
|
|
CheckedInt& operator *=(U rhs);
|
|
|
|
template<typename U>
|
|
friend CheckedInt<U> operator /(const CheckedInt<U>& lhs,
|
|
const CheckedInt<U>& rhs);
|
|
template<typename U>
|
|
CheckedInt& operator /=(U rhs);
|
|
|
|
template<typename U>
|
|
friend CheckedInt<U> operator %(const CheckedInt<U>& lhs,
|
|
const CheckedInt<U>& rhs);
|
|
template<typename U>
|
|
CheckedInt& operator %=(U rhs);
|
|
|
|
CheckedInt operator -() const
|
|
{
|
|
return detail::NegateImpl<T>::negate(*this);
|
|
}
|
|
|
|
/**
|
|
* @returns true if the left and right hand sides are valid
|
|
* and have the same value.
|
|
*
|
|
* Note that these semantics are the reason why we don't offer
|
|
* a operator!=. Indeed, we'd want to have a!=b be equivalent to !(a==b)
|
|
* but that would mean that whenever a or b is invalid, a!=b
|
|
* is always true, which would be very confusing.
|
|
*
|
|
* For similar reasons, operators <, >, <=, >= would be very tricky to
|
|
* specify, so we just avoid offering them.
|
|
*
|
|
* Notice that these == semantics are made more reasonable by these facts:
|
|
* 1. a==b implies equality at the raw data level
|
|
* (the converse is false, as a==b is never true among invalids)
|
|
* 2. This is similar to the behavior of IEEE floats, where a==b
|
|
* means that a and b have the same value *and* neither is NaN.
|
|
*/
|
|
bool operator ==(const CheckedInt& other) const
|
|
{
|
|
return mIsValid && other.mIsValid && mValue == other.mValue;
|
|
}
|
|
|
|
/** prefix ++ */
|
|
CheckedInt& operator++()
|
|
{
|
|
*this += 1;
|
|
return *this;
|
|
}
|
|
|
|
/** postfix ++ */
|
|
CheckedInt operator++(int)
|
|
{
|
|
CheckedInt tmp = *this;
|
|
*this += 1;
|
|
return tmp;
|
|
}
|
|
|
|
/** prefix -- */
|
|
CheckedInt& operator--()
|
|
{
|
|
*this -= 1;
|
|
return *this;
|
|
}
|
|
|
|
/** postfix -- */
|
|
CheckedInt operator--(int)
|
|
{
|
|
CheckedInt tmp = *this;
|
|
*this -= 1;
|
|
return tmp;
|
|
}
|
|
|
|
private:
|
|
/**
|
|
* The !=, <, <=, >, >= operators are disabled:
|
|
* see the comment on operator==.
|
|
*/
|
|
template<typename U>
|
|
bool operator !=(U other) const MOZ_DELETE;
|
|
template<typename U>
|
|
bool operator <(U other) const MOZ_DELETE;
|
|
template<typename U>
|
|
bool operator <=(U other) const MOZ_DELETE;
|
|
template<typename U>
|
|
bool operator >(U other) const MOZ_DELETE;
|
|
template<typename U>
|
|
bool operator >=(U other) const MOZ_DELETE;
|
|
};
|
|
|
|
#define MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR(NAME, OP) \
|
|
template<typename T> \
|
|
inline CheckedInt<T> operator OP(const CheckedInt<T> &lhs, \
|
|
const CheckedInt<T> &rhs) \
|
|
{ \
|
|
if (!detail::Is##NAME##Valid(lhs.mValue, rhs.mValue)) \
|
|
return CheckedInt<T>(0, false); \
|
|
\
|
|
return CheckedInt<T>(lhs.mValue OP rhs.mValue, \
|
|
lhs.mIsValid && rhs.mIsValid); \
|
|
}
|
|
|
|
MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR(Add, +)
|
|
MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR(Sub, -)
|
|
MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR(Mul, *)
|
|
MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR(Div, /)
|
|
MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR(Mod, %)
|
|
|
|
#undef MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR
|
|
|
|
// Implement castToCheckedInt<T>(x), making sure that
|
|
// - it allows x to be either a CheckedInt<T> or any integer type
|
|
// that can be casted to T
|
|
// - if x is already a CheckedInt<T>, we just return a reference to it,
|
|
// instead of copying it (optimization)
|
|
|
|
namespace detail {
|
|
|
|
template<typename T, typename U>
|
|
struct CastToCheckedIntImpl
|
|
{
|
|
typedef CheckedInt<T> ReturnType;
|
|
static CheckedInt<T> run(U u) { return u; }
|
|
};
|
|
|
|
template<typename T>
|
|
struct CastToCheckedIntImpl<T, CheckedInt<T> >
|
|
{
|
|
typedef const CheckedInt<T>& ReturnType;
|
|
static const CheckedInt<T>& run(const CheckedInt<T>& u) { return u; }
|
|
};
|
|
|
|
} // namespace detail
|
|
|
|
template<typename T, typename U>
|
|
inline typename detail::CastToCheckedIntImpl<T, U>::ReturnType
|
|
castToCheckedInt(U u)
|
|
{
|
|
static_assert(detail::IsSupported<T>::value &&
|
|
detail::IsSupported<U>::value,
|
|
"This type is not supported by CheckedInt");
|
|
return detail::CastToCheckedIntImpl<T, U>::run(u);
|
|
}
|
|
|
|
#define MOZ_CHECKEDINT_CONVENIENCE_BINARY_OPERATORS(OP, COMPOUND_OP) \
|
|
template<typename T> \
|
|
template<typename U> \
|
|
CheckedInt<T>& CheckedInt<T>::operator COMPOUND_OP(U rhs) \
|
|
{ \
|
|
*this = *this OP castToCheckedInt<T>(rhs); \
|
|
return *this; \
|
|
} \
|
|
template<typename T, typename U> \
|
|
inline CheckedInt<T> operator OP(const CheckedInt<T> &lhs, U rhs) \
|
|
{ \
|
|
return lhs OP castToCheckedInt<T>(rhs); \
|
|
} \
|
|
template<typename T, typename U> \
|
|
inline CheckedInt<T> operator OP(U lhs, const CheckedInt<T> &rhs) \
|
|
{ \
|
|
return castToCheckedInt<T>(lhs) OP rhs; \
|
|
}
|
|
|
|
MOZ_CHECKEDINT_CONVENIENCE_BINARY_OPERATORS(+, +=)
|
|
MOZ_CHECKEDINT_CONVENIENCE_BINARY_OPERATORS(*, *=)
|
|
MOZ_CHECKEDINT_CONVENIENCE_BINARY_OPERATORS(-, -=)
|
|
MOZ_CHECKEDINT_CONVENIENCE_BINARY_OPERATORS(/, /=)
|
|
MOZ_CHECKEDINT_CONVENIENCE_BINARY_OPERATORS(%, %=)
|
|
|
|
#undef MOZ_CHECKEDINT_CONVENIENCE_BINARY_OPERATORS
|
|
|
|
template<typename T, typename U>
|
|
inline bool
|
|
operator ==(const CheckedInt<T> &lhs, U rhs)
|
|
{
|
|
return lhs == castToCheckedInt<T>(rhs);
|
|
}
|
|
|
|
template<typename T, typename U>
|
|
inline bool
|
|
operator ==(U lhs, const CheckedInt<T> &rhs)
|
|
{
|
|
return castToCheckedInt<T>(lhs) == rhs;
|
|
}
|
|
|
|
// Convenience typedefs.
|
|
typedef CheckedInt<int8_t> CheckedInt8;
|
|
typedef CheckedInt<uint8_t> CheckedUint8;
|
|
typedef CheckedInt<int16_t> CheckedInt16;
|
|
typedef CheckedInt<uint16_t> CheckedUint16;
|
|
typedef CheckedInt<int32_t> CheckedInt32;
|
|
typedef CheckedInt<uint32_t> CheckedUint32;
|
|
typedef CheckedInt<int64_t> CheckedInt64;
|
|
typedef CheckedInt<uint64_t> CheckedUint64;
|
|
|
|
} // namespace mozilla
|
|
|
|
#endif /* mozilla_CheckedInt_h */
|