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Diffstat (limited to 'security/sandbox/chromium/base/numerics/safe_math_shared_impl.h')
| -rw-r--r-- | security/sandbox/chromium/base/numerics/safe_math_shared_impl.h | 240 |
1 files changed, 240 insertions, 0 deletions
diff --git a/security/sandbox/chromium/base/numerics/safe_math_shared_impl.h b/security/sandbox/chromium/base/numerics/safe_math_shared_impl.h new file mode 100644 index 0000000000..3556b1ea81 --- /dev/null +++ b/security/sandbox/chromium/base/numerics/safe_math_shared_impl.h @@ -0,0 +1,240 @@ +// Copyright 2017 The Chromium 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 BASE_NUMERICS_SAFE_MATH_SHARED_IMPL_H_ +#define BASE_NUMERICS_SAFE_MATH_SHARED_IMPL_H_ + +#include <stddef.h> +#include <stdint.h> + +#include <cassert> +#include <climits> +#include <cmath> +#include <cstdlib> +#include <limits> +#include <type_traits> + +#include "base/numerics/safe_conversions.h" + +#ifdef __asmjs__ +// Optimized safe math instructions are incompatible with asmjs. +#define BASE_HAS_OPTIMIZED_SAFE_MATH (0) +// Where available use builtin math overflow support on Clang and GCC. +#elif !defined(__native_client__) && \ + ((defined(__clang__) && \ + ((__clang_major__ > 3) || \ + (__clang_major__ == 3 && __clang_minor__ >= 4))) || \ + (defined(__GNUC__) && __GNUC__ >= 5)) +#include "base/numerics/safe_math_clang_gcc_impl.h" +#define BASE_HAS_OPTIMIZED_SAFE_MATH (1) +#else +#define BASE_HAS_OPTIMIZED_SAFE_MATH (0) +#endif + +namespace base { +namespace internal { + +// These are the non-functioning boilerplate implementations of the optimized +// safe math routines. +#if !BASE_HAS_OPTIMIZED_SAFE_MATH +template <typename T, typename U> +struct CheckedAddFastOp { + static const bool is_supported = false; + template <typename V> + static constexpr bool Do(T, U, V*) { + // Force a compile failure if instantiated. + return CheckOnFailure::template HandleFailure<bool>(); + } +}; + +template <typename T, typename U> +struct CheckedSubFastOp { + static const bool is_supported = false; + template <typename V> + static constexpr bool Do(T, U, V*) { + // Force a compile failure if instantiated. + return CheckOnFailure::template HandleFailure<bool>(); + } +}; + +template <typename T, typename U> +struct CheckedMulFastOp { + static const bool is_supported = false; + template <typename V> + static constexpr bool Do(T, U, V*) { + // Force a compile failure if instantiated. + return CheckOnFailure::template HandleFailure<bool>(); + } +}; + +template <typename T, typename U> +struct ClampedAddFastOp { + static const bool is_supported = false; + template <typename V> + static constexpr V Do(T, U) { + // Force a compile failure if instantiated. + return CheckOnFailure::template HandleFailure<V>(); + } +}; + +template <typename T, typename U> +struct ClampedSubFastOp { + static const bool is_supported = false; + template <typename V> + static constexpr V Do(T, U) { + // Force a compile failure if instantiated. + return CheckOnFailure::template HandleFailure<V>(); + } +}; + +template <typename T, typename U> +struct ClampedMulFastOp { + static const bool is_supported = false; + template <typename V> + static constexpr V Do(T, U) { + // Force a compile failure if instantiated. + return CheckOnFailure::template HandleFailure<V>(); + } +}; + +template <typename T> +struct ClampedNegFastOp { + static const bool is_supported = false; + static constexpr T Do(T) { + // Force a compile failure if instantiated. + return CheckOnFailure::template HandleFailure<T>(); + } +}; +#endif // BASE_HAS_OPTIMIZED_SAFE_MATH +#undef BASE_HAS_OPTIMIZED_SAFE_MATH + +// This is used for UnsignedAbs, where we need to support floating-point +// template instantiations even though we don't actually support the operations. +// However, there is no corresponding implementation of e.g. SafeUnsignedAbs, +// so the float versions will not compile. +template <typename Numeric, + bool IsInteger = std::is_integral<Numeric>::value, + bool IsFloat = std::is_floating_point<Numeric>::value> +struct UnsignedOrFloatForSize; + +template <typename Numeric> +struct UnsignedOrFloatForSize<Numeric, true, false> { + using type = typename std::make_unsigned<Numeric>::type; +}; + +template <typename Numeric> +struct UnsignedOrFloatForSize<Numeric, false, true> { + using type = Numeric; +}; + +// Wrap the unary operations to allow SFINAE when instantiating integrals versus +// floating points. These don't perform any overflow checking. Rather, they +// exhibit well-defined overflow semantics and rely on the caller to detect +// if an overflow occured. + +template <typename T, + typename std::enable_if<std::is_integral<T>::value>::type* = nullptr> +constexpr T NegateWrapper(T value) { + using UnsignedT = typename std::make_unsigned<T>::type; + // This will compile to a NEG on Intel, and is normal negation on ARM. + return static_cast<T>(UnsignedT(0) - static_cast<UnsignedT>(value)); +} + +template < + typename T, + typename std::enable_if<std::is_floating_point<T>::value>::type* = nullptr> +constexpr T NegateWrapper(T value) { + return -value; +} + +template <typename T, + typename std::enable_if<std::is_integral<T>::value>::type* = nullptr> +constexpr typename std::make_unsigned<T>::type InvertWrapper(T value) { + return ~value; +} + +template <typename T, + typename std::enable_if<std::is_integral<T>::value>::type* = nullptr> +constexpr T AbsWrapper(T value) { + return static_cast<T>(SafeUnsignedAbs(value)); +} + +template < + typename T, + typename std::enable_if<std::is_floating_point<T>::value>::type* = nullptr> +constexpr T AbsWrapper(T value) { + return value < 0 ? -value : value; +} + +template <template <typename, typename, typename> class M, + typename L, + typename R> +struct MathWrapper { + using math = M<typename UnderlyingType<L>::type, + typename UnderlyingType<R>::type, + void>; + using type = typename math::result_type; +}; + +// These variadic templates work out the return types. +// TODO(jschuh): Rip all this out once we have C++14 non-trailing auto support. +template <template <typename, typename, typename> class M, + typename L, + typename R, + typename... Args> +struct ResultType; + +template <template <typename, typename, typename> class M, + typename L, + typename R> +struct ResultType<M, L, R> { + using type = typename MathWrapper<M, L, R>::type; +}; + +template <template <typename, typename, typename> class M, + typename L, + typename R, + typename... Args> +struct ResultType { + using type = + typename ResultType<M, typename ResultType<M, L, R>::type, Args...>::type; +}; + +// The following macros are just boilerplate for the standard arithmetic +// operator overloads and variadic function templates. A macro isn't the nicest +// solution, but it beats rewriting these over and over again. +#define BASE_NUMERIC_ARITHMETIC_VARIADIC(CLASS, CL_ABBR, OP_NAME) \ + template <typename L, typename R, typename... Args> \ + constexpr CLASS##Numeric< \ + typename ResultType<CLASS##OP_NAME##Op, L, R, Args...>::type> \ + CL_ABBR##OP_NAME(const L lhs, const R rhs, const Args... args) { \ + return CL_ABBR##MathOp<CLASS##OP_NAME##Op, L, R, Args...>(lhs, rhs, \ + args...); \ + } + +#define BASE_NUMERIC_ARITHMETIC_OPERATORS(CLASS, CL_ABBR, OP_NAME, OP, CMP_OP) \ + /* Binary arithmetic operator for all CLASS##Numeric operations. */ \ + template <typename L, typename R, \ + typename std::enable_if<Is##CLASS##Op<L, R>::value>::type* = \ + nullptr> \ + constexpr CLASS##Numeric< \ + typename MathWrapper<CLASS##OP_NAME##Op, L, R>::type> \ + operator OP(const L lhs, const R rhs) { \ + return decltype(lhs OP rhs)::template MathOp<CLASS##OP_NAME##Op>(lhs, \ + rhs); \ + } \ + /* Assignment arithmetic operator implementation from CLASS##Numeric. */ \ + template <typename L> \ + template <typename R> \ + constexpr CLASS##Numeric<L>& CLASS##Numeric<L>::operator CMP_OP( \ + const R rhs) { \ + return MathOp<CLASS##OP_NAME##Op>(rhs); \ + } \ + /* Variadic arithmetic functions that return CLASS##Numeric. */ \ + BASE_NUMERIC_ARITHMETIC_VARIADIC(CLASS, CL_ABBR, OP_NAME) + +} // namespace internal +} // namespace base + +#endif // BASE_NUMERICS_SAFE_MATH_SHARED_IMPL_H_ |