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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
#ifndef mozilla_fuzzing_FuzzingTraits_h
#define mozilla_fuzzing_FuzzingTraits_h
#include "mozilla/Assertions.h"
#include <cmath>
#include <random>
#include <type_traits>
namespace mozilla {
namespace fuzzing {
class FuzzingTraits {
public:
static unsigned int Random(unsigned int aMax);
static bool Sometimes(unsigned int aProbability);
/**
* Frequency() defines how many mutations of a kind shall be applied to a
* target buffer by using a user definable factor. The higher the factor,
* the less mutations are being made.
*/
static size_t Frequency(const size_t aSize, const uint64_t aFactor);
static std::mt19937_64& Rng();
};
/**
* RandomNumericLimit returns either the min or max limit of an arithmetic
* data type.
*/
template <typename T>
T RandomNumericLimit() {
static_assert(std::is_arithmetic_v<T> == true,
"T must be an arithmetic type");
return FuzzingTraits::Sometimes(2) ? std::numeric_limits<T>::min()
: std::numeric_limits<T>::max();
}
/**
* RandomInteger generates negative and positive integers in 2**n increments.
*/
template <typename T>
T RandomInteger() {
static_assert(std::is_integral_v<T> == true, "T must be an integral type");
double r =
static_cast<double>(FuzzingTraits::Random((sizeof(T) * CHAR_BIT) + 1));
T x = static_cast<T>(pow(2.0, r)) - 1;
if (std::numeric_limits<T>::is_signed && FuzzingTraits::Sometimes(2)) {
return (x * -1) - 1;
}
return x;
}
/**
* RandomIntegerRange returns a random integral within a [min, max] range.
*/
template <typename T>
T RandomIntegerRange(T min, T max) {
static_assert(std::is_integral_v<T> == true, "T must be an integral type");
MOZ_ASSERT(min < max);
std::uniform_int_distribution<T> d(min, max);
return d(FuzzingTraits::Rng());
}
/**
* uniform_int_distribution is undefined for char/uchar. Need to handle them
* separately.
*/
template <>
inline unsigned char RandomIntegerRange(unsigned char min, unsigned char max) {
MOZ_ASSERT(min < max);
std::uniform_int_distribution<unsigned short> d(min, max);
return static_cast<unsigned char>(d(FuzzingTraits::Rng()));
}
template <>
inline char RandomIntegerRange(char min, char max) {
MOZ_ASSERT(min < max);
std::uniform_int_distribution<short> d(min, max);
return static_cast<char>(d(FuzzingTraits::Rng()));
}
/**
* RandomFloatingPointRange returns a random floating-point number within a
* [min, max] range.
*/
template <typename T>
T RandomFloatingPointRange(T min, T max) {
static_assert(std::is_floating_point_v<T> == true,
"T must be a floating point type");
MOZ_ASSERT(min < max);
std::uniform_real_distribution<T> d(
min, std::nextafter(max, std::numeric_limits<T>::max()));
return d(FuzzingTraits::Rng());
}
/**
* RandomFloatingPoint returns a random floating-point number in 2**n
* increments.
*/
template <typename T>
T RandomFloatingPoint() {
static_assert(std::is_floating_point_v<T> == true,
"T must be a floating point type");
int radix = RandomIntegerRange<int>(std::numeric_limits<T>::min_exponent,
std::numeric_limits<T>::max_exponent);
T x = static_cast<T>(pow(2.0, static_cast<double>(radix)));
return x * RandomFloatingPointRange<T>(-1.0, 1.0);
}
} // namespace fuzzing
} // namespace mozilla
#endif