Revision control
++ // Copyright (C) 2020 Intel Corporation.
++ // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
++ // Qt-Security score:critical reason:cryptography
++
++ #ifndef QRANDOM_H
++ #define QRANDOM_H
++
++ #include <QtCore/qalgorithms.h>
++ #include <algorithm> // for std::generate
++ #include <random> // for std::mt19937
++
++ #ifdef min
++ # undef min
++ #endif
++ #ifdef max
++ # undef max
++ #endif
++
++ QT_BEGIN_NAMESPACE
++
++ class QRandomGenerator
++ {
++ // restrict the template parameters to unsigned integers 32 bits wide or larger
++ template <typename UInt> using IfValidUInt =
++ typename std::enable_if<std::is_unsigned<UInt>::value && sizeof(UInt) >= sizeof(uint), bool>::type;
++ public:
++ QRandomGenerator(quint32 seedValue = 1)
++ : QRandomGenerator(&seedValue, 1)
++ {}
++ template <qsizetype N> QRandomGenerator(const quint32 (&seedBuffer)[N])
++ : QRandomGenerator(seedBuffer, seedBuffer + N)
++ {}
++ QRandomGenerator(const quint32 *seedBuffer, qsizetype len)
++ : QRandomGenerator(seedBuffer, seedBuffer + len)
++ {}
++ Q_CORE_EXPORT QRandomGenerator(std::seed_seq &sseq) noexcept;
++ Q_CORE_EXPORT QRandomGenerator(const quint32 *begin, const quint32 *end);
++
++ // copy constructor & assignment operator (move unnecessary)
++ Q_CORE_EXPORT QRandomGenerator(const QRandomGenerator &other);
++ Q_CORE_EXPORT QRandomGenerator &operator=(const QRandomGenerator &other);
++
++ ~QRandomGenerator() = default;
++
++ friend Q_CORE_EXPORT bool operator==(const QRandomGenerator &rng1, const QRandomGenerator &rng2);
++ friend bool operator!=(const QRandomGenerator &rng1, const QRandomGenerator &rng2)
++ {
++ return !(rng1 == rng2);
++ }
++
++ quint32 generate()
++ {
++ return quint32(_fillRange(nullptr, 1));
++ }
++
++ quint64 generate64()
++ {
++ return _fillRange(nullptr, sizeof(quint64) / sizeof(quint32));
++ }
++
++ double generateDouble()
++ {
++ // IEEE 754 double precision has:
++ // 1 bit sign
++ // 10 bits exponent
++ // 53 bits mantissa
++ // In order for our result to be normalized in the range [0, 1), we
++ // need exactly 53 bits of random data. Use generate64() to get enough.
++ quint64 x = generate64();
++ quint64 limit = Q_UINT64_C(1) << std::numeric_limits<double>::digits;
++ x >>= std::numeric_limits<quint64>::digits - std::numeric_limits<double>::digits;
++ return double(x) / double(limit);
++ }
++
++ double bounded(double highest)
++ {
++ return generateDouble() * highest;
++ }
++
++ quint32 bounded(quint32 highest)
++ {
++ quint64 value = generate();
++ value *= highest;
++ value /= (max)() + quint64(1);
++ return quint32(value);
++ }
++
++ quint32 bounded(quint32 lowest, quint32 highest)
++ {
++ Q_ASSERT(highest > lowest);
++ return bounded(highest - lowest) + lowest;
++ }
++
++ int bounded(int highest)
++ {
++ Q_ASSERT(highest > 0);
++ return int(bounded(0U, quint32(highest)));
++ }
++
++ int bounded(int lowest, int highest)
++ {
++ return bounded(highest - lowest) + lowest;
++ }
++
++ quint64 bounded(quint64 highest);
++
++ quint64 bounded(quint64 lowest, quint64 highest)
++ {
++ Q_ASSERT(highest > lowest);
++ return bounded(highest - lowest) + lowest;
++ }
++
++ qint64 bounded(qint64 highest)
++ {
++ Q_ASSERT(highest > 0);
++ return qint64(bounded(quint64(0), quint64(highest)));
++ }
++
++ qint64 bounded(qint64 lowest, qint64 highest)
++ {
++ return bounded(highest - lowest) + lowest;
++ }
++
++ // these functions here only to help with ambiguous overloads
++ qint64 bounded(int lowest, qint64 highest)
++ {
++ return bounded(qint64(lowest), qint64(highest));
++ }
++ qint64 bounded(qint64 lowest, int highest)
++ {
++ return bounded(qint64(lowest), qint64(highest));
++ }
++
++ quint64 bounded(unsigned lowest, quint64 highest)
++ {
++ return bounded(quint64(lowest), quint64(highest));
++ }
++ quint64 bounded(quint64 lowest, unsigned highest)
++ {
++ return bounded(quint64(lowest), quint64(highest));
++ }
++
++ template <typename UInt, IfValidUInt<UInt> = true>
++ void fillRange(UInt *buffer, qsizetype count)
++ {
++ _fillRange(buffer, count * sizeof(UInt) / sizeof(quint32));
++ }
++
++ template <typename UInt, size_t N, IfValidUInt<UInt> = true>
++ void fillRange(UInt (&buffer)[N])
++ {
++ _fillRange(buffer, N * sizeof(UInt) / sizeof(quint32));
++ }
++
++ // API like std::seed_seq
++ template <typename ForwardIterator>
++ void generate(ForwardIterator begin, ForwardIterator end)
++ {
++ std::generate(begin, end, [this]() { return generate(); });
++ }
++
++ void generate(quint32 *begin, quint32 *end)
++ {
++ _fillRange(begin, end - begin);
++ }
++
++ // API like std:: random engines
++ typedef quint32 result_type;
++ result_type operator()() { return generate(); }
++ void seed(quint32 s = 1) { *this = { s }; }
++ void seed(std::seed_seq &sseq) noexcept { *this = { sseq }; }
++ Q_CORE_EXPORT void discard(unsigned long long z);
++ static constexpr result_type min() { return (std::numeric_limits<result_type>::min)(); }
++ static constexpr result_type max() { return (std::numeric_limits<result_type>::max)(); }
++
++ static inline Q_DECL_CONST_FUNCTION QRandomGenerator *system();
++ static inline Q_DECL_CONST_FUNCTION QRandomGenerator *global();
++ static inline QRandomGenerator securelySeeded();
++
++ protected:
++ enum System {};
++ QRandomGenerator(System);
++
++ private:
++ Q_CORE_EXPORT quint64 _fillRange(void *buffer, qptrdiff count);
++
++ struct InitialRandomData {
++ quintptr data[16 / sizeof(quintptr)];
++ };
++ friend InitialRandomData qt_initial_random_value() noexcept;
++ friend class QRandomGenerator64;
++ struct SystemGenerator;
++ struct SystemAndGlobalGenerators;
++ using RandomEngine = std::mersenne_twister_engine<quint32,
++ 32,624,397,31,0x9908b0df,11,0xffffffff,7,0x9d2c5680,15,0xefc60000,18,1812433253>;
++
++ union Storage {
++ uint dummy;
++ RandomEngine twister;
++ RandomEngine &engine() { return twister; }
++ const RandomEngine &engine() const { return twister; }
++
++ static_assert(std::is_trivially_destructible<RandomEngine>::value,
++ "std::mersenne_twister not trivially destructible as expected");
++ constexpr Storage();
++ };
++ uint type;
++ Storage storage;
++ };
++
++ class QRandomGenerator64 : public QRandomGenerator
++ {
++ QRandomGenerator64(System);
++ public:
++ // unshadow generate() overloads, since we'll override.
++ using QRandomGenerator::generate;
++ quint64 generate() { return generate64(); }
++
++ typedef quint64 result_type;
++ result_type operator()() { return generate64(); }
++
++ #ifndef Q_QDOC
++ QRandomGenerator64(quint32 seedValue = 1)
++ : QRandomGenerator(seedValue)
++ {}
++ template <qsizetype N> QRandomGenerator64(const quint32 (&seedBuffer)[N])
++ : QRandomGenerator(seedBuffer)
++ {}
++ QRandomGenerator64(const quint32 *seedBuffer, qsizetype len)
++ : QRandomGenerator(seedBuffer, len)
++ {}
++ QRandomGenerator64(std::seed_seq &sseq) noexcept
++ : QRandomGenerator(sseq)
++ {}
++ QRandomGenerator64(const quint32 *begin, const quint32 *end)
++ : QRandomGenerator(begin, end)
++ {}
++ QRandomGenerator64(const QRandomGenerator &other) : QRandomGenerator(other) {}
++
++ void discard(unsigned long long z)
++ {
++ Q_ASSERT_X(z * 2 > z, "QRandomGenerator64::discard",
++ "Overflow. Are you sure you want to skip over 9 quintillion samples?");
++ QRandomGenerator::discard(z * 2);
++ }
++
++ static constexpr result_type min() { return (std::numeric_limits<result_type>::min)(); }
++ static constexpr result_type max() { return (std::numeric_limits<result_type>::max)(); }
++ static Q_DECL_CONST_FUNCTION Q_CORE_EXPORT QRandomGenerator64 *system();
++ static Q_DECL_CONST_FUNCTION Q_CORE_EXPORT QRandomGenerator64 *global();
++ static Q_CORE_EXPORT QRandomGenerator64 securelySeeded();
++ #endif // Q_QDOC
++ };
++
++ inline quint64 QRandomGenerator::bounded(quint64 highest)
++ {
++ // Implement an algorithm similar to libc++'s uniform_int_distribution:
++ // loop around getting a random number, mask off any bits that "highest"
++ // will never need, then check if it's higher than "highest". The number of
++ // times the loop will run is unbounded but the probability of terminating
++ // is better than 1/2 on each iteration. Therefore, the average loop count
++ // should be less than 2.
++
++ const int width = qCountLeadingZeroBits(highest - 1);
++ const quint64 mask = (quint64(1) << (std::numeric_limits<quint64>::digits - width)) - 1;
++ quint64 v;
++ do {
++ v = generate64() & mask;
++ } while (v >= highest);
++ return v;
++ }
++
++ inline QRandomGenerator *QRandomGenerator::system()
++ {
++ return QRandomGenerator64::system();
++ }
++
++ inline QRandomGenerator *QRandomGenerator::global()
++ {
++ return QRandomGenerator64::global();
++ }
++
++ QRandomGenerator QRandomGenerator::securelySeeded()
++ {
++ return QRandomGenerator64::securelySeeded();
++ }
++
++ QT_END_NAMESPACE
++
++ #endif // QRANDOM_H