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50 lines
2.1 KiB
C++
50 lines
2.1 KiB
C++
// Copyright (c) 2025-present The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include <test/fuzz/FuzzedDataProvider.h>
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#include <test/fuzz/fuzz.h>
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#include <util/check.h>
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#include <util/overflow.h>
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#include <algorithm>
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#include <limits>
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#include <optional>
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namespace {
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//! Test overflow operations for type T using a wider type, W, to verify results.
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template <typename T, typename W>
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void TestOverflow(FuzzedDataProvider& fuzzed_data_provider)
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{
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constexpr auto min{std::numeric_limits<T>::min()};
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constexpr auto max{std::numeric_limits<T>::max()};
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// Range needs to be at least twice as big to allow two numbers to be added without overflowing.
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static_assert(min >= std::numeric_limits<W>::min() / 2);
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static_assert(max <= std::numeric_limits<W>::max() / 2);
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auto widen = [](T value) -> W { return value; };
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auto clamp = [](W value) -> W { return std::clamp<W>(value, min, max); };
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auto check = [](W value) -> std::optional<W> { if (value >= min && value <= max) return value; else return std::nullopt; };
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const T i = fuzzed_data_provider.ConsumeIntegral<T>();
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const T j = fuzzed_data_provider.ConsumeIntegral<T>();
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const unsigned shift = fuzzed_data_provider.ConsumeIntegralInRange<unsigned>(0, std::numeric_limits<W>::digits - std::numeric_limits<T>::digits);
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Assert(clamp(widen(i) + widen(j)) == SaturatingAdd(i, j));
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Assert(check(widen(i) + widen(j)) == CheckedAdd(i, j));
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Assert(clamp(widen(i) << shift) == SaturatingLeftShift(i, shift));
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Assert(check(widen(i) << shift) == CheckedLeftShift(i, shift));
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}
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} // namespace
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FUZZ_TARGET(overflow)
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{
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FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
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TestOverflow<int8_t, int64_t>(fuzzed_data_provider);
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TestOverflow<int16_t, int64_t>(fuzzed_data_provider);
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TestOverflow<int32_t, int64_t>(fuzzed_data_provider);
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TestOverflow<uint8_t, uint64_t>(fuzzed_data_provider);
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TestOverflow<uint16_t, uint64_t>(fuzzed_data_provider);
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TestOverflow<uint32_t, uint64_t>(fuzzed_data_provider);
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}
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