tests: Add fuzzing harness for MultiplicationOverflow(...)

1 files changed, 42 insertions, 0 deletions

diff --git a/src/test/fuzz/multiplication_overflow.cpp b/src/test/fuzz/multiplication_overflow.cpp
new file mode 100644
index 0000000000..923db8058b
--- /dev/null
+++ b/src/test/fuzz/multiplication_overflow.cpp
@@ -0,0 +1,42 @@
+// Copyright (c) 2020 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <test/fuzz/FuzzedDataProvider.h>
+#include <test/fuzz/fuzz.h>
+#include <test/fuzz/util.h>
+
+#include <cstdint>
+#include <string>
+#include <vector>
+
+namespace {
+template <typename T>
+void TestMultiplicationOverflow(FuzzedDataProvider& fuzzed_data_provider)
+{
+    const T i = fuzzed_data_provider.ConsumeIntegral<T>();
+    const T j = fuzzed_data_provider.ConsumeIntegral<T>();
+    const bool is_multiplication_overflow_custom = MultiplicationOverflow(i, j);
+    T result_builtin;
+    const bool is_multiplication_overflow_builtin = __builtin_mul_overflow(i, j, &result_builtin);
+    assert(is_multiplication_overflow_custom == is_multiplication_overflow_builtin);
+    if (!is_multiplication_overflow_custom) {
+        assert(i * j == result_builtin);
+    }
+}
+} // namespace
+
+void test_one_input(const std::vector<uint8_t>& buffer)
+{
+    FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
+    TestMultiplicationOverflow<int64_t>(fuzzed_data_provider);
+    TestMultiplicationOverflow<uint64_t>(fuzzed_data_provider);
+    TestMultiplicationOverflow<int32_t>(fuzzed_data_provider);
+    TestMultiplicationOverflow<uint32_t>(fuzzed_data_provider);
+    TestMultiplicationOverflow<int16_t>(fuzzed_data_provider);
+    TestMultiplicationOverflow<uint16_t>(fuzzed_data_provider);
+    TestMultiplicationOverflow<char>(fuzzed_data_provider);
+    TestMultiplicationOverflow<unsigned char>(fuzzed_data_provider);
+    TestMultiplicationOverflow<signed char>(fuzzed_data_provider);
+    TestMultiplicationOverflow<bool>(fuzzed_data_provider);
+}