testing: Add basic fuzz test harnesses

CMakeLists.txt

@@ -1,8 +1,10 @@
-cmake_minimum_required(VERSION 3.15.0)
+cmake_minimum_required(VERSION 3.22.0)
 
 # For MSVC RUNTIME LIBRARY, need CMP0091=NEW and cmake 3.15+
 cmake_policy(SET CMP0091 NEW)
 
+include(CMakeDependentOption)
+
 # Version info
 set(QUANTLIB_VERSION_MAJOR 1)
 set(QUANTLIB_VERSION_MINOR 32)
@@ -42,6 +44,7 @@ set(QL_INSTALL_CMAKEDIR "lib/cmake/${PACKAGE_NAME}" CACHE STRING
 option(QL_BUILD_BENCHMARK "Build benchmark" ON)
 option(QL_BUILD_EXAMPLES "Build examples" ON)
 option(QL_BUILD_TEST_SUITE "Build test suite" ON)
+cmake_dependent_option(QL_BUILD_FUZZ_TEST_SUITE "Build fuzz test suite" ON "'${CMAKE_CXX_COMPILER_ID}' MATCHES 'Clang'"  OFF)
 option(QL_ENABLE_OPENMP "Detect and use OpenMP" OFF)
 option(QL_ENABLE_PARALLEL_UNIT_TEST_RUNNER "Enable the parallel unit test runner" OFF)
 option(QL_ENABLE_SESSIONS "Singletons return different instances for different sessions" OFF)
@@ -269,6 +272,10 @@ if (QL_BUILD_TEST_SUITE OR QL_BUILD_BENCHMARK)
     add_subdirectory(test-suite)
 endif()
 
+if (QL_BUILD_FUZZ_TEST_SUITE)
+    add_subdirectory(fuzz-test-suite)
+endif()
+
 # CPack support (make package, make package_source)
 set(CPACK_PACKAGE_VERSION_MAJOR ${QUANTLIB_VERSION_MAJOR})
 set(CPACK_PACKAGE_VERSION_MINOR ${QUANTLIB_VERSION_MINOR})

fuzz-test-suite/CMakeLists.txt

@@ -0,0 +1,21 @@
+# Determine the flags for fuzzing. Use OSS-Fuzz's configuration if available, otherwise fall back to defaults.
+if(DEFINED ENV{LIB_FUZZING_ENGINE})
+    set(FUZZING_ENGINE $ENV{LIB_FUZZING_ENGINE})
+    set(FUZZING_COMPILE_FLAGS "")
+    set(FUZZING_LINK_FLAGS "${FUZZING_ENGINE}")
+else()
+    set(FUZZING_COMPILE_FLAGS "-fsanitize=fuzzer")
+    set(FUZZING_LINK_FLAGS "-fsanitize=fuzzer")
+endif()
+
+# Define the fuzz target
+add_executable(DateParserFuzzer dateparserfuzzer.cpp)
+
+# Apply the determined flags
+set_target_properties(DateParserFuzzer PROPERTIES
+    COMPILE_FLAGS "${FUZZING_COMPILE_FLAGS}"
+    LINK_FLAGS "${FUZZING_LINK_FLAGS}"
+)
+
+# Link QuantLib and any other necessary libraries
+target_link_libraries(DateParserFuzzer ql_library ${QL_THREAD_LIBRARIES})

fuzz-test-suite/dateparserfuzzer.cpp

@@ -0,0 +1,24 @@
+#include <ql/time/asx.hpp>
+#include <ql/time/date.hpp>
+#include <ql/time/ecb.hpp>
+#include <ql/time/imm.hpp>
+#include <ql/time/timeunit.hpp>
+#include <ql/utilities/dataparsers.hpp>
+#include <string>
+
+#ifndef __clang__
+#pragma message("Fuzzer headers are available from clang, other compilers have not been tested.")
+#endif
+#include <fuzzer/FuzzedDataProvider.h>
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
+    FuzzedDataProvider fdp(data, size);
+    constexpr int kMaxString = 100;
+    try {
+        (void)QuantLib::DateParser::parseFormatted(fdp.ConsumeRandomLengthString(kMaxString), "%Y-%m-%d");
+        (void)QuantLib::DateParser::parseISO(fdp.ConsumeRandomLengthString(kMaxString));
+    } catch (const std::exception& e) {
+        // Handle or ignore exceptions
+    }
+    return 0;
+}