Add minimal error handling, fix fuzz tests

* throw exception if we cannot process the input
* fix libinfiz to compile with fuzzer sanitizer also, when desired

Author: lefticus

fuzz_test/CMakeLists.txt

@@ -9,7 +9,6 @@ target_link_libraries(
   PRIVATE infiz_options
           infiz_warnings
           libinfiz
-          -coverage
           -fsanitize=fuzzer)
 target_compile_options(fuzz_tester PRIVATE -fsanitize=fuzzer)
 

fuzz_test/fuzz_tester.cpp

@@ -6,6 +6,11 @@
 // cppcheck-suppress unusedFunction symbolName=LLVMFuzzerTestOneInput
 extern "C" auto LLVMFuzzerTestOneInput(const std::uint8_t *Data, std::size_t Size) -> int
 {
-  [[maybe_unused]] const auto result = evaluate(std::string_view(reinterpret_cast<const char *>(Data), Size));// NOLINT
+  try {
+    [[maybe_unused]] const auto result =
+      evaluate(std::string_view(reinterpret_cast<const char *>(Data), Size));// NOLINT
+  } catch (const std::runtime_error &) {
+    // malformed input, but not a memory error!
+  }
   return 0;
 }

src/libinfiz/CMakeLists.txt

@@ -9,7 +9,12 @@ add_library(libinfiz
 
 add_library(infiz::libinfiz ALIAS libinfiz)
 
-target_link_libraries(libinfiz PRIVATE infiz_options infiz_warnings)
+target_link_libraries(libinfiz PRIVATE infiz_options infiz_warnings -fsanitize=fuzzer-no-link)
+
+if (infiz_BUILD_FUZZ_TESTS)
+  target_link_libraries(libinfiz PRIVATE -fsanitize=fuzzer-no-link)
+  target_compile_options(libinfiz PRIVATE -fsanitize=fuzzer-no-link)
+endif()
 
 target_include_directories(libinfiz ${WARNING_GUARD} PUBLIC $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
                                                                   $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include>)

src/libinfiz/RationalNumber.hpp

@@ -19,7 +19,11 @@ class RationalNumber
   [[nodiscard]] constexpr auto simplify() const noexcept -> RationalNumber
   {
     const auto gcd = std::gcd(numerator, denominator);
-    return {numerator / gcd, denominator / gcd};
+    if (gcd == 0) {
+      return *this;
+    } else {
+      return { numerator / gcd, denominator / gcd };
+    }
   }
 
   [[nodiscard]] constexpr auto operator/(const RationalNumber &rhs) const noexcept -> RationalNumber

src/libinfiz/Stack.hpp

@@ -6,6 +6,7 @@
 #include <cassert>
 #include <cstddef>
 #include <vector>
+#include <stdexcept>
 
 /**
  * A Class that allows allows void * to be
@@ -21,8 +22,7 @@ template<typename Contained> class Stack
 
   auto pop() -> Contained
   {
-    // TODO is an assert the best option here?
-    assert(!data.empty());
+    if (data.empty()) { throw std::runtime_error("No elements left to pop!"); }
     Contained toReturn = data.back();
     data.pop_back();
     return toReturn;