Initialer commit.

Makefile

+
+CXXFLAGS=-std=c++17
+
+default: main
+
+fuzz_main: main.cpp
+	afl-g++ $(CXXFLAGS) -o fuzz_main main.cpp
+
+fuzz: fuzz_main
+	rm -rf out
+	afl-fuzz -i in -o out -- ./fuzz_main
+
+clean:
+	rm -rf main fuzz_main out

default.nix

+with import (import ./nixpkgs.nix) {};
+stdenv.mkDerivation {
+  name = "fuzzer-example";
+  src = ./.;
+  nativeBuildInputs = [ afl ];
+
+  installPhase = ''
+    mkdir -p $out
+    find . -executable -type f -exec cp {} $out \;
+  '';
+}

in/a.txt

+11+3+2/

in/b.txt

+11/

main.cpp

+#include <iostream>
+#include <optional>
+#include <stack>
+#include <stdexcept>
+#include <climits>
+#include <unordered_map>
+#include <iterator>
+
+std::stack<int> stack;
+
+int plus(int a, int b) {
+	return a + b;
+}
+
+int minus(int a, int b) {
+	return b - a;
+}
+
+int produkt(int a, int b) {
+	return a * b;
+}
+
+int division(int a, int b) {
+	if (b == 0) {
+		throw std::invalid_argument("Division durch 0!");
+	}
+	return a / b;
+}
+
+std::unordered_map<char, decltype(&plus)> map {
+	{'+', plus},
+	{'-', minus},
+	{'*', produkt},
+	{'/', division}
+};
+
+int evaluate(const std::string &s) {
+	int a,b;
+	std::unordered_map<char, decltype(&plus)>::iterator iter;
+	for (char c : s) {
+		if (std::isdigit(c)) {
+			stack.push(c - '0');
+		} else {
+			if (stack.size() >= 2 ) {
+				iter = map.find(c);
+				if (iter != map.end()) {
+					a = stack.top();
+					stack.pop();
+					b = stack.top();
+					stack.pop();
+					stack.push(iter->second(b, a));
+				} else {
+					throw std::invalid_argument("Ungueltige Sonderzeichen");
+				}
+			} else {
+				throw std::invalid_argument("Ungueltige Anzahl an Zahlen");
+			}
+		}
+		/*switch (c) {
+			case '+':
+				if (stack.size() >= 2) {
+					a = stack.top();
+					stack.pop();
+					b = stack.top();
+					stack.pop();
+					stack.push(a + b);
+				}
+				break;
+			case '-':
+				if (stack.size() >= 2) {
+					a = stack.top();
+					stack.pop();
+					b = stack.top();
+					stack.pop();stack.push(b - a);
+				}
+				break;
+			case '*':
+				if (stack.size() >= 2) {
+					a = stack.top();
+					stack.pop();
+					b = stack.top();
+					stack.pop();stack.push(a * b);
+				}
+				break;
+			case '/':
+				if (stack.size() >= 2) {
+					a = stack.top();
+					stack.pop();
+					b = stack.top();
+					if (a == 0) {
+						throw std::invalid_argument("Division durch 0!");
+					}
+					stack.pop();stack.push(b / a);
+				}
+				break;
+			default:
+				if (std::isdigit(c)) {
+					stack.push(c - '0');
+				}
+				break;
+		}*/
+		
+	}
+	if (stack.size() > 1 || stack.size() == 0) {
+		throw std::invalid_argument("Ungueltige Eingabe");
+	}
+	return stack.top();
+}
+
+int main() {
+  std::string user_input;
+  std::cin >> user_input;
+
+  if (user_input.empty()) { std::cout << "Empty input\n"; return 1; }
+
+  std::cout << "User input is \"" << user_input << "\"\n";
+
+	int result = INT_MAX;
+
+	try {
+		result = evaluate(user_input);
+	} catch (const std::exception &e) {
+		std::cout << e.what();
+	}
+	if (result != INT_MAX) {
+		std::cout << "Result is: " << result << '\n';		
+	}
+    
+}

nixpkgs.nix

+builtins.fetchTarball {
+  url = "https://github.com/nixos/nixpkgs/archive/859ce47b023d80ccbcf446a112c813972a5949b6.tar.gz";
+  sha256 = "14rmrpzbxbf8p4v70n39bvxm9qhnwlg4pjkzf7ya6n697g8yd1wx";
+}

result

+/nix/store/d9ricvlvw0lq3zkyd905k8fir4zlhzcq-fuzzer-example
\ No newline at end of file