this should merge

Author: Don Johnson

a.cpp

@@ -1,92 +1,48 @@
 #include <iostream>
-#include <string>
-#include <vector>
-#include <algorithm>
-#include <sstream>
+#include <string_view>
+#include <cstdlib>
+#include <stdexcept>
 
-/**
- * Example "allowlist" of shell commands permitted by this program.
- * In real-world usage, you'd carefully design or omit this approach
- * to avoid potential command injection altogether.
- */
-static const std::vector<std::string> ALLOWED_COMMANDS = {
-    "ls",      // List directory
-    "pwd",     // Print working directory
-    "whoami",  // Show current user
-    // Add others only if absolutely necessary
-};
-
-/**
- * Splits a string into tokens, e.g. "ls -l /home" -> ["ls", "-l", "/home"].
- * Helps us separate the base command from its arguments.
- */
-std::vector<std::string> tokenize(const std::string &input) {
-    std::vector<std::string> tokens;
-    std::istringstream iss(input);
-    std::string token;
-    while (iss >> token) {
-        tokens.push_back(token);
-    }
-    return tokens;
-}
-
-/**
- * Checks if a given command (the first token) is in the ALLOWED_COMMANDS.
- */
-bool is_base_command_allowed(const std::string &cmd) {
-    return std::find(ALLOWED_COMMANDS.begin(), ALLOWED_COMMANDS.end(), cmd)
-           != ALLOWED_COMMANDS.end();
-}
+namespace app {
 
-int main() {
-    std::cout << "Enter a shell command to run (allowed: ls, pwd, whoami): ";
+class Greeter {
+public:
+    // Use string_view for efficient string passing
+    explicit Greeter(std::string_view message) noexcept
+        : m_message(message) {}
 
-    // Safely read user input into a std::string
-    std::string userInput;
-    if (!std::getline(std::cin, userInput)) {
-        std::cerr << "Error reading input or EOF reached.\n";
-        return 1;
+    // Mark member functions that don't modify state as const
+    [[nodiscard]] auto getMessage() const noexcept -> std::string_view {
+        return m_message;
     }
 
-    // Tokenize the input: first token is the base command; subsequent tokens are arguments
-    std::vector<std::string> tokens = tokenize(userInput);
-    if (tokens.empty()) {
-        std::cerr << "No command entered.\n";
-        return 1;
+    // Use auto return type for better maintainability
+    auto greet() const -> void {
+        std::cout << getMessage() << '\n';
     }
 
-    // The first token (base command) must match our allowlist
-    const std::string &baseCmd = tokens[0];
-    if (!is_base_command_allowed(baseCmd)) {
-        std::cerr << "[SECURITY] Denied: Command \"" << baseCmd << "\" is not in the allowed list.\n";
-        return 1;
-    }
-
-    // Optional: further checks on arguments if you want to allow only certain flags, etc.
-    // For example:
-    //   for (size_t i = 1; i < tokens.size(); i++) {
-    //       // Validate each token carefully
-    //   }
+private:
+    std::string_view m_message;
+};
 
-    // Construct a sanitized command string for system()
-    // Minimal version: rejoin tokens with spaces
-    std::ostringstream oss;
-    for (size_t i = 0; i < tokens.size(); ++i) {
-        if (i > 0) {
-            oss << " ";  // separate tokens by space
-        }
-        oss << tokens[i];
+// Use [[nodiscard]] to ensure return values are handled
+[[nodiscard]] auto createGreeter(std::string_view message) -> Greeter {
+    if (message.empty()) {
+        throw std::invalid_argument("Message cannot be empty");
     }
-    std::string safeCommand = oss.str();
+    return Greeter{message};
+}
 
-    // For demonstration purposes, using system() is still risky.
-    // A truly secure design might replicate or wrap the needed functionality without calling the shell.
-    int result = std::system(safeCommand.c_str());
-    if (result == -1) {
-        std::cerr << "[ERROR] Failed to execute command.\n";
-        return 1;
+} // namespace app
+
+auto main() -> int {
+    try {
+        constexpr std::string_view message = "Hello, World!";
+        auto greeter = app::createGreeter(message);
+        greeter.greet();
+        return EXIT_SUCCESS;
+    } catch (const std::exception& e) {
+        std::cerr << "Error: " << e.what() << '\n';
+        return EXIT_FAILURE;
     }
-
-    std::cout << "[INFO] Command completed with exit code: " << WEXITSTATUS(result) << "\n";
-    return 0;
-}
+}