👀 Views: 314 💬 Answers: 1 📅 Created: 2025-06-17

c++17 memory-management smart-pointers C++

I'm working with a null pointer dereference scenario in my C++17 application when using `std::unique_ptr` with a custom deleter. The custom deleter is supposed to release some resources, but sometimes it seems to be called on a null pointer, leading to a crash. Below is a simplified version of my code: ```cpp #include <iostream> #include <memory> struct Resource { Resource() { std::cout << "Resource acquired\n"; } ~Resource() { std::cout << "Resource released\n"; } }; void customDeleter(Resource* res) { if (res) { delete res; } else { std::cout << "Attempted to delete a null resource\n"; } } int main() { std::unique_ptr<Resource, decltype(&customDeleter)> resPtr(new Resource(), customDeleter); resPtr.reset(); // This should invoke the custom deleter resPtr.reset(nullptr); // This line seems to cause issues return 0; } ``` When I run this code, I expect the `customDeleter` to correctly handle the null pointer, but I'm seeing a crash when the second `reset` is called. I've tried changing the order of operations and even adding checks in the deleter, but nothing has resolved the scenario. The behavior message I receive is usually associated with a segmentation fault, which leads me to think I'm somehow mismanaging the ownership of the resource. I've verified that I'm not accidentally trying to access the resource after it's been released. Is there something specific I’m missing in terms of how `std::unique_ptr` manages the custom deleter with subsequent resets? Any help or insights would be greatly appreciated! I'm working in a Debian environment. What are your experiences with this?