memory-safety-patterns

# Memory Safety Patterns Cross-language patterns for memory-safe programming including RAII, ownership, smart pointers, and resource management. ## When to Use This Skill - Writing memory-safe systems code - Managing resources (files, sockets, memory) - Preventing use-after-free and leaks - Implementing RAII patterns - Choosing between languages for safety - Debugging memory issues ## Core Concepts ### 1. Memory Bug Categories | Bug Type | Description | Prevention | | -------------------- | -------------------------------- | ----------------- | | **Use-after-free** | Access freed memory | Ownership, RAII | | **Double-free** | Free same memory twice | Smart pointers | | **Memory leak** | Never free memory | RAII, GC | | **Buffer overflow** | Write past buffer end | Bounds checking | | **Dangling pointer** | Pointer to freed memory | Lifetime tracking | | **Data race** | Concurrent unsynchronized access | Ownership, Sync | ### 2. Safety Spectrum ``` Manual (C) → Smart Pointers (C++) → Ownership (Rust) → GC (Go, Java) Less safe More safe More control Less control ``` ## Detailed patterns and worked examples Detailed pattern documentation lives in `references/details.md`. Read that file when the navigation tier above is insufficient. ## Best Practices ### Do's - **Prefer RAII** - Tie resource lifetime to scope - **Use smart pointers** - Avoid raw pointers in C++ - **Understand ownership** - Know who owns what - **Check bounds** - Use safe access methods - **Use tools** - AddressSanitizer, Valgrind, Miri ### Don'ts - **Don't use raw pointers** - Unless interfacing with C - **Don't return local references** - Dangling pointer - **Don't ignore compiler warnings** - They catch bugs - **Don't use `unsafe` carelessly** - In Rust, minimize it - **Don't assume thread safety** - Be explicit ## Debugging Tools ```bash # AddressSanitizer (Clang/GCC) clang++ -fsanitize=address -g source.cpp # Valgrind valgrind --leak-check=full ./program # Rust Miri (undefined behavior detector) cargo +nightly miri run # ThreadSanitizer clang++ -fsanitize=thread -g source.cpp ```