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
```

## Patterns by Language

### Pattern 1: RAII in C++

```cpp
// RAII: Resource Acquisition Is Initialization
// Resource lifetime tied to object lifetime

#include <memory>
#include <fstream>
#include <mutex>

// File handle with RAII
class FileHandle {
public:
    explicit FileHandle(const std::string& path)
        : file_(path) {
        if (!file_.is_open()) {
            throw std::runtime_error("Failed to open file");
        }
    }

    // Destructor automatically closes file
    ~FileHandle() = default; // fstream closes in its destructor

    // Delete copy (prevent double-close)
    FileHandle(const FileHandle&) = delete;
    FileHandle& operator=(const FileHandle&) =