unsafe-checker

SKILL.md

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⚠️ **Unsafe Rust Checker Loaded**

     *  ^  *
    /◉\_~^~_/◉\
 ⚡/     o     \⚡
   '_        _'
   / '-----' \

Unsafe Rust Checker

When Unsafe is Valid

Use Case Example
FFI Calling C functions
Low-level abstractions Implementing Vec, Arc
Performance Measured bottleneck with safe alternative too slow

NOT valid: Escaping borrow checker without understanding why.

Required Documentation

// SAFETY: <why this is safe>
unsafe { ... }

/// # Safety
/// <caller requirements>
pub unsafe fn dangerous() { ... }

Quick Reference

Operation Safety Requirements
*ptr deref Valid, aligned, initialized
&*ptr + No aliasing violations
transmute Same size, valid bit pattern
extern "C" Correct signature, ABI
static mut Synchronization guaranteed
impl Send/Sync Actually thread-safe

Common Errors

Error Fix
Null pointer deref Check for null before deref
Use after free Ensure lifetime validity
Data race Add proper synchronization
Alignment violation Use #[repr(C)], check alignment
Invalid bit pattern Use MaybeUninit
Missing SAFETY comment Add // SAFETY:

Deprecated → Better

Deprecated Use Instead
mem::uninitialized() MaybeUninit<T>
mem::zeroed() for refs MaybeUninit<T>
Raw pointer arithmetic NonNull<T>, ptr::add
CString::new().unwrap().as_ptr() Store CString first
static mut AtomicT or Mutex
Manual extern bindgen

FFI Crates

Direction Crate
C → Rust bindgen
Rust → C cbindgen
Python PyO3
Node.js napi-rs

Claude knows unsafe Rust. Focus on SAFETY comments and soundness.

Weekly Installs
35
Installed on
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