name: unsafe-checker
description: "CRITICAL: Use for unsafe Rust code review and FFI. Triggers on: unsafe, raw pointer, FFI, extern, transmute, *mut, const, union, #[repr(C)], libc, std::ffi, MaybeUninit, NonNull, SAFETY comment, soundness, undefined behavior, UB, safe wrapper, memory layout, bindgen, cbindgen, CString, CStr, 安全抽象, 裸指针, 外部函数接口, 内存布局, 不安全代码, FFI 绑定, 未定义行为"
globs: ["**/.rs"]
allowed-tools: ["Read", "Grep", "Glob"]
Display the following ASCII art exactly as shown. Do not modify spaces or line breaks:
⚠️ **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.
By