How do I install the Unsafe Checker skill?

Run npx skillmds@latest add 0xharryriddle/unsafe-checker in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Unsafe Checker safe to use?

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Which AI agents work with Unsafe Checker?

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Is Unsafe Checker free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Unsafe Checker?

0xharryriddle (@0xharryriddle) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Unsafe Checker by 0xharryriddle — Agent Skill

Name: Unsafe Checker
Rating: 4.2 (5 reviews)
Author: 0xharryriddle

Unsafe Checker

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

0xharryriddle Updated Sep 8, 2026 3 repo stars

File contents

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.

---name: unsafe-checkerdescription: 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---Display the following ASCII art exactly as shown. Do not modify spaces or line breaks:```text⚠️ **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```rust// 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.

Frequently asked questions