/unsafe-check

/unsafe-check

Check a file for unsafe code issues and potential safety violations.

Usage

/unsafe-check [file]

Parameters

• `file` (optional): Path to the Rust file to check. If not provided, checks the current file or prompts for input.

Workflow

1. **Read the file** to identify all `unsafe` blocks and `unsafe fn` 2. **Load unsafe-checker skill** rules 3. **Check each unsafe block** against relevant rules:

• SAFETY comment present? (safety-09)
• Pointer validity verified? (ptr-*)
• Panic safety considered? (safety-01)
• FFI rules followed? (ffi-*)

4. **Report findings** with rule references and fix suggestions

Checks Performed

Safety Comments

• Every `unsafe` block should have `// SAFETY:` comment
• Comment should explain invariants, not just say "this is safe"

Pointer Operations

• Null checks before dereference
• Alignment verification
• Bounds checking
• No aliasing violations

FFI

• Types have `#[repr(C)]`
• Panics caught at boundary
• String handling correct
• Memory ownership clear

Send/Sync

• Manual implementations are sound
• No data races possible

Example Output

Checking: src/lib.rs

Found 3 unsafe blocks:

1. Line 42: unsafe { ptr.read() }
   - [WARN] Missing SAFETY comment (safety-09)
   - [WARN] No null check for ptr (ptr-01)
   Suggestion: Add SAFETY comment and verify ptr is non-null

2. Line 87: unsafe impl Send for MyType {}
   - [WARN] Missing Safety docs (safety-10)
   - [OK] Type analysis shows no !Send fields
   Suggestion: Add /// # Safety documentation

3. Line 123: extern "C" fn callback() { ... }
   - [WARN] No catch_unwind (ffi-04)
   Suggestion: Wrap body in std::panic::catch_unwind

Related Commands

• `/unsafe-review` - Interactive unsafe code review
• `/guideline` - Query specific rules