75 lines
2.0 KiB
Markdown
75 lines
2.0 KiB
Markdown
---
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id: general-03
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original_id: G.UNS.01
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level: G
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impact: MEDIUM
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---
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# Do Not Create Aliases for Types/Methods Named "Unsafe"
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## Summary
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Do not create type aliases, re-exports, or wrapper methods that hide the "unsafe" nature of operations.
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## Rationale
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The word "unsafe" in Rust is a signal to developers that extra scrutiny is required. Hiding this signal makes code review harder and can lead to accidental misuse.
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## Bad Example
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```rust
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// DON'T: Hide unsafe behind an alias
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type SafePointer = *mut u8; // Still unsafe to dereference!
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// DON'T: Wrap unsafe in a "safe-looking" name
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pub fn get_value(ptr: *const i32) -> i32 {
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unsafe { *ptr } // Caller doesn't know this is unsafe!
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}
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// DON'T: Re-export unsafe functions with different names
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pub use std::mem::transmute as convert;
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```
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## Good Example
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```rust
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// DO: Keep "unsafe" visible in the API
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pub unsafe fn get_value_unchecked(ptr: *const i32) -> i32 {
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*ptr
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}
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// DO: If providing a safe wrapper, make the safety contract clear
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/// Returns the value at the pointer.
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///
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/// # Safety
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/// This is safe because the pointer is validated internally.
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pub fn get_value_checked(ptr: *const i32) -> Option<i32> {
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if ptr.is_null() {
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None
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} else {
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// SAFETY: We checked for null above
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Some(unsafe { *ptr })
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}
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}
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// DO: Use clear naming for raw pointer types
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type RawHandle = *mut c_void; // "Raw" signals potential unsafety
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```
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## Common Violations
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1. Creating type aliases that hide pointer types
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2. Wrapping unsafe functions in safe-looking functions without proper safety analysis
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3. Re-exporting unsafe functions with "friendlier" names
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## Checklist
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- [ ] Does my API preserve visibility of unsafe operations?
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- [ ] If wrapping unsafe code in safe API, is the safety invariant enforced?
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- [ ] Are type aliases clearly named to indicate their nature?
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## Related Rules
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- `safety-06`: Don't expose raw pointers in public APIs
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- `safety-09`: Add SAFETY comment before any unsafe block
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