# Rust Development Guideline

This doc defines some guidelines for developing Teaclave in Rust.

# Style

We use rustfmt and clippy to format and lint all Rust code. Mostly, we use the default configurations, but there are a couple of custom settings and lint exceptions. The exceptions should be defined along with the code. Our CI will check the format/lint issues and deny all warnings by default. Simply run make format to format all code and make CLP=1 to lint code before submitting a PR. If you still have some doubts of the clippy error, feel free to point out and add an exception.

# Elegant APIs

Elegantly designed functions and APIs will make the project readable and user-friendly. Basically, we follow naming conventions and API design patterns of Rust standard library. There's no official guideline, but here are several articles or docs for reference:

# Unsafe Rust

Using unsafe Rust is extremely dangerous, and may break Rust's strong memory-safety guarantees. Therefore, we want to keep unsafe Rust as minimal as possible. Sometime (very rare) using unsafe Rust can significant improve performance, the unsafe code should well documented and explain the rationales. For contributors and reviewers, pay attention to the unsafe code and carefully check whether the pre-conditions and post-conditions are still hold.

# Error Handling

Using unwrap or expect to get a value from an optional type may introduce runtime panic. Therefore, properly using the error handling mechanism provided by Rust can make the system robust and clean. In some cases, optional value can never be None internally, unwrap can be used with a comment explaining the assumptions and reasons. The same rule also applies to panic and similar functions which may cause runtime panic. One exception is to use unwrap and expect in tests, while expect is better because it will show a message to help debugging.

# Third-Party Crates

To ensure the security, stability and compatibility of upstream crates, all third-party crates (especially for ported SGX-compatible crates) used in Teaclave are vendored in the third_party directory. Please refer to the crates-sgx and crates-io repo and choose specific versions of vendored crates.