rust-ffilisted

# Rust FFI A boundary that is meant to stay is designed, not discovered. Moving off C — bindgen, cbindgen, and the link into an existing build — is `/port-from-c`. ## The layer only translates Every line of business logic lives in a normal Rust crate that knows nothing about FFI; the `extern` layer converts types, checks pointers, and calls in. The core crate is testable with `cargo test`, the FFI layer only through a foreign harness — logic that drifts into the boundary is logic no test reaches. ```rust use std::ffi::{c_char, CStr}; use std::panic::catch_unwind; // Core: the logic, in code that knows nothing about FFI. pub struct Client { pub name: String, } impl Client { fn new(name: &str) -> Self { Client { name: name.to_owned() } } } // Boundary: translates, checks, and calls in — nothing else. #[repr(transparent)] pub struct MylibClient(*mut Client); /// # Safety /// `name` must be NUL-terminated UTF-8, or null; the check happens once, /// here, on the way in. #[unsafe(no_mangle)] pub unsafe extern "C" fn mylib_client_new(name: *const c_char) -> *mut MylibClient { let build = || { if name.is_null() { return None; } let name = unsafe { CStr::from_ptr(name) }.to_str().ok()?; Some(Box::into_raw(Box::new(Client::new(name))) as *mut MylibClient) }; catch_unwind(build).ok().flatten().unwrap_or(std::ptr::null_mut()) } /// # Safety /// `client` must be a non-null handle from `mylib_client_new`, freed exactly once.