How to Debug FFI Issues in Rust

Unsafe Ffi

2026-04-17T12:05:42+00:00

Fix Rust FFI errors by matching extern signatures, verifying symbol names, and wrapping calls in unsafe blocks.

Debug FFI issues by verifying extern declarations, ensuring correct unsafe blocks, and checking symbol names for mangling. Use nm or objdump to confirm the C library exports the expected symbols, then wrap the call in unsafe and match the signature exactly.

extern "C" {
    fn c_function_name(arg: i32) -> i32;
}

unsafe {
    let result = c_function_name(42);
}