Function getspnam_r 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn getspnam_r(
    name: *const c_char,
    result_buf: *mut spwd,
    buffer: *mut c_char,
    buflen: size_t,
    result: *mut *mut spwd,
) -> c_int

Non-POSIX, see https://www.man7.org/linux/man-pages/man3/getspnam.3.html.