Function bsearch 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn bsearch(
    key: *const c_void,
    base: *const c_void,
    nel: size_t,
    width: size_t,
    compar: Option<unsafe extern "C" fn(*const c_void, *const c_void) -> c_int>,
) -> *mut c_void

See https://pubs.opengroup.org/onlinepubs/9799919799/functions/bsearch.html.