Function libsession_pid_get_owner_uid 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn libsession_pid_get_owner_uid(
    ctx: *mut LibsessionContext,
    pid: pid_t,
    ret_uid: *mut uid_t,
) -> LibsessionStatus

Safety

ctx must be a valid context and ret_uid must point to writable storage.