signal_handler_t sys_signal (int signal_number, signal_handler_t action);
sigset_t sys_sigblock (sigset_t new_mask);
sigset_t sys_sigunblock (sigset_t new_mask);
sigset_t sys_sigsetmask (sigset_t new_mask);
signal_handler_t sys_signal (int signal_number, signal_handler_t action);
sigset_t sys_sigblock (sigset_t new_mask);
sigset_t sys_sigunblock (sigset_t new_mask);
sigset_t sys_sigsetmask (sigset_t new_mask);