sig_current
sig_t volatile oldsigpipe = sig_current(SIGPIPE);
sig_t volatile old_sigint = sig_current(SIGINT);
sig_t volatile old_sighup = sig_current(SIGHUP);
sig_t volatile old_sigtstp = sig_current(SIGTSTP);
sig_t volatile old_sigttin = sig_current(SIGTTIN);
sig_t volatile old_sigttou = sig_current(SIGTTOU);
sig_t sig_current(int);