sigset.c raw

   1  #include <signal.h>
   2  
   3  void (*sigset(int sig, void (*handler)(int)))(int)
   4  {
   5  	struct sigaction sa, sa_old;
   6  	sigset_t mask, mask_old;
   7  
   8  	sigemptyset(&mask);
   9  	if (sigaddset(&mask, sig) < 0)
  10  		return SIG_ERR;
  11  	
  12  	if (handler == SIG_HOLD) {
  13  		if (sigaction(sig, 0, &sa_old) < 0)
  14  			return SIG_ERR;
  15  		if (sigprocmask(SIG_BLOCK, &mask, &mask_old) < 0)
  16  			return SIG_ERR;
  17  	} else {
  18  		sa.sa_handler = handler;
  19  		sa.sa_flags = 0;
  20  		sigemptyset(&sa.sa_mask);
  21  		if (sigaction(sig, &sa, &sa_old) < 0)
  22  			return SIG_ERR;
  23  		if (sigprocmask(SIG_UNBLOCK, &mask, &mask_old) < 0)
  24  			return SIG_ERR;
  25  	}
  26  	return sigismember(&mask_old, sig) ? SIG_HOLD : sa_old.sa_handler;
  27  }
  28