signal 함수

 

http://revoman.tistory.com/entry/signal-함수-구현

 

출처 :Advanced Programming in the UNIX® Environment: Second Edition

 

1.typedef void   Sigfunc(int);   /* for signal handlers */

static Sigfunc *_Signal(int signo, Sigfunc *func);
static Sigfunc *_Signal_Intr(int signo, Sigfunc *func);

/*
* Reliable version of signal(), using POSIX sigaction().
*/

static Sigfunc *_Signal(int signo, Sigfunc *func)
{
  struct sigaction    act, oact;

  act.sa_handler = func;
  sigemptyset(&act.sa_mask);
  act.sa_flags = 0;
  if (signo == SIGALRM) {
#ifdef SA_INTERRUPT
      act.sa_flags |= SA_INTERRUPT;
#endif
  } else {
#ifdef  SA_RESTART
      act.sa_flags |= SA_RESTART;
#endif
  }
  if (sigaction(signo, &act, &oact) < 0)
      return(SIG_ERR);
  return(oact.sa_handler);
}

/*
* a version of the signal function that tries to
* prevent any interrupted system calls from being restarted.
*/
static Sigfunc *_Signal_Intr(int signo, Sigfunc *func)
{
  struct sigaction    act, oact;

  act.sa_handler = func;
  sigemptyset(&act.sa_mask);
  act.sa_flags = 0;
#ifdef  SA_INTERRUPT
  act.sa_flags |= SA_INTERRUPT;
#endif
  if (sigaction(signo, &act, &oact) < 0)
      return(SIG_ERR);
  return(oact.sa_handler);
}