p8-5.c

SUN Solaris8平台下进程间通信

#include <signal.h>
#include <errno.h>
void (*signal(
          int sig,
          void (*handler) (int))) (int)
{
    struct sigaction act, oact;
    /* 检查信号*/
    if (handler == SIG_ERR || sig < 1 || sig >= NSIG){ 
        errno = EINVAL;
        return SIG_ERR;
    }
    act.sa_handler = handler;
    if (sigemptyset (&act.sa_mask) < 0)
        return SIG_ERR;
    act.sa_flags = 0;
    if(sig == SIGALRM){
#ifdef SA_INTERRUPT
        act.sa_flags |= SA_INTERRUPT; /* SunOS 4.x */
#endif
    } else {
# ifdef SA_RESTART
        act.sa_flags |= SA_RESTART;   /* SVR4,4.4BSD */
#endif
    }
    if (sigaction(sig,&act,&oact) < 0)
        return (SIG_ERR);
    return(oact.sa_handler);
}