suspend2.c

UNIX编程高级环境（第二版）的信号部分的程序源码

#include    <signal.h>
#include    "ourhdr.h"

volatile sig_atomic_t    quitflag;    /* set nonzero by signal handler */

int
main(void)
{
    void        sig_int(int);
    sigset_t    newmask, oldmask, zeromask;

    if (signal(SIGINT, sig_int) == SIG_ERR)
        err_sys("signal(SIGINT) error");
    if (signal(SIGQUIT, sig_int) == SIG_ERR)
        err_sys("signal(SIGQUIT) error");

    sigemptyset(&zeromask);

    sigemptyset(&newmask);
    sigaddset(&newmask, SIGQUIT);
                    /* block SIGQUIT and save current signal mask */
    if (sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0)
        err_sys("SIG_BLOCK error");

    while (quitflag == 0)
        sigsuspend(&zeromask);

    /* SIGQUIT has been caught and is now blocked; do whatever */
    quitflag = 0;
                    /* reset signal mask which unblocks SIGQUIT */
    if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)
        err_sys("SIG_SETMASK error");

    exit(0);
}

void
sig_int(int signo)    /* one signal handler for SIGINT and SIGQUIT */
{
    if (signo == SIGINT)
        printf("\ninterrupt\n");
    else if (signo == SIGQUIT)
        quitflag = 1;    /* set flag for main loop */
    return;
}