suspend1.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"

static void    sig_int(int);

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

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

    sigemptyset(&zeromask);

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

                    /* critical region of code */
    pr_mask("in critical region: ");

                    /* allow all signals and pause */
    if (sigsuspend(&zeromask) != -1)
        err_sys("sigsuspend error");
    pr_mask("after return from sigsuspend: ");

                    /* reset signal mask which unblocks SIGINT */
    if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0)
        err_sys("SIG_SETMASK error");

                    /* and continue processing ... */
    exit(0);
}

static void
sig_int(int signo)
{
    pr_mask("\nin sig_int: ");
    return;
}