[Linux]关于sigprocmask函数的讨论

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <assert.h>

void printSignal()
{
    sigset_t set;
    int ret = 0;
    sigemptyset(&set);
    ret = sigpending(&set);    
    int i = 1;
    for (i = 1; i < 65; i++)
    {
        if (0 == (ret = sigismember(&set, i)))
        {
            printf("0");
        }
        else if (1 == ret)
        {
            printf("1");
        }
    }
    puts("");
}

void my_sigaction (int num, siginfo_t *st, void *dat)
{
    int ret = 0;
    if (SIGINT == num)
    {
        sigset_t set;
        sigemptyset(&set);
        ret = sigaddset(&set, SIGQUIT);
        assert(-1 != ret);
        ret = sigprocmask(SIG_UNBLOCK, &set, NULL);
        assert(-1 != ret);
        printf("my_sigaction
");
        printSignal();
        printf("func myhandler num = %d
", num);        
    }
    else
    {
        printf("signal is  no SIGQUIT
");
    }
}



int main(void)
{
    int ret = 0;
    
    /* 阻塞信号  */
    sigset_t set;
    sigemptyset(&set);
    ret = sigaddset(&set, SIGQUIT);
    assert(-1 != ret);
    ret = sigprocmask(SIG_BLOCK, &set, NULL);
    assert(-1 != ret);
    printf("阻塞信号
");
    //printSignal();
    sigemptyset(&set);
    /* 
sigpending 是从未决状态字中读取的， 但是未决信号并不能立即得到block的同步
也就是说在block置1时pending并不能够立即的更新为1 
*/
    //sigpending(&set);
    
    /* 注册信号 */
    struct sigaction act;
    act.sa_sigaction = my_sigaction;
    ret = sigemptyset(&(act.sa_mask));
    assert(-1 != ret);
    ret = sigaction(SIGINT, &act, NULL);
    assert(-1 != ret);
    printf("注册信号
");
    printSignal();
    
    while (1)
    {
        printSignal();
        sleep(1);
    }
    return 0;
}