Linux_unix系统编程手册以同步方式等待信号

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/andrewgithub/article/details/84996133

使用信号处理器和sigsuspend()来挂起一个进程的执行，直至传来一个信号

通过文件描述符来获取信号

/*************************************************************************\
*                  Copyright (C) Michael Kerrisk, 2018.                   *
*                                                                         *
* This program is free software. You may use, modify, and redistribute it *
* under the terms of the GNU General Public License as published by the   *
* Free Software Foundation, either version 3 or (at your option) any      *
* later version. This program is distributed without any warranty.  See   *
* the file COPYING.gpl-v3 for details.                                    *
\*************************************************************************/

/* Listing 22-7 */

/* signalfd_sigval.c

   Usage: signalfd_sigval sig-num...

   Demonstrate the use of signalfd() to receive signals via a file descriptor.

   This program is Linux-specific. The signalfd API is supported since kernel
   2.6.22.
*/
#include <sys/signalfd.h>
#include <signal.h>
#include "tlpi_hdr.h"

int
main(int argc, char *argv[])
{
    sigset_t mask;
    int sfd, j;
    struct signalfd_siginfo fdsi;
    ssize_t s;

    if (argc < 2 || strcmp(argv[1], "--help") == 0)
        usageErr("%s sig-num...\n", argv[0]);

    printf("%s: PID = %ld\n", argv[0], (long) getpid());

    sigemptyset(&mask);
    for (j = 1; j < argc; j++)
        sigaddset(&mask, atoi(argv[j]));

    if (sigprocmask(SIG_BLOCK, &mask, NULL) == -1)
        errExit("sigprocmask");

    sfd = signalfd(-1, &mask, 0);
    if (sfd == -1)
        errExit("signalfd");

    for (;;) {
        s = read(sfd, &fdsi, sizeof(struct signalfd_siginfo));
        if (s != sizeof(struct signalfd_siginfo))
            errExit("read");

        printf("%s: got signal %d", argv[0], fdsi.ssi_signo);
        if (fdsi.ssi_code == SI_QUEUE) {
            printf("; ssi_pid = %d; ", fdsi.ssi_pid);
            printf("ssi_int = %d", fdsi.ssi_int);
        }
        printf("\n");
    }
}