t_sigwaitinfo.c

/**********************************************************************\
*                Copyright (C) Michael Kerrisk, 2010.                  *
*                                                                      *
* This program is free software. You may use, modify, and redistribute *
* it under the terms of the GNU Affero 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 for details.                      *
\**********************************************************************/

/* t_sigwaitinfo.c

   Demonstrate the use of sigwaitinfo() to synchronously wait for a signal.
*/
#define _GNU_SOURCE
#include <string.h>
#include <signal.h>
#include <time.h>
#include "tlpi_hdr.h"

int
main(int argc, char *argv[])
{
    int sig;
    siginfo_t si;
    sigset_t allSigs;

    if (argc > 1 && strcmp(argv[1], "--help") == 0)
        usageErr("%s [delay-secs]\n", argv[0]);

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

    /* Block all signals (except SIGKILL and SIGSTOP) */

    sigfillset(&allSigs);
    if (sigprocmask(SIG_SETMASK, &allSigs, NULL) == -1)
        errExit("sigprocmask");
    printf("%s: signals blocked\n", argv[0]);

    if (argc > 1) {             /* Delay so that signals can be sent to us */
        printf("%s: about to delay %s seconds\n", argv[0], argv[1]);
        sleep(getInt(argv[1], GN_GT_0, "delay-secs"));
        printf("%s: finished delay\n", argv[0]);
    }

    for (;;) {                  /* Fetch signals until SIGINT (^C) or SIGTERM */
        sig = sigwaitinfo(&allSigs, &si);
        if (sig == -1)
            errExit("sigwaitinfo");

        if (sig == SIGINT || sig == SIGTERM)
            exit(EXIT_SUCCESS);

        printf("got signal: %d (%s)\n", sig, strsignal(sig));
        printf("    si_signo=%d, si_code=%d (%s), si_value=%d\n",
                si.si_signo, si.si_code,
                (si.si_code == SI_USER) ? "SI_USER" :
                    (si.si_code == SI_QUEUE) ? "SI_QUEUE" : "other",
                si.si_value.sival_int);
        printf("    si_pid=%ld, si_uid=%ld\n",
                (long) si.si_pid, (long) si.si_uid);
    }
}