signals/t_sigqueue.c

/* t_sigqueue.c

   Demonstrate the use of sigqueue() to send a (realtime) signal.

   Usage: t_sigqueue sig pid data num-sigs

   Send 'num-sigs' instances of the signal 'sig' (specified as an integer), with
   accompanying data 'data' (an integer), to the process with the PID 'pid'.
*/
#define _POSIX_C_SOURCE 199309
#include <signal.h>
#include "tlpi_hdr.h"

int
main(int argc, char *argv[])
{
    int sig, numSigs, j, sigData;
    union sigval sv;

    if (argc < 4 || strcmp(argv[1], "--help") == 0)
        usageErr("%s pid sig-num data [num-sigs]\n", argv[0]);

    /* Display our PID and UID, so that they can be compared with the
       corresponding fields of the siginfo_t argument supplied to the
       handler in the receiving process */

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

    sig = getInt(argv[2], 0, "sig-num");
    sigData = getInt(argv[3], GN_ANY_BASE, "data");
    numSigs = (argc > 4) ? getInt(argv[4], GN_GT_0, "num-sigs") : 1;

    for (j = 0; j < numSigs; j++) {
        sv.sival_int = sigData + j;
        if (sigqueue(getLong(argv[1], 0, "pid"), sig, sv) == -1)
            errExit("sigqueue %d", j);
    }

    exit(EXIT_SUCCESS);
}