#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <mqueue.h>
#include <signal.h>
#include <stdio.h>

#define MQNAME  "/mytstqueue1"

int
main(void)
{
        struct mq_attr attr, attr2;
        struct sigevent sigev;
        mqd_t mq;
        int status;

        attr.mq_maxmsg  = 2;
        attr.mq_msgsize = 100;
        mq = mq_open(MQNAME, O_CREAT | O_RDWR | O_EXCL, 0666, &attr);
        if (mq == (mqd_t)-1)
                err(1, "mq_open");
        status = mq_unlink(MQNAME);
        if (status)
                err(1, "mq_unlink");
        status = mq_getattr(mq, &attr2);
        if (status)
                err(1, "mq_getattr");
        if (attr.mq_maxmsg != attr2.mq_maxmsg)
                err(1, "mq_maxmsg changed");
        if (attr.mq_msgsize != attr2.mq_msgsize)
                err(1, "mq_msgsize changed");

        sigev.sigev_notify = SIGEV_SIGNAL;
        sigev.sigev_signo = SIGRTMIN;
        status = mq_notify(mq, &sigev);
        if (status)
                err(1, "mq_notify");
        status = mq_notify(mq, &sigev);
        if (status == 0)
                err(1, "mq_notify 2");
        else if (errno != EBUSY)
                err(1, "mq_notify 3");
        status = mq_notify(mq, NULL);
        if (status)
                err(1, "mq_notify 4");
        status = mq_close(mq);
        if (status)
                err(1, "mq_close");
        return (0);
}