#include <sys/types.h>
#include <sys/wait.h>
#include <err.h>
#include <fcntl.h>
#include <mqueue.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#define MQNAME  "/mytstqueue2"
#define LOOPS   1000
#define PRIO    10

static void
alarmhandler(int sig __unused)
{
        write(1, "timeout\n", 8);
        _exit(1);
}

int
main(void)
{
        struct mq_attr attr;
        mqd_t mq;
        int status;
        pid_t pid;

        mq_unlink(MQNAME);

        attr.mq_maxmsg  = 5;
        attr.mq_msgsize = 128;
        mq = mq_open(MQNAME, O_CREAT | O_RDWR | O_EXCL, 0666, &attr);
        if (mq == (mqd_t)-1)
                err(1, "mq_open");
        status = mq_getattr(mq, &attr);
        if (status)
                err(1, "mq_getattr");
        pid = fork();
        if (pid == 0) { /* child */
                char *buf;
                int j, i;
                unsigned int prio;

                mq_close(mq);

                signal(SIGALRM, alarmhandler);

                mq = mq_open(MQNAME, O_RDWR);
                if (mq == (mqd_t)-1)
                        err(1, "child: mq_open");
                buf = malloc(attr.mq_msgsize);
                for (j = 0; j < LOOPS; ++j) {
                        alarm(3);
                        status = mq_receive(mq, buf, attr.mq_msgsize, &prio);
                        if (status == -1)
                                err(2, "child: mq_receive");
                        for (i = 0; i < attr.mq_msgsize; ++i)
                                if (buf[i] != i)
                                        err(3, "child: message data corrupted");
                        if (prio != PRIO)
                                err(4, "child: priority is incorrect: %d",
                                        prio);
                }
                alarm(0);
                free(buf);
                mq_close(mq);
                return (0);
        } else if (pid == -1) {
                err(1, "fork()");
        } else {
                char *buf;
                int i, j;

                signal(SIGALRM, alarmhandler);
                buf = malloc(attr.mq_msgsize);
                for (j = 0; j < LOOPS; ++j) {
                        for (i = 0; i < attr.mq_msgsize; ++i)
                                buf[i] = i;
                        alarm(3);
                        status = mq_send(mq, buf, attr.mq_msgsize, PRIO);
                        if (status)
                                err(1, "mq_send");
                }
                alarm(3);
                wait(&status);
                alarm(0);
        }
        status = mq_close(mq);
        if (status)
                err(1, "mq_close");
        mq_unlink(MQNAME);
        return (0);
}