#include <sys/types.h>
#include <sys/event.h>
#include <sys/select.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  "/mytstqueue4"
#define LOOPS   1000
#define PRIO    10

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

int
main(void)
{
        struct kevent kev;
        struct mq_attr attr;
        mqd_t mq;
        int kq, 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);
                kq = kqueue();
                mq = mq_open(MQNAME, O_RDWR);
                if (mq == (mqd_t)-1)
                        err(1, "child: mq_open");
                EV_SET(&kev, mq_getfd_np(mq), EVFILT_READ, EV_ADD, 0, 0, 0);
                status = kevent(kq, &kev, 1, NULL, 0, NULL);
                if (status == -1)
                        err(1, "child: kevent");
                buf = malloc(attr.mq_msgsize);
                for (j = 0; j < LOOPS; ++j) {
                        alarm(3);
                        status = kevent(kq, NULL, 0, &kev, 1, NULL);
                        if (status != 1)
                                err(1, "child: kevent 2");
                        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, sighandler);
                kq = kqueue();
                EV_SET(&kev, mq_getfd_np(mq), EVFILT_WRITE, EV_ADD, 0, 0, 0);
                status = kevent(kq, &kev, 1, NULL, 0, NULL);
                if (status == -1)
                        err(1, "kevent");
                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 = kevent(kq, NULL, 0, &kev, 1, NULL);
                        if (status != 1)
                                err(1, "child: kevent 2");
                        status = mq_send(mq, buf, attr.mq_msgsize, PRIO);
                        if (status) {
                                err(2, "mq_send()");
                        }
                }
                free(buf);
                alarm(3);
                wait(&status);
                alarm(0);
        }
        status = mq_close(mq);
        if (status)
                err(1, "mq_close");
        mq_unlink(MQNAME);
        return (0);
}