#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <fcntl.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/syscall.h>
#include <mqueue.h>
#include <sys/stat.h>
#include <assert.h>

#define READERS 10
#define WRITERS 10

static void *read_test(void *data)
{
	char buf[100];
	int fd, good = 0, bad = 0;

	fd = open("/dev/null", O_WRONLY);

        //printf("read test on process : %d thread : %d\n", getpid(), syscall(SYS_gettid));

	while (1) {
		if ((read(fd, buf, sizeof(buf)) != -1) || (errno != EBADF)) {
			int err = errno;
			fprintf(stderr, "%d: (%d/%d) got %d instead of %d\n",
				pthread_self(), bad, bad+good, err, EBADF);
			bad++;
		} else {
			good++;
		}

	}

	return 0;
}

static void *write_test(void *data)
{
	char buf[100];
	int fd, good = 0, bad = 0;

	fd = open("/dev/full", O_WRONLY);

        //printf("write test on process : %d thread : %d\n", getpid(), syscall(SYS_gettid));

	while (1) {
		if ((write(fd, buf, sizeof(buf)) != -1) || (errno != ENOSPC)) {
			int err = errno;
			fprintf(stderr, "%d: (%d/%d) got %d instead of %d\n",
				pthread_self(), bad, bad+good, err, ENOSPC);
			bad++;
		} else {
			good++;

		}
	}

	return 0;
}

static void *overflow_queue(void * data)
{
    mqd_t handle_;

    // Delete any stale queues (ignore any errors)
    mq_unlink("/testqueue");

    struct mq_attr attr = {0};
    attr.mq_maxmsg = 4;
    attr.mq_msgsize = 10;

    handle_ = mq_open("/testqueue", O_RDONLY | O_CREAT, S_IRWXU | S_IRWXG, &attr);

    assert(handle_ != -1);

    handle_ = mq_open("/testqueue", O_WRONLY | O_NONBLOCK);

    assert(handle_ != -1);

    while (1)
    {

    const char* data = "test";
    int size = 4;

    auto volatile errno_prev = errno;

    auto ret = mq_send(handle_, data, size, 0);

    if (ret < 0)
    {
        printf("ret: %d, errno: %d, pre: %d\n", ret, errno, errno_prev);

        if (errno != EAGAIN)
        {
            printf("affending process : %d thread : %d\n", getpid(), syscall(SYS_gettid));
            assert(errno == EAGAIN);
        }

    }

    }
}

int main(void)
{
	pthread_t id;
	int i;

	for (i=0; i<READERS; i++)
		pthread_create(&id, 0, read_test, 0);

	for (i=0; i<(WRITERS-1); i++)
		pthread_create(&id, 0, write_test, 0);


    overflow_queue(0);

	return 0;
}