#include <liburing.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/resource.h>
#include <unistd.h>

#define DIE(...) do {\
		fprintf(stderr, __VA_ARGS__);\
		abort();\
	} while(0);

static const int RSIZE = 2;
static const int OPEN_FLAGS = O_RDWR | O_CREAT;
static const mode_t OPEN_MODE = S_IRUSR | S_IWUSR;

void open_sync(int dfd, const char* fn)
{
	int fd = openat(dfd, fn, OPEN_FLAGS, OPEN_MODE);
	if (fd < 0) {
		fprintf(stderr, "sync open failed: %s\n", strerror(errno));
	}
	else {
		fprintf(stderr, "sync open succeeded\n");
		close(fd);
	}
}

void open_io_uring(struct io_uring *ring, int dfd, const char* fn)
{
	struct io_uring_sqe *sqe;
	sqe = io_uring_get_sqe(ring);
	if (!sqe) {
		fprintf(stderr, "failed to get sqe\n");
		return;
	}
	io_uring_prep_openat(sqe, dfd, fn, OPEN_FLAGS, OPEN_MODE);
	int ret = io_uring_submit(ring);
	if (ret < 0) {
		fprintf(stderr, "failed to submit openat: %s\n", strerror(-ret));
		return;
	}

	struct io_uring_cqe *cqe;
	ret = io_uring_wait_cqe(ring, &cqe);
	int fd = cqe->res;
	io_uring_cqe_seen(ring, cqe);
	if (ret < 0) {
		fprintf(stderr, "wait_cqe failed: %s\n", strerror(-ret));
	}
	else if (fd < 0) {
		fprintf(stderr, "io_uring openat failed: %s\n", strerror(-fd));
	}
	else {
		fprintf(stderr, "io_uring openat succeeded\n");
		close(fd);
	}
}

int prepare_file(int dfd, const char* fn)
{
	const char buf[] = "foo";
	int fd = openat(dfd, fn, OPEN_FLAGS, OPEN_MODE);
	if (fd < 0) {
		fprintf(stderr, "prepare/open: %s\n", strerror(errno));
		return -1;
	}
	int res = pwrite(fd, buf, sizeof(buf), 1ull << 32);
	if (res < 0) {
		fprintf(stderr, "prepare/pwrite: %s\n", strerror(errno));
	}
	close(fd);
	return res < 0 ? res : 0;
}

int main()
{
	const char *fn = "io_uring_openat_test";
	int dfd = open("/tmp", O_RDONLY | O_DIRECTORY);
	if (dfd < 0) {
		DIE("open /tmp: %s\n", strerror(errno));
	}
	struct io_uring ring;
	int ret = io_uring_queue_init(RSIZE, &ring, 0);
	if (ret < 0) {
		DIE("failed to init io_uring: %s\n", strerror(-ret));
	}

	if (!prepare_file(dfd, fn)) {
		open_sync(dfd, fn);
		open_io_uring(&ring, dfd, fn);
	}

	io_uring_queue_exit(&ring);
	close(dfd);
	return 0;
}