sq_poll_accept.c

#include <errno.h>
#include <fcntl.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <sys/socket.h>
#include <unistd.h>
#include <poll.h>
#include <assert.h>
#include "liburing.h"
#include <assert.h>

#define BACKLOG 512

#define PORT 9700

#define SQ_POLL 1

struct io_uring ring;

int setup_io_uring() {
    struct io_uring_params p;
	int ret;

	memset(&p, 0, sizeof(p));

	if (SQ_POLL) {
		p.flags = IORING_SETUP_SQPOLL;
	}
    ret = io_uring_queue_init_params(16, &ring, &p);
    if (ret) {
        fprintf(stderr, "Unable to setup io_uring: %s\n", strerror(-ret));
        return 1;
    }
    return 0;
}

void add_poll(int fd, unsigned int poll_mask) {
    struct io_uring_sqe *sqe = io_uring_get_sqe(&ring);
    io_uring_prep_poll_add(sqe, fd, poll_mask);

    if (SQ_POLL) {
		sqe->flags = IOSQE_FIXED_FILE;
	}
    sqe->user_data = 11;
}

void add_accept(int fd) {
    struct io_uring_sqe *sqe = io_uring_get_sqe(&ring);
    io_uring_prep_accept(sqe, fd, 0, 0, SOCK_NONBLOCK | SOCK_CLOEXEC);
    if (SQ_POLL) {
		sqe->flags = IOSQE_FIXED_FILE;
	}
    sqe->user_data = 22;
}

int create_server_socket(struct sockaddr_in serv_addr) {
    int sock_listen_fd = socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK, 0);
    const int val = 1;
    setsockopt(sock_listen_fd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));

    if (bind(sock_listen_fd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
         perror("Error binding socket\n");
         exit(1);
     }
    if (listen(sock_listen_fd, BACKLOG) < 0) {
         perror("Error listening on socket\n");
         exit(1);
    }
    return sock_listen_fd;
}

int main(int argc, char *argv[]) {
    setup_io_uring();
    int sock;
    
    struct sockaddr_in serv_addr;
    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(PORT);
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    
    int sock_listen_fd = create_server_socket(serv_addr);

    int *fds = malloc(10 * sizeof(int));
    
    fds[0] = sock_listen_fd;

    if(SQ_POLL) {
        printf("register files: %d \n", io_uring_register_files(&ring, fds, 10));
    }

    if(SQ_POLL) {
        sock = 0; //register file index
    } else {
        sock = sock_listen_fd;
    }

    add_poll(sock, POLLIN);
    io_uring_submit(&ring);
    
    struct io_uring_cqe *cqe;
    io_uring_wait_cqe(&ring, &cqe);
    

    assert(cqe->user_data == 11);
    assert(cqe->res > 0);
    io_uring_cqe_seen(&ring, cqe);

    add_accept(sock);
    io_uring_submit(&ring);

    io_uring_wait_cqe(&ring, &cqe);
    assert(cqe->user_data == 22);

    //it seems to fail with -EINVAL
    printf("cqe->res: %d \n", cqe->res);
    assert(cqe->res > 0);

    sleep(8);

    io_uring_queue_exit(&ring);
    return 0;
}