source: example/io/cat.c @ b0904bf

arm-ehenumforall-pointer-decayjacob/cs343-translationnew-ast-unique-expr
Last change on this file since b0904bf was f0d67e5, checked in by Thierry Delisle <tdelisle@…>, 19 months ago

Restored io examples to example folder

  • Property mode set to 100644
File size: 2.0 KB
Line 
1/*
2This is a simple "cat" example that uses io_uring in IORING_SETUP_IOPOLL mode.
3It demonstrates the bare minimum needed to use io_uring in polling mode.
4It uses liburing for simplicity.
5*/
6
7
8#ifndef _GNU_SOURCE
9#define _GNU_SOURCE
10#endif
11
12#include <fcntl.h>
13#include <liburing.h>
14#include <stdio.h>
15#include <string.h>
16#include <unistd.h>
17
18struct io_uring ring;
19
20__attribute__((aligned(1024))) char data[1024];
21
22int main(int argc,  char * argv[]) {
23      if(argc != 2) {
24            printf("usage:   %s FILE - prints file to console.\n", argv[0]);
25            return 1;
26      }
27
28      int fd = open(argv[1], O_DIRECT);
29      if(fd < 0) {
30            printf("Could not open file %s.\n", argv[1]);
31            return 2;
32      }
33
34      /* prep the array */
35      struct iovec iov = { data, 1024 };
36
37      /* init liburing */
38      io_uring_queue_init(256, &ring, IORING_SETUP_IOPOLL);
39
40      /* declare required structs */
41      struct io_uring_sqe * sqe;
42      struct io_uring_cqe * cqe;
43
44      /* get an sqe and fill in a READV operation */
45      sqe = io_uring_get_sqe(&ring);
46      io_uring_prep_readv(sqe, fd, &iov, 1, 0);
47      // io_uring_prep_read(sqe, fd, data, 1024, 0);
48
49      sqe->user_data = (uint64_t)(uintptr_t)data;
50
51      /* tell the kernel we have an sqe ready for consumption */
52      io_uring_submit(&ring);
53
54      /* wait for the sqe to complete */
55      int ret = io_uring_wait_cqe(&ring, &cqe);
56
57      /* read and process cqe event */
58      if(ret == 0) {
59            char * out = (char *)(uintptr_t)cqe->user_data;
60            signed int len = cqe->res;
61            io_uring_cqe_seen(&ring, cqe);
62
63            if(len > 0) {
64                  printf("%.*s", len, out);
65            }
66            else if( len < 0 ) {
67                  fprintf(stderr, "readv/read returned error : %s\n", strerror(-len));
68            }
69      }
70      else {
71            printf("%d\n", ret);
72            io_uring_cqe_seen(&ring, cqe);
73      }
74
75      io_uring_queue_exit(&ring);
76
77      close(fd);
78}
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