1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Author: SeongJae Park <sj@kernel.org>
4 */
5
6#include <fcntl.h>
7#include <stdlib.h>
8#include <unistd.h>
9#include <stdio.h>
10
11#pragma GCC diagnostic push
12#if __GNUC__ >= 11 && __GNUC_MINOR__ >= 1
13/* Ignore read(2) overflow and write(2) overread compile warnings */
14#pragma GCC diagnostic ignored "-Wstringop-overread"
15#pragma GCC diagnostic ignored "-Wstringop-overflow"
16#endif
17
18void write_read_with_huge_count(char *file)
19{
20 int filedesc = open(file, O_RDWR);
21 char buf[25];
22 int ret;
23
24 printf("%s %s\n", __func__, file);
25 if (filedesc < 0) {
26 fprintf(stderr, "failed opening %s\n", file);
27 exit(1);
28 }
29
30 write(filedesc, "", 0xfffffffful);
31 perror("after write: ");
32 ret = read(filedesc, buf, 0xfffffffful);
33 perror("after read: ");
34 close(filedesc);
35}
36
37#pragma GCC diagnostic pop
38
39int main(int argc, char *argv[])
40{
41 if (argc != 2) {
42 fprintf(stderr, "Usage: %s <file>\n", argv[0]);
43 exit(1);
44 }
45 write_read_with_huge_count(file: argv[1]);
46
47 return 0;
48}
49

source code of linux/tools/testing/selftests/damon/huge_count_read_write.c