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(argv[1]);
46
47	return 0;
48}