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 
18 void 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 
39 int 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 }
49