1/*
2 * Copyright �� 2020 Alexey Gladkov <gladkov.alexey@gmail.com>
3 *
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15 */
16#include <assert.h>
17#include <unistd.h>
18#include <stdlib.h>
19#include <errno.h>
20#include <linux/mount.h>
21#include <linux/unistd.h>
22
23static inline int fsopen(const char *fsname, unsigned int flags)
24{
25	return syscall(__NR_fsopen, fsname, flags);
26}
27
28static inline int fsconfig(int fd, unsigned int cmd, const char *key, const void *val, int aux)
29{
30	return syscall(__NR_fsconfig, fd, cmd, key, val, aux);
31}
32
33int main(void)
34{
35	int fsfd, ret;
36	int hidepid = 2;
37
38	assert((fsfd = fsopen("proc", 0)) != -1);
39
40	ret = fsconfig(fsfd, FSCONFIG_SET_BINARY, "hidepid", &hidepid, 0);
41	assert(ret == -1);
42	assert(errno == EINVAL);
43
44	assert(!fsconfig(fsfd, FSCONFIG_SET_STRING, "hidepid", "2", 0));
45	assert(!fsconfig(fsfd, FSCONFIG_SET_STRING, "hidepid", "invisible", 0));
46
47	assert(!close(fsfd));
48
49	return 0;
50}
51