xref: /linux/tools/testing/selftests/proc/proc-self-isnt-kthread.c (revision 4b132aacb0768ac1e652cf517097ea6f237214b9)
1 /*
2  * Copyright (c) 2024 Alexey Dobriyan <adobriyan@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 /* Test that userspace program is not kernel thread. */
17 #undef NDEBUG
18 #include <assert.h>
19 #include <fcntl.h>
20 #include <string.h>
21 #include <unistd.h>
22 
23 int main(void)
24 {
25 	int fd = open("/proc/self/status", O_RDONLY);
26 	assert(fd >= 0);
27 
28 	char buf[4096];
29 	ssize_t rv = read(fd, buf, sizeof(buf));
30 	assert(0 <= rv && rv < sizeof(buf));
31 	buf[rv] = '\0';
32 
33 	/* This test is very much not kernel thread. */
34 	assert(strstr(buf, "Kthread:\t0\n"));
35 
36 	return 0;
37 }
38