xref: /linux/tools/testing/selftests/proc/proc-loadavg-001.c (revision ee9294d6ddbd418807ae49f4ab4e6441c9da2a18)
15de3d401SAlexey Dobriyan /*
2*ee9294d6SAlexey Dobriyan  * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
35de3d401SAlexey Dobriyan  *
45de3d401SAlexey Dobriyan  * Permission to use, copy, modify, and distribute this software for any
55de3d401SAlexey Dobriyan  * purpose with or without fee is hereby granted, provided that the above
65de3d401SAlexey Dobriyan  * copyright notice and this permission notice appear in all copies.
75de3d401SAlexey Dobriyan  *
85de3d401SAlexey Dobriyan  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
95de3d401SAlexey Dobriyan  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
105de3d401SAlexey Dobriyan  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
115de3d401SAlexey Dobriyan  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
125de3d401SAlexey Dobriyan  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
135de3d401SAlexey Dobriyan  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
145de3d401SAlexey Dobriyan  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
155de3d401SAlexey Dobriyan  */
165de3d401SAlexey Dobriyan /* Test that /proc/loadavg correctly reports last pid in pid namespace. */
175de3d401SAlexey Dobriyan #define _GNU_SOURCE
185de3d401SAlexey Dobriyan #include <errno.h>
195de3d401SAlexey Dobriyan #include <sched.h>
205de3d401SAlexey Dobriyan #include <sys/types.h>
215de3d401SAlexey Dobriyan #include <sys/stat.h>
225de3d401SAlexey Dobriyan #include <fcntl.h>
235de3d401SAlexey Dobriyan #include <unistd.h>
245de3d401SAlexey Dobriyan #include <sys/wait.h>
255de3d401SAlexey Dobriyan 
265de3d401SAlexey Dobriyan int main(void)
275de3d401SAlexey Dobriyan {
285de3d401SAlexey Dobriyan 	pid_t pid;
295de3d401SAlexey Dobriyan 	int wstatus;
305de3d401SAlexey Dobriyan 
315de3d401SAlexey Dobriyan 	if (unshare(CLONE_NEWPID) == -1) {
325de3d401SAlexey Dobriyan 		if (errno == ENOSYS || errno == EPERM)
335de3d401SAlexey Dobriyan 			return 2;
345de3d401SAlexey Dobriyan 		return 1;
355de3d401SAlexey Dobriyan 	}
365de3d401SAlexey Dobriyan 
375de3d401SAlexey Dobriyan 	pid = fork();
385de3d401SAlexey Dobriyan 	if (pid == -1)
395de3d401SAlexey Dobriyan 		return 1;
405de3d401SAlexey Dobriyan 	if (pid == 0) {
415de3d401SAlexey Dobriyan 		char buf[128], *p;
425de3d401SAlexey Dobriyan 		int fd;
435de3d401SAlexey Dobriyan 		ssize_t rv;
445de3d401SAlexey Dobriyan 
455de3d401SAlexey Dobriyan 		fd = open("/proc/loadavg" , O_RDONLY);
465de3d401SAlexey Dobriyan 		if (fd == -1)
475de3d401SAlexey Dobriyan 			return 1;
485de3d401SAlexey Dobriyan 		rv = read(fd, buf, sizeof(buf));
495de3d401SAlexey Dobriyan 		if (rv < 3)
505de3d401SAlexey Dobriyan 			return 1;
515de3d401SAlexey Dobriyan 		p = buf + rv;
525de3d401SAlexey Dobriyan 
535de3d401SAlexey Dobriyan 		/* pid 1 */
545de3d401SAlexey Dobriyan 		if (!(p[-3] == ' ' && p[-2] == '1' && p[-1] == '\n'))
555de3d401SAlexey Dobriyan 			return 1;
565de3d401SAlexey Dobriyan 
575de3d401SAlexey Dobriyan 		pid = fork();
585de3d401SAlexey Dobriyan 		if (pid == -1)
595de3d401SAlexey Dobriyan 			return 1;
605de3d401SAlexey Dobriyan 		if (pid == 0)
615de3d401SAlexey Dobriyan 			return 0;
625de3d401SAlexey Dobriyan 		if (waitpid(pid, NULL, 0) == -1)
635de3d401SAlexey Dobriyan 			return 1;
645de3d401SAlexey Dobriyan 
655de3d401SAlexey Dobriyan 		lseek(fd, 0, SEEK_SET);
665de3d401SAlexey Dobriyan 		rv = read(fd, buf, sizeof(buf));
675de3d401SAlexey Dobriyan 		if (rv < 3)
685de3d401SAlexey Dobriyan 			return 1;
695de3d401SAlexey Dobriyan 		p = buf + rv;
705de3d401SAlexey Dobriyan 
715de3d401SAlexey Dobriyan 		/* pid 2 */
725de3d401SAlexey Dobriyan 		if (!(p[-3] == ' ' && p[-2] == '2' && p[-1] == '\n'))
735de3d401SAlexey Dobriyan 			return 1;
745de3d401SAlexey Dobriyan 
755de3d401SAlexey Dobriyan 		return 0;
765de3d401SAlexey Dobriyan 	}
775de3d401SAlexey Dobriyan 
785de3d401SAlexey Dobriyan 	if (waitpid(pid, &wstatus, 0) == -1)
795de3d401SAlexey Dobriyan 		return 1;
805de3d401SAlexey Dobriyan 	if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus) == 0)
815de3d401SAlexey Dobriyan 		return 0;
825de3d401SAlexey Dobriyan 	return 1;
835de3d401SAlexey Dobriyan }
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