1 #define _GNU_SOURCE
2 
3 #include <stdio.h>
4 #include <stdlib.h>
5 #include <signal.h>
6 #include <limits.h>
7 #include <unistd.h>
8 #include <errno.h>
9 #include <string.h>
10 #include <fcntl.h>
11 
12 #include <linux/unistd.h>
13 #include <linux/kcmp.h>
14 
15 #include <sys/syscall.h>
16 #include <sys/types.h>
17 #include <sys/stat.h>
18 #include <sys/wait.h>
19 
20 static long sys_kcmp(int pid1, int pid2, int type, int fd1, int fd2)
21 {
22 	return syscall(__NR_kcmp, pid1, pid2, type, fd1, fd2);
23 }
24 
25 int main(int argc, char **argv)
26 {
27 	const char kpath[] = "kcmp-test-file";
28 	int pid1, pid2;
29 	int fd1, fd2;
30 	int status;
31 
32 	fd1 = open(kpath, O_RDWR | O_CREAT | O_TRUNC, 0644);
33 	pid1 = getpid();
34 
35 	if (fd1 < 0) {
36 		perror("Can't create file");
37 		exit(1);
38 	}
39 
40 	pid2 = fork();
41 	if (pid2 < 0) {
42 		perror("fork failed");
43 		exit(1);
44 	}
45 
46 	if (!pid2) {
47 		int pid2 = getpid();
48 		int ret;
49 
50 		fd2 = open(kpath, O_RDWR, 0644);
51 		if (fd2 < 0) {
52 			perror("Can't open file");
53 			exit(1);
54 		}
55 
56 		/* An example of output and arguments */
57 		printf("pid1: %6d pid2: %6d FD: %2ld FILES: %2ld VM: %2ld "
58 		       "FS: %2ld SIGHAND: %2ld IO: %2ld SYSVSEM: %2ld "
59 		       "INV: %2ld\n",
60 		       pid1, pid2,
61 		       sys_kcmp(pid1, pid2, KCMP_FILE,		fd1, fd2),
62 		       sys_kcmp(pid1, pid2, KCMP_FILES,		0, 0),
63 		       sys_kcmp(pid1, pid2, KCMP_VM,		0, 0),
64 		       sys_kcmp(pid1, pid2, KCMP_FS,		0, 0),
65 		       sys_kcmp(pid1, pid2, KCMP_SIGHAND,	0, 0),
66 		       sys_kcmp(pid1, pid2, KCMP_IO,		0, 0),
67 		       sys_kcmp(pid1, pid2, KCMP_SYSVSEM,	0, 0),
68 
69 			/* This one should fail */
70 		       sys_kcmp(pid1, pid2, KCMP_TYPES + 1,	0, 0));
71 
72 		/* This one should return same fd */
73 		ret = sys_kcmp(pid1, pid2, KCMP_FILE, fd1, fd1);
74 		if (ret) {
75 			printf("FAIL: 0 expected but %d returned (%s)\n",
76 				ret, strerror(errno));
77 			ret = -1;
78 		} else
79 			printf("PASS: 0 returned as expected\n");
80 
81 		/* Compare with self */
82 		ret = sys_kcmp(pid1, pid1, KCMP_VM, 0, 0);
83 		if (ret) {
84 			printf("FAIL: 0 expected but %li returned (%s)\n",
85 				ret, strerror(errno));
86 			ret = -1;
87 		} else
88 			printf("PASS: 0 returned as expected\n");
89 
90 		exit(ret);
91 	}
92 
93 	waitpid(pid2, &status, P_ALL);
94 
95 	return 0;
96 }
97