kcmp_test.c

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#define _GNU_SOURCE

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <limits.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>

#include <linux/unistd.h>
#include <linux/kcmp.h>

#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>

static long sys_kcmp(int pid1, int pid2, int type, int fd1, int fd2)
{
    return syscall(__NR_kcmp, pid1, pid2, type, fd1, fd2);
}

int main(int argc, char **argv)
{
    const char kpath[] = "kcmp-test-file";
    int pid1, pid2;
    int fd1, fd2;
    int status;

    fd1 = open(kpath, O_RDWR | O_CREAT | O_TRUNC, 0644);
    pid1 = getpid();

    if (fd1 < 0) {
        perror("Can't create file");
        exit(1);
    }

    pid2 = fork();
    if (pid2 < 0) {
        perror("fork failed");
        exit(1);
    }

    if (!pid2) {
        int pid2 = getpid();
        int ret;

        fd2 = open(kpath, O_RDWR, 0644);
        if (fd2 < 0) {
            perror("Can't open file");
            exit(1);
        }

        /* An example of output and arguments */
        printf("pid1: %6d pid2: %6d FD: %2ld FILES: %2ld VM: %2ld "
               "FS: %2ld SIGHAND: %2ld IO: %2ld SYSVSEM: %2ld "
               "INV: %2ld\n",
               pid1, pid2,
               sys_kcmp(pid1, pid2, KCMP_FILE,      fd1, fd2),
               sys_kcmp(pid1, pid2, KCMP_FILES,     0, 0),
               sys_kcmp(pid1, pid2, KCMP_VM,        0, 0),
               sys_kcmp(pid1, pid2, KCMP_FS,        0, 0),
               sys_kcmp(pid1, pid2, KCMP_SIGHAND,   0, 0),
               sys_kcmp(pid1, pid2, KCMP_IO,        0, 0),
               sys_kcmp(pid1, pid2, KCMP_SYSVSEM,   0, 0),

            /* This one should fail */
               sys_kcmp(pid1, pid2, KCMP_TYPES + 1, 0, 0));

        /* This one should return same fd */
        ret = sys_kcmp(pid1, pid2, KCMP_FILE, fd1, fd1);
        if (ret) {
            printf("FAIL: 0 expected but %d returned\n", ret);
            ret = -1;
        } else
            printf("PASS: 0 returned as expected\n");

        /* Compare with self */
        ret = sys_kcmp(pid1, pid1, KCMP_VM, 0, 0);
        if (ret) {
            printf("FAIL: 0 expected but %li returned\n", ret);
            ret = -1;
        } else
            printf("PASS: 0 returned as expected\n");

        exit(ret);
    }

    waitpid(pid2, &status, P_ALL);

    return 0;
}