unshare and bind mount namespace

mnt.c

#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <sched.h>
#include <errno.h>
#include <sys/mount.h>
#include <sys/types.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>


int main(int argc, char *argv[])
{
        if (argc < 1) {
                fprintf(stderr, "Need atleast one argument");
                exit(1);
        }

        char path[1024];
        snprintf(path, 1024, "/var/run/ns/%s", argv[1]);
        int ret;
        ret = unshare(CLONE_NEWNS);
        if (ret != 0) {
                perror("unshare");
                exit(1);
        }

        int fd = open(path, O_RDONLY|O_CREAT|O_EXCL, 0);
        if (fd < 0) {
                perror("open");
                exit(1);
        }
        close(fd);

        ret = mount("/proc/self/ns/net", path, "none", MS_BIND, NULL);
        if (ret != 0) {
                perror("mount");
                exit(1);
        }
}