/* Copyright (c) 2016 Sargun Dhillon <sargun@sargun.me>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of version 2 of the GNU General Public
   * License as published by the Free Software Foundation.
   */
  
  #define _GNU_SOURCE
  #include <stdio.h>
  #include <linux/bpf.h>
  #include <unistd.h>
  #include "libbpf.h"
  #include "bpf_load.h"

  #include <linux/bpf.h>

  #include "cgroup_helpers.h"

  #define CGROUP_PATH		"/my-cgroup"

  
  int main(int argc, char **argv)
  {

  	pid_t remote_pid, local_pid = getpid();

  	int cg2, idx = 0, rc = 0;
  	char filename[256];

  
  	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
  	if (load_bpf_file(filename)) {
  		printf("%s", bpf_log_buf);
  		return 1;
  	}

  	if (setup_cgroup_environment())
  		goto err;

  	cg2 = create_and_get_cgroup(CGROUP_PATH);

  	if (!cg2)
  		goto err;

  	if (bpf_map_update_elem(map_fd[0], &idx, &cg2, BPF_ANY)) {

  		log_err("Adding target cgroup to map");

  		goto err;

  	}

  	if (join_cgroup(CGROUP_PATH))
  		goto err;

  	/*
  	 * The installed helper program catched the sync call, and should
  	 * write it to the map.
  	 */
  
  	sync();

  	bpf_map_lookup_elem(map_fd[1], &idx, &remote_pid);

  
  	if (local_pid != remote_pid) {
  		fprintf(stderr,
  			"BPF Helper didn't write correct PID to map, but: %d
  ",
  			remote_pid);

  		goto err;

  	}
  
  	/* Verify the negative scenario; leave the cgroup */

  	if (join_cgroup("/"))
  		goto err;

  
  	remote_pid = 0;

  	bpf_map_update_elem(map_fd[1], &idx, &remote_pid, BPF_ANY);

  
  	sync();

  	bpf_map_lookup_elem(map_fd[1], &idx, &remote_pid);

  
  	if (local_pid == remote_pid) {
  		fprintf(stderr, "BPF cgroup negative test did not work
  ");

  		goto err;

  	}

  	goto out;
  err:
  	rc = 1;

  out:
  	close(cg2);
  	cleanup_cgroup_environment();
  	return rc;

  }