/* eBPF example program:
   *
   * - Loads eBPF program
   *
   *   The eBPF program loads a filter from file and attaches the
   *   program to a cgroup using BPF_PROG_ATTACH
   */
  
  #define _GNU_SOURCE
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <stddef.h>
  #include <string.h>
  #include <unistd.h>
  #include <assert.h>
  #include <errno.h>
  #include <fcntl.h>
  #include <net/if.h>
  #include <linux/bpf.h>
  
  #include "libbpf.h"
  #include "bpf_load.h"
  
  static int usage(const char *argv0)
  {
  	printf("Usage: %s cg-path filter-path [filter-id]
  ", argv0);
  	return EXIT_FAILURE;
  }
  
  int main(int argc, char **argv)
  {
  	int cg_fd, ret, filter_id = 0;
  
  	if (argc < 3)
  		return usage(argv[0]);
  
  	cg_fd = open(argv[1], O_DIRECTORY | O_RDONLY);
  	if (cg_fd < 0) {
  		printf("Failed to open cgroup path: '%s'
  ", strerror(errno));
  		return EXIT_FAILURE;
  	}
  
  	if (load_bpf_file(argv[2]))
  		return EXIT_FAILURE;
  
  	printf("Output from kernel verifier:
  %s
  -------
  ", bpf_log_buf);
  
  	if (argc > 3)
  		filter_id = atoi(argv[3]);
  
  	if (filter_id > prog_cnt) {
  		printf("Invalid program id; program not found in file
  ");
  		return EXIT_FAILURE;
  	}
  
  	ret = bpf_prog_attach(prog_fd[filter_id], cg_fd,

  			      BPF_CGROUP_INET_SOCK_CREATE, 0);

  	if (ret < 0) {
  		printf("Failed to attach prog to cgroup: '%s'
  ",
  		       strerror(errno));
  		return EXIT_FAILURE;
  	}
  
  	return EXIT_SUCCESS;
  }