#define _GNU_SOURCE
#include <net/if.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <string.h>
#include "syscall.h"

char* if_indextoname(unsigned index, char* name) {
  struct ifreq ifr;
  int fd, r;

  if ((fd = socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0)) < 0)
    return 0;
  ifr.ifr_ifindex = index;
  r = ioctl(fd, SIOCGIFNAME, &ifr);
  __syscall(SYS_close, fd);
  return r < 0 ? 0 : strncpy(name, ifr.ifr_name, IF_NAMESIZE);
}