if (access ("/etc/resolv.conf", R_OK)) { puts ("DNS probably not set up"); return 0; }
main (void){  const char *host = "www.gnu.org";  /* This code approximates the example code in the library manual.  */  struct hostent hostbuf, *hp;  size_t hstbuflen;  char *tmphstbuf;  int res;  int herr;  hstbuflen = 16;		/* Make it way small to ensure ERANGE.  */  /* Allocate buffer, remember to free it to avoid memory leakage.  */  tmphstbuf = malloc (hstbuflen);  while ((res = gethostbyname_r (host, &hostbuf, tmphstbuf, hstbuflen,                                 &hp, &herr)) == ERANGE)    {      /* Enlarge the buffer.  */      hstbuflen *= 2;      tmphstbuf = realloc (tmphstbuf, hstbuflen);    }  if (res != 0 || hp == NULL)    {      printf ("gethostbyname_r failed: %s (errno: %m)\n", strerror (res));      return 1;    }  printf ("Got: %s %s\n", hp->h_name,	  inet_ntoa (*(struct in_addr *) hp->h_addr));  return 0;}