transfer.c

        res = Curl_follow(data, newurl);
        if(CURLE_OK == res) {
          newurl = NULL;
          continue;
        }
      }
    }
    break; /* it only reaches here when this shouldn't loop */

  } while(1); /* loop if Location: */

  if(newurl)
    free(newurl);

  /* run post-transfer uncondionally, but don't clobber the return code if
     we already have an error code recorder */
  res2 = Curl_posttransfer(data);
  if(!res && res2)
    res = res2;

  return res;
}

CURLcode 
Curl_Transfer(struct connectdata *c_conn, /* connection data */
              int sockindex,       /* socket index to read from or -1 */
              curl_off_t size,     /* -1 if unknown at this point */
              bool getheader,      /* TRUE if header parsing is wanted */
              curl_off_t *bytecountp, /* return number of bytes read or NULL */
              int writesockindex,  /* socket index to write to, it may very
                                      well be the same we read from. -1
                                      disables */
              curl_off_t *writecountp /* return number of bytes written or
                                       NULL */
              )
{
  struct connectdata *conn = (struct connectdata *)c_conn;
  if(!conn)
    return CURLE_BAD_FUNCTION_ARGUMENT;

  curlassert((sockindex <= 1) && (sockindex >= -1));

  /* now copy all input parameters */
  conn->sockfd = sockindex==-1?
    CURL_SOCKET_BAD:conn->sock[sockindex];
  conn->size = size;
  conn->bits.getheader = getheader;
  conn->bytecountp = bytecountp;
  conn->writesockfd = writesockindex==-1?
    CURL_SOCKET_BAD:conn->sock[writesockindex];
  conn->writebytecountp = writecountp;

  return CURLE_OK;

}