Previously, if the read bytes were less than the requested, the
file was closed immediately. This behavior, however, does not
consider the fact that the read operation may be blocking when
no bytes are available at the moment. That is true for a named pipe
(FIFO), for instance. Thus, reading it again lets to the underlying
file system the decision of 1) blocking until bytes become
available or 2) return 0 immediately (the case for actual files) or
3) read available bytes.
