xact multiple of <tt>CHUNK</tt>, we will miss
the fact that we got to the end-of-file, and not know to tell <tt>deflate()</tt> to finish
up the compressed stream.  If we are not yet at the end of the input, then the <em>zlib</em>
constant <tt>Z_NO_FLUSH</tt> will be passed to <tt>deflate</tt> to indicate that we are still
in the middle of the uncompressed data.
<p>
If there is an error in reading from the input file, the process is aborted with
<tt>deflateEnd()</tt> being called to free the allocated <em>zl