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copied!<p>The <a href="http://www.gzip.org/zlib/rfc-gzip.html#header-trailer" rel="noreferrer">gzip format</a> specifies a field called <code>ISIZE</code> that:</p> <blockquote> <p>This contains the size of the original (uncompressed) input data modulo 2^32.</p> </blockquote> <p>In <a href="http://pydoc.org/get.cgi/usr/local/lib/python2.5/gzip.py" rel="noreferrer">gzip.py</a>, which I assume is what you're using for gzip support, there is a method called <code>_read_eof</code> defined as such:</p> <pre><code>def _read_eof(self): # We've read to the end of the file, so we have to rewind in order # to reread the 8 bytes containing the CRC and the file size. # We check the that the computed CRC and size of the # uncompressed data matches the stored values. Note that the size # stored is the true file size mod 2**32. self.fileobj.seek(-8, 1) crc32 = read32(self.fileobj) isize = U32(read32(self.fileobj)) # may exceed 2GB if U32(crc32) != U32(self.crc): raise IOError, "CRC check failed" elif isize != LOWU32(self.size): raise IOError, "Incorrect length of data produced" </code></pre> <p>There you can see that the <code>ISIZE</code> field is being read, but only to to compare it to <code>self.size</code> for error detection. This then should mean that <code>GzipFile.size</code> stores the actual uncompressed size. However, I <em>think</em> it's not exposed publicly, so you might have to hack it in to expose it. Not so sure, sorry.</p> <p>I just looked all of this up right now, and I haven't tried it so I could be wrong. I hope this is of some use to you. Sorry if I misunderstood your question.</p>

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