Python zlib not decodable when returned by an http response

Question

I'm using Amazon S3 to serve static files. When the Content-Type is just 'text/css' and I haven't compressed the file, it is returned ok. If I try to zlib.compress() the contents that will be returned and change Content-Encoding to 'gzip', the browser cannot decode the result. In Chrome, the error is

Error 330 net::ERR_CONTENT_DECODING_FAILED

in Safari,

“cannot decode raw data” (NSURLErrorDomain:-1015)

Is there something special to do with python's zlib to make sure the result can be returned and decompressed by the browser?

Here's how to do with with the zlib library: http://stackoverflow.com/questions/2695152/in-python-how-do-i-decode-gzip-encoding — Ric, Mar 06 '15 at 02:47

score 5 · Answer 1 · answered Apr 26 '10 at 14:58

5

I have this same problem.

If you send the header:

Content-Encoding: gzip

Safari/Chrome show that error.

But if you instead send:

Content-Encoding: deflate

Safari/Chrome decodes the input fine.

answered Apr 26 '10 at 14:58

Jonathan Works

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Thanks! This was driving me shnutz. – charleslparker Nov 20 '13 at 19:39

score 2 · Answer 2 · answered Dec 02 '09 at 20:34

2

gzip is not the same as zlib.

answered Dec 02 '09 at 20:34

Mark Byers

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score 0 · Answer 3 · answered Jan 15 '13 at 17:07

Instead of using the module zlib, (originalString = inputFile.read() and then compressedString = zlib.compress(originalString)) I am now using the module gzip:

stream = cStringIO.StringIO()
compressor = gzip.GzipFile(fileobj=stream, mode='w')
while True:  # until EOF
    chunk = inputFile.read(8192)
    if not chunk:  # EOF?
        compressor.close()
        return stream.getvalue()
    compressor.write(chunk)

The result then is compatible to gzip; I don't know if it fixes your webserver issue as well.

score 0 · Answer 4 · answered Dec 02 '09 at 22:43

0

It is decodable. The problem is that the sender is lying to the receiver -- not a good way of ensuring harmonious communication. Try calling it "zlib" instead of "gzip".

answered Dec 02 '09 at 22:43

John Machin

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Python zlib not decodable when returned by an http response

4 Answers4