[Zlib-devel] Negative argument wsize in "inflateInit2()"

[Jesus Cea]

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I am studying a zlib related crash in Python code, when using to
zipimporter.

Tracking down the issue, I see this, in python "zipimport.c":

"""
data = PyObject_CallFunction(decompress, "Oi", raw_data, -15);
"""

This function will call "inflateInit2()" with the "-15" value for wsize.
Reading python docs, I see this:
http://docs.python.org/library/zlib.html#zlib.decompress . The scary
thing is the "undocumented" feature. I guess it was dropped in current
zlib library.

If I change the value to "15", I can not import zipped python modules
anymore. The importer needs more love to be able to work as before, with
wsize=15.

I would like to know if passing "-15" to zlib is still supported (but
undocumented) and I must keep investigating the problem, or that
functionality was eliminates in zlib 1.2.5 and I have to patch python (I
am a python core developer, so this is actually a posibility) to change
- -15 by 15 and estore the zipimport capability.

In the latter case I would like to know what I can do to be able to
decompress zip files again :). Maybe it is enough to skip some initial
bytes in the stream, maybe I have to generate a "fake" gzip header
internally... Any idea?.

Thanks for your time and attention.

- -- 
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