[mod_python] problem with input filter and POST data (fileupload)

Joerg jerch at rockborn.de
Sat Feb 14 17:49:30 EST 2009


I ve encountered a problem with a POST request while a mod_python input filter 
is running (on ubuntu 8.04 with apache 2.2.8 prefork and mod_python 3.3.1).

the situation:
Imagine the simplest input filter as stated in the docs and try to upload a 
file (some big POST data) thru this filter. This file will be trunceated to 
the first 64k.

i have tracked down the problem to fragmented data handling in the file 
util.py. If i change line 363 in that file from
>>> req.readline(readBlockSize)
>>> req.readline()
it works again. so i dumped the stream data here to see wots going on 
with the data with 4 different setups:

1) req.readline() without filter
2) req.readline() with filter
3) req.readline(readBlockSize) without filter
4) req.readline(readBlockSize) with filter

1-3 seem to be exactly the same, while in the 4th case the req-stream is empty 
after some readings (then req.readline(readBlockSize) becomes None and the 
method returns as expected).
I dont know why suddenly the stream is empty long before the boundery (or 
readline() thinks so), could this be some delay effect caused by the filter? 
or is this a special behavior by req.readline() itself with a given length?

If this is not easy to patch, will there be any neg. effect of using 
req.readline() instead of req.readline(readBlockSize) aside from the big file 

Regards, joerg

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