On 21/05/2020 14:50, Steve Barnes wrote:
The issue is simple and simple enough for a beginner to fall foul of - test
procedure:
Change directory to any directory with files in totally a few 10s of megs
(ideally but it doesn't matter much).
python -m zipfile -c my_zipfile.zip .
Wait a few minutes and press control-C then do a directory - you will find that
my_zipfile.zip is huge (much bigger than the total of the files in the original
directory). The same applies to tarfile.
If you fail to hit control-C soon enough (how long depends on the spare space
on the current drive) it will crash when it runs out of disk space, possibly,
on some systems, requiring a format and re-install of the OS.
The cause of the problem is that when zipfile &/or tarfile is archiving to a
file in the current directory it tries to add the target file to the input list and
you have an Ouroboros situation. The fix is also simple - exclude the target file
from the permitted inputs.
Am I missing something here?
IIUC zipfile.py tries to add the zipfile it's creating to the zipfile
it's creating.
That's a bug, pure and simple (and a dangerous one).
It should be rewritten to build a list of the files it's going to zip up
(before creating its own zipfile), then work from that list.
Surely it can't be that hard?
I have seen this happen in the wild, I do know that python is not the only
archiving tool that suffers from this problem but that seems to me to be no
reason not to address this.
If write were patched to simply count the bytes but not write the file then the
problem would not occur so I guess that it would need to be patched in a
transparent manner.
Steve Barnes
-----Original Message-----
From: remi.lape...@henki.fr <remi.lape...@henki.fr>
Sent: 21 May 2020 13:56
To: python-ideas@python.org
Subject: [Python-ideas] Re: How to propose a change with tests where the
failing test case (current behaviour) is bad or dangerous
If the file is supposed to be small, would patching write() in the test to
accumulate the number of bytes written and fail the test when it goes over what
it's supposed to be possible?
What is the issue?
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