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[3.8] bpo-36260: Add pitfalls to zipfile module documentation (GH-13378) #15976

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40 changes: 40 additions & 0 deletions Doc/library/zipfile.rst
Original file line number Diff line number Diff line change
Expand Up @@ -816,5 +816,45 @@ Command-line options

Test whether the zipfile is valid or not.

Decompression pitfalls
----------------------

The extraction in zipfile module might fail due to some pitfalls listed below.

From file itself
~~~~~~~~~~~~~~~~

Decompression may fail due to incorrect password / CRC checksum / ZIP format or
unsupported compression method / decryption.

File System limitations
~~~~~~~~~~~~~~~~~~~~~~~

Exceeding limitations on different file systems can cause decompression failed.
Such as allowable characters in the directory entries, length of the file name,
length of the pathname, size of a single file, and number of files, etc.

Resources limitations
~~~~~~~~~~~~~~~~~~~~~

The lack of memory or disk volume would lead to decompression
failed. For example, decompression bombs (aka `ZIP bomb`_)
apply to zipfile library that can cause disk volume exhaustion.

Interruption
~~~~~~~~~~~~

Interruption during the decompression, such as pressing control-C or killing the
decompression process may result in incomplete decompression of the archive.

Default behaviors of extraction
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Not knowing the default extraction behaviors
can cause unexpected decompression results.
For example, when extracting the same archive twice,
it overwrites files without asking.


.. _ZIP bomb: https://en.wikipedia.org/wiki/Zip_bomb
.. _PKZIP Application Note: https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT
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@@ -0,0 +1 @@
Add decompression pitfalls to zipfile module documentation.