Title: Inconsistency with uppercase file extensions in MimeTypes.guess_type
Type: behavior Stage: patch review
Components: Library (Lib) Versions: Python 3.11, Python 3.10, Python 3.9
Status: open Resolution:
Dependencies: Superseder:
Assigned To: Nosy List: iritkatriel, kumaraditya303, r.david.murray, rodrigo.parra, tim.golden
Priority: normal Keywords: easy, patch

Created on 2014-01-25 17:17 by rodrigo.parra, last changed 2021-12-22 12:00 by kumaraditya303.

File name Uploaded Description Edit
case_guess_type.patch rodrigo.parra, 2014-01-25 17:17 review
Pull Requests
URL Status Linked Edit
PR 30229 open kumaraditya303, 2021-12-22 12:00
Messages (3)
msg209218 - (view) Author: Rodrigo Parra (rodrigo.parra) Date: 2014-01-25 17:17
The functions looks up for the file extension in three maps: types_map, suffix_map and encodings_map.

Lookup in types_map is case insensitive (by calling lower() first).
Lookup in both suffix_map and encodings_map is case sensitive.

These can lead to some seemingly counterintuitive results, like:

guess_type("foo.tar") == ("application/x-tar", None)
guess_type("foo.TAR") == ("application/x-tar", None)

guess_type("foo.tgz") == ("application/x-tar", "gzip")
guess_type("foo.TGZ") == (None, None)

guess_type("foo.tar.gz") == ("application/x-tar", "gzip")
guess_type("foo.TAR.GZ") == (None, None)

Lookup should be case insensitive at least for the suffix_map, in which case (b) would be solved. The submitted patch implements this change.

As for the encodings_map, I am not so sure, in particular because of the tar.Z extension. I found that the compress command expects the uppercase 'Z'. If someone is relying in the results of guess_type to call compress, errors could occur.
msg209332 - (view) Author: R. David Murray (r.david.murray) * (Python committer) Date: 2014-01-26 15:55
I'm tagging this for 3.5 instead, since there are backward compatibility concerns and the 3.4 RC will probably be a couple weeks from now.
msg408460 - (view) Author: Irit Katriel (iritkatriel) * (Python committer) Date: 2021-12-13 16:08
Reproduced on 3.11.
Date User Action Args
2021-12-22 12:00:39kumaraditya303setkeywords: + patch
nosy: + kumaraditya303

pull_requests: + pull_request28451
stage: patch review
2021-12-13 16:08:59iritkatrielsetversions: + Python 3.9, Python 3.10, Python 3.11, - Python 3.5
nosy: + iritkatriel

messages: + msg408460

keywords: + easy, - patch
2014-01-26 15:55:33r.david.murraysetnosy: + r.david.murray

messages: + msg209332
versions: + Python 3.5, - Python 3.4
2014-01-25 17:17:48rodrigo.parracreate