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classification
Title: email.contentmanager should use IANA encoding
Type: Stage:
Components: email Versions: Python 3.7
process
Status: open Resolution:
Dependencies: Superseder:
Assigned To: Nosy List: barry, era, r.david.murray
Priority: normal Keywords:

Created on 2018-08-22 09:00 by era, last changed 2022-04-11 14:59 by admin.

Messages (2)
msg323869 - (view) Author: (era) Date: 2018-08-22 09:00
https://github.com/python/cpython/blob/3.7/Lib/email/contentmanager.py#L64 currently contains the following code:

    def get_text_content(msg, errors='replace'):
        content = msg.get_payload(decode=True)
        charset = msg.get_param('charset', 'ASCII')
        return content.decode(charset, errors=errors)

This breaks when the IANA character set is not identical to the Python encoding name. For example, pass it a message with

    Content-type: text/plain; charset=cp-850

This breaks for two separate reasons (and I will report two separate bugs); the IANA character-set label should be looked up and converted to a Python codec name (that's this bug) and the character-set alias 'cp-850' is not defined in the lookup table in the place.

There are probably other places in contentmanager.py where a similar mapping should take place. 

I do not have a proper patch, but in general outline, the fix would look like

+    import email.charset
+
     def get_text_content(msg, errors='replace'):
        content = msg.get_payload(decode=True)
        charset = msg.get_param('charset', 'ASCII')
-       return content.decode(charset, errors=errors)
+       encoding = Charset(charset).output_charset()
+       return content.decode(encoding, errors=errors)

This was discovered in this Stack Overflow post: https://stackoverflow.com/a/51961225/874188
msg323871 - (view) Author: (era) Date: 2018-08-22 09:18
https://bugs.python.org/issue34460 now requests the addition of "cp-850" and "windows-784" as charset aliases in the email.charset module.
History
Date User Action Args
2022-04-11 14:59:05adminsetgithub: 78640
2018-08-22 09:18:02erasetmessages: + msg323871
2018-08-22 09:00:20eracreate