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cgi.parse_multipart() requires undocumented CONTENT-LENGTH in Python 3.7 #78407

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yan12125 mannequin opened this issue Jul 25, 2018 · 11 comments
Closed

cgi.parse_multipart() requires undocumented CONTENT-LENGTH in Python 3.7 #78407

yan12125 mannequin opened this issue Jul 25, 2018 · 11 comments
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@orsenthil
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3.7 (EOL) end of life 3.8 only security fixes 3.9 only security fixes 3.10 only security fixes docs Documentation in the Doc dir stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error

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@yan12125
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yan12125 mannequin commented Jul 25, 2018

BPO 34226
Nosy @freddrake, @orsenthil, @ned-deily, @PierreQuentel, @vadmium, @yan12125, @miss-islington, @tirkarthi, @Roger, @0x3333, @YtvwlD
PRs
  • bpo-34226: fix cgi.parse_multipart without content_length #8530
  • [3.9] bpo-34226: fix cgi.parse_multipart without content_length (GH-8530) #20890
  • [3.8] bpo-34226: fix cgi.parse_multipart without content_length (GH-8530) #20891
  • [3.7] bpo-34226: fix cgi.parse_multipart without content_length (GH-8530) #20892
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    Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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    GitHub fields:

    assignee = 'https://github.com/orsenthil'
closed_at = <Date 2020-06-15.16:04:52.499>
created_at = <Date 2018-07-25.14:55:40.577>
labels = ['type-bug', '3.8', '3.9', '3.10', '3.7', 'library', 'docs']
title = 'cgi.parse_multipart() requires undocumented CONTENT-LENGTH in Python 3.7'
updated_at = <Date 2020-06-15.17:59:28.374>
user = 'https://github.com/yan12125'

    bugs.python.org fields:

    activity = <Date 2020-06-15.17:59:28.374>
actor = 'orsenthil'
assignee = 'orsenthil'
closed = True
closed_date = <Date 2020-06-15.16:04:52.499>
closer = 'orsenthil'
components = ['Documentation', 'Library (Lib)']
creation = <Date 2018-07-25.14:55:40.577>
creator = 'yan12125'
dependencies = []
files = []
hgrepos = []
issue_num = 34226
keywords = ['patch', '3.7regression']
message_count = 11.0
messages = ['322362', '322541', '353545', '371340', '371350', '371367', '371557', '371563', '371565', '371566', '371583']
nosy_count = 12.0
nosy_names = ['fdrake', 'orsenthil', 'ned.deily', 'docs@python', 'quentel', 'martin.panter', 'yan12125', 'miss-islington', 'xtreak', 'rogerduran', 'Tercio Gaudencio Filho', 'ytvwld']
pr_nums = ['8530', '20890', '20891', '20892']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue34226'
versions = ['Python 3.7', 'Python 3.8', 'Python 3.9', 'Python 3.10']
    @yan12125
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    yan12125 mannequin commented Jul 25, 2018

    In Python 3.7, cgi.parse_multipart() requires "CONTENT-LENGTH" in the second parameter pdict. This is not necesary in Python 3.6.

    For example, the following code runs with 3.6:

    $ python3.6
Python 3.6.6 (default, Jun 27 2018, 13:11:40) 
[GCC 8.1.1 20180531] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import cgi, io
>>> data = b'--heyDavid\r\nContent-Disposition: form-data; name="cfield"\r\n\r\njust a string\r\n\r\n--heyDavid--\r\n'
>>> cgi.parse_multipart(io.BytesIO(data), {"boundary": b"heyDavid"})
{'cfield': [b'just a string\r\n']}

    While not on 3.7:

    $ python3.7
Python 3.7.0 (default, Jul 15 2018, 10:44:58) 
[GCC 8.1.1 20180531] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import cgi, io
>>> data = b'--heyDavid\r\nContent-Disposition: form-data; name="cfield"\r\n\r\njust a string\r\n\r\n--heyDavid--\r\n'
>>> cgi.parse_multipart(io.BytesIO(data), {"boundary": b"heyDavid"})
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.7/cgi.py", line 220, in parse_multipart
    headers['Content-Length'] = pdict['CONTENT-LENGTH']
KeyError: 'CONTENT-LENGTH'

    I looked into the source code of CPython, and found CONTENT-LENGTH in nowhere but cgi.py and test_cgi.py. I guess it has the same meaning as the Content-Length header in HTTP or CONTENT_LENGTH environment variable in CGI? It would be great to document such a backward-incompatible behavior.

    Environment: Arch Linux with Python 3.6.6 from [extra] repo and 3.7.0 from [staging] repo.

    CC the author and the reviewer of bpo-29979, where relevant codes are introduced.

    @yan12125 yan12125 mannequin assigned docspython Jul 25, 2018
    @yan12125 yan12125 mannequin added 3.7 (EOL) end of life 3.8 only security fixes docs Documentation in the Doc dir stdlib Python modules in the Lib dir type-bug An unexpected behavior, bug, or error labels Jul 25, 2018
    @Roger
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    Roger mannequin commented Jul 28, 2018

    working on this on europython

    @vadmium
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    vadmium commented Sep 30, 2019

    Looks like the change causing this is revision cc3fa20. I would remove the reference to pdict['CONTENT-LENGTH'].

    @ned-deily
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    I note this is marked as a 3.7regression and still open. Since the cutoff for the final 3.7 bugfix mode release is in a few days, I'm assuming this means that 3.7 users will have to live with this regression. If you feel that is a problem, speak up now.

    @YtvwlD
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    YtvwlD mannequin commented Jun 12, 2020

    Since there's the easy workaround of just setting pdict["CONTENT-LENGTH"] I personally don't have a problem with this staying the way it is.

    But it would be really nice if this were documented somewhere.

    @orsenthil
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    I will spend time on this on 12-June or 13-June, 2020.
    At the very least, if no changes are required, I will document this for 3.7 and higher versions.

    @orsenthil orsenthil assigned orsenthil and unassigned docspython Jun 12, 2020
    @miss-islington
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    New changeset d8cf351 by roger in branch 'master':
    bpo-34226: fix cgi.parse_multipart without content_length (GH-8530)
    d8cf351

    @miss-islington
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    New changeset aa83935 by Miss Islington (bot) in branch '3.7':
    [3.7] bpo-34226: fix cgi.parse_multipart without content_length (GH-8530) (GH-20892)
    aa83935

    @miss-islington
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    New changeset b87453f by Miss Islington (bot) in branch '3.9':
    bpo-34226: fix cgi.parse_multipart without content_length (GH-8530)
    b87453f

    @miss-islington
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    New changeset c72b7f7 by Miss Islington (bot) in branch '3.8':
    bpo-34226: fix cgi.parse_multipart without content_length (GH-8530)
    c72b7f7

    @orsenthil orsenthil added 3.9 only security fixes 3.10 only security fixes labels Jun 15, 2020
    @orsenthil
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    This is now fixed in all active versions of python. No documentation changes required for this change.

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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