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Title: HTMLParser silently stops parsing with malformed attributes
Type: behavior Stage: resolved
Components: Library (Lib) Versions: Python 3.2, Python 3.3, Python 2.7
Status: closed Resolution: fixed
Dependencies: Superseder:
Assigned To: ezio.melotti Nosy List: eric.araujo, ezio.melotti, python-dev, r.david.murray, teoryn
Priority: normal Keywords: patch

Created on 2011-07-24 18:35 by teoryn, last changed 2022-04-11 14:57 by admin. This issue is now closed.

File name Uploaded Description Edit teoryn, 2011-07-24 18:35 Example of the broken behavior
issue12629.diff ezio.melotti, 2011-11-01 13:21 Failing test review
Messages (8)
msg141051 - (view) Author: Kevin Stock (teoryn) Date: 2011-07-24 18:35
Given the input '<x><y z=""o"" /></x>', HTMLParser only detects the opening x tag, and then stops parsing. Ideally this should behave like the case '<x><y z="""" /></x>' which raises an error and then can continue parsing the close x tag.
msg141174 - (view) Author: Kevin Stock (teoryn) Date: 2011-07-26 18:07
A workaround is to call close() after feed(), which I supposed I should have done anyways. However, this does not resolve the issue that the two cases behave so differently. 

The code that causes the difference is lines 351-355 of, which also has a misleading comment stating it detects the / in a /> ending (which is actually done at 334).
msg146774 - (view) Author: Ezio Melotti (ezio.melotti) * (Python committer) Date: 2011-11-01 13:21
I think <x><y z=""o"" /></x> should be parser as <x><y z="" /></x>, and the o"" should be ignored.
<x><y z="""" /></x> should be parser as <x><y z="" /></x>, and the last two "" should be ignored.  This is what Firefox seems to do.

Currently the parser doesn't seem to handle extraneous data in the start tag too well, because the locatestarttagend_tolerant regex looks for (more or less) well-formed attributes.
Attached a patch for test_htmlparser with the two examples provided by Kevin.
msg146848 - (view) Author: Éric Araujo (eric.araujo) * (Python committer) Date: 2011-11-02 16:53
> This is what Firefox seems to do.
I think more confidence would be good.  Doesn’t the HTML5 spec define that?  Have you found their test suite?  Do you have more than one browser known to be compliant (trick: not sure there is even one)?
msg146852 - (view) Author: Ezio Melotti (ezio.melotti) * (Python committer) Date: 2011-11-02 17:08
I haven't found anything in the HTML5 spec but I haven't looked closely.
I'll do some more research when I'll start working on an actual patch.
msg147192 - (view) Author: Ezio Melotti (ezio.melotti) * (Python committer) Date: 2011-11-06 22:51
msg147612 - (view) Author: Roundup Robot (python-dev) (Python triager) Date: 2011-11-14 16:57
New changeset 3c3009f63700 by Ezio Melotti in branch '2.7':
#1745761, #755670, #13357, #12629, #1200313: improve attribute handling in HTMLParser.

New changeset 16ed15ff0d7c by Ezio Melotti in branch '3.2':
#1745761, #755670, #13357, #12629, #1200313: improve attribute handling in HTMLParser.

New changeset 426f7a2b1826 by Ezio Melotti in branch 'default':
#1745761, #755670, #13357, #12629, #1200313: merge with 3.2.
msg147620 - (view) Author: Ezio Melotti (ezio.melotti) * (Python committer) Date: 2011-11-14 17:12
Fixed, thanks for the report!
Apparently the correct way to parse <y z=""o"" /> is:
starttag y
attribute z with value ""
attribute o"" with no value
So this is what HTMLParser does now.
Date User Action Args
2022-04-11 14:57:20adminsetgithub: 56838
2011-11-14 17:12:07ezio.melottisetstatus: open -> closed
versions: + Python 2.7
messages: + msg147620

resolution: fixed
stage: needs patch -> resolved
2011-11-14 16:57:13python-devsetnosy: + python-dev
messages: + msg147612
2011-11-14 12:44:28ezio.melottisetassignee: ezio.melotti
2011-11-06 22:51:14ezio.melottisetmessages: + msg147192
2011-11-02 17:08:43ezio.melottisetmessages: + msg146852
2011-11-02 16:53:00eric.araujosetmessages: + msg146848
2011-11-01 13:21:41ezio.melottisetfiles: + issue12629.diff

nosy: + ezio.melotti
messages: + msg146774

keywords: + patch
stage: needs patch
2011-07-29 16:24:57eric.araujosetnosy: + eric.araujo, r.david.murray
2011-07-26 18:07:46teorynsetmessages: + msg141174
2011-07-24 18:35:07teoryncreate