Blank lines in ._pth file are not ignored #73512
Description
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/zooba'
closed_at = <Date 2017-02-08.05:06:13.782>
created_at = <Date 2017-01-19.16:54:32.081>
labels = ['type-bug', '3.7', 'OS-windows']
title = 'Blank lines in ._pth file are not ignored'
updated_at = <Date 2019-05-29.00:18:03.147>
user = 'https://github.com/zooba'bugs.python.org fields:
activity = <Date 2019-05-29.00:18:03.147>
actor = 'excitoon'
assignee = 'steve.dower'
closed = True
closed_date = <Date 2017-02-08.05:06:13.782>
closer = 'ammar2'
components = ['Windows']
creation = <Date 2017-01-19.16:54:32.081>
creator = 'steve.dower'
dependencies = []
files = ['46365', '46433']
hgrepos = []
issue_num = 29326
keywords = ['patch']
message_count = 16.0
messages = ['285809', '285931', '285960', '286363', '286432', '287007', '287013', '287018', '318033', '318126', '318182', '318184', '318196', '318198', '318199', '318200']
nosy_count = 10.0
nosy_names = ['paul.moore', 'tim.golden', 'r.david.murray', 'python-dev', 'zach.ware', 'steve.dower', 'Malcolm Smith', 'ammar2', 'izbyshev', 'excitoon']
pr_nums = ['7243']
priority = 'low'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue29326'
versions = ['Python 3.6', 'Python 3.7']
Activity
zooba commentedon Jan 19, 2017
If a python._pth file includes a blank line, it gets treated as '\n' which is then appended to the directory and used as an entry in sys.path.
Empty lines should be ignored completely.
ammaraskar commentedon Jan 21, 2017
I've attached a patch that makes the site package ignore empty lines in .pth files. Along with a test for this behavior. I'm not really familiar with the site machinery so I hope the test and code are fine.
zooba commentedon Jan 21, 2017
The fix for this issue is needed in PC/getpathp.c as this is a special feature in path generation on Windows.
I'm not aware of any such issue with .pth files - the underscore in ._pth is deliberate.
izbyshev commentedon Jan 27, 2017
I've encountered this issue too. (FYI, the official 3.6.0 embeddable zip from https://www.python.org/downloads/windows/ does contain a blank line in its ._pth, so all its users get an invalid entry in sys.path).
The patch is attached. I couldn't fix tests in more straightforward way because both of them were broken:
I've strengthened the check in 'nosite' test because it is trivial to fully emulate sys.path calculation logic in this case. I've preserved weaker checks in the other test because I didn't want to emulate site.py logic.
zooba commentedon Jan 29, 2017
I haven't had a chance to try the patch (underpth_blank_lines.diff) or apply it, but it looks right.
If one of the other core devs gets to apply this before I do, feel free.
Alexey, you don't need to sign a CLA for this fix, but if you're going to contribute more then you may want to: https://docs.python.org/devguide/committing.html#contributor-licensing-agreements It's all online, and it'll help save the core developers from having to evaluate whether you need it or not (which I can do, because it comes up often for me in my day job, but not everyone has that experience). And thanks for this patch!
python-dev commentedon Feb 4, 2017
New changeset 54fea351e3f9 by Steve Dower in branch '3.6':
Issue bpo-29326: Ignores blank lines in ._pth files (Patch by Alexey Izbyshev)
https://hg.python.org/cpython/rev/54fea351e3f9
New changeset a0ff777ab153 by Steve Dower in branch 'default':
Issue bpo-29326: Ignores blank lines in ._pth files (Patch by Alexey Izbyshev)
https://hg.python.org/cpython/rev/a0ff777ab153
python-dev commentedon Feb 5, 2017
New changeset 6d90b135e36c5b2794a29f650ebebf8bbd96f3fb by Steve Dower in branch 'master':
Issue bpo-29326: Ignores blank lines in ._pth files (Patch by Alexey Izbyshev)
6d90b13
New changeset 3ba099c135cdbced6c2ff168a90a689a83b376db by Steve Dower in branch 'master':
Issue bpo-29326: Ignores blank lines in ._pth files (Patch by Alexey Izbyshev)
3ba099c
python-dev commentedon Feb 5, 2017
New changeset 6d90b135e36c5b2794a29f650ebebf8bbd96f3fb by Steve Dower in branch '3.6':
Issue bpo-29326: Ignores blank lines in ._pth files (Patch by Alexey Izbyshev)
6d90b13
mhsmith commentedon May 29, 2018
An identical issue *does* exist for .pth files. As you can see from examining site.addpackage, it does not ignore blank lines as the documentation says. Ammar's patch should also be applied.
zooba commentedon May 29, 2018
Please create a new issue. This one is closed.
excitoon commentedon May 30, 2018
Hi.
I guess this issue has to be reopen because Alexey erroneously broke adding empty paths to
sys.pathalong with his patch.Official embeddable Pythons do contain a blank line in its ._pth, and this allowed users to import modules from script directory.
Kind regards,
Vladimir.
excitoon commentedon May 30, 2018
I shall attach pull request soon.
zooba commentedon May 30, 2018
The python._pth file generated for the embeddable distribution includes ".", which allows you to import from the dist directory. The blank line should be ignored.
If you want to misuse the embeddable distribution by not restricting its search paths, delete the ._pth file.
excitoon commentedon May 30, 2018
Hi Steve.
I'll try to explain what is my motivation.
I need a reliable way to run Python (not matter embedded or not) in isolated mode, but still having current directory in
sys.path(empty entry).Ironically I could misuse normal mode to simulate isolated mode with specified %PYTHONPATH% (which is not much handy, by the way), but hiding Windows Registry keys would look pretty hard (it is impossible to make a bat/cmd wrapper). Possibility to search %PYTHONPATH% in HKLM entries makes it even worse.
Empty entry in
sys.pathis a extremely popular thing, and many software depend on it. It looks like a bug that isolated mode cannot support such entry.# How would I fix it.
Possibly we should allow another keyword for adding an empty entry (like we have an exclusion for
import site).Ideas are appreciated.
mhsmith commentedon May 30, 2018
FYI: I have created bpo-33689 for the non-Windows-specific issue.
bitdancer commentedon May 30, 2018
Vladimir, please open a new issue for this feature request. This issue is closed.