Popen with shell=True yield mangled repr output

[mpkocher]

BPO	43776
Nosy	@rhettinger, @gpshead, @WildCard65, @miss-islington, @mpkocher
PRs	bpo-43776: Remove list call from args in Popen repr #25338 [3.9] bpo-43776: Remove list call from args in Popen repr (GH-25338) #26510

^{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/gpshead'
closed_at = <Date 2021-06-03.04:16:05.651>
created_at = <Date 2021-04-08.18:42:23.832>
labels = ['type-bug', 'library', '3.9', '3.10']
title = 'Popen with shell=True yield mangled repr output'
updated_at = <Date 2021-06-03.04:16:05.651>
user = 'https://github.com/mpkocher'

bugs.python.org fields:

activity = <Date 2021-06-03.04:16:05.651>
actor = 'gregory.p.smith'
assignee = 'gregory.p.smith'
closed = True
closed_date = <Date 2021-06-03.04:16:05.651>
closer = 'gregory.p.smith'
components = ['Library (Lib)']
creation = <Date 2021-04-08.18:42:23.832>
creator = 'mkocher'
dependencies = []
files = []
hgrepos = []
issue_num = 43776
keywords = ['patch', '3.9regression']
message_count = 6.0
messages = ['390542', '390579', '391751', '391757', '392171', '394983']
nosy_count = 5.0
nosy_names = ['rhettinger', 'gregory.p.smith', 'WildCard65', 'miss-islington', 'mkocher']
pr_nums = ['25338', '26510']
priority = 'normal'
resolution = 'fixed'
stage = 'commit review'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue43776'
versions = ['Python 3.9', 'Python 3.10']

[mpkocher]

When using Popen with shell=True, the output of the repr is not particularly user friendly.

When using the form p = Popen('python --version'.split()), the output is reasonably output in a user friendly form of <Popen: returncode: None args: ['python', '--version']>.

However, when running with shell=True, the output is mangled.

For example, trying to run python --help via p = Popen('python --version', shell=True) yields the following output.

<Popen: returncode: None args: ['p', 'y', 't', 'h', 'o', 'n', ' ', '-', '-',...>

The original change appears to be motivated by https://bugs.python.org/issue38724

and the PR here:

https://github.com/python/cpython/pull/17151/files

[WildCard65]

Actually, the problem is independent of the value of "shell", the __repr__ function from the initial PR that introduced it expects "args" to be a sequence and converts it to a list.

[mpkocher]

There's a PR up with removed list call as well as improved test coverage for the case where args is passed into Popen as a string.

Hopefully this can get merged before things starting getting crazy with the 3.10 release crunch.

[mpkocher]

There also appears to be an issue when args are provided as a pathlib.Path instance.

Python 3.9.2 | packaged by conda-forge | (default, Feb 21 2021, 05:02:20)
Type 'copyright', 'credits' or 'license' for more information
IPython 7.22.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: from subprocess import Popen

In [2]: from pathlib import Path

In [3]: p = Path('/usr/local/bin/gtrue')

In [4]: x = Popen(p)

In [5]: repr(x)
---------------------------------------------------------------------------

TypeError                                 Traceback (most recent call last)
<ipython-input-5-5091dd558c19> in <module>
----> 1 repr(x)

~/opt/miniconda3/envs/core/lib/python3.9/subprocess.py in __repr__(self)
990 obj_repr = (
991 f"<{self.__class__.__name__}: "
--> 992 f"returncode: {self.returncode} args: {list(self.args)!r}>"
993 )
994 if len(obj_repr) > 80:

TypeError: 'PosixPath' object is not iterable

[miss-islington]

New changeset db0c5b7 by M. Kocher in branch 'master':
bpo-43776: Remove list call from args in Popen repr (GH-25338)
db0c5b7

[gpshead]

New changeset 5a8ddcc by Gregory P. Smith in branch '3.9':
[3.9] bpo-43776: Remove list call from args in Popen repr (GH-25338) (GH-26510)
5a8ddcc