helpers: install as setuptools scripts

[hundeboll]

Allow using e.g. labgrid-bound-connect also when installing labgrid using pip.

Description We install labgrid using pip in a Containerfile, but need to use labgrid-bound-connect on the exporter. This isn't currently possible, as the two scripts in ./helpers/ aren't installed unless building a debian package.

To make it possible to configure the two helpers as scripts in pyproject.toml they must reside in the python package itself, so move the two files from ./helpers/ to ./labgrid/helpers.

Both scripts are also changed to configure/parse arguments in a function instead of the global scope, as the setuptools scripts configuration needs to call a function from the specified files.

Checklist

• [ ] Documentation for the feature
• [ ] Tests for the feature

• [ ] The arguments and description in doc/configuration.rst have been updated

• [ ] Add a section on how to use the feature to doc/usage.rst

• [ ] Add a section on how to use the feature to doc/development.rst

• [x] PR has been tested

• [ ] Man pages have been regenerated

[jluebbe]

The commit message contains a typo ("count").

Are there any security implications of calling the helpers via the setuptools wrappers?

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 55.1%. Comparing base (2ce9e24) to head (dde3b51). Report is 48 commits behind head on master.

:white_check_mark: All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
labgrid/helpers/bound_connect.py	0.0%	1 Missing :warning:
labgrid/helpers/raw_interface.py	0.0%	1 Missing :warning:

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #1633     +/-   ##
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- Coverage    55.8%   55.1%   -0.7%     
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  Files         170     172      +2     
  Lines       13382   13544    +162     
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+ Hits         7469    7472      +3     
- Misses       5913    6072    +159     

Flag	Coverage Δ
3.10	55.1% <0.0%> (-1.0%)	:arrow_down:
3.11	55.1% <0.0%> (-1.0%)	:arrow_down:
3.12	55.1% <0.0%> (-1.0%)	:arrow_down:
3.13	55.1% <0.0%> (-1.0%)	:arrow_down:
3.9	55.1% <0.0%> (-1.0%)	:arrow_down:

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[hundeboll]

Are there any security implications of calling the helpers via the setuptools wrappers?

I can see a few different scenarios:

1. labgrid checked out as root, installed as non-root (e.g. pip install --editable . in python venv) Then a malicious user can change the wrapper script, which is then called as root
2. labgrid checked out as non-root, installed as root (pip install --editable .) Then a malicious user can change the helper script, which is then called as root
3. labgrid installed as root or non-root (e.g. pip install labgrid) Only the installing user can change both the wrapper and the helper script
4. labgrid installed as debian package (e.g. dpkg -i labgrid.deb) Both wrapper and helper script are editable by root only.

Case 1 and 2 should be avoided as both helper scripts are called as root, but I don't see how that i different from today. Case 3 should take care if installing as non-root, but that is no different than calling the script directly. Case 4 dosn't change.

More or other concerns?