Importing freeze requires an attached stdin

[y2kbugger]

Environment

• pip version: 19.2.2
• Python version: 3.6.9
• OS: Windows

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WFastCGI runs the WSGI handler with stdin detached.

Description
pip checks state of stdin without checking whether it is attached first.

See #7034

Expected behavior

No unhandled exception.

How to Reproduce

Specifically the error occurs when you detach stdin:

import sys
sys.stdin.detach()
from pip._internal.operations import freeze

Output

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_internal\__init__.py", line 40, in <module>
    from pip._internal.cli.autocompletion import autocomplete
  File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_internal\cli\autocompletion.py", line 8, in <module>
    from pip._internal.cli.main_parser import create_main_parser
  File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_internal\cli\main_parser.py", line 11, in <module>
    from pip._internal.commands import (
  File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_internal\commands\__init__.py", line 6, in <module>
    from pip._internal.commands.completion import CompletionCommand
  File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_internal\commands\completion.py", line 6, in <module>
    from pip._internal.cli.base_command import Command
  File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_internal\cli\base_command.py", line 21, in <module>
    from pip._internal.download import PipSession
  File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_internal\download.py", line 47, in <module>
    from pip._internal.vcs import vcs
  File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_internal\vcs\__init__.py", line 12, in <module>
    import pip._internal.vcs.subversion  # noqa: F401
  File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_internal\vcs\subversion.py", line 314, in <module>
    vcs.register(Subversion)
  File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_internal\vcs\versioncontrol.py", line 165, in register
    self._registry[cls.name] = cls()
  File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_internal\vcs\subversion.py", line 180, in __init__
    use_interactive = sys.stdin.isatty()
ValueError: underlying buffer has been detached

[chrahunt]

I feel obliged to say that importing and running pip internal functions is not supported, and running pip freeze in a subprocess probably wouldn't suffer from this. Unless we can demonstrate pip misbehaving when invoked as a separate process, I think this will not go far.

That said, (legitimate) issue #2920 will need a function written to tell whether we were invoked interactively (sys.stdout.isatty() and sys.stdin.isatty()). If whoever was fixing that issue happened to check whether both streams were not detached (to avoid throwing a ValueError) and also happened to use that function for setting use_interactive here, it would probably be OK.

Let's hope whoever fixes that issue does that! :)

[cjerdonek]

If pip's code doesn't call detach(), it doesn't seem like pip should have code to make sure detach() hasn't been called, IMO.

[no-response]

This issue has been automatically closed because there has been no response to our request for more information from the original author. With only the information that is currently in the issue, we don't have enough information to take action. Please reach out if you have or find the answers we need so that we can investigate further.