forked from mirrors/nixpkgs
7447fff95a
The prefix will now be correct in case of Nix env. Note, however, that creating a venv from a Nix env still does not function. This does not seem to be possible with the current approach either, because venv will copy or symlink our Python wrapper. In case it symlinks (the default) it won't see a pyvenv.cfg. If it is copied I think it should function but it does not...
40 lines
1.5 KiB
Python
40 lines
1.5 KiB
Python
"""
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This is a Nix-specific module for discovering modules built with Nix.
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The module recursively adds paths that are on `NIX_PYTHONPATH` to `sys.path`. In
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order to process possible `.pth` files `site.addsitedir` is used.
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The paths listed in `PYTHONPATH` are added to `sys.path` afterwards, but they
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will be added before the entries we add here and thus take precedence.
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Note the `NIX_PYTHONPATH` environment variable is unset in order to prevent leakage.
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Similarly, this module listens to the environment variable `NIX_PYTHONEXECUTABLE`
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and sets `sys.executable` to its value.
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"""
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import site
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import sys
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import os
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import functools
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paths = os.environ.pop('NIX_PYTHONPATH', None)
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if paths:
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functools.reduce(lambda k, p: site.addsitedir(p, k), paths.split(':'), site._init_pathinfo())
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# Check whether we are in a venv.
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# Note Python 2 does not support base_prefix so we assume we are not in a venv.
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in_venv = sys.version_info.major == 3 and sys.prefix != sys.base_prefix
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if not in_venv:
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executable = os.environ.pop('NIX_PYTHONEXECUTABLE', None)
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prefix = os.environ.pop('NIX_PYTHONPREFIX', None)
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if 'PYTHONEXECUTABLE' not in os.environ and executable is not None:
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sys.executable = executable
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if prefix is not None:
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# Because we cannot check with Python 2 whether we are in a venv,
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# creating a venv from a Nix env won't work as well with Python 2.
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# Also, note that sysconfig does not like it when sys.prefix is set to None
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sys.prefix = sys.exec_prefix = prefix
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site.PREFIXES.insert(0, prefix)
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