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- import logging
- import os
- import re
- import site
- import sys
- from typing import List, Optional
- logger = logging.getLogger(__name__)
- _INCLUDE_SYSTEM_SITE_PACKAGES_REGEX = re.compile(
- r"include-system-site-packages\s*=\s*(?P<value>true|false)"
- )
- def _running_under_venv():
- # type: () -> bool
- """Checks if sys.base_prefix and sys.prefix match.
- This handles PEP 405 compliant virtual environments.
- """
- return sys.prefix != getattr(sys, "base_prefix", sys.prefix)
- def _running_under_regular_virtualenv():
- # type: () -> bool
- """Checks if sys.real_prefix is set.
- This handles virtual environments created with pypa's virtualenv.
- """
- # pypa/virtualenv case
- return hasattr(sys, "real_prefix")
- def running_under_virtualenv():
- # type: () -> bool
- """Return True if we're running inside a virtualenv, False otherwise."""
- return _running_under_venv() or _running_under_regular_virtualenv()
- def _get_pyvenv_cfg_lines():
- # type: () -> Optional[List[str]]
- """Reads {sys.prefix}/pyvenv.cfg and returns its contents as list of lines
- Returns None, if it could not read/access the file.
- """
- pyvenv_cfg_file = os.path.join(sys.prefix, "pyvenv.cfg")
- try:
- # Although PEP 405 does not specify, the built-in venv module always
- # writes with UTF-8. (pypa/pip#8717)
- with open(pyvenv_cfg_file, encoding="utf-8") as f:
- return f.read().splitlines() # avoids trailing newlines
- except OSError:
- return None
- def _no_global_under_venv():
- # type: () -> bool
- """Check `{sys.prefix}/pyvenv.cfg` for system site-packages inclusion
- PEP 405 specifies that when system site-packages are not supposed to be
- visible from a virtual environment, `pyvenv.cfg` must contain the following
- line:
- include-system-site-packages = false
- Additionally, log a warning if accessing the file fails.
- """
- cfg_lines = _get_pyvenv_cfg_lines()
- if cfg_lines is None:
- # We're not in a "sane" venv, so assume there is no system
- # site-packages access (since that's PEP 405's default state).
- logger.warning(
- "Could not access 'pyvenv.cfg' despite a virtual environment "
- "being active. Assuming global site-packages is not accessible "
- "in this environment."
- )
- return True
- for line in cfg_lines:
- match = _INCLUDE_SYSTEM_SITE_PACKAGES_REGEX.match(line)
- if match is not None and match.group("value") == "false":
- return True
- return False
- def _no_global_under_regular_virtualenv():
- # type: () -> bool
- """Check if "no-global-site-packages.txt" exists beside site.py
- This mirrors logic in pypa/virtualenv for determining whether system
- site-packages are visible in the virtual environment.
- """
- site_mod_dir = os.path.dirname(os.path.abspath(site.__file__))
- no_global_site_packages_file = os.path.join(
- site_mod_dir,
- "no-global-site-packages.txt",
- )
- return os.path.exists(no_global_site_packages_file)
- def virtualenv_no_global():
- # type: () -> bool
- """Returns a boolean, whether running in venv with no system site-packages."""
- # PEP 405 compliance needs to be checked first since virtualenv >=20 would
- # return True for both checks, but is only able to use the PEP 405 config.
- if _running_under_venv():
- return _no_global_under_venv()
- if _running_under_regular_virtualenv():
- return _no_global_under_regular_virtualenv()
- return False
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