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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() -> 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() -> 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() -> 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() -> 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() -> 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() -> 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() -> 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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