from __future__ import annotations import logging import os import re import site import sys logger = logging.getLogger(__name__) _INCLUDE_SYSTEM_SITE_PACKAGES_REGEX = re.compile( r"include-system-site-packages\s*=\s*(?Ptrue|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_legacy_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: """True if we're running inside a virtual environment, False otherwise.""" return _running_under_venv() or _running_under_legacy_virtualenv() def _get_pyvenv_cfg_lines() -> list[str] | None: """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_legacy_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_legacy_virtualenv(): return _no_global_under_legacy_virtualenv() return False