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EDIT :: _virtualenv.py

"""Patches that are applied at runtime to the virtual environment.""" from __future__ import annotations import os import sys VIRTUALENV_PATCH_FILE = os.path.join(__file__) def patch_dist(dist): """ Distutils allows user to configure some arguments via a configuration file: https://docs.python.org/3/install/index.html#distutils-configuration-files. Some of this arguments though don't make sense in context of the virtual environment files, let's fix them up. """ # noqa: D205 # we cannot allow some install config as that would get packages installed outside of the virtual environment old_parse_config_files = dist.Distribution.parse_config_files def parse_config_files(self, *args, **kwargs): result = old_parse_config_files(self, *args, **kwargs) install = self.get_option_dict("install") if "prefix" in install: # the prefix governs where to install the libraries install["prefix"] = VIRTUALENV_PATCH_FILE, os.path.abspath(sys.prefix) for base in ("purelib", "platlib", "headers", "scripts", "data"): key = f"install_{base}" if key in install: # do not allow global configs to hijack venv paths install.pop(key, None) return result dist.Distribution.parse_config_files = parse_config_files # Import hook that patches some modules to ignore configuration values that break package installation in case # of virtual environments. _DISTUTILS_PATCH = "distutils.dist", "setuptools.dist" # https://docs.python.org/3/library/importlib.html#setting-up-an-importer class _Finder: """A meta path finder that allows patching the imported distutils modules.""" fullname = None # lock[0] is threading.Lock(), but initialized lazily to avoid importing threading very early at startup, # because there are gevent-based applications that need to be first to import threading by themselves. # See https://github.com/pypa/virtualenv/issues/1895 for details. lock = [] # noqa: RUF012 def find_spec(self, fullname, path, target=None): # noqa: ARG002 if fullname in _DISTUTILS_PATCH and self.fullname is None: # noqa: PLR1702 # initialize lock[0] lazily if len(self.lock) == 0: import threading # noqa: PLC0415 lock = threading.Lock() # there is possibility that two threads T1 and T2 are simultaneously running into find_spec, # observing .lock as empty, and further going into hereby initialization. However due to the GIL, # list.append() operation is atomic and this way only one of the threads will "win" to put the lock # - that every thread will use - into .lock[0]. # https://docs.python.org/3/faq/library.html#what-kinds-of-global-value-mutation-are-thread-safe self.lock.append(lock) from functools import partial # noqa: PLC0415 from importlib.util import find_spec # noqa: PLC0415 with self.lock[0]: self.fullname = fullname try: spec = find_spec(fullname, path) if spec is not None: # https://www.python.org/dev/peps/pep-0451/#how-loading-will-work is_new_api = hasattr(spec.loader, "exec_module") func_name = "exec_module" if is_new_api else "load_module" old = getattr(spec.loader, func_name) func = self.exec_module if is_new_api else self.load_module if old is not func: try: # noqa: SIM105 setattr(spec.loader, func_name, partial(func, old)) except AttributeError: pass # C-Extension loaders are r/o such as zipimporter with <3.7 return spec finally: self.fullname = None return None @staticmethod def exec_module(old, module): old(module) if module.__name__ in _DISTUTILS_PATCH: patch_dist(module) @staticmethod def load_module(old, name): module = old(name) if module.__name__ in _DISTUTILS_PATCH: patch_dist(module) return module sys.meta_path.insert(0, _Finder())

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