Method minimum_sys_modules

pex/pex.py:296–357

Given a set of site-packages paths, return a "clean" sys.modules. When importing site, modules within `sys.modules` have their `__path__`s populated with additional paths as defined by `*-nspkg.pth` in `site-packages`, or alternately by distribution metadata such as `*.dist-

(
        cls,
        isolated_sys_path,  # type: IsolatedSysPath
        modules=None,  # type: Optional[Mapping[str, ModuleType]]
    )

    @classmethod
    def minimum_sys_modules(
        cls,
        isolated_sys_path,  # type: IsolatedSysPath
        modules=None,  # type: Optional[Mapping[str, ModuleType]]
    ):
        # type: (...) -> Mapping[str, ModuleType]
        """Given a set of site-packages paths, return a "clean" sys.modules.

        When importing site, modules within `sys.modules` have their `__path__`s populated with
        additional paths as defined by `*-nspkg.pth` in `site-packages`, or alternately by
        distribution metadata such as `*.dist-info/namespace_packages.txt`. This can possibly cause
        namespace packages to leak into imports despite being scrubbed from `sys.path`.

        NOTE: This method mutates modules' `__path__` attributes in `sys.modules`, so this is
        currently an irreversible operation.
        """

        is_venv = isolated_sys_path.is_venv
        modules = modules or sys.modules
        new_modules = {}

        for module_name, module in modules.items():
            # Tainted modules should be dropped.
            module_file = getattr(module, "__file__", None)
            if (
                # The `_virtualenv` module is a known special case provided by the virtualenv
                # project. It should not be un-imported or else the virtualenv importer it installs
                # for performing needed patches to the `distutils` stdlib breaks.
                #
                # See:
                # + https://github.com/pex-tool/pex/issues/992
                # + https://github.com/pypa/virtualenv/pull/1688
                (not is_venv or module_name != "_virtualenv")
                and module_file
                and module_file not in isolated_sys_path
            ):
                TRACER.log("Dropping %s" % (module_name,), V=3)
                continue

            module_path = getattr(module, "__path__", None)
            # Untainted non-packages (builtin modules) need no further special handling and can
            # stay.
            if module_path is None:
                new_modules[module_name] = module
                continue

            # Unexpected objects, e.g. PEP 420 namespace packages, should just be dropped.
            if not isinstance(module_path, list):
                TRACER.log("Dropping %s" % (module_name,), V=3)
                continue

            # Drop tainted package paths.
            for k in reversed(range(len(module_path))):
                if module_path[k] not in isolated_sys_path:
                    TRACER.log("Scrubbing %s.__path__: %s" % (module_name, module_path[k]), V=3)
                    module_path.pop(k)

            # The package still contains untainted path elements, so it can stay.