307 lines
10 KiB
Python
307 lines
10 KiB
Python
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"""runpy.py - locating and running Python code using the module namespace
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Provides support for locating and running Python scripts using the Python
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module namespace instead of the native filesystem.
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This allows Python code to play nicely with non-filesystem based PEP 302
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importers when locating support scripts as well as when importing modules.
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"""
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# Written by Nick Coghlan <ncoghlan at gmail.com>
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# to implement PEP 338 (Executing Modules as Scripts)
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# This is a modified version of runpy.py, lifted from Python 3.9.2
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# The main difference is that this version does NOT restore sys.modules["__main__"]
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import importlib.machinery # importlib first so we can test #15386 via -m
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import importlib.util
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import io
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import os
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import sys
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from pkgutil import get_importer, read_code
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from .rescript import split_script
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__all__ = [
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"run_module",
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"run_path",
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]
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class _ModifiedArgv0(object):
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def __init__(self, value):
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self.value = value
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self._saved_value = self._sentinel = object()
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def __enter__(self):
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if self._saved_value is not self._sentinel:
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raise RuntimeError("Already preserving saved value")
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self._saved_value = sys.argv[0]
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sys.argv[0] = self.value
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def __exit__(self, *args):
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self.value = self._sentinel
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sys.argv[0] = self._saved_value
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# TODO: Replace these helpers with importlib._bootstrap_external functions.
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def _run_code(
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code,
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run_globals,
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init_globals=None,
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mod_name=None,
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mod_spec=None,
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pkg_name=None,
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script_name=None,
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prepare=None,
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):
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"""Helper to run code in nominated namespace"""
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if init_globals is not None:
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run_globals.update(init_globals)
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if mod_spec is None:
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loader = None
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fname = script_name
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cached = None
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else:
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loader = mod_spec.loader
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fname = mod_spec.origin
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cached = mod_spec.cached
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if pkg_name is None:
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pkg_name = mod_spec.parent
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run_globals.update(
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__name__=mod_name,
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__file__=fname,
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__cached__=cached,
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__doc__=None,
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__loader__=loader,
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__package__=pkg_name,
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__spec__=mod_spec,
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)
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if isinstance(code, tuple):
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before, after = code
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exec(before, run_globals)
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if prepare is not None:
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prepare(run_globals)
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exec(after, run_globals)
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else:
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exec(code, run_globals)
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if prepare is not None:
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prepare(run_globals)
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return run_globals
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def _run_module_code(
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code,
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init_globals=None,
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module_object=None,
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mod_spec=None,
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pkg_name=None,
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script_name=None,
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prepare=None,
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):
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"""Helper to run code in new namespace with sys modified"""
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fname = script_name if mod_spec is None else mod_spec.origin
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mod_name = module_object.__name__
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temp_module = module_object
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sys.modules[mod_name] = temp_module
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with _ModifiedArgv0(fname):
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mod_globals = temp_module.__dict__
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_run_code(
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code,
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mod_globals,
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init_globals,
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mod_name,
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mod_spec,
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pkg_name,
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script_name,
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prepare=prepare,
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)
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return temp_module
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# Helper to get the full name, spec and code for a module
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def _get_module_details(mod_name, error=ImportError):
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if mod_name.startswith("."):
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raise error("Relative module names not supported")
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pkg_name, _, _ = mod_name.rpartition(".")
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if pkg_name:
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# Try importing the parent to avoid catching initialization errors
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try:
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__import__(pkg_name)
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except ImportError as e:
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# If the parent or higher ancestor package is missing, let the
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# error be raised by find_spec() below and then be caught. But do
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# not allow other errors to be caught.
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if e.name is None or (
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e.name != pkg_name and not pkg_name.startswith(e.name + ".")
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):
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raise
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# Warn if the module has already been imported under its normal name
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existing = sys.modules.get(mod_name)
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if existing is not None and not hasattr(existing, "__path__"):
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from warnings import warn
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msg = (
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"{mod_name!r} found in sys.modules after import of "
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"package {pkg_name!r}, but prior to execution of "
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"{mod_name!r}; this may result in unpredictable "
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"behaviour".format(mod_name=mod_name, pkg_name=pkg_name)
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)
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warn(RuntimeWarning(msg))
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try:
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spec = importlib.util.find_spec(mod_name)
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except (ImportError, AttributeError, TypeError, ValueError) as ex:
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# This hack fixes an impedance mismatch between pkgutil and
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# importlib, where the latter raises other errors for cases where
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# pkgutil previously raised ImportError
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msg = "Error while finding module specification for {!r} ({}: {})"
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if mod_name.endswith(".py"):
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msg += (
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f". Try using '{mod_name[:-3]}' instead of "
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f"'{mod_name}' as the module name."
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)
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raise error(msg.format(mod_name, type(ex).__name__, ex)) from ex
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if spec is None:
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raise error("No module named %s" % mod_name)
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if spec.submodule_search_locations is not None:
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if mod_name == "__main__" or mod_name.endswith(".__main__"):
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raise error("Cannot use package as __main__ module")
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try:
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pkg_main_name = mod_name + ".__main__"
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return _get_module_details(pkg_main_name, error)
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except error as e:
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if mod_name not in sys.modules:
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raise # No module loaded; being a package is irrelevant
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raise error(
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("%s; %r is a package and cannot " + "be directly executed")
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% (e, mod_name)
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)
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loader = spec.loader
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if loader is None:
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raise error(
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"%r is a namespace package and cannot be executed" % mod_name
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)
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try:
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code = loader.get_code(mod_name)
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except ImportError as e:
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raise error(format(e)) from e
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if code is None:
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raise error("No code object available for %s" % mod_name)
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return mod_name, spec, code
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def run_module(
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mod_name,
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init_globals=None,
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module_object=None,
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alter_sys=True,
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prepare=None,
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):
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"""Execute a module's code without importing it
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Returns the resulting top level namespace dictionary
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"""
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mod_name, mod_spec, code = _get_module_details(mod_name)
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if alter_sys:
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return _run_module_code(
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code, init_globals, module_object, mod_spec, prepare=prepare
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)
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else:
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# Leave the sys module alone
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return _run_code(
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code,
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module_object.__dict__,
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init_globals,
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module_object.__name__,
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mod_spec,
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prepare=prepare,
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)
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def _get_main_module_details(error=ImportError):
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# Helper that gives a nicer error message when attempting to
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# execute a zipfile or directory by invoking __main__.py
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# Also moves the standard __main__ out of the way so that the
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# preexisting __loader__ entry doesn't cause issues
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main_name = "__main__"
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saved_main = sys.modules[main_name]
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del sys.modules[main_name]
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try:
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return _get_module_details(main_name)
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except ImportError as exc:
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if main_name in str(exc):
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raise error(
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"can't find %r module in %r" % (main_name, sys.path[0])
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) from exc
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raise
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finally:
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sys.modules[main_name] = saved_main
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def _get_code_from_file(run_name, fname):
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# Check for a compiled file first
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decoded_path = os.path.abspath(os.fsdecode(fname))
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with io.open_code(decoded_path) as f:
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code = read_code(f)
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if code is None:
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# That didn't work, so try it as normal source code
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code = split_script(fname)
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return code, fname
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def run_path(path_name, module_object, init_globals=None, prepare=None):
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"""Execute code located at the specified filesystem location
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Returns the resulting top level namespace dictionary
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The file path may refer directly to a Python script (i.e.
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one that could be directly executed with execfile) or else
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it may refer to a zipfile or directory containing a top
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level __main__.py script.
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"""
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run_name = pkg_name = module_object.__name__
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importer = get_importer(path_name)
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# Trying to avoid importing imp so as to not consume the deprecation warning.
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is_NullImporter = False
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if type(importer).__module__ == "imp":
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if type(importer).__name__ == "NullImporter":
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is_NullImporter = True
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if isinstance(importer, type(None)) or is_NullImporter:
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# Not a valid sys.path entry, so run the code directly
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# execfile() doesn't help as we want to allow compiled files
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code, fname = _get_code_from_file(run_name, path_name)
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return _run_module_code(
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code,
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init_globals,
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module_object,
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pkg_name=pkg_name,
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script_name=fname,
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prepare=prepare,
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)
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else:
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# Finder is defined for path, so add it to
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# the start of sys.path
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sys.path.insert(0, path_name)
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try:
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# Here's where things are a little different from the run_module
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# case. There, we only had to replace the module in sys while the
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# code was running and doing so was somewhat optional. Here, we
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# have no choice and we have to remove it even while we read the
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# code. If we don't do this, a __loader__ attribute in the
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# existing __main__ module may prevent location of the new module.
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mod_name, mod_spec, code = _get_main_module_details()
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temp_module = module_object
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sys.modules[run_name] = temp_module
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with _ModifiedArgv0(path_name):
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mod_globals = temp_module.__dict__
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_run_code(
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code,
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mod_globals,
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init_globals,
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run_name,
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mod_spec,
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pkg_name,
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prepare=prepare,
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)
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return temp_module
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finally:
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try:
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sys.path.remove(path_name)
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except ValueError:
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pass
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