upstream/ipython Files · IPython/utils/module_paths.py

Swallow potential exceptions from showtraceback()...

Swallow potential exceptions from showtraceback() The nbgrader project is aware of a form of cheating where students disrupt `InteractiveShell.showtraceback` in hopes of hiding exceptions to avoid losing points. They have implemented a solution to prevent this cheating from working on the client side, and have some tests to demonstrate this technique: https://github.com/jupyter/nbgrader/blob/main/nbgrader/tests/apps/files/submitted-cheat-attempt.ipynb https://github.com/jupyter/nbgrader/blob/main/nbgrader/tests/apps/files/submitted-cheat-attempt-alternative.ipynb In essence, these attacks import the interactive shell and erase the traceback handler so that their failing tests won't report failures. import IPython.core.interactiveshell IPython.core.interactiveshell.InteractiveShell.showtraceback = None The problem is that this causes an exception inside the kernel, leading to a stalled execution. The kernel has stopped working, but the client continues to wait for messages. So far, nbgrader's solution to this is to require a timeout value so the client can eventually decide it is done. This prevents allowing a value of `None` for `Execute.timeout` because this would cause a test case to infinitely hang. This commit addresses the problem by making `InteractiveShell._run_cell` a little more protective around it's call to `showtraceback()`. There is already a try/except block around running the cell. This commit adds a finally clause so that the method will _always_ return an `ExecutionResult`, even if a new exception is thrown within the except clause. For the record, the exception thrown is: TypeError: 'NoneType' object is not callable Accepting this change will allow nbgrader to update `nbgrader.preprocessors.Execute` to support a type of `Integer(allow_none=True)` as the parent `NotebookClient` intended. Discussion about this is ongoing in jupyter/nbgrader#1690.

Matthias Bussonnier - - Load All Authors

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      """Utility functions for finding modules

      Utility functions for finding modules on sys.path.

      """

      #-----------------------------------------------------------------------------

      # Copyright (c) 2011, the IPython Development Team.

      #

      # Distributed under the terms of the Modified BSD License.

      #

      # The full license is in the file COPYING.txt, distributed with this software.

      #-----------------------------------------------------------------------------

      #-----------------------------------------------------------------------------

      # Imports

      #-----------------------------------------------------------------------------

      # Stdlib imports

      import importlib

      import sys

      # Third-party imports

      # Our own imports

      #-----------------------------------------------------------------------------

      # Globals and constants

      #-----------------------------------------------------------------------------

      #-----------------------------------------------------------------------------

      # Local utilities

      #-----------------------------------------------------------------------------

      #-----------------------------------------------------------------------------

      # Classes and functions

      #-----------------------------------------------------------------------------

      def find_mod(module_name):

          """

          Find module `module_name` on sys.path, and return the path to module `module_name`.

            - If `module_name` refers to a module directory, then return path to __init__ file.

              - If `module_name` is a directory without an __init__file, return None.

            - If module is missing or does not have a `.py` or `.pyw` extension, return None.

              - Note that we are not interested in running bytecode.

            - Otherwise, return the fill path of the module.

          Parameters

          ----------

          module_name : str

          Returns

          -------

          module_path : str

              Path to module `module_name`, its __init__.py, or None,

              depending on above conditions.

          """

          spec = importlib.util.find_spec(module_name)

          module_path = spec.origin

          if module_path is None:

              if spec.loader in sys.meta_path:

                  return spec.loader

              return None

          else:

              split_path = module_path.split(".")

              if split_path[-1] in ["py", "pyw"]:

                  return module_path

              else:

                  return None

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				"""Utility functions for finding modules

				Utility functions for finding modules on sys.path.

				"""
				#-----------------------------------------------------------------------------
				# Copyright (c) 2011, the IPython Development Team.
				#
				# Distributed under the terms of the Modified BSD License.
				#
				# The full license is in the file COPYING.txt, distributed with this software.
				#-----------------------------------------------------------------------------

				#-----------------------------------------------------------------------------
				# Imports
				#-----------------------------------------------------------------------------

				# Stdlib imports
				import importlib
				import sys

				# Third-party imports

				# Our own imports


				#-----------------------------------------------------------------------------
				# Globals and constants
				#-----------------------------------------------------------------------------

				#-----------------------------------------------------------------------------
				# Local utilities
				#-----------------------------------------------------------------------------

				#-----------------------------------------------------------------------------
				# Classes and functions
				#-----------------------------------------------------------------------------

				def find_mod(module_name):
				"""
				Find module `module_name` on sys.path, and return the path to module `module_name`.

				- If `module_name` refers to a module directory, then return path to __init__ file.
				- If `module_name` is a directory without an __init__file, return None.
				- If module is missing or does not have a `.py` or `.pyw` extension, return None.
				- Note that we are not interested in running bytecode.
				- Otherwise, return the fill path of the module.

				Parameters
				----------
				module_name : str

				Returns
				-------
				module_path : str
				Path to module `module_name`, its __init__.py, or None,
				depending on above conditions.
				"""
				spec = importlib.util.find_spec(module_name)
				module_path = spec.origin
				if module_path is None:
				if spec.loader in sys.meta_path:
				return spec.loader
				return None
				else:
				split_path = module_path.split(".")
				if split_path[-1] in ["py", "pyw"]:
				return module_path
				else:
				return None