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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.

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paths.py
125 lines | 4.2 KiB | text/x-python | PythonLexer
"""Find files and directories which IPython uses.
"""
import os.path
import tempfile
from warnings import warn
import IPython
from IPython.utils.importstring import import_item
from IPython.utils.path import (
get_home_dir,
get_xdg_dir,
get_xdg_cache_dir,
compress_user,
_writable_dir,
ensure_dir_exists,
)
def get_ipython_dir() -> str:
"""Get the IPython directory for this platform and user.
This uses the logic in `get_home_dir` to find the home directory
and then adds .ipython to the end of the path.
"""
env = os.environ
pjoin = os.path.join
ipdir_def = '.ipython'
home_dir = get_home_dir()
xdg_dir = get_xdg_dir()
if 'IPYTHON_DIR' in env:
warn('The environment variable IPYTHON_DIR is deprecated since IPython 3.0. '
'Please use IPYTHONDIR instead.', DeprecationWarning)
ipdir = env.get('IPYTHONDIR', env.get('IPYTHON_DIR', None))
if ipdir is None:
# not set explicitly, use ~/.ipython
ipdir = pjoin(home_dir, ipdir_def)
if xdg_dir:
# Several IPython versions (up to 1.x) defaulted to .config/ipython
# on Linux. We have decided to go back to using .ipython everywhere
xdg_ipdir = pjoin(xdg_dir, 'ipython')
if _writable_dir(xdg_ipdir):
cu = compress_user
if os.path.exists(ipdir):
warn(('Ignoring {0} in favour of {1}. Remove {0} to '
'get rid of this message').format(cu(xdg_ipdir), cu(ipdir)))
elif os.path.islink(xdg_ipdir):
warn(('{0} is deprecated. Move link to {1} to '
'get rid of this message').format(cu(xdg_ipdir), cu(ipdir)))
else:
ipdir = xdg_ipdir
ipdir = os.path.normpath(os.path.expanduser(ipdir))
if os.path.exists(ipdir) and not _writable_dir(ipdir):
# ipdir exists, but is not writable
warn("IPython dir '{0}' is not a writable location,"
" using a temp directory.".format(ipdir))
ipdir = tempfile.mkdtemp()
elif not os.path.exists(ipdir):
parent = os.path.dirname(ipdir)
if not _writable_dir(parent):
# ipdir does not exist and parent isn't writable
warn("IPython parent '{0}' is not a writable location,"
" using a temp directory.".format(parent))
ipdir = tempfile.mkdtemp()
else:
os.makedirs(ipdir, exist_ok=True)
assert isinstance(ipdir, str), "all path manipulation should be str(unicode), but are not."
return ipdir
def get_ipython_cache_dir() -> str:
"""Get the cache directory it is created if it does not exist."""
xdgdir = get_xdg_cache_dir()
if xdgdir is None:
return get_ipython_dir()
ipdir = os.path.join(xdgdir, "ipython")
if not os.path.exists(ipdir) and _writable_dir(xdgdir):
ensure_dir_exists(ipdir)
elif not _writable_dir(xdgdir):
return get_ipython_dir()
return ipdir
def get_ipython_package_dir() -> str:
"""Get the base directory where IPython itself is installed."""
ipdir = os.path.dirname(IPython.__file__)
assert isinstance(ipdir, str)
return ipdir
def get_ipython_module_path(module_str):
"""Find the path to an IPython module in this version of IPython.
This will always find the version of the module that is in this importable
IPython package. This will always return the path to the ``.py``
version of the module.
"""
if module_str == 'IPython':
return os.path.join(get_ipython_package_dir(), '__init__.py')
mod = import_item(module_str)
the_path = mod.__file__.replace('.pyc', '.py')
the_path = the_path.replace('.pyo', '.py')
return the_path
def locate_profile(profile='default'):
"""Find the path to the folder associated with a given profile.
I.e. find $IPYTHONDIR/profile_whatever.
"""
from IPython.core.profiledir import ProfileDir, ProfileDirError
try:
pd = ProfileDir.find_profile_dir_by_name(get_ipython_dir(), profile)
except ProfileDirError as e:
# IOError makes more sense when people are expecting a path
raise IOError("Couldn't find profile %r" % profile) from e
return pd.location