Windows ChimeraX does not crash on access violation

[goddard@…]

The following bug report has been submitted:
Platform:        Windows-10-10.0.19043
ChimeraX Version: 1.5.dev202205210047 (2022-05-21 00:47:34 UTC)
Description
Opening a script intended to crash ChimeraX (for testing bug reporting) surprisingly does not crash it on Windows.  Instead it gives this OSError access violation message and keeps running.

import ctypes
ctypes.string_at(0)


Log:
UCSF ChimeraX version: 1.5.dev202205210047 (2022-05-21)  
© 2016-2022 Regents of the University of California. All rights reserved.  
How to cite UCSF ChimeraX  

> open test_crash.py

Traceback (most recent call last):  
File "test_crash.py", line 2, in <module>  
ctypes.string_at(0)  
File
"C:\cygwin64\home\goddard\ucsf\chimerax\ChimeraX.app\bin\lib\ctypes\\__init__.py",
line 517, in string_at  
return _string_at(ptr, size)  
OSError: exception: access violation reading 0x0000000000000000  
  
Error opening python file test_crash.py  




OpenGL version: 3.3.0 NVIDIA 456.71
OpenGL renderer: GeForce GTX 1080 Ti/PCIe/SSE2
OpenGL vendor: NVIDIA Corporation

Python: 3.9.11
Locale: en_US.cp1252
Qt version: PyQt6 6.3.0, Qt 6.3.0
Qt runtime version: 6.3.0
Qt platform: windows

Manufacturer: Gigabyte Technology Co., Ltd.
Model: Z270X-Gaming K7
OS: Microsoft Windows 10 Home (Build 19043)
Memory: 17,129,693,184
MaxProcessMemory: 137,438,953,344
CPU: 8 Intel(R) Core(TM) i7-7700K CPU @ 4.20GHz
OSLanguage: en-US

Installed Packages:
    alabaster: 0.7.12
    appdirs: 1.4.4
    Babel: 2.10.1
    backcall: 0.2.0
    blockdiag: 3.0.0
    build: 0.7.0
    certifi: 2022.5.18.1
    cftime: 1.6.0
    charset-normalizer: 2.0.12
    ChimeraX-AddCharge: 1.2.3
    ChimeraX-AddH: 2.1.11
    ChimeraX-AlignmentAlgorithms: 2.0
    ChimeraX-AlignmentHdrs: 3.2.1
    ChimeraX-AlignmentMatrices: 2.0
    ChimeraX-Alignments: 2.4.3
    ChimeraX-AlphaFold: 1.0
    ChimeraX-AltlocExplorer: 1.0.2
    ChimeraX-AmberInfo: 1.0
    ChimeraX-Arrays: 1.0
    ChimeraX-Atomic: 1.39.2
    ChimeraX-AtomicLibrary: 7.0
    ChimeraX-AtomSearch: 2.0.1
    ChimeraX-AxesPlanes: 2.1
    ChimeraX-BasicActions: 1.1
    ChimeraX-BILD: 1.0
    ChimeraX-BlastProtein: 2.1.1
    ChimeraX-BondRot: 2.0
    ChimeraX-BugReporter: 1.0
    ChimeraX-BuildStructure: 2.7
    ChimeraX-Bumps: 1.0
    ChimeraX-BundleBuilder: 1.2
    ChimeraX-ButtonPanel: 1.0
    ChimeraX-CageBuilder: 1.0
    ChimeraX-CellPack: 1.0
    ChimeraX-Centroids: 1.2
    ChimeraX-ChemGroup: 2.0
    ChimeraX-Clashes: 2.2.4
    ChimeraX-ColorActions: 1.0
    ChimeraX-ColorGlobe: 1.0
    ChimeraX-ColorKey: 1.5.1
    ChimeraX-CommandLine: 1.2.3
    ChimeraX-ConnectStructure: 2.0.1
    ChimeraX-Contacts: 1.0
    ChimeraX-Core: 1.5.dev202205210047
    ChimeraX-CoreFormats: 1.1
    ChimeraX-coulombic: 1.3.2
    ChimeraX-Crosslinks: 1.0
    ChimeraX-Crystal: 1.0
    ChimeraX-CrystalContacts: 1.0
    ChimeraX-DataFormats: 1.2.2
    ChimeraX-Dicom: 1.1
    ChimeraX-DistMonitor: 1.1.5
    ChimeraX-Dssp: 2.0
    ChimeraX-EMDB-SFF: 1.0
    ChimeraX-ExperimentalCommands: 1.0
    ChimeraX-FileHistory: 1.0
    ChimeraX-FunctionKey: 1.0
    ChimeraX-Geometry: 1.2
    ChimeraX-gltf: 1.0
    ChimeraX-Graphics: 1.1
    ChimeraX-Hbonds: 2.1.2
    ChimeraX-Help: 1.2
    ChimeraX-HKCage: 1.3
    ChimeraX-IHM: 1.1
    ChimeraX-ImageFormats: 1.2
    ChimeraX-IMOD: 1.0
    ChimeraX-IO: 1.0.1
    ChimeraX-ItemsInspection: 1.0
    ChimeraX-Label: 1.1.1
    ChimeraX-ListInfo: 1.1.1
    ChimeraX-Log: 1.1.5
    ChimeraX-LookingGlass: 1.1
    ChimeraX-Maestro: 1.8.1
    ChimeraX-Map: 1.1
    ChimeraX-MapData: 2.0
    ChimeraX-MapEraser: 1.0
    ChimeraX-MapFilter: 2.0
    ChimeraX-MapFit: 2.0
    ChimeraX-MapSeries: 2.1
    ChimeraX-Markers: 1.0
    ChimeraX-Mask: 1.0
    ChimeraX-MatchMaker: 2.0.6
    ChimeraX-MDcrds: 2.6
    ChimeraX-MedicalToolbar: 1.0.1
    ChimeraX-Meeting: 1.0
    ChimeraX-MLP: 1.1
    ChimeraX-mmCIF: 2.7
    ChimeraX-MMTF: 2.1
    ChimeraX-Modeller: 1.5.5
    ChimeraX-ModelPanel: 1.3.2
    ChimeraX-ModelSeries: 1.0
    ChimeraX-Mol2: 2.0
    ChimeraX-Morph: 1.0
    ChimeraX-MouseModes: 1.1
    ChimeraX-Movie: 1.0
    ChimeraX-Neuron: 1.0
    ChimeraX-Nucleotides: 2.0.2
    ChimeraX-OpenCommand: 1.9
    ChimeraX-PDB: 2.6.6
    ChimeraX-PDBBio: 1.0
    ChimeraX-PDBLibrary: 1.0.2
    ChimeraX-PDBMatrices: 1.0
    ChimeraX-PickBlobs: 1.0
    ChimeraX-Positions: 1.0
    ChimeraX-PresetMgr: 1.1
    ChimeraX-PubChem: 2.1
    ChimeraX-ReadPbonds: 1.0.1
    ChimeraX-Registration: 1.1
    ChimeraX-RemoteControl: 1.0
    ChimeraX-ResidueFit: 1.0
    ChimeraX-RestServer: 1.1
    ChimeraX-RNALayout: 1.0
    ChimeraX-RotamerLibMgr: 2.0.1
    ChimeraX-RotamerLibsDunbrack: 2.0
    ChimeraX-RotamerLibsDynameomics: 2.0
    ChimeraX-RotamerLibsRichardson: 2.0
    ChimeraX-SaveCommand: 1.5.1
    ChimeraX-SchemeMgr: 1.0
    ChimeraX-SDF: 2.0
    ChimeraX-Segger: 1.0
    ChimeraX-Segment: 1.0
    ChimeraX-SelInspector: 1.0
    ChimeraX-SeqView: 2.6
    ChimeraX-Shape: 1.0.1
    ChimeraX-Shell: 1.0
    ChimeraX-Shortcuts: 1.1
    ChimeraX-ShowAttr: 1.0
    ChimeraX-ShowSequences: 1.0
    ChimeraX-SideView: 1.0
    ChimeraX-Smiles: 2.1
    ChimeraX-SmoothLines: 1.0
    ChimeraX-SpaceNavigator: 1.0
    ChimeraX-StdCommands: 1.8
    ChimeraX-STL: 1.0
    ChimeraX-Storm: 1.0
    ChimeraX-StructMeasure: 1.0.1
    ChimeraX-Struts: 1.0.1
    ChimeraX-Surface: 1.0
    ChimeraX-SwapAA: 2.0
    ChimeraX-SwapRes: 2.1.1
    ChimeraX-TapeMeasure: 1.0
    ChimeraX-Test: 1.0
    ChimeraX-Toolbar: 1.1.1
    ChimeraX-ToolshedUtils: 1.2.1
    ChimeraX-Tug: 1.0
    ChimeraX-UI: 1.20.1
    ChimeraX-uniprot: 2.2
    ChimeraX-UnitCell: 1.0
    ChimeraX-ViewDockX: 1.1.2
    ChimeraX-VIPERdb: 1.0
    ChimeraX-Vive: 1.1
    ChimeraX-VolumeMenu: 1.0
    ChimeraX-VTK: 1.0
    ChimeraX-WavefrontOBJ: 1.0
    ChimeraX-WebCam: 1.0
    ChimeraX-WebServices: 1.1.0
    ChimeraX-Zone: 1.0
    colorama: 0.4.4
    comtypes: 1.1.10
    cxservices: 1.2
    cycler: 0.11.0
    Cython: 0.29.26
    debugpy: 1.6.0
    decorator: 5.1.1
    docutils: 0.17.1
    entrypoints: 0.4
    filelock: 3.4.2
    fonttools: 4.33.3
    funcparserlib: 1.0.0
    grako: 3.16.5
    h5py: 3.6.0
    html2text: 2020.1.16
    idna: 3.3
    ihm: 0.27
    imagecodecs: 2021.11.20
    imagesize: 1.3.0
    ipykernel: 6.6.1
    ipython: 7.31.1
    ipython-genutils: 0.2.0
    jedi: 0.18.1
    Jinja2: 3.0.3
    jupyter-client: 7.1.0
    jupyter-core: 4.10.0
    kiwisolver: 1.4.2
    line-profiler: 3.4.0
    lxml: 4.7.1
    lz4: 3.1.10
    MarkupSafe: 2.1.1
    matplotlib: 3.5.1
    matplotlib-inline: 0.1.3
    msgpack: 1.0.3
    nest-asyncio: 1.5.5
    netCDF4: 1.5.8
    networkx: 2.6.3
    numexpr: 2.8.1
    numpy: 1.22.1
    openvr: 1.16.802
    packaging: 21.3
    ParmEd: 3.4.3
    parso: 0.8.3
    pep517: 0.12.0
    pickleshare: 0.7.5
    Pillow: 9.0.1
    pip: 21.3.1
    pkginfo: 1.8.2
    prompt-toolkit: 3.0.29
    psutil: 5.9.0
    pycollada: 0.7.2
    pydicom: 2.2.2
    Pygments: 2.11.2
    PyOpenGL: 3.1.5
    PyOpenGL-accelerate: 3.1.5
    pyparsing: 3.0.9
    PyQt6: 6.3.0
    PyQt6-Qt6: 6.3.0
    PyQt6-sip: 13.3.1
    PyQt6-WebEngine: 6.3.0
    PyQt6-WebEngine-Qt6: 6.3.0
    python-dateutil: 2.8.2
    pytz: 2022.1
    pywin32: 303
    pyzmq: 23.0.0
    qtconsole: 5.3.0
    QtPy: 2.1.0
    RandomWords: 0.3.0
    requests: 2.27.1
    scipy: 1.7.3
    setuptools: 59.8.0
    sfftk-rw: 0.7.2
    six: 1.16.0
    snowballstemmer: 2.2.0
    sortedcontainers: 2.4.0
    Sphinx: 4.3.2
    sphinx-autodoc-typehints: 1.15.2
    sphinxcontrib-applehelp: 1.0.2
    sphinxcontrib-blockdiag: 3.0.0
    sphinxcontrib-devhelp: 1.0.2
    sphinxcontrib-htmlhelp: 2.0.0
    sphinxcontrib-jsmath: 1.0.1
    sphinxcontrib-qthelp: 1.0.3
    sphinxcontrib-serializinghtml: 1.1.5
    suds-community: 1.0.0
    tables: 3.7.0
    tifffile: 2021.11.2
    tinyarray: 1.2.4
    tomli: 2.0.1
    tornado: 6.1
    traitlets: 5.1.1
    urllib3: 1.26.9
    wcwidth: 0.2.5
    webcolors: 1.11.1
    wheel: 0.37.1
    wheel-filename: 1.3.0
    WMI: 1.5.1

[Tom Goddard]

It also does not crash when this code is typed to the shell. If I don't register faulthandler it still does not crash, same behavior.

On Mac it does crash.

[Tom Goddard]

Maybe this is some special ctypes behavior. If I dereference a (float *)NULL pointer in contour.cpp in Windows ChimeraX it does crash, and faulthandler gives a correct Python stack trace.

[Tom Goddard]

The Python 3.10 ctypes documentation explains this "On Windows, ctypes uses win32 structured exception handling to prevent crashes from general protection faults when functions are called with invalid argument values:"

This seems horrible. In ChimeraX it does not even offer a report a bug button because the OSError is handled when opening the script. So we won't get bug reports for these access violations. This may explain why we sometimes have seen Windows crash reports with multiple access violations.

[Tom Goddard]

I was not able to find online what kinds of errors ctypes will catch using Python "structured exception handling". It is probably explained somewhere. In any case I have disabled Windows crash reporting in ChimeraX ticket #6788 since it was not useful without C++ stack traces. So the behavior of ctypes catching access violations does not appear to be an issue for ChimeraX. If an access violation from ctypes resulted from a typed command or GUI interaction I think the user would see on OSError with a Report a Bug... button. Opening a script that produces such an error does not offer the Report a Bug... button. That is unfortunate but OSErrors are usually file system permissions or file not found and we don't want those reported. We could our code that catches OSError or a script to look for "access violation" but I guess it is a rare case since I cannot ever recall a bug report (from hand interaction) with that error.

[Tom Goddard]

I don't think there is anything to be done about ctypes catching access violations on Windows unless we want to reinstate Windows crash reporting in the future.