Description

exgurd provides a decorator to guard a function or method against exceptions. This is useful in situations where untrusted code is executed, e.g. when executing a third-party module in a framework.

In comparison to the suppress context manager from Python 3, exguard provides more means to control exception handling:

• filter on modules and namespaces to define which exceptions to catch and leave exceptions in other code untouched

• execute a callback function once an exception was caught

• execute a callback function in the finally block

For example, an API method in a web application that calls through to code in third-party modules can be guarded against exceptions in this modules only, while having exceptions in the framework itself be raised verbatim:

from exguard import guard, traceback_str

def throw_to_client(exception, module):
    tb = traceback_str(exception)

    # Do something to pass a traceback to the browser, disable the plugin,…
    pass

# All third-party modules are under one namespace
@guard(modules=["myframework.plugins"], submodules=True, fullstack=True, cb_except=throw_to_client)
def call_plugin_api():
    # An exception inside this will be caught
    myframework.plugins.evil.crash()

    # This will still raise an exception like normal
    x = 17 / 0

Authors

exguard has been started as a part of Veripeditus, mainly by Eike Tim Jesinghaus <eike@naturalnet.de>.

Licence and copyright

exguard - Guard code against exceptions, e.g. for running untrusted module code in a framework
Copyright (C) 2017  Eike Tim Jesinghaus <eike@naturalnet.de>

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

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