Fixed Improper Method Call: Modified __exit__()

[fazledyn-or]

Details

While triaging your project, our bug fixing tool generated the following message(s)-

In file: ocrd_mets.py, class: OcrdMets, there is a special method __exit__ that contains an unexpected number of parameters. Each call to this method will result in a TypeError. iCR suggested that special methods should have an expected number of parameters. More infomation can be found in the Python documentation on the various special method.

Proof of Concept

Executing the test code -

from ocrd_models.ocrd_mets import OcrdMets

print("Before context")
with OcrdMets(content='<mets></mets>') as mets:
    print(mets.__class__)
print("After context")

Gives the output -

(env) ataf@openrefactory:~/BFAS/Source/core$ python3 _test.py 
Before context
Traceback (most recent call last):
  File "_test.py", line 4, in <module>
    with OcrdMets(content='<mets></mets>') as mets:
AttributeError: __enter__

The error is due to the class OcrdMets not having the __enter__ method. After implementing the method like below -

def __enter__(self):
    pass

And executing the following script gives us a different output.

(env) ataf@openrefactory:~/BFAS/Source/core$ python3 _test.py 
Before context
<class 'NoneType'>
Traceback (most recent call last):
  File "_test.py", line 5, in <module>
    print(mets.__class__)
TypeError: __exit__() takes 1 positional argument but 4 were given

This is because the __exit__ method expects 4 arguments (self, exc_type, exc_value, traveback) according to the the documentation. After modifying the __exit__ method and executing the script again results in sucess.

Changes

• Added a new method called __enter__
• Modified the __exit__ method to overcome TypeError

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Sponsorship and Support

This work is done by the security researchers from OpenRefactory and is supported by the Open Source Security Foundation (OpenSSF): Project Alpha-Omega. Alpha-Omega is a project partnering with open source software project maintainers to systematically find new, as-yet-undiscovered vulnerabilities in open source code - and get them fixed – to improve global software supply chain security.

The bug is found by running the Intelligent Code Repair (iCR) tool by OpenRefactory and then manually triaging the results.

[kba]

Thanks for the PR, we removed the unused __exit__ method in #1132 .