vfs_littlefs_file.c: Prevent double close of a file

[robert-hh]

An attempt to close a file twice resulted in a crash, because buffers should have been freed again. This change checks first, if a file is already closed.

[peter-pycom]

https://github.com/pycom/pycom-micropython-sigfox/issues/523

[geza-pycom]

Hello! Good catch, it was hard to decode because without removing the _m_del_obj(pyb_file_objt, self) call the exception is dropped by _mp_load_methodmaybe(). I checked your example the issue happens and your fix solves it.

However with the following example, without your fix, the problem does not come alive: `

f = open("myfile.txt", "w") f.write("ssss") 4 f.close() f.close() Traceback (most recent call last): File "", line 1, in AttributeError: 'function' object has no attribute 'close' `

I think here the exception is correct, because the file object ("f") is deleted by _m_del_obj(pyb_file_objt, self).

It would be interesting to see why the crash happens with your example and why it does not with this other example.

[robert-hh]

I'm a little bit reluctant to delete python objects deep inside drivers, unless you know that they are not used any more. When I wrote that, I had a clear opinion why it was wrong here, but now I do not know it any more. Anyhow, it does not to keep it and let the garbage collector do the job later.

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[geza-pycom]

Thanks, this fix looks good !

[robert-hh]

Fixed in 1.20.3.b3