Fix SCARD_E_SERVICE_STOPPED from SCardListReaders

[Goblenus]

OS: Windows 10 Pro (10.0.17134)
Reader (tested on): Athena ASEDrive V3CR, ARDS JaCarta, Aladdin R.D. JaCarta3
Python version: 3.7
pyscard version: 1.9.7

Behavior:

1. Plug reader to PC (only one!)
2. Start python interpreter
3. Execute

   >>> from smartcard.System import readers

4. Unplug reader
5. Plug reader
6. Execute

   >>> readers()
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
     File "C:\Program Files\Python37\lib\site-packages\smartcard\System.py", line 42, in readers
       return smartcard.reader.ReaderFactory.ReaderFactory.readers(groups)
     File "C:\Program Files\Python37\lib\site-packages\smartcard\reader\ReaderFactory.py", line 58, in readers
       zreaders += fm(groups)
     File "C:\Program Files\Python37\lib\site-packages\smartcard\pcsc\PCSCReader.py", line 110, in readers
       for reader in __PCSCreaders__(hcontext, groups):
     File "C:\Program Files\Python37\lib\site-packages\smartcard\pcsc\PCSCReader.py", line 49, in __PCSCreaders__
       raise ListReadersException(hresult)
   smartcard.pcsc.PCSCExceptions.ListReadersException: 'Failure to list readers: Диспетчер ресурсов смарт-карт завершил работу. '

How it was fixed:

1. Check for SCARD_E_SERVICE_STOPPED from SCardListReaders
2. Raise CardServiceStoppedException
3. Establish new context for PCSCContext

[coveralls]

Coverage increased (+0.002%) to 24.666% when pulling 4b9363f on Goblenus:master into a31fba3 on LudovicRousseau:master.

[LudovicRousseau]

Your patch is nice but not complete.

1. start python (I use Python 3.6.5 (v3.6.5:f59c0932b4, Mar 28 2018, 17:00:18) [MSC v.1900 64 bit (AMD64)] on win32)
2. Execute

>>> from smartcard.System import readers
>>> readers()
[]

3. plug a reader
4. Execute

>>> readers()
['reader name']

5. unplug the reader
6. Execute

>>> readers()
Failed to SCardFreeMemory!
Traceback (most recent call last):
  File "C:\Users\Ludovic\AppData\Local\Programs\Python\Python36\lib\site-packages\smartcard\pcsc\PCSCReader.py", line 113, in readers
    pcsc_readers = __PCSCreaders__(hcontext, groups)
  File "C:\Users\Ludovic\AppData\Local\Programs\Python\Python36\lib\site-packages\smartcard\pcsc\PCSCReader.py", line 49, in __PCSCreaders__
    raise CardServiceStoppedException()
smartcard.Exceptions.CardServiceStoppedException

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Users\Ludovic\AppData\Local\Programs\Python\Python36\lib\site-packages\smartcard\System.py", line 42, in readers
    return smartcard.reader.ReaderFactory.ReaderFactory.readers(groups)
  File "C:\Users\Ludovic\AppData\Local\Programs\Python\Python36\lib\site-packages\smartcard\reader\ReaderFactory.py", line 58, in readers
    zreaders += fm(groups)
  File "C:\Users\Ludovic\AppData\Local\Programs\Python\Python36\lib\site-packages\smartcard\pcsc\PCSCReader.py", line 116, in readers
    pcsc_readers = __PCSCreaders__(hcontext, groups)
  File "C:\Users\Ludovic\AppData\Local\Programs\Python\Python36\lib\site-packages\smartcard\pcsc\PCSCReader.py", line 44, in __PCSCreaders__
    hresult, readers = SCardListReaders(hcontext, groups)
  File "C:\Users\Ludovic\AppData\Local\Programs\Python\Python36\lib\site-packages\smartcard\scard\scard.py", line 1067, in SCardListReaders
    return _scard.SCardListReaders(hcontext, readergroups)
TypeError: Expected a python long as SCARDCONTEXT.
>>>

Can you fix that?
Thanks.

[Goblenus]

It seems I forget to "getContext()" from "PCSCContext.establish_new_context()".

I'll check it on Monday. Is it ok?

[LudovicRousseau]

OK for me. Take your time to provide a correct patch.

[LudovicRousseau]

The problem is that your new method releaseContext() must create a new PC/SC context. Or getContext() will return a now invalid context.
__PCSCContextSingleton is no more really a singleton.

I propose to rename establish_new_context() in renewContext()

[Goblenus]

Ok. I done it.

Now I think this is not the best way how I have fixed it, I need some time to think. But it works nice and you can merge it.

[LudovicRousseau]

Merged in bf906d3

Thanks