1"""PCSC context singleton.
2
3__author__ = "http://www.gemalto.com"
4
5Copyright 2001-2012 gemalto
6Author: Jean-Daniel Aussel, mailto:jean-daniel.aussel@gemalto.com
7
8This file is part of pyscard.
9
10pyscard is free software; you can redistribute it and/or modify
11it under the terms of the GNU Lesser General Public License as published by
12the Free Software Foundation; either version 2.1 of the License, or
13(at your option) any later version.
14
15pyscard is distributed in the hope that it will be useful,
16but WITHOUT ANY WARRANTY; without even the implied warranty of
17MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18GNU Lesser General Public License for more details.
19
20You should have received a copy of the GNU Lesser General Public License
21along with pyscard; if not, write to the Free Software
22Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
23"""
24
25from threading import RLock
26
27from smartcard.scard import *
28from smartcard.pcsc.PCSCExceptions import EstablishContextException
29
30
31class PCSCContext(object):
32    """Manage a singleton pcsc context handle."""
33
34    class __PCSCContextSingleton:
35        """The actual pcsc context class as a singleton."""
36
37        def __init__(self):
38            hresult, self.hcontext = SCardEstablishContext(SCARD_SCOPE_USER)
39            if hresult != 0:
40                raise EstablishContextException(hresult)
41
42        def getContext(self):
43            return self.hcontext
44
45        def releaseContext(self):
46            return SCardReleaseContext(self.hcontext)
47
48    # the singleton
49    mutex = RLock()
50    instance = None
51
52    def __init__(self):
53        PCSCContext.mutex.acquire()
54        try:
55            if not PCSCContext.instance:
56                self.renewContext()
57        finally:
58            PCSCContext.mutex.release()
59
60    def __getattr__(self, name):
61        if self.instance:
62            return getattr(self.instance, name)
63
64    def renewContext():
65        PCSCContext.mutex.acquire()
66        try:
67            if PCSCContext.instance is not None:
68                PCSCContext.instance.releaseContext()
69
70            PCSCContext.instance = PCSCContext.__PCSCContextSingleton()
71        finally:
72            PCSCContext.mutex.release()
73
74        return PCSCContext.instance.getContext()
75    renewContext = staticmethod(renewContext)
76