new method reset for pcsc connections; refs #29

src/pcsc.hxx

@@ -552,6 +552,27 @@ namespace pcsc {
         
       // }
 
+      /// Reset and reestablish the connection.
+      /** @note You must remove all readers that have been returned by
+                @ref reader(), if you have assigned them to a variable
+                and stored them. Otherwise the connections will remain
+                open and next access should probably fail.
+          @begincode
+          {
+            mrw::Shared<Reader> r(c.reader(name));
+            // use r
+            c.reset(); // now r is invalid
+            // either reassign r:
+            r = c.reader(name);
+            // or simply reset it
+            r.reset();
+          }
+          // or clenaup by leaving the context of r
+          @endcode */
+      void reset() {
+        _connectionlifetime->reset();
+      }
+      
       //! Find all readers with a given ATR.
       /*! @param atr full or partial ATR to match to the reader's ATR
           @returns list of readers that contain @c atr in their ATR */
@@ -630,7 +651,7 @@ namespace pcsc {
         public:
           //! opens connection that is closed on destruction
           ConnectionLifetime(Scope s, bool exc):
-              _exc(exc), _id(0),
+              _exc(exc), _id(0), _s(s),
               _state(SCardEstablishContext(s, 0, 0, &_id)) {
             CRYPTOLOG("Open Connection");
             check("establish smartcard context");
@@ -1064,10 +1085,20 @@ namespace pcsc {
             return _readers.find(name)->second;
           }
 
+          /// Cleans up the readers, resets the context.
+          void reset() {
+            _readers.clear();
+            _state = SCardReleaseContext(_id);
+            check("smartcard release context");
+            _state = SCardEstablishContext(_s, 0, 0, &_id);
+            check("establish smartcard context");
+          }
+
         private:
 
           bool _exc;
           SCARDCONTEXT _id;
+          Scope _s;
           long _state;
       
           //! Readers are closed when the last shared object is destructed