src: fix reader disconnection logic

- A reader disconnection can't be detected by SCardGetStatusChange in the reader
  (cardreader.cpp) but by detecting that the reader doesn't appear in the list of
  readers retrieved in pcsclite.cpp.
- The list of readers is now stored in an object where the keys are the names of
  the readers. When a reader disconnection is detected, the reader is closed
  triggering the 'end' event. Then the reader is removed from the readers list.

lib/pcsclite.js

@@ -20,9 +20,18 @@ var parse_readers_string = function(readers_str) {
     return readers;
 };
 
+/*
+ * It returns an array with the elements contained in a that aren't contained in b
+ */
+function diff(a, b) {
+    return a.filter(function(i) {
+        return b.indexOf(i) === -1;
+    });
+};
+
 module.exports = function() {
 
-    var readers = [];
+    var readers = {};
     var p = new PCSCLite();
     process.nextTick(function() {
         p.start(function(err, data) {
@@ -32,19 +41,13 @@ module.exports = function() {
 
             var names = parse_readers_string(data);
 
-            var new_names = readers.length === 0 ? names : names.filter(function(name) {
-                return readers.every(function(reader) {
-                    return reader.name !== name;
-                });
-            });
-
-            readers = readers.filter(function(reader) {
-                return names.indexOf(reader.name) !== -1;
-            });
+            var current_names = Object.keys(readers);
+            var new_names = diff(names, current_names);
+            var removed_names = diff(current_names, names);
 
             new_names.forEach(function(name) {
                 var r = new CardReader(name);
-                readers.push(r);
+                readers[name] = r;
                 r.get_status(function(err, state, atr) {
                     if (err) {
                         return r.emit('error', err);
@@ -62,10 +65,15 @@ module.exports = function() {
                 r.on('_end', function() {
                     r.removeAllListeners('status');
                     r.emit('end');
+                    delete readers[name];
                 });
 
                 p.emit('reader', r);
             });
+
+            removed_names.forEach(function(name) {
+                readers[name].close();
+            });
         });
     });
 

src/cardreader.cpp

@@ -383,10 +383,7 @@ void CardReader::HandlerFunction(void* arg) {
     while (keep_watching) {
 
         result = SCardGetStatusChange(reader->m_status_card_context, INFINITE, &card_reader_state, 1);
-        keep_watching = ((result == SCARD_S_SUCCESS) &&
-                         (!reader->m_state) &&
-                         (!((card_reader_state.dwEventState & SCARD_STATE_UNKNOWN) ||
-                         (card_reader_state.dwEventState & SCARD_STATE_UNAVAILABLE))));
+        keep_watching = (result == SCARD_S_SUCCESS) && (!reader->m_state);
 
         uv_mutex_lock(&reader->m_mutex);
         if (reader->m_state == 1) {