src: fix readers detection logic

- Also, upgrade buffertools that allows to use it only when needed.

lib/pcsclite.js

@@ -1,5 +1,5 @@
 var events = require('events');
-require('buffertools');
+var bt = require('buffertools');
 
 /* Make sure we choose the correct build directory */
 var bindings = require('bindings')('pcsclite');
@@ -12,7 +12,7 @@ var parse_readers_string = function(readers_str) {
     var pos;
     var readers = [];
     var ini = 0;
-    while ((pos = readers_str.slice(ini).indexOf('\0')) > 0) {
+    while ((pos = bt.indexOf(readers_str.slice(ini), '\0')) > 0) {
         readers.push(readers_str.slice(ini, ini + pos).toString());
         ini += pos + 1;
     }
@@ -30,17 +30,21 @@ module.exports = function() {
                 return p.emit('error', err);
             }
 
-            var readers_aux = [];
             var names = parse_readers_string(data);
-            var new_names = names.filter(function(name) {
+
-                return !readers.some(function(reader) {
+            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;
+            });
+
             new_names.forEach(function(name) {
                 var r = new CardReader(name);
-                readers_aux.push(r);
+                readers.push(r);
                 r.get_status(function(err, state, atr) {
                     if (err) {
                         return r.emit('error', e);
@@ -57,8 +61,6 @@ module.exports = function() {
 
                 p.emit('reader', r);
             });
-
-            readers = readers_aux;
         });
     });
 

package.json

@@ -10,7 +10,7 @@
         "test": "test"
     },
     "dependencies": {
-        "buffertools": "~1.1.1",
+        "buffertools": "^2.1.2",
         "bindings": "~1.1.0"
     },
     "devDependencies": {