use send for child process

src/password.js

@@ -4,34 +4,28 @@
 	var fork = require('child_process').fork;
 
 	module.hash = function(rounds, password, callback) {
-		var child = fork('./bcrypt', ['hash', rounds, password], {
-				silent: true
-			}),
-			response = '';
-
-		child.stdout.on('data', function(chunk) {
-			response += chunk.toString();
-		});
-
-		child.stdout.on('end', function() {
-			callback(null, response);
-		});
+		forkChild({type: 'hash', rounds: rounds, password: password}, callback);
 	};
 
 	module.compare = function(password, hash, callback) {
-		var child = fork('./bcrypt', ['compare', password, hash], {
-				silent: true
-			}),
-			response = '';
-
-		child.stdout.on('data', function(chunk) {
-			response += chunk.toString();
-		});
-
-		child.stdout.on('end', function() {
-			callback(null, response === 'true');
-		});
+		forkChild({type: 'compare', password: password, hash: hash}, callback);
 	};
 
+	function forkChild(message, callback) {
+		var child = fork('./bcrypt', {
+				silent: true
+			});
+
+		child.on('message', function(msg) {
+			if (msg.err) {
+				return callback(new Error(msg.err));
+			}
+
+			callback(null, msg.result);
+		});
+
+		child.send(message);
+	}
+
 	return module;
 })(exports);