Add guards for closed file before fopen, fwrite, fread, fclose. Closes …

…#595

src/Mike42/Escpos/PrintConnectors/FilePrintConnector.php

@@ -50,15 +50,20 @@ public function __destruct()
      */
     public function finalize()
     {
-        fclose($this -> fp);
-        $this -> fp = false;
+        if ($this -> fp !== false) {
+            fclose($this -> fp);
+            $this -> fp = false;
+        }
     }
 
     /* (non-PHPdoc)
      * @see PrintConnector::read()
      */
     public function read($len)
     {
+        if ($this -> fp === false) {
+            throw new Exception("PrintConnector has been closed, cannot read input.");
+        }
         return fread($this -> fp, $len);
     }
 
@@ -69,6 +74,9 @@ public function read($len)
      */
     public function write($data)
     {
+        if ($this -> fp === false) {
+            throw new Exception("PrintConnector has been closed, cannot send output.");
+        }
         fwrite($this -> fp, $data);
     }
 }

test/unit/FilePrintConnectorTest.php

@@ -0,0 +1,29 @@
+<?php
+use Mike42\Escpos\PrintConnectors\FilePrintConnector;
+
+class FilePrintConnectorTest extends PHPUnit_Framework_TestCase
+{
+    public function testTmpfile()
+    {
+        // Should attempt to send data to the local printer by writing to it
+        $tmpfname = tempnam("/tmp", "php");
+        $connector = new FilePrintConnector($tmpfname);
+        $connector -> finalize();
+        $connector -> finalize(); // Silently do nothing if printer already closed
+        unlink($tmpfname);
+    }
+
+    public function testReadAfterClose()
+    {
+        // Should attempt to send data to the local printer by writing to it
+        $this -> setExpectedException('Exception');
+        $tmpfname = tempnam("/tmp", "php");
+        try {
+            $connector = new FilePrintConnector($tmpfname);
+            $connector -> finalize();
+            $connector -> write("Test");
+        } finally {
+            unlink($tmpfname);
+        }
+    }
+}