automatically generate safe fallback filename

src/Symfony/Component/HttpFoundation/BinaryFileResponse.php

@@ -160,6 +160,20 @@ class BinaryFileResponse extends Response
             $filename = $this->file->getFilename();
         }
 
+        if ('' === $filenameFallback && (!preg_match('/^[\x20-\x7e]*$/', $filename) || false !== strpos($filename, '%'))) {
+            $encoding = mb_detect_encoding($filename, null, true);
+
+            for ($i = 0; $i < mb_strlen($filename, $encoding); ++$i) {
+                $char = mb_substr($filename, $i, 1, $encoding);
+
+                if ('%' === $char || ord($char) < 32 || ord($char) > 126) {
+                    $filenameFallback .= '_';
+                } else {
+                    $filenameFallback .= $char;
+                }
+            }
+        }
+
         $dispositionHeader = $this->headers->makeDisposition($disposition, $filename, $filenameFallback);
         $this->headers->set('Content-Disposition', $dispositionHeader);
 

src/Symfony/Component/HttpFoundation/Tests/BinaryFileResponseTest.php

@@ -34,6 +34,11 @@ class BinaryFileResponseTest extends ResponseTestCase
         $this->assertEquals('inline; filename="README.md"', $response->headers->get('Content-Disposition'));
     }
 
+    public function testConstructWithNonAsciiFilename()
+    {
+        new BinaryFileResponse(__DIR__.'/Fixtures/föö.html', 200, array(), true, 'attachment');
+    }
+
     /**
      * @expectedException \LogicException
      */
@@ -49,6 +54,14 @@ class BinaryFileResponseTest extends ResponseTestCase
         $this->assertFalse($response->getContent());
     }
 
+    public function testSetContentDispositionGeneratesSafeFallbackFilename()
+    {
+        $response = new BinaryFileResponse(__FILE__);
+        $response->setContentDisposition(ResponseHeaderBag::DISPOSITION_ATTACHMENT, 'föö.html');
+
+        $this->assertSame('attachment; filename="f__.html"; filename*=utf-8\'\'f%C3%B6%C3%B6.html', $response->headers->get('Content-Disposition'));
+    }
+
     /**
      * @dataProvider provideRanges
      */