[HttpFoundation] Avoid mime type guess with temp files in BinaryFileResponse

Author: alexandre-daubois

BinaryFileResponse.php

@@ -189,7 +189,12 @@ public function prepare(Request $request): static
         }
 
         if (!$this->headers->has('Content-Type')) {
-            $this->headers->set('Content-Type', $this->file->getMimeType() ?: 'application/octet-stream');
+            $mimeType = null;
+            if (!$this->tempFileObject) {
+                $mimeType = $this->file->getMimeType();
+            }
+
+            $this->headers->set('Content-Type', $mimeType ?: 'application/octet-stream');
         }
 
         parent::prepare($request);

Tests/BinaryFileResponseTest.php

@@ -458,4 +458,15 @@ public function testCreateFromTemporaryFile()
         $string = ob_get_clean();
         $this->assertSame('foo,bar', $string);
     }
+
+    public function testCreateFromTemporaryFileWithoutMimeType()
+    {
+        $file = new \SplTempFileObject();
+        $file->fwrite('foo,bar');
+
+        $response = new BinaryFileResponse($file);
+        $response->prepare(new Request());
+
+        $this->assertSame('application/octet-stream', $response->headers->get('Content-Type'));
+    }
 }