Fixed #30509 -- Made FileResponse better handle buffers and non-zero file offsets.

tests/responses/test_fileresponse.py

@@ -18,17 +18,71 @@ class UnseekableBytesIO(io.BytesIO):
 class FileResponseTests(SimpleTestCase):
     def test_content_length_file(self):
         response = FileResponse(open(__file__, 'rb'))
-        self.assertEqual(response.headers['Content-Length'], str(os.path.getsize(__file__)))
         response.close()
+        self.assertEqual(response.headers['Content-Length'], str(os.path.getsize(__file__)))
 
     def test_content_length_buffer(self):
         response = FileResponse(io.BytesIO(b'binary content'))
         self.assertEqual(response.headers['Content-Length'], '14')
 
+    def test_content_length_nonzero_starting_position_file(self):
+        file = open(__file__, 'rb')
+        file.seek(10)
+        response = FileResponse(file)
+        response.close()
+        self.assertEqual(response.headers['Content-Length'], str(os.path.getsize(__file__) - 10))
+
+    def test_content_length_nonzero_starting_position_buffer(self):
+        test_tuples = (
+            ('BytesIO', io.BytesIO),
+            ('UnseekableBytesIO', UnseekableBytesIO),
+        )
+        for buffer_class_name, BufferClass in test_tuples:
+            with self.subTest(buffer_class_name=buffer_class_name):
+                buffer = BufferClass(b'binary content')
+                buffer.seek(10)
+                response = FileResponse(buffer)
+                self.assertEqual(response.headers['Content-Length'], '4')
+
+    def test_content_length_nonzero_starting_position_file_seekable_no_tell(self):
+        class TestFile:
+            def __init__(self, path, *args, **kwargs):
+                self._file = open(path, *args, **kwargs)
+
+            def read(self, n_bytes=-1):
+                return self._file.read(n_bytes)
+
+            def seek(self, offset, whence=io.SEEK_SET):
+                return self._file.seek(offset, whence)
+
+            def seekable(self):
+                return True
+
+            @property
+            def name(self):
+                return self._file.name
+
+            def close(self):
+                if self._file:
+                    self._file.close()
+                    self._file = None
+
+            def __enter__(self):
+                return self
+
+            def __exit__(self, e_type, e_val, e_tb):
+                self.close()
+
+        file = TestFile(__file__, 'rb')
+        file.seek(10)
+        response = FileResponse(file)
+        response.close()
+        self.assertEqual(response.headers['Content-Length'], str(os.path.getsize(__file__) - 10))
+
     def test_content_type_file(self):
         response = FileResponse(open(__file__, 'rb'))
-        self.assertIn(response.headers['Content-Type'], ['text/x-python', 'text/plain'])
         response.close()
+        self.assertIn(response.headers['Content-Type'], ['text/x-python', 'text/plain'])
 
     def test_content_type_buffer(self):
         response = FileResponse(io.BytesIO(b'binary content'))
@@ -38,8 +92,14 @@ class FileResponseTests(SimpleTestCase):
         response = FileResponse(io.BytesIO(b'binary content'), content_type='video/webm')
         self.assertEqual(response.headers['Content-Type'], 'video/webm')
 
+    def test_content_type_buffer_explicit_default(self):
+        response = FileResponse(io.BytesIO(b'binary content'), content_type='text/html')
+        self.assertEqual(response.headers['Content-Type'], 'text/html')
+
     def test_content_type_buffer_named(self):
         test_tuples = (
+            (__file__, ['text/x-python', 'text/plain']),
+            (__file__ + 'nosuchfile', ['application/octet-stream']),
             ('test_fileresponse.py', ['text/x-python', 'text/plain']),
             ('test_fileresponse.pynosuchfile', ['application/octet-stream']),
         )
@@ -59,15 +119,16 @@ class FileResponseTests(SimpleTestCase):
             (False, 'inline'),
             (True, 'attachment'),
         )
-        for (filename, header_filename), (as_attachment, header_disposition)\
-                in itertools.product(filenames, dispositions):
+        for (filename, header_filename), (as_attachment, header_disposition) in itertools.product(
+            filenames, dispositions
+        ):
             with self.subTest(filename=filename, disposition=header_disposition):
                 response = FileResponse(open(__file__, 'rb'), filename=filename, as_attachment=as_attachment)
+                response.close()
                 self.assertEqual(
                     response.headers['Content-Disposition'],
                     '%s; filename="%s"' % (header_disposition, header_filename),
                 )
-                response.close()
 
     def test_content_disposition_buffer(self):
         response = FileResponse(io.BytesIO(b'binary content'))
@@ -89,7 +150,7 @@ class FileResponseTests(SimpleTestCase):
                 filename='custom_name.py',
             )
             self.assertEqual(
-                response.headers['Content-Disposition'], '%s; filename="custom_name.py"' % header_disposition
+                response.headers['Content-Disposition'], '%s; filename="custom_name.py"' % header_disposition,
             )
 
     def test_response_buffer(self):
@@ -108,6 +169,15 @@ class FileResponseTests(SimpleTestCase):
                 response = FileResponse(buffer)
                 self.assertEqual(list(response), [b'tent'])
 
+    def test_buffer_explicit_absolute_filename(self):
+        """
+        Headers are set correctly with a buffer when an absolute filename is
+        provided.
+        """
+        response = FileResponse(io.BytesIO(b'binary content'), filename=__file__)
+        self.assertEqual(response.headers['Content-Length'], '14')
+        self.assertEqual(response.headers['Content-Disposition'], 'inline; filename="test_fileresponse.py"')
+
     @skipIf(sys.platform == 'win32', "Named pipes are Unix-only.")
     def test_file_from_named_pipe_response(self):
         with tempfile.TemporaryDirectory() as temp_dir: