diff --git a/Lib/codecs.py b/Lib/codecs.py index 21c45a7d10a..7f23e9775df 100644 --- a/Lib/codecs.py +++ b/Lib/codecs.py @@ -905,11 +905,16 @@ def open(filename, mode='r', encoding=None, errors='strict', buffering=-1): file = builtins.open(filename, mode, buffering) if encoding is None: return file - info = lookup(encoding) - srw = StreamReaderWriter(file, info.streamreader, info.streamwriter, errors) - # Add attributes to simplify introspection - srw.encoding = encoding - return srw + + try: + info = lookup(encoding) + srw = StreamReaderWriter(file, info.streamreader, info.streamwriter, errors) + # Add attributes to simplify introspection + srw.encoding = encoding + return srw + except: + file.close() + raise def EncodedFile(file, data_encoding, file_encoding=None, errors='strict'): diff --git a/Lib/test/test_codecs.py b/Lib/test/test_codecs.py index 8d9cb908903..dcdd574bc7f 100644 --- a/Lib/test/test_codecs.py +++ b/Lib/test/test_codecs.py @@ -1154,6 +1154,7 @@ class UTF8SigTest(UTF8Test, unittest.TestCase): got = ostream.getvalue() self.assertEqual(got, unistring) + class EscapeDecodeTest(unittest.TestCase): def test_empty(self): self.assertEqual(codecs.escape_decode(b""), (b"", 0)) @@ -1725,6 +1726,14 @@ class CodecsModuleTest(unittest.TestCase): self.assertRaises(UnicodeError, codecs.decode, b'abc', 'undefined', errors) + def test_file_closes_if_lookup_error_raised(self): + mock_open = mock.mock_open() + with mock.patch('builtins.open', mock_open) as file: + with self.assertRaises(LookupError): + codecs.open(support.TESTFN, 'wt', 'invalid-encoding') + + file().close.assert_called() + class StreamReaderTest(unittest.TestCase): diff --git a/Misc/NEWS.d/next/Library/2019-12-20-16-06-28.bpo-38971.fKRYlF.rst b/Misc/NEWS.d/next/Library/2019-12-20-16-06-28.bpo-38971.fKRYlF.rst new file mode 100644 index 00000000000..9676d72b44a --- /dev/null +++ b/Misc/NEWS.d/next/Library/2019-12-20-16-06-28.bpo-38971.fKRYlF.rst @@ -0,0 +1,3 @@ +Open issue in the BPO indicated a desire to make the implementation of +codecs.open() at parity with io.open(), which implements a try/except to +assure file stream gets closed before an exception is raised. \ No newline at end of file