#8271: the utf-8 decoder now outputs the correct number of U+FFFD characters when used with the "replace" error handler on invalid utf-8 sequences. Patch by Serhiy Storchaka, tests by Ezio Melotti.

1 files changed, 221 insertions, 1 deletions

diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py
index 46c98bd..a811c4c 100644
--- a/Lib/test/test_unicode.py
+++ b/Lib/test/test_unicode.py
@@ -1349,7 +1349,7 @@ class UnicodeTest(string_tests.CommonTest,
             # with start byte of a 2-byte sequence
             (b'\xc2', FFFD), # only the start byte
             (b'\xc2\xc2', FFFD*2), # 2 start bytes
-            (b'\xc2\xc2\xc2', FFFD*3), # 2 start bytes
+            (b'\xc2\xc2\xc2', FFFD*3), # 3 start bytes
             (b'\xc2\x41', FFFD+'A'), # invalid continuation byte
             # with start byte of a 3-byte sequence
             (b'\xe1', FFFD), # only the start byte
@@ -1419,6 +1419,226 @@ class UnicodeTest(string_tests.CommonTest,
             self.assertEqual(seq.decode('utf-8', 'ignore'),
                              res.replace('\uFFFD', ''))
 
+    def to_bytestring(self, seq):
+        return bytes(int(c, 16) for c in seq.split())
+
+    def assertCorrectUTF8Decoding(self, seq, res, err):
+        """
+        Check that an invalid UTF-8 sequence raises an UnicodeDecodeError when
+        'strict' is used, returns res when 'replace' is used, and that doesn't
+        return anything when 'ignore' is used.
+        """
+        with self.assertRaises(UnicodeDecodeError) as cm:
+            seq.decode('utf-8')
+        exc = cm.exception
+
+        self.assertIn(err, str(exc))
+        self.assertEqual(seq.decode('utf-8', 'replace'), res)
+        self.assertEqual((b'aaaa' + seq + b'bbbb').decode('utf-8', 'replace'),
+                         'aaaa' + res + 'bbbb')
+        res = res.replace('\ufffd', '')
+        self.assertEqual(seq.decode('utf-8', 'ignore'), res)
+        self.assertEqual((b'aaaa' + seq + b'bbbb').decode('utf-8', 'ignore'),
+                          'aaaa' + res + 'bbbb')
+
+    def test_invalid_start_byte(self):
+        """
+        Test that an 'invalid start byte' error is raised when the first byte
+        is not in the ASCII range or is not a valid start byte of a 2-, 3-, or
+        4-bytes sequence. The invalid start byte is replaced with a single
+        U+FFFD when errors='replace'.
+        E.g. <80> is a continuation byte and can appear only after a start byte.
+        """
+        FFFD = '\ufffd'
+        for byte in b'\x80\xA0\x9F\xBF\xC0\xC1\xF5\xFF':
+            self.assertCorrectUTF8Decoding(bytes([byte]), '\ufffd',
+                                           'invalid start byte')
+
+    def test_unexpected_end_of_data(self):
+        """
+        Test that an 'unexpected end of data' error is raised when the string
+        ends after a start byte of a 2-, 3-, or 4-bytes sequence without having
+        enough continuation bytes.  The incomplete sequence is replaced with a
+        single U+FFFD when errors='replace'.
+        E.g. in the sequence <F3 80 80>, F3 is the start byte of a 4-bytes
+        sequence, but it's followed by only 2 valid continuation bytes and the
+        last continuation bytes is missing.
+        Note: the continuation bytes must be all valid, if one of them is
+        invalid another error will be raised.
+        """
+        sequences = [
+            'C2', 'DF',
+            'E0 A0', 'E0 BF', 'E1 80', 'E1 BF', 'EC 80', 'EC BF',
+            'ED 80', 'ED 9F', 'EE 80', 'EE BF', 'EF 80', 'EF BF',
+            'F0 90', 'F0 BF', 'F0 90 80', 'F0 90 BF', 'F0 BF 80', 'F0 BF BF',
+            'F1 80', 'F1 BF', 'F1 80 80', 'F1 80 BF', 'F1 BF 80', 'F1 BF BF',
+            'F3 80', 'F3 BF', 'F3 80 80', 'F3 80 BF', 'F3 BF 80', 'F3 BF BF',
+            'F4 80', 'F4 8F', 'F4 80 80', 'F4 80 BF', 'F4 8F 80', 'F4 8F BF'
+        ]
+        FFFD = '\ufffd'
+        for seq in sequences:
+            self.assertCorrectUTF8Decoding(self.to_bytestring(seq), '\ufffd',
+                                           'unexpected end of data')
+
+    def test_invalid_cb_for_2bytes_seq(self):
+        """
+        Test that an 'invalid continuation byte' error is raised when the
+        continuation byte of a 2-bytes sequence is invalid.  The start byte
+        is replaced by a single U+FFFD and the second byte is handled
+        separately when errors='replace'.
+        E.g. in the sequence <C2 41>, C2 is the start byte of a 2-bytes
+        sequence, but 41 is not a valid continuation byte because it's the
+        ASCII letter 'A'.
+        """
+        FFFD = '\ufffd'
+        FFFDx2 = FFFD * 2
+        sequences = [
+            ('C2 00', FFFD+'\x00'), ('C2 7F', FFFD+'\x7f'),
+            ('C2 C0', FFFDx2), ('C2 FF', FFFDx2),
+            ('DF 00', FFFD+'\x00'), ('DF 7F', FFFD+'\x7f'),
+            ('DF C0', FFFDx2), ('DF FF', FFFDx2),
+        ]
+        for seq, res in sequences:
+            self.assertCorrectUTF8Decoding(self.to_bytestring(seq), res,
+                                           'invalid continuation byte')
+
+    def test_invalid_cb_for_3bytes_seq(self):
+        """
+        Test that an 'invalid continuation byte' error is raised when the
+        continuation byte(s) of a 3-bytes sequence are invalid.  When
+        errors='replace', if the first continuation byte is valid, the first
+        two bytes (start byte + 1st cb) are replaced by a single U+FFFD and the
+        third byte is handled separately, otherwise only the start byte is
+        replaced with a U+FFFD and the other continuation bytes are handled
+        separately.
+        E.g. in the sequence <E1 80 41>, E1 is the start byte of a 3-bytes
+        sequence, 80 is a valid continuation byte, but 41 is not a valid cb
+        because it's the ASCII letter 'A'.
+        Note: when the start byte is E0 or ED, the valid ranges for the first
+        continuation byte are limited to A0..BF and 80..9F respectively.
+        Python 2 used to consider all the bytes in range 80..BF valid when the
+        start byte was ED.  This is fixed in Python 3.
+        """
+        FFFD = '\ufffd'
+        FFFDx2 = FFFD * 2
+        sequences = [
+            ('E0 00', FFFD+'\x00'), ('E0 7F', FFFD+'\x7f'), ('E0 80', FFFDx2),
+            ('E0 9F', FFFDx2), ('E0 C0', FFFDx2), ('E0 FF', FFFDx2),
+            ('E0 A0 00', FFFD+'\x00'), ('E0 A0 7F', FFFD+'\x7f'),
+            ('E0 A0 C0', FFFDx2), ('E0 A0 FF', FFFDx2),
+            ('E0 BF 00', FFFD+'\x00'), ('E0 BF 7F', FFFD+'\x7f'),
+            ('E0 BF C0', FFFDx2), ('E0 BF FF', FFFDx2), ('E1 00', FFFD+'\x00'),
+            ('E1 7F', FFFD+'\x7f'), ('E1 C0', FFFDx2), ('E1 FF', FFFDx2),
+            ('E1 80 00', FFFD+'\x00'), ('E1 80 7F', FFFD+'\x7f'),
+            ('E1 80 C0', FFFDx2), ('E1 80 FF', FFFDx2),
+            ('E1 BF 00', FFFD+'\x00'), ('E1 BF 7F', FFFD+'\x7f'),
+            ('E1 BF C0', FFFDx2), ('E1 BF FF', FFFDx2), ('EC 00', FFFD+'\x00'),
+            ('EC 7F', FFFD+'\x7f'), ('EC C0', FFFDx2), ('EC FF', FFFDx2),
+            ('EC 80 00', FFFD+'\x00'), ('EC 80 7F', FFFD+'\x7f'),
+            ('EC 80 C0', FFFDx2), ('EC 80 FF', FFFDx2),
+            ('EC BF 00', FFFD+'\x00'), ('EC BF 7F', FFFD+'\x7f'),
+            ('EC BF C0', FFFDx2), ('EC BF FF', FFFDx2), ('ED 00', FFFD+'\x00'),
+            ('ED 7F', FFFD+'\x7f'),
+            ('ED A0', FFFDx2), ('ED BF', FFFDx2), # see note ^
+            ('ED C0', FFFDx2), ('ED FF', FFFDx2), ('ED 80 00', FFFD+'\x00'),
+            ('ED 80 7F', FFFD+'\x7f'), ('ED 80 C0', FFFDx2),
+            ('ED 80 FF', FFFDx2), ('ED 9F 00', FFFD+'\x00'),
+            ('ED 9F 7F', FFFD+'\x7f'), ('ED 9F C0', FFFDx2),
+            ('ED 9F FF', FFFDx2), ('EE 00', FFFD+'\x00'),
+            ('EE 7F', FFFD+'\x7f'), ('EE C0', FFFDx2), ('EE FF', FFFDx2),
+            ('EE 80 00', FFFD+'\x00'), ('EE 80 7F', FFFD+'\x7f'),
+            ('EE 80 C0', FFFDx2), ('EE 80 FF', FFFDx2),
+            ('EE BF 00', FFFD+'\x00'), ('EE BF 7F', FFFD+'\x7f'),
+            ('EE BF C0', FFFDx2), ('EE BF FF', FFFDx2), ('EF 00', FFFD+'\x00'),
+            ('EF 7F', FFFD+'\x7f'), ('EF C0', FFFDx2), ('EF FF', FFFDx2),
+            ('EF 80 00', FFFD+'\x00'), ('EF 80 7F', FFFD+'\x7f'),
+            ('EF 80 C0', FFFDx2), ('EF 80 FF', FFFDx2),
+            ('EF BF 00', FFFD+'\x00'), ('EF BF 7F', FFFD+'\x7f'),
+            ('EF BF C0', FFFDx2), ('EF BF FF', FFFDx2),
+        ]
+        for seq, res in sequences:
+            self.assertCorrectUTF8Decoding(self.to_bytestring(seq), res,
+                                           'invalid continuation byte')
+
+    def test_invalid_cb_for_4bytes_seq(self):
+        """
+        Test that an 'invalid continuation byte' error is raised when the
+        continuation byte(s) of a 4-bytes sequence are invalid.  When
+        errors='replace',the start byte and all the following valid
+        continuation bytes are replaced with a single U+FFFD, and all the bytes
+        starting from the first invalid continuation bytes (included) are
+        handled separately.
+        E.g. in the sequence <E1 80 41>, E1 is the start byte of a 3-bytes
+        sequence, 80 is a valid continuation byte, but 41 is not a valid cb
+        because it's the ASCII letter 'A'.
+        Note: when the start byte is E0 or ED, the valid ranges for the first
+        continuation byte are limited to A0..BF and 80..9F respectively.
+        However, when the start byte is ED, Python 2 considers all the bytes
+        in range 80..BF valid.  This is fixed in Python 3.
+        """
+        FFFD = '\ufffd'
+        FFFDx2 = FFFD * 2
+        sequences = [
+            ('F0 00', FFFD+'\x00'), ('F0 7F', FFFD+'\x7f'), ('F0 80', FFFDx2),
+            ('F0 8F', FFFDx2), ('F0 C0', FFFDx2), ('F0 FF', FFFDx2),
+            ('F0 90 00', FFFD+'\x00'), ('F0 90 7F', FFFD+'\x7f'),
+            ('F0 90 C0', FFFDx2), ('F0 90 FF', FFFDx2),
+            ('F0 BF 00', FFFD+'\x00'), ('F0 BF 7F', FFFD+'\x7f'),
+            ('F0 BF C0', FFFDx2), ('F0 BF FF', FFFDx2),
+            ('F0 90 80 00', FFFD+'\x00'), ('F0 90 80 7F', FFFD+'\x7f'),
+            ('F0 90 80 C0', FFFDx2), ('F0 90 80 FF', FFFDx2),
+            ('F0 90 BF 00', FFFD+'\x00'), ('F0 90 BF 7F', FFFD+'\x7f'),
+            ('F0 90 BF C0', FFFDx2), ('F0 90 BF FF', FFFDx2),
+            ('F0 BF 80 00', FFFD+'\x00'), ('F0 BF 80 7F', FFFD+'\x7f'),
+            ('F0 BF 80 C0', FFFDx2), ('F0 BF 80 FF', FFFDx2),
+            ('F0 BF BF 00', FFFD+'\x00'), ('F0 BF BF 7F', FFFD+'\x7f'),
+            ('F0 BF BF C0', FFFDx2), ('F0 BF BF FF', FFFDx2),
+            ('F1 00', FFFD+'\x00'), ('F1 7F', FFFD+'\x7f'), ('F1 C0', FFFDx2),
+            ('F1 FF', FFFDx2), ('F1 80 00', FFFD+'\x00'),
+            ('F1 80 7F', FFFD+'\x7f'), ('F1 80 C0', FFFDx2),
+            ('F1 80 FF', FFFDx2), ('F1 BF 00', FFFD+'\x00'),
+            ('F1 BF 7F', FFFD+'\x7f'), ('F1 BF C0', FFFDx2),
+            ('F1 BF FF', FFFDx2), ('F1 80 80 00', FFFD+'\x00'),
+            ('F1 80 80 7F', FFFD+'\x7f'), ('F1 80 80 C0', FFFDx2),
+            ('F1 80 80 FF', FFFDx2), ('F1 80 BF 00', FFFD+'\x00'),
+            ('F1 80 BF 7F', FFFD+'\x7f'), ('F1 80 BF C0', FFFDx2),
+            ('F1 80 BF FF', FFFDx2), ('F1 BF 80 00', FFFD+'\x00'),
+            ('F1 BF 80 7F', FFFD+'\x7f'), ('F1 BF 80 C0', FFFDx2),
+            ('F1 BF 80 FF', FFFDx2), ('F1 BF BF 00', FFFD+'\x00'),
+            ('F1 BF BF 7F', FFFD+'\x7f'), ('F1 BF BF C0', FFFDx2),
+            ('F1 BF BF FF', FFFDx2), ('F3 00', FFFD+'\x00'),
+            ('F3 7F', FFFD+'\x7f'), ('F3 C0', FFFDx2), ('F3 FF', FFFDx2),
+            ('F3 80 00', FFFD+'\x00'), ('F3 80 7F', FFFD+'\x7f'),
+            ('F3 80 C0', FFFDx2), ('F3 80 FF', FFFDx2),
+            ('F3 BF 00', FFFD+'\x00'), ('F3 BF 7F', FFFD+'\x7f'),
+            ('F3 BF C0', FFFDx2), ('F3 BF FF', FFFDx2),
+            ('F3 80 80 00', FFFD+'\x00'), ('F3 80 80 7F', FFFD+'\x7f'),
+            ('F3 80 80 C0', FFFDx2), ('F3 80 80 FF', FFFDx2),
+            ('F3 80 BF 00', FFFD+'\x00'), ('F3 80 BF 7F', FFFD+'\x7f'),
+            ('F3 80 BF C0', FFFDx2), ('F3 80 BF FF', FFFDx2),
+            ('F3 BF 80 00', FFFD+'\x00'), ('F3 BF 80 7F', FFFD+'\x7f'),
+            ('F3 BF 80 C0', FFFDx2), ('F3 BF 80 FF', FFFDx2),
+            ('F3 BF BF 00', FFFD+'\x00'), ('F3 BF BF 7F', FFFD+'\x7f'),
+            ('F3 BF BF C0', FFFDx2), ('F3 BF BF FF', FFFDx2),
+            ('F4 00', FFFD+'\x00'), ('F4 7F', FFFD+'\x7f'), ('F4 90', FFFDx2),
+            ('F4 BF', FFFDx2), ('F4 C0', FFFDx2), ('F4 FF', FFFDx2),
+            ('F4 80 00', FFFD+'\x00'), ('F4 80 7F', FFFD+'\x7f'),
+            ('F4 80 C0', FFFDx2), ('F4 80 FF', FFFDx2),
+            ('F4 8F 00', FFFD+'\x00'), ('F4 8F 7F', FFFD+'\x7f'),
+            ('F4 8F C0', FFFDx2), ('F4 8F FF', FFFDx2),
+            ('F4 80 80 00', FFFD+'\x00'), ('F4 80 80 7F', FFFD+'\x7f'),
+            ('F4 80 80 C0', FFFDx2), ('F4 80 80 FF', FFFDx2),
+            ('F4 80 BF 00', FFFD+'\x00'), ('F4 80 BF 7F', FFFD+'\x7f'),
+            ('F4 80 BF C0', FFFDx2), ('F4 80 BF FF', FFFDx2),
+            ('F4 8F 80 00', FFFD+'\x00'), ('F4 8F 80 7F', FFFD+'\x7f'),
+            ('F4 8F 80 C0', FFFDx2), ('F4 8F 80 FF', FFFDx2),
+            ('F4 8F BF 00', FFFD+'\x00'), ('F4 8F BF 7F', FFFD+'\x7f'),
+            ('F4 8F BF C0', FFFDx2), ('F4 8F BF FF', FFFDx2)
+        ]
+        for seq, res in sequences:
+            self.assertCorrectUTF8Decoding(self.to_bytestring(seq), res,
+                                           'invalid continuation byte')
+
     def test_codecs_idna(self):
         # Test whether trailing dot is preserved
         self.assertEqual("www.python.org.".encode("idna"), b"www.python.org.")