bpo-35062: Fix parsing _io.IncrementalNewlineDecoder's *translate* argument. (GH-10217)

_io.IncrementalNewlineDecoder's initializer possibly assigns out-of-range
value to the bitwise struct field.

3 files changed, 13 insertions, 1 deletions

diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index abd5538..d927bb9 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -3748,6 +3748,16 @@ class IncrementalNewlineDecoderTest(unittest.TestCase):
         dec = self.IncrementalNewlineDecoder(None, translate=True)
         _check(dec)
 
+    def test_translate(self):
+        # issue 35062
+        for translate in (-2, -1, 1, 2):
+            decoder = codecs.getincrementaldecoder("utf-8")()
+            decoder = self.IncrementalNewlineDecoder(decoder, translate)
+            self.check_newline_decoding_utf8(decoder)
+        decoder = codecs.getincrementaldecoder("utf-8")()
+        decoder = self.IncrementalNewlineDecoder(decoder, translate=0)
+        self.assertEqual(decoder.decode(b"\r\r\n"), "\r\r\n")
+
 class CIncrementalNewlineDecoderTest(IncrementalNewlineDecoderTest):
     pass
 
diff --git a/Misc/NEWS.d/next/Library/2018-10-29-23-09-24.bpo-35062.dQS1ng.rst b/Misc/NEWS.d/next/Library/2018-10-29-23-09-24.bpo-35062.dQS1ng.rst
new file mode 100644
index 0000000..b77ed86
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-10-29-23-09-24.bpo-35062.dQS1ng.rst
@@ -0,0 +1,2 @@
+Fix incorrect parsing of :class:`_io.IncrementalNewlineDecoder`'s
+*translate* argument.
diff --git a/Modules/_io/textio.c b/Modules/_io/textio.c
index 3a3667b..be42777 100644
--- a/Modules/_io/textio.c
+++ b/Modules/_io/textio.c
@@ -261,7 +261,7 @@ _io_IncrementalNewlineDecoder___init___impl(nldecoder_object *self,
     }
     Py_INCREF(self->errors);
 
-    self->translate = translate;
+    self->translate = translate ? 1 : 0;
     self->seennl = 0;
     self->pendingcr = 0;