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gh-159739: Preserve CJK codec state across chunk boundaries and callbacks #160400

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25 changes: 24 additions & 1 deletion Lib/test/test_multibytecodec.py
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,10 @@ def test_nullcoding(self):
self.assertEqual(str(b'', enc), '')
self.assertEqual(''.encode(enc), b'')

def test_hz_tilde_at_buffer_boundary(self):
text = 'a' + '中a' * 6 + '~'
self.assertEqual(text.encode('hz').decode('hz'), text)

def test_str_decode(self):
for enc in ALL_CJKENCODINGS:
self.assertEqual('abcd'.encode(enc), b'abcd')
Expand Down Expand Up @@ -91,6 +95,12 @@ def test_decode_unicode(self):

class Test_IncrementalEncoder(unittest.TestCase):

def test_iso2022_kr_reset(self):
encoder = codecs.getincrementalencoder('iso2022_kr')()
encoder.encode('가')
encoder.reset()
self.assertEqual(encoder.encode('가', final=True), '가'.encode('iso2022_kr'))

def test_stateless(self):
# cp949 encoder isn't stateful at all.
encoder = codecs.getincrementalencoder('cp949')()
Expand Down Expand Up @@ -242,6 +252,19 @@ def test_subinterp(self):

class Test_IncrementalDecoder(unittest.TestCase):

def test_iso2022_split_escape(self):
raw = b'\x1b$0000000B'
decoder = codecs.getincrementaldecoder('iso2022_jp')('replace')
decoded = decoder.decode(raw[:-1]) + decoder.decode(raw[-1:], final=True)
self.assertEqual(decoded, raw.decode('iso2022_jp', 'replace'))

def test_iso2022_reset(self):
decoder = codecs.getincrementaldecoder('iso2022_jp')()
decoder.decode(b'\x1b%')
decoder.reset()
with self.assertRaises(UnicodeDecodeError):
decoder.decode(b'\xff', final=True)

def test_dbcs(self):
# cp949 decoder is simple with only 1 or 2 bytes sequences.
decoder = codecs.getincrementaldecoder('cp949')()
Expand Down Expand Up @@ -325,7 +348,7 @@ def test_setstate_validates_input(self):
self.assertRaises(TypeError, decoder.setstate, 123)
self.assertRaises(TypeError, decoder.setstate, ("invalid", 0))
self.assertRaises(TypeError, decoder.setstate, (b"1234", "invalid"))
self.assertRaises(UnicodeDecodeError, decoder.setstate, (b"123456789", 0))
self.assertRaises(UnicodeDecodeError, decoder.setstate, (b"0" * 17, 0))

def test_setstate_invalid_designation(self):
# gh-153603: an unknown charset designation in the state must not crash
Expand Down
4 changes: 4 additions & 0 deletions Misc/NEWS.d/next/Library/2026-10-22-16-23-01.gh-issue-159739.CjkR5a.rst
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@@ -0,0 +1,4 @@
Fix HZ encoding of a tilde at an output buffer boundary and ISO-2022 decoding
of split escape sequences. Reset ISO-2022 incremental codecs to their initial
state. Keep multibyte codec tables and custom encoder error policies alive
when Python code replaces them during use.
10 changes: 6 additions & 4 deletions Modules/cjkcodecs/_codecs_cn.c
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Original file line number Diff line number Diff line change
Expand Up @@ -361,11 +361,13 @@ ENCODER(hz)
NEXT_OUT(2);
state->c[CN_STATE_OFFSET] = 0;
}
WRITEBYTE1((unsigned char)c);
NEXT(1, 1);
if (c == '~') {
WRITEBYTE1('~');
NEXT_OUT(1);
WRITEBYTE2('~', '~');
NEXT(1, 2);
}
else {
WRITEBYTE1((unsigned char)c);
NEXT(1, 1);
}
continue;
}
Expand Down
7 changes: 2 additions & 5 deletions Modules/cjkcodecs/_codecs_iso2022.c
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Original file line number Diff line number Diff line change
Expand Up @@ -174,9 +174,8 @@ ENCODER_RESET(iso2022)
if (STATE_G0 != CHARSET_ASCII) {
WRITEBYTE3(ESC, '(', 'B');
NEXT_OUT(3);
STATE_SETG0(CHARSET_ASCII);
}
return 0;
return iso2022_encode_init(state, codec);
}

ENCODER(iso2022)
Expand Down Expand Up @@ -311,9 +310,7 @@ DECODER_INIT(iso2022)

DECODER_RESET(iso2022)
{
STATE_SETG0(CHARSET_ASCII);
STATE_CLEARFLAG(F_SHIFTED);
return 0;
return iso2022_decode_init(state, codec);
}

static Py_ssize_t
Expand Down
23 changes: 19 additions & 4 deletions Modules/cjkcodecs/multibytecodec.c
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Original file line number Diff line number Diff line change
Expand Up @@ -514,6 +514,11 @@ multibytecodec_encode(const MultibyteCodec *codec,
if (datalen == 0 && !(flags & MBENC_RESET))
return Py_GetConstant(Py_CONSTANT_EMPTY_BYTES);

/* A callback may change a stateful encoder's errors attribute. */
if (ERROR_ISCUSTOM(errors)) {
Py_INCREF(errors);
}

buf.excobj = NULL;
buf.writer = NULL;
buf.inobj = text; /* borrowed reference */
Expand Down Expand Up @@ -567,10 +572,12 @@ multibytecodec_encode(const MultibyteCodec *codec,
if (inpos_t)
*inpos_t = buf.inpos;
Py_XDECREF(buf.excobj);
ERROR_DECREF(errors);
return PyBytesWriter_FinishWithPointer(buf.writer, buf.outbuf);

errorexit:
Py_XDECREF(buf.excobj);
ERROR_DECREF(errors);
PyBytesWriter_Discard(buf.writer);
return NULL;
}
Expand Down Expand Up @@ -1101,7 +1108,7 @@ mbiencoder_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
self->codec->encinit(&self->state, self->codec) != 0)
goto errorexit;

Py_DECREF(codec);
self->codec_owner = codec;
return (PyObject *)self;

errorexit:
Expand All @@ -1122,6 +1129,7 @@ mbiencoder_traverse(PyObject *op, visitproc visit, void *arg)
MultibyteIncrementalEncoderObject *self = _MultibyteIncrementalEncoderObject_CAST(op);
if (ERROR_ISCUSTOM(self->errors))
Py_VISIT(self->errors);
Py_VISIT(self->codec_owner);
return 0;
}

Expand All @@ -1133,6 +1141,7 @@ mbiencoder_dealloc(PyObject *op)
PyObject_GC_UnTrack(self);
ERROR_DECREF(self->errors);
Py_CLEAR(self->pending);
Py_XDECREF(self->codec_owner);
tp->tp_free(self);
Py_DECREF(tp);
}
Expand Down Expand Up @@ -1384,7 +1393,7 @@ mbidecoder_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
self->codec->decinit(&self->state, self->codec) != 0)
goto errorexit;

Py_DECREF(codec);
self->codec_owner = codec;
return (PyObject *)self;

errorexit:
Expand All @@ -1405,6 +1414,7 @@ mbidecoder_traverse(PyObject *op, visitproc visit, void *arg)
MultibyteIncrementalDecoderObject *self = _MultibyteIncrementalDecoderObject_CAST(op);
if (ERROR_ISCUSTOM(self->errors))
Py_VISIT(self->errors);
Py_VISIT(self->codec_owner);
return 0;
}

Expand All @@ -1415,6 +1425,7 @@ mbidecoder_dealloc(PyObject *op)
PyTypeObject *tp = Py_TYPE(self);
PyObject_GC_UnTrack(self);
ERROR_DECREF(self->errors);
Py_XDECREF(self->codec_owner);
tp->tp_free(self);
Py_DECREF(tp);
}
Expand Down Expand Up @@ -1703,7 +1714,7 @@ mbstreamreader_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
self->codec->decinit(&self->state, self->codec) != 0)
goto errorexit;

Py_DECREF(codec);
self->codec_owner = codec;
return (PyObject *)self;

errorexit:
Expand All @@ -1725,6 +1736,7 @@ mbstreamreader_traverse(PyObject *op, visitproc visit, void *arg)
if (ERROR_ISCUSTOM(self->errors))
Py_VISIT(self->errors);
Py_VISIT(self->stream);
Py_VISIT(self->codec_owner);
return 0;
}

Expand All @@ -1736,6 +1748,7 @@ mbstreamreader_dealloc(PyObject *op)
PyObject_GC_UnTrack(self);
ERROR_DECREF(self->errors);
Py_XDECREF(self->stream);
Py_XDECREF(self->codec_owner);
tp->tp_free(self);
Py_DECREF(tp);
}
Expand Down Expand Up @@ -1927,7 +1940,7 @@ mbstreamwriter_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
self->codec->encinit(&self->state, self->codec) != 0)
goto errorexit;

Py_DECREF(codec);
self->codec_owner = codec;
return (PyObject *)self;

errorexit:
Expand All @@ -1949,6 +1962,7 @@ mbstreamwriter_traverse(PyObject *op, visitproc visit, void *arg)
if (ERROR_ISCUSTOM(self->errors))
Py_VISIT(self->errors);
Py_VISIT(self->stream);
Py_VISIT(self->codec_owner);
return 0;
}

Expand All @@ -1960,6 +1974,7 @@ mbstreamwriter_dealloc(PyObject *op)
PyObject_GC_UnTrack(self);
ERROR_DECREF(self->errors);
Py_XDECREF(self->stream);
Py_XDECREF(self->codec_owner);
tp->tp_free(self);
Py_DECREF(tp);
}
Expand Down
4 changes: 3 additions & 1 deletion Modules/cjkcodecs/multibytecodec.h
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Expand Up @@ -77,6 +77,7 @@ typedef struct {
#define _MultibyteStatefulCodec_HEAD \
PyObject_HEAD \
const MultibyteCodec *codec; \
PyObject *codec_owner; \
MultibyteCodec_State state; \
PyObject *errors;
typedef struct {
Expand All @@ -91,7 +92,8 @@ typedef struct {
_MultibyteStatefulEncoder_HEAD
} MultibyteStatefulEncoderContext;

#define MAXDECPENDING 8
/* ISO-2022 may retain an incomplete escape sequence up to 15 bytes. */
#define MAXDECPENDING 16
#define _MultibyteStatefulDecoder_HEAD \
_MultibyteStatefulCodec_HEAD \
unsigned char pending[MAXDECPENDING]; \
Expand Down
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