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bpo-21872: fix lzma library decompresses data incompletely #14048

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Merged
gpshead merged 6 commits into from Sep 12, 2019
Merged

bpo-21872: fix lzma library decompresses data incompletely #14048

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1dbbfcf
1. add test case with wrong behavior
wjssz Jun 12, 2019
ad5cdd1
2. fix bug when max_length == -1
wjssz Jun 12, 2019
454b278
3. allow b"" as valid input data for decompress_buf()
wjssz Jun 12, 2019
594d525
4. when max_length >= 0, let needs_input mechanism works
wjssz Jun 12, 2019
05951a6
add more asserts to test case
wjssz Jun 14, 2019
62ba236
update NEWS entry
wjssz Jun 18, 2019
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3. allow b"" as valid input data for decompress_buf()
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@wjssz
wjssz committed Jun 13, 2019
commit 454b278d6a671efe4cf340e81875f9f1a6b40816
4 changes: 2 additions & 2 deletions Lib/test/test_lzma.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1220,8 +1220,8 @@ def test_issue21872(self):
# simulate needs_input mechanism
# output internal state's 11 bytes
out2 = d2.decompress(b'')
self.assertEqual(len(out2), 0) # wrong behavior before fix
self.assertFalse(d2.eof) # wrong behavior before fix
self.assertEqual(len(out2), 11)
self.assertTrue(d2.eof)

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class OpenTestCase(unittest.TestCase):
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6 changes: 3 additions & 3 deletions Modules/_lzmamodule.c
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Expand Up @@ -872,9 +872,6 @@ decompress_buf(Decompressor *d, Py_ssize_t max_length)
PyObject *result;
lzma_stream *lzs = &d->lzs;

if (lzs->avail_in == 0)
return PyBytes_FromStringAndSize(NULL, 0);

if (max_length < 0 || max_length >= INITIAL_BUFFER_SIZE)
result = PyBytes_FromStringAndSize(NULL, INITIAL_BUFFER_SIZE);
else
Expand All @@ -891,7 +888,10 @@ decompress_buf(Decompressor *d, Py_ssize_t max_length)
Py_BEGIN_ALLOW_THREADS
lzret = lzma_code(lzs, LZMA_RUN);
data_size = (char *)lzs->next_out - PyBytes_AS_STRING(result);
if (lzret == LZMA_BUF_ERROR && lzs->avail_in == 0 && lzs->avail_out > 0)
lzret = LZMA_OK; /* That wasn't a real error */
Py_END_ALLOW_THREADS

if (catch_lzma_error(lzret))
goto error;
if (lzret == LZMA_GET_CHECK || lzret == LZMA_NO_CHECK)
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