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[3.7] bpo-19865: ctypes.create_unicode_buffer() supports non-BMP strings on Windows (GH-14081) #14087

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Merged
miss-islington merged 1 commit into from
Jun 14, 2019
Merged

[3.7] bpo-19865: ctypes.create_unicode_buffer() supports non-BMP strings on Windows (GH-14081) #14087

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10 changes: 9 additions & 1 deletion Lib/ctypes/__init__.py
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Original file line number Diff line number Diff line change
Expand Up @@ -279,7 +279,15 @@ def create_unicode_buffer(init, size=None):
"""
if isinstance(init, str):
if size is None:
size = len(init)+1
if sizeof(c_wchar) == 2:
# UTF-16 requires a surrogate pair (2 wchar_t) for non-BMP
# characters (outside [U+0000; U+FFFF] range). +1 for trailing
# NUL character.
size = sum(2 if ord(c) > 0xFFFF else 1 for c in init) + 1
else:
# 32-bit wchar_t (1 wchar_t per Unicode character). +1 for
# trailing NUL character.
size = len(init) + 1
buftype = c_wchar * size
buf = buftype()
buf.value = init
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9 changes: 9 additions & 0 deletions Lib/ctypes/test/test_buffers.py
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Expand Up @@ -60,5 +60,14 @@ def test_unicode_conversion(self):
self.assertEqual(b[::2], "ac")
self.assertEqual(b[::5], "a")

@need_symbol('c_wchar')
def test_create_unicode_buffer_non_bmp(self):
expected = 5 if sizeof(c_wchar) == 2 else 3
for s in '\U00010000\U00100000', '\U00010000\U0010ffff':
b = create_unicode_buffer(s)
self.assertEqual(len(b), expected)
self.assertEqual(b[-1], '\0')


if __name__ == "__main__":
unittest.main()
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2019-06-14-08-30-16.bpo-19865.FRGH4I.rst
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@@ -0,0 +1,2 @@
:func:`ctypes.create_unicode_buffer()` now also supports non-BMP characters
on platforms with 16-bit :c:type:`wchar_t` (for example, Windows and AIX).