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gh-82052: Don't send partial UTF-8 sequences to the Windows API #101103

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Merged
merged 2 commits into from
Jan 17, 2023
Merged

gh-82052: Don't send partial UTF-8 sequences to the Windows API #101103

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aafa8e2
Don't send partial UTF-8 sequences to the Windows API
pfmoore Jan 17, 2023
e59680e
📜🤖 Added by blurb_it.
blurb-it[bot] Jan 17, 2023
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1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Windows/2023-01-17-18-17-58.gh-issue-82052.mWyysT.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Fixed an issue where writing more than 32K of Unicode output to the console screen in one go can result in mojibake.
17 changes: 16 additions & 1 deletion Modules/_io/winconsoleio.c
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Expand Up @@ -954,7 +954,7 @@ _io__WindowsConsoleIO_write_impl(winconsoleio *self, Py_buffer *b)
{
BOOL res = TRUE;
wchar_t *wbuf;
DWORD len, wlen, n = 0;
DWORD len, wlen, orig_len, n = 0;
HANDLE handle;

if (self->fd == -1)
Expand Down Expand Up @@ -984,6 +984,21 @@ _io__WindowsConsoleIO_write_impl(winconsoleio *self, Py_buffer *b)
have to reduce and recalculate. */
while (wlen > 32766 / sizeof(wchar_t)) {
len /= 2;
orig_len = len;
/* Reduce the length until we hit the final byte of a UTF-8 sequence
* (top bit is unset). Fix for github issue 82052.
*/
while (len > 0 && (((char *)b->buf)[len-1] & 0x80) != 0)
--len;
/* If we hit a length of 0, something has gone wrong. This shouldn't
* be possible, as valid UTF-8 can have at most 3 non-final bytes
* before a final one, and our buffer is way longer than that.
* But to be on the safe side, if we hit this issue we just restore
* the original length and let the console API sort it out.
*/
if (len == 0) {
len = orig_len;
}
wlen = MultiByteToWideChar(CP_UTF8, 0, b->buf, len, NULL, 0);
}
Py_END_ALLOW_THREADS
Expand Down