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gh-155974: Restore the window attributes when a curses write fails #155975

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gh-155974: Restore the window attributes when a curses write fails #155975

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15 changes: 15 additions & 0 deletions Lib/test/test_curses.py
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Original file line number Diff line number Diff line change
Expand Up @@ -895,6 +895,21 @@ def test_output_string_embedded_null_chars(self):
self.assertRaises(ValueError, stdscr.insstr, arg)
self.assertRaises(ValueError, stdscr.insnstr, arg, 1)

def test_output_string_attr_restored(self):
# A write with an attr restores the window rendition afterwards,
# whether it succeeded or failed.
win = curses.newwin(2, 10, 0, 0)
for func, args in [(win.addstr, ('x',)), (win.addnstr, ('x', 1)),
(win.insstr, ('x',)), (win.insnstr, ('x', 1))]:
with self.subTest(func.__qualname__):
win.attrset(curses.A_UNDERLINE)
# y=100 is outside the window, so the write fails.
self.assertRaises(curses.error, func, 100, 0, *args,
curses.A_BOLD)
self.assertEqual(win.getattrs(), curses.A_UNDERLINE)
func(0, 0, *args, curses.A_BOLD)
self.assertEqual(win.getattrs(), curses.A_UNDERLINE)

def test_add_string_behavior(self):
# addstr() advances the cursor past the written text; addnstr()
# writes at most n characters.
Expand Down
4 changes: 4 additions & 0 deletions Misc/NEWS.d/next/Library/2026-08-17-22-51-22.gh-issue-155974.Qz3Vb7.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
Fix a regression in Python 3.15: :meth:`~curses.window.addstr`,
:meth:`~curses.window.addnstr`, :meth:`~curses.window.insstr` and
:meth:`~curses.window.insnstr` again restore the window attributes when the
write fails, instead of leaving the temporary *attr* applied.
52 changes: 24 additions & 28 deletions Modules/_cursesmodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2262,15 +2262,14 @@ _curses_window_addstr_impl(PyCursesWindowObject *self, int group_left_1,
}
Py_DECREF(bytesobj);
}
if (rtn == ERR) {
curses_window_set_error(self, funcname, "addstr");
return NULL;
}
if (use_attr) {
rtn = wattrset(self->win, attr_old);
return curses_window_check_err(self, rtn, "wattrset", "addstr");
int attr_rtn = wattrset(self->win, attr_old);
if (rtn != ERR) {
rtn = attr_rtn;
funcname = "wattrset";
}
}
Py_RETURN_NONE;
return curses_window_check_err(self, rtn, funcname, "addstr");
}

/*[clinic input]
Expand Down Expand Up @@ -2373,15 +2372,14 @@ _curses_window_addnstr_impl(PyCursesWindowObject *self, int group_left_1,
}
Py_DECREF(bytesobj);
}
if (rtn == ERR) {
curses_window_set_error(self, funcname, "addnstr");
return NULL;
}
if (use_attr) {
rtn = wattrset(self->win, attr_old);
return curses_window_check_err(self, rtn, "wattrset", "addnstr");
int attr_rtn = wattrset(self->win, attr_old);
if (rtn != ERR) {
rtn = attr_rtn;
funcname = "wattrset";
}
}
Py_RETURN_NONE;
return curses_window_check_err(self, rtn, funcname, "addnstr");
}

/*[clinic input]
Expand Down Expand Up @@ -4094,15 +4092,14 @@ _curses_window_insstr_impl(PyCursesWindowObject *self, int group_left_1,
}
Py_DECREF(bytesobj);
}
if (rtn == ERR) {
curses_window_set_error(self, funcname, "insstr");
return NULL;
}
if (use_attr) {
rtn = wattrset(self->win, attr_old);
return curses_window_check_err(self, rtn, "wattrset", "insstr");
int attr_rtn = wattrset(self->win, attr_old);
if (rtn != ERR) {
rtn = attr_rtn;
funcname = "wattrset";
}
}
Py_RETURN_NONE;
return curses_window_check_err(self, rtn, funcname, "insstr");
}

/*[clinic input]
Expand Down Expand Up @@ -4206,15 +4203,14 @@ _curses_window_insnstr_impl(PyCursesWindowObject *self, int group_left_1,
}
Py_DECREF(bytesobj);
}
if (rtn == ERR) {
curses_window_set_error(self, funcname, "insnstr");
return NULL;
}
if (use_attr) {
rtn = wattrset(self->win, attr_old);
return curses_window_check_err(self, rtn, "wattrset", "insnstr");
int attr_rtn = wattrset(self->win, attr_old);
if (rtn != ERR) {
rtn = attr_rtn;
funcname = "wattrset";
}
}
Py_RETURN_NONE;
return curses_window_check_err(self, rtn, funcname, "insnstr");
}

/*[clinic input]
Expand Down
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