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gh-156138: Keep the color pair when a curses write restores the rendition #156139

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Merged
serhiy-storchaka merged 1 commit into from
Aug 21, 2026
+98 −16
Merged

gh-156138: Keep the color pair when a curses write restores the rendition #156139

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24 changes: 24 additions & 0 deletions Lib/test/test_curses.py
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Original file line number Diff line number Diff line change
Expand Up @@ -910,6 +910,30 @@ def test_output_string_attr_restored(self):
func(0, 0, *args, curses.A_BOLD)
self.assertEqual(win.getattrs(), curses.A_UNDERLINE)

@requires_colors
@requires_curses_window_meth('color_set')
@requires_curses_window_meth('attr_get')
def test_output_string_pair_restored(self):
# The rendition put back after a write includes the color pair, also
# when it is larger than the A_COLOR field of a chtype holds.
pairs = [7]
if curses.has_extended_color_support() and curses.COLOR_PAIRS > 300:
pairs.append(300)
win = curses.newwin(2, 10, 0, 0)
for pair in pairs:
curses.init_pair(pair, curses.COLOR_RED, curses.COLOR_BLACK)
for func, args in [(win.addstr, ('x',)), (win.addnstr, ('x', 1)),
(win.insstr, ('x',)), (win.insnstr, ('x', 1))]:
with self.subTest(func.__qualname__, pair=pair):
win.color_set(pair)
func(0, 0, *args, curses.A_BOLD)
self.assertEqual(win.attr_get()[1], pair)
win.color_set(pair)
# y=100 is outside the window, so the write fails.
self.assertRaises(curses.error, func, 100, 0, *args,
curses.A_BOLD)
self.assertEqual(win.attr_get()[1], pair)

def test_add_string_behavior(self):
# addstr() advances the cursor past the written text; addnstr()
# writes at most n characters.
Expand Down
90 changes: 74 additions & 16 deletions Modules/_cursesmodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2161,6 +2161,56 @@ curses_wattrset(PyCursesWindowObject *self, attr_t attr, const char *funcname)
return 0;
}

/* Read the rendition a write with an *attr* argument has to put back. The
color pair is read apart from the attributes because the A_COLOR field of a
chtype holds only pairs 0 to 255, while a window can use a larger one. */
static int
curses_wattr_save(PyCursesWindowObject *self, attr_t *attrs, int *pair,
const char *funcname)
{
#if defined(HAVE_CURSES_WATTR_GET) && defined(HAVE_CURSES_WATTR_SET)
int rtn;
#if _NCURSES_EXTENDED_COLOR_FUNCS
short legacy_pair;
rtn = wattr_get(self->win, attrs, &legacy_pair, pair);
#else
short spair;
rtn = wattr_get(self->win, attrs, &spair, NULL);
*pair = spair;
#endif
if (rtn == ERR) {
curses_window_set_error(self, "wattr_get", funcname);
return -1;
}
#else
*attrs = getattrs(self->win);
*pair = 0;
#endif
return 0;
}

/* Put the rendition back. The name of the curses function used is
_CURSES_WATTR_RESTORE_FUNC, for the caller to name it in an error. */
#if defined(HAVE_CURSES_WATTR_GET) && defined(HAVE_CURSES_WATTR_SET)
#define _CURSES_WATTR_RESTORE_FUNC "wattr_set"
#else
#define _CURSES_WATTR_RESTORE_FUNC "wattrset"
#endif

static int
curses_wattr_restore(PyCursesWindowObject *self, attr_t attrs, int pair)
{
#if defined(HAVE_CURSES_WATTR_GET) && defined(HAVE_CURSES_WATTR_SET)
#if _NCURSES_EXTENDED_COLOR_FUNCS
return wattr_set(self->win, attrs, 0, &pair);
#else
return wattr_set(self->win, attrs, (short)pair, NULL);
#endif
#else
return wattrset(self->win, attrs);
#endif
}

/*[clinic input]
_curses.window.addstr

Expand Down Expand Up @@ -2201,6 +2251,7 @@ _curses_window_addstr_impl(PyCursesWindowObject *self, int group_left_1,
wchar_t *wstr = NULL;
#endif
attr_t attr_old = A_NORMAL;
int pair_old = 0;
int use_xy = group_left_1, use_attr = group_right_1;
const char *funcname;

Expand All @@ -2225,8 +2276,9 @@ _curses_window_addstr_impl(PyCursesWindowObject *self, int group_left_1,
return NULL;
}
if (use_attr) {
attr_old = getattrs(self->win);
if (curses_wattrset(self, attr, "addstr") < 0) {
if (curses_wattr_save(self, &attr_old, &pair_old, "addstr") < 0 ||
curses_wattrset(self, attr, "addstr") < 0)
{
curses_release_wstr(strtype, wstr);
Py_XDECREF(bytesobj);
return NULL;
Expand Down Expand Up @@ -2263,10 +2315,10 @@ _curses_window_addstr_impl(PyCursesWindowObject *self, int group_left_1,
Py_DECREF(bytesobj);
}
if (use_attr) {
int attr_rtn = wattrset(self->win, attr_old);
int attr_rtn = curses_wattr_restore(self, attr_old, pair_old);
if (rtn != ERR) {
rtn = attr_rtn;
funcname = "wattrset";
funcname = _CURSES_WATTR_RESTORE_FUNC;
}
}
return curses_window_check_err(self, rtn, funcname, "addstr");
Expand Down Expand Up @@ -2315,6 +2367,7 @@ _curses_window_addnstr_impl(PyCursesWindowObject *self, int group_left_1,
wchar_t *wstr = NULL;
#endif
attr_t attr_old = A_NORMAL;
int pair_old = 0;
int use_xy = group_left_1, use_attr = group_right_1;
const char *funcname;

Expand All @@ -2339,8 +2392,9 @@ _curses_window_addnstr_impl(PyCursesWindowObject *self, int group_left_1,
return NULL;

if (use_attr) {
attr_old = getattrs(self->win);
if (curses_wattrset(self, attr, "addnstr") < 0) {
if (curses_wattr_save(self, &attr_old, &pair_old, "addnstr") < 0 ||
curses_wattrset(self, attr, "addnstr") < 0)
{
curses_release_wstr(strtype, wstr);
Py_XDECREF(bytesobj);
return NULL;
Expand Down Expand Up @@ -2373,10 +2427,10 @@ _curses_window_addnstr_impl(PyCursesWindowObject *self, int group_left_1,
Py_DECREF(bytesobj);
}
if (use_attr) {
int attr_rtn = wattrset(self->win, attr_old);
int attr_rtn = curses_wattr_restore(self, attr_old, pair_old);
if (rtn != ERR) {
rtn = attr_rtn;
funcname = "wattrset";
funcname = _CURSES_WATTR_RESTORE_FUNC;
}
}
return curses_window_check_err(self, rtn, funcname, "addnstr");
Expand Down Expand Up @@ -4035,6 +4089,7 @@ _curses_window_insstr_impl(PyCursesWindowObject *self, int group_left_1,
wchar_t *wstr = NULL;
#endif
attr_t attr_old = A_NORMAL;
int pair_old = 0;
int use_xy = group_left_1, use_attr = group_right_1;
const char *funcname;

Expand All @@ -4059,8 +4114,9 @@ _curses_window_insstr_impl(PyCursesWindowObject *self, int group_left_1,
return NULL;

if (use_attr) {
attr_old = getattrs(self->win);
if (curses_wattrset(self, attr, "insstr") < 0) {
if (curses_wattr_save(self, &attr_old, &pair_old, "insstr") < 0 ||
curses_wattrset(self, attr, "insstr") < 0)
{
curses_release_wstr(strtype, wstr);
Py_XDECREF(bytesobj);
return NULL;
Expand Down Expand Up @@ -4093,10 +4149,10 @@ _curses_window_insstr_impl(PyCursesWindowObject *self, int group_left_1,
Py_DECREF(bytesobj);
}
if (use_attr) {
int attr_rtn = wattrset(self->win, attr_old);
int attr_rtn = curses_wattr_restore(self, attr_old, pair_old);
if (rtn != ERR) {
rtn = attr_rtn;
funcname = "wattrset";
funcname = _CURSES_WATTR_RESTORE_FUNC;
}
}
return curses_window_check_err(self, rtn, funcname, "insstr");
Expand Down Expand Up @@ -4147,6 +4203,7 @@ _curses_window_insnstr_impl(PyCursesWindowObject *self, int group_left_1,
wchar_t *wstr = NULL;
#endif
attr_t attr_old = A_NORMAL;
int pair_old = 0;
int use_xy = group_left_1, use_attr = group_right_1;
const char *funcname;

Expand All @@ -4171,8 +4228,9 @@ _curses_window_insnstr_impl(PyCursesWindowObject *self, int group_left_1,
return NULL;

if (use_attr) {
attr_old = getattrs(self->win);
if (curses_wattrset(self, attr, "insnstr") < 0) {
if (curses_wattr_save(self, &attr_old, &pair_old, "insnstr") < 0 ||
curses_wattrset(self, attr, "insnstr") < 0)
{
curses_release_wstr(strtype, wstr);
return NULL;
}
Expand Down Expand Up @@ -4204,10 +4262,10 @@ _curses_window_insnstr_impl(PyCursesWindowObject *self, int group_left_1,
Py_DECREF(bytesobj);
}
if (use_attr) {
int attr_rtn = wattrset(self->win, attr_old);
int attr_rtn = curses_wattr_restore(self, attr_old, pair_old);
if (rtn != ERR) {
rtn = attr_rtn;
funcname = "wattrset";
funcname = _CURSES_WATTR_RESTORE_FUNC;
}
}
return curses_window_check_err(self, rtn, funcname, "insnstr");
Expand Down
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