[3.13] gh-134210: handle signals in `_curses.window.getch` (GH-134326) (#134784)

(cherry picked from commit 51762b6cad)

Misc/NEWS.d/next/Library/2025-05-24-13-10-35.gh-issue-134210.0IuMY2.rst

@@ -0,0 +1,2 @@
+:func:`curses.window.getch` now correctly handles signals. Patch by Bénédikt
+Tran.

Modules/_cursesmodule.c

@@ -1385,7 +1385,7 @@ _curses_window_getbkgd_impl(PyCursesWindowObject *self)
 }
 
 /*[clinic input]
-_curses.window.getch -> int
+_curses.window.getch
 
     [
     y: int
@@ -1402,10 +1402,10 @@ keypad keys and so on return numbers higher than 256.  In no-delay mode, -1
 is returned if there is no input, else getch() waits until a key is pressed.
 [clinic start generated code]*/
 
-static int
+static PyObject *
 _curses_window_getch_impl(PyCursesWindowObject *self, int group_right_1,
                           int y, int x)
-/*[clinic end generated code: output=980aa6af0c0ca387 input=bb24ebfb379f991f]*/
+/*[clinic end generated code: output=e1639e87d545e676 input=73f350336b1ee8c8]*/
 {
     int rtn;
 
@@ -1418,7 +1418,17 @@ _curses_window_getch_impl(PyCursesWindowObject *self, int group_right_1,
     }
     Py_END_ALLOW_THREADS
 
-    return rtn;
+    if (rtn == ERR) {
+        // We suppress ERR returned by wgetch() in nodelay mode
+        // after we handled possible interruption signals.
+        if (PyErr_CheckSignals()) {
+            return NULL;
+        }
+        // ERR is an implementation detail, so to be on the safe side,
+        // we forcibly set the return value to -1 as documented above.
+        rtn = -1;
+    }
+    return PyLong_FromLong(rtn);
 }
 
 /*[clinic input]

Modules/clinic/_cursesmodule.c.h

@@ -768,7 +768,7 @@ PyDoc_STRVAR(_curses_window_getch__doc__,
 #define _CURSES_WINDOW_GETCH_METHODDEF    \
     {"getch", (PyCFunction)_curses_window_getch, METH_VARARGS, _curses_window_getch__doc__},
 
-static int
+static PyObject *
 _curses_window_getch_impl(PyCursesWindowObject *self, int group_right_1,
                           int y, int x);
 
@@ -779,7 +779,6 @@ _curses_window_getch(PyCursesWindowObject *self, PyObject *args)
     int group_right_1 = 0;
     int y = 0;
     int x = 0;
-    int _return_value;
 
     switch (PyTuple_GET_SIZE(args)) {
         case 0:
@@ -794,11 +793,7 @@ _curses_window_getch(PyCursesWindowObject *self, PyObject *args)
             PyErr_SetString(PyExc_TypeError, "_curses.window.getch requires 0 to 2 arguments");
             goto exit;
     }
-    _return_value = _curses_window_getch_impl(self, group_right_1, y, x);
+    return_value = _curses_window_getch_impl(self, group_right_1, y, x);
-    if ((_return_value == -1) && PyErr_Occurred()) {
-        goto exit;
-    }
-    return_value = PyLong_FromLong((long)_return_value);
 
 exit:
     return return_value;
@@ -4378,4 +4373,4 @@ _curses_has_extended_color_support(PyObject *module, PyObject *Py_UNUSED(ignored
 #ifndef _CURSES_USE_DEFAULT_COLORS_METHODDEF
     #define _CURSES_USE_DEFAULT_COLORS_METHODDEF
 #endif /* !defined(_CURSES_USE_DEFAULT_COLORS_METHODDEF) */
-/*[clinic end generated code: output=8745c1562b537fb4 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=39a35d730a47ea72 input=a9049054013a1b77]*/