gh-43414: os.get_terminal_size() should use file descriptors in Windows

Lib/test/test_os.py

@@ -3657,6 +3657,19 @@ def test_stty_match(self):
             raise
         self.assertEqual(expected, actual)
 
+    @unittest.skipUnless(sys.platform == 'win32', 'Windows specific test')
+    def test_windows_fd(self):
+        """Check if get_terminal_size() returns a meaningful value in Windows"""
+        try:
+            conout = open('conout$', 'w')
+        except OSError:
+            self.skipTest('failed to open conout$')
+        with conout:
+            size = os.get_terminal_size(conout.fileno())
+
+        self.assertGreaterEqual(size.columns, 0)
+        self.assertGreaterEqual(size.lines, 0)
+
 
 @unittest.skipUnless(hasattr(os, 'memfd_create'), 'requires os.memfd_create')
 @support.requires_linux_version(3, 17)

Misc/NEWS.d/next/Windows/2022-05-28-19-36-13.gh-issue-43414.NGMJ3g.rst

@@ -0,0 +1,2 @@
+:func:`os.get_terminal_size` now attempts to read the size from any provided
+handle, rather than only supporting file descriptors 0, 1 and 2.

Modules/posixmodule.c

@@ -13244,24 +13244,11 @@ os_get_terminal_size_impl(PyObject *module, int fd)
 
 #ifdef TERMSIZE_USE_CONIO
     {
-        DWORD nhandle;
         HANDLE handle;
         CONSOLE_SCREEN_BUFFER_INFO csbi;
-        switch (fd) {
-        case 0: nhandle = STD_INPUT_HANDLE;
-            break;
-        case 1: nhandle = STD_OUTPUT_HANDLE;
-            break;
-        case 2: nhandle = STD_ERROR_HANDLE;
-            break;
-        default:
-            return PyErr_Format(PyExc_ValueError, "bad file descriptor");
-        }
-        handle = GetStdHandle(nhandle);
-        if (handle == NULL)
-            return PyErr_Format(PyExc_OSError, "handle cannot be retrieved");
+        handle = _Py_get_osfhandle(fd);
         if (handle == INVALID_HANDLE_VALUE)
-            return PyErr_SetFromWindowsErr(0);
+            return NULL;
 
         if (!GetConsoleScreenBufferInfo(handle, &csbi))
             return PyErr_SetFromWindowsErr(0);