pythongh-119770: Make termios ioctl() constants positive

Lib/test/test_termios.py

@@ -211,6 +211,15 @@ def test_constants(self):
         self.assertLess(termios.VTIME, termios.NCCS)
         self.assertLess(termios.VMIN, termios.NCCS)
 
+    def test_ioctl_constants(self):
+        # gh-119770: ioctl() constants must be positive
+        for name in dir(termios):
+            if not name.startswith('TIO'):
+                continue
+            value = getattr(termios, name)
+            with self.subTest(name=name):
+                self.assertGreaterEqual(value, 0)
+
     def test_exception(self):
         self.assertTrue(issubclass(termios.error, Exception))
         self.assertFalse(issubclass(termios.error, OSError))

Misc/NEWS.d/next/Library/2024-05-31-12-57-31.gh-issue-119770.NCtels.rst

@@ -0,0 +1 @@
+Make :mod:`termios` ``ioctl()`` constants positive. Patch by Victor Stinner.

Modules/termios.c

@@ -1352,9 +1352,21 @@ termios_exec(PyObject *mod)
     }
 
     while (constant->name != NULL) {
-        if (PyModule_AddIntConstant(
-            mod, constant->name, constant->value) < 0) {
-            return -1;
+        if (strncmp(constant->name, "TIO", 3) == 0) {
+            // gh-119770: Convert value to unsigned int for ioctl() constants,
+            // constants can be negative on macOS whereas ioctl() expects an
+            // unsigned long 'request'.
+            unsigned int value = constant->value & UINT_MAX;
+            if (PyModule_Add(mod, constant->name,
+                             PyLong_FromUnsignedLong(value)) < 0) {
+                return -1;
+            }
+        }
+        else {
+            if (PyModule_AddIntConstant(
+                mod, constant->name, constant->value) < 0) {
+                return -1;
+            }
         }
         ++constant;
     }