gh-157581: can_colorize should handle unexpected exceptions

Lib/_colorize.py

@@ -603,6 +603,8 @@ def _safe_getenv(k: str, fallback: str | None = None) -> str | None:
         return os.isatty(file.fileno())
     except OSError:
         return hasattr(file, "isatty") and file.isatty()
+    except ValueError:
+        return False
 
 
 default_theme = Theme()

Lib/test/test__colorize.py

@@ -187,6 +187,11 @@ def test_colorized_detection_checks_for_file(self):
                 file.isatty.return_value = False
                 self.assertEqual(_colorize.can_colorize(file=file), False)
 
+            # gh-157581: A closed file raises ValueError from fileno().
+            file = unittest.mock.Mock()
+            file.fileno.side_effect = ValueError
+            self.assertFalse(_colorize.can_colorize(file=file))
+
 
 if __name__ == "__main__":
     unittest.main()

Misc/NEWS.d/next/Library/2026-09-15-21-12-02.gh-issue-157581.qJEepi.rst

@@ -0,0 +1 @@
+Updated :func:``!_colorize.can_colorize`` to not raise when given a closed file stream.