fix: a refused write also marks a closed window

A window can still answer tcgetattr while refusing writes. The check now
tries both, as the audit asked, and takes the terminal itself so a stand-in
without a descriptor is never read.

install.py

@@ -12969,7 +12969,7 @@ def run_tui(args: argparse.Namespace) -> int:
                 # The result is printed in the terminal on the way out.
                 state.exit_code = state.code if state.code is not None else 1
     except Exception as exc:  # noqa: BLE001
-        if flags["term"] or _closed_terminal(exc, terminal.fd):
+        if flags["term"] or _closed_terminal(exc, terminal):
             # The window closed under a screen that was changing, or the
             # SIGCONT that comes with its SIGHUP put the screen back: the
             # write failed before the signal was read. That is its exit.
@@ -13033,28 +13033,30 @@ def _tui_startup(args: argparse.Namespace) -> tuple[TuiState, list[tuple]] | Non
 _CLOSED_TERMINAL = frozenset({errno.EIO, errno.EPIPE, errno.ENXIO})
 
 
-def _closed_terminal(exc: BaseException, fd: int | None = None) -> bool:
+def _closed_terminal(exc: BaseException, terminal: _TuiTerminal | None = None) -> bool:
     """Whether exc is the terminal gone: an OSError, or a termios.error,
     whose first argument is the errno, answering EIO, EPIPE or ENXIO, and,
-    given the terminal's fd, that terminal no longer answering. A failing
-    SD card answers EIO too, and that read error is kept in a crash log."""
+    given the terminal, that terminal no longer answering. A failing SD
+    card answers EIO too, and that read error is kept in a crash log."""
     if isinstance(exc, OSError):
         closed = exc.errno in _CLOSED_TERMINAL
     elif type(exc).__name__ == "error" and type(exc).__module__ == "termios":
         closed = bool(exc.args) and exc.args[0] in _CLOSED_TERMINAL
     else:
         closed = False
-    return closed and (fd is None or _terminal_gone(fd))
+    return closed and (terminal is None or _terminal_gone(terminal))
 
 
-def _terminal_gone(fd: int) -> bool:
-    """Whether the terminal at fd hung up: a closed window answers EIO to
-    tcgetattr, a live one its settings."""
+def _terminal_gone(terminal: _TuiTerminal) -> bool:
+    """Whether the terminal hung up: a closed window answers EIO to
+    tcgetattr and to a write, a live one its settings."""
     import termios  # noqa: PLC0415
 
     try:
-        termios.tcgetattr(fd)
-    except (termios.error, OSError):
+        termios.tcgetattr(terminal.fd)
+        terminal.stdout.write("")
+        terminal.stdout.flush()
+    except (termios.error, OSError, ValueError):
         return True
     return False
 

tests/test_install_tui.py

@@ -2576,16 +2576,21 @@ class AReadErrorIsNotAClosedWindow(unittest.TestCase):
         import pty
 
         master, slave = pty.openpty()
+        screen = open(os.dup(slave), "w", encoding="utf-8")  # noqa: SIM115
+        terminal = mock.Mock(fd=slave, stdout=screen)
         try:
             card = OSError(errno.EIO, "Input/output error", "/media/card/bios/x.bin")
-            self.assertFalse(install._closed_terminal(card, slave))
+            self.assertFalse(install._closed_terminal(card, terminal))
             self.assertFalse(install._closed_terminal(
-                OSError(errno.ENOENT, "No such file"), slave))
+                OSError(errno.ENOENT, "No such file"), terminal))
             os.close(master)
             master = -1
-            self.assertTrue(install._closed_terminal(card, slave))
-            self.assertTrue(install._closed_terminal(termios.error(errno.EIO, "gone"), slave))
+            self.assertTrue(install._closed_terminal(card, terminal))
+            self.assertTrue(install._closed_terminal(termios.error(errno.EIO, "gone"),
+                                                     terminal))
         finally:
+            with contextlib.suppress(OSError):
+                screen.close()
             os.close(slave)
             if master >= 0:
                 os.close(master)