A title's descriptors are taken as never being terminals: a file or
pipe gets ENOTTY with the termios untouched, a socket gets what its
protocol answers a termios ioctl on FreeBSD (EADDRNOTAVAIL for AF_INET,
EOPNOTSUPP otherwise), and a closed or invalid descriptor EBADF.
tcsetattr gives EINVAL for an action other than TCSANOW, TCSADRAIN or
TCSAFLUSH, with or without TCSASOFT, before anything else, and EFAULT
for a null termios before the descriptor is checked; with TCSASOFT a
null termios throws, where FreeBSD's libc faults copying it. What the
console gives a title as descriptors 0 to 2 is unknown, as recorded in
TechnicalDebt.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Jan Šlégl