/// The path to the default TTY on linuxpub const TTY_PATH: &str = "/dev/tty"; #[cfg(unix)]pub(crate) mod imp {    use std::{        io::{BufRead, Write},        os::unix::io::{AsRawFd, RawFd},    };     use nix::sys::{termios, termios::Termios};    use parking_lot::{const_mutex, lock_api::MutexGuard, Mutex, RawMutex};     use crate::{unix::TTY_PATH, Error, Mode, Options};     static TERM_STATE: Mutex<Option<Termios>> = const_mutex(None);     /// Ask the user given a `prompt`, returning the result.    pub(crate) fn ask(prompt: &str, Options { mode, .. }: &Options<'_>) -> Result<String, Error> {        match mode {            Mode::Disable => Err(Error::Disabled),            Mode::Hidden => {                let state = TERM_STATE.lock();                let mut in_out = std::fs::OpenOptions::new().write(true).read(true).open(TTY_PATH)?;                let restore = save_term_state_and_disable_echo(state, in_out.as_raw_fd())?;                in_out.write_all(prompt.as_bytes())?;                 let mut buf_read = std::io::BufReader::with_capacity(64, in_out);                let mut out = String::with_capacity(64);                buf_read.read_line(&mut out)?;                 out.pop();                if out.ends_with('\r') {                    out.pop();                }                restore.now()?;                Ok(out)            }            Mode::Visible => {                let mut in_out = std::fs::OpenOptions::new().write(true).read(true).open(TTY_PATH)?;                in_out.write_all(prompt.as_bytes())?;                 let mut buf_read = std::io::BufReader::with_capacity(64, in_out);                let mut out = String::with_capacity(64);                buf_read.read_line(&mut out)?;                Ok(out.trim_end().to_owned())            }        }    }     type TermiosGuard<'a> = MutexGuard<'a, RawMutex, Option<Termios>>;     struct RestoreTerminalStateOnDrop<'a> {        state: TermiosGuard<'a>,        fd: RawFd,    }     impl<'a> RestoreTerminalStateOnDrop<'a> {        fn now(mut self) -> Result<(), Error> {            let state = self.state.take().expect("BUG: we exist only if something is saved");            termios::tcsetattr(self.fd, termios::SetArg::TCSAFLUSH, &state)?;            Ok(())        }    }     impl<'a> Drop for RestoreTerminalStateOnDrop<'a> {        fn drop(&mut self) {            if let Some(state) = self.state.take() {                termios::tcsetattr(self.fd, termios::SetArg::TCSAFLUSH, &state).ok();            }        }    }     fn save_term_state_and_disable_echo(        mut state: TermiosGuard<'_>,        fd: RawFd,    ) -> Result<RestoreTerminalStateOnDrop<'_>, Error> {        assert!(            state.is_none(),            "BUG: recursive calls are not possible and we restore afterwards"        );         let prev = termios::tcgetattr(fd)?;        let mut new = prev.clone();        *state = prev.into();         new.local_flags &= !termios::LocalFlags::ECHO;        new.local_flags |= termios::LocalFlags::ECHONL;        termios::tcsetattr(fd, termios::SetArg::TCSAFLUSH, &new)?;         Ok(RestoreTerminalStateOnDrop { fd, state })    }}