#[cfg(all(target_os = "linux", not(target_env = "musl"), feature = "libudev"))]
use std::ffi::OsStr;
#[cfg(target_os = "macos")]
use std::ffi::{CStr, CString};
use std::os::unix::prelude::*;
use std::path::Path;
use std::time::Duration;
use std::{io, mem};

#[cfg(target_os = "macos")]
use cf::*;
#[cfg(all(target_os = "linux", not(target_env = "musl"), feature = "libudev"))]
use libudev;
use nix::fcntl::fcntl;
#[cfg(target_os = "macos")]
use nix::libc::{c_char, c_void};
use nix::{self, libc, unistd};
use posix::ioctl::{self, SerialLines};
#[cfg(target_os = "macos")]
use IOKit_sys::*;

use {DataBits, FlowControl, Parity, SerialPort, SerialPortInfo, SerialPortSettings, StopBits};
use {Error, ErrorKind};
#[cfg(any(all(target_os = "linux", not(target_env = "musl"), feature = "libudev"), target_os = "macos"))]
use {SerialPortType, UsbPortInfo};

/// Convenience method for removing exclusive access from
/// a fd and closing it.
fn close(fd: RawFd) {
    // remove exclusive access
    let _ = ioctl::tiocnxcl(fd);

    // On Linux and BSD, we don't need to worry about return
    // type as EBADF means the fd was never open or is already closed
    //
    // Linux and BSD guarantee that for any other error code the
    // fd is already closed, though MacOSX does not.
    //
    // close() also should never be retried, and the error code
    // in most cases in purely informative
    let _ = unistd::close(fd);
}

/// A TTY-based serial port implementation.
///
/// The port will be closed when the value is dropped. However, this struct
/// should not be instantiated directly by using `TTYPort::open()`, instead use
/// the cross-platform `serialport::open()` or
/// `serialport::open_with_settings()`.
#[derive(Debug)]
pub struct TTYPort {
    fd: RawFd,
    timeout: Duration,
    exclusive: bool,
    port_name: Option<String>,
}

impl TTYPort {
    /// Opens a TTY device as a serial port.
    ///
    /// `path` should be the path to a TTY device, e.g., `/dev/ttyS0`.
    ///
    /// Ports are opened in exclusive mode by default. If this is undesireable
    /// behavior, use `TTYPort::set_exclusive(false)`.
    ///
    /// ## Errors
    ///
    /// * `NoDevice` if the device could not be opened. This could indicate that
    ///    the device is already in use.
    /// * `InvalidInput` if `path` is not a valid device name.
    /// * `Io` for any other error while opening or initializing the device.
    pub fn open(path: &Path, settings: &SerialPortSettings) -> ::Result<TTYPort> {
        use nix::fcntl::FcntlArg::F_SETFL;
        use nix::fcntl::OFlag;
        use nix::libc::{self, cfmakeraw, tcflush, tcgetattr, tcsetattr};

        let fd = nix::fcntl::open(
            path,
            OFlag::O_RDWR | OFlag::O_NOCTTY | OFlag::O_NONBLOCK,
            nix::sys::stat::Mode::empty(),
        )?;

        let mut termios = unsafe { mem::uninitialized() };
        let res = unsafe { tcgetattr(fd, &mut termios) };
        if let Err(e) = nix::errno::Errno::result(res) {
            close(fd);
            return Err(e.into());
        }

        // If any of these steps fail, then we should abort creation of the
        // TTYPort and ensure the file descriptor is closed.
        // So we wrap these calls in a block and check the result.
        {
            // setup TTY for binary serial port access
            // Enable reading from the port and ignore all modem control lines
            termios.c_cflag |= libc::CREAD | libc::CLOCAL;
            // Enable raw mode which disables any implicit processing of the input or output data streams
            // This also sets no timeout period and a read will block until at least one character is
            // available.
            unsafe { cfmakeraw(&mut termios) };

            // write settings to TTY
            unsafe { tcsetattr(fd, libc::TCSANOW, &termios) };

            // Read back settings from port and confirm they were applied correctly
            let mut actual_termios = unsafe { mem::uninitialized() };
            unsafe { tcgetattr(fd, &mut actual_termios) };

            if actual_termios.c_iflag != termios.c_iflag
                || actual_termios.c_oflag != termios.c_oflag
                || actual_termios.c_lflag != termios.c_lflag
                || actual_termios.c_cflag != termios.c_cflag
            {
                return Err(Error::new(
                    ErrorKind::Unknown,
                    "Settings did not apply correctly",
                ));
            };

            unsafe { tcflush(fd, libc::TCIOFLUSH) };

            // get exclusive access to device
            ioctl::tiocexcl(fd)?;

            // clear O_NONBLOCK flag
            fcntl(fd, F_SETFL(nix::fcntl::OFlag::empty()))?;

            Ok(())
        }.map_err(|e: Error| {
            close(fd);
            e
        })?;

        let mut port = TTYPort {
            fd,
            timeout: Duration::new(0, 0), // This is overwritten by the subsequent call to `set_all()`
            exclusive: true, // This is guaranteed by the above `ioctl::tiocexcl()` call
            port_name: path.to_str().map(|s| s.to_string()),
        };

        // Then we try and finish setting up the port.
        // If this fails, we also need to be sure to close the
        // file descriptor.
        if let Err(err) = port.set_all(settings) {
            close(fd);
            return Err(err);
        }

        Ok(port)
    }

    /// Returns the exclusivity of the port
    ///
    /// If a port is exclusive, then trying to open the same device path again
    /// will fail.
    pub fn exclusive(&self) -> bool {
        self.exclusive
    }

    /// Sets the exclusivity of the port
    ///
    /// If a port is exclusive, then trying to open the same device path again
    /// will fail.
    ///
    /// See the man pages for the tiocexcl and tiocnxcl ioctl's for more details.
    ///
    /// ## Errors
    ///
    /// * `Io` for any error while setting exclusivity for the port.
    pub fn set_exclusive(&mut self, exclusive: bool) -> ::Result<()> {
        let setting_result = if exclusive {
            ioctl::tiocexcl(self.fd)
        } else {
            ioctl::tiocnxcl(self.fd)
        };

        if let Err(err) = setting_result {
            Err(err)
        } else {
            self.exclusive = exclusive;
            Ok(())
        }
    }

    fn set_pin(&mut self, pin: ioctl::SerialLines, level: bool) -> ::Result<()> {
        let retval = if level {
            ioctl::tiocmbis(self.fd, pin)
        } else {
            ioctl::tiocmbic(self.fd, pin)
        };

        match retval {
            Ok(()) => Ok(()),
            Err(err) => Err(err),
        }
    }

    fn read_pin(&mut self, pin: ioctl::SerialLines) -> ::Result<bool> {
        match ioctl::tiocmget(self.fd) {
            Ok(pins) => Ok(pins.contains(pin)),
            Err(err) => Err(err),
        }
    }

    /// Create a pair of pseudo serial terminals
    ///
    /// ## Returns
    /// Two connected `TTYPort` objects: `(master, slave)`
    ///
    /// ## Errors
    /// Attempting any IO or parameter settings on the slave tty after the master
    /// tty is closed will return errors.
    ///
    /// On some platforms manipulating the master port will fail and only
    /// modifying the slave port is possible.
    ///
    /// ## Examples
    ///
    /// ```
    /// use serialport::posix::TTYPort;
    ///
    /// let (master, slave) = TTYPort::pair().unwrap();
    /// ```
    pub fn pair() -> ::Result<(Self, Self)> {
        // Open the next free pty.
        let next_pty_fd = nix::pty::posix_openpt(nix::fcntl::OFlag::O_RDWR)?;

        // Grant access to the associated slave pty
        nix::pty::grantpt(&next_pty_fd)?;

        // Unlock the slave pty
        nix::pty::unlockpt(&next_pty_fd)?;

        // Get the path of the attached slave ptty
        #[cfg(
            not(
                any(
                    target_os = "linux",
                    target_os = "android",
                    target_os = "emscripten",
                    target_os = "fuchsia"
                )
            )
        )]
        let ptty_name = unsafe { nix::pty::ptsname(&next_pty_fd)? };

        #[cfg(
            any(
                target_os = "linux",
                target_os = "android",
                target_os = "emscripten",
                target_os = "fuchsia"
            )
        )]
        let ptty_name = nix::pty::ptsname_r(&next_pty_fd)?;

        // Open the slave port using default settings
        let slave_tty = TTYPort::open(Path::new(&ptty_name), &Default::default())?;

        // Manually construct the master port here because the
        // `tcgetattr()` doesn't work on Mac, Solaris, and maybe other
        // BSDs when used on the master port.
        let master_tty = TTYPort {
            fd: next_pty_fd.into_raw_fd(),
            timeout: Duration::from_millis(100),
            exclusive: true,
            port_name: None,
        };

        Ok((master_tty, slave_tty))
    }

    #[cfg(
        any(
            target_os = "dragonflybsd",
            target_os = "freebsd",
            target_os = "ios",
            target_os = "macos",
            target_os = "netbsd",
            target_os = "openbsd",
            all(
                target_os = "linux",
                any(target_env = "musl", target_arch = "powerpc", target_arch = "powerpc64")
            )
        )
    )]
    fn get_termios(&self) -> ::Result<libc::termios> {
        let mut termios = unsafe { mem::uninitialized() };
        let res = unsafe { libc::tcgetattr(self.fd, &mut termios) };
        nix::errno::Errno::result(res)?;
        Ok(termios)
    }

    #[cfg(
        any(
            target_os = "android",
            all(
                target_os = "linux",
                not(any(target_env = "musl", target_arch = "powerpc", target_arch = "powerpc64"))
            )
        )
    )]
    fn get_termios(&self) -> ::Result<libc::termios2> {
        ioctl::tcgets2(self.fd)
    }

    #[cfg(
        any(
            target_os = "dragonflybsd",
            target_os = "freebsd",
            target_os = "ios",
            target_os = "macos",
            target_os = "netbsd",
            target_os = "openbsd",
            all(
                target_os = "linux",
                any(target_env = "musl", target_arch = "powerpc", target_arch = "powerpc64")
            )
        )
    )]
    fn set_termios(&self, termios: &libc::termios) -> ::Result<()> {
        let res = unsafe { libc::tcsetattr(self.fd, libc::TCSANOW, termios) };
        nix::errno::Errno::result(res)?;
        Ok(())
    }

    #[cfg(
        any(
            target_os = "android",
            all(
                target_os = "linux",
                not(any(target_env = "musl", target_arch = "powerpc", target_arch = "powerpc64"))
            )
        )
    )]
    fn set_termios(&self, termios2: &libc::termios2) -> ::Result<()> {
        ioctl::tcsets2(self.fd, &termios2)
    }
}

impl Drop for TTYPort {
    fn drop(&mut self) {
        close(self.fd);
    }
}

impl AsRawFd for TTYPort {
    fn as_raw_fd(&self) -> RawFd {
        self.fd
    }
}

impl IntoRawFd for TTYPort {
    fn into_raw_fd(self) -> RawFd {
        // Pull just the file descriptor out. We also prevent the destructor
        // from being run by calling `mem::forget`. If we didn't do this, the
        // port would be closed, which would make `into_raw_fd` unusable.
        let TTYPort { fd, .. } = self;
        mem::forget(self);
        fd
    }
}

impl FromRawFd for TTYPort {
    unsafe fn from_raw_fd(fd: RawFd) -> Self {
        // Try to set exclusive, as is the default setting.  Catch errors.. this method MUST
        // return a TTYPort so we'll just indicate non-exclusive on an error here.
        let exclusive = match ioctl::tiocexcl(fd) {
            Ok(_) => true,
            Err(_) => false,
        };

        // It is not trivial to get the file path corresponding to a file descriptor.
        // We'll punt on it and set it to `None` here.
        TTYPort {
            fd,
            timeout: Duration::from_millis(100),
            exclusive,
            port_name: None,
            // On Mac & iOS we can't read the baud rate, so we'll set it to 0 indicating that it's
            // unknown.
        }
    }
}

impl io::Read for TTYPort {
    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        if let Err(e) = super::poll::wait_read_fd(self.fd, self.timeout) {
            return Err(io::Error::from(::Error::from(e)));
        }

        match nix::unistd::read(self.fd, buf) {
            Ok(n) => Ok(n),
            Err(e) => Err(io::Error::from(::Error::from(e))),
        }
    }
}

impl io::Write for TTYPort {
    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
        if let Err(e) = super::poll::wait_write_fd(self.fd, self.timeout) {
            return Err(io::Error::from(::Error::from(e)));
        }

        match nix::unistd::write(self.fd, buf) {
            Ok(n) => Ok(n),
            Err(e) => Err(io::Error::from(::Error::from(e))),
        }
    }

    fn flush(&mut self) -> io::Result<()> {
        nix::sys::termios::tcdrain(self.fd)
            .map_err(|_| io::Error::new(io::ErrorKind::Other, "flush failed"))
    }
}

impl SerialPort for TTYPort {
    fn name(&self) -> Option<String> {
        self.port_name.clone()
    }

    /// Returns a struct with all port settings
    // FIXME: Change this to only use a single termios read & write
    fn settings(&self) -> SerialPortSettings {
        SerialPortSettings {
            baud_rate: self.baud_rate().expect("Couldn't retrieve baud rate"),
            data_bits: self.data_bits().expect("Couldn't retrieve data bits"),
            flow_control: self.flow_control().expect("Couldn't retrieve flow control"),
            parity: self.parity().expect("Couldn't retrieve parity"),
            stop_bits: self.stop_bits().expect("Couldn't retrieve stop bits"),
            timeout: self.timeout,
        }
    }

    /// Returns the port's baud rate
    ///
    /// On some platforms this will be the actual device baud rate, which may differ from the
    /// desired baud rate.
    #[cfg(
        any(
            target_os = "android",
            all(
                target_os = "linux",
                not(any(target_env = "musl", target_arch = "powerpc", target_arch = "powerpc64"))
            )
        )
    )]
    fn baud_rate(&self) -> ::Result<u32> {
        let termios2 = ioctl::tcgets2(self.fd)?;

        assert!(termios2.c_ospeed == termios2.c_ispeed);

        Ok(termios2.c_ospeed as u32)
    }

    /// Returns the port's baud rate
    ///
    /// On some platforms this will be the actual device baud rate, which may differ from the
    /// desired baud rate.
    #[cfg(
        any(
            target_os = "dragonflybsd",
            target_os = "freebsd",
            target_os = "ios",
            target_os = "macos",
            target_os = "netbsd",
            target_os = "openbsd"
        )
    )]
    fn baud_rate(&self) -> ::Result<u32> {
        let termios = self.get_termios()?;

        let ospeed = unsafe { libc::cfgetospeed(&termios) };
        let ispeed = unsafe { libc::cfgetispeed(&termios) };

        assert!(ospeed == ispeed);

        Ok(ospeed as u32)
    }

    /// Returns the port's baud rate
    ///
    /// On some platforms this will be the actual device baud rate, which may differ from the
    /// desired baud rate.
    #[cfg(
        all(
            target_os = "linux",
            any(target_env = "musl", target_arch = "powerpc", target_arch = "powerpc64")
        )
    )]
    fn baud_rate(&self) -> ::Result<u32> {
        use self::libc::{B1000000, B1152000, B1500000, B2000000, B2500000, B3000000, B3500000,
                         B4000000, B460800, B500000, B576000, B921600};
        use self::libc::{B110, B115200, B1200, B134, B150, B1800, B19200, B200, B230400, B2400,
                         B300, B38400, B4800, B50, B57600, B600, B75, B9600};

        let termios = self.get_termios()?;
        let ospeed = unsafe { libc::cfgetospeed(&termios) };
        let ispeed = unsafe { libc::cfgetispeed(&termios) };

        assert!(ospeed == ispeed);

        let res: u32 = match ospeed {
            B50 => 50,
            B75 => 75,
            B110 => 110,
            B134 => 134,
            B150 => 150,
            B200 => 200,
            B300 => 300,
            B600 => 600,
            B1200 => 1200,
            B1800 => 1800,
            B2400 => 2400,
            B4800 => 4800,
            B9600 => 9600,
            B19200 => 19_200,
            B38400 => 38_400,
            B57600 => 57_600,
            B115200 => 115_200,
            B230400 => 230_400,
            B460800 => 460_800,
            B500000 => 500_000,
            B576000 => 576_000,
            B921600 => 921_600,
            B1000000 => 1_000_000,
            B1152000 => 1_152_000,
            B1500000 => 1_500_000,
            B2000000 => 2_000_000,
            B2500000 => 2_500_000,
            B3000000 => 3_000_000,
            B3500000 => 3_500_000,
            B4000000 => 4_000_000,
            _ => unreachable!(),
        };

        Ok(res)
    }

    fn data_bits(&self) -> ::Result<DataBits> {
        let termios = self.get_termios()?;
        match termios.c_cflag & libc::CSIZE {
            libc::CS8 => Ok(DataBits::Eight),
            libc::CS7 => Ok(DataBits::Seven),
            libc::CS6 => Ok(DataBits::Six),
            libc::CS5 => Ok(DataBits::Five),
            _ => Err(Error::new(
                ErrorKind::Unknown,
                "Invalid data bits setting encountered",
            )),
        }
    }

    fn flow_control(&self) -> ::Result<FlowControl> {
        let termios = self.get_termios()?;
        if termios.c_cflag & libc::CRTSCTS == libc::CRTSCTS {
            Ok(FlowControl::Hardware)
        } else if termios.c_iflag & (libc::IXON | libc::IXOFF) == (libc::IXON | libc::IXOFF) {
            Ok(FlowControl::Software)
        } else {
            Ok(FlowControl::None)
        }
    }

    fn parity(&self) -> ::Result<Parity> {
        let termios = self.get_termios()?;
        if termios.c_cflag & libc::PARENB == libc::PARENB {
            if termios.c_cflag & libc::PARODD == libc::PARODD {
                Ok(Parity::Odd)
            } else {
                Ok(Parity::Even)
            }
        } else {
            Ok(Parity::None)
        }
    }

    fn stop_bits(&self) -> ::Result<StopBits> {
        let termios = self.get_termios()?;
        if termios.c_cflag & libc::CSTOPB == libc::CSTOPB {
            Ok(StopBits::Two)
        } else {
            Ok(StopBits::One)
        }
    }

    fn timeout(&self) -> Duration {
        self.timeout
    }

    // FIXME: Make this read & write the termios struct only once
    fn set_all(&mut self, settings: &SerialPortSettings) -> ::Result<()> {
        self.set_baud_rate(settings.baud_rate)?;
        self.set_data_bits(settings.data_bits)?;
        self.set_flow_control(settings.flow_control)?;
        self.set_parity(settings.parity)?;
        self.set_stop_bits(settings.stop_bits)?;
        self.set_timeout(settings.timeout)?;

        Ok(())
    }

    #[cfg(
        any(
            target_os = "android",
            all(
                target_os = "linux",
                not(any(target_env = "musl", target_arch = "powerpc", target_arch = "powerpc64"))
            )
        )
    )]
    fn set_baud_rate(&mut self, baud_rate: u32) -> ::Result<()> {
        let mut termios2 = ioctl::tcgets2(self.fd)?;
        termios2.c_cflag &= !nix::libc::CBAUD;
        termios2.c_cflag |= nix::libc::BOTHER;
        termios2.c_ispeed = baud_rate;
        termios2.c_ospeed = baud_rate;

        ioctl::tcsets2(self.fd, &termios2)
    }

    // BSDs use the baud rate as the constant value so there's no translation necessary
    #[cfg(
        any(
            target_os = "dragonflybsd",
            target_os = "freebsd",
            target_os = "macos",
            target_os = "netbsd",
            target_os = "ios",
            target_os = "openbsd"
        )
    )]
    fn set_baud_rate(&mut self, baud_rate: u32) -> ::Result<()> {
        let mut termios = self.get_termios()?;
        let res = unsafe { libc::cfsetspeed(&mut termios, baud_rate.into()) };
        nix::errno::Errno::result(res)?;
        self.set_termios(&termios)
    }

    #[cfg(
        all(
            target_os = "linux",
            any(target_env = "musl", target_arch = "powerpc", target_arch = "powerpc64")
        )
    )]
    fn set_baud_rate(&mut self, baud_rate: u32) -> ::Result<()> {
        use self::libc::{B1000000, B1152000, B1500000, B2000000, B2500000, B3000000, B3500000,
                         B4000000, B460800, B500000, B576000, B921600};
        use self::libc::{B110, B115200, B1200, B134, B150, B1800, B19200, B200, B230400, B2400,
                         B300, B38400, B4800, B50, B57600, B600, B75, B9600};

        let mut termios = self.get_termios()?;

        let baud_rate = match baud_rate {
            50 => B50,
            75 => B75,
            110 => B110,
            134 => B134,
            150 => B150,
            200 => B200,
            300 => B300,
            600 => B600,
            1200 => B1200,
            1800 => B1800,
            2400 => B2400,
            4800 => B4800,
            9600 => B9600,
            19_200 => B19200,
            38_400 => B38400,
            57_600 => B57600,
            115_200 => B115200,
            230_400 => B230400,
            460_800 => B460800,
            500_000 => B500000,
            576_000 => B576000,
            921_600 => B921600,
            1_000_000 => B1000000,
            1_152_000 => B1152000,
            1_500_000 => B1500000,
            2_000_000 => B2000000,
            2_500_000 => B2500000,
            3_000_000 => B3000000,
            3_500_000 => B3500000,
            4_000_000 => B4000000,
            _ => return Err(Error::new(ErrorKind::InvalidInput, "invalid baud rate")),
        };
        let res = unsafe { libc::cfsetspeed(&mut termios, baud_rate) };
        nix::errno::Errno::result(res)?;
        self.set_termios(&termios)
    }

    fn set_flow_control(&mut self, flow_control: FlowControl) -> ::Result<()> {
        let mut termios = self.get_termios()?;
        match flow_control {
            FlowControl::None => {
                termios.c_iflag &= !(libc::IXON | libc::IXOFF);
                termios.c_cflag &= !libc::CRTSCTS;
            }
            FlowControl::Software => {
                termios.c_iflag |= libc::IXON | libc::IXOFF;
                termios.c_cflag &= !libc::CRTSCTS;
            }
            FlowControl::Hardware => {
                termios.c_iflag &= !(libc::IXON | libc::IXOFF);
                termios.c_cflag |= libc::CRTSCTS;
            }
        };
        self.set_termios(&termios)
    }

    fn set_parity(&mut self, parity: Parity) -> ::Result<()> {
        let mut termios = self.get_termios()?;
        match parity {
            Parity::None => {
                termios.c_cflag &= !(libc::PARENB | libc::PARODD);
                termios.c_iflag &= !libc::INPCK;
                termios.c_iflag |= libc::IGNPAR;
            }
            Parity::Odd => {
                termios.c_cflag |= libc::PARENB | libc::PARODD;
                termios.c_iflag |= libc::INPCK;
                termios.c_iflag &= !libc::IGNPAR;
            }
            Parity::Even => {
                termios.c_cflag &= !libc::PARODD;
                termios.c_cflag |= libc::PARENB;
                termios.c_iflag |= libc::INPCK;
                termios.c_iflag &= !libc::IGNPAR;
            }
        };
        self.set_termios(&termios)
    }

    fn set_data_bits(&mut self, data_bits: DataBits) -> ::Result<()> {
        let size = match data_bits {
            DataBits::Five => libc::CS5,
            DataBits::Six => libc::CS6,
            DataBits::Seven => libc::CS7,
            DataBits::Eight => libc::CS8,
        };

        let mut termios = self.get_termios()?;
        termios.c_cflag &= !libc::CSIZE;
        termios.c_cflag |= size;
        self.set_termios(&termios)
    }

    fn set_stop_bits(&mut self, stop_bits: StopBits) -> ::Result<()> {
        let mut termios = self.get_termios()?;
        match stop_bits {
            StopBits::One => termios.c_cflag &= !libc::CSTOPB,
            StopBits::Two => termios.c_cflag |= libc::CSTOPB,
        };
        self.set_termios(&termios)
    }

    fn set_timeout(&mut self, timeout: Duration) -> ::Result<()> {
        self.timeout = timeout;
        Ok(())
    }

    fn write_request_to_send(&mut self, level: bool) -> ::Result<()> {
        self.set_pin(SerialLines::REQUEST_TO_SEND, level)
    }

    fn write_data_terminal_ready(&mut self, level: bool) -> ::Result<()> {
        self.set_pin(SerialLines::DATA_TERMINAL_READY, level)
    }

    fn read_clear_to_send(&mut self) -> ::Result<bool> {
        self.read_pin(SerialLines::CLEAR_TO_SEND)
    }

    fn read_data_set_ready(&mut self) -> ::Result<bool> {
        self.read_pin(SerialLines::DATA_SET_READY)
    }

    fn read_ring_indicator(&mut self) -> ::Result<bool> {
        self.read_pin(SerialLines::RING)
    }

    fn read_carrier_detect(&mut self) -> ::Result<bool> {
        self.read_pin(SerialLines::DATA_CARRIER_DETECT)
    }

    fn bytes_to_read(&self) -> ::Result<u32> {
        ioctl::fionread(self.fd)
    }

    fn bytes_to_write(&self) -> ::Result<u32> {
        ioctl::tiocoutq(self.fd)
    }

    fn clear(&self, buffer_to_clear: ::ClearBuffer) -> ::Result<()> {
        let buffer_id = match buffer_to_clear {
            ::ClearBuffer::Input => libc::TCIFLUSH,
            ::ClearBuffer::Output => libc::TCOFLUSH,
            ::ClearBuffer::All => libc::TCIOFLUSH,
        };

        let res = unsafe { nix::libc::tcflush(self.fd, buffer_id) };

        nix::errno::Errno::result(res)
            .map(|_| ())
            .map_err(|e| e.into())
    }

    fn try_clone(&self) -> ::Result<Box<SerialPort>> {
        let fd_cloned: i32 = fcntl(self.fd, nix::fcntl::F_DUPFD(self.fd))?;
        Ok(Box::new(TTYPort {
            fd: fd_cloned,
            exclusive: self.exclusive,
            port_name: self.port_name.clone(),
            timeout: self.timeout,
        }))
    }
}

/// Retrieves the udev property value named by `key`. If the value exists, then it will be
/// converted to a String, otherwise None will be returned.
#[cfg(all(target_os = "linux", not(target_env = "musl"), feature = "libudev"))]
fn udev_property_as_string(d: &libudev::Device, key: &str) -> Option<String> {
    if let Some(s) = d.property_value(key).and_then(OsStr::to_str) {
        Some(s.to_string())
    } else {
        None
    }
}

/// Retrieves the udev property value named by `key`. This function assumes that the retrieved
/// string is comprised of hex digits and the integer value of this will be returned as  a u16.
/// If the property value doesn't exist or doesn't contain valid hex digits, then an error
/// will be returned.
#[cfg(all(target_os = "linux", not(target_env = "musl"), feature = "libudev"))]
fn udev_hex_property_as_u16(d: &libudev::Device, key: &str) -> ::Result<u16> {
    if let Some(hex_str) = d.property_value(key).and_then(OsStr::to_str) {
        if let Ok(num) = u16::from_str_radix(hex_str, 16) {
            Ok(num)
        } else {
            Err(Error::new(ErrorKind::Unknown, "value not hex string"))
        }
    } else {
        Err(Error::new(ErrorKind::Unknown, "key not found"))
    }
}

#[cfg(all(target_os = "linux", not(target_env = "musl"), feature = "libudev"))]
fn port_type(d: &libudev::Device) -> ::Result<::SerialPortType> {
    match d.property_value("ID_BUS").and_then(OsStr::to_str) {
        Some("usb") => {
            let serial_number = udev_property_as_string(d, "ID_SERIAL_SHORT");
            Ok(SerialPortType::UsbPort(UsbPortInfo {
                vid: udev_hex_property_as_u16(d, "ID_VENDOR_ID")?,
                pid: udev_hex_property_as_u16(d, "ID_MODEL_ID")?,
                serial_number,
                manufacturer: udev_property_as_string(d, "ID_VENDOR"),
                product: udev_property_as_string(d, "ID_MODEL"),
            }))
        }
        Some("pci") => Ok(::SerialPortType::PciPort),
        _ => Ok(::SerialPortType::Unknown),
    }
}

#[cfg(target_os = "macos")]
fn get_parent_device_by_type(
    device: io_object_t,
    parent_type: *const c_char,
) -> Option<io_registry_entry_t> {
    let parent_type = unsafe { CStr::from_ptr(parent_type) };
    use mach::kern_return::KERN_SUCCESS;
    let mut device = device;
    loop {
        let mut class_name: [c_char; 128] = unsafe { mem::uninitialized() };
        unsafe { IOObjectGetClass(device, &mut class_name[0]) };
        let name = unsafe { CStr::from_ptr(&class_name[0]) };
        if name == parent_type {
            return Some(device);
        }
        let mut parent: io_registry_entry_t = unsafe { mem::uninitialized() };
        if unsafe {
            IORegistryEntryGetParentEntry(device, kIOServiceClass(), &mut parent) != KERN_SUCCESS
        } {
            return None;
        }
        device = parent;
    }
}

#[cfg(target_os = "macos")]
#[allow(non_upper_case_globals)]
/// Returns a specific property of the given device as an integer.
fn get_int_property(
    device_type: io_registry_entry_t,
    property: &str,
    cf_number_type: CFNumberType,
) -> Option<u32> {
    unsafe {
        let prop_str = CString::new(property).unwrap();
        let key = CFStringCreateWithCString(
            kCFAllocatorDefault,
            prop_str.as_ptr(),
            kCFStringEncodingUTF8,
        );
        let container = IORegistryEntryCreateCFProperty(device_type, key, kCFAllocatorDefault, 0);
        if container.is_null() {
            return None;
        }
        let num = match cf_number_type {
            kCFNumberSInt16Type => {
                let mut num: u16 = 0;
                let num_ptr: *mut c_void = &mut num as *mut _ as *mut c_void;
                CFNumberGetValue(container as CFNumberRef, cf_number_type, num_ptr);
                Some(num as u32)
            }
            kCFNumberSInt32Type => {
                let mut num: u32 = 0;
                let num_ptr: *mut c_void = &mut num as *mut _ as *mut c_void;
                CFNumberGetValue(container as CFNumberRef, cf_number_type, num_ptr);
                Some(num)
            }
            _ => None,
        };
        CFRelease(container);

        num
    }
}

#[cfg(target_os = "macos")]
/// Returns a specific property of the given device as a string.
fn get_string_property(device_type: io_registry_entry_t, property: &str) -> Option<String> {
    unsafe {
        let prop_str = CString::new(property).unwrap();
        let key = CFStringCreateWithCString(
            kCFAllocatorDefault,
            prop_str.as_ptr(),
            kCFStringEncodingUTF8,
        );
        let container = IORegistryEntryCreateCFProperty(device_type, key, kCFAllocatorDefault, 0);
        if container.is_null() {
            return None;
        }

        let str_ptr = CFStringGetCStringPtr(container as CFStringRef, kCFStringEncodingMacRoman);
        if str_ptr.is_null() {
            CFRelease(container);
            return None;
        }
        let opt_str = CStr::from_ptr(str_ptr).to_str().ok().map(String::from);

        CFRelease(container);

        opt_str
    }
}

#[cfg(target_os = "macos")]
/// Determine the serial port type based on the service object (like that returned by
/// `IOIteratorNext`). Specific properties are extracted for USB devices.
fn port_type(service: io_object_t) -> ::SerialPortType {
    let bluetooth_device_class_name = b"IOBluetoothSerialClient\0".as_ptr() as *const c_char;
    if let Some(usb_device) = get_parent_device_by_type(service, kIOUSBDeviceClassName()) {
        SerialPortType::UsbPort(UsbPortInfo {
            vid: get_int_property(usb_device, "idVendor", kCFNumberSInt16Type).unwrap_or_default()
                as u16,
            pid: get_int_property(usb_device, "idProduct", kCFNumberSInt16Type).unwrap_or_default()
                as u16,
            serial_number: get_string_property(usb_device, "USB Serial Number"),
            manufacturer: get_string_property(usb_device, "USB Vendor Name"),
            product: get_string_property(usb_device, "USB Product Name"),
        })
    } else if get_parent_device_by_type(service, bluetooth_device_class_name).is_some() {
        ::SerialPortType::BluetoothPort
    } else {
        ::SerialPortType::PciPort
    }
}

cfg_if! {
    if #[cfg(target_os = "macos")] {
        /// Scans the system for serial ports and returns a list of them.
        /// The `SerialPortInfo` struct contains the name of the port which can be used for opening it.
        pub fn available_ports() -> ::Result<Vec<SerialPortInfo>> {
            use cf::*;
            use mach::kern_return::KERN_SUCCESS;
            use mach::port::{mach_port_t, MACH_PORT_NULL};
            use IOKit_sys::*;

            let mut vec = Vec::new();
            unsafe {
                // Create a dictionary for specifying the search terms against the IOService
                let classes_to_match = IOServiceMatching(kIOSerialBSDServiceValue());
                if classes_to_match.is_null() {
                    return Err(Error::new(
                        ErrorKind::Unknown,
                        "IOServiceMatching returned a NULL dictionary.",
                    ));
                }

                // Populate the search dictionary with a single key/value pair indicating that we're
                // searching for serial devices matching the RS232 device type.
                let key = CFStringCreateWithCString(
                    kCFAllocatorDefault,
                    kIOSerialBSDTypeKey(),
                    kCFStringEncodingUTF8,
                );
                if key.is_null() {
                    return Err(Error::new(
                        ErrorKind::Unknown,
                        "Failed to allocate key string.",
                    ));
                }
                let value = CFStringCreateWithCString(
                    kCFAllocatorDefault,
                    kIOSerialBSDAllTypes(),
                    kCFStringEncodingUTF8,
                );
                if value.is_null() {
                    return Err(Error::new(
                        ErrorKind::Unknown,
                        "Failed to allocate value string.",
                    ));
                }
                CFDictionarySetValue(classes_to_match, key as CFTypeRef, value as CFTypeRef);

                // Get an interface to IOKit
                let mut master_port: mach_port_t = MACH_PORT_NULL;
                let mut kern_result = IOMasterPort(MACH_PORT_NULL, &mut master_port);
                if kern_result != KERN_SUCCESS {
                    return Err(Error::new(
                        ErrorKind::Unknown,
                        format!("ERROR: {}", kern_result),
                    ));
                }

                // Run the search.
                let mut matching_services: io_iterator_t = mem::uninitialized();
                kern_result = IOServiceGetMatchingServices(
                    kIOMasterPortDefault,
                    classes_to_match,
                    &mut matching_services,
                );
                if kern_result != KERN_SUCCESS {
                    return Err(Error::new(
                        ErrorKind::Unknown,
                        format!("ERROR: {}", kern_result),
                    ));
                }

                loop {
                    // Grab the next result.
                    let modem_service = IOIteratorNext(matching_services);

                    // Break out if we've reached the end of the iterator
                    if modem_service == MACH_PORT_NULL {
                        break;
                    }

                    // Fetch all properties of the current search result item.
                    let mut props = mem::uninitialized();
                    let result = IORegistryEntryCreateCFProperties(
                        modem_service,
                        &mut props,
                        kCFAllocatorDefault,
                        0,
                    );
                    if result == KERN_SUCCESS {
                        // We only care about the IODialinDevice, which is the device path for this port.
                        let key = CString::new("IODialinDevice").unwrap();
                        let key_cfstring = CFStringCreateWithCString(
                            kCFAllocatorDefault,
                            key.as_ptr(),
                            kCFStringEncodingUTF8,
                        );
                        let value = CFDictionaryGetValue(props, key_cfstring as *const c_void);

                        let type_id = CFGetTypeID(value);
                        if type_id == CFStringGetTypeID() {
                            let mut buf = Vec::with_capacity(256);

                            CFStringGetCString(
                                value as CFStringRef,
                                buf.as_mut_ptr(),
                                256,
                                kCFStringEncodingUTF8,
                            );
                            let path = CStr::from_ptr(buf.as_ptr()).to_string_lossy();
                            vec.push(SerialPortInfo {
                                port_name: path.to_string(),
                                port_type: port_type(modem_service),
                            });
                        } else {
                            return Err(Error::new(
                                ErrorKind::Unknown,
                                "Found invalid type for TypeID",
                            ));
                        }
                    } else {
                        return Err(Error::new(ErrorKind::Unknown, format!("ERROR: {}", result)));
                    }

                    // Clean up after we're done processing htis result
                    IOObjectRelease(modem_service);
                }
            }
            Ok(vec)
        }
    } else if #[cfg(all(target_os = "linux", not(target_env = "musl"), feature = "libudev"))] {
        /// Scans the system for serial ports and returns a list of them.
        /// The `SerialPortInfo` struct contains the name of the port
        /// which can be used for opening it.
        pub fn available_ports() -> ::Result<Vec<SerialPortInfo>> {
            let mut vec = Vec::new();
            if let Ok(context) = libudev::Context::new() {
                let mut enumerator = libudev::Enumerator::new(&context)?;
                enumerator.match_subsystem("tty")?;
                let devices = enumerator.scan_devices()?;
                for d in devices {
                    if let Some(p) = d.parent() {
                        if let Some(devnode) = d.devnode() {
                            if let Some(path) = devnode.to_str() {
                                if let Some(driver) = p.driver() {
                                    if driver == "serial8250"
                                        && TTYPort::open(devnode, &Default::default()).is_err()
                                    {
                                        continue;
                                    }
                                }
                                // Stop bubbling up port_type errors here so problematic ports are just
                                // skipped instead of causing no ports to be returned.
                                if let Ok(pt) = port_type(&d) {
                                    vec.push(SerialPortInfo {
                                        port_name: String::from(path),
                                        port_type: pt,
                                    });
                                }
                            }
                        }
                    }
                }
            }
            Ok(vec)
        }
    } else if #[cfg(all(target_os = "linux", not(target_env = "musl")))] {
        /// Enumerating serial ports on non-Linux POSIX platforms is disabled by disabled the "libudev"
        /// default feature.
        pub fn available_ports() -> ::Result<Vec<SerialPortInfo>> {
            Err(Error::new(
                ErrorKind::Unknown,
                "Serial port enumeration disabled (to enable compile with the 'libudev' feature)",
            ))
        }
    } else if #[cfg(target_os = "freebsd")] {
        /// Scans the system for serial ports and returns a list of them.
        /// The `SerialPortInfo` struct contains the name of the port
        /// which can be used for opening it.
        pub fn available_ports() -> ::Result<Vec<SerialPortInfo>> {
            let mut vec = Vec::new();
            let dev_path = Path::new("/dev/");
            for path in dev_path.read_dir()? {
                let path = path?;
                let filename = path.file_name();
                let filename_string = filename.to_string_lossy();
                if filename_string.starts_with("cuaU") || filename_string.starts_with("cuau") || filename_string.starts_with("cuad") {
                    if !filename_string.ends_with(".init") && !filename_string.ends_with(".lock") {
                        vec.push(SerialPortInfo {
                            port_name: path.path().to_string_lossy().to_string(),
                            port_type: ::SerialPortType::Unknown,
                        });
                    }
                }
            }
            Ok(vec)
        }
    } else {
        /// Enumerating serial ports on this platform is not supported
        pub fn available_ports() -> ::Result<Vec<SerialPortInfo>> {
            Err(Error::new(
                ErrorKind::Unknown,
                "Not implemented for this OS",
            ))
        }
    }
}

#[test]
fn test_ttyport_into_raw_fd() {
    // `master` must be used here as Dropping it causes slave to be deleted by the OS.
    // TODO: Convert this to a statement-level attribute once
    //       https://github.com/rust-lang/rust/issues/15701 is on stable.
    // FIXME: Create a mutex across all tests for using `TTYPort::pair()` as it's not threadsafe
    #![allow(unused_variables)]
    let (master, slave) = TTYPort::pair().expect("Unable to create ptty pair");

    // First test with the master
    let master_fd = master.into_raw_fd();
    let mut termios = unsafe { mem::uninitialized() };
    let res = unsafe { nix::libc::tcgetattr(master_fd, &mut termios) };
    if res != 0 {
        close(master_fd);
        panic!("tcgetattr on the master port failed");
    }

    // And then the slave
    let slave_fd = slave.into_raw_fd();
    let res = unsafe { nix::libc::tcgetattr(slave_fd, &mut termios) };
    if res != 0 {
        close(slave_fd);
        panic!("tcgetattr on the master port failed");
    }
    close(master_fd);
    close(slave_fd);
}