linux_embedded_hal/
serial.rs

1//! Implementation of [`embedded-hal`] serial traits
2//!
3//! [`embedded-hal`]: https://docs.rs/embedded-hal
4
5use serialport::{SerialPortBuilder, TTYPort};
6use std::fmt;
7use std::io::{ErrorKind as IoErrorKind, Read, Write};
8
9/// Newtype around [`serialport::TTYPort`] that implements
10/// the `embedded-hal` traits.
11pub struct Serial(pub TTYPort);
12
13impl Serial {
14    /// Open a `serialport::TTYPort` by providing the port path and baud rate
15    pub fn open(path: String, baud_rate: u32) -> Result<Serial, serialport::Error> {
16        Ok(Serial(serialport::new(path, baud_rate).open_native()?))
17    }
18
19    /// Open a `serialport::TTYPort` by providing `serialport::SerialPortBuilder`
20    pub fn open_from_builder(builder: SerialPortBuilder) -> Result<Serial, serialport::Error> {
21        Ok(Serial(builder.open_native()?))
22    }
23}
24
25/// Helper to convert std::io::Error to the nb::Error
26fn translate_io_errors(err: std::io::Error) -> nb::Error<SerialError> {
27    match err.kind() {
28        IoErrorKind::WouldBlock | IoErrorKind::TimedOut | IoErrorKind::Interrupted => {
29            nb::Error::WouldBlock
30        }
31        err => nb::Error::Other(SerialError { err }),
32    }
33}
34
35impl embedded_hal_nb::serial::ErrorType for Serial {
36    type Error = SerialError;
37}
38
39impl embedded_hal_nb::serial::Read<u8> for Serial {
40    fn read(&mut self) -> nb::Result<u8, Self::Error> {
41        let mut buffer = [0; 1];
42        let bytes_read = self.0.read(&mut buffer).map_err(translate_io_errors)?;
43        if bytes_read == 1 {
44            Ok(buffer[0])
45        } else {
46            Err(nb::Error::WouldBlock)
47        }
48    }
49}
50
51impl embedded_hal_nb::serial::Write<u8> for Serial {
52    fn write(&mut self, word: u8) -> nb::Result<(), Self::Error> {
53        self.0.write(&[word]).map_err(translate_io_errors)?;
54        Ok(())
55    }
56
57    fn flush(&mut self) -> nb::Result<(), Self::Error> {
58        self.0.flush().map_err(translate_io_errors)
59    }
60}
61
62/// Error type wrapping [io::ErrorKind](IoErrorKind) to implement [embedded_hal::serial::ErrorKind]
63#[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
64pub struct SerialError {
65    err: IoErrorKind,
66}
67
68impl SerialError {
69    /// Fetch inner (concrete) [`IoErrorKind`]
70    pub fn inner(&self) -> &IoErrorKind {
71        &self.err
72    }
73}
74
75impl fmt::Display for SerialError {
76    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
77        write!(f, "{}", self.err)
78    }
79}
80
81impl std::error::Error for SerialError {}
82
83impl embedded_hal_nb::serial::Error for SerialError {
84    #[allow(clippy::match_single_binding)]
85    fn kind(&self) -> embedded_hal_nb::serial::ErrorKind {
86        use embedded_hal_nb::serial::ErrorKind::*;
87        // TODO: match any errors here if we can find any that are relevant
88        Other
89    }
90}
91
92#[cfg(test)]
93mod test {
94    use embedded_hal_nb::serial::{Read, Write};
95    use std::io::{Read as IoRead, Write as IoWrite};
96
97    use super::*;
98
99    fn create_pty_and_serial() -> (std::fs::File, Serial) {
100        let (master, _slave, name) =
101            openpty::openpty(None, None, None).expect("Creating pty failed");
102        let serial = Serial::open(name, 9600).expect("Creating TTYPort failed");
103        (master, serial)
104    }
105
106    #[test]
107    fn create_serial_from_builder() {
108        let (_master, _slave, name) =
109            openpty::openpty(None, None, None).expect("Creating pty failed");
110        let builder = serialport::new(name, 9600);
111        let _serial = Serial::open_from_builder(builder).expect("Creating TTYPort failed");
112    }
113
114    #[test]
115    fn test_empty_read() {
116        let (mut _master, mut serial) = create_pty_and_serial();
117        assert_eq!(Err(nb::Error::WouldBlock), serial.read());
118    }
119
120    #[test]
121    fn test_read() {
122        let (mut master, mut serial) = create_pty_and_serial();
123        master.write_all(&[1]).expect("Write failed");
124        assert_eq!(Ok(1), serial.read());
125    }
126
127    #[test]
128    fn test_write() {
129        let (mut master, mut serial) = create_pty_and_serial();
130        serial.write(2).expect("Write failed");
131        let mut buf = [0; 2];
132        assert_eq!(1, master.read(&mut buf).unwrap());
133        assert_eq!(buf, [2, 0]);
134    }
135}
linux_embedded_hal/serial.rs

linux_embedded_hal/
serial.rs
