Fixed string interpretation with broken UTF-8 characters

Before, if an invalid UTF-8 sequence was decoded, the program would error out. Now, it will decode as much as it and can keep the remaining uninterpreted bytes in its buffer.

src/serial_interface.rs

@@ -6,34 +6,54 @@ use std::{io, str};
 
 use tokio_util::codec::{Decoder, Encoder, Framed};
 
-use bytes::{BufMut, BytesMut};
+use bytes::{BufMut, BytesMut, Buf};
 use console::Term;
 use tokio_serial::SerialPortBuilderExt;
 use tokio_serial::SerialStream;
 
 pub struct LineCodec;
 
+impl LineCodec {
+ fn clean_input(input: &str ) -> String {
+ input.replace('\n', "\r\n")
+ }
+}
+
 impl Decoder for LineCodec {
  type Item = String;
  type Error = io::Error;
 
- fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Self::Item>, Self::Error> {
- if src.is_empty() {
+ fn decode(&mut self, source: &mut BytesMut) -> Result<Option<Self::Item>, Self::Error> {
+ if source.is_empty() {
  return Ok(None);
  }
 
  // Read everything you can, and interpret it as a string.
- // TODO: Note that this can fail if we try to decode in the middle of a multi-byte UTF-8 Character.
- // We could wait for more output, or use this <https://doc.rust-lang.org/stable/core/str/struct.Utf8Error.html#method.valid_up_to>
- let result = match str::from_utf8(src) {
- Ok(s) => {
- let output = s.replace('\n', "\r\n");
+ match str::from_utf8(&source) {
+ Ok(utf8_string) => {
+ let output = LineCodec::clean_input(utf8_string);
+ source.clear();
  Ok(Some(output))
  }
- Err(_) => Err(io::Error::new(io::ErrorKind::Other, "Invalid String")),
- };
- src.clear();
- result
+ Err(error) => {
+ let index = error.valid_up_to();
+
+ if index == 0 {
+ // Returning Some("") makes it so no other bytes are read in. I have no idea why.
+ // If you find a reason why, please edit this comment.
+ return Ok(None);
+ }
+
+ match str::from_utf8(&source[..index]) {
+ Ok(utf8_string) => {
+ let output = LineCodec::clean_input(utf8_string);
+ source.advance(index);
+ Ok(Some(output))
+ },
+ Err(_) => Err(io::Error::new(io::ErrorKind::InvalidData, format!("Couldn't parse input as UTF8. Last valid index: {}. Buffer: {:?}",index,source))),
+ }
+ }
+ }
  }
 }