mid coding commit

core/helpers/src/byte_replacement_reader.rs

@@ -0,0 +1,31 @@
+use std::task::Poll;
+
+use tokio::io::{AsyncRead, ReadBuf};
+
+#[pin_project::pin_project]
+pub struct ByteReplacementReader<R> {
+    pub replace: u8,
+    pub with: u8,
+    #[pin]
+    pub inner: R,
+}
+impl<R: AsyncRead> AsyncRead for ByteReplacementReader<R> {
+    fn poll_read(
+        self: std::pin::Pin<&mut Self>,
+        cx: &mut std::task::Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> std::task::Poll<std::io::Result<()>> {
+        let this = self.project();
+        match this.inner.poll_read(cx, buf) {
+            Poll::Ready(Ok(())) => {
+                for idx in 0..buf.filled().len() {
+                    if buf.filled()[idx] == *this.replace {
+                        buf.filled_mut()[idx] = *this.with;
+                    }
+                }
+                Poll::Ready(Ok(()))
+            }
+            a => a,
+        }
+    }
+}