I'm attempting to create a streaming reqwest::Body from a file on my filesystem and I'm using Tokio, so it's async.

I'm getting reference issues as I have to borrow the buffer as mutable in my core stream loop and immutable in the body of the loop to read out of it.

Example code:

async fn file(path: PathBuf) -> Result<impl Stream<Item=Result<Bytes, anyhow::Error>>, anyhow::Error> {
    let stream = try_stream! {
        let mut f = tokio::fs::File::open(file).await.unwrap();

        let mut buf = BytesMut::with_capacity(8 * 1024);

        while let bytes_read = f.read(buf.as_mut()).await? {
            if bytes_read == 0 { break }

            yield Bytes::from(&buf[..bytes_read]);
        }
    }

    Ok(stream)
}

I don't see a way to make buf non-mutable, as the read function needs a mutable reference, and I must be able to read from it in order to create a Bytes from it.

How should I go about doing this? Are there any examples out there for this? This seems like a common thing to do and I'm not seeing a path forward. I suppose I could wrap it all in a Mutex or a RwLock but that feels like overkill here.

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