update: simplify and fix a latent issue with bytestream's streaming impl (#1461)

meta = { "breaking" = false, "tada" = false, "bug" = true }

author = "rcoh"

[[smithy-rs]]

message = """

Fix a potential bug with `ByteStream`'s implementation of `futures_core::stream::Stream` and add helpful error messages

for users on 32-bit systems that try to stream HTTP bodies larger than 4.29Gb.

"""

references = ["smithy-rs#1460"]

meta = { "breaking" = false, "tada" = false, "bug" = false }

author = "Velfi"

[[aws-sdk-rust]]

message = "Add `Debug` implementation to several types in `aws-config`"

references = ["smithy-rs#1421"]

    }

}

const SIZE_HINT_32_BIT_PANIC_MESSAGE: &str = r#"

You're running a 32-bit system and this stream's length is too large to be represented with a usize.

Please limit stream length to less than 4.294Gb or run this program on a 64-bit computer architecture.

"#;

impl<B> futures_core::stream::Stream for Inner<B>

where

    B: http_body::Body,

    B: http_body::Body<Data = Bytes>,

{

    type Item = Result<Bytes, B::Error>;

    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {

        match self.project().body.poll_data(cx) {

            Poll::Ready(Some(Ok(mut data))) => {

                let len = data.chunk().len();

                let bytes = data.copy_to_bytes(len);

                Poll::Ready(Some(Ok(bytes)))

            }

            Poll::Ready(None) => Poll::Ready(None),

            Poll::Ready(Some(Err(e))) => Poll::Ready(Some(Err(e))),

            Poll::Pending => Poll::Pending,

        }

        self.project().body.poll_data(cx)

    }

    fn size_hint(&self) -> (usize, Option<usize>) {

        let size_hint = http_body::Body::size_hint(&self.body);

        (

            size_hint.lower() as usize,

            size_hint.upper().map(|u| u as usize),

        )

        let lower = size_hint.lower().try_into();

        let upper = size_hint.upper().map(|u| u.try_into()).transpose();

        match (lower, upper) {

            (Ok(lower), Ok(upper)) => (lower, upper),

            (Err(_), _) | (_, Err(_)) => {

                panic!("{}", SIZE_HINT_32_BIT_PANIC_MESSAGE)

            }

        }

    }

}