Fix the issue when the response body exceeds 4096 bytes

test-programs/src/bin/server_large_body.rs

@@ -0,0 +1,10 @@
+use waki::{handler, ErrorCode, Request, Response};
+
+#[handler]
+fn hello(_: Request) -> Result<Response, ErrorCode> {
+    let buffer = [0; 5000];
+    Response::builder().body(buffer).build()
+}
+
+// required since this file is built as a `bin`
+fn main() {}

waki/src/response.rs

@@ -106,7 +106,11 @@ pub fn handle_response(response_out: ResponseOutparam, response: Response) {
     let body = response.body.bytes().unwrap();
     if !body.is_empty() {
         let out = outgoing_body.write().unwrap();
-        out.blocking_write_and_flush(&body).unwrap();
+        // `blocking-write-and-flush` writes up to 4096 bytes
+        let chunks = body.chunks(4096);
+        for chunk in chunks {
+            out.blocking_write_and_flush(chunk).unwrap();
+        }
     }
 
     OutgoingBody::finish(outgoing_body, None).unwrap();

waki/tests/all/server.rs

@@ -30,6 +30,19 @@ async fn json() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test(flavor = "multi_thread")]
+async fn large_body() -> Result<()> {
+    let req = hyper::Request::builder()
+        .uri("http://localhost")
+        .body(body::empty())?;
+
+    let resp = run_wasi_http(test_programs_artifacts::SERVER_LARGE_BODY_COMPONENT, req).await??;
+    let body = resp.into_body().to_bytes();
+    assert_eq!(body.len(), 5000);
+
+    Ok(())
+}
+
 #[tokio::test(flavor = "multi_thread")]
 async fn multipart_form() -> Result<()> {
     let req = hyper::Request::builder()