fix(http): fix encoding when buffer is full

src/http/conn.rs

@@ -803,6 +803,8 @@ mod tests {
 
     #[test]
     fn test_conn_body_write_length() {
+        extern crate pretty_env_logger;
+        let _ = pretty_env_logger::init();
         let _: Result<(), ()> = future::lazy(|| {
             let io = AsyncIo::new_buf(vec![], 0);
             let mut conn = Conn::<_, http::Chunk, ServerTransaction>::new(io, Default::default());

src/http/h1/encode.rs

@@ -54,9 +54,12 @@ impl Encoder {
                 chunked.encode(w, msg)
             },
             Kind::Length(ref mut remaining) => {
+                if msg.is_empty() {
+                    return Ok(0);
+                }
                 let n = {
                     let max = cmp::min(*remaining as usize, msg.len());
-                    trace!("sized write, len = {}", max);
+                    trace!("sized write, len = {}, remaining = {}", max, remaining);
                     let slice = &msg[..max];
 
                     try!(w.write_atomic(&[slice]))

src/http/io.rs

@@ -130,7 +130,12 @@ impl<T: AsyncRead + AsyncWrite> Buffered<T> {
 
 impl<T: Write> Write for Buffered<T> {
     fn write(&mut self, data: &[u8]) -> io::Result<usize> {
-        Ok(self.write_buf.buffer(data))
+        let n = self.write_buf.buffer(data);
+        if n == 0 {
+            Err(io::Error::from(io::ErrorKind::WouldBlock))
+        } else {
+            Ok(n)
+        }
     }
 
     fn flush(&mut self) -> io::Result<()> {