Method write

src/io/streams.rs:252–281

Asynchronously write to the output stream. This method is the same as [`AsyncWrite::write`], but doesn't require a `&mut self`. Awaits for write readiness, and then performs at most one write to the output stream. Returns how much of the argument `buf` was written, or a `std::io::Error` indicating either an error returned by the stream write using the debug string provided by the WASI error, or e

(&self, buf: &[u8])

    /// using the debug string provided by the WASI error, or else that the,
    /// indicated by `std::io::ErrorKind::ConnectionReset`.
    pub async fn write(&self, buf: &[u8]) -> std::io::Result<usize> {
        // Loops at most twice.
        loop {
            match self.stream.check_write() {
                Ok(0) => {
                    self.ready().await;
                    // Next loop guaranteed to have nonzero check_write, or error.
                    continue;
                }
                Ok(some) => {
                    let writable = some.try_into().unwrap_or(usize::MAX).min(buf.len());
                    match self.stream.write(&buf[0..writable]) {
                        Ok(()) => return Ok(writable),
                        Err(StreamError::Closed) => {
                            return Err(std::io::Error::from(std::io::ErrorKind::ConnectionReset));
                        }
                        Err(StreamError::LastOperationFailed(err)) => {
                            return Err(std::io::Error::other(err.to_debug_string()));
                        }
                    }
                }
                Err(StreamError::Closed) => {
                    return Err(std::io::Error::from(std::io::ErrorKind::ConnectionReset));
                }
                Err(StreamError::LastOperationFailed(err)) => {
                    return Err(std::io::Error::other(err.to_debug_string()));
                }
            }
        }
    }

    /// Asynchronously write to the output stream. This method is the same as
    /// [`AsyncWrite::write_all`], but doesn't require a `&mut self`.