In the Rust's book final project the code compile and run as expected with cargo run.
However, clippy highlights these commented lines with clippy::unused_io_amount
let mut buffer = [0; 1024];
stream.read(&mut buffer).unwrap(); // clippy: read amount is not handled
// --snip--
stream.write(response.as_bytes()).unwrap(); // clippy: written amount is not handled
stream.flush().unwrap();
The suggest fix is to change read to read_exact and write to write_all. However, when running with this changes I get the following error:
thread '<unnamed>' panicked at 'called `Result::unwrap()` on an `Err` value: Error { kind: UnexpectedEof, message: "failed to fill whole buffer" }', src/main.rs:24:36
How to fix the clippy:: unused_io_amount warning to be able to properly run the rust final project code without any warnings and have it to work as expected?
P.s. in the final project listing write_all is included but the warning for read continues on.
The stream.write(...).unwrap() will return the number of bytes that have been written into the stream. Your warning says that this number is not handled. It means that you should write let bytes_amount = stream.write(...).unwrap(); and then compare bytes_amount with buffer.len().
Why? Because in real life can be a situation when not all data from the buffer were written into the stream. You should handle such situations
The same with the read function.
Why read_exact fails. The read_exact function tries to read bytes to fill a WHOLE buffer but can be a situation the stream ends before the buffer gets filled.