fix(core): Command::output suspend while wait for response

[dyxushuai]

tauri/core/tauri/src/api/process/command.rs

Lines 273 to 286 in 67d7877

	spawn_pipe_reader(
	tx.clone(),
	guard.clone(),
	stdout_reader,
	CommandEvent::Stdout,
	encoding,
	);
	spawn_pipe_reader(
	tx.clone(),
	guard.clone(),
	stderr_reader,
	CommandEvent::Stderr,
	encoding,
	);

These two methods will hold the tx(Sender) and never drop them because the method spawn_pipe_reader will be lost in the loop and unable to get out without break;

tauri/core/tauri/src/api/process/command.rs

Lines 401 to 425 in 67d7877

	loop {
	buf.clear();
	match tauri_utils::io::read_line(&mut reader, &mut buf) {
	Ok(n) => {
	if n == 0 {
	break;
	}
	let tx_ = tx.clone();
	let line = match character_encoding {
	Some(encoding) => Ok(encoding.decode_with_bom_removal(&buf).0.into()),
	None => String::from_utf8(buf.clone()),
	};
	block_on_task(async move {
	let _ = match line {
	Ok(line) => tx_.send(wrapper(line)).await,
	Err(e) => tx_.send(CommandEvent::Error(e.to_string())).await,
	};
	});
	}
	Err(e) => {
	let tx_ = tx.clone();
	let _ = block_on_task(async move { tx_.send(CommandEvent::Error(e.to_string())).await });
	}
	}
	}

So, the loop in output method will never receive a None value from Reciver.

tauri/core/tauri/src/api/process/command.rs

Lines 362 to 377 in 67d7877

	while let Some(event) = rx.recv().await {
	match event {
	CommandEvent::Terminated(payload) => {
	code = payload.code;
	}
	CommandEvent::Stdout(line) => {
	stdout.push_str(line.as_str());
	stdout.push('\n');
	}
	CommandEvent::Stderr(line) => {
	stderr.push_str(line.as_str());
	stderr.push('\n');
	}
	CommandEvent::Error(_) => {}
	}
	}

[dyxushuai]

Maybe resolves #8572