Cannot use serve --open with --port 0

[koalp]

Problem

When using the mdbook serve command with --port 0 and --open options, the opened page is wrong, as the port is 0 instead of the random port attributed by the system.

Steps

1. mdbook init abc --force
2. mdbook serve abc --port 0 --open

Possible Solution(s)

The serving_url should contain the bound port instead of the asked port (0)

mdBook/src/cmd/serve.rs

Line 92 in 3a8faba

let serving_url = format!("http://{address}");

Maybe using something like bind_ephemeral could be used. It would maybe require to move the creation of the warp server in a separate function run before the thread spawn.

mdBook/src/cmd/serve.rs

Lines 88 to 90 in 3a8faba

	let thread_handle = std::thread::spawn(move || {
	serve(build_dir, sockaddr, reload_tx, &file_404);
	});

Notes

No response

Version

mdbook v0.4.47

[szabgab]

I can confirm the problem on Linux and sending a PR fixing it.