From 779ce5b2e1133b7b43dd1221ad65d4d2534ad860 Mon Sep 17 00:00:00 2001
From: Gabor Szabo <gabor@szabgab.com>
Date: Wed, 2 Apr 2025 11:26:46 +0300
Subject: [PATCH] When running serve check if port is available

Give a nice explanation if it is used or if it is a protected port.
Closes #2631
---
 src/cmd/serve.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/cmd/serve.rs b/src/cmd/serve.rs
index 7b1ccab6eb..cd371a682f 100644
--- a/src/cmd/serve.rs
+++ b/src/cmd/serve.rs
@@ -69,6 +69,12 @@ pub fn execute(args: &ArgMatches) -> Result<()> {
     update_config(&mut book);
     book.build()?;
 
+    let listener = std::net::TcpListener::bind(&address);
+    if listener.is_err() {
+        return Err(anyhow::anyhow!("Unable to bind to address: {} (It is either a protected port or it is used already. Try to another port or use --port 0 to select a random port. ", address).into());
+    }
+    drop(listener);
+
     let sockaddr: SocketAddr = address
         .to_socket_addrs()?
         .next()