Handle previous sockets in Listener::new()

apps/magpie/src/service/ipc.rs

@@ -17,6 +17,8 @@ use slab::Slab;
 use crate::protocol::*;
 use crate::service::window::{WindowMessage, WindowMessageSender};
 
+use std::io::{Error, ErrorKind};
+
 const SOCK_NAME: &str = "magpie.sock";
 
 #[derive(Debug)]
@@ -71,8 +73,24 @@ impl Listener {
         let sock_dir = std::env::var("XDG_RUNTIME_DIR").expect("XDG_RUNTIME_DIR not set");
         let sock_dir = Path::new(&sock_dir);
         let sock_path = sock_dir.join(SOCK_NAME);
-        eprintln!("Making socket at: {:?}", sock_path);
 
+        match UnixStream::connect(&sock_path) {
+            Ok(_) => {
+                eprintln!("Socket is already in use. Another instance of Magpie may be running.");
+                let kind = ErrorKind::AddrInUse;
+                let error = Error::new(kind, "Socket is already in use.");
+                return Err(error);
+            }
+            Err(ref err) if err.kind() == ErrorKind::ConnectionRefused => {
+                eprintln!("Found leftover socket; removing");
+                std::fs::remove_file(&sock_path)?;
+            }
+            Err(ref err) if err.kind() == ErrorKind::NotFound => {}
+            Err(err) => return Err(err)
+
+        }
+
+        eprintln!("Making socket at: {:?}", sock_path);
         let uds = UnixListener::bind(&sock_path)?;
         let path = sock_path.to_path_buf();
         Ok(Self{uds, path})