macos: enable running lan-mouse on macos (#42)

* macos: initial support

- adapted conditional compilation
- moved lan-mouse socket to ~/Library/Caches/lan-mouse-socket.sock instead of XDG_RUNTIME_DIR
- support for mouse input emulation
TODO: Keycode translation, input capture

src/frontend.rs

@@ -126,7 +126,7 @@ pub struct FrontendListener {
 }
 
 impl FrontendListener {
-    #[cfg(unix)]
+    #[cfg(all(unix, not(target_os = "macos")))]
     pub fn socket_path() -> Result<PathBuf> {
         let xdg_runtime_dir = match env::var("XDG_RUNTIME_DIR") {
             Ok(d) => d,
@@ -136,6 +136,20 @@ impl FrontendListener {
         Ok(xdg_runtime_dir.join("lan-mouse-socket.sock"))
     }
 
+    #[cfg(all(unix, target_os = "macos"))]
+    pub fn socket_path() -> Result<PathBuf> {
+        let home = match env::var("HOME") {
+            Ok(d) => d,
+            Err(e) => return Err(anyhow!("could not find HOME: {e}")),
+        };
+        let home = Path::new(home.as_str());
+        let path = home
+            .join("Library")
+            .join("Caches")
+            .join("lan-mouse-socket.sock");
+        Ok(path)
+    }
+
     pub async fn new() -> Option<Result<Self>> {
         #[cfg(unix)]
         let (socket_path, listener) = {