feat(daemon): follow XDG_RUNTIME_DIR if set (#2171)

If XDG_RUNTIME_DIR is set, put the socket file there.

If not, default to storing it in our data dir. We cannot default to a
path such as /run/user/$UID/ because it does not exist on all systems.
Any system running systemd will set this var by default, and ensure that
the directory it points to is correctly setup.

Author: ellie

crates/atuin-client/src/settings.rs

@@ -667,7 +667,7 @@ impl Settings {
         let data_dir = atuin_common::utils::data_dir();
         let db_path = data_dir.join("history.db");
         let record_store_path = data_dir.join("records.db");
-        let socket_path = data_dir.join("atuin.sock");
+        let socket_path = atuin_common::utils::runtime_dir().join("atuin.sock");
 
         let key_path = data_dir.join("key");
         let session_path = data_dir.join("session");

crates/atuin-common/src/utils.rs

@@ -77,6 +77,10 @@ pub fn data_dir() -> PathBuf {
     data_dir.join("atuin")
 }
 
+pub fn runtime_dir() -> PathBuf {
+    std::env::var("XDG_RUNTIME_DIR").map_or_else(|_| data_dir(), PathBuf::from)
+}
+
 pub fn dotfiles_cache_dir() -> PathBuf {
     // In most cases, this will be  ~/.local/share/atuin/dotfiles/cache
     let data_dir = std::env::var("XDG_DATA_HOME")