graceful startup errors instead of panics

- bind socket: eprintln instead of expect (exit 0, not 101)
- write_pid, create_dir_all, set_permissions: check errors
- all errors print to stderr and return cleanly

src/daemon.rs

@@ -38,7 +38,10 @@ pub fn run(config_path: String) {
 
     // Write daemon PID
     let pid_path = state::daemon_pid_path();
-    state::write_pid(&pid_path).ok();
+    if let Err(e) = state::write_pid(&pid_path) {
+        eprintln!("error: write PID at {:?}: {}", pid_path, e);
+        return;
+    }
 
     // Ensure socket path is clean
     let sock_path = state::socket_path();
@@ -46,8 +49,16 @@ pub fn run(config_path: String) {
         let _ = fs::remove_file(&sock_path);
     }
     if let Some(parent) = sock_path.parent() {
-        fs::create_dir_all(parent).ok();
-        let _ = fs::set_permissions(parent, fs::Permissions::from_mode(0o770));
+        if let Err(e) = fs::create_dir_all(parent) {
+            eprintln!("error: create {}: {}", parent.display(), e);
+            let _ = fs::remove_file(&pid_path);
+            return;
+        }
+        if let Err(e) = fs::set_permissions(parent, fs::Permissions::from_mode(0o770)) {
+            eprintln!("error: chmod {}: {}", parent.display(), e);
+            let _ = fs::remove_file(&pid_path);
+            return;
+        }
     }
 
     // Load config
@@ -60,7 +71,14 @@ pub fn run(config_path: String) {
         }
     };
 
-    let listener = UnixListener::bind(&sock_path).expect("bind socket");
+    let listener = match UnixListener::bind(&sock_path) {
+        Ok(l) => l,
+        Err(e) => {
+            eprintln!("error: bind socket at {:?}: {}", sock_path, e);
+            let _ = fs::remove_file(&pid_path);
+            return;
+        }
+    };
     listener.set_nonblocking(true).ok();
 
     let mut procs: HashMap<String, Proc> = HashMap::new();