Fix restarting issues

* exwm-workspace.el (exwm-workspace--confirm-kill-emacs): Prompt for
unsaved files before restarting; avoid running `server-force-stop'
early; restore the 'client' frame parameter before calling `exwm--exit';
correctly handle emacsclient.

* exwm.el (exwm-restart): Always kill subordinate Emacs instances.

exwm-workspace.el

@@ -25,6 +25,8 @@
 
 ;;; Code:
 
+(require 'server)
+
 (require 'exwm-core)
 
 (defvar exwm-workspace-number 1 "Initial number of workspaces.")
@@ -1046,15 +1048,32 @@ Please check `exwm-workspace--minibuffer-own-frame-p' first."
 
 (defun exwm-workspace--confirm-kill-emacs (prompt &optional force)
   "Confirm before exiting Emacs."
-  (when (or (and force (not (eq force 'no-check)))
-            (and (or (eq force 'no-check) (not exwm--id-buffer-alist))
-                 (y-or-n-p prompt))
-            (yes-or-no-p (format "[EXWM] %d window(s) will be destroyed.  %s"
-                                 (length exwm--id-buffer-alist) prompt)))
-    ;; Run `kill-emacs-hook' before Emacs frames are unmapped so that
-    ;; errors can be visible.
-    (run-hooks 'kill-emacs-hook)
-    (setq kill-emacs-hook nil)
+  (when (cond
+         ((and force (not (eq force 'no-check)))
+          ;; Force killing Emacs.
+          t)
+         ((or (eq force 'no-check) (not exwm--id-buffer-alist))
+          ;; Check if there's any unsaved file.
+          (pcase (catch 'break
+                   (let ((kill-emacs-query-functions
+                          (append kill-emacs-query-functions
+                                  (list (lambda ()
+                                          (throw 'break 'break))))))
+                     (save-buffers-kill-emacs)))
+            (`break (y-or-n-p prompt))
+            (x x)))
+         (t
+          (yes-or-no-p (format "[EXWM] %d window(s) will be destroyed.  %s"
+                               (length exwm--id-buffer-alist) prompt))))
+    ;; Run `kill-emacs-hook' (`server-force-stop' excluded) before Emacs
+    ;; frames are unmapped so that errors (if any) can be visible.
+    (if (memq #'server-force-stop kill-emacs-hook)
+        (progn
+          (setq kill-emacs-hook (delq #'server-force-stop kill-emacs-hook))
+          (run-hooks 'kill-emacs-hook)
+          (setq kill-emacs-hook (list #'server-force-stop)))
+      (run-hooks 'kill-emacs-hook)
+      (setq kill-emacs-hook nil))
     ;; Hide & reparent out all frames (save-set can't be used here since
     ;; X windows will be re-mapped).
     (when (exwm-workspace--minibuffer-own-frame-p)
@@ -1079,22 +1098,20 @@ Please check `exwm-workspace--minibuffer-own-frame-p' first."
                            :parent exwm--root
                            :x 0
                            :y 0))))
-    ;; Exit each module.
-    (exwm--exit)
-    ;; Destroy all resources created by this connection.
-    (xcb:disconnect exwm--connection)
-    (setq exwm--connection nil)
-    ;; Extra cleanups for emacsclient.
+    ;; Restore the 'client' frame parameter (before `exwm--exit').
     (when exwm-workspace--client
       (dolist (f exwm-workspace--list)
         (set-frame-parameter f 'client exwm-workspace--client))
       (when (exwm-workspace--minibuffer-own-frame-p)
         (set-frame-parameter exwm-workspace--minibuffer 'client
-                             exwm-workspace--client))
-      ;; Kill the client.
-      (server-save-buffers-kill-terminal nil))
+                             exwm-workspace--client)))
+    ;; Exit each module.
+    (exwm--exit)
+    ;; Destroy all resources created by this connection.
+    (xcb:disconnect exwm--connection)
+    (setq exwm--connection nil)
     ;; Set the return value.
-    (not exwm-workspace--client)))
+    t))
 
 (defun exwm-workspace--set-desktop-geometry ()
   "Set _NET_DESKTOP_GEOMETRY."

exwm.el

@@ -88,10 +88,29 @@
   "Restart EXWM."
   (interactive)
   (when (exwm-workspace--confirm-kill-emacs "[EXWM] Restart? " 'no-check)
-    (apply #'call-process (car command-line-args) nil nil nil
-           (cdr command-line-args))
-    ;; Kill this instance at last.
-    (kill-emacs)))
+    (let* ((attr (process-attributes (emacs-pid)))
+           (args (cdr (assq 'args attr)))
+           (ppid (cdr (assq 'ppid attr)))
+           (pargs (cdr (assq 'args (process-attributes ppid)))))
+      (cond
+       ((= ppid 1)
+        ;; The parent is the init process.  This probably means this
+        ;; instance is an emacsclient.  Anyway, start a control instance
+        ;; to manage the subsequent ones.
+        (call-process (car command-line-args))
+        (kill-emacs))
+       ((string= args pargs)
+        ;; This is a subordinate instance.  Return a magic number to
+        ;; inform the parent (control instance) to start another one.
+        (kill-emacs ?R))
+       (t
+        ;; This is the control instance.  Keep starting subordinate
+        ;; instances until told to exit.
+        ;; Run `server-force-stop' if it exists.
+        (run-hooks 'kill-emacs-hook)
+        (with-temp-buffer
+          (while (= ?R (shell-command-on-region (point) (point) args))))
+        (kill-emacs))))))
 
 (defun exwm--update-window-type (id &optional force)
   "Update _NET_WM_WINDOW_TYPE."