(defvar emacs-lock-from-exiting nil
"Whether Emacs is locked to prevent exiting. See `check-emacs-lock'.")
(defvar emacs-lock-buffer-locked nil
"Whether a shell or telnet buffer was locked when its process was killed.")
(put 'emacs-lock-buffer-locked 'permanent-local t)
(defun check-emacs-lock ()
"Check if variable `emacs-lock-from-exiting' is t for any buffer.
If any locked buffer is found, signal error and display the buffer's name."
(dolist (buffer (buffer-list))
(error "Emacs is locked from exit due to buffer: %s" (buffer-name))))))
(defun toggle-emacs-lock ()
"Toggle `emacs-lock-from-exiting' for the current buffer.
(setq emacs-lock-from-exiting (not emacs-lock-from-exiting))
(message "Buffer is now locked")
(message "Buffer is now unlocked")))
(defun emacs-lock-check-buffer-lock ()
"Check if variable `emacs-lock-from-exiting' is t for a buffer.
If the buffer is locked, signal error and display its name."
(error "Buffer `%s' is locked, can't delete it" (buffer-name))))
(defun emacs-lock-shell-sentinel ()
(get-buffer-process (buffer-name)) (function emacs-lock-clear-sentinel)))
(defun emacs-lock-clear-sentinel (proc str)
(setq emacs-lock-from-exiting nil)
(setq emacs-lock-buffer-locked t)
(message "Buffer is now unlocked"))
(setq emacs-lock-buffer-locked nil)))
(defun emacs-lock-was-buffer-locked ()
(setq emacs-lock-from-exiting t)))
(add-hook 'kill-emacs-hook 'check-emacs-lock)
(add-hook 'kill-buffer-hook 'emacs-lock-check-buffer-lock)
(add-hook 'shell-mode-hook 'emacs-lock-was-buffer-locked)
(add-hook 'shell-mode-hook 'emacs-lock-shell-sentinel)
(add-hook 'telnet-mode-hook 'emacs-lock-was-buffer-locked)
(add-hook 'telnet-mode-hook 'emacs-lock-shell-sentinel)