Open a file with su/sudo inside Emacs

Question

Suppose I want to open a file in an existing Emacs session using su or sudo, without dropping down to a shell and doing sudoedit or

Answer 1

(works only locally. Need to be updated to work correctly via tramp)

A little bit extended Burton's answer:

(defun sudo-find-file (file-name)
"Like find file, but opens the file as root."
(interactive "FSudo Find File: ")
(let ((tramp-file-name (concat "/sudo::" (expand-file-name file-name))))
(find-file tramp-file-name)))


(add-hook 'dired-mode-hook
    (lambda ()
      ;; open current file as sudo 
      (local-set-key (kbd "C-x ") (lambda()
        (interactive)
        (message "!!! SUDO opening %s" (dired-file-name-at-point))
        (sudo-find-file (dired-file-name-at-point))
      ))
    )
)