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[gnu-emacs] / lisp / server.el

;;; server.el --- Lisp code for GNU Emacs running as server process.

;; Copyright (C) 1986, 1987, 1992, 1994, 1995 Free Software Foundation, Inc.

;; Author: William Sommerfeld <wesommer@athena.mit.edu>
;; Keywords: processes

;; Changes by peck@sun.com and by rms.

;; This file is part of GNU Emacs.

;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary:

;; This Lisp code is run in Emacs when it is to operate as
;; a server for other processes.

;; Load this library and do M-x server-edit to enable Emacs as a server.
;; Emacs runs the program ../arch-lib/emacsserver as a subprocess
;; for communication with clients.  If there are no client buffers to edit, 
;; server-edit acts like (switch-to-buffer (other-buffer))

;; When some other program runs "the editor" to edit a file,
;; "the editor" can be the Emacs client program ../lib-src/emacsclient.
;; This program transmits the file names to Emacs through
;; the server subprocess, and Emacs visits them and lets you edit them.

;; Note that any number of clients may dispatch files to emacs to be edited.

;; When you finish editing a Server buffer, again call server-edit
;; to mark that buffer as done for the client and switch to the next 
;; Server buffer.  When all the buffers for a client have been edited 
;; and exited with server-edit, the client "editor" will return
;; to the program that invoked it.  

;; Your editing commands and Emacs's display output go to and from
;; the terminal in the usual way.  Thus, server operation is possible
;; only when Emacs can talk to the terminal at the time you invoke
;; the client.  This is possible in four cases:

;; 1. On a window system, where Emacs runs in one window and the
;; program that wants to use "the editor" runs in another.

;; 2. On a multi-terminal system, where Emacs runs on one terminal and the
;; program that wants to use "the editor" runs on another.

;; 3. When the program that wants to use "the editor" is running
;; as a subprocess of Emacs.

;; 4. On a system with job control, when Emacs is suspended, the program
;; that wants to use "the editor" will stop and display
;; "Waiting for Emacs...".  It can then be suspended, and Emacs can be
;; brought into the foreground for editing.  When done editing, Emacs is
;; suspended again, and the client program is brought into the foreground.

;; The buffer local variable "server-buffer-clients" lists 
;; the clients who are waiting for this buffer to be edited.  
;; The global variable "server-clients" lists all the waiting clients,
;; and which files are yet to be edited for each.

;;; Code:
\f
(defvar server-program (expand-file-name "emacsserver" exec-directory)
  "*The program to use as the edit server.")

(defvar server-visit-hook nil
  "*List of hooks to call when visiting a file for the Emacs server.")

(defvar server-switch-hook nil
  "*List of hooks to call when switching to a buffer for the Emacs server.")

(defvar server-done-hook nil
  "*List of hooks to call when done editing a buffer for the Emacs server.")

(defvar server-process nil 
  "the current server process")

(defvar server-previous-string "")

(defvar server-clients nil
  "List of current server clients.
Each element is (CLIENTID BUFFERS...) where CLIENTID is a string
that can be given to the server process to identify a client.
When a buffer is marked as \"done\", it is removed from this list.")

(defvar server-buffer-clients nil
  "List of clientids for clients requesting editing of current buffer.")
(make-variable-buffer-local 'server-buffer-clients)
;; Changing major modes should not erase this local.
(put 'server-buffer-clients 'permanent-local t)

(defvar server-window nil
  "*The window to use for selecting Emacs server buffers.
If nil, use the selected window.
If it is a frame, use the frame's selected window.")

(defvar server-temp-file-regexp "^/tmp/Re\\|/draft$"
  "*Regexp which should match filenames of temporary files
which are deleted and reused after each edit
by the programs that invoke the emacs server.")

(or (assq 'server-buffer-clients minor-mode-alist)
    (setq minor-mode-alist (cons '(server-buffer-clients " Server") minor-mode-alist)))

;; If a *server* buffer exists,
;; write STRING to it for logging purposes.
(defun server-log (string)
  (if (get-buffer "*server*")
      (save-excursion
        (set-buffer "*server*")
        (goto-char (point-max))
        (insert (current-time-string) " " string)
        (or (bolp) (newline)))))

(defun server-sentinel (proc msg)
  (cond ((eq (process-status proc) 'exit)
         (server-log (message "Server subprocess exited")))
        ((eq (process-status proc) 'signal)
         (server-log (message "Server subprocess killed")))))

;;;###autoload
(defun server-start (&optional leave-dead)
  "Allow this Emacs process to be a server for client processes.
This starts a server communications subprocess through which
client \"editors\" can send your editing commands to this Emacs job.
To use the server, set up the program `emacsclient' in the
Emacs distribution as your standard \"editor\".

Prefix arg means just kill any existing server communications subprocess."
  (interactive "P")
  ;; kill it dead!
  (if server-process
      (progn
        (set-process-sentinel server-process nil)
        (condition-case () (delete-process server-process) (error nil))))
  (condition-case () (delete-file "~/.emacs_server") (error nil))
  (let* ((sysname (system-name))
         (dot-index (string-match "\\." sysname)))
    (condition-case ()
        (delete-file (format "/tmp/esrv%d-%s" (user-uid) sysname))
      (error nil))
    ;; In case the server file name was made with a domainless hostname,
    ;; try deleting that name too.
    (if dot-index
        (condition-case ()
            (delete-file (format "/tmp/esrv%d-%s" (user-uid)
                                 (substring sysname 0 dot-index)))
          (error nil))))
  ;; If we already had a server, clear out associated status.
  (while server-clients
    (let ((buffer (nth 1 (car server-clients))))
      (server-buffer-done buffer)))
  (if leave-dead
      nil
    (if server-process
        (server-log (message "Restarting server")))
    ;; Using a pty is wasteful, and the separate session causes
    ;; annoyance sometimes (some systems kill idle sessions).
    (let ((process-connection-type nil))
      (setq server-process (start-process "server" nil server-program)))
    (set-process-sentinel server-process 'server-sentinel)
    (set-process-filter server-process 'server-process-filter)
    (process-kill-without-query server-process)))
\f
;Process a request from the server to edit some files.
;Format of STRING is "Client: CLIENTID PATH PATH PATH... \n"
(defun server-process-filter (proc string)
  (server-log string)
  (setq string (concat server-previous-string string))
  ;; If the input is multiple lines,
  ;; process each line individually.
  (while (string-match "\n" string)
    (let ((request (substring string 0 (match-beginning 0)))
          client nowait
          (files nil)
          (lineno 1))
      ;; Remove this line from STRING.
      (setq string (substring string (match-end 0)))      
      (if (string-match "^Error: " request)
          (message "Server error: %s" (substring request (match-end 0)))
        (if (string-match "^Client: " request)
            (progn
              (setq request (substring request (match-end 0)))
              (setq client (list (substring request 0 (string-match " " request))))
              (setq request (substring request (match-end 0)))
              (setq foofoo request)
              (while (string-match "[^ ]+ " request)
                (let ((arg
                       (substring request (match-beginning 0) (1- (match-end 0)))))
                  (setq request (substring request (match-end 0)))
                  (if (string-match "\\`-nowait" arg)
                      (setq nowait t)
                    (if (string-match "\\`\\+[0-9]+\\'" arg)
                        ;; ARG is a line number option.
                        (setq lineno (read (substring arg 1)))
                      ;; ARG is a file name.
                      ;; Collapse multiple slashes to single slashes.
                      (setq arg (command-line-normalize-file-name arg))
                      (setq files
                            (cons (list arg lineno)
                                  files))
                      (setq lineno 1)))))
              (server-visit-files files client nowait)
              ;; CLIENT is now a list (CLIENTNUM BUFFERS...)
              (or nowait
                  (setq server-clients (cons client server-clients)))
              (server-switch-buffer (nth 1 client))
              (run-hooks 'server-switch-hook)
              (message (substitute-command-keys
                        "When done with a buffer, type \\[server-edit]")))))))
  ;; Save for later any partial line that remains.
  (setq server-previous-string string))

(defun server-visit-files (files client &optional nowait)
  "Finds FILES and returns the list CLIENT with the buffers nconc'd.
FILES is an alist whose elements are (FILENAME LINENUMBER).
NOWAIT non-nil means this client is not waiting for the results,
so don't mark these buffers specially, just visit them normally."
  ;; Bind last-nonmenu-event to force use of keyboard, not mouse, for queries.
  (let (client-record (last-nonmenu-event t) (obuf (current-buffer)))
    ;; Restore the current buffer afterward, but not using save-excursion,
    ;; because we don't want to save point in this buffer
    ;; if it happens to be one of those specified by the server.
    (unwind-protect
        (while files
          ;; If there is an existing buffer modified or the file is modified,
          ;; revert it.
          ;; If there is an existing buffer with deleted file, offer to write it.
          (let* ((filen (car (car files)))
                 (obuf (get-file-buffer filen)))
            (if (and obuf (set-buffer obuf))
                (if (file-exists-p filen)
                    (if (or (not (verify-visited-file-modtime obuf))
                            (buffer-modified-p obuf))
                        (revert-buffer t nil))
                  (if (y-or-n-p
                       (concat "File no longer exists: "
                               filen
                               ", write buffer to file? "))
                      (write-file filen)))
              (set-buffer (find-file-noselect filen))
              (run-hooks 'server-visit-hook)))
          (goto-line (nth 1 (car files)))
          (if (not nowait)
              (setq server-buffer-clients
                    (cons (car client) server-buffer-clients)))
          (setq client-record (cons (current-buffer) client-record))
          (setq files (cdr files)))
      (set-buffer obuf))
    (nconc client client-record)))
\f
(defun server-buffer-done (buffer)
  "Mark BUFFER as \"done\" for its client(s).
This buries the buffer, then returns a list of the form (NEXT-BUFFER KILLED).
NEXT-BUFFER is another server buffer, as a suggestion for what to select next,
or nil.  KILLED is t if we killed BUFFER (because it was a temp file)."
  (let ((running (eq (process-status server-process) 'run))
        (next-buffer nil)
        (killed nil)
        (first t)
        (old-clients server-clients))
    (while old-clients
      (let ((client (car old-clients)))
        (or next-buffer 
            (setq next-buffer (nth 1 (memq buffer client))))
        (delq buffer client)
        ;; Delete all dead buffers from CLIENT.
        (let ((tail client))
          (while tail
            (and (bufferp (car tail))
                 (null (buffer-name (car tail)))
                 (delq (car tail) client))
            (setq tail (cdr tail))))
        ;; If client now has no pending buffers,
        ;; tell it that it is done, and forget it entirely.
        (if (cdr client) nil
          (if running
              (progn
                ;; Don't send emacsserver two commands in close succession.
                ;; It cannot handle that.
                (or first (sit-for 1))
                (setq first nil)
                (send-string server-process 
                             (format "Close: %s Done\n" (car client)))
                (server-log (format "Close: %s Done\n" (car client)))))
          (setq server-clients (delq client server-clients))))
      (setq old-clients (cdr old-clients)))
    (if (and (bufferp buffer) (buffer-name buffer))
        (progn
          (save-excursion
            (set-buffer buffer)
            (setq server-buffer-clients nil)
            (run-hooks 'server-done-hook))
          (if (server-temp-file-p buffer)
              (progn (kill-buffer buffer)
                     (setq killed t))
            (bury-buffer buffer))))
    (list next-buffer killed)))

(defun server-temp-file-p (buffer)
  "Return non-nil if BUFFER contains a file considered temporary.
These are files whose names suggest they are repeatedly
reused to pass information to another program.

The variable `server-temp-file-regexp' controls which filenames
are considered temporary."
  (and (buffer-file-name buffer)
       (string-match server-temp-file-regexp (buffer-file-name buffer))))

(defun server-done ()
  "Offer to save current buffer, mark it as \"done\" for clients.
This buries the buffer, then returns a list of the form (NEXT-BUFFER KILLED).
NEXT-BUFFER is another server buffer, as a suggestion for what to select next,
or nil.  KILLED is t if we killed the BUFFER (because it was a temp file)."
  (let ((buffer (current-buffer)))
    (if server-buffer-clients
        (progn
          (if (server-temp-file-p buffer)
              ;; For a temp file, save, and do make a non-numeric backup
              ;; (unless make-backup-files is nil).
              (let ((version-control nil)
                    (buffer-backed-up nil))
                (save-buffer))
            (if (and (buffer-modified-p)
                     (y-or-n-p (concat "Save file " buffer-file-name "? ")))
                (save-buffer buffer)))
          (server-buffer-done buffer)))))

;; Ask before killing a server buffer.
;; It was suggested to release its client instead,
;; but I think that is dangerous--the client would proceed
;; using whatever is on disk in that file. -- rms.
(defun server-kill-buffer-query-function ()
  (or (not server-buffer-clients)
      (yes-or-no-p (format "Buffer `%s' still has clients; kill it? "
                           (buffer-name (current-buffer))))))

(add-hook 'kill-buffer-query-functions
          'server-kill-buffer-query-function)

(defun server-kill-emacs-query-function ()
  (let (live-client
        (tail server-clients))
    ;; See if any clients have any buffers that are still alive.
    (while tail
      (if (memq t (mapcar 'stringp (mapcar 'buffer-name (cdr (car tail)))))
          (setq live-client t))
      (setq tail (cdr tail)))
    (or (not live-client)
        (yes-or-no-p "Server buffers still have clients; exit anyway? "))))

(add-hook 'kill-emacs-query-functions 'server-kill-emacs-query-function)
\f
(defun server-edit (&optional arg)
  "Switch to next server editing buffer; say \"Done\" for current buffer.
If a server buffer is current, it is marked \"done\" and optionally saved.
When all of a client's buffers are marked as \"done\", the client is notified.

Temporary files such as MH <draft> files are always saved and backed up,
no questions asked.  (The variable `make-backup-files', if nil, still
inhibits a backup; you can set it locally in a particular buffer to
prevent a backup for it.)  The variable `server-temp-file-regexp' controls
which filenames are considered temporary.

If invoked with a prefix argument, or if there is no server process running, 
starts server process and that is all.  Invoked by \\[server-edit]."
  (interactive "P")
  (if (or arg
          (not server-process)
          (memq (process-status server-process) '(signal exit)))
      (server-start nil)
    (apply 'server-switch-buffer (server-done))))

(defun server-switch-buffer (&optional next-buffer killed-one)
  "Switch to another buffer, preferably one that has a client.
Arg NEXT-BUFFER is a suggestion; if it is a live buffer, use it."
  ;; KILLED-ONE is t in a recursive call
  ;; if we have already killed one temp-file server buffer.
  ;; This means we should avoid the final "switch to some other buffer"
  ;; since we've already effectively done that.
  (cond ((and (windowp server-window)
              (window-live-p server-window))
         (select-window server-window))
        ((framep server-window)
         (if (not (frame-live-p server-window))
             (setq server-window (make-frame)))
         (select-window (frame-selected-window server-window))))
  (if (window-minibuffer-p (selected-window))
      (select-window (next-window nil 'nomini 0)))
  ;; Move to a non-dedicated window, if we have one.
  (let ((last-window (previous-window nil 'nomini 0)))
    (while (and (window-dedicated-p (selected-window))
                (not (eq last-window (selected-window))))
      (select-window (next-window nil 'nomini 0))))
  (set-window-dedicated-p (selected-window) nil)
  (if next-buffer
      (if (and (bufferp next-buffer)
               (buffer-name next-buffer))
          (switch-to-buffer next-buffer)
        ;; If NEXT-BUFFER is a dead buffer,
        ;; remove the server records for it
        ;; and try the next surviving server buffer.
        (apply 'server-switch-buffer
               (server-buffer-done next-buffer)))
    (if server-clients
        (server-switch-buffer (nth 1 (car server-clients)) killed-one)
      (if (not killed-one)
          (switch-to-buffer (other-buffer))))))

(global-set-key "\C-x#" 'server-edit)
\f
(provide 'server)

;;; server.el ends here