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;;; server.el --- Lisp code for GNU Emacs running as server process
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;; Copyright (C) 1986, 1987, 1992, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
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;;   2001, 2002, 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
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;; Author: William Sommerfeld <wesommer@athena.mit.edu>
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;; Maintainer: FSF
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;; Keywords: processes
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;; Changes by peck@sun.com and by rms.
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;; Overhaul by Karoly Lorentey <lorentey@elte.hu> for multi-tty support.
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;; 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
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;; the Free Software Foundation; either version 3, or (at your option)
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;; 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
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;; along with GNU Emacs; see the file COPYING.  If not, write to the
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;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.
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;;; Commentary:
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;; This Lisp code is run in Emacs when it is to operate as
;; a server for other processes.
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;; Load this library and do M-x server-edit to enable Emacs as a server.
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;; Emacs opens up a socket for communication with clients.  If there are no
;; client buffers to edit, server-edit acts like (switch-to-buffer
;; (other-buffer))
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;; 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.
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;; Note that any number of clients may dispatch files to Emacs to be edited.
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;; When you finish editing a Server buffer, again call server-edit
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;; 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
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;; and exited with server-edit, the client "editor" will return
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;; to the program that invoked it.
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;; 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:
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;; 1. On a window system, where Emacs runs in one window and the
;; program that wants to use "the editor" runs in another.
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;; 2. On a multi-terminal system, where Emacs runs on one terminal and the
;; program that wants to use "the editor" runs on another.
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;; 3. When the program that wants to use "the editor" is running
;; as a subprocess of Emacs.
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;; 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.
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;; The buffer local variable "server-buffer-clients" lists
;; the clients who are waiting for this buffer to be edited.
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;; The global variable "server-clients" lists all the waiting clients,
;; and which files are yet to be edited for each.
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;;; Code:
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(eval-when-compile (require 'cl))

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(defgroup server nil
  "Emacs running as a server process."
  :group 'external)

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(defcustom server-use-tcp nil
  "If non-nil, use TCP sockets instead of local sockets."
  :set #'(lambda (sym val)
           (unless (featurep 'make-network-process '(:family local))
             (setq val t)
             (unless load-in-progress
               (message "Local sockets unsupported, using TCP sockets")))
           (when val (random t))
           (set-default sym val))
  :group 'server
  :type 'boolean
  :version "22.1")

(defcustom server-host nil
  "The name or IP address to use as host address of the server process.
If set, the server accepts remote connections; otherwise it is local."
  :group 'server
  :type '(choice
          (string :tag "Name or IP address")
          (const :tag "Local" nil))
  :version "22.1")
(put 'server-host 'risky-local-variable t)

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(defcustom server-auth-dir (concat user-emacs-directory "server/")
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  "Directory for server authentication files."
  :group 'server
  :type 'directory
  :version "22.1")
(put 'server-auth-dir 'risky-local-variable t)

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(defcustom server-raise-frame t
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  "If non-nil, raise frame when switching to a buffer."
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  :group 'server
  :type 'boolean
  :version "22.1")

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(defcustom server-visit-hook nil
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  "Hook run when visiting a file for the Emacs server."
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  :group 'server
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  :type 'hook)
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(defcustom server-switch-hook nil
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  "Hook run when switching to a buffer for the Emacs server."
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  :group 'server
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  :type 'hook)
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(defcustom server-done-hook nil
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  "Hook run when done editing a buffer for the Emacs server."
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  :group 'server
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  :type 'hook)
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(defvar server-process nil
  "The current server process.")
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(defvar server-clients nil
  "List of current server clients.
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Each element is (PROC PROPERTIES...) where PROC is a process object,
and PROPERTIES is an association list of client properties.")
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(defvar server-buffer-clients nil
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  "List of client processes requesting editing of current buffer.")
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(make-variable-buffer-local 'server-buffer-clients)
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;; Changing major modes should not erase this local.
(put 'server-buffer-clients 'permanent-local t)

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(defcustom server-window nil
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  "Specification of the window to use for selecting Emacs server buffers.
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If nil, use the selected window.
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If it is a function, it should take one argument (a buffer) and
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display and select it.  A common value is `pop-to-buffer'.
If it is a window, use that.
If it is a frame, use the frame's selected window.

It is not meaningful to set this to a specific frame or window with Custom.
Only programs can do so."
  :group 'server
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  :version "22.1"
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  :type '(choice (const :tag "Use selected window"
			:match (lambda (widget value)
				 (not (functionp value)))
			nil)
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		 (function-item :tag "Display in new frame" switch-to-buffer-other-frame)
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		 (function-item :tag "Use pop-to-buffer" pop-to-buffer)
		 (function :tag "Other function")))
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(defcustom server-temp-file-regexp "^/tmp/Re\\|/draft$"
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  "Regexp matching names of temporary files.
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These are deleted and reused after each edit by the programs that
invoke the Emacs server."
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  :group 'server
  :type 'regexp)
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(defcustom server-kill-new-buffers t
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  "Whether to kill buffers when done with them.
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If non-nil, kill a buffer unless it already existed before editing
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it with Emacs server.  If nil, kill only buffers as specified by
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`server-temp-file-regexp'.
Please note that only buffers are killed that still have a client,
i.e. buffers visited which \"emacsclient --no-wait\" are never killed in
this way."
  :group 'server
  :type 'boolean
  :version "21.1")

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(or (assq 'server-buffer-clients minor-mode-alist)
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    (push '(server-buffer-clients " Server") minor-mode-alist))
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(defvar server-existing-buffer nil
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  "Non-nil means the buffer existed before the server was asked to visit it.
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This means that the server should not kill the buffer when you say you
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are done with it in the server.")
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(make-variable-buffer-local 'server-existing-buffer)

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(defvar server-name "server")

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(defvar server-socket-dir nil
  "The directory in which to place the server socket.
Initialized by `server-start'.")
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(defun server-client (proc)
  "Return the Emacs client corresponding to PROC.
PROC must be a process object.
The car of the result is PROC; the cdr is an association list.
See `server-client-get' and `server-client-set'."
  (assq proc server-clients))

(defun server-client-get (client property)
  "Get the value of PROPERTY in CLIENT.
CLIENT may be a process object, or a client returned by `server-client'.
Return nil if CLIENT has no such property."
  (or (listp client) (setq client (server-client client)))
  (cdr (assq property (cdr client))))

(defun server-client-set (client property value)
  "Set the PROPERTY to VALUE in CLIENT, and return VALUE.
CLIENT may be a process object, or a client returned by `server-client'."
  (let (p proc)
    (if (listp client)
	(setq proc (car client))
      (setq proc client
	    client (server-client client)))
    (setq p (assq property client))
    (cond
     (p (setcdr p value))
     (client (setcdr client (cons (cons property value) (cdr client))))
     (t (setq server-clients
	      `((,proc (,property . ,value)) . ,server-clients))))
    value))

(defun server-clients-with (property value)
  "Return a list of clients with PROPERTY set to VALUE."
  (let (result)
    (dolist (client server-clients result)
      (when (equal value (server-client-get client property))
	(setq result (cons (car client) result))))))

(defun server-add-client (proc)
  "Create a client for process PROC, if it doesn't already have one.
New clients have no properties."
  (unless (server-client proc)
    (setq server-clients (cons (cons proc nil)
			       server-clients))))

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(defun server-getenv-from (env variable)
  "Get the value of VARIABLE in ENV.
VARIABLE should be a string.  Value is nil if VARIABLE is
undefined in ENV.  Otherwise, value is a string.

ENV should be in the same format as `process-environment'."
  (let (entry result)
    (while (and env (null result))
      (setq entry (car env)
	    env (cdr env))
      (if (and (> (length entry) (length variable))
	       (eq ?= (aref entry (length variable)))
	       (equal variable (substring entry 0 (length variable))))
	  (setq result (substring entry (+ (length variable) 1)))))
    result))

(defmacro server-with-environment (env vars &rest body)
  "Evaluate BODY with environment variables VARS set to those in ENV.
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The environment variables are then restored to their previous values.

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VARS should be a list of strings.
ENV should be in the same format as `process-environment'."
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  (declare (indent 2))
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  (let ((old-env (make-symbol "old-env"))
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	(var (make-symbol "var"))
	(value (make-symbol "value"))
	(pair (make-symbol "pair")))
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    `(let ((,old-env process-environment))
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       (dolist (,var ,vars)
	 (let ((,value (server-getenv-from ,env ,var)))
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	   (setq process-environment
		 (cons (if (null ,value)
			   ,var
			 (concat ,var "=" ,value))
		       process-environment))))
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       (unwind-protect
	   (progn ,@body)
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	 (setq process-environment ,old-env)))))
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(defun server-delete-client (client &optional noframe)
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  "Delete CLIENT, including its buffers, terminals and frames.
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If NOFRAME is non-nil, let the frames live.  (To be used from
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`delete-frame-functions'.)"
  (server-log (concat "server-delete-client" (if noframe " noframe"))
	      client)
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  ;; Force a new lookup of client (prevents infinite recursion).
  (setq client (server-client
		(if (listp client) (car client) client)))
  (let ((proc (car client))
	(buffers (server-client-get client 'buffers)))
    (when client

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      ;; Kill the client's buffers.
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      (dolist (buf buffers)
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	(when (buffer-live-p buf)
	  (with-current-buffer buf
	    ;; Kill the buffer if necessary.
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	    (when (and (equal server-buffer-clients
			      (list proc))
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		       (or (and server-kill-new-buffers
				(not server-existing-buffer))
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			   (server-temp-file-p))
		       (not (buffer-modified-p)))
	      (let (flag)
		(unwind-protect
		    (progn (setq server-buffer-clients nil)
			   (kill-buffer (current-buffer))
			   (setq flag t))
		  (unless flag
		    ;; Restore clients if user pressed C-g in `kill-buffer'.
		    (setq server-buffer-clients (list proc)))))))))
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      ;; Delete the client's frames.
      (unless noframe
	(dolist (frame (frame-list))
	  (when (and (frame-live-p frame)
		     (equal proc (frame-parameter frame 'client)))
	    ;; Prevent `server-handle-delete-frame' from calling us
	    ;; recursively.
	    (set-frame-parameter frame 'client nil)
	    (delete-frame frame))))

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      (setq server-clients (delq client server-clients))

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      ;; Delete the client's tty.
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      (let ((terminal (server-client-get client 'terminal)))
	(when (eq (terminal-live-p terminal) t)
	  (delete-terminal terminal)))
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      ;; Delete the client's process.
      (if (eq (process-status (car client)) 'open)
	  (delete-process (car client)))

      (server-log "Deleted" proc))))

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(defun server-log (string &optional client)
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  "If a *server* buffer exists, write STRING to it for logging purposes.
If CLIENT is non-nil, add a description of it to the logged
message."
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  (when (get-buffer "*server*")
    (with-current-buffer "*server*"
      (goto-char (point-max))
      (insert (current-time-string)
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	      (cond
	       ((null client) " ")
	       ((listp client) (format " %s: " (car client)))
	       (t (format " %s: " client)))
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	      string)
      (or (bolp) (newline)))))
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(defun server-sentinel (proc msg)
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  "The process sentinel for Emacs server connections."
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  ;; If this is a new client process, set the query-on-exit flag to nil
  ;; for this process (it isn't inherited from the server process).
  (when (and (eq (process-status proc) 'open)
	     (process-query-on-exit-flag proc))
    (set-process-query-on-exit-flag proc nil))
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  ;; Delete the associated connection file, if applicable.
  ;; This is actually problematic: the file may have been overwritten by
  ;; another Emacs server in the mean time, so it's not ours any more.
  ;; (and (process-contact proc :server)
  ;;      (eq (process-status proc) 'closed)
  ;;      (ignore-errors (delete-file (process-get proc :server-file))))
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  (server-log (format "Status changed to %s: %s" (process-status proc) msg) proc)
  (server-delete-client proc))
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(defun server-handle-delete-frame (frame)
  "Delete the client connection when the emacsclient frame is deleted."
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  (let ((proc (frame-parameter frame 'client)))
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    (when (and (frame-live-p frame)
	       proc
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	       ;; See if this is the last frame for this client.
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	       (>= 1 (let ((frame-num 0))
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		      (dolist (f (frame-list))
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			(when (eq proc (frame-parameter f 'client))
			  (setq frame-num (1+ frame-num))))
		      frame-num)))
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      (server-log (format "server-handle-delete-frame, frame %s" frame) proc)
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      (server-delete-client proc 'noframe)))) ; Let delete-frame delete the frame later.
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(defun server-handle-suspend-tty (terminal)
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  "Notify the emacsclient process to suspend itself when its tty device is suspended."
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  (dolist (proc (server-clients-with 'terminal terminal))
    (server-log (format "server-handle-suspend-tty, terminal %s" terminal) proc)
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    (condition-case err
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	(server-send-string proc "-suspend \n")
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      (file-error (condition-case nil (server-delete-client proc) (error nil))))))
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(defun server-unquote-arg (arg)
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  "Remove &-quotation from ARG.
See `server-quote-arg' and `server-process-filter'."
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  (replace-regexp-in-string
   "&." (lambda (s)
	  (case (aref s 1)
	    (?& "&")
	    (?- "-")
	    (?n "\n")
	    (t " ")))
   arg t t))
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(defun server-quote-arg (arg)
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  "In ARG, insert a & before each &, each space, each newline, and -.
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Change spaces to underscores, too, so that the return value never
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contains a space.

See `server-unquote-arg' and `server-process-filter'."
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  (replace-regexp-in-string
   "[-&\n ]" (lambda (s)
	       (case (aref s 0)
		 (?& "&&")
		 (?- "&-")
		 (?\n "&n")
		 (?\s "&_")))
   arg t t))

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(defun server-send-string (proc string)
  "A wrapper around `proc-send-string' for logging."
  (server-log (concat "Sent " string) proc)
  (process-send-string proc string))

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(defun server-ensure-safe-dir (dir)
  "Make sure DIR is a directory with no race-condition issues.
Creates the directory if necessary and makes sure:
- there's no symlink involved
- it's owned by us
- it's not readable/writable by anybody else."
  (setq dir (directory-file-name dir))
  (let ((attrs (file-attributes dir)))
    (unless attrs
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      (letf (((default-file-modes) ?\700)) (make-directory dir t))
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      (setq attrs (file-attributes dir)))
    ;; Check that it's safe for use.
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    (unless (and (eq t (car attrs)) (eql (nth 2 attrs) (user-uid))
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                 (or (eq system-type 'windows-nt)
                     (zerop (logand ?\077 (file-modes dir)))))
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      (error "The directory %s is unsafe" dir))))

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;;;###autoload
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(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
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client \"editors\" can send your editing commands to this Emacs
job.  To use the server, set up the program `emacsclient' in the
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Emacs distribution as your standard \"editor\".

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Optional argument LEAVE-DEAD (interactively, a prefix arg) means just
kill any existing server communications subprocess."
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  (interactive "P")
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  (when (or
	 (not server-clients)
	 (yes-or-no-p
	  "The current server still has clients; delete them? "))
    ;; It is safe to get the user id now.
    (setq server-socket-dir (or server-socket-dir
				(format "/tmp/emacs%d" (user-uid))))
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    (when server-process
      ;; kill it dead!
      (ignore-errors (delete-process server-process)))
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    ;; Delete the socket files made by previous server invocations.
    (condition-case ()
	(delete-file (expand-file-name server-name server-socket-dir))
      (error nil))
    ;; If this Emacs already had a server, clear out associated status.
    (while server-clients
      (server-delete-client (car server-clients)))
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    ;; Now any previous server is properly stopped.
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    (if leave-dead
	(progn
	  (server-log (message "Server stopped"))
	  (setq server-process nil))
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      (let* ((server-dir (if server-use-tcp server-auth-dir server-socket-dir))
	     (server-file (expand-file-name server-name server-dir)))
	;; Make sure there is a safe directory in which to place the socket.
	(server-ensure-safe-dir server-dir)
	;; Remove any leftover socket or authentication file.
	(ignore-errors (delete-file server-file))
	(when server-process
	  (server-log (message "Restarting server")))
	(letf (((default-file-modes) ?\700))
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	  (add-hook 'suspend-tty-functions 'server-handle-suspend-tty)
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	  (add-hook 'delete-frame-functions 'server-handle-delete-frame)
	  (add-hook 'kill-buffer-query-functions 'server-kill-buffer-query-function)
	  (add-hook 'kill-emacs-query-functions 'server-kill-emacs-query-function)
	  (setq server-process
		(apply #'make-network-process
		       :name server-name
		       :server t
		       :noquery t
		       :sentinel 'server-sentinel
		       :filter 'server-process-filter
		       ;; We must receive file names without being decoded.
		       ;; Those are decoded by server-process-filter according
		       ;; to file-name-coding-system.
		       :coding 'raw-text
		       ;; The rest of the args depends on the kind of socket used.
		       (if server-use-tcp
			   (list :family nil
				 :service t
				 :host (or server-host 'local)
				 :plist '(:authenticated nil))
			 (list :family 'local
			       :service server-file
			       :plist '(:authenticated t)))))
	  (unless server-process (error "Could not start server process"))
	  (when server-use-tcp
	    (let ((auth-key
		   (loop
		    ;; The auth key is a 64-byte string of random chars in the
		    ;; range `!'..`~'.
		    for i below 64
		    collect (+ 33 (random 94)) into auth
		    finally return (concat auth))))
	      (process-put server-process :auth-key auth-key)
	      (with-temp-file server-file
		(set-buffer-multibyte nil)
		(setq buffer-file-coding-system 'no-conversion)
		(insert (format-network-address
			 (process-contact server-process :local))
			" " (int-to-string (emacs-pid))
			"\n" auth-key)))))))))
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;;;###autoload
(define-minor-mode server-mode
  "Toggle Server mode.
With ARG, turn Server mode on if ARG is positive, off otherwise.
Server mode runs a process that accepts commands from the
`emacsclient' program.  See `server-start' and Info node `Emacs server'."
  :global t
  :group 'server
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  :version "22.1"
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  ;; Fixme: Should this check for an existing server socket and do
  ;; nothing if there is one (for multiple Emacs sessions)?
  (server-start (not server-mode)))
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(defun* server-process-filter (proc string)
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  "Process a request from the server to edit some files.
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PROC is the server process.  STRING consists of a sequence of
commands prefixed by a dash.  Some commands have arguments; these
are &-quoted and need to be decoded by `server-unquote-arg'.  The
filter parses and executes these commands.

To illustrate the protocol, here is an example command that
emacsclient sends to create a new X frame (note that the whole
sequence is sent on a single line):

	-version 21.3.50 xterm
	-env HOME /home/lorentey
	-env DISPLAY :0.0
	... lots of other -env commands
	-display :0.0
	-window-system

The server normally sends back the single command `-good-version'
as a response.

The following commands are accepted by the server:

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`-auth AUTH-STRING'
  Authenticate the client using the secret authentication string
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  AUTH-STRING.
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`-version CLIENT-VERSION'
  Check version numbers between server and client, and signal an
  error if there is a mismatch.  The server replies with
  `-good-version' to confirm the match.

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`-env NAME=VALUE'
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  An environment variable on the client side.

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`-dir DIRNAME'
  The current working directory of the client process.

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`-current-frame'
  Forbid the creation of new frames.

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`-nowait'
  Request that the next frame created should not be
  associated with this client.

`-display DISPLAY'
  Set the display name to open X frames on.

`-position LINE[:COLUMN]'
  Go to the given line and column number
  in the next file opened.

`-file FILENAME'
  Load the given file in the current frame.

`-eval EXPR'
  Evaluate EXPR as a Lisp expression and return the
  result in -print commands.

`-window-system'
  Open a new X frame.

`-tty DEVICENAME TYPE'
  Open a new tty frame at the client.

`-suspend'
  Suspend this tty frame.  The client sends this string in
  response to SIGTSTP and SIGTTOU.  The server must cease all I/O
  on this tty until it gets a -resume command.

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`-resume'
  Resume this tty frame. The client sends this string when it
  gets the SIGCONT signal and it is the foreground process on its
  controlling tty.

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`-ignore COMMENT'
  Do nothing, but put the comment in the server
  log.  Useful for debugging.


The following commands are accepted by the client:

`-good-version'
  Signals a version match between the client and the server.

`-emacs-pid PID'
  Describes the process id of the Emacs process;
  used to forward window change signals to it.

`-window-system-unsupported'
  Signals that the server does not
  support creating X frames; the client must try again with a tty
  frame.

`-print STRING'
  Print STRING on stdout.  Used to send values
  returned by -eval.

`-error DESCRIPTION'
  Signal an error (but continue processing).

`-suspend'
  Suspend this terminal, i.e., stop the client process.  Sent
  when the user presses C-z."
  (server-log (concat "Received " string) proc)
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  ;; First things first: let's check the authentication
  (unless (process-get proc :authenticated)
    (if (and (string-match "-auth \\(.*?\\)\n" string)
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	     (equal (match-string 1 string) (process-get proc :auth-key)))
	(progn
	  (setq string (substring string (match-end 0)))
	  (process-put proc :authenticated t)
	  (server-log "Authentication successful" proc))
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      (server-log "Authentication failed" proc)
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      (server-send-string
       proc (concat "-error " (server-quote-arg "Authentication failed")))
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      (delete-process proc)
      ;; We return immediately
      (return-from server-process-filter)))
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  (when (> (recursion-depth) 0)
    ;; We're inside a minibuffer already, so if the emacs-client is trying
    ;; to open a frame on a new display, we might end up with an unusable
    ;; frame because input from that display will be blocked (until exiting
    ;; the minibuffer).  Better exit this minibuffer right away.
    ;; Similarly with recursive-edits such as the splash screen.
    (process-put proc :previous-string string)
    (run-with-timer 0 nil (lexical-let ((proc proc))
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			    (lambda () (server-process-filter proc ""))))
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    (top-level))
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  (condition-case nil
      ;; If we're running isearch, we must abort it to allow Emacs to
      ;; display the buffer and switch to it.
      (mapc #'(lambda (buffer)
		(with-current-buffer buffer
		  (when (bound-and-true-p isearch-mode)
		    (isearch-cancel))))
	    (buffer-list))
    ;; Signaled by isearch-cancel
    (quit (message nil)))
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  (let ((prev (process-get proc 'previous-string)))
    (when prev
      (setq string (concat prev string))
      (process-put proc 'previous-string nil)))
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  (condition-case err
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      (progn
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	(server-add-client proc)
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	;; If the input is multiple lines,
	;; process each line individually.
	(while (string-match "\n" string)
	  (let ((request (substring string 0 (match-beginning 0)))
		(coding-system (and default-enable-multibyte-characters
				    (or file-name-coding-system
					default-file-name-coding-system)))
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		(client (server-client proc))
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		current-frame
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		nowait ; t if emacsclient does not want to wait for us.
		frame ; The frame that was opened for the client (if any).
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		display		     ; Open the frame on this display.
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		dontkill       ; t if the client should not be killed.
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		env
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		dir
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		(files nil)
		(lineno 1)
		(columnno 0))
	    ;; Remove this line from STRING.
	    (setq string (substring string (match-end 0)))
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	    (while (string-match " *[^ ]* " request)
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	      (let ((arg (substring request (match-beginning 0) (1- (match-end 0)))))
		(setq request (substring request (match-end 0)))
		(cond
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		 ;; -version CLIENT-VERSION:
		 ;; Check version numbers, signal an error if there is a mismatch.
		 ((and (equal "-version" arg)
		       (string-match "\\([0-9.]+\\) " request))
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		  (let* ((client-version (match-string 1 request))
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			 (truncated-emacs-version
			  (substring emacs-version 0 (length client-version))))
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		    (setq request (substring request (match-end 0)))
		    (if (equal client-version truncated-emacs-version)
			(progn
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			  (server-send-string proc "-good-version \n")
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			  (server-client-set client 'version client-version))
		      (error (concat "Version mismatch: Emacs is "
				     truncated-emacs-version
				     ", emacsclient is " client-version)))))
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		 ;; -nowait:  Emacsclient won't wait for a result.
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		 ((equal "-nowait" arg) (setq nowait t))

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		 ;; -current-frame:  Don't create frames.
		 ((equal "-current-frame" arg) (setq current-frame t))

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		 ;; -display DISPLAY:
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		 ;; Open X frames on the given display instead of the default.
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		 ((and (equal "-display" arg) (string-match "\\([^ ]*\\) " request))
		  (setq display (match-string 1 request)
			request (substring request (match-end 0))))

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		 ;; -window-system:  Open a new X frame.
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		 ((equal "-window-system" arg)
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		  (unless (server-client-get client 'version)
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		    (error "Protocol error; make sure to use the correct version of emacsclient"))
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		  (unless current-frame
		    (if (fboundp 'x-create-frame)
			(let ((params (if nowait
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					  ;; Flag frame as client-created, but use a dummy client.
					  ;; This will prevent the frame from being deleted when
					  ;; emacsclient quits while also preventing
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					  ;; `server-save-buffers-kill-terminal' from unexpectedly
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					  ;; killing emacs on that frame.
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					  (list (cons 'client 'nowait) (cons 'environment env))
					(list (cons 'client proc) (cons 'environment env)))))
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			  (setq frame (make-frame-on-display
				       (or display
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					   (frame-parameter nil 'display)
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					   (getenv "DISPLAY")
					   (error "Please specify display"))
				       params))
			  (server-log (format "%s created" frame) proc)
			  ;; XXX We need to ensure the parameters are
			  ;; really set because Emacs forgets unhandled
			  ;; initialization parameters for X frames at
			  ;; the moment.
			  (modify-frame-parameters frame params)
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			  (set-frame-parameter frame 'display-environment-variable 
					       (server-getenv-from env "DISPLAY"))
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			  (select-frame frame)
			  (server-client-set client 'frame frame)
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			  (server-client-set client 'terminal (frame-terminal frame))
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			  ;; Display *scratch* by default.
			  (switch-to-buffer (get-buffer-create "*scratch*") 'norecord)

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			  (setq dontkill t))
		      ;; This emacs does not support X.
		      (server-log "Window system unsupported" proc)
		      (server-send-string proc "-window-system-unsupported \n")
		      (setq dontkill t))))
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		 ;; -resume:  Resume a suspended tty frame.
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		 ((equal "-resume" arg)
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		  (let ((terminal (server-client-get client 'terminal)))
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		    (setq dontkill t)
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		    (when (eq (terminal-live-p terminal) t)
		      (resume-tty terminal))))
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		 ;; -suspend:  Suspend the client's frame.  (In case we
		 ;; get out of sync, and a C-z sends a SIGTSTP to
		 ;; emacsclient.)
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		 ((equal "-suspend" arg)
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		  (let ((terminal (server-client-get client 'terminal)))
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		    (setq dontkill t)
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		    (when (eq (terminal-live-p terminal) t)
		      (suspend-tty terminal))))
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		 ;; -ignore COMMENT:  Noop; useful for debugging emacsclient.
		 ;; (The given comment appears in the server log.)
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		 ((and (equal "-ignore" arg) (string-match "\\([^ ]*\\) " request))
		  (setq dontkill t
			request (substring request (match-end 0))))

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		 ;; -tty DEVICE-NAME TYPE:  Open a new tty frame at the client.
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		 ((and (equal "-tty" arg) (string-match "\\([^ ]*\\) \\([^ ]*\\) " request))
		  (let ((tty (server-unquote-arg (match-string 1 request)))
			(type (server-unquote-arg (match-string 2 request))))
		    (setq request (substring request (match-end 0)))
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		    (unless (server-client-get client 'version)
		      (error "Protocol error; make sure you use the correct version of emacsclient"))
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		    (unless current-frame
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		      (server-with-environment env
			  '("LANG" "LC_CTYPE" "LC_ALL"
			    ;; For tgetent(3); list according to ncurses(3).
			    "BAUDRATE" "COLUMNS" "ESCDELAY" "HOME" "LINES"
			    "NCURSES_ASSUMED_COLORS" "NCURSES_NO_PADDING"
			    "NCURSES_NO_SETBUF" "TERM" "TERMCAP" "TERMINFO"
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			    "TERMINFO_DIRS" "TERMPATH" 
			    ;; rxvt wants these
			    "COLORFGBG" "COLORTERM")
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			(setq frame (make-frame-on-tty tty type
						       ;; Ignore nowait here; we always need to clean
						       ;; up opened ttys when the client dies.
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						       `((client . ,proc)
							 (environment . ,env)))))
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		      (set-frame-parameter frame 'display-environment-variable 
					   (server-getenv-from env "DISPLAY"))
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		      (select-frame frame)
		      (server-client-set client 'frame frame)
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		      (server-client-set client 'tty (terminal-name frame))
		      (server-client-set client 'terminal (frame-terminal frame))
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		      ;; Display *scratch* by default.
		      (switch-to-buffer (get-buffer-create "*scratch*") 'norecord)

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		      ;; Reply with our pid.
		      (server-send-string proc (concat "-emacs-pid " (number-to-string (emacs-pid)) "\n"))
		      (setq dontkill t))))
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		 ;; -position LINE:  Go to the given line in the next file.
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		 ((and (equal "-position" arg) (string-match "\\(\\+[0-9]+\\) " request))
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		  (setq lineno (string-to-number (substring (match-string 1 request) 1))
			request (substring request (match-end 0))))
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		 ;; -position LINE:COLUMN:  Set point to the given position in the next file.
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		 ((and (equal "-position" arg) (string-match "\\+\\([0-9]+\\):\\([0-9]+\\) " request))
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		  (setq lineno (string-to-number (match-string 1 request))
			columnno (string-to-number (match-string 2 request))
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			request (substring request (match-end 0))))
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		 ;; -file FILENAME:  Load the given file.
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		 ((and (equal "-file" arg) (string-match "\\([^ ]+\\) " request))
		  (let ((file (server-unquote-arg (match-string 1 request))))
		    (setq request (substring request (match-end 0)))
		    (if coding-system
			(setq file (decode-coding-string file coding-system)))
		    (setq file (command-line-normalize-file-name file))
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		    (push (list file lineno columnno) files)
		    (server-log (format "New file: %s (%d:%d)" file lineno columnno) proc))
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		  (setq lineno 1
			columnno 0))

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		 ;; -eval EXPR:  Evaluate a Lisp expression.
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		 ((and (equal "-eval" arg) (string-match "\\([^ ]+\\) " request))
		  (let ((expr (server-unquote-arg (match-string 1 request))))
		    (setq request (substring request (match-end 0)))
		    (if coding-system
			(setq expr (decode-coding-string expr coding-system)))
		    (let ((v (eval (car (read-from-string expr)))))
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		      (when (and (not frame) v)
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			(with-temp-buffer
			  (let ((standard-output (current-buffer)))
			    (pp v)
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			    (server-send-string
			     proc (format "-print %s\n"
					  (server-quote-arg
					   (buffer-substring-no-properties (point-min)
									   (point-max)))))))))
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		    (setq lineno 1
			  columnno 0)))

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		 ;; -env NAME=VALUE:  An environment variable.
		 ((and (equal "-env" arg) (string-match "\\([^ ]+\\) " request))
		  (let ((var (server-unquote-arg (match-string 1 request))))
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		    ;; XXX Variables should be encoded as in getenv/setenv.
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		    (setq request (substring request (match-end 0)))
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		    (setq env (cons var env))))
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		 ;; -dir DIRNAME:  The cwd of the emacsclient process.
		 ((and (equal "-dir" arg) (string-match "\\([^ ]+\\) " request))
		  (setq dir (server-unquote-arg (match-string 1 request)))
		  (setq request (substring request (match-end 0)))
		  (if coding-system
		      (setq dir (decode-coding-string dir coding-system)))
		  (setq dir (command-line-normalize-file-name dir)))

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		 ;; Unknown command.
		 (t (error "Unknown command: %s" arg)))))

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	    (let (buffers)
	      (when files
		(run-hooks 'pre-command-hook)
		(setq buffers (server-visit-files files client nowait))
		(run-hooks 'post-command-hook))

	      ;; Delete the client if necessary.
	      (cond
	       (nowait
		;; Client requested nowait; return immediately.
		(server-log "Close nowait client" proc)
		(server-delete-client proc))
	       ((and (not dontkill) (null buffers))
		;; This client is empty; get rid of it immediately.
		(server-log "Close empty client" proc)
		(server-delete-client proc)))
	      (cond
	       ((or isearch-mode (minibufferp))
		nil)
	       ((and frame (null buffers))
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		(message "%s" (substitute-command-keys
			       "When done with this frame, type \\[delete-frame]")))
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	       ((not (null buffers))
		(server-switch-buffer (car buffers))
		(run-hooks 'server-switch-hook)
		(unless nowait
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		  (message "%s" (substitute-command-keys
				 "When done with a buffer, type \\[server-edit]"))))))))
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	;; Save for later any partial line that remains.
	(when (> (length string) 0)
	  (process-put proc 'previous-string string)))
    ;; condition-case
    (error (ignore-errors
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	     (server-send-string
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	      proc (concat "-error " (server-quote-arg (error-message-string err))))
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	     (setq string "")
	     (server-log (error-message-string err) proc)
	     (delete-process proc)))))
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(defun server-goto-line-column (file-line-col)
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  "Move point to the position indicated in FILE-LINE-COL.
FILE-LINE-COL should be a three-element list as described in
`server-visit-files'."
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  (goto-line (nth 1 file-line-col))
  (let ((column-number (nth 2 file-line-col)))
    (if (> column-number 0)
	(move-to-column (1- column-number)))))

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(defun server-visit-files (files client &optional nowait)
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  "Find FILES and return a list of buffers created.
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FILES is an alist whose elements are (FILENAME LINENUMBER COLUMNNUMBER).
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CLIENT is the client that requested this operation.
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NOWAIT non-nil means this client is not waiting for the results,
so don't mark these buffers specially, just visit them normally."
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  ;; Bind last-nonmenu-event to force use of keyboard, not mouse, for queries.
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  (let ((last-nonmenu-event t) client-record)
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    ;; 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.
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    (save-current-buffer
      (dolist (file 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.
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	(let* ((minibuffer-auto-raise (or server-raise-frame
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					  minibuffer-auto-raise))
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	       (filen (car file))
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	       (obuf (get-file-buffer filen)))
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	  (add-to-history 'file-name-history filen)
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	  (if (and obuf (set-buffer obuf))
	      (progn
		(cond ((file-exists-p filen)
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		       (when (not (verify-visited-file-modtime obuf))
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			 (revert-buffer t nil)))
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		      (t
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		       (when (y-or-n-p
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			      (concat "File no longer exists: " filen
				      ", write buffer to file? "))
			 (write-file filen))))
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		(unless server-buffer-clients
		  (setq server-existing-buffer t))
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		(server-goto-line-column file))
	    (set-buffer (find-file-noselect filen))
	    (server-goto-line-column file)
	    (run-hooks 'server-visit-hook)))
	(unless nowait
	  ;; When the buffer is killed, inform the clients.
	  (add-hook 'kill-buffer-hook 'server-kill-buffer nil t)
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