1;;; resume.el --- process command line args from within a suspended Emacs job
2
3;; Copyright (C) 1992, 2001, 2002, 2003, 2004, 2005,
4;;   2006, 2007 Free Software Foundation, Inc.
5
6;; Author: Joe Wells <jbw@bucsf.bu.edu>
7;; Adapted-By: ESR
8;; Keywords: processes
9
10;; This file is part of GNU Emacs.
11
12;; GNU Emacs is free software; you can redistribute it and/or modify
13;; it under the terms of the GNU General Public License as published by
14;; the Free Software Foundation; either version 2, or (at your option)
15;; any later version.
16
17;; GNU Emacs is distributed in the hope that it will be useful,
18;; but WITHOUT ANY WARRANTY; without even the implied warranty of
19;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
20;; GNU General Public License for more details.
21
22;; You should have received a copy of the GNU General Public License
23;; along with GNU Emacs; see the file COPYING.  If not, write to the
24;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
25;; Boston, MA 02110-1301, USA.
26
27;;; Commentary:
28
29;; The purpose of this library is to handle command line arguments
30;; when you resume an existing Emacs job.
31
32;; In order to use it, you must put this code in your .emacs file.
33
34;; (add-hook 'suspend-hook 'resume-suspend-hook)
35;; (add-hook 'suspend-resume-hook 'resume-process-args)
36
37;; You can't get the benefit of this library by using the `emacs' command,
38;; since that always starts a new Emacs job.  Instead you must use a
39;; command called `edit' which knows how to resume an existing Emacs job
40;; if you have one, or start a new Emacs job if you don't have one.
41
42;; To define the `edit' command, run the script etc/emacs.csh (if you use CSH),
43;; or etc/emacs.bash if you use BASH.  You would normally do this in your
44;; login script.
45
46;; Stephan Gildea suggested bug fix (gildea@bbn.com).
47;; Ideas from Michael DeCorte and other people.
48
49;;; Code:
50
51(defvar resume-emacs-args-file (expand-file-name "~/.emacs_args")
52  "*This file is where arguments are placed for a suspended Emacs job.")
53
54(defvar resume-emacs-args-buffer " *Command Line Args*"
55  "Buffer that is used by `resume-process-args'.")
56
57(defun resume-process-args ()
58  "Handler for command line args given when Emacs is resumed."
59  (let ((start-buffer (current-buffer))
60	(args-buffer (get-buffer-create resume-emacs-args-buffer))
61	length args
62	(command-line-default-directory default-directory))
63    (unwind-protect
64	(progn
65	  (set-buffer args-buffer)
66	  (erase-buffer)
67	  ;; get the contents of resume-emacs-args-file
68	  (condition-case ()
69	      (let ((result (insert-file-contents resume-emacs-args-file)))
70		(setq length (car (cdr result))))
71	    ;; the file doesn't exist, ergo no arguments
72	    (file-error
73	      (erase-buffer)
74	      (setq length 0)))
75	  (if (<= length 0)
76	      (setq args nil)
77	    ;; get the arguments from the buffer
78	    (goto-char (point-min))
79	    (while (not (eobp))
80	      (skip-chars-forward " \t\n")
81	      (let ((begin (point)))
82		(skip-chars-forward "^ \t\n")
83		(setq args (cons (buffer-substring begin (point)) args)))
84	      (skip-chars-forward " \t\n"))
85	    ;; arguments are now in reverse order
86	    (setq args (nreverse args))
87	    ;; make sure they're not read again
88	    (erase-buffer))
89	  (resume-write-buffer-to-file (current-buffer) resume-emacs-args-file)
90	  ;; if nothing was in buffer, args will be null
91	  (or (null args)
92	      (setq command-line-default-directory
93		    (file-name-as-directory (car args))
94		    args (cdr args)))
95	  ;; actually process the arguments
96	  (command-line-1 args))
97      ;; If the command line args don't result in a find-file, the
98      ;; buffer will be left in args-buffer.  So we change back to the
99      ;; original buffer.  The reason I don't just use
100      ;; (let ((default-directory foo))
101      ;;    (command-line-1 args))
102      ;; in the context of the original buffer is because let does not
103      ;; work properly with buffer-local variables.
104      (if (eq (current-buffer) args-buffer)
105	  (set-buffer start-buffer)))))
106
107;;;###autoload
108(defun resume-suspend-hook ()
109  "Clear out the file used for transmitting args when Emacs resumes."
110  (save-excursion
111    (set-buffer (get-buffer-create resume-emacs-args-buffer))
112    (erase-buffer)
113    (resume-write-buffer-to-file (current-buffer) resume-emacs-args-file)))
114
115(defun resume-write-buffer-to-file (buffer file)
116  "Writes the contents of BUFFER into FILE, if permissions allow."
117  (if (not (file-writable-p file))
118      (error "No permission to write file %s" file))
119  (save-excursion
120    (set-buffer buffer)
121    (clear-visited-file-modtime)
122    (save-restriction
123      (widen)
124      (write-region (point-min) (point-max) file nil 'quiet))
125    (set-buffer-modified-p nil)))
126
127(provide 'resume)
128
129;;; arch-tag: c90b2761-4803-4e58-a0ae-c4721368b628
130;;; resume.el ends here
131