;;; resume.el --- process command line args from within a suspended Emacs job
;; Copyright (C) 1992 Free Software Foundation, Inc.
;; Author: Joe Wells <firstname.lastname@example.org>
;; Adapted-By: ESR
;; Keywords: processes
;; 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, 675 Mass Ave, Cambridge, MA 02139, USA.
;; Theory: the first time you start Emacs, command line arguments are
;; handled normally. Then, you suspend your emacs job. When you want to edit
;; something else, you type "emacs filename" as usual, but instead of
;; starting a new emacs job, the old job is resumed instead, and the command
;; line arguments are placed in a file where the old emacs job looks for
;; Stephan Gildea suggested bug fix (email@example.com).
;; Ideas from Michael DeCorte and other people.
;; For csh users, insert the following alias in your .cshrc file
;; (after removing the leading double semicolons, of course):
;;# The following line could be just EMACS_CMD=emacs, but this depends on
;;# your site.
;;if (! $?EMACS_CMD) set EMACS_CMD=emacs
;;set STOP_PATT='^\[[0-9]*\] *[ +-] Stopped ............ '
;;set SUNVIEW_CMD='emacstool -nw -f emacstool-init -f server-start'
;;set X_CMD=\'\''$EMACS_CMD -i -f server-start'
;;alias emacs \
;; jobs >! "$JOBS_FILE" \\
;; && grep "$STOP_PATT$EMACS_CMD" "$JOBS_FILE" >& /dev/null \\
;; && echo `pwd` \!* >! "$ARGS_FILE" && ""fg %$EMACS_CMD \\
;;|| if (! -e ~/.emacs_server || -f ~/.emacs_server) set status=1 \\
;; && emacsclient \!* \\
;;|| @ status=1 - $?DISPLAY && eval "$X_CMD -i \!* &" \\
;;|| @ status=1 - $?WINDOW_PARENT && eval "$SUNVIEW_CMD \!* &" \\
;;|| ""$EMACS_CMD -nw \!* \\
;; The alias works as follows:
;; 1. If there is a suspended Emacs job that is a child of the
;; current shell, place its arguments in the ~/.emacs_args file and
;; resume it.
;; 2. Else if the ~/.emacs_server socket has been created, presume an
;; Emacs server is running and attempt to connect to it. If no Emacs
;; server is listening on the socket, this will fail.
;; 3. Else if the DISPLAY environment variable is set, presume we are
;; running under X Windows and start a new GNU Emacs process in the
;; background as an X client.
;; 4. Else if the WINDOW_PARENT environment variable is set, presume we
;; are running under SunView and start an emacstool process in the
;; 5. Else start a regular Emacs process.
;; The output of the "jobs" command is not piped directly into "grep"
;; because that would run the "jobs" command in a subshell.
;; Before resuming a suspended emacs, the current directory and all
;; command line arguments are placed in a file name ~/.emacs_args.
;; The "-nw" switch to Emacs means no windowing system.
;; Insert this in your .emacs file:
;;(add-hook 'suspend-hook 'resume-suspend-hook)
;; Finally, put the rest in a file named "resume.el" in a lisp library
(defvar resume-emacs-args-file (expand-file-name "~/.emacs_args")
"*This file is where arguments are placed for a suspended emacs job.")
(defvar resume-emacs-args-buffer " *Command Line Args*"
"Buffer that is used by resume-process-args.")
(defun resume-process-args ()
"Handler for command line args given when Emacs is resumed."
(let ((start-buffer (current-buffer))
(args-buffer (get-buffer-create resume-emacs-args-buffer))
;; get the contents of resume-emacs-args-file
(let ((result (insert-file-contents resume-emacs-args-file)))
(setq length (car (cdr result))))
;; the file doesn't exist, ergo no arguments
(setq length 0)))
(if (<= length 0)
(setq args nil)
;; get the arguments from the buffer
(while (not (eobp))
(skip-chars-forward " \t\n")
(let ((begin (point)))
(skip-chars-forward "^ \t\n")
(setq args (cons (buffer-substring begin (point)) args)))
(skip-chars-forward " \t\n"))
;; arguments are now in reverse order
(setq args (nreverse args))
;; make sure they're not read again
(resume-write-buffer-to-file (current-buffer) resume-emacs-args-file)
;; if nothing was in buffer, args will be null
(or (null args)
(file-name-as-directory (car args))
args (cdr args)))
;; actually process the arguments
;; If the command line args don't result in a find-file, the
;; buffer will be left in args-buffer. So we change back to the
;; original buffer. The reason I don't just use
;; (let ((default-directory foo))
;; (command-line-1 args))
;; in the context of the original buffer is because let does not
;; work properly with buffer-local variables.
(if (eq (current-buffer) args-buffer)
(defun resume-suspend-hook ()
"Clear out the file used for transmitting args when Emacs resumes."
(set-buffer (get-buffer-create resume-emacs-args-buffer))
(resume-write-buffer-to-file (current-buffer) resume-emacs-args-file)))
(defun resume-write-buffer-to-file (buffer file)
"Writes the contents of BUFFER into FILE, if permissions allow."
(if (not (file-writable-p file))
(error "No permission to write file %s" file))
(write-region (point-min) (point-max) file nil 'quiet))
;;; resume.el ends here