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;; Emacs edit-server
;; This provides an edit server to respond to requests from the Chrome
;; Emacs Chrome plugin. This is my first attempt at doing something
;; with sockets in Emacs. I based it on the following examples:
;; To use it ensure the file is in your load-path and add something
;; like:
;; (if (and (daemonp) (locate-library "edit-server"))
;; (progn
;; (require 'edit-server)
;; (edit-server-start)))
;; (C) 2009 Alex Bennee (
;; (C) 2010 Riccardo Murri (
;; Licensed under GPLv3
;; uncomment to debug
;(setq debug-on-error 't)
;(setq edebug-all-defs 't)
;; Customization
(defcustom edit-server-port 9292
"Local port the edit server listens to."
:group 'edit-server
:type 'integer)
(defcustom edit-server-new-frame t
"If not nil, edit each buffer in a new frame (and raise it)."
:group 'edit-server
:type 'boolean)
(defcustom edit-server-verbose nil
"If not nil, log connections and progress also to the echo area."
:group 'edit-server
:type 'boolean)
(defcustom edit-server-done-hook nil
"Hook run when done editing a buffer for the Emacs HTTP edit-server.
Current buffer holds the text that is about to be sent back to the client."
:group 'edit-server
:type 'hook)
;; Vars
(defconst edit-server-process-buffer-name " *edit-server*"
"Template name of the edit-server process buffers.")
(defconst edit-server-log-buffer-name "*edit-server-log*"
"Template name of the edit-server process buffers.")
(defconst edit-server-edit-buffer-name "TEXTAREA"
"Template name of the edit-server text editing buffers.")
(defconst edit-server-new-frame-title "Emacs TEXTAREA"
"Template name of the emacs frame's title.")
(defconst edit-server-new-frame-width 80
"The emacs frame's width.")
(defconst edit-server-new-frame-height 25
"The emacs frame's height.")
(defvar edit-server-proc 'nil
"Network process associated with the current edit, made local when
the edit buffer is created")
(defvar edit-server-frame 'nil
"The frame created for a new edit-server process, made local when
then edit buffer is created")
(defvar edit-server-clients '()
"List of all client processes associated with the server process.")
(defvar edit-server-phase nil
"Symbol indicating the state of the HTTP request parsing.")
(defvar edit-server-received nil
"Number of bytes received so far in the client buffer.
Depending on the character encoding, may be different from the buffer length.")
(defvar edit-server-request nil
"The HTTP request (GET, HEAD, POST) received.")
(defvar edit-server-content-length nil
"The value gotten from the HTTP `Content-Length' header.")
;; Mode magic
; We want to re-map some of the keys to trigger edit-server-done
; instead of the usual emacs like behaviour. However using
; local-set-key will affect all buffers of the same mode, hence we
; define a special (derived) mode for handling editing of text areas.
(define-derived-mode edit-server-text-mode text-mode "Edit Server Text Mode"
"A derived version of text-mode with a few common Emacs keystrokes
rebound to more functions that can deal with the response to the
edit-server request.
Any of the following keys will close the buffer and send the text
to the HTTP client: C-x #, C-x C-s, C-c C-c.
If any of the above isused with a prefix argument, the
unmodified text is sent back instead.
:group 'edit-server)
(define-key edit-server-text-mode-map (kbd "C-x #") 'edit-server-done)
(define-key edit-server-text-mode-map (kbd "C-x C-s") 'edit-server-done)
(define-key edit-server-text-mode-map (kbd "C-c C-c") 'edit-server-done)
(define-key edit-server-text-mode-map (kbd "C-x C-c") 'edit-server-abort)
;; Edit Server socket code
(defun edit-server-start (&optional verbose)
"Start the edit server.
If argument VERBOSE is non-nil, logs all server activity to buffer `*edit-server-log*'.
When called interactivity, a prefix argument will cause it to be verbose.
(interactive "P")
(if (process-status "edit-server")
(message "An edit-server process is already running")
:name "edit-server"
:buffer edit-server-process-buffer-name
:family 'ipv4
:host 'local ; only listen to local connections
:service edit-server-port
:log 'edit-server-accept
:server 't)
(setq edit-server-clients '())
(if verbose (get-buffer-create edit-server-log-buffer-name))
(edit-server-log nil "Created a new edit-server process")))
(defun edit-server-stop nil
"Stop the edit server"
(while edit-server-clients
(edit-server-kill-client (car edit-server-clients))
(setq edit-server-clients (cdr edit-server-clients)))
(if (process-status "edit-server")
(delete-process "edit-server")
(message "No edit server running"))
(if (get-buffer edit-server-process-buffer-name)
(kill-buffer edit-server-process-buffer-name)))
(defun edit-server-log (proc fmt &rest args)
"If a `*edit-server-log*' buffer exists, write STRING to it for logging purposes.
If `edit-server-verbose' is non-nil, then STRING is also echoed to the message line."
(let ((string (apply 'format fmt args)))
(if edit-server-verbose
(message string))
(if (get-buffer edit-server-log-buffer-name)
(with-current-buffer edit-server-log-buffer-name
(goto-char (point-max))
(insert (current-time-string)
" "
(if (processp proc)
(buffer-name (process-buffer proc))
": ")
"") ; nil is not acceptable to 'insert
(or (bolp) (newline))))))
(defun edit-server-accept (server client msg)
"Accept a new client connection."
(let ((buffer (generate-new-buffer edit-server-process-buffer-name)))
(buffer-disable-undo buffer)
(set-process-buffer client buffer)
(set-process-filter client 'edit-server-filter)
(set-process-query-on-exit-flag client nil) ; kill-buffer kills the associated process
(with-current-buffer buffer
(set (make-local-variable 'edit-server-phase) 'wait)
(set (make-local-variable 'edit-server-received) 0)
(set (make-local-variable 'edit-server-request) nil))
(set (make-local-variable 'edit-server-content-length) nil))
(add-to-list 'edit-server-clients client)
(edit-server-log client msg))
(defun edit-server-filter (proc string)
"Process data received from the client."
;; there is no guarantee that data belonging to the same client
;; request will arrive all in one go; therefore, we must accumulate
;; data in the buffer and process it in different phases, which
;; requires us to keep track of the processing state.
(with-current-buffer (process-buffer proc)
(insert string)
(setq edit-server-received
(+ edit-server-received (string-bytes string)))
(when (eq edit-server-phase 'wait)
;; look for a complete HTTP request string
(goto-char (point-min))
(when (re-search-forward "^\\([A-Z]+\\)\\s-+\\(\\S-+\\)\\s-+\\(HTTP/[0-9\.]+\\)\r?\n" nil t)
(edit-server-log proc
"Got HTTP `%s' request, processing in buffer `%s'..."
(match-string 1) (current-buffer))
(setq edit-server-request (match-string 1))
(setq edit-server-content-length nil)
(setq edit-server-phase 'head))))
(when (eq edit-server-phase 'head)
;; look for "Content-length" header
(goto-char (point-min))
(when (re-search-forward "^Content-Length:\\s-+\\([0-9]+\\)" nil t)
(setq edit-server-content-length (string-to-number (match-string 1)))))
;; look for head/body separator
(goto-char (point-min))
(when (re-search-forward "\\(\r?\n\\)\\{2\\}" nil t)
;; HTTP headers are pure ASCII (1 char = 1 byte), so we can subtract
;; the buffer position from the count of received bytes
(setq edit-server-received
(- edit-server-received (- (match-end 0) (point-min))))
;; discard headers - keep only HTTP content in buffer
(delete-region (point-min) (match-end 0))
(setq edit-server-phase 'body))))
(when (eq edit-server-phase 'body)
(if (and edit-server-content-length
(> edit-server-content-length edit-server-received))
(edit-server-log proc
"Received %d bytes of %d ..."
edit-server-received edit-server-content-length)
;; all content transferred - process request now
((string= edit-server-request "POST")
;; create editing buffer, and move content to it
(edit-server-create-edit-buffer proc))
;; send 200 OK response to any other request
(edit-server-send-response proc "edit-server is running.\n" t)))
;; wait for another connection to arrive
(setq edit-server-received 0)
(setq edit-server-phase 'wait)))))
(defun edit-server-create-edit-buffer(proc)
"Create an edit buffer, place content in it and save the network
process for the final call back"
(let ((buffer (generate-new-buffer edit-server-edit-buffer-name)))
(copy-to-buffer buffer (point-min) (point-max))
(with-current-buffer buffer
(add-hook 'kill-buffer-hook 'edit-server-abort* nil t)
(set (make-local-variable 'edit-server-proc) proc)
(set (make-local-variable 'edit-server-frame)
(if edit-server-new-frame
(make-frame-on-display (getenv "DISPLAY")
`((name . ,edit-server-new-frame-title) (width . ,edit-server-new-frame-width) (height . ,edit-server-new-frame-height)))
(if edit-server-new-frame
(raise-frame edit-server-frame)
(pop-to-buffer buffer)))))
(defun edit-server-send-response (proc &optional body close)
"Send an HTTP 200 OK response back to process PROC.
Optional second argument BODY specifies the response content:
- If nil, the HTTP response will have null content.
- If a string, the string is sent as response content.
- Any other value will cause the contents of the current
buffer to be sent.
If optional third argument CLOSE is non-nil, then process PROC
and its buffer are killed with `edit-server-kill-client'."
(if (processp proc)
(let ((response-header (concat
"HTTP/1.0 200 OK\n"
"Server: Emacs\n"
"Date: "
"%a, %d %b %Y %H:%M:%S GMT\n"
(process-send-string proc response-header)
(process-send-string proc "\n")
((stringp body) (process-send-string proc body))
((not body) nil)
(t (process-send-region proc (point-min) (point-max))))
(process-send-eof proc)
(if close
(edit-server-kill-client proc))
(edit-server-log proc "Editing done, sent HTTP OK response."))
(message "edit-server-send-response: invalid proc (bug?)")))
(defun edit-server-kill-client (proc)
"Kill client process PROC and remove it from the list."
(let ((procbuf (process-buffer proc)))
(delete-process proc)
(kill-buffer procbuf)
(setq edit-server-clients (delq procbuf edit-server-clients))))
(defun edit-server-done (&optional abort nokill)
"Finish editing: send HTTP response back, close client and editing buffers.
The current contents of the buffer are sent back to the HTTP
client, unless argument ABORT is non-nil, in which case then the
original text is sent back.
If optional second argument NOKILL is non-nil, then the editing
buffer is not killed.
When called interactively, use prefix arg to abort editing."
(interactive "P")
(let ((buffer (current-buffer))
(proc edit-server-proc)
(procbuf (process-buffer edit-server-proc)))
;; edit-server-* vars are buffer-local, so they must be used before issuing kill-buffer
(if abort
;; send back original content
(with-current-buffer procbuf
(run-hooks 'edit-server-done-hook)
(edit-server-send-response proc t))
;; send back edited content
;; ensure any format encoding is done (like longlines)
(dolist (format buffer-file-format)
(format-encode-region (point-min) (point-max) format))
;; send back
(run-hooks 'edit-server-done-hook)
(edit-server-send-response edit-server-proc t)
;; restore formats (only useful if we keep the buffer)
(dolist (format buffer-file-format)
(format-decode-region (point-min) (point-max) format))
(if edit-server-frame (delete-frame edit-server-frame))
;; delete-frame may change the current buffer
(unless nokill (kill-buffer buffer))
(edit-server-kill-client proc)))
(defun edit-server-abort ()
"Discard editing and send the original text back to the browser."
(edit-server-done t))
(defun edit-server-abort* ()
"Discard editing and send the original text back to the browser,
but don't kill the editing buffer."
(edit-server-done t t))
(provide 'edit-server)
;;; edit-server.el ends here
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