1 ;;; -*- no-byte-compile: t; -*-
2 ;;; dbus.el --- Elisp bindings for D-Bus.
4 ;; Copyright (C) 2007 Free Software Foundation, Inc.
6 ;; Author: Michael Albinus <michael.albinus@gmx.de>
7 ;; Keywords: comm, hardware
9 ;; This file is part of GNU Emacs.
11 ;; GNU Emacs is free software; you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation; either version 3, or (at your option)
16 ;; GNU Emacs is distributed in the hope that it will be useful,
17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ;; GNU General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs; see the file COPYING. If not, see
23 ;; <http://www.gnu.org/licenses/>.
27 ;; This package provides language bindings for the D-Bus API. D-Bus
28 ;; is a message bus system, a simple way for applications to talk to
29 ;; one another. See <http://dbus.freedesktop.org/> for details.
31 ;; Low-level language bindings are implemented in src/dbusbind.c.
37 (defconst dbus-service-dbus
"org.freedesktop.DBus"
38 "The bus name used to talk to the bus itself.")
40 (defconst dbus-path-dbus
"/org/freedesktop/DBus"
41 "The object path used to talk to the bus itself.")
43 (defconst dbus-interface-dbus
"org.freedesktop.DBus"
44 "The interface exported by the object with `dbus-service-dbus' and `dbus-path-dbus'.")
46 (defconst dbus-interface-introspectable
"org.freedesktop.DBus.Introspectable"
47 "The interface supported by introspectable objects.")
50 ;;; Hash table of registered functions.
52 ;; We create it here. So we have a simple test in dbusbind.c, whether
53 ;; the Lisp code has been loaded.
54 (setq dbus-registered-functions-table
(make-hash-table :test
'equal
))
56 (defun dbus-list-hash-table ()
57 "Returns all registered signal registrations to D-Bus.
58 The return value is a list, with elements of kind (KEY . VALUE).
59 See `dbus-registered-functions-table' for a description of the
63 '(lambda (key value
) (add-to-list 'result
(cons key value
) 'append
))
64 dbus-registered-functions-table
)
67 (defun dbus-name-owner-changed-handler (service old-owner new-owner
)
68 "Reapplies all signal registrations to D-Bus.
69 This handler is applied when a \"NameOwnerChanged\" signal has
70 arrived. SERVICE is the object name for which the name owner has
71 been changed. OLD-OWNER is the previous owner of SERVICE, or the
72 empty string if SERVICE was not owned yet. NEW-OWNER is the new
73 owner of SERVICE, or the empty string if SERVICE looses any name owner."
75 ;; Check whether SERVICE is a known name.
76 (when (and (stringp service
) (not (string-match "^:" service
))
77 (stringp old-owner
) (stringp new-owner
))
81 ;; key has the structure (BUS INTERFACE SIGNAL).
82 ;; elt has the structure (SERVICE UNAME PATH HANDLER).
83 (when (string-equal old-owner
(cadr elt
))
84 ;; Remove old key, and add new entry with changed name.
85 (when dbus-debug
(message "Remove rule for %s %s" key elt
))
86 ;(dbus-unregister-signal key)
87 (setcar (cdr elt
) new-owner
)
88 (when dbus-debug
(message "Add rule for %s %s" key elt
))
89 ;; Maybe we could arrange the lists a little bit better
90 ;; that we don't need to extract every single element?
91 (when (not (zerop (length new-owner
)))
94 (nth 0 key
) (nth 0 elt
) (nth 2 elt
)
95 ;; INTERFACE SIGNAL HANDLER
96 (nth 1 key
) (nth 2 key
) (nth 3 elt
))))))
97 (copy-hash-table dbus-registered-functions-table
)))))
99 ;; Register the handler.
102 (dbus-register-signal
103 :system dbus-service-dbus dbus-path-dbus dbus-interface-dbus
104 "NameOwnerChanged" 'dbus-name-owner-changed-handler
)
105 (dbus-register-signal
106 :session dbus-service-dbus dbus-path-dbus dbus-interface-dbus
107 "NameOwnerChanged" 'dbus-name-owner-changed-handler
))
113 (defun dbus-check-event (event)
114 "Checks whether EVENT is a well formed D-Bus event.
115 EVENT is a list which starts with symbol `dbus-event':
117 (dbus-event BUS SERVICE PATH INTERFACE MEMBER HANDLER &rest ARGS)
119 BUS identifies the D-Bus the signal is coming from. It is either
120 the symbol `:system' or the symbol `:session'. SERVICE and PATH
121 are the unique name and the object path of the D-Bus object
122 emitting the signal. INTERFACE and MEMBER denote the signal
123 which has been sent. HANDLER is the function which has been
124 registered for this signal. ARGS are the arguments passed to
125 HANDLER, when it is called during event handling in
128 This function raises a `dbus-error' signal in case the event is
130 (when dbus-debug
(message "DBus-Event %s" event
))
131 (unless (and (listp event
)
132 (eq (car event
) 'dbus-event
)
134 (symbolp (nth 1 event
))
136 (stringp (nth 2 event
))
138 (stringp (nth 3 event
))
140 (stringp (nth 4 event
))
142 (stringp (nth 5 event
))
144 (functionp (nth 6 event
)))
145 (signal 'dbus-error
(list "Not a valid D-Bus event" event
))))
148 (defun dbus-handle-event (event)
149 "Handle events from the D-Bus.
150 EVENT is a D-Bus event, see `dbus-check-event'. HANDLER, being
151 part of the event, is called with arguments ARGS."
153 ;; We don't want to raise an error, because this function is called
154 ;; in the event handling loop.
157 (dbus-check-event event
)
158 (apply (nth 6 event
) (nthcdr 7 event
)))
161 (defun dbus-event-bus-name (event)
162 "Return the bus name the event is coming from.
163 The result is either the symbol `:system' or the symbol `:session'.
164 EVENT is a D-Bus event, see `dbus-check-event'. This function
165 raises a `dbus-error' signal in case the event is not well
167 (dbus-check-event event
)
170 (defun dbus-event-service-name (event)
171 "Return the name of the D-Bus object the event is coming from.
172 The result is a string. EVENT is a D-Bus event, see `dbus-check-event'.
173 This function raises a `dbus-error' signal in case the event is
175 (dbus-check-event event
)
178 (defun dbus-event-path-name (event)
179 "Return the object path of the D-Bus object the event is coming from.
180 The result is a string. EVENT is a D-Bus event, see `dbus-check-event'.
181 This function raises a `dbus-error' signal in case the event is
183 (dbus-check-event event
)
186 (defun dbus-event-interface-name (event)
187 "Return the interface name of the D-Bus object the event is coming from.
188 The result is a string. EVENT is a D-Bus event, see `dbus-check-event'.
189 This function raises a `dbus-error' signal in case the event is
191 (dbus-check-event event
)
194 (defun dbus-event-member-name (event)
195 "Return the member name the event is coming from.
196 It is either a signal name or a method name. The result is is a
197 string. EVENT is a D-Bus event, see `dbus-check-event'. This
198 function raises a `dbus-error' signal in case the event is not
200 (dbus-check-event event
)
204 ;;; D-Bus registered names.
206 (defun dbus-list-activatable-names ()
207 "Return the D-Bus service names which can be activated as list.
208 The result is a list of strings, which is nil when there are no
209 activatable service names at all."
212 :system dbus-service-dbus
213 dbus-path-dbus dbus-interface-dbus
"ListActivatableNames")
216 (defun dbus-list-names (bus)
217 "Return the service names registered at D-Bus BUS.
218 The result is a list of strings, which is nil when there are no
219 registered service names at all. Well known names are strings like
220 \"org.freedesktop.DBus\". Names starting with \":\" are unique names
224 bus dbus-service-dbus dbus-path-dbus dbus-interface-dbus
"ListNames")
227 (defun dbus-list-known-names (bus)
228 "Retrieve all services which correspond to a known name in BUS.
229 A service has a known name if it doesn't start with \":\"."
231 (dolist (name (dbus-list-names bus
) result
)
232 (unless (string-equal ":" (substring name
0 1))
233 (add-to-list 'result name
'append
)))))
235 (defun dbus-list-queued-owners (bus service
)
236 "Return the unique names registered at D-Bus BUS and queued for SERVICE.
237 The result is a list of strings, or nil when there are no queued name
238 owners service names at all."
241 bus dbus-service-dbus dbus-path-dbus
242 dbus-interface-dbus
"ListQueuedOwners" service
)
245 (defun dbus-get-name-owner (bus service
)
246 "Return the name owner of SERVICE registered at D-Bus BUS.
247 The result is either a string, or nil if there is no name owner."
250 bus dbus-service-dbus dbus-path-dbus
251 dbus-interface-dbus
"GetNameOwner" service
)
254 (defun dbus-introspect (bus service path
)
255 "Return the introspection data of SERVICE in D-Bus BUS at object path PATH.
256 The data are in XML format.
261 :system \"org.freedesktop.Hal\"
262 \"/org/freedesktop/Hal/devices/computer\")"
265 bus service path dbus-interface-introspectable
"Introspect")
268 (if nil
;; Must be reworked. Shall we offer D-Bus signatures at all?
269 (defun dbus-get-signatures (bus interface signal
)
270 "Retrieve SIGNAL's type signatures from D-Bus.
271 The result is a list of SIGNAL's type signatures. Example:
273 \(\"s\" \"b\" \"ai\"\)
275 This list represents 3 parameters of SIGNAL. The first parameter
276 is of type string, the second parameter is of type boolean, and
277 the third parameter is of type array of integer.
279 If INTERFACE or SIGNAL do not exist, or if they do not support
280 the D-Bus method org.freedesktop.DBus.Introspectable.Introspect,
281 the function returns nil."
283 (let ((introspect-xml
285 (insert (dbus-introspect bus interface
))
286 (xml-parse-region (point-min) (point-max))))
287 node interfaces signals args result
)
288 ;; Get the root node.
289 (setq node
(xml-node-name introspect-xml
))
290 ;; Get all interfaces.
291 (setq interfaces
(xml-get-children node
'interface
))
293 (when (string-equal (xml-get-attribute (car interfaces
) 'name
)
295 ;; That's the requested interface. Check for signals.
296 (setq signals
(xml-get-children (car interfaces
) 'signal
))
298 (when (string-equal (xml-get-attribute (car signals
) 'name
)
300 ;; The signal we are looking for.
301 (setq args
(xml-get-children (car signals
) 'arg
))
303 (unless (xml-get-attribute (car args
) 'type
)
304 ;; This shouldn't happen, let's escape.
305 (signal 'dbus-error
""))
306 ;; We append the signature.
308 result
(append result
309 (list (xml-get-attribute (car args
) 'type
))))
310 (setq args
(cdr args
)))
312 (setq signals
(cdr signals
)))
313 (setq interfaces nil
))
314 (setq interfaces
(cdr interfaces
)))
316 ;; We ignore `dbus-error'. There might be no introspectable interface.
322 ;; arch-tag: a47caf84-9162-4811-90cc-5d388e37b9bd
323 ;;; dbus.el ends here