2 * Copyright © 2009, 2010 Codethink Limited
3 * Copyright © 2010 Red Hat, Inc.
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the licence, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the
17 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 * Boston, MA 02111-1307, USA.
20 * Authors: Ryan Lortie <desrt@desrt.ca>
21 * Matthias Clasen <mclasen@redhat.com>
26 #include "gsettingsbackendinternal.h"
27 #include "gsimplepermission.h"
28 #include "giomodule-priv.h"
29 #include "gio-marshal.h"
37 G_DEFINE_ABSTRACT_TYPE (GSettingsBackend
, g_settings_backend
, G_TYPE_OBJECT
)
39 typedef struct _GSettingsBackendClosure GSettingsBackendClosure
;
40 typedef struct _GSettingsBackendWatch GSettingsBackendWatch
;
42 struct _GSettingsBackendPrivate
44 GSettingsBackendWatch
*watches
;
49 * SECTION:gsettingsbackend
50 * @title: GSettingsBackend
51 * @short_description: Interface for settings backend implementations
52 * @include: gio/gsettingsbackend.h
53 * @see_also: #GSettings, #GIOExtensionPoint
55 * The #GSettingsBackend interface defines a generic interface for
56 * non-strictly-typed data that is stored in a hierarchy. To implement
57 * an alternative storage backend for #GSettings, you need to implement
58 * the #GSettingsBackend interface and then make it implement the
59 * extension point #G_SETTINGS_BACKEND_EXTENSION_POINT_NAME.
61 * The interface defines methods for reading and writing values, a
62 * method for determining if writing of certain values will fail
63 * (lockdown) and a change notification mechanism.
65 * The semantics of the interface are very precisely defined and
66 * implementations must carefully adhere to the expectations of
67 * callers that are documented on each of the interface methods.
69 * Some of the GSettingsBackend functions accept or return a #GTree.
70 * These trees always have strings as keys and #GVariant as values.
71 * g_settings_backend_create_tree() is a convenience function to create
75 * The #GSettingsBackend API is exported to allow third-party
76 * implementations, but does not carry the same stability guarantees
77 * as the public GIO API. For this reason, you have to define the
78 * C preprocessor symbol #G_SETTINGS_ENABLE_BACKEND before including
79 * <filename>gio/gsettingsbackend.h</filename>
84 is_key (const gchar
*key
)
89 g_return_val_if_fail (key
!= NULL
, FALSE
);
90 g_return_val_if_fail (key
[0] == '/', FALSE
);
92 for (i
= 1; key
[i
]; i
++)
93 g_return_val_if_fail (key
[i
] != '/' || key
[i
+ 1] != '/', FALSE
);
97 g_return_val_if_fail (key
[length
- 1] != '/', FALSE
);
103 is_path (const gchar
*path
)
108 g_return_val_if_fail (path
!= NULL
, FALSE
);
109 g_return_val_if_fail (path
[0] == '/', FALSE
);
111 for (i
= 1; path
[i
]; i
++)
112 g_return_val_if_fail (path
[i
] != '/' || path
[i
+ 1] != '/', FALSE
);
116 g_return_val_if_fail (path
[length
- 1] == '/', FALSE
);
121 struct _GSettingsBackendWatch
124 const GSettingsListenerVTable
*vtable
;
125 GMainContext
*context
;
126 GSettingsBackendWatch
*next
;
129 struct _GSettingsBackendClosure
131 void (*function
) (GObject
*target
,
132 GSettingsBackend
*backend
,
137 GSettingsBackend
*backend
;
141 GBoxedFreeFunc data1_free
;
146 g_settings_backend_watch_weak_notify (gpointer data
,
147 GObject
*where_the_object_was
)
149 GSettingsBackend
*backend
= data
;
150 GSettingsBackendWatch
**ptr
;
152 /* search and remove */
153 g_static_mutex_lock (&backend
->priv
->lock
);
154 for (ptr
= &backend
->priv
->watches
; *ptr
; ptr
= &(*ptr
)->next
)
155 if ((*ptr
)->target
== where_the_object_was
)
157 GSettingsBackendWatch
*tmp
= *ptr
;
160 g_slice_free (GSettingsBackendWatch
, tmp
);
162 g_static_mutex_unlock (&backend
->priv
->lock
);
166 /* we didn't find it. that shouldn't happen. */
167 g_assert_not_reached ();
171 * g_settings_backend_watch:
172 * @backend: a #GSettingsBackend
173 * @target: the GObject (typically GSettings instance) to call back to
174 * @context: a #GMainContext, or %NULL
177 * Registers a new watch on a #GSettingsBackend.
179 * note: %NULL @context does not mean "default main context" but rather,
180 * "it is okay to dispatch in any context". If the default main context
181 * is specifically desired then it must be given.
183 * note also: if you want to get meaningful values for the @origin_tag
184 * that appears as an argument to some of the callbacks, you *must* have
185 * @context as %NULL. Otherwise, you are subject to cross-thread
186 * dispatching and whatever owned @origin_tag at the time that the event
187 * occured may no longer own it. This is a problem if you consider that
188 * you may now be the new owner of that address and mistakenly think
189 * that the event in question originated from yourself.
191 * tl;dr: If you give a non-%NULL @context then you must ignore the
192 * value of @origin_tag given to any callbacks.
195 g_settings_backend_watch (GSettingsBackend
*backend
,
196 const GSettingsListenerVTable
*vtable
,
198 GMainContext
*context
)
200 GSettingsBackendWatch
*watch
;
202 /* For purposes of discussion, we assume that our target is a
203 * GSettings instance.
205 * Our strategy to defend against the final reference dropping on the
206 * GSettings object in a thread other than the one that is doing the
207 * dispatching is as follows:
209 * 1) hold a GObject reference on the GSettings during an outstanding
210 * dispatch. This ensures that the delivery is always possible.
212 * 2) hold a weak reference on the GSettings at other times. This
213 * allows us to receive early notification of pending destruction
214 * of the object. At this point, it is still safe to obtain a
215 * reference on the GObject to keep it alive, so #1 will work up
216 * to that point. After that point, we'll have been able to drop
217 * the watch from the list.
219 * Note, in particular, that it's not possible to simply have an
220 * "unwatch" function that gets called from the finalize function of
221 * the GSettings instance because, by that point it is no longer
222 * possible to keep the object alive using g_object_ref() and we would
223 * have no way of knowing this.
225 * Note also that we do not need to hold a reference on the main
226 * context here since the GSettings instance does that for us and we
227 * will receive the weak notify long before it is dropped. We don't
228 * even need to hold it during dispatches because our reference on the
229 * GSettings will prevent the finalize from running and dropping the
230 * ref on the context.
232 * All access to the list holds a mutex. We have some strategies to
233 * avoid some of the pain that would be associated with that.
236 watch
= g_slice_new (GSettingsBackendWatch
);
237 watch
->context
= context
;
238 watch
->vtable
= vtable
;
239 watch
->target
= target
;
240 g_object_weak_ref (target
, g_settings_backend_watch_weak_notify
, backend
);
242 /* linked list prepend */
243 g_static_mutex_lock (&backend
->priv
->lock
);
244 watch
->next
= backend
->priv
->watches
;
245 backend
->priv
->watches
= watch
;
246 g_static_mutex_unlock (&backend
->priv
->lock
);
250 g_settings_backend_unwatch (GSettingsBackend
*backend
,
253 /* Our caller surely owns a reference on 'target', so the order of
254 * these two calls is unimportant.
256 g_object_weak_unref (target
, g_settings_backend_watch_weak_notify
, backend
);
257 g_settings_backend_watch_weak_notify (backend
, target
);
261 g_settings_backend_invoke_closure (gpointer user_data
)
263 GSettingsBackendClosure
*closure
= user_data
;
265 closure
->function (closure
->target
, closure
->backend
, closure
->name
,
266 closure
->data1
, closure
->data2
);
268 closure
->data1_free (closure
->data1
);
269 g_object_unref (closure
->backend
);
270 g_object_unref (closure
->target
);
271 g_free (closure
->name
);
273 g_slice_free (GSettingsBackendClosure
, closure
);
279 pointer_id (gpointer a
)
285 pointer_ignore (gpointer a
)
290 g_settings_backend_dispatch_signal (GSettingsBackend
*backend
,
291 gsize function_offset
,
294 GBoxedCopyFunc data1_copy
,
295 GBoxedFreeFunc data1_free
,
298 GSettingsBackendWatch
*suffix
, *watch
, *next
;
300 if (data1_copy
== NULL
)
301 data1_copy
= pointer_id
;
303 if (data1_free
== NULL
)
304 data1_free
= pointer_ignore
;
306 /* We're in a little bit of a tricky situation here. We need to hold
307 * a lock while traversing the list, but we don't want to hold the
308 * lock while calling back into user code.
310 * Since we're not holding the lock while we call user code, we can't
311 * render the list immutable. We can, however, store a pointer to a
312 * given suffix of the list and render that suffix immutable.
314 * Adds will never modify the suffix since adds always come in the
315 * form of prepends. We can also prevent removes from modifying the
316 * suffix since removes only happen in response to the last reference
317 * count dropping -- so just add a reference to everything in the
320 g_static_mutex_lock (&backend
->priv
->lock
);
321 suffix
= backend
->priv
->watches
;
322 for (watch
= suffix
; watch
; watch
= watch
->next
)
323 g_object_ref (watch
->target
);
324 g_static_mutex_unlock (&backend
->priv
->lock
);
326 /* The suffix is now immutable, so this is safe. */
327 for (watch
= suffix
; watch
; watch
= next
)
329 GSettingsBackendClosure
*closure
;
331 closure
= g_slice_new (GSettingsBackendClosure
);
332 closure
->backend
= g_object_ref (backend
);
333 closure
->target
= watch
->target
; /* we took our ref above */
334 closure
->function
= G_STRUCT_MEMBER (void *, watch
->vtable
,
336 closure
->name
= g_strdup (name
);
337 closure
->data1
= data1_copy (data1
);
338 closure
->data1_free
= data1_free
;
339 closure
->data2
= data2
;
341 /* we do this here because 'watch' may not live to the end of this
342 * iteration of the loop (since we may unref the target below).
347 g_main_context_invoke (watch
->context
,
348 g_settings_backend_invoke_closure
,
351 g_settings_backend_invoke_closure (closure
);
356 * g_settings_backend_changed:
357 * @backend: a #GSettingsBackend implementation
358 * @key: the name of the key
359 * @origin_tag: the origin tag
361 * Signals that a single key has possibly changed. Backend
362 * implementations should call this if a key has possibly changed its
365 * @key must be a valid key (ie starting with a slash, not containing
366 * '//', and not ending with a slash).
368 * The implementation must call this function during any call to
369 * g_settings_backend_write(), before the call returns (except in the
370 * case that no keys are actually changed and it cares to detect this
371 * fact). It may not rely on the existence of a mainloop for
372 * dispatching the signal later.
374 * The implementation may call this function at any other time it likes
375 * in response to other events (such as changes occuring outside of the
376 * program). These calls may originate from a mainloop or may originate
377 * in response to any other action (including from calls to
378 * g_settings_backend_write()).
380 * In the case that this call is in response to a call to
381 * g_settings_backend_write() then @origin_tag must be set to the same
382 * value that was passed to that call.
387 g_settings_backend_changed (GSettingsBackend
*backend
,
391 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend
));
392 g_return_if_fail (is_key (key
));
394 g_settings_backend_dispatch_signal (backend
,
395 G_STRUCT_OFFSET (GSettingsListenerVTable
,
397 key
, origin_tag
, NULL
, NULL
, NULL
);
401 * g_settings_backend_keys_changed:
402 * @backend: a #GSettingsBackend implementation
403 * @path: the path containing the changes
404 * @items: (array zero-terminated=1): the %NULL-terminated list of changed keys
405 * @origin_tag: the origin tag
407 * Signals that a list of keys have possibly changed. Backend
408 * implementations should call this if keys have possibly changed their
411 * @path must be a valid path (ie starting and ending with a slash and
412 * not containing '//'). Each string in @items must form a valid key
413 * name when @path is prefixed to it (ie: each item must not start or
414 * end with '/' and must not contain '//').
416 * The meaning of this signal is that any of the key names resulting
417 * from the contatenation of @path with each item in @items may have
420 * The same rules for when notifications must occur apply as per
421 * g_settings_backend_changed(). These two calls can be used
422 * interchangeably if exactly one item has changed (although in that
423 * case g_settings_backend_changed() is definitely preferred).
425 * For efficiency reasons, the implementation should strive for @path to
426 * be as long as possible (ie: the longest common prefix of all of the
427 * keys that were changed) but this is not strictly required.
432 g_settings_backend_keys_changed (GSettingsBackend
*backend
,
434 gchar
const * const *items
,
437 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend
));
438 g_return_if_fail (is_path (path
));
440 /* XXX: should do stricter checking (ie: inspect each item) */
441 g_return_if_fail (items
!= NULL
);
443 g_settings_backend_dispatch_signal (backend
,
444 G_STRUCT_OFFSET (GSettingsListenerVTable
,
446 path
, (gpointer
) items
,
447 (GBoxedCopyFunc
) g_strdupv
,
448 (GBoxedFreeFunc
) g_strfreev
,
453 * g_settings_backend_path_changed:
454 * @backend: a #GSettingsBackend implementation
455 * @path: the path containing the changes
456 * @origin_tag: the origin tag
458 * Signals that all keys below a given path may have possibly changed.
459 * Backend implementations should call this if an entire path of keys
460 * have possibly changed their values.
462 * @path must be a valid path (ie starting and ending with a slash and
463 * not containing '//').
465 * The meaning of this signal is that any of the key which has a name
466 * starting with @path may have changed.
468 * The same rules for when notifications must occur apply as per
469 * g_settings_backend_changed(). This call might be an appropriate
470 * reasponse to a 'reset' call but implementations are also free to
471 * explicitly list the keys that were affected by that call if they can
474 * For efficiency reasons, the implementation should strive for @path to
475 * be as long as possible (ie: the longest common prefix of all of the
476 * keys that were changed) but this is not strictly required. As an
477 * example, if this function is called with the path of "/" then every
478 * single key in the application will be notified of a possible change.
483 g_settings_backend_path_changed (GSettingsBackend
*backend
,
487 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend
));
488 g_return_if_fail (is_path (path
));
490 g_settings_backend_dispatch_signal (backend
,
491 G_STRUCT_OFFSET (GSettingsListenerVTable
,
493 path
, origin_tag
, NULL
, NULL
, NULL
);
497 * g_settings_backend_writable_changed:
498 * @backend: a #GSettingsBackend implementation
499 * @key: the name of the key
501 * Signals that the writability of a single key has possibly changed.
503 * Since GSettings performs no locking operations for itself, this call
504 * will always be made in response to external events.
509 g_settings_backend_writable_changed (GSettingsBackend
*backend
,
512 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend
));
513 g_return_if_fail (is_key (key
));
515 g_settings_backend_dispatch_signal (backend
,
516 G_STRUCT_OFFSET (GSettingsListenerVTable
,
518 key
, NULL
, NULL
, NULL
, NULL
);
522 * g_settings_backend_path_writable_changed:
523 * @backend: a #GSettingsBackend implementation
524 * @path: the name of the path
526 * Signals that the writability of all keys below a given path may have
529 * Since GSettings performs no locking operations for itself, this call
530 * will always be made in response to external events.
535 g_settings_backend_path_writable_changed (GSettingsBackend
*backend
,
538 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend
));
539 g_return_if_fail (is_path (path
));
541 g_settings_backend_dispatch_signal (backend
,
542 G_STRUCT_OFFSET (GSettingsListenerVTable
,
543 path_writable_changed
),
544 path
, NULL
, NULL
, NULL
, NULL
);
556 g_settings_backend_flatten_one (gpointer key
,
560 FlattenState
*state
= user_data
;
561 const gchar
*skey
= key
;
564 g_return_val_if_fail (is_key (key
), TRUE
);
566 /* calculate longest common prefix */
567 if (state
->prefix
== NULL
)
571 /* first key? just take the prefix up to the last '/' */
572 state
->prefix
= g_strdup (skey
);
573 last_byte
= strrchr (state
->prefix
, '/') + 1;
574 state
->prefix_len
= last_byte
- state
->prefix
;
579 /* find the first character that does not match. we will
580 * definitely find one because the prefix ends in '/' and the key
581 * does not. also: no two keys in the tree are the same.
583 for (i
= 0; state
->prefix
[i
] == skey
[i
]; i
++);
585 /* check if we need to shorten the prefix */
586 if (state
->prefix
[i
] != '\0')
588 /* find the nearest '/', terminate after it */
589 while (state
->prefix
[i
- 1] != '/')
592 state
->prefix
[i
] = '\0';
593 state
->prefix_len
= i
;
598 /* save the entire item into the array.
599 * the prefixes will be removed later.
601 *state
->keys
++ = key
;
604 *state
->values
++ = value
;
610 * g_settings_backend_flatten_tree:
611 * @tree: a #GTree containing the changes
612 * @path: (out): the location to save the path
613 * @keys: (out) (transfer container) (array zero-terminated=1): the
614 * location to save the relative keys
615 * @values: (out) (allow-none) (transfer container) (array zero-terminated=1):
616 * the location to save the values, or %NULL
618 * Calculate the longest common prefix of all keys in a tree and write
619 * out an array of the key names relative to that prefix and,
620 * optionally, the value to store at each of those keys.
622 * You must free the value returned in @path, @keys and @values using
623 * g_free(). You should not attempt to free or unref the contents of
629 g_settings_backend_flatten_tree (GTree
*tree
,
634 FlattenState state
= { 0, };
637 nnodes
= g_tree_nnodes (tree
);
639 *keys
= state
.keys
= g_new (const gchar
*, nnodes
+ 1);
640 state
.keys
[nnodes
] = NULL
;
644 *values
= state
.values
= g_new (GVariant
*, nnodes
+ 1);
645 state
.values
[nnodes
] = NULL
;
648 g_tree_foreach (tree
, g_settings_backend_flatten_one
, &state
);
649 g_return_if_fail (*keys
+ nnodes
== state
.keys
);
651 *path
= state
.prefix
;
653 *--state
.keys
+= state
.prefix_len
;
657 * g_settings_backend_changed_tree:
658 * @backend: a #GSettingsBackend implementation
659 * @tree: a #GTree containing the changes
660 * @origin_tag: the origin tag
662 * This call is a convenience wrapper. It gets the list of changes from
663 * @tree, computes the longest common prefix and calls
664 * g_settings_backend_changed().
669 g_settings_backend_changed_tree (GSettingsBackend
*backend
,
673 GSettingsBackendWatch
*watch
;
677 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend
));
679 g_settings_backend_flatten_tree (tree
, &path
, &keys
, NULL
);
686 g_print ("changed_tree(): prefix %s\n", path
);
687 for (i
= 0; keys
[i
]; i
++)
688 g_print (" %s\n", keys
[i
]);
693 for (watch
= backend
->priv
->watches
; watch
; watch
= watch
->next
)
694 watch
->vtable
->keys_changed (watch
->target
, backend
,
695 path
, keys
, origin_tag
);
702 * g_settings_backend_read:
703 * @backend: a #GSettingsBackend implementation
704 * @key: the key to read
705 * @expected_type: a #GVariantType
706 * @default_value: if the default value should be returned
707 * @returns: the value that was read, or %NULL
709 * Reads a key. This call will never block.
711 * If the key exists, the value associated with it will be returned.
712 * If the key does not exist, %NULL will be returned.
714 * The returned value will be of the type given in @expected_type. If
715 * the backend stored a value of a different type then %NULL will be
718 * If @default_value is %TRUE then this gets the default value from the
719 * backend (ie: the one that the backend would contain if
720 * g_settings_reset() were called).
723 g_settings_backend_read (GSettingsBackend
*backend
,
725 const GVariantType
*expected_type
,
726 gboolean default_value
)
730 value
= G_SETTINGS_BACKEND_GET_CLASS (backend
)
731 ->read (backend
, key
, expected_type
, default_value
);
733 if G_UNLIKELY (value
&& !g_variant_is_of_type (value
, expected_type
))
735 g_variant_unref (value
);
743 * g_settings_backend_write:
744 * @backend: a #GSettingsBackend implementation
745 * @key: the name of the key
746 * @value: a #GVariant value to write to this key
747 * @origin_tag: the origin tag
748 * @returns: %TRUE if the write succeeded, %FALSE if the key was not writable
750 * Writes exactly one key.
752 * This call does not fail. During this call a
753 * #GSettingsBackend::changed signal will be emitted if the value of the
754 * key has changed. The updated key value will be visible to any signal
757 * One possible method that an implementation might deal with failures is
758 * to emit a second "changed" signal (either during this call, or later)
759 * to indicate that the affected keys have suddenly "changed back" to their
763 g_settings_backend_write (GSettingsBackend
*backend
,
768 return G_SETTINGS_BACKEND_GET_CLASS (backend
)
769 ->write (backend
, key
, value
, origin_tag
);
773 * g_settings_backend_write_keys:
774 * @backend: a #GSettingsBackend implementation
775 * @values: a #GTree containing key-value pairs to write
776 * @origin_tag: the origin tag
778 * Writes one or more keys. This call will never block.
780 * The key of each item in the tree is the key name to write to and the
781 * value is a #GVariant to write. The proper type of #GTree for this
782 * call can be created with g_settings_backend_create_tree(). This call
783 * might take a reference to the tree; you must not modified the #GTree
784 * after passing it to this call.
786 * This call does not fail. During this call a #GSettingsBackend::changed
787 * signal will be emitted if any keys have been changed. The new values of
788 * all updated keys will be visible to any signal callbacks.
790 * One possible method that an implementation might deal with failures is
791 * to emit a second "changed" signal (either during this call, or later)
792 * to indicate that the affected keys have suddenly "changed back" to their
796 g_settings_backend_write_tree (GSettingsBackend
*backend
,
800 return G_SETTINGS_BACKEND_GET_CLASS (backend
)
801 ->write_tree (backend
, tree
, origin_tag
);
805 * g_settings_backend_reset:
806 * @backend: a #GSettingsBackend implementation
807 * @key: the name of a key
808 * @origin_tag: the origin tag
810 * "Resets" the named key to its "default" value (ie: after system-wide
811 * defaults, mandatory keys, etc. have been taken into account) or possibly
815 g_settings_backend_reset (GSettingsBackend
*backend
,
819 G_SETTINGS_BACKEND_GET_CLASS (backend
)
820 ->reset (backend
, key
, origin_tag
);
824 * g_settings_backend_get_writable:
825 * @backend: a #GSettingsBackend implementation
826 * @key: the name of a key
827 * @returns: %TRUE if the key is writable
829 * Finds out if a key is available for writing to. This is the
830 * interface through which 'lockdown' is implemented. Locked down
831 * keys will have %FALSE returned by this call.
833 * You should not write to locked-down keys, but if you do, the
834 * implementation will deal with it.
837 g_settings_backend_get_writable (GSettingsBackend
*backend
,
840 return G_SETTINGS_BACKEND_GET_CLASS (backend
)
841 ->get_writable (backend
, key
);
845 * g_settings_backend_unsubscribe:
846 * @backend: a #GSettingsBackend
847 * @name: a key or path to subscribe to
849 * Reverses the effect of a previous call to
850 * g_settings_backend_subscribe().
853 g_settings_backend_unsubscribe (GSettingsBackend
*backend
,
856 G_SETTINGS_BACKEND_GET_CLASS (backend
)
857 ->unsubscribe (backend
, name
);
861 * g_settings_backend_subscribe:
862 * @backend: a #GSettingsBackend
863 * @name: a key or path to subscribe to
865 * Requests that change signals be emitted for events on @name.
868 g_settings_backend_subscribe (GSettingsBackend
*backend
,
871 G_SETTINGS_BACKEND_GET_CLASS (backend
)
872 ->subscribe (backend
, name
);
876 g_settings_backend_finalize (GObject
*object
)
878 GSettingsBackend
*backend
= G_SETTINGS_BACKEND (object
);
880 g_static_mutex_unlock (&backend
->priv
->lock
);
882 G_OBJECT_CLASS (g_settings_backend_parent_class
)
887 ignore_subscription (GSettingsBackend
*backend
,
893 g_settings_backend_init (GSettingsBackend
*backend
)
895 backend
->priv
= G_TYPE_INSTANCE_GET_PRIVATE (backend
,
896 G_TYPE_SETTINGS_BACKEND
,
897 GSettingsBackendPrivate
);
898 g_static_mutex_init (&backend
->priv
->lock
);
902 g_settings_backend_class_init (GSettingsBackendClass
*class)
904 GObjectClass
*gobject_class
= G_OBJECT_CLASS (class);
906 class->subscribe
= ignore_subscription
;
907 class->unsubscribe
= ignore_subscription
;
909 gobject_class
->finalize
= g_settings_backend_finalize
;
911 g_type_class_add_private (class, sizeof (GSettingsBackendPrivate
));
915 * g_settings_backend_create_tree:
916 * @returns: a new #GTree
918 * This is a convenience function for creating a tree that is compatible
919 * with g_settings_backend_write(). It merely calls g_tree_new_full()
920 * with strcmp(), g_free() and g_variant_unref().
923 g_settings_backend_create_tree (void)
925 return g_tree_new_full ((GCompareDataFunc
) strcmp
, NULL
,
926 g_free
, (GDestroyNotify
) g_variant_unref
);
930 * g_settings_backend_get_default:
931 * @returns: (transfer full): the default #GSettingsBackend
933 * Returns the default #GSettingsBackend. It is possible to override
934 * the default by setting the <envar>GSETTINGS_BACKEND</envar>
935 * environment variable to the name of a settings backend.
937 * The user gets a reference to the backend.
942 g_settings_backend_get_default (void)
944 static gsize backend
;
946 if (g_once_init_enter (&backend
))
948 GSettingsBackend
*instance
;
949 GIOExtensionPoint
*point
;
950 GIOExtension
*extension
;
951 GType extension_type
;
955 _g_io_modules_ensure_loaded ();
957 point
= g_io_extension_point_lookup (G_SETTINGS_BACKEND_EXTENSION_POINT_NAME
);
960 if ((env
= getenv ("GSETTINGS_BACKEND")))
962 extension
= g_io_extension_point_get_extension_by_name (point
, env
);
964 if (extension
== NULL
)
965 g_warning ("Can't find GSettings backend '%s' given in "
966 "GSETTINGS_BACKEND environment variable", env
);
969 if (extension
== NULL
)
971 extensions
= g_io_extension_point_get_extensions (point
);
973 if (extensions
== NULL
)
974 g_error ("No GSettingsBackend implementations exist.");
976 extension
= extensions
->data
;
978 if (strcmp (g_io_extension_get_name (extension
), "memory") == 0)
979 g_message ("Using the 'memory' GSettings backend. Your settings "
980 "will not be saved or shared with other applications.");
983 extension_type
= g_io_extension_get_type (extension
);
984 instance
= g_object_new (extension_type
, NULL
);
986 g_once_init_leave (&backend
, (gsize
) instance
);
989 return g_object_ref ((void *) backend
);
993 * g_settings_backend_get_permission:
994 * @backend: a #GSettingsBackend
996 * @returns: a non-%NULL #GPermission. Free with g_object_unref()
998 * Gets the permission object associated with writing to keys below
1001 * If this is not implemented in the backend, then a %TRUE
1002 * #GSimplePermission is returned.
1005 g_settings_backend_get_permission (GSettingsBackend
*backend
,
1008 GSettingsBackendClass
*class = G_SETTINGS_BACKEND_GET_CLASS (backend
);
1010 if (class->get_permission
)
1011 return class->get_permission (backend
, path
);
1013 return g_simple_permission_new (TRUE
);
1017 * g_settings_backend_sync_default:
1019 * Syncs the default backend.
1022 g_settings_backend_sync_default (void)
1024 GSettingsBackendClass
*class;
1025 GSettingsBackend
*backend
;
1027 backend
= g_settings_backend_get_default ();
1028 class = G_SETTINGS_BACKEND_GET_CLASS (backend
);
1031 class->sync (backend
);