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, see <http://www.gnu.org/licenses/>.
18 * Authors: Ryan Lortie <desrt@desrt.ca>
19 * Matthias Clasen <mclasen@redhat.com>
24 #include "gsettingsbackendinternal.h"
25 #include "gsimplepermission.h"
26 #include "giomodule-priv.h"
34 typedef struct _GSettingsBackendClosure GSettingsBackendClosure;
35 typedef struct _GSettingsBackendWatch GSettingsBackendWatch;
37 struct _GSettingsBackendPrivate
39 GSettingsBackendWatch *watches;
43 G_DEFINE_ABSTRACT_TYPE_WITH_PRIVATE (GSettingsBackend, g_settings_backend, G_TYPE_OBJECT)
45 /* For g_settings_backend_sync_default(), we only want to actually do
46 * the sync if the backend already exists. This avoids us creating an
47 * entire GSettingsBackend in order to call a do-nothing sync()
48 * operation on it. This variable lets us avoid that.
50 static gboolean g_settings_has_backend;
53 * SECTION:gsettingsbackend
54 * @title: GSettingsBackend
55 * @short_description: Interface for settings backend implementations
56 * @include: gio/gsettingsbackend.h
57 * @see_also: #GSettings, #GIOExtensionPoint
59 * The #GSettingsBackend interface defines a generic interface for
60 * non-strictly-typed data that is stored in a hierarchy. To implement
61 * an alternative storage backend for #GSettings, you need to implement
62 * the #GSettingsBackend interface and then make it implement the
63 * extension point #G_SETTINGS_BACKEND_EXTENSION_POINT_NAME.
65 * The interface defines methods for reading and writing values, a
66 * method for determining if writing of certain values will fail
67 * (lockdown) and a change notification mechanism.
69 * The semantics of the interface are very precisely defined and
70 * implementations must carefully adhere to the expectations of
71 * callers that are documented on each of the interface methods.
73 * Some of the GSettingsBackend functions accept or return a #GTree.
74 * These trees always have strings as keys and #GVariant as values.
75 * g_settings_backend_create_tree() is a convenience function to create
79 * The #GSettingsBackend API is exported to allow third-party
80 * implementations, but does not carry the same stability guarantees
81 * as the public GIO API. For this reason, you have to define the
82 * C preprocessor symbol #G_SETTINGS_ENABLE_BACKEND before including
83 * <filename>gio/gsettingsbackend.h</filename>
88 is_key (const gchar *key)
93 g_return_val_if_fail (key != NULL, FALSE);
94 g_return_val_if_fail (key[0] == '/', FALSE);
96 for (i = 1; key[i]; i++)
97 g_return_val_if_fail (key[i] != '/' || key[i + 1] != '/', FALSE);
101 g_return_val_if_fail (key[length - 1] != '/', FALSE);
107 is_path (const gchar *path)
112 g_return_val_if_fail (path != NULL, FALSE);
113 g_return_val_if_fail (path[0] == '/', FALSE);
115 for (i = 1; path[i]; i++)
116 g_return_val_if_fail (path[i] != '/' || path[i + 1] != '/', FALSE);
120 g_return_val_if_fail (path[length - 1] == '/', FALSE);
125 struct _GSettingsBackendWatch
128 const GSettingsListenerVTable *vtable;
129 GMainContext *context;
130 GSettingsBackendWatch *next;
133 struct _GSettingsBackendClosure
135 void (*function) (GObject *target,
136 GSettingsBackend *backend,
141 GSettingsBackend *backend;
145 GBoxedFreeFunc data1_free;
150 g_settings_backend_watch_weak_notify (gpointer data,
151 GObject *where_the_object_was)
153 GSettingsBackend *backend = data;
154 GSettingsBackendWatch **ptr;
156 /* search and remove */
157 g_mutex_lock (&backend->priv->lock);
158 for (ptr = &backend->priv->watches; *ptr; ptr = &(*ptr)->next)
159 if ((*ptr)->target == where_the_object_was)
161 GSettingsBackendWatch *tmp = *ptr;
164 g_slice_free (GSettingsBackendWatch, tmp);
166 g_mutex_unlock (&backend->priv->lock);
170 /* we didn't find it. that shouldn't happen. */
171 g_assert_not_reached ();
175 * g_settings_backend_watch:
176 * @backend: a #GSettingsBackend
177 * @target: the GObject (typically GSettings instance) to call back to
178 * @context: (allow-none): a #GMainContext, or %NULL
181 * Registers a new watch on a #GSettingsBackend.
183 * note: %NULL @context does not mean "default main context" but rather,
184 * "it is okay to dispatch in any context". If the default main context
185 * is specifically desired then it must be given.
187 * note also: if you want to get meaningful values for the @origin_tag
188 * that appears as an argument to some of the callbacks, you *must* have
189 * @context as %NULL. Otherwise, you are subject to cross-thread
190 * dispatching and whatever owned @origin_tag at the time that the event
191 * occurred may no longer own it. This is a problem if you consider that
192 * you may now be the new owner of that address and mistakenly think
193 * that the event in question originated from yourself.
195 * tl;dr: If you give a non-%NULL @context then you must ignore the
196 * value of @origin_tag given to any callbacks.
199 g_settings_backend_watch (GSettingsBackend *backend,
200 const GSettingsListenerVTable *vtable,
202 GMainContext *context)
204 GSettingsBackendWatch *watch;
206 /* For purposes of discussion, we assume that our target is a
207 * GSettings instance.
209 * Our strategy to defend against the final reference dropping on the
210 * GSettings object in a thread other than the one that is doing the
211 * dispatching is as follows:
213 * 1) hold a GObject reference on the GSettings during an outstanding
214 * dispatch. This ensures that the delivery is always possible.
216 * 2) hold a weak reference on the GSettings at other times. This
217 * allows us to receive early notification of pending destruction
218 * of the object. At this point, it is still safe to obtain a
219 * reference on the GObject to keep it alive, so #1 will work up
220 * to that point. After that point, we'll have been able to drop
221 * the watch from the list.
223 * Note, in particular, that it's not possible to simply have an
224 * "unwatch" function that gets called from the finalize function of
225 * the GSettings instance because, by that point it is no longer
226 * possible to keep the object alive using g_object_ref() and we would
227 * have no way of knowing this.
229 * Note also that we do not need to hold a reference on the main
230 * context here since the GSettings instance does that for us and we
231 * will receive the weak notify long before it is dropped. We don't
232 * even need to hold it during dispatches because our reference on the
233 * GSettings will prevent the finalize from running and dropping the
234 * ref on the context.
236 * All access to the list holds a mutex. We have some strategies to
237 * avoid some of the pain that would be associated with that.
240 watch = g_slice_new (GSettingsBackendWatch);
241 watch->context = context;
242 watch->vtable = vtable;
243 watch->target = target;
244 g_object_weak_ref (target, g_settings_backend_watch_weak_notify, backend);
246 /* linked list prepend */
247 g_mutex_lock (&backend->priv->lock);
248 watch->next = backend->priv->watches;
249 backend->priv->watches = watch;
250 g_mutex_unlock (&backend->priv->lock);
254 g_settings_backend_unwatch (GSettingsBackend *backend,
257 /* Our caller surely owns a reference on 'target', so the order of
258 * these two calls is unimportant.
260 g_object_weak_unref (target, g_settings_backend_watch_weak_notify, backend);
261 g_settings_backend_watch_weak_notify (backend, target);
265 g_settings_backend_invoke_closure (gpointer user_data)
267 GSettingsBackendClosure *closure = user_data;
269 closure->function (closure->target, closure->backend, closure->name,
270 closure->data1, closure->data2);
272 closure->data1_free (closure->data1);
273 g_object_unref (closure->backend);
274 g_object_unref (closure->target);
275 g_free (closure->name);
277 g_slice_free (GSettingsBackendClosure, closure);
283 pointer_id (gpointer a)
289 pointer_ignore (gpointer a)
294 g_settings_backend_dispatch_signal (GSettingsBackend *backend,
295 gsize function_offset,
298 GBoxedCopyFunc data1_copy,
299 GBoxedFreeFunc data1_free,
302 GSettingsBackendWatch *suffix, *watch, *next;
304 if (data1_copy == NULL)
305 data1_copy = pointer_id;
307 if (data1_free == NULL)
308 data1_free = pointer_ignore;
310 /* We're in a little bit of a tricky situation here. We need to hold
311 * a lock while traversing the list, but we don't want to hold the
312 * lock while calling back into user code.
314 * Since we're not holding the lock while we call user code, we can't
315 * render the list immutable. We can, however, store a pointer to a
316 * given suffix of the list and render that suffix immutable.
318 * Adds will never modify the suffix since adds always come in the
319 * form of prepends. We can also prevent removes from modifying the
320 * suffix since removes only happen in response to the last reference
321 * count dropping -- so just add a reference to everything in the
324 g_mutex_lock (&backend->priv->lock);
325 suffix = backend->priv->watches;
326 for (watch = suffix; watch; watch = watch->next)
327 g_object_ref (watch->target);
328 g_mutex_unlock (&backend->priv->lock);
330 /* The suffix is now immutable, so this is safe. */
331 for (watch = suffix; watch; watch = next)
333 GSettingsBackendClosure *closure;
335 closure = g_slice_new (GSettingsBackendClosure);
336 closure->backend = g_object_ref (backend);
337 closure->target = watch->target; /* we took our ref above */
338 closure->function = G_STRUCT_MEMBER (void *, watch->vtable,
340 closure->name = g_strdup (name);
341 closure->data1 = data1_copy (data1);
342 closure->data1_free = data1_free;
343 closure->data2 = data2;
345 /* we do this here because 'watch' may not live to the end of this
346 * iteration of the loop (since we may unref the target below).
351 g_main_context_invoke (watch->context,
352 g_settings_backend_invoke_closure,
355 g_settings_backend_invoke_closure (closure);
360 * g_settings_backend_changed:
361 * @backend: a #GSettingsBackend implementation
362 * @key: the name of the key
363 * @origin_tag: the origin tag
365 * Signals that a single key has possibly changed. Backend
366 * implementations should call this if a key has possibly changed its
369 * @key must be a valid key (ie starting with a slash, not containing
370 * '//', and not ending with a slash).
372 * The implementation must call this function during any call to
373 * g_settings_backend_write(), before the call returns (except in the
374 * case that no keys are actually changed and it cares to detect this
375 * fact). It may not rely on the existence of a mainloop for
376 * dispatching the signal later.
378 * The implementation may call this function at any other time it likes
379 * in response to other events (such as changes occurring outside of the
380 * program). These calls may originate from a mainloop or may originate
381 * in response to any other action (including from calls to
382 * g_settings_backend_write()).
384 * In the case that this call is in response to a call to
385 * g_settings_backend_write() then @origin_tag must be set to the same
386 * value that was passed to that call.
391 g_settings_backend_changed (GSettingsBackend *backend,
395 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend));
396 g_return_if_fail (is_key (key));
398 g_settings_backend_dispatch_signal (backend,
399 G_STRUCT_OFFSET (GSettingsListenerVTable,
401 key, origin_tag, NULL, NULL, NULL);
405 * g_settings_backend_keys_changed:
406 * @backend: a #GSettingsBackend implementation
407 * @path: the path containing the changes
408 * @items: (array zero-terminated=1): the %NULL-terminated list of changed keys
409 * @origin_tag: the origin tag
411 * Signals that a list of keys have possibly changed. Backend
412 * implementations should call this if keys have possibly changed their
415 * @path must be a valid path (ie starting and ending with a slash and
416 * not containing '//'). Each string in @items must form a valid key
417 * name when @path is prefixed to it (ie: each item must not start or
418 * end with '/' and must not contain '//').
420 * The meaning of this signal is that any of the key names resulting
421 * from the contatenation of @path with each item in @items may have
424 * The same rules for when notifications must occur apply as per
425 * g_settings_backend_changed(). These two calls can be used
426 * interchangeably if exactly one item has changed (although in that
427 * case g_settings_backend_changed() is definitely preferred).
429 * For efficiency reasons, the implementation should strive for @path to
430 * be as long as possible (ie: the longest common prefix of all of the
431 * keys that were changed) but this is not strictly required.
436 g_settings_backend_keys_changed (GSettingsBackend *backend,
438 gchar const * const *items,
441 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend));
442 g_return_if_fail (is_path (path));
444 /* XXX: should do stricter checking (ie: inspect each item) */
445 g_return_if_fail (items != NULL);
447 g_settings_backend_dispatch_signal (backend,
448 G_STRUCT_OFFSET (GSettingsListenerVTable,
450 path, (gpointer) items,
451 (GBoxedCopyFunc) g_strdupv,
452 (GBoxedFreeFunc) g_strfreev,
457 * g_settings_backend_path_changed:
458 * @backend: a #GSettingsBackend implementation
459 * @path: the path containing the changes
460 * @origin_tag: the origin tag
462 * Signals that all keys below a given path may have possibly changed.
463 * Backend implementations should call this if an entire path of keys
464 * have possibly changed their values.
466 * @path must be a valid path (ie starting and ending with a slash and
467 * not containing '//').
469 * The meaning of this signal is that any of the key which has a name
470 * starting with @path may have changed.
472 * The same rules for when notifications must occur apply as per
473 * g_settings_backend_changed(). This call might be an appropriate
474 * reasponse to a 'reset' call but implementations are also free to
475 * explicitly list the keys that were affected by that call if they can
478 * For efficiency reasons, the implementation should strive for @path to
479 * be as long as possible (ie: the longest common prefix of all of the
480 * keys that were changed) but this is not strictly required. As an
481 * example, if this function is called with the path of "/" then every
482 * single key in the application will be notified of a possible change.
487 g_settings_backend_path_changed (GSettingsBackend *backend,
491 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend));
492 g_return_if_fail (is_path (path));
494 g_settings_backend_dispatch_signal (backend,
495 G_STRUCT_OFFSET (GSettingsListenerVTable,
497 path, origin_tag, NULL, NULL, NULL);
501 * g_settings_backend_writable_changed:
502 * @backend: a #GSettingsBackend implementation
503 * @key: the name of the key
505 * Signals that the writability of a single key has possibly changed.
507 * Since GSettings performs no locking operations for itself, this call
508 * will always be made in response to external events.
513 g_settings_backend_writable_changed (GSettingsBackend *backend,
516 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend));
517 g_return_if_fail (is_key (key));
519 g_settings_backend_dispatch_signal (backend,
520 G_STRUCT_OFFSET (GSettingsListenerVTable,
522 key, NULL, NULL, NULL, NULL);
526 * g_settings_backend_path_writable_changed:
527 * @backend: a #GSettingsBackend implementation
528 * @path: the name of the path
530 * Signals that the writability of all keys below a given path may have
533 * Since GSettings performs no locking operations for itself, this call
534 * will always be made in response to external events.
539 g_settings_backend_path_writable_changed (GSettingsBackend *backend,
542 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend));
543 g_return_if_fail (is_path (path));
545 g_settings_backend_dispatch_signal (backend,
546 G_STRUCT_OFFSET (GSettingsListenerVTable,
547 path_writable_changed),
548 path, NULL, NULL, NULL, NULL);
560 g_settings_backend_flatten_one (gpointer key,
564 FlattenState *state = user_data;
565 const gchar *skey = key;
568 g_return_val_if_fail (is_key (key), TRUE);
570 /* calculate longest common prefix */
571 if (state->prefix == NULL)
575 /* first key? just take the prefix up to the last '/' */
576 state->prefix = g_strdup (skey);
577 last_byte = strrchr (state->prefix, '/') + 1;
578 state->prefix_len = last_byte - state->prefix;
583 /* find the first character that does not match. we will
584 * definitely find one because the prefix ends in '/' and the key
585 * does not. also: no two keys in the tree are the same.
587 for (i = 0; state->prefix[i] == skey[i]; i++);
589 /* check if we need to shorten the prefix */
590 if (state->prefix[i] != '\0')
592 /* find the nearest '/', terminate after it */
593 while (state->prefix[i - 1] != '/')
596 state->prefix[i] = '\0';
597 state->prefix_len = i;
602 /* save the entire item into the array.
603 * the prefixes will be removed later.
605 *state->keys++ = key;
608 *state->values++ = value;
614 * g_settings_backend_flatten_tree:
615 * @tree: a #GTree containing the changes
616 * @path: (out): the location to save the path
617 * @keys: (out) (transfer container) (array zero-terminated=1): the
618 * location to save the relative keys
619 * @values: (out) (allow-none) (transfer container) (array zero-terminated=1):
620 * the location to save the values, or %NULL
622 * Calculate the longest common prefix of all keys in a tree and write
623 * out an array of the key names relative to that prefix and,
624 * optionally, the value to store at each of those keys.
626 * You must free the value returned in @path, @keys and @values using
627 * g_free(). You should not attempt to free or unref the contents of
633 g_settings_backend_flatten_tree (GTree *tree,
638 FlattenState state = { 0, };
641 nnodes = g_tree_nnodes (tree);
643 *keys = state.keys = g_new (const gchar *, nnodes + 1);
644 state.keys[nnodes] = NULL;
648 *values = state.values = g_new (GVariant *, nnodes + 1);
649 state.values[nnodes] = NULL;
652 g_tree_foreach (tree, g_settings_backend_flatten_one, &state);
653 g_return_if_fail (*keys + nnodes == state.keys);
655 *path = state.prefix;
657 *--state.keys += state.prefix_len;
661 * g_settings_backend_changed_tree:
662 * @backend: a #GSettingsBackend implementation
663 * @tree: a #GTree containing the changes
664 * @origin_tag: the origin tag
666 * This call is a convenience wrapper. It gets the list of changes from
667 * @tree, computes the longest common prefix and calls
668 * g_settings_backend_changed().
673 g_settings_backend_changed_tree (GSettingsBackend *backend,
680 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend));
682 g_settings_backend_flatten_tree (tree, &path, &keys, NULL);
689 g_print ("changed_tree(): prefix %s\n", path);
690 for (i = 0; keys[i]; i++)
691 g_print (" %s\n", keys[i]);
696 g_settings_backend_keys_changed (backend, 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
708 * Reads a key. This call will never block.
710 * If the key exists, the value associated with it will be returned.
711 * If the key does not exist, %NULL will be returned.
713 * The returned value will be of the type given in @expected_type. If
714 * the backend stored a value of a different type then %NULL will be
717 * If @default_value is %TRUE then this gets the default value from the
718 * backend (ie: the one that the backend would contain if
719 * g_settings_reset() were called).
721 * Returns: the value that was read, or %NULL
724 g_settings_backend_read (GSettingsBackend *backend,
726 const GVariantType *expected_type,
727 gboolean default_value)
731 value = G_SETTINGS_BACKEND_GET_CLASS (backend)
732 ->read (backend, key, expected_type, default_value);
735 value = g_variant_take_ref (value);
737 if G_UNLIKELY (value && !g_variant_is_of_type (value, expected_type))
739 g_variant_unref (value);
747 * g_settings_backend_read_user_value:
748 * @backend: a #GSettingsBackend implementation
749 * @key: the key to read
750 * @expected_type: a #GVariantType
752 * Reads the 'user value' of a key.
754 * This is the value of the key that the user has control over and has
755 * set for themselves. Put another way: if the user did not set the
756 * value for themselves, then this will return %NULL (even if the
757 * sysadmin has provided a default value).
759 * Returns: the value that was read, or %NULL
762 g_settings_backend_read_user_value (GSettingsBackend *backend,
764 const GVariantType *expected_type)
768 value = G_SETTINGS_BACKEND_GET_CLASS (backend)
769 ->read_user_value (backend, key, expected_type);
772 value = g_variant_take_ref (value);
774 if G_UNLIKELY (value && !g_variant_is_of_type (value, expected_type))
776 g_variant_unref (value);
784 * g_settings_backend_write:
785 * @backend: a #GSettingsBackend implementation
786 * @key: the name of the key
787 * @value: a #GVariant value to write to this key
788 * @origin_tag: the origin tag
790 * Writes exactly one key.
792 * This call does not fail. During this call a
793 * #GSettingsBackend::changed signal will be emitted if the value of the
794 * key has changed. The updated key value will be visible to any signal
797 * One possible method that an implementation might deal with failures is
798 * to emit a second "changed" signal (either during this call, or later)
799 * to indicate that the affected keys have suddenly "changed back" to their
802 * Returns: %TRUE if the write succeeded, %FALSE if the key was not writable
805 g_settings_backend_write (GSettingsBackend *backend,
812 g_variant_ref_sink (value);
813 success = G_SETTINGS_BACKEND_GET_CLASS (backend)
814 ->write (backend, key, value, origin_tag);
815 g_variant_unref (value);
821 * g_settings_backend_write_tree:
822 * @backend: a #GSettingsBackend implementation
823 * @tree: a #GTree containing key-value pairs to write
824 * @origin_tag: the origin tag
826 * Writes one or more keys. This call will never block.
828 * The key of each item in the tree is the key name to write to and the
829 * value is a #GVariant to write. The proper type of #GTree for this
830 * call can be created with g_settings_backend_create_tree(). This call
831 * might take a reference to the tree; you must not modified the #GTree
832 * after passing it to this call.
834 * This call does not fail. During this call a #GSettingsBackend::changed
835 * signal will be emitted if any keys have been changed. The new values of
836 * all updated keys will be visible to any signal callbacks.
838 * One possible method that an implementation might deal with failures is
839 * to emit a second "changed" signal (either during this call, or later)
840 * to indicate that the affected keys have suddenly "changed back" to their
844 g_settings_backend_write_tree (GSettingsBackend *backend,
848 return G_SETTINGS_BACKEND_GET_CLASS (backend)
849 ->write_tree (backend, tree, origin_tag);
853 * g_settings_backend_reset:
854 * @backend: a #GSettingsBackend implementation
855 * @key: the name of a key
856 * @origin_tag: the origin tag
858 * "Resets" the named key to its "default" value (ie: after system-wide
859 * defaults, mandatory keys, etc. have been taken into account) or possibly
863 g_settings_backend_reset (GSettingsBackend *backend,
867 G_SETTINGS_BACKEND_GET_CLASS (backend)
868 ->reset (backend, key, origin_tag);
872 * g_settings_backend_get_writable:
873 * @backend: a #GSettingsBackend implementation
874 * @key: the name of a key
876 * Finds out if a key is available for writing to. This is the
877 * interface through which 'lockdown' is implemented. Locked down
878 * keys will have %FALSE returned by this call.
880 * You should not write to locked-down keys, but if you do, the
881 * implementation will deal with it.
883 * Returns: %TRUE if the key is writable
886 g_settings_backend_get_writable (GSettingsBackend *backend,
889 return G_SETTINGS_BACKEND_GET_CLASS (backend)
890 ->get_writable (backend, key);
894 * g_settings_backend_unsubscribe:
895 * @backend: a #GSettingsBackend
896 * @name: a key or path to subscribe to
898 * Reverses the effect of a previous call to
899 * g_settings_backend_subscribe().
902 g_settings_backend_unsubscribe (GSettingsBackend *backend,
905 G_SETTINGS_BACKEND_GET_CLASS (backend)
906 ->unsubscribe (backend, name);
910 * g_settings_backend_subscribe:
911 * @backend: a #GSettingsBackend
912 * @name: a key or path to subscribe to
914 * Requests that change signals be emitted for events on @name.
917 g_settings_backend_subscribe (GSettingsBackend *backend,
920 G_SETTINGS_BACKEND_GET_CLASS (backend)
921 ->subscribe (backend, name);
925 g_settings_backend_finalize (GObject *object)
927 GSettingsBackend *backend = G_SETTINGS_BACKEND (object);
929 g_mutex_clear (&backend->priv->lock);
931 G_OBJECT_CLASS (g_settings_backend_parent_class)
936 ignore_subscription (GSettingsBackend *backend,
942 g_settings_backend_real_read_user_value (GSettingsBackend *backend,
944 const GVariantType *expected_type)
946 return g_settings_backend_read (backend, key, expected_type, FALSE);
950 g_settings_backend_init (GSettingsBackend *backend)
952 backend->priv = g_settings_backend_get_instance_private (backend);
953 g_mutex_init (&backend->priv->lock);
957 g_settings_backend_class_init (GSettingsBackendClass *class)
959 GObjectClass *gobject_class = G_OBJECT_CLASS (class);
961 class->subscribe = ignore_subscription;
962 class->unsubscribe = ignore_subscription;
964 class->read_user_value = g_settings_backend_real_read_user_value;
966 gobject_class->finalize = g_settings_backend_finalize;
970 g_settings_backend_variant_unref0 (gpointer data)
973 g_variant_unref (data);
977 * g_settings_backend_create_tree:
979 * This is a convenience function for creating a tree that is compatible
980 * with g_settings_backend_write(). It merely calls g_tree_new_full()
981 * with strcmp(), g_free() and g_variant_unref().
983 * Returns: a new #GTree
986 g_settings_backend_create_tree (void)
988 return g_tree_new_full ((GCompareDataFunc) strcmp, NULL,
989 g_free, g_settings_backend_variant_unref0);
993 g_settings_backend_verify (gpointer impl)
995 GSettingsBackend *backend = impl;
997 if (strcmp (G_OBJECT_TYPE_NAME (backend), "GMemorySettingsBackend") == 0 &&
998 g_strcmp0 (g_getenv ("GSETTINGS_BACKEND"), "memory") != 0)
1000 g_message ("Using the 'memory' GSettings backend. Your settings "
1001 "will not be saved or shared with other applications.");
1004 g_settings_has_backend = TRUE;
1009 * g_settings_backend_get_default:
1011 * Returns the default #GSettingsBackend. It is possible to override
1012 * the default by setting the <envar>GSETTINGS_BACKEND</envar>
1013 * environment variable to the name of a settings backend.
1015 * The user gets a reference to the backend.
1017 * Returns: (transfer full): the default #GSettingsBackend
1022 g_settings_backend_get_default (void)
1024 GSettingsBackend *backend;
1026 backend = _g_io_module_get_default (G_SETTINGS_BACKEND_EXTENSION_POINT_NAME,
1027 "GSETTINGS_BACKEND",
1028 g_settings_backend_verify);
1029 return g_object_ref (backend);
1033 * g_settings_backend_get_permission:
1034 * @backend: a #GSettingsBackend
1037 * Gets the permission object associated with writing to keys below
1038 * @path on @backend.
1040 * If this is not implemented in the backend, then a %TRUE
1041 * #GSimplePermission is returned.
1043 * Returns: a non-%NULL #GPermission. Free with g_object_unref()
1046 g_settings_backend_get_permission (GSettingsBackend *backend,
1049 GSettingsBackendClass *class = G_SETTINGS_BACKEND_GET_CLASS (backend);
1051 if (class->get_permission)
1052 return class->get_permission (backend, path);
1054 return g_simple_permission_new (TRUE);
1058 * g_settings_backend_sync_default:
1060 * Syncs the default backend.
1063 g_settings_backend_sync_default (void)
1065 if (g_settings_has_backend)
1067 GSettingsBackendClass *class;
1068 GSettingsBackend *backend;
1070 backend = g_settings_backend_get_default ();
1071 class = G_SETTINGS_BACKEND_GET_CLASS (backend);
1074 class->sync (backend);