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 "gnullsettingsbackend.h"
28 #include "gsimplepermission.h"
29 #include "giomodule-priv.h"
30 #include "gio-marshal.h"
38 G_DEFINE_ABSTRACT_TYPE (GSettingsBackend
, g_settings_backend
, G_TYPE_OBJECT
)
40 typedef struct _GSettingsBackendClosure GSettingsBackendClosure
;
41 typedef struct _GSettingsBackendWatch GSettingsBackendWatch
;
43 struct _GSettingsBackendPrivate
45 GSettingsBackendWatch
*watches
;
50 * SECTION:gsettingsbackend
51 * @title: GSettingsBackend
52 * @short_description: an interface for settings backend implementations
53 * @include: gio/gsettingsbackend.h
54 * @see_also: #GSettings, #GIOExtensionPoint
56 * The #GSettingsBackend interface defines a generic interface for
57 * non-strictly-typed data that is stored in a hierarchy. To implement
58 * an alternative storage backend for #GSettings, you need to implement
59 * the #GSettingsBackend interface and then make it implement the
60 * extension point #G_SETTINGS_BACKEND_EXTENSION_POINT_NAME.
62 * The interface defines methods for reading and writing values, a
63 * method for determining if writing of certain values will fail
64 * (lockdown) and a change notification mechanism.
66 * The semantics of the interface are very precisely defined and
67 * implementations must carefully adhere to the expectations of
68 * callers that are documented on each of the interface methods.
70 * Some of the GSettingsBackend functions accept or return a #GTree.
71 * These trees always have strings as keys and #GVariant as values.
72 * g_settings_backend_create_tree() is a convenience function to create
76 * The #GSettingsBackend API is exported to allow third-party
77 * implementations, but does not carry the same stability guarantees
78 * as the public GIO API. For this reason, you have to define the
79 * C preprocessor symbol #G_SETTINGS_ENABLE_BACKEND before including
80 * <filename>gio/gsettingsbackend.h</filename>
85 is_key (const gchar
*key
)
90 g_return_val_if_fail (key
!= NULL
, FALSE
);
91 g_return_val_if_fail (key
[0] == '/', FALSE
);
93 for (i
= 1; key
[i
]; i
++)
94 g_return_val_if_fail (key
[i
] != '/' || key
[i
+ 1] != '/', FALSE
);
98 g_return_val_if_fail (key
[length
- 1] != '/', FALSE
);
104 is_path (const gchar
*path
)
109 g_return_val_if_fail (path
!= NULL
, FALSE
);
110 g_return_val_if_fail (path
[0] == '/', FALSE
);
112 for (i
= 1; path
[i
]; i
++)
113 g_return_val_if_fail (path
[i
] != '/' || path
[i
+ 1] != '/', FALSE
);
117 g_return_val_if_fail (path
[length
- 1] == '/', FALSE
);
123 g_settings_backend_get_active_context (void)
125 GMainContext
*context
;
128 if ((source
= g_main_current_source ()))
129 context
= g_source_get_context (source
);
133 context
= g_main_context_get_thread_default ();
136 context
= g_main_context_default ();
142 struct _GSettingsBackendWatch
145 GMainContext
*context
;
146 GSettingsBackendChangedFunc changed
;
147 GSettingsBackendPathChangedFunc path_changed
;
148 GSettingsBackendKeysChangedFunc keys_changed
;
149 GSettingsBackendWritableChangedFunc writable_changed
;
150 GSettingsBackendPathWritableChangedFunc path_writable_changed
;
152 GSettingsBackendWatch
*next
;
155 struct _GSettingsBackendClosure
157 void (*function
) (GSettingsBackend
*backend
,
163 GSettingsBackend
*backend
;
167 GBoxedFreeFunc data1_free
;
172 g_settings_backend_watch_weak_notify (gpointer data
,
173 GObject
*where_the_object_was
)
175 GSettingsBackend
*backend
= data
;
176 GSettingsBackendWatch
**ptr
;
178 /* search and remove */
179 g_static_mutex_lock (&backend
->priv
->lock
);
180 for (ptr
= &backend
->priv
->watches
; *ptr
; ptr
= &(*ptr
)->next
)
181 if ((*ptr
)->target
== where_the_object_was
)
183 GSettingsBackendWatch
*tmp
= *ptr
;
186 g_slice_free (GSettingsBackendWatch
, tmp
);
188 g_static_mutex_unlock (&backend
->priv
->lock
);
192 /* we didn't find it. that shouldn't happen. */
193 g_assert_not_reached ();
197 * g_settings_backend_watch:
198 * @backend: a #GSettingsBackend
199 * @target: the GObject (typically GSettings instance) to call back to
200 * @context: a #GMainContext, or %NULL
203 * Registers a new watch on a #GSettingsBackend.
205 * note: %NULL @context does not mean "default main context" but rather,
206 * "it is okay to dispatch in any context". If the default main context
207 * is specifically desired then it must be given.
209 * note also: if you want to get meaningful values for the @origin_tag
210 * that appears as an argument to some of the callbacks, you *must* have
211 * @context as %NULL. Otherwise, you are subject to cross-thread
212 * dispatching and whatever owned @origin_tag at the time that the event
213 * occured may no longer own it. This is a problem if you consider that
214 * you may now be the new owner of that address and mistakenly think
215 * that the event in question originated from yourself.
217 * tl;dr: If you give a non-%NULL @context then you must ignore the
218 * value of @origin_tag given to any callbacks.
221 g_settings_backend_watch (GSettingsBackend
*backend
,
223 GMainContext
*context
,
224 GSettingsBackendChangedFunc changed
,
225 GSettingsBackendPathChangedFunc path_changed
,
226 GSettingsBackendKeysChangedFunc keys_changed
,
227 GSettingsBackendWritableChangedFunc writable_changed
,
228 GSettingsBackendPathWritableChangedFunc path_writable_changed
)
230 GSettingsBackendWatch
*watch
;
232 /* For purposes of discussion, we assume that our target is a
233 * GSettings instance.
235 * Our strategy to defend against the final reference dropping on the
236 * GSettings object in a thread other than the one that is doing the
237 * dispatching is as follows:
239 * 1) hold a GObject reference on the GSettings during an outstanding
240 * dispatch. This ensures that the delivery is always possible.
242 * 2) hold a weak reference on the GSettings at other times. This
243 * allows us to receive early notification of pending destruction
244 * of the object. At this point, it is still safe to obtain a
245 * reference on the GObject to keep it alive, so #1 will work up
246 * to that point. After that point, we'll have been able to drop
247 * the watch from the list.
249 * Note, in particular, that it's not possible to simply have an
250 * "unwatch" function that gets called from the finalize function of
251 * the GSettings instance because, by that point it is no longer
252 * possible to keep the object alive using g_object_ref() and we would
253 * have no way of knowing this.
255 * Note also that we do not need to hold a reference on the main
256 * context here since the GSettings instance does that for us and we
257 * will receive the weak notify long before it is dropped. We don't
258 * even need to hold it during dispatches because our reference on the
259 * GSettings will prevent the finalize from running and dropping the
260 * ref on the context.
262 * All access to the list holds a mutex. We have some strategies to
263 * avoid some of the pain that would be associated with that.
266 watch
= g_slice_new (GSettingsBackendWatch
);
267 watch
->context
= context
;
268 watch
->target
= target
;
269 g_object_weak_ref (target
, g_settings_backend_watch_weak_notify
, backend
);
271 watch
->changed
= changed
;
272 watch
->path_changed
= path_changed
;
273 watch
->keys_changed
= keys_changed
;
274 watch
->writable_changed
= writable_changed
;
275 watch
->path_writable_changed
= path_writable_changed
;
277 /* linked list prepend */
278 g_static_mutex_lock (&backend
->priv
->lock
);
279 watch
->next
= backend
->priv
->watches
;
280 backend
->priv
->watches
= watch
;
281 g_static_mutex_unlock (&backend
->priv
->lock
);
285 g_settings_backend_unwatch (GSettingsBackend
*backend
,
288 /* Our caller surely owns a reference on 'target', so the order of
289 * these two calls is unimportant.
291 g_object_weak_unref (target
, g_settings_backend_watch_weak_notify
, backend
);
292 g_settings_backend_watch_weak_notify (backend
, target
);
296 g_settings_backend_invoke_closure (gpointer user_data
)
298 GSettingsBackendClosure
*closure
= user_data
;
300 closure
->function (closure
->backend
, closure
->target
, closure
->name
,
301 closure
->data1
, closure
->data2
);
303 closure
->data1_free (closure
->data1
);
304 g_object_unref (closure
->backend
);
305 g_object_unref (closure
->target
);
306 g_free (closure
->name
);
308 g_slice_free (GSettingsBackendClosure
, closure
);
314 pointer_id (gpointer a
)
320 pointer_ignore (gpointer a
)
325 g_settings_backend_dispatch_signal (GSettingsBackend
*backend
,
326 gsize function_offset
,
329 GBoxedCopyFunc data1_copy
,
330 GBoxedFreeFunc data1_free
,
333 GMainContext
*context
, *here_and_now
;
334 GSettingsBackendWatch
*watch
;
336 /* We need to hold the mutex here (to prevent a node from being
337 * deleted as we are traversing the list). Since we should not
338 * re-enter user code while holding this mutex, we create a
339 * one-time-use GMainContext and populate it with the events that we
340 * would have called directly. We dispatch these events after
341 * releasing the lock. Note that the GObject reference is acquired on
342 * the target while holding the mutex and the mutex needs to be held
343 * as part of the destruction of any GSettings instance (via the weak
344 * reference handling). This is the key to the safety of the whole
348 if (data1_copy
== NULL
)
349 data1_copy
= pointer_id
;
351 if (data1_free
== NULL
)
352 data1_free
= pointer_ignore
;
354 context
= g_settings_backend_get_active_context ();
355 here_and_now
= g_main_context_new ();
357 /* traverse the (immutable while holding lock) list */
358 g_static_mutex_lock (&backend
->priv
->lock
);
359 for (watch
= backend
->priv
->watches
; watch
; watch
= watch
->next
)
361 GSettingsBackendClosure
*closure
;
364 closure
= g_slice_new (GSettingsBackendClosure
);
365 closure
->backend
= g_object_ref (backend
);
366 closure
->target
= g_object_ref (watch
->target
);
367 closure
->function
= G_STRUCT_MEMBER (void *, watch
, function_offset
);
368 closure
->name
= g_strdup (name
);
369 closure
->data1
= data1_copy (data1
);
370 closure
->data1_free
= data1_free
;
371 closure
->data2
= data2
;
373 source
= g_idle_source_new ();
374 g_source_set_priority (source
, G_PRIORITY_DEFAULT
);
375 g_source_set_callback (source
,
376 g_settings_backend_invoke_closure
,
379 if (watch
->context
&& watch
->context
!= context
)
380 g_source_attach (source
, watch
->context
);
382 g_source_attach (source
, here_and_now
);
384 g_source_unref (source
);
386 g_static_mutex_unlock (&backend
->priv
->lock
);
388 while (g_main_context_iteration (here_and_now
, FALSE
));
389 g_main_context_unref (here_and_now
);
393 * g_settings_backend_changed:
394 * @backend: a #GSettingsBackend implementation
395 * @key: the name of the key
396 * @origin_tag: the origin tag
398 * Signals that a single key has possibly changed. Backend
399 * implementations should call this if a key has possibly changed its
402 * @key must be a valid key (ie: starting with a slash, not containing
403 * '//', and not ending with a slash).
405 * The implementation must call this function during any call to
406 * g_settings_backend_write(), before the call returns (except in the
407 * case that no keys are actually changed and it cares to detect this
408 * fact). It may not rely on the existence of a mainloop for
409 * dispatching the signal later.
411 * The implementation may call this function at any other time it likes
412 * in response to other events (such as changes occuring outside of the
413 * program). These calls may originate from a mainloop or may originate
414 * in response to any other action (including from calls to
415 * g_settings_backend_write()).
417 * In the case that this call is in response to a call to
418 * g_settings_backend_write() then @origin_tag must be set to the same
419 * value that was passed to that call.
424 g_settings_backend_changed (GSettingsBackend
*backend
,
428 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend
));
429 g_return_if_fail (is_key (key
));
431 g_settings_backend_dispatch_signal (backend
,
432 G_STRUCT_OFFSET (GSettingsBackendWatch
,
434 key
, origin_tag
, NULL
, NULL
, NULL
);
438 * g_settings_backend_keys_changed:
439 * @backend: a #GSettingsBackend implementation
440 * @path: the path containing the changes
441 * @items: the %NULL-terminated list of changed keys
442 * @origin_tag: the origin tag
444 * Signals that a list of keys have possibly changed. Backend
445 * implementations should call this if keys have possibly changed their
448 * @path must be a valid path (ie: starting and ending with a slash and
449 * not containing '//'). Each string in @items must form a valid key
450 * name when @path is prefixed to it (ie: each item must not start or
451 * end with '/' and must not contain '//').
453 * The meaning of this signal is that any of the key names resulting
454 * from the contatenation of @path with each item in @items may have
457 * The same rules for when notifications must occur apply as per
458 * g_settings_backend_changed(). These two calls can be used
459 * interchangeably if exactly one item has changed (although in that
460 * case g_settings_backend_changed() is definitely preferred).
462 * For efficiency reasons, the implementation should strive for @path to
463 * be as long as possible (ie: the longest common prefix of all of the
464 * keys that were changed) but this is not strictly required.
469 g_settings_backend_keys_changed (GSettingsBackend
*backend
,
471 gchar
const * const *items
,
474 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend
));
475 g_return_if_fail (is_path (path
));
477 /* XXX: should do stricter checking (ie: inspect each item) */
478 g_return_if_fail (items
!= NULL
);
480 g_settings_backend_dispatch_signal (backend
,
481 G_STRUCT_OFFSET (GSettingsBackendWatch
,
483 path
, (gpointer
) items
,
484 (GBoxedCopyFunc
) g_strdupv
,
485 (GBoxedFreeFunc
) g_strfreev
,
490 * g_settings_backend_path_changed:
491 * @backend: a #GSettingsBackend implementation
492 * @path: the path containing the changes
493 * @origin_tag: the origin tag
495 * Signals that all keys below a given path may have possibly changed.
496 * Backend implementations should call this if an entire path of keys
497 * have possibly changed their values.
499 * @path must be a valid path (ie: starting and ending with a slash and
500 * not containing '//').
502 * The meaning of this signal is that any of the key which has a name
503 * starting with @path may have changed.
505 * The same rules for when notifications must occur apply as per
506 * g_settings_backend_changed(). This call might be an appropriate
507 * reasponse to a 'reset' call but implementations are also free to
508 * explicitly list the keys that were affected by that call if they can
511 * For efficiency reasons, the implementation should strive for @path to
512 * be as long as possible (ie: the longest common prefix of all of the
513 * keys that were changed) but this is not strictly required. As an
514 * example, if this function is called with the path of "/" then every
515 * single key in the application will be notified of a possible change.
520 g_settings_backend_path_changed (GSettingsBackend
*backend
,
524 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend
));
525 g_return_if_fail (is_path (path
));
527 g_settings_backend_dispatch_signal (backend
,
528 G_STRUCT_OFFSET (GSettingsBackendWatch
,
530 path
, origin_tag
, NULL
, NULL
, NULL
);
534 * g_settings_backend_writable_changed:
535 * @backend: a #GSettingsBackend implementation
536 * @key: the name of the key
538 * Signals that the writability of a single key has possibly changed.
540 * Since GSettings performs no locking operations for itself, this call
541 * will always be made in response to external events.
546 g_settings_backend_writable_changed (GSettingsBackend
*backend
,
549 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend
));
550 g_return_if_fail (is_key (key
));
552 g_settings_backend_dispatch_signal (backend
,
553 G_STRUCT_OFFSET (GSettingsBackendWatch
,
555 key
, NULL
, NULL
, NULL
, NULL
);
559 * g_settings_backend_path_writable_changed:
560 * @backend: a #GSettingsBackend implementation
561 * @path: the name of the path
563 * Signals that the writability of all keys below a given path may have
566 * Since GSettings performs no locking operations for itself, this call
567 * will always be made in response to external events.
572 g_settings_backend_path_writable_changed (GSettingsBackend
*backend
,
575 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend
));
576 g_return_if_fail (is_path (path
));
578 g_settings_backend_dispatch_signal (backend
,
579 G_STRUCT_OFFSET (GSettingsBackendWatch
,
580 path_writable_changed
),
581 path
, NULL
, NULL
, NULL
, NULL
);
593 g_settings_backend_flatten_one (gpointer key
,
597 FlattenState
*state
= user_data
;
598 const gchar
*skey
= key
;
601 g_return_val_if_fail (is_key (key
), TRUE
);
603 /* calculate longest common prefix */
604 if (state
->prefix
== NULL
)
608 /* first key? just take the prefix up to the last '/' */
609 state
->prefix
= g_strdup (skey
);
610 last_byte
= strrchr (state
->prefix
, '/') + 1;
611 state
->prefix_len
= last_byte
- state
->prefix
;
616 /* find the first character that does not match. we will
617 * definitely find one because the prefix ends in '/' and the key
618 * does not. also: no two keys in the tree are the same.
620 for (i
= 0; state
->prefix
[i
] == skey
[i
]; i
++);
622 /* check if we need to shorten the prefix */
623 if (state
->prefix
[i
] != '\0')
625 /* find the nearest '/', terminate after it */
626 while (state
->prefix
[i
- 1] != '/')
629 state
->prefix
[i
] = '\0';
630 state
->prefix_len
= i
;
635 /* save the entire item into the array.
636 * the prefixes will be removed later.
638 *state
->keys
++ = key
;
641 *state
->values
++ = value
;
647 * g_settings_backend_flatten_tree:
648 * @tree: a #GTree containing the changes
649 * @path: the location to save the path
650 * @keys: the location to save the relative keys
651 * @values: the location to save the values, or %NULL
653 * Calculate the longest common prefix of all keys in a tree and write
654 * out an array of the key names relative to that prefix and,
655 * optionally, the value to store at each of those keys.
657 * You must free the value returned in @path, @keys and @values using
658 * g_free(). You should not attempt to free or unref the contents of
664 g_settings_backend_flatten_tree (GTree
*tree
,
669 FlattenState state
= { 0, };
672 nnodes
= g_tree_nnodes (tree
);
674 *keys
= state
.keys
= g_new (const gchar
*, nnodes
+ 1);
675 state
.keys
[nnodes
] = NULL
;
679 *values
= state
.values
= g_new (GVariant
*, nnodes
+ 1);
680 state
.values
[nnodes
] = NULL
;
683 g_tree_foreach (tree
, g_settings_backend_flatten_one
, &state
);
684 g_return_if_fail (*keys
+ nnodes
== state
.keys
);
686 *path
= state
.prefix
;
688 *--state
.keys
+= state
.prefix_len
;
692 * g_settings_backend_changed_tree:
693 * @backend: a #GSettingsBackend implementation
694 * @tree: a #GTree containing the changes
695 * @origin_tag: the origin tag
697 * This call is a convenience wrapper. It gets the list of changes from
698 * @tree, computes the longest common prefix and calls
699 * g_settings_backend_changed().
704 g_settings_backend_changed_tree (GSettingsBackend
*backend
,
708 GSettingsBackendWatch
*watch
;
712 g_return_if_fail (G_IS_SETTINGS_BACKEND (backend
));
714 g_settings_backend_flatten_tree (tree
, &path
, &keys
, NULL
);
721 g_print ("changed_tree(): prefix %s\n", path
);
722 for (i
= 0; keys
[i
]; i
++)
723 g_print (" %s\n", keys
[i
]);
728 for (watch
= backend
->priv
->watches
; watch
; watch
= watch
->next
)
729 watch
->keys_changed (backend
, watch
->target
, path
, keys
, origin_tag
);
736 * g_settings_backend_read:
737 * @backend: a #GSettingsBackend implementation
738 * @key: the key to read
739 * @expected_type: a #GVariantType
740 * @default_value: if the default value should be returned
741 * @returns: the value that was read, or %NULL
743 * Reads a key. This call will never block.
745 * If the key exists, the value associated with it will be returned.
746 * If the key does not exist, %NULL will be returned.
748 * The returned value will be of the type given in @expected_type. If
749 * the backend stored a value of a different type then %NULL will be
752 * If @default_value is %TRUE then this gets the default value from the
753 * backend (ie: the one that the backend would contain if
754 * g_settings_reset() were called).
757 g_settings_backend_read (GSettingsBackend
*backend
,
759 const GVariantType
*expected_type
,
760 gboolean default_value
)
764 value
= G_SETTINGS_BACKEND_GET_CLASS (backend
)
765 ->read (backend
, key
, expected_type
, default_value
);
767 if G_UNLIKELY (value
&& !g_variant_is_of_type (value
, expected_type
))
769 g_variant_unref (value
);
777 * g_settings_backend_write:
778 * @backend: a #GSettingsBackend implementation
779 * @key: the name of the key
780 * @value: a #GVariant value to write to this key
781 * @origin_tag: the origin tag
782 * @returns: %TRUE if the write succeeded, %FALSE if the key was not writable
784 * Writes exactly one key.
786 * This call does not fail. During this call a
787 * #GSettingsBackend::changed signal will be emitted if the value of the
788 * key has changed. The updated key value will be visible to any signal
791 * One possible method that an implementation might deal with failures is
792 * to emit a second "changed" signal (either during this call, or later)
793 * to indicate that the affected keys have suddenly "changed back" to their
797 g_settings_backend_write (GSettingsBackend
*backend
,
802 return G_SETTINGS_BACKEND_GET_CLASS (backend
)
803 ->write (backend
, key
, value
, origin_tag
);
807 * g_settings_backend_write_keys:
808 * @backend: a #GSettingsBackend implementation
809 * @values: a #GTree containing key-value pairs to write
810 * @origin_tag: the origin tag
812 * Writes one or more keys. This call will never block.
814 * The key of each item in the tree is the key name to write to and the
815 * value is a #GVariant to write. The proper type of #GTree for this
816 * call can be created with g_settings_backend_create_tree(). This call
817 * might take a reference to the tree; you must not modified the #GTree
818 * after passing it to this call.
820 * This call does not fail. During this call a #GSettingsBackend::changed
821 * signal will be emitted if any keys have been changed. The new values of
822 * all updated keys will be visible to any signal callbacks.
824 * One possible method that an implementation might deal with failures is
825 * to emit a second "changed" signal (either during this call, or later)
826 * to indicate that the affected keys have suddenly "changed back" to their
830 g_settings_backend_write_tree (GSettingsBackend
*backend
,
834 return G_SETTINGS_BACKEND_GET_CLASS (backend
)
835 ->write_tree (backend
, tree
, origin_tag
);
839 * g_settings_backend_reset:
840 * @backend: a #GSettingsBackend implementation
841 * @key: the name of a key
842 * @origin_tag: the origin tag
844 * "Resets" the named key to its "default" value (ie: after system-wide
845 * defaults, mandatory keys, etc. have been taken into account) or possibly
849 g_settings_backend_reset (GSettingsBackend
*backend
,
853 G_SETTINGS_BACKEND_GET_CLASS (backend
)
854 ->reset (backend
, key
, origin_tag
);
858 * g_settings_backend_get_writable:
859 * @backend: a #GSettingsBackend implementation
860 * @key: the name of a key
861 * @returns: %TRUE if the key is writable
863 * Finds out if a key is available for writing to. This is the
864 * interface through which 'lockdown' is implemented. Locked down
865 * keys will have %FALSE returned by this call.
867 * You should not write to locked-down keys, but if you do, the
868 * implementation will deal with it.
871 g_settings_backend_get_writable (GSettingsBackend
*backend
,
874 return G_SETTINGS_BACKEND_GET_CLASS (backend
)
875 ->get_writable (backend
, key
);
879 * g_settings_backend_unsubscribe:
880 * @backend: a #GSettingsBackend
881 * @name: a key or path to subscribe to
883 * Reverses the effect of a previous call to
884 * g_settings_backend_subscribe().
887 g_settings_backend_unsubscribe (GSettingsBackend
*backend
,
890 G_SETTINGS_BACKEND_GET_CLASS (backend
)
891 ->unsubscribe (backend
, name
);
895 * g_settings_backend_subscribe:
896 * @backend: a #GSettingsBackend
897 * @name: a key or path to subscribe to
899 * Requests that change signals be emitted for events on @name.
902 g_settings_backend_subscribe (GSettingsBackend
*backend
,
905 G_SETTINGS_BACKEND_GET_CLASS (backend
)
906 ->subscribe (backend
, name
);
910 g_settings_backend_finalize (GObject
*object
)
912 GSettingsBackend
*backend
= G_SETTINGS_BACKEND (object
);
914 g_static_mutex_unlock (&backend
->priv
->lock
);
916 G_OBJECT_CLASS (g_settings_backend_parent_class
)
921 ignore_subscription (GSettingsBackend
*backend
,
927 g_settings_backend_init (GSettingsBackend
*backend
)
929 backend
->priv
= G_TYPE_INSTANCE_GET_PRIVATE (backend
,
930 G_TYPE_SETTINGS_BACKEND
,
931 GSettingsBackendPrivate
);
932 g_static_mutex_init (&backend
->priv
->lock
);
936 g_settings_backend_class_init (GSettingsBackendClass
*class)
938 GObjectClass
*gobject_class
= G_OBJECT_CLASS (class);
940 class->subscribe
= ignore_subscription
;
941 class->unsubscribe
= ignore_subscription
;
943 gobject_class
->finalize
= g_settings_backend_finalize
;
945 g_type_class_add_private (class, sizeof (GSettingsBackendPrivate
));
949 * g_settings_backend_create_tree:
950 * @returns: a new #GTree
952 * This is a convenience function for creating a tree that is compatible
953 * with g_settings_backend_write(). It merely calls g_tree_new_full()
954 * with strcmp(), g_free() and g_variant_unref().
957 g_settings_backend_create_tree (void)
959 return g_tree_new_full ((GCompareDataFunc
) strcmp
, NULL
,
960 g_free
, (GDestroyNotify
) g_variant_unref
);
964 * g_settings_backend_get_default:
965 * @returns: the default #GSettingsBackend
967 * Returns the default #GSettingsBackend. It is possible to override
968 * the default by setting the <envar>GSETTINGS_BACKEND</envar>
969 * environment variable to the name of a settings backend.
971 * The user gets a reference to the backend.
974 g_settings_backend_get_default (void)
976 static gsize backend
;
978 if (g_once_init_enter (&backend
))
980 GSettingsBackend
*instance
;
981 GIOExtensionPoint
*point
;
982 GIOExtension
*extension
;
983 GType extension_type
;
987 _g_io_modules_ensure_loaded ();
989 point
= g_io_extension_point_lookup (G_SETTINGS_BACKEND_EXTENSION_POINT_NAME
);
992 if ((env
= getenv ("GSETTINGS_BACKEND")))
994 extension
= g_io_extension_point_get_extension_by_name (point
, env
);
996 if (extension
== NULL
)
997 g_warning ("Can't find GSettings backend '%s' given in "
998 "GSETTINGS_BACKEND environment variable", env
);
1001 if (extension
== NULL
)
1003 extensions
= g_io_extension_point_get_extensions (point
);
1005 if (extensions
== NULL
)
1006 g_error ("No GSettingsBackend implementations exist.");
1008 extension
= extensions
->data
;
1010 if (strcmp (g_io_extension_get_name (extension
), "memory") == 0)
1011 g_message ("Using the 'memory' GSettings backend. Your settings "
1012 "will not be saved or shared with other applications.");
1015 extension_type
= g_io_extension_get_type (extension
);
1016 instance
= g_object_new (extension_type
, NULL
);
1018 g_once_init_leave (&backend
, (gsize
) instance
);
1021 return g_object_ref ((void *) backend
);
1025 * g_settings_backend_get_permission:
1026 * @backend: a #GSettingsBackend
1028 * @returns: a non-%NULL #GPermission. Free with g_object_unref()
1030 * Gets the permission object associated with writing to keys below
1031 * @path on @backend.
1033 * If this is not implemented in the backend, then a %TRUE
1034 * #GSimplePermission is returned.
1037 g_settings_backend_get_permission (GSettingsBackend
*backend
,
1040 GSettingsBackendClass
*class = G_SETTINGS_BACKEND_GET_CLASS (backend
);
1042 if (class->get_permission
)
1043 return class->get_permission (backend
, path
);
1045 return g_simple_permission_new (TRUE
);
1049 * g_settings_backend_sync_default:
1051 * Syncs the default backend.
1054 g_settings_backend_sync_default (void)
1056 GSettingsBackendClass
*class;
1057 GSettingsBackend
*backend
;
1059 backend
= g_settings_backend_get_default ();
1060 class = G_SETTINGS_BACKEND_GET_CLASS (backend
);
1063 class->sync (backend
);