/*
* Copyright © 2009, 2010 Codethink Limited
* Copyright © 2010 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the licence, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*
* Authors: Ryan Lortie <desrt@desrt.ca>
* Matthias Clasen <mclasen@redhat.com>
*/
#include "config.h"
#include "gsettingsbackendinternal.h"
#include "gnullsettingsbackend.h"
#include "giomodule-priv.h"
#include "gio-marshal.h"
#include <string.h>
#include <stdlib.h>
#include <glib.h>
#include <glibintl.h>
#include "gioalias.h"
G_DEFINE_ABSTRACT_TYPE (GSettingsBackend, g_settings_backend, G_TYPE_OBJECT)
typedef struct _GSettingsBackendWatch GSettingsBackendWatch;
struct _GSettingsBackendPrivate
{
GSettingsBackendWatch *watches;
gchar *context;
};
enum
{
PROP_0,
PROP_CONTEXT
};
/**
* SECTION:gsettingsbackend
* @title: GSettingsBackend
* @short_description: an interface for settings backend implementations
* @include: gio/gsettingsbackend.h
* @see_also: #GSettings, #GIOExtensionPoint
*
* The #GSettingsBackend interface defines a generic interface for
* non-strictly-typed data that is stored in a hierarchy. To implement
* an alternative storage backend for #GSettings, you need to implement
* the #GSettingsBackend interface and then make it implement the
* extension point #G_SETTINGS_BACKEND_EXTENSION_POINT_NAME.
*
* The interface defines methods for reading and writing values, a
* method for determining if writing of certain values will fail
* (lockdown) and a change notification mechanism.
*
* The semantics of the interface are very precisely defined and
* implementations must carefully adhere to the expectations of
* callers that are documented on each of the interface methods.
*
* Some of the GSettingsBackend functions accept or return a #GTree.
* These trees always have strings as keys and #GVariant as values.
* g_settings_backend_create_tree() is a convenience function to create
* suitable trees.
*
* <note><para>
* The #GSettingsBackend API is exported to allow third-party
* implementations, but does not carry the same stability guarantees
* as the public GIO API. For this reason, you have to define the
* C preprocessor symbol #G_SETTINGS_ENABLE_BACKEND before including
* <filename>gio/gsettingsbackend.h</filename>
* </para></note>
**/
struct _GSettingsBackendWatch
{
GSettingsBackendChangedFunc changed;
GSettingsBackendPathChangedFunc path_changed;
GSettingsBackendKeysChangedFunc keys_changed;
GSettingsBackendWritableChangedFunc writable_changed;
GSettingsBackendPathWritableChangedFunc path_writable_changed;
gpointer user_data;
GSettingsBackendWatch *next;
};
void
g_settings_backend_watch (GSettingsBackend *backend,
GSettingsBackendChangedFunc changed,
GSettingsBackendPathChangedFunc path_changed,
GSettingsBackendKeysChangedFunc keys_changed,
GSettingsBackendWritableChangedFunc writable_changed,
GSettingsBackendPathWritableChangedFunc path_writable_changed,
gpointer user_data)
{
GSettingsBackendWatch *watch;
watch = g_slice_new (GSettingsBackendWatch);
watch->changed = changed;
watch->path_changed = path_changed;
watch->keys_changed = keys_changed;
watch->writable_changed = writable_changed;
watch->path_writable_changed = path_writable_changed;
watch->user_data = user_data;
watch->next = backend->priv->watches;
backend->priv->watches = watch;
}
void
g_settings_backend_unwatch (GSettingsBackend *backend,
gpointer user_data)
{
GSettingsBackendWatch **ptr;
for (ptr = &backend->priv->watches; *ptr; ptr = &(*ptr)->next)
if ((*ptr)->user_data == user_data)
{
GSettingsBackendWatch *tmp = *ptr;
*ptr = tmp->next;
g_slice_free (GSettingsBackendWatch, tmp);
return;
}
g_assert_not_reached ();
}
static gboolean
is_key (const gchar *key)
{
gint length;
gint i;
g_return_val_if_fail (key != NULL, FALSE);
g_return_val_if_fail (key[0] == '/', FALSE);
for (i = 1; key[i]; i++)
g_return_val_if_fail (key[i] != '/' || key[i + 1] != '/', FALSE);
length = i;
g_return_val_if_fail (key[length - 1] != '/', FALSE);
return TRUE;
}
static gboolean
is_path (const gchar *path)
{
gint length;
gint i;
g_return_val_if_fail (path != NULL, FALSE);
g_return_val_if_fail (path[0] == '/', FALSE);
for (i = 1; path[i]; i++)
g_return_val_if_fail (path[i] != '/' || path[i + 1] != '/', FALSE);
length = i;
g_return_val_if_fail (path[length - 1] == '/', FALSE);
return TRUE;
}
/**
* g_settings_backend_changed:
* @backend: a #GSettingsBackend implementation
* @key: the name of the key
* @origin_tag: the origin tag
*
* Signals that a single key has possibly changed. Backend
* implementations should call this if a key has possibly changed its
* value.
*
* @key must be a valid key (ie: starting with a slash, not containing
* '//', and not ending with a slash).
*
* The implementation must call this function during any call to
* g_settings_backend_write(), before the call returns (except in the
* case that no keys are actually changed and it cares to detect this
* fact). It may not rely on the existence of a mainloop for
* dispatching the signal later.
*
* The implementation may call this function at any other time it likes
* in response to other events (such as changes occuring outside of the
* program). These calls may originate from a mainloop or may originate
* in response to any other action (including from calls to
* g_settings_backend_write()).
*
* In the case that this call is in response to a call to
* g_settings_backend_write() then @origin_tag must be set to the same
* value that was passed to that call.
*
* Since: 2.26
**/
void
g_settings_backend_changed (GSettingsBackend *backend,
const gchar *key,
gpointer origin_tag)
{
GSettingsBackendWatch *watch;
g_return_if_fail (G_IS_SETTINGS_BACKEND (backend));
g_return_if_fail (is_key (key));
for (watch = backend->priv->watches; watch; watch = watch->next)
watch->changed (backend, key, origin_tag, watch->user_data);
}
/**
* g_settings_backend_keys_changed:
* @backend: a #GSettingsBackend implementation
* @path: the path containing the changes
* @items: the %NULL-terminated list of changed keys
* @origin_tag: the origin tag
*
* Signals that a list of keys have possibly changed. Backend
* implementations should call this if keys have possibly changed their
* values.
*
* @path must be a valid path (ie: starting and ending with a slash and
* not containing '//'). Each string in @items must form a valid key
* name when @path is prefixed to it (ie: each item must not start or
* end with '/' and must not contain '//').
*
* The meaning of this signal is that any of the key names resulting
* from the contatenation of @path with each item in @items may have
* changed.
*
* The same rules for when notifications must occur apply as per
* g_settings_backend_changed(). These two calls can be used
* interchangeably if exactly one item has changed (although in that
* case g_settings_backend_changed() is definitely preferred).
*
* For efficiency reasons, the implementation should strive for @path to
* be as long as possible (ie: the longest common prefix of all of the
* keys that were changed) but this is not strictly required.
*
* Since: 2.26
*/
void
g_settings_backend_keys_changed (GSettingsBackend *backend,
const gchar *path,
gchar const * const *items,
gpointer origin_tag)
{
GSettingsBackendWatch *watch;
g_return_if_fail (G_IS_SETTINGS_BACKEND (backend));
g_return_if_fail (path[0] == '\0' || is_path (path));
g_return_if_fail (items != NULL);
for (watch = backend->priv->watches; watch; watch = watch->next)
watch->keys_changed (backend, path, items, origin_tag, watch->user_data);
}
/**
* g_settings_backend_path_changed:
* @backend: a #GSettingsBackend implementation
* @path: the path containing the changes
* @origin_tag: the origin tag
*
* Signals that all keys below a given path may have possibly changed.
* Backend implementations should call this if an entire path of keys
* have possibly changed their values.
*
* @path must be a valid path (ie: starting and ending with a slash and
* not containing '//').
*
* The meaning of this signal is that any of the key which has a name
* starting with @path may have changed.
*
* The same rules for when notifications must occur apply as per
* g_settings_backend_changed(). This call might be an appropriate
* reasponse to a 'reset' call but implementations are also free to
* explicitly list the keys that were affected by that call if they can
* easily do so.
*
* For efficiency reasons, the implementation should strive for @path to
* be as long as possible (ie: the longest common prefix of all of the
* keys that were changed) but this is not strictly required. As an
* example, if this function is called with the path of "/" then every
* single key in the application will be notified of a possible change.
*
* Since: 2.26
*/
void
g_settings_backend_path_changed (GSettingsBackend *backend,
const gchar *path,
gpointer origin_tag)
{
GSettingsBackendWatch *watch;
g_return_if_fail (G_IS_SETTINGS_BACKEND (backend));
g_return_if_fail (is_path (path));
for (watch = backend->priv->watches; watch; watch = watch->next)
watch->path_changed (backend, path, origin_tag, watch->user_data);
}
/**
* g_settings_backend_writable_changed:
* @backend: a #GSettingsBackend implementation
* @key: the name of the key
*
* Signals that the writability of a single key has possibly changed.
*
* Since GSettings performs no locking operations for itself, this call
* will always be made in response to external events.
*
* Since: 2.26
**/
void
g_settings_backend_writable_changed (GSettingsBackend *backend,
const gchar *key)
{
GSettingsBackendWatch *watch;
g_return_if_fail (G_IS_SETTINGS_BACKEND (backend));
g_return_if_fail (is_key (key));
for (watch = backend->priv->watches; watch; watch = watch->next)
watch->writable_changed (backend, key, watch->user_data);
}
/**
* g_settings_backend_path_writable_changed:
* @backend: a #GSettingsBackend implementation
* @path: the name of the path
*
* Signals that the writability of all keys below a given path may have
* changed.
*
* Since GSettings performs no locking operations for itself, this call
* will always be made in response to external events.
*
* Since: 2.26
**/
void
g_settings_backend_path_writable_changed (GSettingsBackend *backend,
const gchar *path)
{
GSettingsBackendWatch *watch;
g_return_if_fail (G_IS_SETTINGS_BACKEND (backend));
g_return_if_fail (is_path (path));
for (watch = backend->priv->watches; watch; watch = watch->next)
watch->path_writable_changed (backend, path, watch->user_data);
}
typedef struct
{
const gchar **keys;
GVariant **values;
gint prefix_len;
gchar *prefix;
} FlattenState;
static gboolean
g_settings_backend_flatten_one (gpointer key,
gpointer value,
gpointer user_data)
{
FlattenState *state = user_data;
const gchar *skey = key;
gint i;
g_return_val_if_fail (is_key (key), TRUE);
/* calculate longest common prefix */
if (state->prefix == NULL)
{
gchar *last_byte;
/* first key? just take the prefix up to the last '/' */
state->prefix = g_strdup (skey);
last_byte = strrchr (state->prefix, '/') + 1;
state->prefix_len = last_byte - state->prefix;
*last_byte = '\0';
}
else
{
/* find the first character that does not match. we will
* definitely find one because the prefix ends in '/' and the key
* does not. also: no two keys in the tree are the same.
*/
for (i = 0; state->prefix[i] == skey[i]; i++);
/* check if we need to shorten the prefix */
if (state->prefix[i] != '\0')
{
/* find the nearest '/', terminate after it */
while (state->prefix[i - 1] != '/')
i--;
state->prefix[i] = '\0';
state->prefix_len = i;
}
}
/* save the entire item into the array.
* the prefixes will be removed later.
*/
*state->keys++ = key;
if (state->values)
*state->values++ = value;
return FALSE;
}
/**
* g_settings_backend_flatten_tree:
* @tree: a #GTree containing the changes
* @path: the location to save the path
* @keys: the location to save the relative keys
* @values: the location to save the values, or %NULL
*
* Calculate the longest common prefix of all keys in a tree and write
* out an array of the key names relative to that prefix and,
* optionally, the value to store at each of those keys.
*
* You must free the value returned in @path, @keys and @values using
* g_free(). You should not attempt to free or unref the contents of
* @keys or @values.
*
* Since: 2.26
**/
void
g_settings_backend_flatten_tree (GTree *tree,
gchar **path,
const gchar ***keys,
GVariant ***values)
{
FlattenState state = { 0, };
gsize nnodes;
nnodes = g_tree_nnodes (tree);
*keys = state.keys = g_new (const gchar *, nnodes + 1);
state.keys[nnodes] = NULL;
if (values != NULL)
{
*values = state.values = g_new (GVariant *, nnodes + 1);
state.values[nnodes] = NULL;
}
g_tree_foreach (tree, g_settings_backend_flatten_one, &state);
g_return_if_fail (*keys + nnodes == state.keys);
*path = state.prefix;
while (nnodes--)
*--state.keys += state.prefix_len;
}
/**
* g_settings_backend_changed_tree:
* @backend: a #GSettingsBackend implementation
* @tree: a #GTree containing the changes
* @origin_tag: the origin tag
*
* This call is a convenience wrapper. It gets the list of changes from
* @tree, computes the longest common prefix and calls
* g_settings_backend_changed().
*
* Since: 2.26
**/
void
g_settings_backend_changed_tree (GSettingsBackend *backend,
GTree *tree,
gpointer origin_tag)
{
GSettingsBackendWatch *watch;
const gchar **keys;
gchar *path;
g_return_if_fail (G_IS_SETTINGS_BACKEND (backend));
g_settings_backend_flatten_tree (tree, &path, &keys, NULL);
for (watch = backend->priv->watches; watch; watch = watch->next)
watch->keys_changed (backend, path, keys, origin_tag, watch->user_data);
g_free (path);
g_free (keys);
}
/*< private >
* g_settings_backend_read:
* @backend: a #GSettingsBackend implementation
* @key: the key to read
* @expected_type: a #GVariantType hint
* @returns: the value that was read, or %NULL
*
* Reads a key. This call will never block.
*
* If the key exists, the value associated with it will be returned.
* If the key does not exist, %NULL will be returned.
*
* If @expected_type is given, it serves as a type hint to the backend.
* If you expect a key of a certain type then you should give
* @expected_type to increase your chances of getting it. Some backends
* may ignore this argument and return values of a different type; it is
* mostly used by backends that don't store strong type information.
*/
GVariant *
g_settings_backend_read (GSettingsBackend *backend,
const gchar *key,
const GVariantType *expected_type,
gboolean default_value)
{
return G_SETTINGS_BACKEND_GET_CLASS (backend)
->read (backend, key, expected_type, default_value);
}
/*< private >
* g_settings_backend_write:
* @backend: a #GSettingsBackend implementation
* @key: the name of the key
* @value: a #GVariant value to write to this key
* @origin_tag: the origin tag
* @returns: %TRUE if the write succeeded, %FALSE if the key was not writable
*
* Writes exactly one key.
*
* This call does not fail. During this call a
* #GSettingsBackend::changed signal will be emitted if the value of the
* key has changed. The updated key value will be visible to any signal
* callbacks.
*
* One possible method that an implementation might deal with failures is
* to emit a second "changed" signal (either during this call, or later)
* to indicate that the affected keys have suddenly "changed back" to their
* old values.
*/
gboolean
g_settings_backend_write (GSettingsBackend *backend,
const gchar *key,
GVariant *value,
gpointer origin_tag)
{
return G_SETTINGS_BACKEND_GET_CLASS (backend)
->write (backend, key, value, origin_tag);
}
/*< private >
* g_settings_backend_write_keys:
* @backend: a #GSettingsBackend implementation
* @values: a #GTree containing key-value pairs to write
* @origin_tag: the origin tag
*
* Writes one or more keys. This call will never block.
*
* The key of each item in the tree is the key name to write to and the
* value is a #GVariant to write. The proper type of #GTree for this
* call can be created with g_settings_backend_create_tree(). This call
* might take a reference to the tree; you must not modified the #GTree
* after passing it to this call.
*
* This call does not fail. During this call a #GSettingsBackend::changed
* signal will be emitted if any keys have been changed. The new values of
* all updated keys will be visible to any signal callbacks.
*
* One possible method that an implementation might deal with failures is
* to emit a second "changed" signal (either during this call, or later)
* to indicate that the affected keys have suddenly "changed back" to their
* old values.
*/
gboolean
g_settings_backend_write_keys (GSettingsBackend *backend,
GTree *tree,
gpointer origin_tag)
{
return G_SETTINGS_BACKEND_GET_CLASS (backend)
->write_keys (backend, tree, origin_tag);
}
/*< private >
* g_settings_backend_reset:
* @backend: a #GSettingsBackend implementation
* @key: the name of a key
* @origin_tag: the origin tag
*
* "Resets" the named key to its "default" value (ie: after system-wide
* defaults, mandatory keys, etc. have been taken into account) or possibly
* unsets it.
*/
void
g_settings_backend_reset (GSettingsBackend *backend,
const gchar *key,
gpointer origin_tag)
{
G_SETTINGS_BACKEND_GET_CLASS (backend)
->reset (backend, key, origin_tag);
}
/*< private >
* g_settings_backend_reset_path:
* @backend: a #GSettingsBackend implementation
* @name: the name of a key or path
* @origin_tag: the origin tag
*
* "Resets" the named path. This means that every key under the path is
* reset.
*/
void
g_settings_backend_reset_path (GSettingsBackend *backend,
const gchar *path,
gpointer origin_tag)
{
G_SETTINGS_BACKEND_GET_CLASS (backend)
->reset_path (backend, path, origin_tag);
}
/*< private >
* g_settings_backend_get_writable:
* @backend: a #GSettingsBackend implementation
* @key: the name of a key
* @returns: %TRUE if the key is writable
*
* Finds out if a key is available for writing to. This is the
* interface through which 'lockdown' is implemented. Locked down
* keys will have %FALSE returned by this call.
*
* You should not write to locked-down keys, but if you do, the
* implementation will deal with it.
*/
gboolean
g_settings_backend_get_writable (GSettingsBackend *backend,
const gchar *key)
{
return G_SETTINGS_BACKEND_GET_CLASS (backend)
->get_writable (backend, key);
}
/*< private >
* g_settings_backend_unsubscribe:
* @backend: a #GSettingsBackend
* @name: a key or path to subscribe to
*
* Reverses the effect of a previous call to
* g_settings_backend_subscribe().
*/
void
g_settings_backend_unsubscribe (GSettingsBackend *backend,
const char *name)
{
G_SETTINGS_BACKEND_GET_CLASS (backend)
->unsubscribe (backend, name);
}
/*< private >
* g_settings_backend_subscribe:
* @backend: a #GSettingsBackend
* @name: a key or path to subscribe to
*
* Requests that change signals be emitted for events on @name.
*/
void
g_settings_backend_subscribe (GSettingsBackend *backend,
const gchar *name)
{
G_SETTINGS_BACKEND_GET_CLASS (backend)
->subscribe (backend, name);
}
static void
g_settings_backend_set_property (GObject *object,
guint prop_id,
const GValue *value,
GParamSpec *pspec)
{
GSettingsBackend *backend = G_SETTINGS_BACKEND (object);
switch (prop_id)
{
case PROP_CONTEXT:
backend->priv->context = g_value_dup_string (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
g_settings_backend_get_property (GObject *object,
guint prop_id,
GValue *value,
GParamSpec *pspec)
{
GSettingsBackend *backend = G_SETTINGS_BACKEND (object);
switch (prop_id)
{
case PROP_CONTEXT:
g_value_set_string (value, backend->priv->context);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
g_settings_backend_finalize (GObject *object)
{
GSettingsBackend *backend = G_SETTINGS_BACKEND (object);
g_free (backend->priv->context);
G_OBJECT_CLASS (g_settings_backend_parent_class)->finalize (object);
}
static void
ignore_subscription (GSettingsBackend *backend,
const gchar *key)
{
}
static void
g_settings_backend_init (GSettingsBackend *backend)
{
backend->priv = G_TYPE_INSTANCE_GET_PRIVATE (backend,
G_TYPE_SETTINGS_BACKEND,
GSettingsBackendPrivate);
}
static void
g_settings_backend_class_init (GSettingsBackendClass *class)
{
GObjectClass *gobject_class = G_OBJECT_CLASS (class);
class->subscribe = ignore_subscription;
class->unsubscribe = ignore_subscription;
gobject_class->get_property = g_settings_backend_get_property;
gobject_class->set_property = g_settings_backend_set_property;
gobject_class->finalize = g_settings_backend_finalize;
g_type_class_add_private (class, sizeof (GSettingsBackendPrivate));
/**
* GSettingsBackend:context:
*
* The "context" property gives a hint to the backend as to
* what storage to use. It is up to the implementation to make
* use of this information.
*
* E.g. DConf supports "user", "system", "defaults" and "login"
* contexts.
*
* If your backend supports different contexts, you should also
* provide an implementation of the supports_context() class
* function in #GSettingsBackendClass.
*/
g_object_class_install_property (gobject_class, PROP_CONTEXT,
g_param_spec_string ("context", P_("Context"),
P_("An identifier to decide which storage to use"),
"", G_PARAM_READWRITE |
G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));
}
/*< private >
* g_settings_backend_create_tree:
* @returns: a new #GTree
*
* This is a convenience function for creating a tree that is compatible
* with g_settings_backend_write(). It merely calls g_tree_new_full()
* with strcmp(), g_free() and g_variant_unref().
*/
GTree *
g_settings_backend_create_tree (void)
{
return g_tree_new_full ((GCompareDataFunc) strcmp, NULL,
g_free, (GDestroyNotify) g_variant_unref);
}
static gpointer
get_default_backend (const gchar *context)
{
GIOExtension *extension = NULL;
GIOExtensionPoint *point;
GList *extensions;
const gchar *env;
GType type;
_g_io_modules_ensure_loaded ();
point = g_io_extension_point_lookup (G_SETTINGS_BACKEND_EXTENSION_POINT_NAME);
if ((env = getenv ("GSETTINGS_BACKEND")))
{
extension = g_io_extension_point_get_extension_by_name (point, env);
if (extension == NULL)
g_warning ("Can't find GSettings backend '%s' given in "
"GSETTINGS_BACKEND environment variable", env);
}
if (extension == NULL)
{
extensions = g_io_extension_point_get_extensions (point);
if (extensions == NULL)
g_error ("No GSettingsBackend implementations exist.");
extension = extensions->data;
}
if (context[0] != '\0') /* (context != "") */
{
GSettingsBackendClass *backend_class;
GTypeClass *class;
class = g_io_extension_ref_class (extension);
backend_class = G_SETTINGS_BACKEND_CLASS (class);
if (backend_class->supports_context == NULL ||
!backend_class->supports_context (context))
{
g_type_class_unref (class);
return NULL;
}
g_type_class_unref (class);
}
type = g_io_extension_get_type (extension);
return g_object_new (type, "context", context, NULL);
}
static GHashTable *g_settings_backends;
/*< private >
* g_settings_backend_get_with_context:
* @context: a context that might be used by the backend to determine
* which storage to use, or %NULL to use the default storage
* @returns: the default #GSettingsBackend
*
* Returns the default #GSettingsBackend. It is possible to override
* the default by setting the <envar>GSETTINGS_BACKEND</envar>
* environment variable to the name of a settings backend.
*
* The @context parameter can be used to indicate that a different
* than the default storage is desired. E.g. the DConf backend lets
* you use "user", "system", "defaults" and "login" as contexts.
*
* If @context is not supported by the implementation, this function
* returns an instance of the #GSettingsMemoryBackend.
* See g_settings_backend_supports_context(),
*
* The user does not own the return value and it must not be freed.
*/
GSettingsBackend *
g_settings_backend_get_with_context (const gchar *context)
{
GSettingsBackend *backend;
g_return_val_if_fail (context != NULL, NULL);
_g_io_modules_ensure_extension_points_registered ();
if (g_settings_backends == NULL)
g_settings_backends = g_hash_table_new (g_str_hash, g_str_equal);
backend = g_hash_table_lookup (g_settings_backends, context);
if (!backend)
{
backend = get_default_backend (context);
if (!backend)
backend = g_null_settings_backend_new ();
g_hash_table_insert (g_settings_backends, g_strdup (context), backend);
}
return g_object_ref (backend);
}
/*< private >
* g_settings_backend_supports_context:
* @context: a context string that might be passed to
* g_settings_backend_new_with_context()
* @returns: #TRUE if @context is supported
*
* Determines if the given context is supported by the default
* GSettingsBackend implementation.
*/
gboolean
g_settings_backend_supports_context (const gchar *context)
{
GSettingsBackend *backend;
g_return_val_if_fail (context != NULL, FALSE);
backend = get_default_backend (context);
if (backend)
{
g_object_unref (backend);
return TRUE;
}
return FALSE;
}
/**
* g_settings_backend_setup:
* @context: a context string (not %NULL or "")
* @backend: a #GSettingsBackend
*
* Sets up @backend for use with #GSettings.
*
* If you create a #GSettings with its context property set to @context
* then it will use the backend given to this function. See
* g_settings_new_with_context().
*
* The backend must be set up before any settings objects are created
* for the named context.
*
* It is not possible to specify a backend for the default context.
*
* This function takes a reference on @backend and never releases it.
*
* Since: 2.26
**/
void
g_settings_backend_setup (const gchar *context,
GSettingsBackend *backend)
{
g_return_if_fail (context[0] != '\0');
g_return_if_fail (G_IS_SETTINGS_BACKEND (backend));
if (g_settings_backends == NULL)
g_settings_backends = g_hash_table_new (g_str_hash, g_str_equal);
if (g_hash_table_lookup (g_settings_backends, context))
g_error ("A GSettingsBackend already exists for context '%s'", context);
g_hash_table_insert (g_settings_backends,
g_strdup (context),
g_object_ref (backend));
}
#define __G_SETTINGS_BACKEND_C__
#include "gioaliasdef.c"