gio/gnullsettingsbackend.c

   1 /*
   2  * Copyright © 2010 Codethink Limited
   3  *
   4  * SPDX-License-Identifier: LGPL-2.1-or-later
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  * Author: Ryan Lortie <desrt@desrt.ca>
  20  */
  21
  22 #include "config.h"
  23
  24 #include "gsettingsbackendinternal.h"
  25 #include "giomodule-priv.h"
  26 #include "gsimplepermission.h"
  27
  28
  29 #define G_TYPE_NULL_SETTINGS_BACKEND    (g_null_settings_backend_get_type ())
  30 #define G_NULL_SETTINGS_BACKEND(inst)   (G_TYPE_CHECK_INSTANCE_CAST ((inst), \
  31                                          G_TYPE_NULL_SETTINGS_BACKEND,       \
  32                                          GNullSettingsBackend))
  33
  34
  35 typedef GSettingsBackendClass GNullSettingsBackendClass;
  36 typedef GSettingsBackend      GNullSettingsBackend;
  37
  38 G_DEFINE_TYPE_WITH_CODE (GNullSettingsBackend,
  39                          g_null_settings_backend,
  40                          G_TYPE_SETTINGS_BACKEND,
  41                          _g_io_modules_ensure_extension_points_registered ();
  42                          g_io_extension_point_implement (G_SETTINGS_BACKEND_EXTENSION_POINT_NAME,
  43                                                          g_define_type_id, "null", 10))
  44
  45 static GVariant *
  46 g_null_settings_backend_read (GSettingsBackend   *backend,
  47                               const gchar        *key,
  48                               const GVariantType *expected_type,
  49                               gboolean            default_value)
  50 {
  51   return NULL;
  52 }
  53
  54 static gboolean
  55 g_null_settings_backend_write (GSettingsBackend *backend,
  56                                const gchar      *key,
  57                                GVariant         *value,
  58                                gpointer          origin_tag)
  59 {
  60   if (value)
  61     g_variant_unref (g_variant_ref_sink (value));
  62   return FALSE;
  63 }
  64
  65 static gboolean
  66 g_null_settings_backend_write_one (gpointer key,
  67                                    gpointer value,
  68                                    gpointer data)
  69 {
  70   if (value)
  71     g_variant_unref (g_variant_ref_sink (value));
  72   return FALSE;
  73 }
  74
  75 static gboolean
  76 g_null_settings_backend_write_tree (GSettingsBackend *backend,
  77                                     GTree            *tree,
  78                                     gpointer          origin_tag)
  79 {
  80   g_tree_foreach (tree, g_null_settings_backend_write_one, backend);
  81   return FALSE;
  82 }
  83
  84 static void
  85 g_null_settings_backend_reset (GSettingsBackend *backend,
  86                                const gchar      *key,
  87                                gpointer          origin_tag)
  88 {
  89 }
  90
  91 static gboolean
  92 g_null_settings_backend_get_writable (GSettingsBackend *backend,
  93                                       const gchar      *name)
  94 {
  95   return FALSE;
  96 }
  97
  98 static GPermission *
  99 g_null_settings_backend_get_permission (GSettingsBackend *backend,
 100                                         const gchar      *path)
 101 {
 102   return g_simple_permission_new (FALSE);
 103 }
 104
 105 static void
 106 g_null_settings_backend_init (GNullSettingsBackend *memory)
 107 {
 108 }
 109
 110 static void
 111 g_null_settings_backend_class_init (GNullSettingsBackendClass *class)
 112 {
 113   GSettingsBackendClass *backend_class = G_SETTINGS_BACKEND_CLASS (class);
 114
 115   backend_class->read = g_null_settings_backend_read;
 116   backend_class->write = g_null_settings_backend_write;
 117   backend_class->write_tree = g_null_settings_backend_write_tree;
 118   backend_class->reset = g_null_settings_backend_reset;
 119   backend_class->get_writable = g_null_settings_backend_get_writable;
 120   backend_class->get_permission = g_null_settings_backend_get_permission;
 121 }
 122
 123 /**
 124  * g_null_settings_backend_new:
 125  *
 126  *
 127  * Creates a readonly #GSettingsBackend.
 128  *
 129  * This backend does not allow changes to settings, so all settings
 130  * will always have their default values.
 131  *
 132  * Returns: (transfer full): a newly created #GSettingsBackend
 133  *
 134  * Since: 2.28
 135  */
 136 GSettingsBackend *
 137 g_null_settings_backend_new (void)
 138 {
 139   return g_object_new (G_TYPE_NULL_SETTINGS_BACKEND, NULL);
 140 }