gio/gnullsettingsbackend.c

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