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, write to the
  16  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17  * Boston, MA 02111-1307, USA.
  18  *
  19  * Author: Ryan Lortie <desrt@desrt.ca>
  20  */
  21
  22 #include "config.h"
  23
  24 #include "gsettingsbackendinternal.h"
  25 #include "giomodule.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_extension_point_implement (G_SETTINGS_BACKEND_EXTENSION_POINT_NAME,
  42                                                          g_define_type_id, "null", 10))
  43
  44 static GVariant *
  45 g_null_settings_backend_read (GSettingsBackend   *backend,
  46                               const gchar        *key,
  47                               const GVariantType *expected_type,
  48                               gboolean            default_value)
  49 {
  50   return NULL;
  51 }
  52
  53 static gboolean
  54 g_null_settings_backend_write (GSettingsBackend *backend,
  55                                const gchar      *key,
  56                                GVariant         *value,
  57                                gpointer          origin_tag)
  58 {
  59   if (value)
  60     g_variant_unref (g_variant_ref_sink (value));
  61   return FALSE;
  62 }
  63
  64 static gboolean
  65 g_null_settings_backend_write_one (gpointer key,
  66                                    gpointer value,
  67                                    gpointer data)
  68 {
  69   if (value)
  70     g_variant_unref (g_variant_ref_sink (value));
  71   return FALSE;
  72 }
  73
  74 static gboolean
  75 g_null_settings_backend_write_tree (GSettingsBackend *backend,
  76                                     GTree            *tree,
  77                                     gpointer          origin_tag)
  78 {
  79   g_tree_foreach (tree, g_null_settings_backend_write_one, backend);
  80   return FALSE;
  81 }
  82
  83 static void
  84 g_null_settings_backend_reset (GSettingsBackend *backend,
  85                                const gchar      *key,
  86                                gpointer          origin_tag)
  87 {
  88 }
  89
  90 static gboolean
  91 g_null_settings_backend_get_writable (GSettingsBackend *backend,
  92                                       const gchar      *name)
  93 {
  94   return FALSE;
  95 }
  96
  97 static GPermission *
  98 g_null_settings_backend_get_permission (GSettingsBackend *backend,
  99                                         const gchar      *path)
 100 {
 101   return g_simple_permission_new (FALSE);
 102 }
 103
 104 static void
 105 g_null_settings_backend_init (GNullSettingsBackend *memory)
 106 {
 107 }
 108
 109 static void
 110 g_null_settings_backend_class_init (GNullSettingsBackendClass *class)
 111 {
 112   GSettingsBackendClass *backend_class = G_SETTINGS_BACKEND_CLASS (class);
 113
 114   backend_class->read = g_null_settings_backend_read;
 115   backend_class->write = g_null_settings_backend_write;
 116   backend_class->write_tree = g_null_settings_backend_write_tree;
 117   backend_class->reset = g_null_settings_backend_reset;
 118   backend_class->get_writable = g_null_settings_backend_get_writable;
 119   backend_class->get_permission = g_null_settings_backend_get_permission;
 120 }
 121
 122 /**
 123  * g_null_settings_backend_new:
 124  *
 125  *
 126  * Creates a readonly #GSettingsBackend.
 127  *
 128  * This backend does not allow changes to settings, so all settings
 129  * will always have their default values.
 130  *
 131  * Returns: (transfer full): a newly created #GSettingsBackend
 132  *
 133  * Since: 2.28
 134  */
 135 GSettingsBackend *
 136 g_null_settings_backend_new (void)
 137 {
 138   return g_object_new (G_TYPE_NULL_SETTINGS_BACKEND, NULL);
 139 }