Tweak GSettings key/schema listing APIs

docs/reference/gio/gio-sections.txt

@@ -2135,7 +2135,6 @@ GSettingsBackendPrivate
 <FILE>gsettings</FILE>
 <TITLE>GSettings</TITLE>
 GSettings
-g_settings_schema_exists
 g_settings_new
 g_settings_new_with_path
 g_settings_new_with_backend
@@ -2149,6 +2148,9 @@ g_settings_apply
 g_settings_revert
 g_settings_get_has_unapplied
 g_settings_get_child
+
+<SUBSECTION Introspection>
+g_settings_list_schemas
 g_settings_list_keys
 
 <SUBSECTION Convenience>

gio/gio.symbols

@@ -1442,7 +1442,7 @@ g_keyfile_settings_backend_new
 
 #if IN_HEADER(__G_SETTINGS_H__)
 #if IN_FILE(__G_SETTINGS_SCHEMA_C__)
-g_settings_schema_exists
+g_settings_list_schemas
 #endif
 
 #if IN_FILE(__G_SETTINGS_C__)

gio/gsettings.c

@@ -1867,21 +1867,21 @@ g_settings_get_child (GSettings   *settings,
  * (since you should already know what keys are in your schema).  This
  * function is intended for introspection reasons.
  *
- * You should free the return value with g_strfreev() when you are done
- * with it.
+ * You should free the return value with g_free() when you are done with
+ * it.
  */
-gchar **
+const gchar **
 g_settings_list_keys (GSettings *settings)
 {
   const GQuark *keys;
-  gchar **strv;
+  const gchar **strv;
   gint n_keys;
   gint i;
 
   keys = g_settings_schema_list (settings->priv->schema, &n_keys);
-  strv = g_new (gchar *, n_keys + 1);
+  strv = g_new (const gchar *, n_keys + 1);
   for (i = 0; i < n_keys; i++)
-    strv[i] = g_strdup (g_quark_to_string (keys[i]));
+    strv[i] = g_quark_to_string (keys[i]);
   strv[i] = NULL;
 
   return strv;

gio/gsettings.h

@@ -70,7 +70,7 @@ struct _GSettings
 
 GType                   g_settings_get_type                             (void);
 
-gboolean                g_settings_schema_exists                        (const gchar        *schema_name);
+const gchar * const *   g_settings_list_schemas                         (void);
 GSettings *             g_settings_new                                  (const gchar        *schema);
 GSettings *             g_settings_new_with_path                        (const gchar        *schema,
                                                                          const gchar        *path);
@@ -79,7 +79,7 @@ GSettings *             g_settings_new_with_backend                     (const g
 GSettings *             g_settings_new_with_backend_and_path            (const gchar        *schema,
                                                                          GSettingsBackend   *backend,
                                                                          const gchar        *path);
-gchar **                g_settings_list_keys                            (GSettings          *settings);
+const gchar **          g_settings_list_keys                            (GSettings          *settings);
 
 gboolean                g_settings_set_value                            (GSettings          *settings,
                                                                          const gchar        *key,

gio/gsettingsschema.c

@@ -53,7 +53,8 @@ initialise_schema_sources (void)
           gchar *filename;
           GvdbTable *table;
 
-          filename = g_build_filename (*dir, "glib-2.0", "schemas", "gschemas.compiled", NULL);
+          filename = g_build_filename (*dir, "glib-2.0", "schemas",
+                                       "gschemas.compiled", NULL);
           table = gvdb_table_new (filename, TRUE, NULL);
 
           if (table != NULL)
@@ -82,6 +83,67 @@ initialise_schema_sources (void)
     }
 }
 
+static void
+add_item (gpointer key,
+          gpointer value,
+          gpointer user_data)
+{
+  gchar ***ptr = user_data;
+
+  *(*ptr)++ = (gchar *) key;
+}
+
+/**
+ * g_settings_list_schemas:
+ * Returns: a list of the schemas installed on the system
+ *
+ * Returns a list of GSettings schemas that are available.  The list
+ * must not be modified or freed.
+ **/
+const gchar * const *
+g_settings_list_schemas (void)
+{
+  static gsize schema_list;
+
+  if (g_once_init_enter (&schema_list))
+    {
+      GHashTable *builder;
+      GSList *source;
+      gchar **list;
+      gchar **ptr;
+      gint i;
+
+      initialise_schema_sources ();
+
+      builder = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, NULL);
+
+      for (source = schema_sources; source; source = source->next)
+        {
+          list = gvdb_table_list (source->data, "");
+
+          if (list)
+            {
+              for (i = 0; list[i]; i++)
+                g_hash_table_insert (builder, list[i], NULL);
+
+              /* not strfreev: we stole the strings into the hashtable */
+              g_free (list);
+            }
+        }
+
+      ptr = list = g_new (gchar *, g_hash_table_size (builder) + 1);
+      g_hash_table_foreach (builder, add_item, &ptr);
+      *ptr = NULL;
+
+      g_hash_table_steal_all (builder);
+      g_hash_table_unref (builder);
+
+      g_once_init_leave (&schema_list, (gsize) list);
+    }
+
+  return (const gchar **) schema_list;
+}
+
 static void
 g_settings_schema_finalize (GObject *object)
 {
@@ -237,28 +299,3 @@ g_settings_schema_list (GSettingsSchema *schema,
   *n_items = schema->priv->n_items;
   return schema->priv->items;
 }
-
-/**
- * g_settings_schema_exists:
- * @schema_name: the schema name to query for
- * Returns: %TRUE if @schema_name exists
- *
- * Checks if the named schema is installed.
- **/
-gboolean
-g_settings_schema_exists (const gchar *schema_name)
-{
-  GSList *source;
-
-  initialise_schema_sources ();
-
-  for (source = schema_sources; source; source = source->next)
-    {
-      GvdbTable *file = source->data;
-
-      if (gvdb_table_get_table (file, schema_name))
-        return TRUE;
-    }
-
-  return FALSE;
-}