[dconf/wip/override] engine: allow overriding the config directory used by dconf

[Abderrahim Kitouni <akitouni src gnome org>]

commit e8794ddd6107ce7b2acb2b46796309056611cfdc
Author: Abderrahim Kitouni <akitouni gnome org>
Date:   Wed Oct 3 14:05:10 2018 +0100

    engine: allow overriding the config directory used by dconf
    
    This is used by flatpak. This patch is present in all flatpak runtimes and
    was likely originally written by Alexander Larsson.

 engine/dconf-engine-source-user.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
---
diff --git a/engine/dconf-engine-source-user.c b/engine/dconf-engine-source-user.c
index 1657875..b6b8772 100644
--- a/engine/dconf-engine-source-user.c
+++ b/engine/dconf-engine-source-user.c
@@ -39,11 +39,17 @@ dconf_engine_source_user_open_gvdb (const gchar *name)
 {
   GvdbTable *table;
   gchar *filename;
+  const gchar *override;
+
+  override = g_getenv ("DCONF_USER_CONFIG_DIR");
+  if (override == NULL)
+    filename = g_build_filename (g_get_user_config_dir (), "dconf", name, NULL);
+  else
+    filename = g_build_filename (g_get_home_dir (), override, name, NULL);
 
   /* This can fail in the normal case of the user not having any
    * settings.  That's OK and it shouldn't be considered as an error.
    */
-  filename = g_build_filename (g_get_user_config_dir (), "dconf", name, NULL);
   table = gvdb_table_new (filename, FALSE, NULL);
   g_free (filename);