[mutter] monitor-config: Allow loading from a system file

[Jasper St. Pierre <jstpierre src gnome org>]

commit 0f8e387dc08c4055a83a1c2bc7b7f3f2ed5e7393
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Mon Apr 27 16:18:26 2015 -0700

    monitor-config: Allow loading from a system file

 src/backends/meta-monitor-config.c |   37 +++++++++++++++++++++++++++--------
 1 files changed, 28 insertions(+), 9 deletions(-)
---
diff --git a/src/backends/meta-monitor-config.c b/src/backends/meta-monitor-config.c
index 835caa4..6cc42fd 100644
--- a/src/backends/meta-monitor-config.c
+++ b/src/backends/meta-monitor-config.c
@@ -82,7 +82,8 @@ struct _MetaMonitorConfig {
   gboolean current_is_for_laptop_lid;
   MetaConfiguration *previous;
 
-  GFile *file;
+  GFile *user_file;
+  GFile *system_file;
   GCancellable *save_cancellable;
 
   UpClient *up_client;
@@ -238,6 +239,7 @@ meta_monitor_config_init (MetaMonitorConfig *self)
 {
   const char *filename;
   char *path;
+  const char * const *system_dirs;
 
   self->configs = g_hash_table_new_full (config_hash, config_equal, NULL, (GDestroyNotify) config_unref);
 
@@ -246,9 +248,17 @@ meta_monitor_config_init (MetaMonitorConfig *self)
     filename = "monitors.xml";
 
   path = g_build_filename (g_get_user_config_dir (), filename, NULL);
-  self->file = g_file_new_for_path (path);
+  self->user_file = g_file_new_for_path (path);
   g_free (path);
 
+  for (system_dirs = g_get_system_config_dirs (); !self->system_file && *system_dirs; system_dirs++)
+    {
+      path = g_build_filename (*system_dirs, filename, NULL);
+      if (g_file_test (path, G_FILE_TEST_EXISTS))
+        self->system_file = g_file_new_for_path (path);
+      g_free (path);
+    }
+
   self->up_client = up_client_new ();
   self->lid_is_closed = up_client_get_lid_is_closed (self->up_client);
 
@@ -717,8 +727,8 @@ static const GMarkupParser config_parser = {
   .text = handle_text,
 };
 
-static void
-meta_monitor_config_load (MetaMonitorConfig  *self)
+static gboolean
+load_config_file (MetaMonitorConfig *self, GFile *file)
 {
   char *contents;
   gsize size;
@@ -736,14 +746,12 @@ meta_monitor_config_load (MetaMonitorConfig  *self)
   */
 
   error = NULL;
-  ok = g_file_load_contents (self->file, NULL, &contents, &size, NULL, &error);
+  ok = g_file_load_contents (file, NULL, &contents, &size, NULL, &error);
   if (!ok)
     {
-      if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND))
-        meta_warning ("Failed to load stored monitor configuration: %s\n", error->message);
 
       g_error_free (error);
-      return;
+      return FALSE;
     }
 
   memset (&parser, 0, sizeof (ConfigParser));
@@ -772,6 +780,17 @@ meta_monitor_config_load (MetaMonitorConfig  *self)
 
   g_markup_parse_context_free (context);
   g_free (contents);
+
+  return ok;
+}
+
+static void
+meta_monitor_config_load (MetaMonitorConfig *self)
+{
+  if (self->user_file && load_config_file (self, self->user_file))
+    return;
+  if (self->system_file && load_config_file (self, self->system_file))
+    return;
 }
 
 MetaMonitorConfig *
@@ -1622,7 +1641,7 @@ meta_monitor_config_save (MetaMonitorConfig *self)
   closure->config = g_object_ref (self);
   closure->buffer = buffer;
 
-  g_file_replace_contents_async (self->file,
+  g_file_replace_contents_async (self->user_file,
                                  buffer->str, buffer->len,
                                  NULL, /* etag */
                                  TRUE,