User: hold on to our keyfile

When updating a User object from keyfile, keep reference on the keyfile
object passed in and modify the Daemon not to destroy it.

When saving a User, instead of creating a new keyfile, reuse the one we
stored on the object.

We still record the properties from the User object into the keyfile in
the previous way (and include a modification to clear out the 'User'
group before doing this).

The intention here is to allow other groups stored in the keyfile to be
preserved.  These other groups are likely to correspond to extension
interfaces (which will be introduced in future patches).

An alternative approach would have been to only preserve groups for
extensions that we currently have loaded but this was abandoned as being
excessively brittle since the result of a temporarily missing extension
file would be the destruction of data.

https://bugs.freedesktop.org/show_bug.cgi?id=63733

2 files changed, 13 insertions, 6 deletions

diff --git a/src/daemon.c b/src/daemon.c
index ec5cc82..81dcbde 100644
--- a/src/daemon.c
+++ b/src/daemon.c
@@ -491,7 +491,7 @@ entry_generator_cachedir (GHashTable *users,
                 key_file = g_key_file_new ();
                 if (g_key_file_load_from_file (key_file, filename, 0, NULL))
                         user_update_from_keyfile (user, key_file);
-                g_key_file_free (key_file);
+                g_key_file_unref (key_file);
                 g_free (filename);
         }
 
diff --git a/src/user.c b/src/user.c
index b71ee02..ec11876 100644
--- a/src/user.c
+++ b/src/user.c
@@ -78,6 +78,8 @@ struct User {
 
         Daemon       *daemon;
 
+        GKeyFile     *keyfile;
+
         uid_t         uid;
         gid_t         gid;
         gchar        *user_name;
@@ -360,6 +362,9 @@ user_update_from_keyfile (User     *user,
             }
         }
 
+        g_clear_pointer (&user->keyfile, g_key_file_unref);
+        user->keyfile = g_key_file_ref (keyfile);
+
         g_object_thaw_notify (G_OBJECT (user));
 }
 
@@ -387,6 +392,8 @@ static void
 user_save_to_keyfile (User     *user,
                       GKeyFile *keyfile)
 {
+        g_key_file_remove_group (keyfile, "User", NULL);
+
         if (user->email)
                 g_key_file_set_string (keyfile, "User", "Email", user->email);
 
@@ -412,15 +419,13 @@ static void
 save_extra_data (User *user)
 {
         gchar *filename;
-        GKeyFile *keyfile;
         gchar *data;
         GError *error;
 
-        keyfile = g_key_file_new ();
-        user_save_to_keyfile (user, keyfile);
+        user_save_to_keyfile (user, user->keyfile);
 
         error = NULL;
-        data = g_key_file_to_data (keyfile, NULL, &error);
+        data = g_key_file_to_data (user->keyfile, NULL, &error);
         if (error == NULL) {
                 filename = g_build_filename (USERDIR,
                                              user->user_name,
@@ -433,7 +438,6 @@ save_extra_data (User *user)
                            user->user_name, error->message);
                 g_error_free (error);
         }
-        g_key_file_free (keyfile);
 }
 
 static void
@@ -1816,6 +1820,8 @@ user_finalize (GObject *object)
 
         user = USER (object);
 
+        g_clear_pointer (&user->keyfile, g_key_file_unref);
+
         g_free (user->object_path);
         g_free (user->user_name);
         g_free (user->real_name);
@@ -2034,4 +2040,5 @@ user_init (User *user)
         user->automatic_login = FALSE;
         user->system_account = FALSE;
         user->login_history = NULL;
+        user->keyfile = g_key_file_new ();
 }