[gnome-session/benzea/autostart-whitelist: 1/2] fill: Add AutostartWhitelist key to session file

[Benjamin Berg <bberg src gnome org>]

commit 2f3b342133e31b8e30bf10833d1a0732c0477abb
Author: Benjamin Berg <bberg redhat com>
Date:   Tue Apr 7 16:27:03 2020 +0200

    fill: Add AutostartWhitelist key to session file
    
    gnome-session currently has an autostart directory override. The purpose
    of this is to disable the usual autostart applications and only start
    whatever is in the given autostart directory.
    
    The nice thing about this is that it is possible (even for third
    parties) to extend the autostart list. The bad part is that it is an odd
    mechanism of partially disabling autostart. One that cannot be mapped
    appropriately to e.g. a systemd generator.
    
    To improve this, add a new AutostartWhitelist key. This key effecitvely
    disables autostart (if left empty) and one can add a whitelist of
    applications that should still be started (in the login screen, as that
    is the only real user).
    
    The disadvantage is that it means distributions need to e.g. add
    spice-vdagent uconditionally to this list rather than installing it into
    /usr/share/gdm/greeter/autostart. The advantage is that the key can be
    appropriately resolved without passing any magic parameters or
    environment variables over from GDM to the gnome-session. It also means
    that quite a bit of code can be removed from gnome-session.

 gnome-session/gsm-manager.c      | 11 ++++++++++-
 gnome-session/gsm-manager.h      |  5 +++--
 gnome-session/gsm-session-fill.c | 14 +++++++++++---
 3 files changed, 24 insertions(+), 6 deletions(-)
---
diff --git a/gnome-session/gsm-manager.c b/gnome-session/gsm-manager.c
index 6839a02d..44a0a9d2 100644
--- a/gnome-session/gsm-manager.c
+++ b/gnome-session/gsm-manager.c
@@ -3759,7 +3759,8 @@ gsm_manager_add_required_app (GsmManager *manager,
 
 gboolean
 gsm_manager_add_autostart_apps_from_dir (GsmManager *manager,
-                                         const char *path)
+                                         const char *path,
+                                         const char * const *whitelist)
 {
         GDir       *dir;
         const char *name;
@@ -3776,11 +3777,19 @@ gsm_manager_add_autostart_apps_from_dir (GsmManager *manager,
 
         while ((name = g_dir_read_name (dir))) {
                 char *desktop_file;
+                g_autofree char *app_id = NULL;
 
                 if (!g_str_has_suffix (name, ".desktop")) {
                         continue;
                 }
 
+                if (whitelist) {
+                        /* Remove .desktop suffix */
+                        app_id = g_strndup (name, strlen(name) - 8);
+                        if (!g_strv_contains (whitelist, app_id))
+                                continue;
+                }
+
                 desktop_file = g_build_filename (path, name, NULL);
                 gsm_manager_add_autostart_app (manager, desktop_file, NULL);
                 g_free (desktop_file);
diff --git a/gnome-session/gsm-manager.h b/gnome-session/gsm-manager.h
index 3ce4350f..6f8427c2 100644
--- a/gnome-session/gsm-manager.h
+++ b/gnome-session/gsm-manager.h
@@ -109,8 +109,9 @@ gboolean            gsm_manager_add_autostart_app              (GsmManager     *
 gboolean            gsm_manager_add_required_app               (GsmManager     *manager,
                                                                 const char     *path,
                                                                 const char     *provides);
-gboolean            gsm_manager_add_autostart_apps_from_dir    (GsmManager     *manager,
-                                                                const char     *path);
+gboolean            gsm_manager_add_autostart_apps_from_dir    (GsmManager         *manager,
+                                                                const char         *path,
+                                                                const char * const *whitelist);
 gboolean            gsm_manager_add_legacy_session_apps        (GsmManager     *manager,
                                                                 const char     *path);
 
diff --git a/gnome-session/gsm-session-fill.c b/gnome-session/gsm-session-fill.c
index bdd92081..7a2622c6 100644
--- a/gnome-session/gsm-session-fill.c
+++ b/gnome-session/gsm-session-fill.c
@@ -30,6 +30,7 @@
 #define GSM_KEYFILE_RUNNABLE_KEY "IsRunnableHelper"
 #define GSM_KEYFILE_FALLBACK_KEY "FallbackSession"
 #define GSM_KEYFILE_REQUIRED_COMPONENTS_KEY "RequiredComponents"
+#define GSM_KEYFILE_AUTOSTART_WHITELIST_KEY "AutostartWhitelist"
 
 /* See https://bugzilla.gnome.org/show_bug.cgi?id=641992 for discussion */
 #define GSM_RUNNABLE_HELPER_TIMEOUT 3000 /* ms */
@@ -111,7 +112,7 @@ maybe_load_saved_session_apps (GsmManager *manager)
         if (is_login)
                 return;
 
-        gsm_manager_add_autostart_apps_from_dir (manager, gsm_util_get_saved_session_dir ());
+        gsm_manager_add_autostart_apps_from_dir (manager, gsm_util_get_saved_session_dir (), NULL);
 }
 
 static void
@@ -141,17 +142,24 @@ load_standard_apps (GsmManager *manager,
         g_debug ("fill: *** Done adding required components");
 
         if (!gsm_manager_get_failsafe (manager)) {
+                g_auto(GStrv) autostart_whitelist = NULL;
                 char **autostart_dirs;
                 int    i;
 
                 autostart_dirs = gsm_util_get_autostart_dirs ();
 
-                if (!gsm_manager_get_systemd_managed (manager))
+                autostart_whitelist = g_key_file_get_string_list (keyfile,
+                                                                  GSM_KEYFILE_SESSION_GROUP,
+                                                                  GSM_KEYFILE_AUTOSTART_WHITELIST_KEY,
+                                                                  NULL, NULL);
+
+                if (!gsm_manager_get_systemd_managed (manager) && !autostart_whitelist)
                         maybe_load_saved_session_apps (manager);
 
                 for (i = 0; autostart_dirs[i]; i++) {
                         gsm_manager_add_autostart_apps_from_dir (manager,
-                                                                 autostart_dirs[i]);
+                                                                 autostart_dirs[i],
+                                                                 (const char * const *)autostart_whitelist);
                 }
 
                 g_strfreev (autostart_dirs);