libgdm: Fix session loading precedencefix-session-hiding

One feature that GDM is supposed to support is a precedence order
for loading xsession files.

If someone has a file in /etc/X11/sessions it's supposed to override
a file in /usr/share/xsessions.

This works okay from a backend point of view. /etc/X11/sessions can
change the command getting run, for instance, but it doesn't work
from a front end point of view. Menu items can't get hidden in
the session cog.

This is due to a bug in libgdm where it inadvertently gives
/usr/share/xsessions higher precedence than /etc/X11/sessions.

This commit fixes that by processing the lists in reverse order,
and making sure to remove already added entries if overriding
entries are hidden.

1 files changed, 3 insertions, 2 deletions

diff --git a/libgdm/gdm-sessions.c b/libgdm/gdm-sessions.c
index d8b4d5cd..c3aeafdd 100644
--- a/libgdm/gdm-sessions.c
+++ b/libgdm/gdm-sessions.c
@@ -143,6 +143,7 @@ load_session_file (const char              *id,
 
         if (!key_file_is_relevant (key_file)) {
                 g_debug ("\"%s\" is hidden or contains non-executable TryExec program\n", path);
+                g_hash_table_remove (gdm_available_sessions_map, id);
                 goto out;
         }
 
@@ -322,7 +323,7 @@ collect_sessions (void)
         }
 
         if (!supported_session_types || g_strv_contains ((const char * const *) supported_session_types, "x11")) {
-                for (i = 0; i < xorg_search_array->len; i++) {
+                for (i = xorg_search_array->len - 1; i >= 0; i--) {
                         collect_sessions_from_directory (g_ptr_array_index (xorg_search_array, i));
                 }
         }
@@ -330,7 +331,7 @@ collect_sessions (void)
 #ifdef ENABLE_WAYLAND_SUPPORT
 #ifdef ENABLE_USER_DISPLAY_SERVER
         if (!supported_session_types  || g_strv_contains ((const char * const *) supported_session_types, "wayland")) {
-                for (i = 0; i < wayland_search_array->len; i++) {
+                for (i = wayland_search_array->len - 1; i >= 0; i--) {
                         collect_sessions_from_directory (g_ptr_array_index (wayland_search_array, i));
                 }
         }