[gnome-software] appstream: Consider each element of a compound XDG_CURRENT_DESKTOP separately

[Iain Lane <iainl src gnome org>]

commit 38c13b376d2fac65678c38e0359b6f7f7e2dffdf
Author: Iain Lane <iain orangesquash org uk>
Date:   Thu Aug 17 18:59:18 2017 +0100

    appstream: Consider each element of a compound XDG_CURRENT_DESKTOP separately
    
    If a distro (or a user) has set XDG_CURRENT_DESKTOP=foo:bar, we will not
    currently consider apps marked with <compulsory_for_desktop>foo</> as
    compulsory for that desktop. The distro would have to create a merge
    file specifying their own set of compulsory applications - most likely
    replicating those specified upstream.
    
    It seems more generally useful to allow derived desktops to inherit
    compulsory applications from their parents to avoid this work. In the
    case where a distro wants to override the compulsory desktops for a
    component, they can supply a replace component to achieve this.
    
    Split XDG_CURRENT_DESKTOP and compare each element against the values
    given in the AppStream. If any of them match, the application is
    compulsory.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=784748

 plugins/core/gs-appstream.c |   27 ++++++++++++++++++++-------
 1 files changed, 20 insertions(+), 7 deletions(-)
---
diff --git a/plugins/core/gs-appstream.c b/plugins/core/gs-appstream.c
index 388a49a..87440c9 100644
--- a/plugins/core/gs-appstream.c
+++ b/plugins/core/gs-appstream.c
@@ -505,6 +505,7 @@ gs_appstream_refine_app (GsPlugin *plugin,
        const gchar *tmp;
        guint i;
        g_autoptr(AsProfileTask) ptask = NULL;
+       g_auto(GStrv) xdg_current_desktops = NULL;
 
        /* search categories for the search term */
        ptask = as_profile_start (gs_plugin_get_profile (plugin),
@@ -681,21 +682,33 @@ gs_appstream_refine_app (GsPlugin *plugin,
 
        /*
         * Set the core applications for the current desktop that cannot be
-        * removed -- but note: XDG_CURRENT_DESKTOP="GNOME" is different to
-        * XDG_CURRENT_DESKTOP="Ubuntu:GNOME" here.
+        * removed.
         *
-        * To define what is compulsory for the hybrid desktop either:
+        * If XDG_CURRENT_DESKTOP contains ":", indicating that it is made up
+        * of multiple comopnents per the Desktop Entry Specification, an app
+        * is compulsory if any of the components in XDG_CURRENT_DESKTOP match
+        * any value in <compulsory_for_desktops />. In that way,
+        * "GNOME-Classic:GNOME" shares compulsory apps with GNOME.
         *
-        *  - Add an appstream merge file downstream with the tag
-        *    <compulsory_for_desktop>Ubuntu:GNOME</compulsory_for_desktop>
+        * As a special case, if the <compulsory_for_desktop /> value contains
+        * a ":", we match the entire XDG_CURRENT_DESKTOP. This lets people set
+        * compulsory apps for such compound desktops if they want.
         *
-        *  - Get upstream projects to add the <compulsory_for_desktop> tag
         */
        array = as_app_get_compulsory_for_desktops (item);
        current_desktop = g_getenv ("XDG_CURRENT_DESKTOP");
+       xdg_current_desktops = g_strsplit (current_desktop, ":", 0);
        for (i = 0; i < array->len; i++) {
                tmp = g_ptr_array_index (array, i);
-               if (g_strcmp0 (current_desktop, tmp) == 0) {
+               /* if the value has a :, check the whole string */
+               if (g_strstr_len (tmp, -1, ":")) {
+                       if (g_strcmp0 (current_desktop, tmp) == 0) {
+                               gs_app_add_quirk (app, AS_APP_QUIRK_COMPULSORY);
+                               break;
+                       }
+               /* otherwise check if any element matches this one */
+               } else if (g_strv_contains ((const gchar * const *) xdg_current_desktops,
+                          tmp)) {
                        gs_app_add_quirk (app, AS_APP_QUIRK_COMPULSORY);
                        break;
                }