[gnome-software] flatpak: Handle failure of a libflatpak function updating permissions

[Richard Hughes <rhughes src gnome org>]

commit ad93551b8661429895b448a1e3766c877c2eac4c
Author: Philip Withnall <withnall endlessm com>
Date:   Thu May 16 14:03:22 2019 +0100

    flatpak: Handle failure of a libflatpak function updating permissions
    
    It’s possible for flatpak_installation_fetch_remote_metadata_sync() to
    fail — if so, g_bytes_get_data(NULL) will be called, which will emit a
    critical warning.
    
    Correctly handle the error from libflatpak.
    
    Signed-off-by: Philip Withnall <withnall endlessm com>

 plugins/flatpak/gs-flatpak.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)
---
diff --git a/plugins/flatpak/gs-flatpak.c b/plugins/flatpak/gs-flatpak.c
index e0668300..63634ada 100644
--- a/plugins/flatpak/gs-flatpak.c
+++ b/plugins/flatpak/gs-flatpak.c
@@ -163,6 +163,7 @@ gs_flatpak_set_update_permissions (GsFlatpak *self, GsApp *app, FlatpakInstalled
        g_autoptr(GBytes) bytes = NULL;
        g_autoptr(GKeyFile) keyfile = NULL;
        GsAppPermissions permissions;
+       g_autoptr(GError) error_local = NULL;
 
        old_bytes = flatpak_installed_ref_load_metadata (FLATPAK_INSTALLED_REF (xref), NULL, NULL);
        old_keyfile = g_key_file_new ();
@@ -175,14 +176,21 @@ gs_flatpak_set_update_permissions (GsFlatpak *self, GsApp *app, FlatpakInstalled
                                                                 gs_app_get_origin (app),
                                                                 FLATPAK_REF (xref),
                                                                 NULL,
-                                                                NULL);
-       keyfile = g_key_file_new ();
-       g_key_file_load_from_data (keyfile,
-                                  g_bytes_get_data (bytes, NULL),
-                                  g_bytes_get_size (bytes),
-                                  0, NULL);
+                                                                &error_local);
+       if (bytes == NULL) {
+               g_debug ("Failed to get metadata for remote ‘%s’: %s",
+                        gs_app_get_origin (app), error_local->message);
+               g_clear_error (&error_local);
+               permissions = GS_APP_PERMISSIONS_UNKNOWN;
+       } else {
+               keyfile = g_key_file_new ();
+               g_key_file_load_from_data (keyfile,
+                                          g_bytes_get_data (bytes, NULL),
+                                          g_bytes_get_size (bytes),
+                                          0, NULL);
 
-       permissions = perms_from_metadata (keyfile) & ~perms_from_metadata (old_keyfile);
+               permissions = perms_from_metadata (keyfile) & ~perms_from_metadata (old_keyfile);
+       }
 
        /* no new permissions set */
        if (permissions == GS_APP_PERMISSIONS_UNKNOWN)