[glib] gapplication: add a way to override the app-id

[Matthias Clasen <matthiasc src gnome org>]

commit b32f8ba19bd05db95f65baa5074c942b3964c1d3
Author: Lars Uebernickel <lars uebernickel canonical com>
Date:   Tue Feb 3 14:09:44 2015 +0100

    gapplication: add a way to override the app-id
    
    Some applications support running in a mode where they present
    themselves as a different application to the user (for example web
    browsers or terminals).
    
    To facilitate this, add an option --gapplication-app-id which allows
    users to override an application's id from desktop files or similar.
    
    Applications need to opt-in to this by setting the
    G_APPLICATION_CAN_OVERRIDE_APP_ID flag.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=743933

 gio/gapplication.c |   32 +++++++++++++++++++++++++-------
 gio/gioenums.h     |    7 ++++++-
 2 files changed, 31 insertions(+), 8 deletions(-)
---
diff --git a/gio/gapplication.c b/gio/gapplication.c
index 7a2cbb5..3151342 100644
--- a/gio/gapplication.c
+++ b/gio/gapplication.c
@@ -474,8 +474,10 @@ g_application_parse_command_line (GApplication   *application,
                                   GError        **error)
 {
   gboolean become_service = FALSE;
+  gchar *app_id = NULL;
   GVariantDict *dict = NULL;
   GOptionContext *context;
+  GOptionGroup *gapplication_group;
 
   /* Due to the memory management of GOptionGroup we can only parse
    * options once.  That's because once you add a group to the
@@ -487,6 +489,12 @@ g_application_parse_command_line (GApplication   *application,
 
   context = g_option_context_new (NULL);
 
+  gapplication_group = g_option_group_new ("gapplication",
+                                           _("GApplication options"), _("Show GApplication options"),
+                                           NULL, NULL);
+  g_option_group_set_translation_domain (gapplication_group, GETTEXT_PACKAGE);
+  g_option_context_add_group (context, gapplication_group);
+
   /* If the application has not registered local options and it has
    * G_APPLICATION_HANDLES_COMMAND_LINE then we have to assume that
    * their primary instance commandline handler may want to deal with
@@ -525,20 +533,25 @@ g_application_parse_command_line (GApplication   *application,
    */
   if ((application->priv->flags & (G_APPLICATION_IS_SERVICE | G_APPLICATION_IS_LAUNCHER)) == 0)
     {
-      GOptionGroup *option_group;
       GOptionEntry entries[] = {
         { "gapplication-service", '\0', 0, G_OPTION_ARG_NONE, &become_service,
           N_("Enter GApplication service mode (use from D-Bus service files)") },
         { NULL }
       };
 
-      option_group = g_option_group_new ("gapplication",
-                                         _("GApplication options"), _("Show GApplication options"),
-                                         NULL, NULL);
-      g_option_group_set_translation_domain (option_group, GETTEXT_PACKAGE);
-      g_option_group_add_entries (option_group, entries);
+      g_option_group_add_entries (gapplication_group, entries);
+    }
+
+  /* Allow overriding the ID if the application allows it */
+  if (application->priv->flags & G_APPLICATION_CAN_OVERRIDE_APP_ID)
+    {
+      GOptionEntry entries[] = {
+        { "gapplication-app-id", '\0', 0, G_OPTION_ARG_STRING, &app_id,
+          N_("Override the application's ID") },
+        { NULL }
+      };
 
-      g_option_context_add_group (context, option_group);
+      g_option_group_add_entries (gapplication_group, entries);
     }
 
   /* Now we parse... */
@@ -549,6 +562,10 @@ g_application_parse_command_line (GApplication   *application,
   if (become_service)
     application->priv->flags |= G_APPLICATION_IS_SERVICE;
 
+  /* Check for --gapplication-app-id */
+  if (app_id)
+    g_application_set_application_id (application, app_id);
+
   dict = g_variant_dict_new (NULL);
   if (application->priv->packed_options)
     {
@@ -562,6 +579,7 @@ out:
   application->priv->options_parsed = TRUE;
 
   g_option_context_free (context);
+  g_free (app_id);
 
   return dict;
 }
diff --git a/gio/gioenums.h b/gio/gioenums.h
index 163d635..4461f83 100644
--- a/gio/gioenums.h
+++ b/gio/gioenums.h
@@ -1464,6 +1464,9 @@ typedef enum
  *     owner of the application ID nor does it check if an existing
  *     owner already exists.  Everything occurs in the local process.
  *     Since: 2.30.
+ * @G_APPLICATION_CAN_OVERRIDE_APP_ID: Allow users to override the
+ *     application ID from the command line with `--gapplication-app-id`.
+ *     Since: 2.48
  *
  * Flags used to define the behaviour of a #GApplication.
  *
@@ -1479,7 +1482,9 @@ typedef enum
   G_APPLICATION_HANDLES_COMMAND_LINE = (1 << 3),
   G_APPLICATION_SEND_ENVIRONMENT    =  (1 << 4),
 
-  G_APPLICATION_NON_UNIQUE =           (1 << 5)
+  G_APPLICATION_NON_UNIQUE =           (1 << 5),
+
+  G_APPLICATION_CAN_OVERRIDE_APP_ID =  (1 << 6)
 } GApplicationFlags;
 
 /**