x11: Add method to launch applications, using SnLauncher

The method spawns a launch request that will get caught by the
SnMonitor we have in place to handle X11 startup notification
messages.

src/x11/meta-startup-notification-x11.c

@@ -19,6 +19,8 @@
 #include "config.h"
 #include "meta-startup-notification-x11.h"
 
+#include <gio/gdesktopappinfo.h>
+
 #include "core/display-private.h"
 #include "core/startup-notification-private.h"
 #include "meta/meta-x11-errors.h"
@@ -296,3 +298,72 @@ meta_x11_startup_notification_handle_xevent (MetaX11Display *x11_display,
 
   return sn_display_process_event (x11_sn->sn_display, xevent);
 }
+
+typedef void (* SetAppIdFunc) (SnLauncherContext *context,
+                               const char        *app_id);
+
+gchar *
+meta_x11_startup_notification_launch (MetaX11Display *x11_display,
+                                      GAppInfo       *app_info,
+                                      uint32_t        timestamp,
+                                      int             workspace)
+{
+  gchar *startup_id = NULL;
+#ifdef HAVE_STARTUP_NOTIFICATION
+  MetaX11StartupNotification *x11_sn = x11_display->startup_notification;
+  SnLauncherContext *sn_launcher;
+  int screen;
+
+  screen = meta_x11_display_get_screen_number (x11_display);
+  sn_launcher = sn_launcher_context_new (x11_sn->sn_display, screen);
+
+  sn_launcher_context_set_name (sn_launcher, g_app_info_get_name (app_info));
+  sn_launcher_context_set_workspace (sn_launcher, workspace);
+  sn_launcher_context_set_binary_name (sn_launcher,
+                                       g_app_info_get_executable (app_info));
+
+  if (G_IS_DESKTOP_APP_INFO (app_info))
+    {
+      const char *application_id;
+      SetAppIdFunc func = NULL;
+      GModule *self;
+
+      application_id =
+        g_desktop_app_info_get_filename (G_DESKTOP_APP_INFO (app_info));
+      self = g_module_open (NULL, G_MODULE_BIND_MASK);
+
+      /* This here is a terrible workaround to bypass a libsn bug that is not
+       * likely to get fixed at this point.
+       * sn_launcher_context_set_application_id is correctly defined in the
+       * sn-launcher.h file, but it's mistakenly called
+       * sn_launcher_set_application_id in the C file.
+       *
+       * We look up the symbol instead, but still prefer the correctly named
+       * function, if one were ever to be added.
+       */
+      if (!g_module_symbol (self, "sn_launcher_context_set_application_id",
+                            (gpointer *) &func))
+        {
+          g_module_symbol (self, "sn_launcher_set_application_id",
+                           (gpointer *) &func);
+        }
+
+      if (func)
+        func (sn_launcher, application_id);
+
+      g_module_close (self);
+    }
+
+  sn_launcher_context_initiate (sn_launcher,
+                                g_get_prgname (),
+                                g_app_info_get_name (app_info),
+                                timestamp);
+
+  startup_id = g_strdup (sn_launcher_context_get_startup_id (sn_launcher));
+
+  /* Fire and forget, we have a SnMonitor in addition */
+  sn_launcher_context_unref (sn_launcher);
+#endif /* HAVE_STARTUP_NOTIFICATION */
+
+  return startup_id;
+}

src/x11/meta-startup-notification-x11.h

@@ -36,4 +36,9 @@ void     meta_x11_startup_notification_release (MetaX11Display *x11_display);
 gboolean meta_x11_startup_notification_handle_xevent (MetaX11Display *x11_display,
                                                       XEvent         *xevent);
 
+gchar *  meta_x11_startup_notification_launch (MetaX11Display *x11_display,
+                                               GAppInfo       *app_info,
+                                               uint32_t        timestamp,
+                                               int             workspace);
+
 #endif /* META_X11_STARTUP_NOTIFICATION_H */