Use spawn_async instead of spawn_sync

The 'spawn_sync' function has been deprecated for a very long time now,
but we could never use its intended replacement as its Vala bindings
were broken [1]. The underlying problem had been identified in [2] a
while ago, but has only been recently fixed in [3] and is now available
in Vala's 0.56 branch.

Since we rely on the child PID as a fallback for opinionated users or
shells that are unaware of OSC 7, we have to pass a callback function to
the 'spawn_async' call so we can capture the PID which is no longer
supplied by the method itself.

[1] https://gitlab.gnome.org/GNOME/vte/issues/227
[2] https://gitlab.gnome.org/GNOME/vala/-/issues/721
[3] https://gitlab.gnome.org/GNOME/vala/-/commit/f058e9e828f494ebf8d60cabff7999f219048623

2 files changed, 17 insertions, 14 deletions

diff --git a/TODO b/TODO
index 5f45578..de89335 100644
--- a/TODO
+++ b/TODO
@@ -7,13 +7,6 @@
 
   [1] https://developer.gnome.org/gtk3/stable/GtkImageMenuItem.html#gtk-image-menu-item-new
 
-- Upstream recommends spawn_async() instead of spawn_sync(), but the bindings
-  for it are erroneous.
-
-  See: https://gitlab.gnome.org/GNOME/vala/issues/721
-       https://gitlab.gnome.org/GNOME/gobject-introspection/merge_requests/168
-       https://gitlab.gnome.org/GNOME/vte/issues/227
-
 - The upstream GTK devel branch has dropped some X11-specific APIs, including
   the interface for urgency hints. Eventually, this feature will have to be
   removed from weltschmerz too.
diff --git a/terminal.vala b/terminal.vala
index e2c8d48..67256d4 100644
--- a/terminal.vala
+++ b/terminal.vala
@@ -80,16 +80,26 @@ class Terminal : Gtk.Overlay {
 			var regex = new Vte.Regex.for_match(URL_REGEX, URL_REGEX.length, PCRE2_CASELESS | PCRE2_MULTILINE);
 			vte.match_add_regex(regex, 0);
 			vte.match_set_cursor_name(0, "pointer");
-
-			var argv = args[1:args.length];
-			if (argv.length == 0) {
-				argv = { Utils.get_shell() };
-			}
-
-			vte.spawn_sync(DEFAULT, null, argv, null, SEARCH_PATH, null, out child_pid, null);
 		} catch (Error e) {
 			error(e.message);
 		}
+
+		var argv = args[1:args.length];
+		if (argv.length == 0) {
+			argv = { Utils.get_shell() };
+		}
+
+		Vte.TerminalSpawnAsyncCallback callback = this.spawn_terminal_callback;
+		vte.spawn_async(DEFAULT, null, argv, null, SEARCH_PATH, null, -1, null, callback);
+	}
+
+	void spawn_terminal_callback(Vte.Terminal terminal, Pid pid, Error? error) {
+		if (error != null) {
+			print("weltschmerz: %s\n".printf(error.message));
+			Process.exit(1);
+		}
+
+		this.child_pid = pid;
 	}
 
 	Gtk.PolicyType get_scrollbar_policy(bool want_scrollbar) {