app-list: Use double-fork spawn

cosmic-app-list/src/app.rs

@@ -785,7 +785,7 @@ impl cosmic::Application for CosmicAppList {
                     WaylandUpdate::ActivationToken { token, exec } => {
                         let mut exec = shlex::Shlex::new(&exec);
                         let mut cmd = match exec.next() {
-                            Some(cmd) if !cmd.contains('=') => tokio::process::Command::new(cmd),
+                            Some(cmd) if !cmd.contains('=') => std::process::Command::new(cmd),
                             _ => return Command::none(),
                         };
                         for arg in exec {
@@ -798,7 +798,9 @@ impl cosmic::Application for CosmicAppList {
                             cmd.env("XDG_ACTIVATION_TOKEN", &token);
                             cmd.env("DESKTOP_STARTUP_ID", &token);
                         }
-                        let _ = cmd.spawn();
+                        tokio::task::spawn_blocking(|| {
+                            crate::process::spawn(cmd);
+                        });
                     }
                 }
             }

cosmic-app-list/src/main.rs

@@ -2,6 +2,7 @@
 mod app;
 mod config;
 mod localize;
+mod process;
 mod wayland_handler;
 mod wayland_subscription;
 

cosmic-app-list/src/process.rs

@@ -0,0 +1,31 @@
+use std::process::{exit, Command, Stdio};
+
+use nix::sys::wait::waitpid;
+use nix::unistd::{fork, ForkResult};
+
+/// Performs a double fork with setsid to spawn and detach a command.
+pub fn spawn(mut command: Command) {
+    command
+        .stdin(Stdio::null())
+        .stdout(Stdio::null())
+        .stderr(Stdio::null());
+
+    unsafe {
+        match fork() {
+            Ok(ForkResult::Parent { child }) => {
+                let _res = waitpid(Some(child), None);
+            }
+
+            Ok(ForkResult::Child) => {
+                let _res = nix::unistd::setsid();
+                let _res = command.spawn();
+
+                exit(0);
+            }
+
+            Err(why) => {
+                println!("failed to fork and spawn command: {}", why.desc());
+            }
+        }
+    }
+}