app-list: Use double-fork spawn

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());
+            }
+        }
+    }
+}