Update Flatpak (fixes #28)

src/main.rs

@@ -171,6 +171,11 @@ fn run() -> Result<(), Error> {
         run_rustup(&rustup).report("rustup", &mut reports);
     }
 
+    if let Ok(flatpak) = which("flatpak") {
+        terminal.print_separator("Flatpak");
+        run_flatpak(&flatpak).report("Flatpak", &mut reports);
+    }
+
     let cargo_upgrade = home_path(".cargo/bin/cargo-install-update");
     if cargo_upgrade.exists() {
         terminal.print_separator("Cargo");

src/steps.rs

@@ -152,3 +152,13 @@ pub fn run_custom_command(command: &str) -> Result<(), failure::Error> {
 
     Ok(())
 }
+
+pub fn run_flatpak(flatpak: &PathBuf) -> Result<(), failure::Error> {
+    Command::new(&flatpak)
+        .arg("update")
+        .spawn()?
+        .wait()?
+        .check()?;
+
+    Ok(())
+}