signal-cli: Add update script

pkgs/by-name/si/signal-cli/package.nix

@@ -11,6 +11,9 @@
   callPackage,
   versionCheckHook,
   signal-cli,
+  writeShellApplication,
+  curl,
+  nix-update,
 }:
 
 let
@@ -93,6 +96,21 @@ stdenv.mkDerivation (finalAttrs: {
 
   nativeInstallCheckInputs = [ versionCheckHook ];
 
+  passthru = {
+    updateScript = lib.getExe (writeShellApplication {
+      name = "signal-cli-update";
+      runtimeInputs = [
+        curl
+        nix-update
+      ];
+      text = ''
+        nix-update signal-cli
+        nix-update signal-cli.passthru.libsignal-jni --version "$(curl --silent --location https://github.com/AsamK/signal-cli/raw/v"$(nix-instantiate --raw --eval -A signal-cli.version)"/libsignal-version)"
+      '';
+    });
+    libsignal-jni = libsignal-jni;
+  };
+
   meta = {
     homepage = "https://github.com/AsamK/signal-cli";
     description = "Command-line and dbus interface for communicating with the Signal messaging service";