spidermonkey: add update script

partially based on https://github.com/NixOS/nixpkgs/blob/6f31c2529024d14916da3ea3e84d886ef67d3084/pkgs/applications/networking/browsers/firefox/update.nix. tested with 140.13.0.

pkgs/development/interpreters/spidermonkey/common.nix

@@ -166,11 +166,15 @@ stdenv.mkDerivation (finalAttrs: {
     ln -s $out/bin/js${lib.versions.major version} $out/bin/js
   '';
 
-  passthru.tests.run = callPackage ./test.nix {
-    spidermonkey = finalAttrs.finalPackage;
+  passthru = {
+    tests.run = callPackage ./test.nix {
+      spidermonkey = finalAttrs.finalPackage;
+    };
+    updateScript = lib.getExe (callPackage ./update.nix { version = lib.versions.major version; });
   };
 
   meta = {
+    changelog = "https://www.firefox.com/en-US/firefox/${version}/releasenotes/";
     description = "Mozilla's JavaScript engine written in C/C++";
     homepage = "https://spidermonkey.dev/";
     license = lib.licenses.mpl20;

pkgs/development/interpreters/spidermonkey/update.nix

@@ -0,0 +1,39 @@
+{
+  writeShellApplication,
+  common-updater-scripts,
+  xidel,
+  baseUrl ? "https://archive.mozilla.org/pub/firefox/releases/",
+  version ? "",
+}:
+writeShellApplication {
+  name = "update-spidermonkey_${version}";
+  runtimeInputs = [
+    common-updater-scripts
+    xidel
+  ];
+
+  text = ''
+    set -eux
+
+    HOME=$(mktemp -d)
+    GNUPGHOME=$(mktemp -d)
+    export GNUPGHOME
+
+    curl https://keys.openpgp.org/vks/v1/by-fingerprint/09BEED63F3462A2DFFAB3B875ECB6497C1A20256 | gpg --import -
+
+    version=$(xidel --trace -s "${baseUrl}" --extract "//a" | \
+     grep "^${version}[0-9.]*esr/$" | \
+     sed s/[/]$// | \
+     sort --version-sort | \
+     tail -n 1)
+
+    curl --silent --show-error -o "$HOME"/shasums "${baseUrl}$version/SHA512SUMS"
+    curl --silent --show-error -o "$HOME"/shasums.asc "${baseUrl}$version/SHA512SUMS.asc"
+    gpgv --keyring="$GNUPGHOME"/pubring.kbx "$HOME"/shasums.asc "$HOME"/shasums
+
+    hash=$(grep '\.source\.tar\.xz$' "$HOME"/shasums | grep '^[^ ]*' -o)
+    sri_hash=$(nix hash convert --hash-algo sha512 --to sri "$hash")
+    update-source-version --file=pkgs/development/interpreters/spidermonkey/${version}.nix \
+      "spidermonkey_${version}" "''${version%esr}" "$sri_hash"
+  '';
+}