simplex-chat-desktop: fix updates for aarch64-linux (#518068)

pkgs/by-name/si/simplex-chat-desktop/package.nix

@@ -2,7 +2,6 @@
   lib,
   appimageTools,
   fetchurl,
-  gitUpdater,
   stdenv,
 }:
 
@@ -13,7 +12,7 @@ let
   sources = {
     "aarch64-linux" = fetchurl {
       url = "https://github.com/simplex-chat/simplex-chat/releases/download/v${version}/simplex-desktop-aarch64.AppImage";
-      hash = "sha256-CvHwYKbieRYbBKUCoKAa11rTy5Opdfb7FKS4poantKs=";
+      hash = "sha256-VrPNKXgVO/9yvGqseOVkYKMFVqhtExL2PCJb6stn3ko=";
     };
     "x86_64-linux" = fetchurl {
       url = "https://github.com/simplex-chat/simplex-chat/releases/download/v${version}/simplex-desktop-x86_64.AppImage";
@@ -46,11 +45,9 @@ appimageTools.wrapType2 {
     cp -r ${appimageContents}/usr/share/icons $out/share
   '';
 
-  passthru.updateScript = gitUpdater {
-    url = "https://github.com/simplex-chat/simplex-chat";
-    rev-prefix = "v";
-    # skip tags that does not correspond to official releases, like vX.Y.Z-(beta,fdroid,armv7a).
-    ignoredVersions = "-";
+  passthru = {
+    inherit sources;
+    updateScript = ./update.sh;
   };
 
   meta = {

pkgs/by-name/si/simplex-chat-desktop/update.sh

@@ -0,0 +1,32 @@
+#!/usr/bin/env nix-shell
+#!nix-shell -i bash -p curl jq common-updater-scripts
+
+set -euo pipefail
+
+attr="simplex-chat-desktop"
+
+# Get the latest non-prerelease tag from GitHub.
+latest=$(curl -fsSL ${GITHUB_TOKEN:+" -u \":$GITHUB_TOKEN\""} \
+  "https://api.github.com/repos/simplex-chat/simplex-chat/releases/latest" \
+  | jq -r '.tag_name')
+
+# Strip the leading "v".
+version="${latest#v}"
+
+# Current version in nixpkgs (so we can short-circuit if unchanged).
+current=$(nix-instantiate --eval -E "with import ./. {}; ${attr}.version" \
+  | tr -d '"')
+
+if [[ "$version" == "$current" ]]; then
+  echo "${attr} is already at ${version}"
+  exit 0
+fi
+
+# Update each per-system source independently.
+update-source-version "$attr" "$version" \
+    --source-key=sources.x86_64-linux
+
+# --ignore-same-version flag silences warning because previous invocation bumped version
+update-source-version "$attr" "$version" \
+    --ignore-same-version \
+    --source-key=sources.aarch64-linux