pkgs/den-http-get-updater: support providing target hash

pkgs/by-name/de/den-http-get-updater/package.nix

@@ -21,6 +21,8 @@
   #     file: string;
   #     attrpath: string[]'
   #   };
+  #   prefetchHash: string?;
+  #   targetHash: string?;
   # }[]
   #
   prefetchList ? [],
@@ -34,6 +36,8 @@
   contentParser ? "echo \"$newVersion\"",
 
   unpack ? true,
+  hashAlgo ? "sha256",
+  hashFormat ? "sri",
   name ? if unpack then "source" else null,
 }:
 
@@ -48,7 +52,7 @@ let
     );
     assert lib.isAttrs x.prefetchUrlLocation && lib.isString x.prefetchUrlLocation.attrpath or null;
     rec {
-      inherit fileLocation;
+      inherit fileLocation hashAlgo hashFormat;
       mark = builtins.hashString "sha256" x.previousHash;
       markRegexEscape = lib.escapeRegex mark;
       realFileLocation = builtins.toString x.fileLocation or fileLocation;
@@ -123,7 +127,12 @@ writeScript "den-http-get-updater" (''
   prefetchSucceeded=1
   for url in "''${prefetchUrls[@]}"; do
       echo "trying prefetch '$url'...";
-      expectedHash=$(nix-prefetch-url "$url" ${nixUnpack} ${nixName})
+      expectedHash=$(nix-prefetch-url "$url" ${nixUnpack} ${nixName} --type "${hashAlgo}")
+      expectedHash=$(nix --extra-experimental-features "nix-command" hash convert \
+        --hash-algo "${hashAlgo}" \
+        --to "${hashFormat}" \
+        "$expectedHash"
+      )
       if [[ -n $expectedHash ]]; then
           echo "prefetch succeeded!"
           echo "hash: $expectedHash"