cups: Use systemd files provided by CUPS

nixos/modules/services/printing/cupsd.nix

@@ -183,10 +183,10 @@ in
     # gets loaded, and then cups cannot access the printers.
     boot.blacklistedKernelModules = [ "usblp" ];
 
-    systemd.services.cups =
+    systemd.packages = [ cups ];
-      { description = "CUPS Printing Daemon";
 
-        wantedBy = [ "multi-user.target" ];
+    systemd.services.cups =
+      { wantedBy = [ "multi-user.target" ];
         wants = [ "network.target" ];
         after = [ "network.target" ];
 
@@ -200,9 +200,6 @@ in
             mkdir -m 0755 -p ${cfg.tempDir}
           '';
 
-        serviceConfig.Type = "forking";
-        serviceConfig.ExecStart = "@${cups}/sbin/cupsd cupsd";
-
         restartTriggers =
           [ config.environment.etc."cups/cups-files.conf".source
             config.environment.etc."cups/cupsd.conf".source

pkgs/misc/cups/default.nix

@@ -58,6 +58,19 @@ stdenv.mkDerivation {
     ''
       # Delete obsolete stuff that conflicts with cups-filters.
       rm -rf $out/share/cups/banners $out/share/cups/data/testprint
+
+      # Rename systemd files provided by CUPS
+      for f in $out/lib/systemd/system/*; do
+        substituteInPlace "$f" \
+          --replace "org.cups.cupsd" "cups" \
+          --replace "org.cups." ""
+
+        if [[ "$f" =~ .*cupsd\..* ]]; then
+          mv "$f" "''${f/org\.cups\.cupsd/cups}"
+        else
+          mv "$f" "''${f/org\.cups\./}"
+        fi
+      done
     '';
 
   meta = {