Rebase PR

modules/nixos/default.nix

@@ -106,6 +106,43 @@ in {
             "${mode} '${file.target}' - - - - ${file.source}"
         ) (filter (f: f.enable && f.source != null) (attrValues files));
       }) (filterAttrs (_: u: (u.enable && u.files != {})) cfg.users);
+      systemd.services = mapAttrs' (name: {files, ...}: {
+        name = "hjem-monitor-" + name;
+        value = {
+          wants = ["systemd-tmpfiles-setup.service" "nix-daemon.socket"];
+          after = ["nix-daemon.socket"];
+          wantedBy = ["multi-user.target"];
+          description = "Monitoring for Hjem files";
+          scriptArgs = "${toString (map (
+            file: file.target
+          ) (filter (f: f.enable && f.source != null) (attrValues files)))}";
+          enableStrictShellChecks = true;
+          script = ''
+            #! ${pkgs.runtimeShell} -e
+            code=0
+            err=""
+            normal=""
+            if test -t 1; then
+              ncolors=$(tput colors)
+              if test -n "$ncolors" && test "$ncolors" -ge 8; then
+                err="$(tput bold)$(tput setaf 3)"
+                normal="$(tput sgr0)"
+              fi
+            fi
+            for var in "$@"
+            do
+              if [ ! -L "$var" ] ; then
+                echo "''${err}$var is not managed by Hjem due to a file conflict, please move or remove the current file.''${normal}"
+                code=1
+              fi
+            done
+            exit $code
+          '';
+          serviceConfig = {
+            Type = "exec";
+          };
+        };
+      }) (filterAttrs (_: u: u.files != {}) config.homes);
     }
 
     (mkIf (cfg.users != {}) {