refactor file & symlink

The new system works by adding a file attribute (user.nix-minecraft-managed) to managed files and symlinks. This makes it possible to correctly cleanup managed files (when stopping, restarting, reloading).

I've also added support for directories (Infinidoge#73), and ensured only non-binary files are substituted with env vars (Infinidoge#70)

modules/minecraft-servers.nix

@@ -52,6 +52,13 @@ let
     "ini" = ini { };
   };
 
+  isManaged = file: ''
+    [ "$(${pkgs.attr}/bin/getfattr --no-dereference -n user.nix-minecraft-managed --only-values "${file}" 2>/dev/null)" = "1" ]
+  '';
+  markManaged = file: ''
+    ${pkgs.attr}/bin/setfattr --no-dereference -n user.nix-minecraft-managed -v 1 "${file}"
+  '';
+
   configType = types.submodule {
     options = {
       format = mkOption {
@@ -604,37 +611,48 @@ in
 
             ExecStartPre =
               let
+                clean = file: ''
+                  # If destination already exists
+                  if [[ -e "${file}" ]]; then
+                    # If it's managed by us, delete it. Else, backup it.
+                    if ${isManaged file}; then
+                      rm -rf "${n}"
+                    else
+                      echo "${file} already exists, moving"
+                      mv "${file}" "${file}.bak"
+                    fi
+                  fi
+                '';
                 mkSymlinks = concatStringsSep "\n"
                   (mapAttrsToList
                     (n: v: ''
-                      if [[ -L "${n}" ]]; then
-                        unlink "${n}"
-                      elif [[ -e "${n}" ]]; then
-                        echo "${n} already exists, moving"
-                        mv "${n}" "${n}.bak"
-                      fi
+                      ${clean n}
                       mkdir -p "$(dirname "${n}")"
+
                       ln -sf "${v}" "${n}"
+
+                      ${markManaged n}
                     '')
                     symlinks);
 
                 mkFiles = concatStringsSep "\n"
                   (mapAttrsToList
                     (n: v: ''
-                      if [[ -L "${n}" ]]; then
-                        unlink "${n}"
-                      elif ${pkgs.diffutils}/bin/cmp -s "${n}" "${v}"; then
-                        rm "${n}"
-                      elif [[ -e "${n}" ]]; then
-                        echo "${n} already exists, moving"
-                        mv "${n}" "${n}.bak"
-                      fi
+                      ${clean n}
                       mkdir -p "$(dirname "${n}")"
-                      ${pkgs.gawk}/bin/awk '{
-                        for(varname in ENVIRON)
-                          gsub("@"varname"@", ENVIRON[varname])
-                        print
-                      }' "${v}" > "${n}"
+
+                      # If it's not a binary, substitute env vars. Else, copy it normally
+                      if file --mime-encoding "${v}" | grep -v '\bbinary$'; then
+                        ${pkgs.gawk}/bin/awk '{
+                          for(varname in ENVIRON)
+                            gsub("@"varname"@", ENVIRON[varname])
+                          print
+                        }' "${v}" > "${n}"
+                      else
+                        cp -r --dereference "${v}" -T "${n}"
+                      fi
+
+                      ${markManaged n}
                     '')
                     files);
               in
@@ -674,16 +692,15 @@ in
 
             ExecStopPost =
               let
-                rmSymlinks = concatStringsSep "\n"
-                  (mapAttrsToList (n: v: "unlink \"${n}\"") symlinks);
-                rmFiles = concatStringsSep "\n"
-                  (mapAttrsToList (n: v: "rm -f \"${n}\"") files);
+                # Clean all managed files/symlinks
+                cleanup = ''
+                  ${pkgs.findutils}/bin/find . -exec sh -c '${isManaged}' find-sh {} \; -exec rm -rf "{}" \;
+                '';
               in
               getExe (pkgs.writeShellApplication {
                 name = "minecraft-server-${name}-stop-post";
                 text = ''
-                  ${rmSymlinks}
-                  ${rmFiles}
+                  ${cleanup}
                   ${conf.extraStopPost}
                 '';
               });