nixos/davfs2: fix rfc42 conversion, make settings and extraConfig mutually exclusive, and other cleanup

nixos/modules/services/network-filesystems/davfs2.nix

@@ -1,61 +1,72 @@
 { config, lib, pkgs, ... }:
 
-with lib;
-
 let
-  toStr = value:
-    if true == value then "yes"
-    else if false == value then "no"
-    else toString value;
+  inherit (lib.attrsets) optionalAttrs;
+  inherit (lib.generators) toINIWithGlobalSection;
+  inherit (lib.lists) optional;
+  inherit (lib.modules) mkIf;
+  inherit (lib.options) literalExpression mkEnableOption mkOption;
+  inherit (lib.strings) escape;
+  inherit (lib.types) attrsOf bool int lines oneOf str submodule;
 
   cfg = config.services.davfs2;
-  format = pkgs.formats.toml { };
-  configFile = let
-    settings = mapAttrsToList (n: v: "${n} = ${toStr v}") cfg.settings;
-  in pkgs.writeText "davfs2.conf" ''
-    ${concatStringsSep "\n" settings}
-    ${cfg.extraConfig}
-  '';
+
+  escapeString = escape ["\"" "\\"];
+
+  formatValue = value:
+    if true == value then "1"
+    else if false == value then "0"
+    else if builtins.isString value then "\"${escapeString value}\""
+    else toString value;
+
+  configFile = pkgs.writeText "davfs2.conf" (
+    if (cfg.settings != { }) then
+      (toINIWithGlobalSection {
+        mkSectionName = escapeString;
+        mkKeyValue = k: v: "${k} ${formatValue v}";
+      } cfg.settings)
+    else
+      cfg.extraConfig
+  );
 in
 {
 
   options.services.davfs2 = {
-    enable = mkOption {
-      type = types.bool;
-      default = false;
-      description = lib.mdDoc ''
-        Whether to enable davfs2.
-      '';
-    };
+    enable = mkEnableOption "davfs2";
 
     davUser = mkOption {
-      type = types.str;
+      type = str;
       default = "davfs2";
-      description = lib.mdDoc ''
+      description = ''
         When invoked by root the mount.davfs daemon will run as this user.
         Value must be given as name, not as numerical id.
       '';
     };
 
     davGroup = mkOption {
-      type = types.str;
+      type = str;
       default = "davfs2";
-      description = lib.mdDoc ''
+      description = ''
         The group of the running mount.davfs daemon. Ordinary users must be
         member of this group in order to mount a davfs2 file system. Value must
         be given as name, not as numerical id.
       '';
     };
 
     extraConfig = mkOption {
-      type = types.lines;
+      type = lines;
       default = "";
       example = ''
-        kernel_fs coda
         proxy foo.bar:8080
         use_locks 0
+
+        [/media/dav]
+        use_locks 1
+
+        [/home/otto/mywebspace]
+        gui_optimize 1
       '';
-      description = lib.mdDoc ''
+      description = ''
         Extra lines appended to the configuration of davfs2.
         See {manpage}`davfs2.conf(5)` for available settings.
 
@@ -66,18 +77,30 @@ in
     };
 
     settings = mkOption {
-      type = types.submodule {
-        freeformType = format.type;
+      type = submodule {
+        freeformType = let
+          valueTypes = [ bool int str ];
+        in
+        attrsOf (attrsOf (oneOf (valueTypes ++ [ (attrsOf (oneOf valueTypes)) ] )));
       };
-      default = {};
+      default = { };
       example = literalExpression ''
         {
-          kernel_fs = "coda";
-          proxy = "foo.bar:8080";
-          use_locks = 0;
+          globalSection = {
+            proxy = "foo.bar:8080";
+            use_locks = false;
+          };
+          sections = {
+            "/media/dav" = {
+              use_locks = true;
+            };
+            "/home/otto/mywebspace" = {
+              gui_optimize = true;
+            };
+          };
         }
       '';
-      description = lib.mdDoc ''
+      description = ''
         Extra settings appended to the configuration of davfs2.
         See {manpage}`davfs2.conf(5)` for available settings.
       ''  ;
@@ -86,16 +109,29 @@ in
 
   config = mkIf cfg.enable {
 
-    warnings = lib.optional (cfg.extraConfig != null) ''
-      services.davfs2.extraConfig will be deprecated in future releases, please use the settings option now.
+    assertions = [
+      {
+        assertion = cfg.extraConfig != "" -> cfg.settings == { };
+        message = ''
+          services.davfs2.extraConfig and services.davfs2.settings cannot be used together.
+          Please prefer using services.davfs2.settings.
+        '';
+      }
+    ];
+
+    warnings = optional (cfg.extraConfig != "") ''
+      services.davfs2.extraConfig will be deprecated in future releases;
+      please use services.davfs2.settings instead.
     '';
 
     environment.systemPackages = [ pkgs.davfs2 ];
     environment.etc."davfs2/davfs2.conf".source = configFile;
 
     services.davfs2.settings = {
-      dav_user = cfg.davUser;
-      dav_group = cfg.davGroup;
+      globalSection = {
+        dav_user = cfg.davUser;
+        dav_group = cfg.davGroup;
+      };
     };
 
     users.groups = optionalAttrs (cfg.davGroup == "davfs2") {