Add modules

modules/user.nix

@@ -0,0 +1,81 @@
+# Licensed under GNU Lesser General Public License v3 or later, see COPYING.
+# Copyright (c) 2019 Alexander Sosedkin and other contributors, see AUTHORS.
+
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.user;
+
+  idsDerivation = pkgs.runCommand "ids.nix" {} ''
+    cat > $out <<EOF
+    {
+      gid = "$(${pkgs.coreutils}/bin/id -g)";
+      uid = "$(${pkgs.coreutils}/bin/id -u)";
+    }
+    EOF
+  '';
+
+  ids = import idsDerivation;
+in
+
+{
+
+  ###### interface
+
+  options = {
+
+    user = {
+      group = mkOption {
+        type = types.str;
+        default = "nix-on-droid";
+        description = "Group name.";
+      };
+
+      home = mkOption {
+        type = types.path;
+        readOnly = true;
+        description = "Path to home directory.";
+      };
+
+      shell = mkOption {
+        type = types.path;
+        readOnly = true;
+        description = "Path to login shell.";
+      };
+
+      userName = mkOption {
+        type = types.str;
+        default = "nix-on-droid";
+        description = "User name.";
+      };
+    };
+
+  };
+
+
+  ###### implementation
+
+  config = {
+
+    environment.etc = {
+      "group".text = ''
+        root:x:0:
+        ${cfg.group}:x:${ids.gid}:${cfg.userName}
+      '';
+
+      "passwd".text = ''
+        root:x:0:0:System administrator:${config.build.installationDir}/root:/bin/sh
+        ${cfg.userName}:x:${ids.uid}:${ids.gid}:${cfg.userName}:${cfg.home}:${cfg.shell}
+      '';
+    };
+
+    user = {
+      home = "/data/data/com.termux.nix/files/home";
+      shell = "/bin/sh";
+    };
+
+  };
+
+}