feat: use 'chatter +i' to make a file immutable on linux

home/linux/base/immutable-file.nix

@@ -0,0 +1,64 @@
+{ config
+, lib
+, pkgs
+, ...
+}:
+
+##############################################################################################
+#
+#  Provide a option `home.immutable-file`, it works like `home.file` but make the generated file immutable.
+#
+#  Copy from https://github.com/iosmanthus/nixos-config/blob/349917b/modules/immutable-file.nix
+#
+#  this module use the `chattr +i` to make the file immutable, `i` indicates `immutable`, 
+#  it's a i-node flags only works on Linux.
+# 
+#  TODO not used yet, need to test it.
+# 
+##############################################################################################
+
+with lib;
+let
+  cfg = config.home.immutable-file;
+  immutableFileOpts = { ... }: {
+    options = {
+      src = mkOption {
+        type = types.path;
+      };
+      dst = mkOption {
+        type = types.path;
+      };
+    };
+  };
+  mkImmutableFile = pkgs.writeScript "make_immutable_file" ''
+    # $1: dst
+    # $2: src
+    if [ ! -d "$(dirname $1)" ]; then
+      mkdir -p $1
+    fi
+
+    if [ -f $1 ]; then
+        sudo chattr -i $1
+    fi
+
+    sudo cp $2 $1
+    sudo chattr +i $1
+  '';
+in
+{
+  options.home.immutable-file = mkOption {
+    type = with types; attrsOf (submodule immutableFileOpts);
+    default = { };
+  };
+
+  config = mkIf (cfg != { }) {
+    home.activation = mapAttrs'
+      (name: { src, dst }:
+        nameValuePair
+          "make-immutable-${name}"
+          (lib.hm.dag.entryAfter [ "writeBoundary" ] ''
+            ${mkImmutableFile} ${dst} ${src}
+          ''))
+      cfg;
+  };
+}

home/linux/fcitx5/default.nix

@@ -2,8 +2,10 @@
 
   home.file.".config/fcitx5/profile".source = ./profile;
   home.file.".config/fcitx5/profile-bak".source = ./profile; # used for backup
-  # fcitx5 每次切换输入法，就会修改 ~/.config/fcitx5/profile 文件，导致我用 hm 管理的配置被覆盖
-  # 解决方法是通过如下内置，每次 rebuild 前都先删除下 profile 文件
+
+  # every time fcitx5 switch input method, it will modify ~/.config/fcitx5/profile file, 
+  # which will override my config managed by home-manager
+  # so we need to remove it before everytime we rebuild the config
   home.activation.removeExistingFcitx5Profile = lib.hm.dag.entryBefore [ "checkLinkTargets" ] ''
     rm -f "${config.xdg.configHome}/fcitx5/profile"
   '';