Use arx instead of makeself.

arx.nix

@@ -0,0 +1,15 @@
+{ stdenv, arx }:
+
+{ name
+, archive
+, startup
+}:
+
+  stdenv.mkDerivation {
+    inherit name;
+    nativeBuildInputs = [ arx ];
+    buildCommand = ''
+      ${arx}/bin/arx tmpx ${archive} -o $out -e ${startup}
+      chmod +x $out
+    '';
+  }

default.nix

@@ -4,12 +4,17 @@ with nixpkgs;
 
 let
 
-  makeself = callPackage ./makeself.nix {};
-  makedir = callPackage ./makedir.nix {};
+  arx = callPackage ./arx.nix {
+    inherit (haskellPackages) arx;
+  };
+
+  maketar = callPackage ./maketar.nix {
+  };
+
   nix-installer = callPackage ./nix-installer.nix {};
 
   makebootstrap = callPackage ./makebootstrap.nix {
-    inherit makedir makeself;
+    inherit arx maketar;
   };
 
   nix-user-chroot = callPackage ./nix-user-chroot.nix {};

makebootstrap.nix

@@ -1,11 +1,10 @@
-{makeself, makedir}:
+{ arx, maketar }:
 
   { name, target, run }:
-    makeself {
+    arx {
       inherit name;
-      startup = ".${target}${run}";
-      archive = makedir {
-        name = "${name}-dir";
-        toplevel = target;
+      startup = "${target}${run}";
+      archive = maketar {
+        inherit name target;
       };
     }

makeself.nix

@@ -1,14 +0,0 @@
-{ stdenv, makeself }:
-
-{ name
-, archive
-, startup
-}:
-
-  stdenv.mkDerivation {
-    inherit name archive startup;
-    nativeBuildInputs = [ makeself ];
-    buildCommand = ''
-      ${makeself}/bin/makeself --xz $archive $out $name $startup
-    '';
-  }

maketar.nix

@@ -1,17 +1,17 @@
 { stdenv, perl, pathsFromGraph }:
 
-{ name, toplevel }:
+{ name, target }:
 
   stdenv.mkDerivation {
-    inherit toplevel name;
-    exportReferencesGraph = [ "closure" toplevel ];
+    inherit name;
+    exportReferencesGraph = [ "closure" target ];
     nativeBuildInputs = [ perl ];
     buildCommand = ''
-      mkdir -p $out
       storePaths=$(${perl}/bin/perl ${pathsFromGraph} ./closure)
-      printRegistration=1 ${perl}/bin/perl ${pathsFromGraph} ./closure > $out/.reginfo
-      for path in $storePaths; do
-        cp --parents -rp $path $out/
-      done
+      printRegistration=1 ${perl}/bin/perl ${pathsFromGraph} ./closure > .reginfo
+      tar cvfj $out \
+        --owner=0 --group=0 --mode=u+rw,uga+r \
+        --hard-dereference \
+        .reginfo $storePaths
     '';
   }