flake.nix: add freebsd cross compiled variant of package

flake.nix

@@ -20,6 +20,12 @@
       in {
         default = self.packages.${system}.wamf;
         wamf = pkgs.callPackage ./nix/package.nix { inherit src; };
+        wamf-freebsd-cross = let
+          pkgs = import nixpkgs {
+            localSystem = system;
+            crossSystem = "x86_64-freebsd";
+          };
+        in pkgs.callPackage ./nix/package.nix { inherit src; };
       };
     };
 }

nix/package.nix

@@ -3,7 +3,9 @@
   src,
   stdenv,
 }:
-
+let
+  isFreebsdCross = !stdenv.buildPlatform.isFreeBSD && stdenv.hostPlatform.isFreeBSD;
+in
 stdenv.mkDerivation {
   pname = "where-are-my-friends";
   version = "0.1.0";
@@ -14,6 +16,13 @@ stdenv.mkDerivation {
     "CC=${stdenv.cc.targetPrefix}cc"
   ];
 
+  postFixup = lib.optionalString isFreebsdCross ''
+    patchelf --set-interpreter /usr/libexec/ld-elf.so.1 "$out/bin/wamf"
+    patchelf --remove-rpath "$out/bin/wamf"
+  '';
+
+  hardeningDisable = lib.optionals isFreebsdCross [ "fortify" ];
+
   meta = {
     description = "RCON -> Bluemap player position API converter";
     homepage = "https://git.pvv.ntnu.no/Projects/where-are-my-friends";