add ability to pass settings to retroarch

pkgs/overlay.nix

@@ -35,4 +35,7 @@ final: prev: {
       '';
 
   roms = final.callPackage ./roms {};
+
+  wrapRetroarch' = { retroarch, cores ? [ ], settings ? { } }:
+    final.callPackage ./wrap-retroarch.nix { inherit retroarch cores settings; };
 }

pkgs/roms/atetris.nix

@@ -1,8 +1,10 @@
-{mkRetroarchRom}:
+{mkRetroarchRom, settings ? {}}:
 mkRetroarchRom {
   name = "atetris";
   src = ./bin/atetris;
 
+  inherit settings;
+
   emulator = "";
   filename = "atetris.zip";
 

pkgs/roms/build/mkRetroarchRom.nix

@@ -1,15 +1,17 @@
-{ mkRom , retroarchFull }:
+{ mkRom , lib, symlinkJoin, libretro, stdenv, retroarchBare, retroarchFull, wrapRetroarch' }:
 { name
 , src
 , emulator
 , filename
-, settings ? {}
+, settings
 , meta
 }:
 let
-  retroarch = retroarchFull.override (prev: {
+  retroarch = wrapRetroarch' {
-    settings = prev.settings // settings;
+    retroarch = retroarchBare;
-  });
+    cores = retroarchFull.cores;
+    inherit settings;
+  };
 in
 mkRom ({
   runtimeInputs = [ retroarch ];

pkgs/roms/dkong.nix

@@ -1,8 +1,10 @@
-{mkRetroarchRom}:
+{mkRetroarchRom, settings ? {}}:
 mkRetroarchRom {
   name = "dkong";
   src = ./bin/dkong;
 
+  inherit settings;
+
   emulator = "fbneo";
   filename = "dkong.zip";
 

pkgs/roms/mario.nix

@@ -1,8 +1,10 @@
-{mkRetroarchRom}:
+{mkRetroarchRom, settings ? {}}:
 mkRetroarchRom {
   name = "mario";
   src = ./bin/mario;
 
+  inherit settings;
+
   emulator = "fbneo";
   filename = "mario.zip";
 

pkgs/roms/neopong.nix

@@ -1,8 +1,10 @@
-{mkRetroarchRom}:
+{mkRetroarchRom, settings ? {}}:
 mkRetroarchRom {
   name = "neopong";
   src = ./bin/neopong;
 
+  inherit settings;
+
   emulator = "fbneo";
   filename = "neopong.zip";
 

pkgs/roms/pacman.nix

@@ -1,8 +1,10 @@
-{mkRetroarchRom}:
+{mkRetroarchRom, settings ? {}}:
 mkRetroarchRom {
   name = "pacman";
   src = ./bin/pacman;
 
+  inherit settings;
+
   emulator = "fbneo";
   filename = "pacman.zip";
 

pkgs/roms/spacedx.nix

@@ -1,8 +1,10 @@
-{mkRetroarchRom}:
+{mkRetroarchRom, settings ? {}}:
 mkRetroarchRom {
   name = "spacedx";
   src = ./bin/spacedx;
 
+  inherit settings;
+
   emulator = "fbneo";
   filename = "spacedx.zip";
 

pkgs/wrap-retroarch.nix

@@ -0,0 +1,60 @@
+{ lib
+, stdenv
+, makeWrapper
+, symlinkJoin
+, runCommand
+, retroarch
+, cores ? [ ]
+, settings ? { }
+}:
+
+let
+  settings' = { libretro_directory = coresPath; } // settings;
+  settingsPath = runCommand "declarative-retroarch.cfg"
+    {
+      value = lib.concatStringsSep "\n" (lib.mapAttrsToList (n: v: "${n} = \"${v}\"") settings);
+      passAsFile = [ "value" ];
+    }
+    ''
+      cp "$valuePath" "$out"
+    '';
+  coresPath = let
+    path = assert
+      lib.assertMsg (builtins.length (map (c: c.libretroCore) cores) == 1)
+      "Libretro cores are not under the same paths"; 
+    (builtins.head cores).libretroCore;
+  in
+    symlinkJoin {
+      name = "retroarch-cores";
+      paths = cores;
+    } + path;
+  wrapperArgs = lib.strings.escapeShellArgs [ "--add-flags" "--config=${settingsPath}" ];
+in
+symlinkJoin {
+  name = "retroarch-with-cores-${lib.getVersion retroarch}";
+
+  paths = [ retroarch ];
+
+  nativeBuildInputs = [ makeWrapper ];
+
+  passthru = {
+    inherit cores;
+    unwrapped = retroarch;
+  };
+
+  postBuild = ''
+    # wrap binary to load cores from the proper location(s)
+    wrapProgram $out/bin/retroarch ${wrapperArgs}
+  '';
+
+  meta = with retroarch.meta; {
+    inherit changelog description homepage license maintainers platforms;
+    longDescription = ''
+      RetroArch is the reference frontend for the libretro API.
+    ''
+    + lib.optionalString (cores != [ ]) ''
+      The following cores are included: ${lib.concatStringsSep ", " (map (c: c.core) cores)}
+    '';
+    mainProgram = "retroarch";
+  };
+}