Displaylink patch for NixOS

displaylink-udev-installer.patch

--- a/udev-installer.sh	2018-12-09 12:05:53.772318942 +0100
+++ b/udev-installer.sh	2018-12-09 12:06:19.939947629 +0100
@@ -24,12 +24,12 @@ systemd_start_stop_functions()
   cat <<'EOF'
 start_service()
 {
-  systemctl start displaylink-driver
+  @systemd@/bin/systemctl start --no-block dlm
 }
 
 stop_service()
 {
-  systemctl stop displaylink-driver
+  @systemd@/bin/systemctl stop dlm
 }
 
 EOF

displaylink.nix

{ lib, config, pkgs, ... }:
{
nixpkgs.overlays = [
  (self: super: {
    xorg = super.xorg // {
      xorgserver = super.xorg.xorgserver.overrideAttrs (old: {
        name = "xorg-server-1.19.6";
        src = self.fetchurl{
          url = mirror://xorg/individual/xserver/xorg-server-1.19.6.tar.bz2;
          sha256 = "15y13ihgkggmly5s07vzvpn35gzx1w0hrkbnlcvcy05h3lpm0cm7";
        };
      });
    };
    displaylink = super.displaylink.overrideAttrs (old: rec {
      version = "5.1.26";
      name = "displaylink-${version}";
      src = super.requireFile rec {
        name = "displaylink.zip";
        sha256 = "0vkjmqd33kn7vlvbz6alnlb8qvf8mar619cv65v5k05kv75vmh6q";
        message = "MISSING FILE!";
      };

      unpackPhase = lib.replaceStrings [old.version] [version] old.unpackPhase;

      patches = [(self.substituteAll {
        src = ./displaylink-udev-installer.patch;
        inherit (pkgs) systemd;
      })];
    });
    evdi = super.evdi.overrideAttrs (old: rec {
      name = "evdi-${version}";
      version = "1.6.1";

      src = self.fetchFromGitHub {
        owner = "DisplayLink";
        repo = "evdi";
        rev = "v${version}";
        sha256 = "0jy0ia5fsx54d2wv4d2jqnc8rc5x16781a3bcb857apc47zr387h";
      };
    });
  })
  ];
}