core/pkgs/by-name/fo/fontconfig/make-fonts-conf.nix

{ runCommand, stdenv, lib, libxslt, fontconfig, dejavu_fonts }:

let fontconfig_ = fontconfig;
in { fontconfig ? fontconfig_
  # an array of fonts, e.g. `[ pkgs.dejavu_fonts.minimal ]`
, fontDirectories, impureFontDirectories ? [
  # nix user profile
  "~/.nix-profile/lib/X11/fonts"
  "~/.nix-profile/share/fonts"
] ++ lib.optional stdenv.isDarwin "~/Library/Fonts" ++ [
  # FHS paths for non-NixOS platforms
  "/usr/share/fonts"
  "/usr/local/share/fonts"
]
# darwin paths
  ++ lib.optionals stdenv.isDarwin [
    "/Library/Fonts"
    "/System/Library/Fonts"
  ]
  # nix default profile
  ++ [
    "/nix/var/nix/profiles/default/lib/X11/fonts"
    "/nix/var/nix/profiles/default/share/fonts"
  ] }:

runCommand "fonts.conf" {
  nativeBuildInputs = [ libxslt ];
  buildInputs = [ fontconfig ];
  inherit fontDirectories;
  # Add a default font for non-nixos systems, <1MB and in nixos defaults.
  impureFontDirectories = impureFontDirectories ++ [ dejavu_fonts.minimal ];
} ''
  xsltproc --stringparam fontDirectories "$fontDirectories" \
    --stringparam impureFontDirectories "$impureFontDirectories" \
    --path ${fontconfig.out}/share/xml/fontconfig \
    ${./make-fonts-conf.xsl} ${fontconfig.out}/etc/fonts/fonts.conf \
    > $out
''