vmix.nix/lib/images/macos/helpers/customizeImage.nix

# Customize a macOS image by booting it with a VMIX volume: the vmix agent
# (LaunchDaemon installed by makeImage) runs `script` as root, records the exit
# status on the volume and powers off. Optionally re-installs OpenCore with a new
# SMBIOS identity (`smbios`). Counterpart of the Windows auditScript flow.
#
# Templates provide:
#   script  — sh script run as root on the booted system
#   files   — [{ source; name; }] extra files placed next to it on /Volumes/VMIX
#   smbios  — { model? serial? mlb? uuid? mac? seed? } → fresh OpenCore config in the ESP
{ pkgs, lib, qemu, ident, makeVmixVolume, makeOpenCore, installBootloader, vmixReadback, vmDriver, ... }:
originalImage: {
  name ? "",
  script ? "",
  files ? [],
  smbios ? null,
  diskSize ? "",
  impure ? true,
  vncDisplay ? null,
  smp ? 4,
  memSize ? 4096,
  cpu ? qemu.defaultCpu,
  timeout ? 3600,
}:
let
  originalImageName = lib.strings.removeSuffix "-vmix" (lib.strings.removeSuffix ".qcow2" originalImage.name);
  customImageName = (if name != "" then name else "custom") + "-${originalImageName}-vmix.qcow2";
  resultImg = "./disk.qcow2";
  hasScript = script != "";
  hasSmbios = smbios != null;

  model = originalImage.model or "MacPro7,1";
  seed = if hasSmbios && (smbios.seed or null) != null then smbios.seed else null;
  mac = if !hasSmbios then originalImage.macAddress
        else if (smbios.mac or null) != null then smbios.mac
        else if seed != null then ident.macFromSeed seed
        else originalImage.macAddress;
  uuid = if !hasSmbios then null
         else if (smbios.uuid or null) != null then smbios.uuid
         else if seed != null then ident.uuidFromSeed seed
         else originalImage.opencore.uuid;
  esp = if hasSmbios
    then makeOpenCore ({
        name = "${name}-${originalImageName}-opencore";
        model = smbios.model or model;
        inherit mac uuid;
      } // builtins.removeAttrs smbios [ "seed" "mac" "uuid" "model" ])
    else originalImage.opencore;

  runScript = pkgs.writeText "${name}-vmix-run.sh" ''
    #!/bin/sh
    echo "=== vmix: ${name} ==="
    ${script}
  '';
  vmixVol = makeVmixVolume {
    name = "${name}-${originalImageName}";
    files = [ { source = runScript; name = "vmix-run.sh"; } ] ++ files;
  };
  driverPython = pkgs.python3.withPackages (p: [ p.pillow ]);

  bootCommands = lib.optionalString hasScript ''
    cp ${vmixVol} vmix.img
    chmod +w vmix.img
    cp ${pkgs.OVMF.fd}/FV/OVMF_VARS.fd vars.fd
    chmod +w vars.fd

    VMIX_DISPLAY="-display none"
    ${lib.optionalString (vncDisplay != null) ''VMIX_DISPLAY="-display none -vnc ${vncDisplay}"''}
    ${lib.optionalString (vncDisplay == null) ''
      VMIX_DF=$(ls -t /tmp/.vmix-display-* 2>/dev/null | head -1)
      if [ -n "$VMIX_DF" ] && [ "$(stat -c %s "$VMIX_DF")" -lt 256 ] && ! grep -q -P '[^\x20-\x7e\n]' "$VMIX_DF"; then
        export DISPLAY=$(tr -d '\n' < "$VMIX_DF")
        export HOME=$(mktemp -d)
        export XDG_RUNTIME_DIR=$HOME
        export SDL_VIDEODRIVER=x11
        VMIX_DISPLAY="-display sdl"
      fi
    ''}

    echo "=== vmix: booting ${originalImageName} for ${name} ==="
    python3 ${vmDriver} --mode boot --name "${name}-${originalImageName}" --timeout ${toString timeout} -- \
      qemu-system-x86_64 $VMIX_DISPLAY \
      ${qemu.machineArgs { inherit cpu smp memSize; }} \
      ${qemu.firmwareArgs "vars.fd"} \
      ${qemu.sataDrive { id = "system"; port = 0; file = resultImg; }} \
      ${qemu.sataDrive { id = "vmix"; port = 1; file = "vmix.img"; format = "raw"; }} \
      ${qemu.netArgs { mac = originalImage.macAddress; }} \
      || { echo "vmix: VM failed during ${name} (see /tmp/vmix-macos/${name}-${originalImageName})"; exit 1; }

    ${vmixReadback "vmix.img"}
    [ "$STATUS" = "0" ] || { echo "vmix: ${name} script failed (status '$STATUS')"; exit 1; }
    echo "=== vmix: ${name} complete ==="
  '';

  builtImage = pkgs.runCommand customImageName ({
    nativeBuildInputs = with pkgs; [ pkgs.qemu mtools driverPython libguestfs-with-appliance ];
    requiredSystemFeatures = [ "kvm" ];
  } // lib.optionalAttrs impure { __noChroot = true; }) ''
    qemu-img create -q -f qcow2 -b ${originalImage} -F qcow2 ${resultImg}
    [ -n "${diskSize}" ] && qemu-img resize ${resultImg} ${diskSize}
    ${bootCommands}
    ${lib.optionalString hasSmbios (installBootloader { inherit esp; image = resultImg; })}
    mv ${resultImg} $out
  '';
in
  builtImage // { _vmixOsType = "macos"; macAddress = mac; opencore = esp; model = esp.model or model; }