readHeader static method

Implementation

static Future<(String, int)> readHeader(
  RandomAccessFile raf, {
  String? requiredMagic,
  int? requiredVersion,
}) async {
  final magicBytes = await raf.read(4);
  if (magicBytes.length != 4) {
    throw Exception(
      'Required Magic String Count: `4` And Got `${magicBytes.length}`',
    );
  }
  final magicStr = utf8.decode(magicBytes);
  if (requiredMagic != null && magicStr != requiredMagic) {
    throw Exception(
      'Magic Not Match!.Required: `$requiredMagic` And Got `$magicStr`',
    );
  }
  final versionInt = await raf.readByte();
  if (requiredVersion != null && versionInt != requiredVersion) {
    throw Exception(
      'Version Not Match!.Required: `$requiredVersion` And Got `$versionInt`',
    );
  }
  return (magicStr, versionInt);
}