archive method

Uint8List? archive(
  1. String sha256
)

The cached archive whose SHA-256 is sha256, checked again; null when missing, damaged (a damaged copy is deleted), or busy in another process.

Throws ArgumentError unless sha256 is 64 lowercase hex digits.

Implementation

Uint8List? archive(String sha256) {
  final file = _archiveFile(sha256);
  try {
    if (!file.existsSync()) return null;
    final bytes = file.readAsBytesSync();
    if (Sha256.hexOf(bytes) == sha256) return bytes;
    file.deleteSync();
  } on FileSystemException {
    // Another process is replacing it, or it can't be read: a miss.
  }
  return null;
}