How to use

readFully

method

in

com.google.common.io.LittleEndianDataInputStream

  private static byte [] getByteArray(LittleEndianDataInputStream ledis) throws IOException {
    short fieldLength = ledis.readShort();
    byte [] value = new byte[fieldLength];
    ledis.readFully(value);
    return value;
  }
}

private static void checkStartBytes(KdbxHeader kdbxHeader, InputStream decryptedInputStream) throws IOException {
  LittleEndianDataInputStream ledis = new LittleEndianDataInputStream(decryptedInputStream);
  byte [] startBytes = new byte[32];
  ledis.readFully(startBytes);
  if (!Arrays.equals(startBytes, kdbxHeader.getStreamStartBytes())) {
    throw new IllegalStateException("Inconsistent stream start bytes. This usually means the credentials were wrong.");
  }
}

private byte[] readNextBlock() throws IOException {
  int read = stream.read();
  if (read < 0) return null;
  byte[] checksum = new byte[16];
  checksum[0] = (byte)read;
  // checksum - 16 bytes.
  dataWrapper.readFully(checksum, 1, 15);
  ClickHouseBlockChecksum expected = ClickHouseBlockChecksum.fromBytes(checksum);
  // header:
  // 1 byte - 0x82 (shows this is LZ4)
  int magic = dataWrapper.readUnsignedByte();
  if (magic != MAGIC) throw new IOException("Magic is not correct: " + magic);
  // 4 bytes - size of the compressed data including 9 bytes of the header
  int compressedSizeWithHeader = dataWrapper.readInt();
  // 4 bytes - size of uncompressed data
  int uncompressedSize = dataWrapper.readInt();
  int compressedSize = compressedSizeWithHeader - 9; //header
  byte[] block = new byte[compressedSize];
  // compressed data: compressed_size - 9 байт.
  dataWrapper.readFully(block);
  ClickHouseBlockChecksum real = ClickHouseBlockChecksum.calculateForBlock((byte)magic, compressedSizeWithHeader, uncompressedSize, block, compressedSize);
  if (!real.equals(expected)) {
    throw new IllegalArgumentException("Checksum doesn't match: corrupted data.");
  }
  byte[] decompressed = new byte[uncompressedSize];
  LZ4FastDecompressor decompressor = factory.fastDecompressor();
  decompressor.decompress(block, 0, decompressed, 0, uncompressedSize);
  return decompressed;
}

private byte[] readNextBlock() throws IOException {
  int read = stream.read();
  if (read < 0) return null;
  byte[] checksum = new byte[16];
  checksum[0] = (byte)read;
  // checksum - 16 bytes.
  dataWrapper.readFully(checksum, 1, 15);
  ClickHouseBlockChecksum expected = ClickHouseBlockChecksum.fromBytes(checksum);
  // header:
  // 1 byte - 0x82 (shows this is LZ4)
  int magic = dataWrapper.readUnsignedByte();
  if (magic != MAGIC) throw new IOException("Magic is not correct: " + magic);
  // 4 bytes - size of the compressed data including 9 bytes of the header
  int compressedSizeWithHeader = dataWrapper.readInt();
  // 4 bytes - size of uncompressed data
  int uncompressedSize = dataWrapper.readInt();
  int compressedSize = compressedSizeWithHeader - 9; //header
  byte[] block = new byte[compressedSize];
  // compressed data: compressed_size - 9 байт.
  dataWrapper.readFully(block);
  ClickHouseBlockChecksum real = ClickHouseBlockChecksum.calculateForBlock((byte)magic, compressedSizeWithHeader, uncompressedSize, block, compressedSize);
  if (!real.equals(expected)) {
    throw new IllegalArgumentException("Checksum doesn't match: corrupted data.");
  }
  byte[] decompressed = new byte[uncompressedSize];
  LZ4FastDecompressor decompressor = factory.fastDecompressor();
  decompressor.decompress(block, 0, decompressed, 0, uncompressedSize);
  return decompressed;
}