void FdInStream::readBytes(void* data, int length)
{
  if (length < MIN_BULK_SIZE) {
    InStream::readBytes(data, length);
    return;
  }

  U8* dataPtr = (U8*)data;

  int n = end - ptr;
  if (n > length) n = length;

  memcpy(dataPtr, ptr, n);
  dataPtr += n;
  length -= n;
  ptr += n;

  while (length > 0) {
    n = readWithTimeoutOrCallback(dataPtr, length);
    dataPtr += n;
    length -= n;
    offset += n;
  }
}
The software writes data past the end, or before the beginning, of the intended buffer.