template<class DEST, class SRC>
int64 CopyGeneric(DEST& dest, SRC& src, int64 count = INT64_MAX, Gate<int64, int64> progress = Null, int chunk_size = 1024 * 64)
{
	int block = (int)min<int64>(count, chunk_size);
	Buffer<byte> temp(block);
	int loaded;
	int64 done = 0;
	int64 total = count;
	while(count > 0 && (loaded = src.Get(~temp, (int)min<int64>(count, block))) > 0) {
		dest.Put(~temp, loaded);
		if(dest.IsError() || src.IsError())
			return -1;
		count -= loaded;
		done += loaded;
		if(progress(done, total))
			return -1;
	}
	return done;
}