[libvirt] compressed stream support

I want to able to get VolumeUpload and VolumeUpload compressed on the fly (for example to minimize network load) Some times ago i ask this question in this list, and get some suggestions from developers. But as i see, May be not good to detect compressor from libvirt config, but create new stream functions that have in flags somewhere compressor type. So when data uploaded/downloaded stream Recv/Send functions able to compress/decompress on the fly. But i'm not understand some things: 1) user run volumedownload with offset (uncompressed size) and length. But when user recieve data - resulted len < requested len. How to deal with this? 2) how to display progress when downloading/uploading data? in case of uncompressed size thing very simple (i know all size and transfered), but in case of compressed data how to determine progress ? Thanks! -- Vasiliy Tolstov, e-mail: v.tolstov(a)selfip.ru