I had the code in these two patches bascially sitting around since 2012,
yes 2012! But I never managed to get the code properly split into patches
and touched up good enough to post it here. This was also hindered by the
fact that I had no ESX test system at hand for the last year or so.
Dawid Zamirski posted some patches [1] to implement virDomainScreenshot
for ESX. So I finally managed to set up some ESX test system again this
weekend and get my old code dusted up. His implementation has two
disadvantages, namely storing the screenshot to a temporary file before
feeding it to a stream and the method of creating the screenshot itself
is availalbe since ESX 4.0 only.
My implementation direcly feeds the screenshot data to a stream and
screenshot creation uses a method available since ESX 2.5.
[1]
https://www.redhat.com/archives/libvir-list/2014-March/msg01786.html