[libvirt] [PATCHv3 1/2] conf: add <listen> subelement to domain <graphics> element

[Laine Stump]

Sigh.

I'd meant to add more explanation in the [0/2] mail, but forgot to add 
"--compose" on my git send-mail commandline.

Just a couple of points:

1) The old fields in the unions of virDomainGraphicsDef that used to 
store the attributes from <graphics> (listen, port, tlsPort, autoport) 
have all been removed. To maintain backward compatibility, if attributes 
are put into <graphics> (rather than making a separate <listen> 
subelement), they will be stored in the first virDomainGraphicsListenDef 
(aka <listen> element) which will be created automatically by the new 
helper functions if needed.

2) About the helper functions - in the old code, all accesses to the 
"listen" information was done by referencing the data in 
virDomainGraphicsDef directly. To continue doing that now that the data 
structure is more complex would mean that the existing code that uses 
those attributes would become huge, ugly, and difficult to understand. 
To avoid this, I made a set of helper functions for getting and setting 
all the attributes of virDomainGraphicsListenDef. Aw with the data 
structures themselves, the helper functions are designed to support an 
array of <listen>s. However, none of our hypervisor drivers know what to 
do with more than one <listen> right now, so when converting existing 
code you will see that the index arg is always 0.

3) Patch 1/2 looks large, but much of it is mechanical changes, and it 
all must be in one patch to maintain bisectability. It can be thought of 
in three pieces:

1) The parser/formatter additions (including RNG and documentation)

2) updates to hypervisor drivers to access the listen/port data using 
the new helper functions

3) adding the extra <listen> subelement to every <graphics> element in 
every test domain XML file (as well as adding a couple of new cases 
specific to this feature).