function to list domains under vpopmail control

[Sean P. Scanlon]

is there an un-documented function that
will return a list of domains that are under vpopmail control? 

i looked thru vpopmail.h but saw nothing like this 

if there is none, could it be done? I suppose reading thru
qmail/control/virtualdomains might be a good place to start. 

I would be willing to write something like, but am not sure there is
a reliable central source of this information. 

Thanks,
 -sean