Obtaining offset given location string (via library call?)

Hello. I'm looking for a "C" function I can call (ideally from Python, but I can write a wrapper) which returns for me the current offset from UTC given one of the location strings, such as "Australia/Sydney". Any ideas? I was very hopeful with "zdump" however what I need is the offset (yes, I could probably hack the offset from the output of zdump) and further, I'd rather not have to start a new process to obtain this information, thus having it in library form would be perfect. Thank you so much! Clark