[pacman-dev] How does pacman fetch the PKGINFO files for all packages during a --refresh operation

How does pacman fetch the PKGINFO files for all packages during a --refresh operation? Is there a way to extract a single file from an archive even over the network or are there all store in one single location? I'm asking because I'm reimplementing pacman from scratch in C# and I was uncertain how I can achieve the refresh the refresh optimally and I'm a little short on time, so if you can spare me browsing through the source tree I'd be most helpful. Best Regards, Bozhidar