Block sizes from OSM data

My city has big blocks. One close to mine is around 6km of circumference. I wanted to make a map that show the sizes of the blocks. What I have is a rendering DB for my area. Let's see what I can do. An obvious solution would be to use any routing database, which would convert squiggly segments into edges of a graph. I feebly tried that, but no routing system I know is packaged for Debian, and one of them asked me to compile it. I could compile it, but I was lazy that way. So the plan is this: take the whole street network1 and recursively remove the dead end streets. The recursion part is because there are areas where there are whole branches of dead end streets, so if in one pass a street A might look not dead because it connects to another B, but B is removed, the next pass should remove A too. So, for each street, take each end, and see how many other segments it's connected to; if 0, it's a dead end and we should remove it. Keep going until no new streets were removed. One problem