All of the above, I guess. It wants to reuse code in fscanf(), but for that it needs a FILE * interface. But to create that, it needs to implement EOF-handling

All of the above, I guess. It wants to reuse code in fscanf(), but for that it needs a FILE * interface. But to create that, it needs to implement EOF-handling, and to do that it needs to provide a size, so it has to call strlen(). I had no idea. :|