> I think this will just give you the LENGTH of the file? So, I don't
> know if it matters, but ISTR that Gimp uses files with holes, and
> therefore LENGTH != SIZE.
Oh, I didn't know this.
In any case, the program *does* know (or should) know the number of
tiles that it can have (tile cache size), the number of tiles in
memory (referenced tiles plus unswapped tiles), and number of tiles on
disk (swapped tiles). So you really don't care much about the size of
the swapfile, since it can only get so big.