[File] Help implementing "octal" indirect offset support

[Michał Górny]

On Fri, 2022-09-09 at 11:11 -0400, Christos Zoulas wrote:
> Yes, that's right ID3 is the closest thing we have for now. But you don't need
> to do deal with them as quad types since the union also contains a string.
> You can parse the value from the string directly I think.
> 

Thanks, I didn't realize I can implement indirect offsets on top of
strings.  I've managed to do that.  However, now I've hit another
obstacle: I need to round the result up to the 512-byte boundary,
and I can't think of a good way of doing that.  I suppose I'm just
trying to do things that are too complex for file(1).

-- 
Best regards,
Michał Górny