Re: MOST_POSITIVE_FIXNUM and maximum buffer/string size

[Stefan Monnier <monnier@iro.umontreal.ca>]

> Unless I'm missing something, this means we need to limit buffer sizes
> to MOST_POSITIVE_FIXNUM-1.

That's right (I wish I could change BEGV to 0, but that would break
a bit too much Elisp code, sadly, tho most of Emacs' own Elisp code is
somewhat clean in this respect).

> A related issue is with strings.  String positions are zero-based, so
> there's no problem with overflow there.  But if a string whose length
> is MOST_POSITIVE_FIXNUM is inserted into a buffer, we will again have
> an overflow.  So should we limit strings to MOST_POSITIVE_FIXNUM-1 as
> well?

I don't think so: when inserting a string, we have to check that we
don't make the buffer too large anyway, so there's no need to do
anything special in this respect.  Of course, we can also limit strings
to MOST_POSITIVE_FIXNUM-1, and I don't think anybody will mind, but it's
not necessary AFAIK.


        Stefan