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Re: string types

From: ag
Subject: Re: string types
Date: Sat, 28 Dec 2019 22:44:00 +0200
User-agent: Mutt/1.12.1 (2019-06-15)

Hi Paul,

On Sat, Dec 28, at 10:28 Paul Eggert wrote:
> > Based on the above assumptions this can be extended. First instead of 
> > size_t to
> > return ssize_t, so functions can return -1 and set errno accordingly.
> It's better to use ptrdiff_t for this sort of thing, since it's hardwired into
> the C language (you can't do any better than ptrdiff_t anyway, if you use
> pointer subtraction), whereas ssize_t is merely in POSIX and is narrower than
> ptrdiff_t on some (obsolete?) platforms.

So, let's say we designed this thing without obligating to the past and 
thinking for
the next hundred years (of course with the current knowledge and to lessons 
from the
past), and wanted to make it work with malloc and string type functions, as 
best it
can be done and without worries for overflows and unsigned divisions and all 
kind of confusing things that hunts us altogether after so many years that 
should have been settled by now... is your opininion that this is adequate?

typedef ptrdiff_t msize_t (m for memory here)

> > #define MUL_NO_OVERFLOW ((size_t) 1 << (sizeof (size_t) * 4))
> > #define MEM_IS_INT_OVERFLOW(nmemb, ssize)                             \
> >  (((nmemb) >= MUL_NO_OVERFLOW || (ssize) >= MUL_NO_OVERFLOW) &&       \
> >   (nmemb) > 0 && SIZE_MAX / (nmemb) < (ssize))
> Ouch. That code is not good. An unsigned division at runtime to do memory
> allocation? Gnulib does better than that already. Also, Glibc has some code in
> this area that we could migrate into Gnulib, that could be better yet.

Sorry, i don't have time to do it right now - as i just escaped from a 
snow-storm -
but i will check this for atleast not to spread misleading information (is quite
possible my fault here), so thanks for your comment.

By the way Paul and since i'm self taught by practical experience kind of human
being and joking with zoi here said that at least my teacher is a hall of famer
in the computing history. Isn't this life great!
So true this is also a school for free afterall.

My Honor,

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