Re: The return value of realloc(p,0)

From	Tim Rentsch <tr.17687@z991.linuxsc.com>
Newsgroups	comp.lang.c
Subject	Re: The return value of realloc(p,0)
Date	2023-09-03 12:01 -0700
Organization	A noiseless patient Spider
Message-ID	<86a5u3qdwt.fsf@linuxsc.com> (permalink)
References	(6 earlier) <ucsejp$3nrkk$5@dont-email.me> <86sf7xspk3.fsf@linuxsc.com> <JCqIM.79177$m8Ke.22576@fx08.iad> <86zg23r6fi.fsf@linuxsc.com> <0g2JM.580001$U3w1.358152@fx09.iad>

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scott@slp53.sl.home (Scott Lurndal) writes:

> Tim Rentsch <tr.17687@z991.linuxsc.com> writes:

[use of address space for zero-byte allocated objects]

>> I think the key word there is sparsely.  A very small
>> fraction of a 64-bit address space suffices, and that
>> needn't be all contiguous either - it's easy to handle
>> a modest number of distinct areas, without too much
>> burden either in space or time.
>
> Perhaps, but vis-a-vis realloc(p,0),  I'd say just don't
> do that rather than adding an arcane 'zero-byte object'
> concept.  Deprecate the feature completely.

Probably a lot of other people agree with you, but the problem
is not just realloc().  A call of malloc(0) has the same problem.
And that problem is not going away - the C standard gives an
implementation-defined choice as to whether malloc(0) returns
NULL or a pointer to "a zero-sized object" (my phrasing).

> In fact, I'd suggest using malloc(), memcpy()/and free() if
> necessary to reallocate something.

I think that idea is nutty.  The realloc() function serves a
useful purpose, including better utilization of memory.  If
someone wants to avoid the weird possibilities of zero-sized
objects, it's easy enough to program around that without
having to completely give up on realloc().

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Re: The return value of realloc(p,0) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-08-30 22:33 -0700
  Re: The return value of realloc(p,0) Vir Campestris <vir.campestris@invalid.invalid> - 2023-08-31 21:03 +0100
    Re: The return value of realloc(p,0) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-01 00:14 -0700
      Re: The return value of realloc(p,0) Vir Campestris <vir.campestris@invalid.invalid> - 2023-09-01 11:32 +0100
        Re: The return value of realloc(p,0) Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-01 17:08 +0000
        Re: The return value of realloc(p,0) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-01 11:42 -0700
          Re: The return value of realloc(p,0) scott@slp53.sl.home (Scott Lurndal) - 2023-09-01 19:06 +0000
            Re: The return value of realloc(p,0) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-03 01:45 -0700
              Re: The return value of realloc(p,0) scott@slp53.sl.home (Scott Lurndal) - 2023-09-03 16:12 +0000
                Re: The return value of realloc(p,0) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-03 12:01 -0700
                Re: The return value of realloc(p,0) scott@slp53.sl.home (Scott Lurndal) - 2023-09-03 21:40 +0000
                Re: The return value of realloc(p,0) Spiros Bousbouras <spibou@gmail.com> - 2023-09-03 23:08 +0000
                Re: The return value of realloc(p,0) Malcolm McLean <malcolm.arthur.mclean@gmail.com> - 2023-09-03 16:23 -0700
                Re: The return value of realloc(p,0) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-03 17:01 -0700
                Re: The return value of realloc(p,0) scott@slp53.sl.home (Scott Lurndal) - 2023-09-04 14:22 +0000
                Re: The return value of realloc(p,0) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-05 05:23 -0700
                Re: The return value of realloc(p,0) Vir Campestris <vir.campestris@invalid.invalid> - 2023-09-04 16:40 +0100
          Re: The return value of realloc(p,0) Vir Campestris <vir.campestris@invalid.invalid> - 2023-09-02 21:40 +0100
      Re: The return value of realloc(p,0) Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-01 17:03 +0000
        Re: The return value of realloc(p,0) Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2023-09-01 17:57 +0000
          Re: The return value of realloc(p,0) Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-01 18:44 +0000
            Re: The return value of realloc(p,0) Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2023-09-01 20:24 +0000
          Re: The return value of realloc(p,0) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-01 11:58 -0700
            Re: The return value of realloc(p,0) Kaz Kylheku <864-117-4973@kylheku.com> - 2023-09-01 19:14 +0000
              Re: The return value of realloc(p,0) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-03 12:03 -0700
        Re: The return value of realloc(p,0) Tim Rentsch <tr.17687@z991.linuxsc.com> - 2023-09-01 11:55 -0700

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