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Message-ID: <2402240.lMG0q3WddN@petrie>
Date: Sat, 01 Aug 2020 10:23:35 -0600
From: Ariadne Conill <ariadne@...eferenced.org>
To: musl@...ts.openwall.com
Cc: Markus Wichmann <nullplan@....net>
Subject: Re: [PATCH] implement recallocarray(3)
On Saturday, 1 August 2020 09:52:28 MDT Markus Wichmann wrote:
> On Sat, Aug 01, 2020 at 08:46:58AM -0600, Ariadne Conill wrote:
> > +void *recallocarray(void *ptr, size_t om, size_t m, size_t n)
> > +{
> > + void *newptr;
> > + size_t old_size, new_size;
> > +
> > + if (n && m > -1 / n) {
> > + errno = ENOMEM;
> > + return 0;
> > + }
> > + new_size = m * n;
> > +
> > + if (n && om > -1 / n) {
> > + errno = EINVAL;
> > + return 0;
> > + }
> > + old_size = om * n;
> > +
> > + if (new_size <= old_size) {
> > + memset((char *) ptr + new_size, 0, old_size - new_size);
> > + }
> > +
> > + newptr = reallocarray(ptr, m, n);
> > + if (new_size > old_size) {
> > + memset((char *) ptr + old_size, 0, new_size - old_size);
> > + }
> > +
> > + return newptr;
> > +}
>
> Is there a reason for the call to reallocarray? The multiplication m * n
> has already been tested for overflow and executed at that point. Might
> as well just call realloc() there, right?
Good catch. I decided to use reallocarray() simply for clarity, but I can
change it to a realloc() call.
Ariadne
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