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Message-ID: <20250605214253.GD1827@brightrain.aerifal.cx>
Date: Thu, 5 Jun 2025 17:42:53 -0400
From: Rich Felker <dalias@...c.org>
To: enh <enh@...gle.com>
Cc: musl@...ts.openwall.com
Subject: Re: c23 memset_explicit()
On Wed, Jun 04, 2025 at 01:35:53PM -0400, enh wrote:
> did memset_explicit() make it in, or was this blocked on rewriting
> explicit_bzero() to call memset_explicit()?
>
> (we're starting to see more users and thus more portability problems.)
I don't think it's blocked. I just haven't gone thru and started
merging C23 stuff yet. Whether to rewrite explicit_bzero in terms of
it is a separate question.
Rich
> On Tue, Mar 19, 2024 at 8:59 AM Aaron Peter Bachmann <aaron_ng@...de.at> wrote:
> >
> > I recognized neither
> > https://git.musl-libc.org/cgit/musl
> > nor
> > https://forge.icube.unistra.fr/icps/musl/-/branches
> > seem to include c23 memset_explicit().
> > Or it slipped my attention.
> >
> > So I provide a patch. It compiles but is otherwise untested.
> > It is trivial enough that you would spot an error when merging.
> > No guards for c23 as mem is a reserved prefix.
> > It closely follows explicit_bzero.c. So I assume it fits into the coding
> > style musl uses.
> >
> > Regards, Aaron Peter Bachmann
> >
> >
> > diff --git a/include/string.h b/include/string.h
> > index 83e2b946..563b3b0a 100644
> > --- a/include/string.h
> > +++ b/include/string.h
> > @@ -27,6 +27,7 @@ extern "C" {
> > void *memcpy (void *__restrict, const void *__restrict, size_t);
> > void *memmove (void *, const void *, size_t);
> > void *memset (void *, int, size_t);
> > +void *memset_explicit(void *, int, size_t);
> > int memcmp (const void *, const void *, size_t);
> > void *memchr (const void *, int, size_t);
> >
> > diff --git a/src/string/memset_explicit.c b/src/string/memset_explicit.c
> > new file mode 100644
> > index 00000000..ac54f0cf
> > --- /dev/null
> > +++ b/src/string/memset_explicit.c
> > @@ -0,0 +1,8 @@
> > +#include <string.h>
> > +
> > +void *memset_explicit(void *d, int c, size_t n)
> > +{
> > + d = memset(d, c, n);
> > + __asm__ __volatile__ ("" : : "r"(d) : "memory");
> > + return d;
> > +}
> >
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