[PATCH v3] Implement C23 memset_explicit (bug 32378)

[Collin Funk]

Joseph Myers <josmyers@redhat.com> writes:

> Add the C23 memset_explicit function to glibc.  Everything here is
> closely based on the approach taken for explicit_bzero.  This includes
> the bits that relate to internal uses of explicit_bzero within glibc
> (although we don't currently have any such internal uses of
> memset_explicit), and also includes the nonnull attribute (when we
> move to nonnull_if_nonzero for various functions following C2y, this
> function should be included in that change).
>
> The function is declared both for __USE_MISC and for __GLIBC_USE (ISOC23)
> (so by default not just for compilers defaulting to C23 mode).
>
> Tested for x86_64 and x86.
>
> ---
>
> Changed in v2: declare for __USE_MISC.
>
> Changed in v3: also apply the __USE_MISC change to
> bits/string_fortified.h and remove no-longer-needed _GNU_SOURCE
> conditionals in tst-fortify.c.

Looks good, thanks.

Reviewed-by: Collin Funk <collin.funk1@gmail.com>

Collin