Re: [PATCH v2] resolv/nss_dns/dns-host: Get rid of alloca.

[Joe Simmons-Talbott <josimmon@redhat.com>]

On Fri, Aug 11, 2023 at 01:38:43PM -0400, Siddhesh Poyarekar wrote:
> 
> 
> On 2023-08-10 11:57, Joe Simmons-Talbott via Libc-alpha wrote:
> > Since the alloca is a small constant size use an array instead.
> > ---
> > Changes to v1:
> >    * Use sizeof (tmp) rather than NS_MAXDNAME
> >   resolv/nss_dns/dns-host.c | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c
> > index 1d60c51f5e..c8b77bbc35 100644
> > --- a/resolv/nss_dns/dns-host.c
> > +++ b/resolv/nss_dns/dns-host.c
> > @@ -378,6 +378,7 @@ _nss_dns_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat,
> >   			   int *herrnop, int32_t *ttlp)
> >   {
> >     enum nss_status status = check_name (name, herrnop);
> > +  char tmp[NS_MAXDNAME];
> >     if (status != NSS_STATUS_SUCCESS)
> >       return status;
> >     struct resolv_context *ctx = __resolv_context_get ();
> > @@ -395,8 +396,7 @@ _nss_dns_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat,
> >      */
> >     if (strchr (name, '.') == NULL)
> >       {
> > -      char *tmp = alloca (NS_MAXDNAME);
> 
> You could keep tmp here, it doesn't have to go into the higher scope.

I moved it back in v3[1].

[1] https://sourceware.org/pipermail/libc-alpha/2023-August/150901.html

Thanks,
Joe
> 
> > -      const char *cp = __res_context_hostalias (ctx, name, tmp, NS_MAXDNAME);
> > +      const char *cp = __res_context_hostalias (ctx, name, tmp, sizeof (tmp));
> >         if (cp != NULL)
> >   	name = cp;
> >       }
>