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

[Siddhesh Poyarekar <siddhesh@gotplt.org>]

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.

> -      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;
>       }