| Message ID | 20230705185835.1474212-1-josimmon@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | resolv/nss_dns/dns-host: Note the usage of alloca is safe. | expand |
On Wed, Jul 05, 2023 at 02:58:35PM -0400, Joe Simmons-Talbott wrote: > Since the size is relatively small and constant add a comment that the > usage of alloca is safe. Ping. Thanks, Joe > --- > resolv/nss_dns/dns-host.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c > index 1d60c51f5e..d3aaeec293 100644 > --- a/resolv/nss_dns/dns-host.c > +++ b/resolv/nss_dns/dns-host.c > @@ -395,6 +395,7 @@ _nss_dns_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat, > */ > if (strchr (name, '.') == NULL) > { > + /* alloca is safe here since the size is small and constant. */ > char *tmp = alloca (NS_MAXDNAME); > const char *cp = __res_context_hostalias (ctx, name, tmp, NS_MAXDNAME); > if (cp != NULL) > -- > 2.39.2 >
On Jul 05 2023, Joe Simmons-Talbott via Libc-alpha wrote: > Since the size is relatively small and constant add a comment that the > usage of alloca is safe. > --- > resolv/nss_dns/dns-host.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c > index 1d60c51f5e..d3aaeec293 100644 > --- a/resolv/nss_dns/dns-host.c > +++ b/resolv/nss_dns/dns-host.c > @@ -395,6 +395,7 @@ _nss_dns_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat, > */ > if (strchr (name, '.') == NULL) > { > + /* alloca is safe here since the size is small and constant. */ > char *tmp = alloca (NS_MAXDNAME); Since this is a constant allocation, I think it would be better to just declare it as a regular array in the enclosing block.
On Wed, 2023-07-05 at 14:58 -0400, Joe Simmons-Talbott via Libc-alpha wrote: > Since the size is relatively small and constant add a comment that the > usage of alloca is safe. > --- > resolv/nss_dns/dns-host.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c > index 1d60c51f5e..d3aaeec293 100644 > --- a/resolv/nss_dns/dns-host.c > +++ b/resolv/nss_dns/dns-host.c > @@ -395,6 +395,7 @@ _nss_dns_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat, > */ > if (strchr (name, '.') == NULL) > { > + /* alloca is safe here since the size is small and constant. */ > char *tmp = alloca (NS_MAXDNAME); But then why don't we simply say "char tmp[NS_MAXDNAME];" here? > const char *cp = __res_context_hostalias (ctx, name, tmp, NS_MAXDNAME); > if (cp != NULL)
On Thu, Aug 10, 2023 at 10:07:34PM +0800, Xi Ruoyao wrote: > On Wed, 2023-07-05 at 14:58 -0400, Joe Simmons-Talbott via Libc-alpha wrote: > > Since the size is relatively small and constant add a comment that the > > usage of alloca is safe. > > --- > > resolv/nss_dns/dns-host.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c > > index 1d60c51f5e..d3aaeec293 100644 > > --- a/resolv/nss_dns/dns-host.c > > +++ b/resolv/nss_dns/dns-host.c > > @@ -395,6 +395,7 @@ _nss_dns_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat, > > */ > > if (strchr (name, '.') == NULL) > > { > > + /* alloca is safe here since the size is small and constant. */ > > char *tmp = alloca (NS_MAXDNAME); > > But then why don't we simply say "char tmp[NS_MAXDNAME];" here? > Dropped in favor of https://sourceware.org/pipermail/libc-alpha/2023-August/150819.html Thanks, Joe > > const char *cp = __res_context_hostalias (ctx, name, tmp, NS_MAXDNAME); > > if (cp != NULL) > > -- > Xi Ruoyao <xry111@xry111.site> > School of Aerospace Science and Technology, Xidian University >
diff --git a/resolv/nss_dns/dns-host.c b/resolv/nss_dns/dns-host.c index 1d60c51f5e..d3aaeec293 100644 --- a/resolv/nss_dns/dns-host.c +++ b/resolv/nss_dns/dns-host.c @@ -395,6 +395,7 @@ _nss_dns_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat, */ if (strchr (name, '.') == NULL) { + /* alloca is safe here since the size is small and constant. */ char *tmp = alloca (NS_MAXDNAME); const char *cp = __res_context_hostalias (ctx, name, tmp, NS_MAXDNAME); if (cp != NULL)