[1/2] nss: add assert to DB_LOOKUP_FCT (BZ #28752)

  It's interesting if we have a null action list,
so an assert is worthwhile.

Suggested-by: DJ Delorie <dj@redhat.com>
Signed-off-by: Sam James <sam@gentoo.org>
---
 nss/XXX-lookup.c | 5 +++++
 1 file changed, 5 insertions(+)
  

On 25/05/2022 21:20, Sam James via Libc-alpha wrote:
> It's interesting if we have a null action list,
> so an assert is worthwhile.
> 
> Suggested-by: DJ Delorie <dj@redhat.com>
> Signed-off-by: Sam James <sam@gentoo.org>
> ---
>  nss/XXX-lookup.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/nss/XXX-lookup.c b/nss/XXX-lookup.c
> index db95937674..793dde976e 100644
> --- a/nss/XXX-lookup.c
> +++ b/nss/XXX-lookup.c
> @@ -15,6 +15,7 @@
>     License along with the GNU C Library; if not, see
>     <https://www.gnu.org/licenses/>.  */
>  
> +#include <assert.h>
>  #include "nsswitch.h"
>  
>  /*******************************************************************\
> @@ -54,6 +55,10 @@ DB_LOOKUP_FCT (nss_action_list *ni, const char *fct_name, const char *fct2_name,
>  
>    *ni = DATABASE_NAME_SYMBOL;
>  
> +  // We want to know about it if we've somehow got a NULL action list;
> +  // in the past, we had bad state if seccomp interfered with setup.

I think the expected comment format is the usual C90 one (/* ... */).

> +  assert(*ni != NULL);
> +
>    return __nss_lookup (ni, fct_name, fct2_name, fctp);
>  }
>  libc_hidden_def (DB_LOOKUP_FCT)

Are you trying to assure that DATABASE_NAME_SYMBOL is not NULL here? If
so I think it would be simpler to just use a _Static_assert.
  

> On 27 May 2022, at 18:07, Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org> wrote:
> 
> 
> 
> On 25/05/2022 21:20, Sam James via Libc-alpha wrote:
>> It's interesting if we have a null action list,
>> so an assert is worthwhile.
>> 
>> Suggested-by: DJ Delorie <dj@redhat.com>
>> Signed-off-by: Sam James <sam@gentoo.org>
>> ---
>> nss/XXX-lookup.c | 5 +++++
>> 1 file changed, 5 insertions(+)
>> 
>> diff --git a/nss/XXX-lookup.c b/nss/XXX-lookup.c
>> index db95937674..793dde976e 100644
>> --- a/nss/XXX-lookup.c
>> +++ b/nss/XXX-lookup.c
>> @@ -15,6 +15,7 @@
>> License along with the GNU C Library; if not, see
>> <https://www.gnu.org/licenses/>. */
>> 
>> +#include <assert.h>
>> #include "nsswitch.h"
>> 
>> /*******************************************************************\
>> @@ -54,6 +55,10 @@ DB_LOOKUP_FCT (nss_action_list *ni, const char *fct_name, const char *fct2_name,
>> 
>> *ni = DATABASE_NAME_SYMBOL;
>> 
>> + // We want to know about it if we've somehow got a NULL action list;
>> + // in the past, we had bad state if seccomp interfered with setup.
> 
> I think the expected comment format is the usual C90 one (/* ... */).

Right.

> 
>> + assert(*ni != NULL);
>> +
>> return __nss_lookup (ni, fct_name, fct2_name, fctp);
>> }
>> libc_hidden_def (DB_LOOKUP_FCT)
> 
> Are you trying to assure that DATABASE_NAME_SYMBOL is not NULL here? If
> so I think it would be simpler to just use a _Static_assert.

I'm sorry, I'm not sure what the expression ought to be in that case. I get that
some of it is figured out at build-time given we're using some macros, but
I don't see what to test against to check it's not NULL statically?

Best,
sam