[libvirt] [PATCH] nss: use more strict check for automatic enabling

[Michal Privoznik]

On 21.03.2016 06:21, Roman Bogorodskiy wrote:
> Currently nss plugin is automatically enabled if nss.h header exists and
> --without-nss-plugin is not specified. However, presence of the nss.h
> header does not guarantee a compatible interface, so check for struct
> gaih_addrtuple to make sure it's enabled only on platforms where it
> could be built.
> ---
>  m4/virt-nss.m4 | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/m4/virt-nss.m4 b/m4/virt-nss.m4
> index 3fa4ad3..bc054db 100644
> --- a/m4/virt-nss.m4
> +++ b/m4/virt-nss.m4
> @@ -25,12 +25,14 @@ AC_DEFUN([LIBVIRT_CHECK_NSS],[
>  
>    fail=0
>    if test "x$with_nss_plugin" != "xno" ; then
> -    AC_CHECK_HEADERS([nss.h], [
> +    AC_CHECK_TYPE([struct gaih_addrtuple], [
>          with_nss_plugin=yes
>        ],[
>          if test "x$with_nss_plugin" = "xyes" ; then
>            fail = 1
>          fi
> +      ],[
> +        #include <nss.h>
>        ])
>  
>      if test $fail = 1 ; then
> 

While this would fix the build, it would disable the whole feature on
freebsd. The problem is with the structure that is needed just for
_nss_libvirt_gethostbyname4_r(). Should we change the code in that way
that the function is built conditionally when the structure is present?
That way we still could have _gethostbyname3_r() on systems providing
the header file but not having the structure.

Michal