[PATCH 8/9] util: provide non-netlink/libnl alternative for virNetDevGetMaster()

[Michal Prívozník]

On 10/1/20 1:14 AM, Laine Stump wrote:
> Lack of this one function (which is called for each active tap device
> every time libvirtd is started) is the one thing preventing a
> "WITHOUT_LIBNL" build of libvirt from being useful. With this
> alternate implementation, guests using standard tap devices will work
> properly.
> 
> Signed-off-by: Laine Stump <laine at redhat.com>
> ---
>   src/util/virnetdev.c | 23 ++++++++++++++++++++++-
>   1 file changed, 22 insertions(+), 1 deletion(-)
> 
> diff --git a/src/util/virnetdev.c b/src/util/virnetdev.c
> index 5221bada7b..c43823c747 100644
> --- a/src/util/virnetdev.c
> +++ b/src/util/virnetdev.c
> @@ -915,9 +915,30 @@ virNetDevGetMaster(const char *ifname, char **master)
>       return 0;
>   }
>   
> +#elif defined(__linux__)
>   
> -#else
> +/* libnl isn't available, so we can't use netlink.
> + * Fall back to using sysfs
> + */
> +int
> +virNetDevGetMaster(const char *ifname, char **master)
> +{
> +    g_autofree char *path = NULL;
> +    g_autofree char *canonical = NULL;
> +
> +    if (virNetDevSysfsFile(&path, ifname, "master") < 0)
> +        return -1;
>   
> +    if (!(canonical = virFileCanonicalizePath(path)))
> +        return -1;
> +
> +    *master = g_path_get_basename(canonical);
> +
> +    VIR_DEBUG("IFLA_MASTER for %s is %s", ifname, *master ? *master : "(none)");
> +    return 0;
> +}
> +
> +#else
>   
>   int
>   virNetDevGetMaster(const char *ifname G_GNUC_UNUSED,
> 

Whoa, building without LIBNL should fail, n'est-ce pas? I'm not saying 
your patch is wrong, it's just that I'm surprised we haven't caught this 
earlier.

Michal