IFLA_PPP_DEV_FD
[IFLA_PPP_DEV_FD] = { .type = NLA_S32 },
if (!data[IFLA_PPP_DEV_FD])
if (nla_get_s32(data[IFLA_PPP_DEV_FD]) < 0)
file = fget(nla_get_s32(data[IFLA_PPP_DEV_FD]));