Phil Sutter <[email protected]> writes: > This macro aims to simplify most netlink users' pattern to prepare a > request, which is to create an unnamed struct and initialize it: > > | struct { > | struct nlmsghdr n; > | struct whatever foo; > | char buf[arbitrary number]; > | } req; > | > | memset(&req, 0, sizeof(req)); > | req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct whatever)); > | req.n.nlmsg_flags = NLM_F_REQUEST; > > Having this patch applied, the above can be replaced by a static > initializer like so: > > | DECLARE_NLREQ(req, n, struct whatever foo, arbitrary number); > > There is an added benefit, as well: Due to explicit alignment, the > requested tailroom is really as big as requested no matter what size > struct whatever really is. > > Signed-off-by: Phil Sutter <[email protected]> > --- > This patch is RFC because I want to wait for peer review and upstream > acceptance before sending in the big refactoring patch itself. > --- > include/libnetlink.h | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/include/libnetlink.h b/include/libnetlink.h > index 2280c39c670a4..7e12a7b12b55d 100644 > --- a/include/libnetlink.h > +++ b/include/libnetlink.h > @@ -196,5 +196,16 @@ int rtnl_from_file(FILE *, rtnl_listen_filter_t handler, > * messages from dump file */ > #define NLMSG_TSTAMP 15 > > +/* declare a netlink request with initial payload */ > +#define DECLARE_NLREQ(name, hdrname, payload, tailroom) > \ > + struct { \ > + struct nlmsghdr hdrname; \ > + payload; \ > + char __b[tailroom] __attribute__((aligned(NLMSG_ALIGNTO))); \ > + } name = { .hdrname = { \ > + .nlmsg_len = (unsigned long)&name.__b - (unsigned long)&name, \
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