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, \
+ .nlmsg_flags = NLM_F_REQUEST, \
+ }}
+
#endif /* __LIBNETLINK_H__ */
--
2.5.0
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
