/* this can be increased when necessary - don't expose to userland */
#define NETLINK_MAX_COOKIE_LEN 20
+#define NETLINK_MAX_FMTMSG_LEN 80
/**
* struct netlink_ext_ack - netlink extended ACK report struct
* @miss_nest: nest missing an attribute (%NULL if missing top level attr)
* @cookie: cookie data to return to userspace (for success)
* @cookie_len: actual cookie data length
+ * @_msg_buf: output buffer for formatted message strings - don't access
+ * directly, use %NL_SET_ERR_MSG_FMT
*/
struct netlink_ext_ack {
const char *_msg;
u16 miss_type;
u8 cookie[NETLINK_MAX_COOKIE_LEN];
u8 cookie_len;
+ char _msg_buf[NETLINK_MAX_FMTMSG_LEN];
};
/* Always use this macro, this allows later putting the
* message into a separate section or such for things
* like translation or listing all possible messages.
- * Currently string formatting is not supported (due
- * to the lack of an output buffer.)
+ * If string formatting is needed use NL_SET_ERR_MSG_FMT.
*/
#define NL_SET_ERR_MSG(extack, msg) do { \
static const char __msg[] = msg; \
__extack->_msg = __msg; \
} while (0)
+/* We splice fmt with %s at each end even in the snprintf so that both calls
+ * can use the same string constant, avoiding its duplication in .ro
+ */
+#define NL_SET_ERR_MSG_FMT(extack, fmt, args...) do { \
+ struct netlink_ext_ack *__extack = (extack); \
+ \
+ if (!__extack) \
+ break; \
+ if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \
+ "%s" fmt "%s", "", ##args, "") >= \
+ NETLINK_MAX_FMTMSG_LEN) \
+ net_warn_ratelimited("%s" fmt "%s", "truncated extack: ", \
+ ##args, "\n"); \
+ \
+ do_trace_netlink_extack(__extack->_msg_buf); \
+ \
+ __extack->_msg = __extack->_msg_buf; \
+} while (0)
+
#define NL_SET_ERR_MSG_MOD(extack, msg) \
NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)
+#define NL_SET_ERR_MSG_FMT_MOD(extack, fmt, args...) \
+ NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args)
+
#define NL_SET_BAD_ATTR_POLICY(extack, attr, pol) do { \
if ((extack)) { \
(extack)->bad_attr = (attr); \