sit: refactor IS_SIT_LINK_ASSERT()

Also check for NULL link and dereference link before
basic error checking.

Also move the declaration of the @sit member inside
the macro. Obviously, the macro must now always come at
first, after declaring local auto variables.

Signed-off-by: Thomas Haller <thaller@redhat.com>

1 files changed, 26 insertions, 53 deletions

diff --git a/lib/route/link/sit.c b/lib/route/link/sit.c
index fc0fd75..3306f53 100644
--- a/lib/route/link/sit.c
+++ b/lib/route/link/sit.c
@@ -362,11 +362,16 @@ static struct rtnl_link_info_ops sit_info_ops = {
 	.io_free                = sit_free,
 };
 
-#define IS_SIT_LINK_ASSERT(link)                                           \
-        if ((link)->l_info_ops != &sit_info_ops) {                         \
-                APPBUG("Link is not a sit link. set type \"sit\" first."); \
-                return -NLE_OPNOTSUPP;                                     \
-        }
+#define IS_SIT_LINK_ASSERT(link, sit)                                              \
+        struct sit_info *sit;                                                      \
+        do {                                                                       \
+                const struct rtnl_link *_link = (link);                            \
+                if (!_link || _link->l_info_ops != &sit_info_ops) {                \
+                        APPBUG("Link is not a sit link. set type \"sit\" first."); \
+                        return -NLE_OPNOTSUPP;                                     \
+                }                                                                  \
+                (sit) = _link->l_info;                                             \
+        } while (0)
 
 struct rtnl_link *rtnl_link_sit_alloc(void)
 {
@@ -432,9 +437,7 @@ int rtnl_link_sit_add(struct nl_sock *sk, const char *name)
  */
 int rtnl_link_sit_set_link(struct rtnl_link *link,  uint32_t index)
 {
-	struct sit_info *sit = link->l_info;
-
-	IS_SIT_LINK_ASSERT(link);
+	IS_SIT_LINK_ASSERT(link, sit);
 
 	sit->link = index;
 	sit->sit_mask |= SIT_ATTR_LINK;
@@ -450,9 +453,7 @@ int rtnl_link_sit_set_link(struct rtnl_link *link,  uint32_t index)
  */
 uint32_t rtnl_link_sit_get_link(struct rtnl_link *link)
 {
-	struct sit_info *sit = link->l_info;
-
-	IS_SIT_LINK_ASSERT(link);
+	IS_SIT_LINK_ASSERT(link, sit);
 
 	return sit->link;
 }
@@ -466,9 +467,7 @@ uint32_t rtnl_link_sit_get_link(struct rtnl_link *link)
  */
 int rtnl_link_sit_set_local(struct rtnl_link *link, uint32_t addr)
 {
-	struct sit_info *sit = link->l_info;
-
-	IS_SIT_LINK_ASSERT(link);
+	IS_SIT_LINK_ASSERT(link, sit);
 
 	sit->local = addr;
 	sit->sit_mask |= SIT_ATTR_LOCAL;
@@ -484,9 +483,7 @@ int rtnl_link_sit_set_local(struct rtnl_link *link, uint32_t addr)
  */
 uint32_t rtnl_link_sit_get_local(struct rtnl_link *link)
 {
-	struct sit_info *sit = link->l_info;
-
-	IS_SIT_LINK_ASSERT(link);
+	IS_SIT_LINK_ASSERT(link, sit);
 
 	return sit->local;
 }
@@ -500,9 +497,7 @@ uint32_t rtnl_link_sit_get_local(struct rtnl_link *link)
  */
 int rtnl_link_sit_set_remote(struct rtnl_link *link, uint32_t addr)
 {
-	struct sit_info *sit = link->l_info;
-
-	IS_SIT_LINK_ASSERT(link);
+	IS_SIT_LINK_ASSERT(link, sit);
 
 	sit->remote = addr;
 	sit->sit_mask |= SIT_ATTR_REMOTE;
@@ -518,9 +513,7 @@ int rtnl_link_sit_set_remote(struct rtnl_link *link, uint32_t addr)
  */
 uint32_t rtnl_link_sit_get_remote(struct rtnl_link *link)
 {
-	struct sit_info *sit = link->l_info;
-
-	IS_SIT_LINK_ASSERT(link);
+	IS_SIT_LINK_ASSERT(link, sit);
 
 	return sit->remote;
 }
@@ -534,9 +527,7 @@ uint32_t rtnl_link_sit_get_remote(struct rtnl_link *link)
  */
 int rtnl_link_sit_set_ttl(struct rtnl_link *link, uint8_t ttl)
 {
-	struct sit_info *sit = link->l_info;
-
-	IS_SIT_LINK_ASSERT(link);
+	IS_SIT_LINK_ASSERT(link, sit);
 
 	sit->ttl = ttl;
 	sit->sit_mask |= SIT_ATTR_TTL;
@@ -552,9 +543,7 @@ int rtnl_link_sit_set_ttl(struct rtnl_link *link, uint8_t ttl)
  */
 uint8_t rtnl_link_sit_get_ttl(struct rtnl_link *link)
 {
-	struct sit_info *sit = link->l_info;
-
-	IS_SIT_LINK_ASSERT(link);
+	IS_SIT_LINK_ASSERT(link, sit);
 
 	return sit->ttl;
 }
@@ -568,9 +557,7 @@ uint8_t rtnl_link_sit_get_ttl(struct rtnl_link *link)
  */
 int rtnl_link_sit_set_tos(struct rtnl_link *link, uint8_t tos)
 {
-	struct sit_info *sit = link->l_info;
-
-	IS_SIT_LINK_ASSERT(link);
+	IS_SIT_LINK_ASSERT(link, sit);
 
 	sit->tos = tos;
 	sit->sit_mask |= SIT_ATTR_TOS;
@@ -586,9 +573,7 @@ int rtnl_link_sit_set_tos(struct rtnl_link *link, uint8_t tos)
  */
 uint8_t rtnl_link_sit_get_tos(struct rtnl_link *link)
 {
-	struct sit_info *sit = link->l_info;
-
-	IS_SIT_LINK_ASSERT(link);
+	IS_SIT_LINK_ASSERT(link, sit);
 
 	return sit->tos;
 }
@@ -602,9 +587,7 @@ uint8_t rtnl_link_sit_get_tos(struct rtnl_link *link)
  */
 int rtnl_link_sit_set_pmtudisc(struct rtnl_link *link, uint8_t pmtudisc)
 {
-	struct sit_info *sit = link->l_info;
-
-	IS_SIT_LINK_ASSERT(link);
+	IS_SIT_LINK_ASSERT(link, sit);
 
 	sit->pmtudisc = pmtudisc;
 	sit->sit_mask |= SIT_ATTR_PMTUDISC;
@@ -620,9 +603,7 @@ int rtnl_link_sit_set_pmtudisc(struct rtnl_link *link, uint8_t pmtudisc)
  */
 uint8_t rtnl_link_sit_get_pmtudisc(struct rtnl_link *link)
 {
-	struct sit_info *sit = link->l_info;
-
-	IS_SIT_LINK_ASSERT(link);
+	IS_SIT_LINK_ASSERT(link, sit);
 
 	return sit->pmtudisc;
 }
@@ -636,9 +617,7 @@ uint8_t rtnl_link_sit_get_pmtudisc(struct rtnl_link *link)
  */
 int rtnl_link_sit_set_flags(struct rtnl_link *link, uint16_t flags)
 {
-	struct sit_info *sit = link->l_info;
-
-	IS_SIT_LINK_ASSERT(link);
+	IS_SIT_LINK_ASSERT(link, sit);
 
 	sit->flags = flags;
 	sit->sit_mask |= SIT_ATTR_FLAGS;
@@ -654,9 +633,7 @@ int rtnl_link_sit_set_flags(struct rtnl_link *link, uint16_t flags)
  */
 uint16_t rtnl_link_sit_get_flags(struct rtnl_link *link)
 {
-	struct sit_info *sit = link->l_info;
-
-	IS_SIT_LINK_ASSERT(link);
+	IS_SIT_LINK_ASSERT(link, sit);
 
 	return sit->flags;
 }
@@ -670,9 +647,7 @@ uint16_t rtnl_link_sit_get_flags(struct rtnl_link *link)
  */
 int rtnl_link_sit_set_proto(struct rtnl_link *link, uint8_t proto)
 {
-	struct sit_info *sit = link->l_info;
-
-	IS_SIT_LINK_ASSERT(link);
+	IS_SIT_LINK_ASSERT(link, sit);
 
 	sit->proto = proto;
 	sit->sit_mask |= SIT_ATTR_PROTO;
@@ -688,9 +663,7 @@ int rtnl_link_sit_set_proto(struct rtnl_link *link, uint8_t proto)
  */
 uint8_t rtnl_link_sit_get_proto(struct rtnl_link *link)
 {
-	struct sit_info *sit = link->l_info;
-
-	IS_SIT_LINK_ASSERT(link);
+	IS_SIT_LINK_ASSERT(link, sit);
 
 	return sit->proto;
 }