sd-netlink: don't access type->type_system[_union] directly

Make sure we never access type->type_system or type->type_system_union
directly. This is an implementation detail of the type-system and we
should always use the accessors. Right now, they only exist for 2-level
accesses (type-system to type-system). This patch introduces the 1-level
accessors (type to type-system) and makes use of it.

This patch makes sure the proper assertions are in place, so we never
accidentally access sub-type-systems for non-nested/union types.

Note that this places hard-asserts on the accessors. This should be fine,
as we expect callers to only access sub type-systems if they *know*
they're dealing with nested types.

1 files changed, 20 insertions, 10 deletions

diff --git a/src/libsystemd/sd-netlink/netlink-types.c b/src/libsystemd/sd-netlink/netlink-types.c
index 72799da887..fe9e5f9826 100644
--- a/src/libsystemd/sd-netlink/netlink-types.c
+++ b/src/libsystemd/sd-netlink/netlink-types.c
@@ -460,6 +460,24 @@ const NLTypeSystem rtnl_type_system = {
         .types = rtnl_types,
 };
 
+void type_get_type_system(const NLType *nl_type, const NLTypeSystem **ret) {
+        assert(nl_type);
+        assert(ret);
+        assert(nl_type->type == NETLINK_TYPE_NESTED);
+        assert(nl_type->type_system);
+
+        *ret = nl_type->type_system;
+}
+
+void type_get_type_system_union(const NLType *nl_type, const NLTypeSystemUnion **ret) {
+        assert(nl_type);
+        assert(ret);
+        assert(nl_type->type == NETLINK_TYPE_UNION);
+        assert(nl_type->type_system_union);
+
+        *ret = nl_type->type_system_union;
+}
+
 int type_system_get_type(const NLTypeSystem *type_system, const NLType **ret, uint16_t type) {
         const NLType *nl_type;
 
@@ -493,11 +511,7 @@ int type_system_get_type_system(const NLTypeSystem *type_system, const NLTypeSys
         if (r < 0)
                 return r;
 
-        assert(nl_type->type == NETLINK_TYPE_NESTED);
-        assert(nl_type->type_system);
-
-        *ret = nl_type->type_system;
-
+        type_get_type_system(nl_type, ret);
         return 0;
 }
 
@@ -511,11 +525,7 @@ int type_system_get_type_system_union(const NLTypeSystem *type_system, const NLT
         if (r < 0)
                 return r;
 
-        assert(nl_type->type == NETLINK_TYPE_UNION);
-        assert(nl_type->type_system_union);
-
-        *ret = nl_type->type_system_union;
-
+        type_get_type_system_union(nl_type, ret);
         return 0;
 }