+#define blob_for_each_attr_len(pos, attr, attr_len, rem) \
+ for (rem = attr ? blob_len(attr) : 0, \
+ pos = (struct blob_attr *) (attr ? blob_data(attr) : NULL); \
+ rem >= sizeof(struct blob_attr) && rem < attr_len && (blob_pad_len(pos) <= rem) && \
+ (blob_pad_len(pos) >= sizeof(struct blob_attr)); \
+ rem -= blob_pad_len(pos), pos = blob_next(pos))