netlink: add nla_policy_len()
It calculates the max. length of a Netlink policy, which is usefull
for allocating Netlink buffers roughly the size of the actual
message.
Signed-off-by: Holger Eitzenberger <holger@eitzenberger.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/netlink/attr.c b/net/netlink/attr.c
index 56c3ce7..ae32c57 100644
--- a/net/netlink/attr.c
+++ b/net/netlink/attr.c
@@ -133,6 +133,32 @@
}
/**
+ * nla_policy_len - Determin the max. length of a policy
+ * @policy: policy to use
+ * @n: number of policies
+ *
+ * Determines the max. length of the policy. It is currently used
+ * to allocated Netlink buffers roughly the size of the actual
+ * message.
+ *
+ * Returns 0 on success or a negative error code.
+ */
+int
+nla_policy_len(const struct nla_policy *p, int n)
+{
+ int i, len = 0;
+
+ for (i = 0; i < n; i++) {
+ if (p->len)
+ len += nla_total_size(p->len);
+ else if (nla_attr_minlen[p->type])
+ len += nla_total_size(nla_attr_minlen[p->type]);
+ }
+
+ return len;
+}
+
+/**
* nla_parse - Parse a stream of attributes into a tb buffer
* @tb: destination array with maxtype+1 elements
* @maxtype: maximum attribute type to be expected
@@ -456,6 +482,7 @@
}
EXPORT_SYMBOL(nla_validate);
+EXPORT_SYMBOL(nla_policy_len);
EXPORT_SYMBOL(nla_parse);
EXPORT_SYMBOL(nla_find);
EXPORT_SYMBOL(nla_strlcpy);