lib: merge implementations of nl_attr_end() and nl_attr_keep_empty()

Both functions are almost identical. Merge them into a common helper
function with an @keep_empty argument, so it is clear at which point
they differ.

Also, fix symbols versioning for nl_attr_keep_empty(). For symbol
versioning, once released a version cannot be modifified/extended.

1 files changed, 18 insertions, 46 deletions

diff --git a/lib/attr.c b/lib/attr.c
index d90fa479..0928630b 100644
--- a/lib/attr.c
+++ b/lib/attr.c
@@ -912,22 +912,14 @@ struct nlattr *nla_nest_start(struct nl_msg *msg, int attrtype)
 	return start;
 }
 
-/**
- * Finalize nesting of attributes.
- * @arg msg		Netlink message.
- * @arg start		Container attribute as returned from nla_nest_start().
- *
- * Corrects the container attribute header to include the appeneded attributes.
- *
- * @return 0 on success or a negative error code.
- */
-int nla_nest_end(struct nl_msg *msg, struct nlattr *start)
+static int _nest_end(struct nl_msg *msg, struct nlattr *start, int keep_empty)
 {
 	size_t pad, len;
 
 	len = (void *) nlmsg_tail(msg->nm_nlh) - (void *) start;
 
-	if (len == NLA_HDRLEN || len > USHRT_MAX) {
+	if (   len > USHRT_MAX
+	    || (!keep_empty && len == NLA_HDRLEN)) {
 		/*
 		 * Max nlattr size exceeded or empty nested attribute, trim the
 		 * attribute header again
@@ -962,6 +954,20 @@ int nla_nest_end(struct nl_msg *msg, struct nlattr *start)
 }
 
 /**
+ * Finalize nesting of attributes.
+ * @arg msg		Netlink message.
+ * @arg start		Container attribute as returned from nla_nest_start().
+ *
+ * Corrects the container attribute header to include the appeneded attributes.
+ *
+ * @return 0 on success or a negative error code.
+ */
+int nla_nest_end(struct nl_msg *msg, struct nlattr *start)
+{
+	return _nest_end (msg, start, 0);
+}
+
+/**
  * Finalize nesting of attributes without stripping off empty attributes.
  * @arg msg		Netlink message.
  * @arg start		Container attribute as returned from nla_nest_start().
@@ -973,41 +979,7 @@ int nla_nest_end(struct nl_msg *msg, struct nlattr *start)
  */
 int nla_nest_end_keep_empty(struct nl_msg *msg, struct nlattr *start)
 {
-	size_t pad, len;
-
-	len = (void *) nlmsg_tail(msg->nm_nlh) - (void *) start;
-
-	if (len > USHRT_MAX) {
-		/*
-		 * Max nlattr size is exceeded, trim the attribute header again
-		 */
-		nla_nest_cancel(msg, start);
-
-		/* Return error only if nlattr size was exceeded */
-		return -NLE_ATTRSIZE;
-	}
-
-	start->nla_len = len;
-
-	pad = NLMSG_ALIGN(msg->nm_nlh->nlmsg_len) - msg->nm_nlh->nlmsg_len;
-	if (pad > 0) {
-		/*
-		 * Data inside attribute does not end at a alignment boundry.
-		 * Pad accordingly and accoun for the additional space in
-		 * the message. nlmsg_reserve() may never fail in this situation,
-		 * the allocate message buffer must be a multiple of NLMSG_ALIGNTO.
-		 */
-		if (!nlmsg_reserve(msg, pad, 0))
-			BUG();
-
-		NL_DBG(2, "msg %p: attr <%p> %d: added %zu bytes of padding\n",
-			msg, start, start->nla_type, pad);
-	}
-
-	NL_DBG(2, "msg %p: attr <%p> %d: closing nesting, len=%u\n",
-		msg, start, start->nla_type, start->nla_len);
-
-	return 0;
+	return _nest_end (msg, start, 1);
 }
 
 /**