Allow to pass multiple group values to membership functions

Instead of calling the membership functions several times it is
helpfull to extend the API and make the single group functions a
special case.

The value 0 (NFNLGRP_NONE) terminates this list.

Example use:

  nl_socket_add_memberships(sock, group_1, group_2, 0);
  nl_socket_drop_memberships(sock, group_1, group_2, 0);

Signed-off-by: Holger Eitzenberger <holger@eitzenberger.org>

2 files changed, 54 insertions, 20 deletions

diff --git a/include/netlink/socket.h b/include/netlink/socket.h
index c10bc2a..5eefa08 100644
--- a/include/netlink/socket.h
+++ b/include/netlink/socket.h
@@ -30,12 +30,20 @@ extern uint32_t			nl_socket_get_local_port(struct nl_sock *);
 extern void			nl_socket_set_local_port(struct nl_sock *,
 							 uint32_t);
 
-extern int			nl_socket_add_membership(struct nl_sock *,
-							 int);
-extern int			nl_socket_drop_membership(struct nl_sock *,
-							  int);
+extern int			nl_socket_add_memberships(struct nl_sock *,
+							 int, ...);
+extern int			nl_socket_drop_memberships(struct nl_sock *,
+							  int, ...);
 extern void			nl_join_groups(struct nl_sock *, int);
 
+static inline int nl_socket_add_membership(struct nl_sock *sk, int group) {
+	return nl_socket_add_memberships(sk, group, 0);
+}
+
+static inline int nl_socket_drop_membership(struct nl_sock *sk, int group) {
+	return nl_socket_drop_memberships(sk, group, 0);
+}
+
 extern uint32_t			nl_socket_get_peer_port(struct nl_sock *);
 extern void			nl_socket_set_peer_port(struct nl_sock *,
 							uint32_t);
diff --git a/lib/socket.c b/lib/socket.c
index 1a11971..511eb14 100644
--- a/lib/socket.c
+++ b/lib/socket.c
@@ -345,13 +345,14 @@ void nl_socket_set_local_port(struct nl_sock *sk, uint32_t port)
  */
 
 /**
- * Join a group
+ * Join groups
  * @arg sk		Netlink socket
  * @arg group		Group identifier
  *
- * Joins the specified group using the modern socket option which
+ * Joins the specified groups using the modern socket option which
  * is available since kernel version 2.6.14. It allows joining an
- * almost arbitary number of groups without limitation.
+ * almost arbitary number of groups without limitation.  The list
+ * of groups has to be terminated by 0 (%NFNLGRP_NONE).
  *
  * Make sure to use the correct group definitions as the older
  * bitmask definitions for nl_join_groups() are likely to still
@@ -359,43 +360,68 @@ void nl_socket_set_local_port(struct nl_sock *sk, uint32_t port)
  *
  * @return 0 on sucess or a negative error code.
  */
-int nl_socket_add_membership(struct nl_sock *sk, int group)
+int nl_socket_add_memberships(struct nl_sock *sk, int group, ...)
 {
 	int err;
+	va_list ap;
 
 	if (sk->s_fd == -1)
 		return -NLE_BAD_SOCK;
 
-	err = setsockopt(sk->s_fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP,
-			 &group, sizeof(group));
-	if (err < 0)
-		return -nl_syserr2nlerr(errno);
+	va_start(ap, group);
+
+	while (group != 0) {
+		if (group < 0)
+			return -NLE_INVAL;
+
+		err = setsockopt(sk->s_fd, SOL_NETLINK, NETLINK_ADD_MEMBERSHIP,
+						 &group, sizeof(group));
+		if (err < 0)
+			return -nl_syserr2nlerr(errno);
+
+		group = va_arg(ap, int);
+	}
+
+	va_end(ap);
 
 	return 0;
 }
 
 /**
- * Leave a group
+ * Leave groups
  * @arg sk		Netlink socket
  * @arg group		Group identifier
  *
- * Leaves the specified group using the modern socket option
- * which is available since kernel version 2.6.14.
+ * Leaves the specified groups using the modern socket option
+ * which is available since kernel version 2.6.14. The list of groups
+ * has to terminated by 0 (%NFNLGRP_NONE).
  *
  * @see nl_socket_add_membership
  * @return 0 on success or a negative error code.
  */
-int nl_socket_drop_membership(struct nl_sock *sk, int group)
+int nl_socket_drop_memberships(struct nl_sock *sk, int group, ...)
 {
 	int err;
+	va_list ap;
 
 	if (sk->s_fd == -1)
 		return -NLE_BAD_SOCK;
 
-	err = setsockopt(sk->s_fd, SOL_NETLINK, NETLINK_DROP_MEMBERSHIP,
-			 &group, sizeof(group));
-	if (err < 0)
-		return -nl_syserr2nlerr(errno);
+	va_start(ap, group);
+
+	while (group != 0) {
+		if (group < 0)
+			return -NLE_INVAL;
+
+		err = setsockopt(sk->s_fd, SOL_NETLINK, NETLINK_DROP_MEMBERSHIP,
+						 &group, sizeof(group));
+		if (err < 0)
+			return -nl_syserr2nlerr(errno);
+
+		group = va_arg(ap, int);
+	}
+
+	va_end(ap);
 
 	return 0;
 }