[PATCH nft v2 2/2] Handle retriable errors from mnl functions

[Eugene Crosser <crosser@average.org>]

rc == -1 and errno == EINTR mean:

mnl_socket_recvfrom() - blindly rerun the function
mnl_cb_run()          - restart dump request from scratch

This commit introduces handling of both these conditions

Signed-off-by: Eugene Crosser <crosser@average.org>
---
 src/iface.c | 37 ++++++++++++++++++++++++-------------
 1 file changed, 24 insertions(+), 13 deletions(-)

diff --git a/src/iface.c b/src/iface.c
index d0e1834c..5ecc087d 100644
--- a/src/iface.c
+++ b/src/iface.c
@@ -59,14 +59,14 @@ static int data_cb(const struct nlmsghdr *nlh, void *data)
 	return MNL_CB_OK;
 }
 
-void iface_cache_update(void)
+static int __iface_cache_update(void)
 {
 	char buf[MNL_SOCKET_BUFFER_SIZE];
 	struct mnl_socket *nl;
 	struct nlmsghdr *nlh;
 	struct rtgenmsg *rt;
 	uint32_t seq, portid;
-	int ret;
+	int ret = -1;
 
 	nlh = mnl_nlmsg_put_header(buf);
 	nlh->nlmsg_type	= RTM_GETLINK;
@@ -77,28 +77,39 @@ void iface_cache_update(void)
 
 	nl = mnl_socket_open(NETLINK_ROUTE);
 	if (nl == NULL)
-		netlink_init_error();
+		return -1;
 
 	if (mnl_socket_bind(nl, 0, MNL_SOCKET_AUTOPID) < 0)
-		netlink_init_error();
+		goto close_and_return;
 
 	portid = mnl_socket_get_portid(nl);
 
 	if (mnl_socket_sendto(nl, nlh, nlh->nlmsg_len) < 0)
-		netlink_init_error();
+		goto close_and_return;
 
-	ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
-	while (ret > 0) {
-		ret = mnl_cb_run(buf, ret, seq, portid, data_cb, NULL);
-		if (ret <= MNL_CB_STOP)
+	do {
+		do ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
+		while (ret == -1 && errno == EINTR);
+		if (ret == -1)
 			break;
-		ret = mnl_socket_recvfrom(nl, buf, sizeof(buf));
-	}
-	if (ret == -1)
-		netlink_init_error();
+		ret = mnl_cb_run(buf, ret, seq, portid, data_cb, NULL);
+	} while (ret > MNL_CB_STOP);
 
+close_and_return:
 	mnl_socket_close(nl);
 
+	return ret;
+}
+
+void iface_cache_update(void)
+{
+	int ret;
+
+	do ret = __iface_cache_update();
+	while (ret == -1 && errno == EINTR);
+	if (ret == -1)
+		netlink_init_error();
+
 	iface_cache_init = true;
 }
 
-- 
2.32.0