[sheepdog] [PATCH 2/2] sheep: fix error handling in local_stat_cluster

[Christoph Hellwig]

Error out and print a debug message if epoch_log_read_remote doesn't manage
to return a node list.  Without this we touch possibly uninitialized memory
in get_max_nr_copies_from.

Signed-off-by: Christoph Hellwig <hch at lst.de>

diff --git a/sheep/ops.c b/sheep/ops.c
index a6f0670..27ca07d 100644
--- a/sheep/ops.c
+++ b/sheep/ops.c
@@ -351,10 +351,16 @@ static int local_stat_cluster(struct request *req)
 		log->ctime = get_cluster_ctime();
 		log->nr_nodes = epoch_log_read(epoch, (char *)log->nodes,
 					       sizeof(log->nodes));
-		if (log->nr_nodes == -1)
+		if (log->nr_nodes == -1) {
 			log->nr_nodes = epoch_log_read_remote(epoch,
 							      (char *)log->nodes,
 							      sizeof(log->nodes));
+		}
+		if (log->nr_nodes == -1) {
+			eprintf("Failed to read log for epoch %d\n", i);
+			break;
+		}
+
 		log->nr_copies = get_max_nr_copies_from(log->nodes, log->nr_nodes);
 
 		rsp->data_length += sizeof(*log);