For some strange reason, every so often it appears possible for the event library to trip the read event on a socket, yet have the read itself yield an error. If/when that happens, report the error and continue on.

This happens rarely, but it does seem to happen.

This commit was SVN r22398.

orte/mca/rmcast/basic/rmcast_basic.c

@@ -976,6 +976,13 @@ static void recv_handler(int sd, short flags, void* cbdata)
     data = (uint8_t*)malloc(mca_rmcast_basic_component.max_msg_size * sizeof(uint8_t));
     sz = read(sd, data, mca_rmcast_basic_component.max_msg_size);
     
+    if (sz <= 0) {
+        /* this shouldn't happen - report the errno */
+        opal_output(0, "%s Error on multicast recv socket event: %s(%d)",
+                    ORTE_NAME_PRINT(ORTE_PROC_MY_NAME), strerror(errno), errno);
+        return;
+    }
+    
     OPAL_OUTPUT_VERBOSE((2, orte_rmcast_base.rmcast_output,
                          "%s rmcast:basic recvd %d bytes from channel %d",
                          ORTE_NAME_PRINT(ORTE_PROC_MY_NAME),