pg_upgrade: shut down server after auth failure

Register atexit() server shutdown if pg_ctl successfully started the
server, but we can't connect to it.

Backpatch to 9.3.

Pavel Raiskup

contrib/pg_upgrade/server.c

@@ -166,7 +166,6 @@ static void
 stop_postmaster_atexit(void)
 {
 	stop_postmaster(true);
-
 }
 
 
@@ -236,10 +235,34 @@ start_postmaster(ClusterInfo *cluster, bool throw_error)
 							  false,
 							  "%s", cmd);
 
+	/* Did it fail and we are just testing if the server could be started? */
 	if (!pg_ctl_return && !throw_error)
 		return false;
 
-	/* Check to see if we can connect to the server; if not, report it. */
+	/*
+	 * We set this here to make sure atexit() shuts down the server,
+	 * but only if we started the server successfully.  We do it
+	 * before checking for connectivity in case the server started but
+	 * there is a connectivity failure.  If pg_ctl did not return success,
+	 * we will exit below.
+	 *
+	 * Pre-9.1 servers do not have PQping(), so we could be leaving the server
+	 * running if authentication was misconfigured, so someday we might went to
+	 * be more aggressive about doing server shutdowns even if pg_ctl fails,
+	 * but now (2013-08-14) it seems prudent to be cautious.  We don't want to
+	 * shutdown a server that might have been accidentally started during the
+	 * upgrade.
+	 */
+	if (pg_ctl_return)
+		os_info.running_cluster = cluster;
+
+	/*
+	 * pg_ctl -w might have failed because the server couldn't be started,
+	 * or there might have been a connection problem in _checking_ if the
+	 * server has started.  Therefore, even if pg_ctl failed, we continue
+	 * and test for connectivity in case we get a connection reason for the
+	 * failure.
+	 */
 	if ((conn = get_db_conn(cluster, "template1")) == NULL ||
 		PQstatus(conn) != CONNECTION_OK)
 	{
@@ -253,13 +276,14 @@ start_postmaster(ClusterInfo *cluster, bool throw_error)
 	}
 	PQfinish(conn);
 
-	/* If the connection didn't fail, fail now */
+	/*
+	 * If pg_ctl failed, and the connection didn't fail, and throw_error is
+	 * enabled, fail now.  This could happen if the server was already running.
+	 */
 	if (!pg_ctl_return)
 		pg_log(PG_FATAL, "pg_ctl failed to start the %s server, or connection failed\n",
 			   CLUSTER_NAME(cluster));
 
-	os_info.running_cluster = cluster;
-
 	return true;
 }