Fix control flow and T_BEGIN/T_END hygiene

You mustn't goto, break, continue, or return from out of a
T_BEGIN {...} T_END block, as that will lose a t_pop().
This has been seen in the wild: Panic: Leaked t_pop() call

Signed-off-by: Phil Carmody <phil@dovecot.fi>

src/director/login-connection.c

@@ -73,21 +73,27 @@ static void login_connection_input(struct login_connection *conn)
 
 static void login_connection_authreply_input(struct login_connection *conn)
 {
+	bool bail = FALSE;
 	const char *line;
 
-	while ((line = i_stream_read_next_line(conn->input)) != NULL) T_BEGIN {
+	while (!bail && (line = i_stream_read_next_line(conn->input)) != NULL) T_BEGIN {
 		if (!conn->handshaked) {
 			if (!version_string_verify(line, "director-authreply-client",
 						   AUTHREPLY_PROTOCOL_MAJOR_VERSION)) {
 				i_error("authreply client sent invalid handshake: %s", line);
 				login_connection_deinit(&conn);
-				return;
+				bail = TRUE; /* don't return from within a T_BEGIN {...} T_END */
+			} else {
+				conn->handshaked = TRUE;
 			}
-			conn->handshaked = TRUE;
 		} else {
 			auth_input_line(line, conn);
 		}
 	} T_END;
+
+	if (bail)
+		return;
+
 	if (conn->input->eof) {
 		if (conn->input->stream_errno != 0 &&
 		    conn->input->stream_errno != ECONNRESET) {

src/lib/file-lock.c

@@ -114,9 +114,9 @@ file_lock_find_proc_locks(int lock_fd ATTR_UNUSED)
 
 		/* number: FLOCK/POSIX ADVISORY READ/WRITE pid
 		   major:minor:inode region-start region-end */
-		if (str_array_length(args) < 8)
-			continue;
-		if (strcmp(args[5], node_buf) == 0) {
+		if (str_array_length(args) < 8) {
+			; /* don't continue from within a T_BEGIN {...} T_END */
+		} else if (strcmp(args[5], node_buf) == 0) {
 			lock_type = strcmp(args[3], "READ") == 0 ?
 				"READ" : "WRITE";
 			if (str_to_pid(args[4], &pid) < 0)