Bug #34739 unexpected binlog file name when --log-bin is set to a directory name

If --log-bin is set to a directory name with the trailing 'FN_LIBCHAR', 
which will be '/' on Unix like systems, and '\\' on Windows like systems. 
the basename of the binlog is empty so that the created files named 
'.000001' and '.index'. It is not expected. 
The same thing happened to --log-bin-index, --relay-log and 
--relay-log-index options.

To resolve the problem, in these cases the program should report an error 
and abort.

sql/mysqld.cc

@@ -3888,6 +3888,27 @@ server.");
 
   if (opt_bin_log)
   {
+    /* Reports an error and aborts, if the --log-bin's path 
+       is a directory.*/
+    if (opt_bin_logname && 
+        opt_bin_logname[strlen(opt_bin_logname) - 1] == FN_LIBCHAR)
+    {
+      sql_print_error("Path '%s' is a directory name, please specify \
+a file name for --log-bin option", opt_bin_logname);
+      unireg_abort(1);
+    }
+
+    /* Reports an error and aborts, if the --log-bin-index's path 
+       is a directory.*/
+    if (opt_binlog_index_name && 
+        opt_binlog_index_name[strlen(opt_binlog_index_name) - 1] 
+        == FN_LIBCHAR)
+    {
+      sql_print_error("Path '%s' is a directory name, please specify \
+a file name for --log-bin-index option", opt_binlog_index_name);
+      unireg_abort(1);
+    }
+
     char buf[FN_REFLEN];
     const char *ln;
     ln= mysql_bin_log.generate_name(opt_bin_logname, "-bin", 1, buf);

sql/rpl_rli.cc

@@ -132,6 +132,29 @@ int init_relay_log_info(Relay_log_info* rli,
     rli->relay_log.max_size (and mysql_bin_log.max_size).
   */
   {
+    /* Reports an error and returns, if the --relay-log's path 
+       is a directory.*/
+    if (opt_relay_logname && 
+        opt_relay_logname[strlen(opt_relay_logname) - 1] == FN_LIBCHAR)
+    {
+      pthread_mutex_unlock(&rli->data_lock);
+      sql_print_error("Path '%s' is a directory name, please specify \
+a file name for --relay-log option", opt_relay_logname);
+      DBUG_RETURN(1);
+    }
+
+    /* Reports an error and returns, if the --relay-log-index's path 
+       is a directory.*/
+    if (opt_relaylog_index_name && 
+        opt_relaylog_index_name[strlen(opt_relaylog_index_name) - 1] 
+        == FN_LIBCHAR)
+    {
+      pthread_mutex_unlock(&rli->data_lock);
+      sql_print_error("Path '%s' is a directory name, please specify \
+a file name for --relay-log-index option", opt_relaylog_index_name);
+      DBUG_RETURN(1);
+    }
+
     char buf[FN_REFLEN];
     const char *ln;
     static bool name_warning_sent= 0;