Allow mysqladmin to call COM_SHUTDOWN for 5.6 servers

Summary: Because we skipped 5.7, there was no longer any compatibility code that allows clients to call COM_SHUTDOWN for 5.6 servers. Add it back in until we have finished upgrading all servers to 8.0.

Differential Revision: D12984296

Author: lth

client/mysqladmin.cc

@@ -718,7 +718,7 @@ static int execute_commands(MYSQL *mysql, int argc, char **argv) {
             !stat(pidfile, &pidfile_status))
           last_modified = pidfile_status.st_mtime;
 
-        if (mysql_query(mysql, "shutdown")) {
+        if (mysql_shutdown(mysql, SHUTDOWN_DEFAULT)) {
           my_printf_error(0, "shutdown failed; error: '%s'", error_flags,
                           mysql_error(mysql));
           return -1;

libmysql/libmysql.cc

@@ -797,10 +797,11 @@ MYSQL_RES *STDCALL mysql_list_processes(MYSQL *mysql) {
 }
 
 int STDCALL mysql_shutdown(MYSQL *mysql,
-                           enum mysql_enum_shutdown_level shutdown_level
-                           [[maybe_unused]]) {
+                           enum mysql_enum_shutdown_level shutdown_level) {
+  uchar level[1];
+  level[0] = (uchar)shutdown_level;
   if (mysql_get_server_version(mysql) < 50709)
-    return simple_command(mysql, COM_DEPRECATED_1, nullptr, 0, 0);
+    return simple_command(mysql, COM_DEPRECATED_1, level, 1, 0);
   else
     return mysql_real_query(mysql, STRING_WITH_LEN("shutdown"));
 }