[MDEV-7978] Updated syntax for SHOW CREATE USER

sql/mysqld.cc

@@ -3917,6 +3917,7 @@ SHOW_VAR com_status_vars[]= {
   {"show_create_proc",     STMT_STATUS(SQLCOM_SHOW_CREATE_PROC)},
   {"show_create_table",    STMT_STATUS(SQLCOM_SHOW_CREATE)},
   {"show_create_trigger",  STMT_STATUS(SQLCOM_SHOW_CREATE_TRIGGER)},
+  {"show_create_user",     STMT_STATUS(SQLCOM_SHOW_CREATE_USER)},
   {"show_databases",       STMT_STATUS(SQLCOM_SHOW_DATABASES)},
   {"show_engine_logs",     STMT_STATUS(SQLCOM_SHOW_ENGINE_LOGS)},
   {"show_engine_mutex",    STMT_STATUS(SQLCOM_SHOW_ENGINE_MUTEX)},

sql/sp_head.cc

@@ -216,6 +216,7 @@ sp_get_flags_for_command(LEX *lex)
   case SQLCOM_SHOW_CREATE_PROC:
   case SQLCOM_SHOW_CREATE_EVENT:
   case SQLCOM_SHOW_CREATE_TRIGGER:
+  case SQLCOM_SHOW_CREATE_USER:
   case SQLCOM_SHOW_DATABASES:
   case SQLCOM_SHOW_ERRORS:
   case SQLCOM_SHOW_EXPLAIN:

sql/sql_acl.cc

@@ -7733,6 +7733,10 @@ static int show_grants_callback(ACL_USER_BASE *role, void *data)
   return 0;
 }
 
+bool mysql_show_create_user(THD *thd, LEX_USER *lex_user)
+{
+  return FALSE;
+}
 
 void mysql_show_grants_get_fields(THD *thd, List<Item> *fields,
                                   const char *name)

sql/sql_acl.h

@@ -244,6 +244,7 @@ ulong get_column_grant(THD *thd, GRANT_INFO *grant,
 void mysql_show_grants_get_fields(THD *thd, List<Item> *fields,
                                   const char *name);
 bool mysql_show_grants(THD *thd, LEX_USER *user);
+bool mysql_show_create_user(THD *thd, LEX_USER *user);
 int fill_schema_enabled_roles(THD *thd, TABLE_LIST *tables, COND *cond);
 int fill_schema_applicable_roles(THD *thd, TABLE_LIST *tables, COND *cond);
 void get_privilege_desc(char *to, uint max_length, ulong access);

sql/sql_cmd.h

@@ -94,6 +94,7 @@ enum enum_sql_command {
   SQLCOM_COMPOUND,
   SQLCOM_SHOW_GENERIC,
   SQLCOM_ALTER_USER,
+  SQLCOM_SHOW_CREATE_USER,
 
   /*
     When a command is added here, be sure it's also added in mysqld.cc

sql/sql_parse.cc

@@ -417,6 +417,7 @@ void init_update_queries(void)
   sql_command_flags[SQLCOM_SHOW_EXPLAIN]= CF_STATUS_COMMAND;
   sql_command_flags[SQLCOM_SHOW_PROCESSLIST]= CF_STATUS_COMMAND;
   sql_command_flags[SQLCOM_SHOW_GRANTS]=      CF_STATUS_COMMAND;
+  sql_command_flags[SQLCOM_SHOW_CREATE_USER]= CF_STATUS_COMMAND;
   sql_command_flags[SQLCOM_SHOW_CREATE_DB]=   CF_STATUS_COMMAND;
   sql_command_flags[SQLCOM_SHOW_CREATE]=  CF_STATUS_COMMAND;
   sql_command_flags[SQLCOM_SHOW_MASTER_STAT]= CF_STATUS_COMMAND;
@@ -4946,6 +4947,7 @@ mysql_execute_command(THD *thd)
     break;
 
 #ifndef NO_EMBEDDED_ACCESS_CHECKS
+  case SQLCOM_SHOW_CREATE_USER:
   case SQLCOM_SHOW_GRANTS:
   {
     LEX_USER *grant_user= lex->grant_user;
@@ -4962,7 +4964,10 @@ mysql_execute_command(THD *thd)
         grant_user->user.str == current_user_and_current_role.str ||
         !check_access(thd, SELECT_ACL, "mysql", NULL, NULL, 1, 0))
     {
-      res = mysql_show_grants(thd, grant_user);
+      if (lex->sql_command == SQLCOM_SHOW_GRANTS)
+        res = mysql_show_grants(thd, grant_user);
+      else
+        res = mysql_show_create_user(thd, grant_user);
     }
     break;
   }

sql/sql_yacc.yy

@@ -12774,6 +12774,18 @@ show_param:
             lex->sql_command= SQLCOM_SHOW_CREATE_TRIGGER;
             lex->spname= $3;
           }
+        | CREATE USER
+          {
+            Lex->sql_command= SQLCOM_SHOW_CREATE_USER;
+            if (!(Lex->grant_user= (LEX_USER*)thd->alloc(sizeof(LEX_USER))))
+              MYSQL_YYABORT;
+            Lex->grant_user->user= current_user_and_current_role;
+          }
+        | CREATE USER user
+          {
+             Lex->sql_command= SQLCOM_SHOW_CREATE_USER;
+             Lex->grant_user= $3;
+          }
         | PROCEDURE_SYM STATUS_SYM wild_and_where
           {
             LEX *lex= Lex;