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mariadb/sql/sql_parse.h
Dmitry Shulga 259e5243fa MDEV-24860: Incorrect behaviour of SET STATEMENT in case it is executed as a prepared statement 
Running statements with SET STATEMENT FOR clause is handled incorrectly in
case the whole statement is executed in prepared statement mode.
For example, running of the following statement
  SET STATEMENT sql_mode = 'NO_ENGINE_SUBSTITUTION' FOR CREATE TABLE t1 AS SELECT CONCAT('abc') AS c1;
results in different definition of the table t1 depending on whether
the statement is executed as a prepared or as a regular statement.

In first case the column c1 is defined as
  `c1` varchar(3) DEFAULT NULL
in the last case the column c1 is defined as
  `c1` varchar(3) NOT NULL

Different definition for the column c1 arise due to the fact that
a value of the data memeber Item_func_concat::maybe_null depends on
whether strict mode is on or off. Below is definition of the method
fix_fields() of the class Item_str_func that is base class for the
class Item_func_concat that is created on parsing the
SET STATEMENT FOR clause.

bool Item_str_func::fix_fields(THD *thd, Item **ref)
{
  bool res= Item_func::fix_fields(thd, ref);
  /*
    In Item_str_func::check_well_formed_result() we may set null_value
    flag on the same condition as in test() below.
  */
  maybe_null= maybe_null || thd->is_strict_mode();
  return res;
}

Although the clause SET STATEMENT sql_mode = 'NO_ENGINE_SUBSTITUTION' FOR
is parsed on PREPARE phase during processing of the prepared statement,
real setting of the sql_mode system variable is done on EXECUTION phase.
On the other hand, the method Item_str_func::fix_fields is called on PREPARE
phase. In result, thd->is_strict_mode() returns true during calling the method
Item_str_func::fix_fields(), the data member maybe_null is assigned the value
true and column c1 is defined as DEFAULT NULL.

To fix the issue the system variables listed in the SET STATEMENT FOR clause
are set at the beginning of handling the PREPARE phase just right before
calling  the function check_prepared_statement() and their original values
restored immediate after return from this function.

Additionally, to avoid code duplication the source code used in the function
mysql_execute_command for setting variables, specified by SET STATEMENT
clause, were extracted to the standalone functions
run_set_statement_if_requested(). This new function is called from
the function  mysql_execute_command() and the method
Prepared_statement::prepare().
2021-02-25 14:36:09 +07:00

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/* Copyright (c) 2006, 2011, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */
#ifndef SQL_PARSE_INCLUDED
#define SQL_PARSE_INCLUDED
#include "my_global.h" /* NO_EMBEDDED_ACCESS_CHECKS */
#include "sql_acl.h" /* GLOBAL_ACLS */
class Comp_creator;
class Item;
class Object_creation_ctx;
class Parser_state;
struct TABLE_LIST;
class THD;
class Table_ident;
struct LEX;
enum enum_mysql_completiontype {
ROLLBACK_RELEASE=-2, ROLLBACK=1, ROLLBACK_AND_CHAIN=7,
COMMIT_RELEASE=-1, COMMIT=0, COMMIT_AND_CHAIN=6
};
extern "C" int path_starts_from_data_home_dir(const char *dir);
int test_if_data_home_dir(const char *dir);
int error_if_data_home_dir(const char *path, const char *what);
my_bool net_allocate_new_packet(NET *net, void *thd, uint my_flags);
bool multi_update_precheck(THD *thd, TABLE_LIST *tables);
bool multi_delete_precheck(THD *thd, TABLE_LIST *tables);
int mysql_multi_update_prepare(THD *thd);
int mysql_multi_delete_prepare(THD *thd);
bool mysql_insert_select_prepare(THD *thd);
bool update_precheck(THD *thd, TABLE_LIST *tables);
bool delete_precheck(THD *thd, TABLE_LIST *tables);
bool insert_precheck(THD *thd, TABLE_LIST *tables);
bool create_table_precheck(THD *thd, TABLE_LIST *tables,
TABLE_LIST *create_table);
bool check_fk_parent_table_access(THD *thd,
HA_CREATE_INFO *create_info,
Alter_info *alter_info,
const char* create_db);
bool parse_sql(THD *thd, Parser_state *parser_state,
Object_creation_ctx *creation_ctx, bool do_pfs_digest=false);
void free_items(Item *item);
void cleanup_items(Item *item);
Comp_creator *comp_eq_creator(bool invert);
Comp_creator *comp_ge_creator(bool invert);
Comp_creator *comp_gt_creator(bool invert);
Comp_creator *comp_le_creator(bool invert);
Comp_creator *comp_lt_creator(bool invert);
Comp_creator *comp_ne_creator(bool invert);
int prepare_schema_table(THD *thd, LEX *lex, Table_ident *table_ident,
enum enum_schema_tables schema_table_idx);
void get_default_definer(THD *thd, LEX_USER *definer, bool role);
LEX_USER *create_default_definer(THD *thd, bool role);
LEX_USER *create_definer(THD *thd, LEX_STRING *user_name, LEX_STRING *host_name);
LEX_USER *get_current_user(THD *thd, LEX_USER *user, bool lock=true);
bool sp_process_definer(THD *thd);
bool check_string_byte_length(LEX_STRING *str, uint err_msg,
uint max_byte_length);
bool check_string_char_length(LEX_STRING *str, uint err_msg,
uint max_char_length, CHARSET_INFO *cs,
bool no_error);
bool check_ident_length(LEX_STRING *ident);
CHARSET_INFO* merge_charset_and_collation(CHARSET_INFO *cs, CHARSET_INFO *cl);
CHARSET_INFO *find_bin_collation(CHARSET_INFO *cs);
bool check_host_name(LEX_STRING *str);
bool check_identifier_name(LEX_STRING *str, uint max_char_length,
uint err_code, const char *param_for_err_msg);
bool mysql_test_parse_for_slave(THD *thd,char *inBuf,uint length);
bool sqlcom_can_generate_row_events(const THD *thd);
bool stmt_causes_implicit_commit(THD *thd, uint mask);
bool is_update_query(enum enum_sql_command command);
bool is_log_table_write_query(enum enum_sql_command command);
bool alloc_query(THD *thd, const char *packet, uint packet_length);
void mysql_init_select(LEX *lex);
void mysql_parse(THD *thd, char *rawbuf, uint length,
Parser_state *parser_state, bool is_com_multi,
bool is_next_command);
bool mysql_new_select(LEX *lex, bool move_down);
void create_select_for_variable(const char *var_name);
void create_table_set_open_action_and_adjust_tables(LEX *lex);
void mysql_init_multi_delete(LEX *lex);
bool multi_delete_set_locks_and_link_aux_tables(LEX *lex);
void create_table_set_open_action_and_adjust_tables(LEX *lex);
pthread_handler_t handle_bootstrap(void *arg);
bool run_set_statement_if_requested(THD *thd, LEX *lex);
int mysql_execute_command(THD *thd);
bool do_command(THD *thd);
void do_handle_bootstrap(THD *thd);
bool dispatch_command(enum enum_server_command command, THD *thd,
char* packet, uint packet_length,
bool is_com_multi, bool is_next_command);
void log_slow_statement(THD *thd);
bool append_file_to_dir(THD *thd, const char **filename_ptr,
const char *table_name);
bool append_file_to_dir(THD *thd, const char **filename_ptr,
const char *table_name);
void execute_init_command(THD *thd, LEX_STRING *init_command,
mysql_rwlock_t *var_lock);
bool add_to_list(THD *thd, SQL_I_List<ORDER> &list, Item *group, bool asc);
void add_join_on(THD *thd, TABLE_LIST *b, Item *expr);
void add_join_natural(TABLE_LIST *a,TABLE_LIST *b,List<String> *using_fields,
SELECT_LEX *lex);
bool add_proc_to_list(THD *thd, Item *item);
bool push_new_name_resolution_context(THD *thd,
TABLE_LIST *left_op,
TABLE_LIST *right_op);
void init_update_queries(void);
bool check_simple_select();
Item *normalize_cond(THD *thd, Item *cond);
Item *negate_expression(THD *thd, Item *expr);
bool check_stack_overrun(THD *thd, long margin, uchar *dummy);
/* Variables */
extern const char* any_db;
extern uint sql_command_flags[];
extern uint server_command_flags[];
extern const LEX_STRING command_name[];
extern uint server_command_flags[];
/* Inline functions */
inline bool check_identifier_name(LEX_STRING *str, uint err_code)
{
return check_identifier_name(str, NAME_CHAR_LEN, err_code, "");
}
inline bool check_identifier_name(LEX_STRING *str)
{
return check_identifier_name(str, NAME_CHAR_LEN, 0, "");
}
#ifndef NO_EMBEDDED_ACCESS_CHECKS
bool check_one_table_access(THD *thd, ulong privilege, TABLE_LIST *tables);
bool check_single_table_access(THD *thd, ulong privilege,
TABLE_LIST *tables, bool no_errors);
bool check_routine_access(THD *thd,ulong want_access,char *db,char *name,
bool is_proc, bool no_errors);
bool check_some_access(THD *thd, ulong want_access, TABLE_LIST *table);
bool check_some_routine_access(THD *thd, const char *db, const char *name, bool is_proc);
bool check_table_access(THD *thd, ulong requirements,TABLE_LIST *tables,
bool any_combination_of_privileges_will_do,
uint number,
bool no_errors);
#else
inline bool check_one_table_access(THD *thd, ulong privilege, TABLE_LIST *tables)
{ return false; }
inline bool check_single_table_access(THD *thd, ulong privilege,
TABLE_LIST *tables, bool no_errors)
{ return false; }
inline bool check_routine_access(THD *thd,ulong want_access,char *db,
char *name, bool is_proc, bool no_errors)
{ return false; }
inline bool check_some_access(THD *thd, ulong want_access, TABLE_LIST *table)
{
table->grant.privilege= want_access;
return false;
}
inline bool check_some_routine_access(THD *thd, const char *db,
const char *name, bool is_proc)
{ return false; }
inline bool
check_table_access(THD *thd, ulong requirements,TABLE_LIST *tables,
bool any_combination_of_privileges_will_do,
uint number,
bool no_errors)
{ return false; }
#endif /*NO_EMBEDDED_ACCESS_CHECKS*/
#endif /* SQL_PARSE_INCLUDED */
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