percona-server-5.7.36-39/sql/parse_tree_helpers.cc

/* Copyright (c) 2013, 2021, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   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, version 2.0, 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 02110-1301  USA */

#include "my_config.h"
#include "parse_tree_helpers.h"

#include "sql_class.h"
#include "sp_head.h"
#include "sp_instr.h"
#include "auth/auth_common.h"


/**
  Create an object to represent a SP variable in the Item-hierarchy.

  @param thd              The current thread.
  @param name             The SP variable name.
  @param spv              The SP variable (optional).
  @param query_start_ptr  Start of the SQL-statement query string (optional).
  @param start            Start position of the SP variable name in the query.
  @param end              End position of the SP variable name in the query.

  @remark If spv is not specified, the name is used to search for the
          variable in the parse-time context. If the variable does not
          exist, a error is set and NULL is returned to the caller.

  @return An Item_splocal object representing the SP variable, or NULL on error.
*/
Item_splocal* create_item_for_sp_var(THD *thd,
                                     LEX_STRING name,
                                     sp_variable *spv,
                                     const char *query_start_ptr,
                                     const char *start,
                                     const char *end)
{
  LEX *lex= thd->lex;
  size_t spv_pos_in_query= 0;
  size_t spv_len_in_query= 0;
  sp_pcontext *pctx= lex->get_sp_current_parsing_ctx();

  /* If necessary, look for the variable. */
  if (pctx && !spv)
    spv= pctx->find_variable(name, false);

  if (!spv)
  {
    my_error(ER_SP_UNDECLARED_VAR, MYF(0), name.str);
    return NULL;
  }

  assert(pctx && spv);

  if (query_start_ptr)
  {
    /* Position and length of the SP variable name in the query. */
    spv_pos_in_query= start - query_start_ptr;
    spv_len_in_query= end - start;
  }

  Item_splocal *item=
    new (thd->mem_root) Item_splocal(
      name, spv->offset, spv->type, spv_pos_in_query, spv_len_in_query);

#ifndef NDEBUG
  if (item)
    item->m_sp= lex->sphead;
#endif

  return item;
}


/**
   Report syntax error if the sel query block can't be parenthesized

   @return false if successful, true if an error was reported. In the latter
   case parsing should stop.
 */
bool setup_select_in_parentheses(SELECT_LEX *sel)
{
  assert(sel->braces);
  if (sel->linkage == UNION_TYPE &&
      !sel->master_unit()->first_select()->braces &&
      sel->master_unit()->first_select()->linkage ==
      UNION_TYPE)
  {
    my_syntax_error(ER(ER_SYNTAX_ERROR));
    return true;
  }
  if (sel->linkage == UNION_TYPE &&
      sel->olap != UNSPECIFIED_OLAP_TYPE &&
      sel->master_unit()->fake_select_lex)
  {
    my_error(ER_WRONG_USAGE, MYF(0), "CUBE/ROLLUP", "ORDER BY");
    return true;
  }
  return false;
}


/**
  @brief Push an error message into MySQL diagnostic area with line
  and position information.

  This function provides semantic action implementers with a way
  to push the famous "You have a syntax error near..." error
  message into the diagnostic area, which is normally produced only if
  a parse error is discovered internally by the Bison generated
  parser.
*/

void my_syntax_error(const char *s)
{
  THD *thd= current_thd;
  Lex_input_stream *lip= & thd->m_parser_state->m_lip;

  const char *yytext= lip->get_tok_start();
  if (!yytext)
    yytext= "";

  /* Push an error into the diagnostic area */
  ErrConvString err(yytext, thd->variables.character_set_client);
  my_printf_error(ER_PARSE_ERROR,  ER(ER_PARSE_ERROR), MYF(0), s,
                  err.ptr(), lip->yylineno);
}


bool find_sys_var_null_base(THD *thd, struct sys_var_with_base *tmp)
{
  tmp->var= find_sys_var(thd, tmp->base_name.str, tmp->base_name.length);

  if (tmp->var == NULL)
    my_error(ER_UNKNOWN_SYSTEM_VARIABLE, MYF(0), tmp->base_name.str);
  else
    tmp->base_name= null_lex_str;

  return thd->is_error();
}


/**
  Helper action for a SET statement.
  Used to push a system variable into the assignment list.

  @param thd      the current thread
  @param var_with_base  the system variable with base name
  @param var_type the scope of the variable
  @param val      the value being assigned to the variable

  @return TRUE if error, FALSE otherwise.
*/

bool
set_system_variable(THD *thd, struct sys_var_with_base *var_with_base,
                    enum enum_var_type var_type, Item *val)
{
  set_var *var;
  LEX *lex= thd->lex;
  sp_head *sp= lex->sphead;
  sp_pcontext *pctx= lex->get_sp_current_parsing_ctx();

  /* No AUTOCOMMIT from a stored function or trigger. */
  if (pctx && var_with_base->var == Sys_autocommit_ptr)
    sp->m_flags|= sp_head::HAS_SET_AUTOCOMMIT_STMT;

#ifdef HAVE_REPLICATION
  if (lex->uses_stored_routines() &&
      ((var_with_base->var == Sys_gtid_next_ptr
#ifdef HAVE_GTID_NEXT_LIST
       || var_with_base->var == Sys_gtid_next_list_ptr
#endif
       ) ||
       Sys_gtid_purged_ptr == var_with_base->var))
  {
    my_error(ER_SET_STATEMENT_CANNOT_INVOKE_FUNCTION, MYF(0),
             var_with_base->var->name.str);
    return TRUE;
  }
#endif

  if (val && val->type() == Item::FIELD_ITEM &&
      ((Item_field*)val)->table_name)
  {
    my_error(ER_WRONG_TYPE_FOR_VAR, MYF(0), var_with_base->var->name.str);
    return TRUE;
  }

  if (! (var= new set_var(var_type, var_with_base->var,
         &var_with_base->base_name, val)))
    return TRUE;

  return lex->var_list.push_back(var);
}


/**
  Make a new string allocated on THD's mem-root.

  @param thd        thread handler.
  @param start_ptr  start of the new string.
  @param end_ptr    end of the new string.

  @return LEX_STRING object, containing a pointer to a newly
  constructed/allocated string, and its length. The pointer is NULL
  in case of out-of-memory error.
*/
LEX_STRING make_string(THD *thd, const char *start_ptr, const char *end_ptr)
{
  LEX_STRING s;

  s.length= end_ptr - start_ptr;
  s.str= (char *) thd->alloc(s.length + 1);

  if (s.str)
    strmake(s.str, start_ptr, s.length);

  return s;
}


/**
  Helper action for a SET statement.
  Used to SET a field of NEW row.

  @param pc                 the parse context
  @param trigger_field_name the NEW-row field name
  @param expr_item          the value expression being assigned
  @param expr_query         the value expression query

  @return error status (true if error, false otherwise).
*/

bool set_trigger_new_row(Parse_context *pc,
                         LEX_STRING trigger_field_name,
                         Item *expr_item,
                         LEX_STRING expr_query)
{
  THD *thd= pc->thd;
  LEX *lex= thd->lex;
  sp_head *sp= lex->sphead;

  assert(expr_item);
  assert(sp->m_trg_chistics.action_time == TRG_ACTION_BEFORE &&
         (sp->m_trg_chistics.event == TRG_EVENT_INSERT ||
          sp->m_trg_chistics.event == TRG_EVENT_UPDATE));

  Item_trigger_field *trg_fld=
    new (pc->mem_root) Item_trigger_field(POS(),
                                          TRG_NEW_ROW,
                                          trigger_field_name.str,
                                          UPDATE_ACL, false);

  if (trg_fld == NULL || trg_fld->itemize(pc, (Item **) &trg_fld))
    return true;
  assert(trg_fld->type() == Item::TRIGGER_FIELD_ITEM);

  sp_instr_set_trigger_field *i=
    new (pc->mem_root)
      sp_instr_set_trigger_field(sp->instructions(),
                                 lex,
                                 trigger_field_name,
                                 trg_fld, expr_item,
                                 expr_query);

  if (!i)
    return true;

  /*
    Let us add this item to list of all Item_trigger_field
    objects in trigger.
  */
  sp->m_cur_instr_trig_field_items.link_in_list(trg_fld,
                                                &trg_fld->next_trg_field);

  return sp->add_instr(thd, i);
}


void sp_create_assignment_lex(THD *thd, const char *option_ptr)
{
  sp_head *sp= thd->lex->sphead;

  /*
    We can come here in the following cases:

      1. it's a regular SET statement outside stored programs
        (thd->lex->sphead is NULL);

      2. we're parsing a stored program normally (loading from mysql.proc, ...);

      3. we're re-parsing SET-statement with a user variable after meta-data
        change. It's guaranteed, that:
        - this SET-statement deals with a user/system variable (otherwise, it
          would be a different SP-instruction, and we would parse an expression);
        - this SET-statement has a single user/system variable assignment
          (that's how we generate sp_instr_stmt-instructions for SET-statements).
        So, in this case, even if thd->lex->sphead is set, we should not process
        further.

      4. We are parsing SET STATEMENT FOR ... inside of SP.
  */

  if (!sp ||              // case #1
      sp->is_invoked() || // case #3
      thd->lex->set_statement) // case #4
  {
    return;
  }

  LEX *old_lex= thd->lex;
  sp->reset_lex(thd);
  LEX * const lex= thd->lex;

  /* Set new LEX as if we at start of set rule. */
  lex->sql_command= SQLCOM_SET_OPTION;
  lex->var_list.empty();
  lex->autocommit= false;

  /*
    It's a SET statement within SP. It will be either translated
    into one or more sp_instr_stmt instructions, or it will be
    sp_instr_set / sp_instr_set_trigger_field instructions.
    In any case, position of SP-variable can not be determined
    reliably. So, we set the start pointer of the current statement
    to NULL.
  */
  sp->m_parser_data.set_current_stmt_start_ptr(NULL);
  sp->m_parser_data.set_option_start_ptr(option_ptr);

  /* Inherit from outer lex. */
  lex->option_type= old_lex->option_type;
}


/**
  Create a SP instruction for a SET assignment.

  @see sp_create_assignment_lex

  @param thd           Thread context
  @param expr_end_ptr  Option-value-expression end pointer

  @return false if success, true otherwise.
*/

bool sp_create_assignment_instr(THD *thd, const char *expr_end_ptr)
{
  LEX *lex= thd->lex;
  sp_head *sp= lex->sphead;

  /*
    We can come here in the following cases:

      1. it's a regular SET statement outside stored programs
        (lex->sphead is NULL);

      2. we're parsing a stored program normally (loading from mysql.proc, ...);

      3. we're re-parsing SET-statement with a user variable after meta-data
        change. It's guaranteed, that:
        - this SET-statement deals with a user/system variable (otherwise, it
          would be a different SP-instruction, and we would parse an expression);
        - this SET-statement has a single user/system variable assignment
          (that's how we generate sp_instr_stmt-instructions for SET-statements).
        So, in this case, even if lex->sphead is set, we should not process
        further.

      4. It's a SET STATEMENT ... FOR CREATE PROCEDURE and should be treated as
      case 1 even though lex->sphead != NULL.
  */

  if (!sp ||              // case #1
      sp->is_invoked() || // case #3
      lex->set_statement) // case #4
  {
    return false;
  }

  if (!lex->var_list.is_empty())
  {
    /* Extract expression string. */

    const char *expr_start_ptr= sp->m_parser_data.get_option_start_ptr();

    LEX_STRING expr;
    expr.str= (char *) expr_start_ptr;
    expr.length= expr_end_ptr - expr_start_ptr;

    /* Construct SET-statement query. */

    LEX_STRING set_stmt_query;

    set_stmt_query.length= expr.length + 3;
    set_stmt_query.str= (char *) thd->alloc(set_stmt_query.length + 1);

    if (!set_stmt_query.str)
      return true;

    strmake(strmake(set_stmt_query.str, "SET", 3),
            expr.str, expr.length);

    /*
      We have assignment to user or system variable or option setting, so we
      should construct sp_instr_stmt for it.
    */

    sp_instr_stmt *i=
      new (thd->mem_root)
        sp_instr_stmt(sp->instructions(), lex, set_stmt_query);

    if (!i || sp->add_instr(thd, i))
      return true;
  }

  /* Remember option_type of the currently parsed LEX. */
  enum_var_type inner_option_type= lex->option_type;

  if (sp->restore_lex(thd))
    return true;

  /* Copy option_type to outer lex in case it has changed. */
  thd->lex->option_type= inner_option_type;

  return false;
}