mariadb/sql/thr_malloc.cc

/*
   Copyright (c) 2000, 2010, 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 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 02110-1301  USA */


/* Mallocs for used in threads */

#include <my_global.h>
#include "sql_priv.h"
#include "unireg.h"
#include "thr_malloc.h"
#include "sql_class.h"

extern "C" {
  void sql_alloc_error_handler(void)
  {
    THD *thd= current_thd;
    if (thd)
    {
      if (! thd->is_error())
      {
        /*
          This thread is Out Of Memory.
          An OOM condition is a fatal error.
          It should not be caught by error handlers in stored procedures.
          Also, recording that SQL condition in the condition area could
          cause more memory allocations, which in turn could raise more
          OOM conditions, causing recursion in the error handling code itself.
          As a result, my_error() should not be invoked, and the
          thread diagnostics area is set to an error status directly.
          Note that Diagnostics_area::set_error_status() is safe,
          since it does not call any memory allocation routines.
          The visible result for a client application will be:
          - a query fails with an ER_OUT_OF_RESOURCES error,
          returned in the error packet.
          - SHOW ERROR/SHOW WARNINGS may be empty.
        */
        thd->get_stmt_da()->set_error_status(ER_OUT_OF_RESOURCES);
      }
    }

    /* Skip writing to the error log to avoid mtr complaints */
    DBUG_EXECUTE_IF("simulate_out_of_memory", return;);

    sql_print_error("%s", ER_THD_OR_DEFAULT(thd, ER_OUT_OF_RESOURCES));
  }
}

void init_sql_alloc(MEM_ROOT *mem_root, uint block_size, uint pre_alloc,
                    myf my_flags)
{
  init_alloc_root(mem_root, block_size, pre_alloc, my_flags);
  mem_root->error_handler=sql_alloc_error_handler;
}


char *sql_strmake_with_convert(THD *thd, const char *str, size_t arg_length,
			       CHARSET_INFO *from_cs,
			       size_t max_res_length,
			       CHARSET_INFO *to_cs, size_t *result_length)
{
  char *pos;
  size_t new_length= to_cs->mbmaxlen*arg_length;
  max_res_length--;				// Reserve place for end null

  set_if_smaller(new_length, max_res_length);
  if (!(pos= (char*) thd->alloc(new_length + 1)))
    return pos;					// Error

  if ((from_cs == &my_charset_bin) || (to_cs == &my_charset_bin))
  {
    // Safety if to_cs->mbmaxlen > 0
    new_length= MY_MIN(arg_length, max_res_length);
    memcpy(pos, str, new_length);
  }
  else
  {
    uint dummy_errors;
    new_length= copy_and_convert((char*) pos, new_length, to_cs, str,
				 arg_length, from_cs, &dummy_errors);
  }
  pos[new_length]= 0;
  *result_length= new_length;
  return pos;
}