Commit 1539b039 authored by unknown's avatar unknown
Browse files

Fix for #5730 (Query cache crashes server) 

Recusive part leads to stack overflow


sql/sql_cache.cc:
  Recursion removed from Query_cache::allocate_data_chain
parent 99e3f21c

sql/sql_cache.cc

+37 −38
Original line number Diff line number Diff line
@@ -1843,7 +1843,6 @@ inline ulong Query_cache::get_min_append_result_data_size() 
/*

  Allocate one or more blocks to hold data

*/



my_bool Query_cache::allocate_data_chain(Query_cache_block **result_block,

					 ulong data_len,

					 Query_cache_block *query_block,
@@ -1851,55 +1850,55 @@ my_bool Query_cache::allocate_data_chain(Query_cache_block **result_block, 
{

  ulong all_headers_len = (ALIGN_SIZE(sizeof(Query_cache_block)) +

			   ALIGN_SIZE(sizeof(Query_cache_result)));

  ulong len= data_len + all_headers_len;

  ulong align_len= ALIGN_SIZE(len);

  ulong min_size = (first_block_arg ?

		    get_min_first_result_data_size():

		    get_min_append_result_data_size());

  Query_cache_block *prev_block= NULL;

  Query_cache_block *new_block;

  DBUG_ENTER("Query_cache::allocate_data_chain");

  DBUG_PRINT("qcache", ("data_len %lu, all_headers_len %lu",

			data_len, all_headers_len));



  ulong min_size = (first_block_arg ?

		    get_min_first_result_data_size():

		    get_min_append_result_data_size());

  *result_block = allocate_block(max(min_size, align_len),

  do

  {

    ulong len= data_len + all_headers_len;

    ulong align_len= ALIGN_SIZE(len);



    if (!(new_block= allocate_block(max(min_size, align_len),

				    min_result_data_size == 0,

				    all_headers_len + min_result_data_size,

				 1);

  my_bool success = (*result_block != 0);

  if (success)

				    1)))

    {

    Query_cache_block *new_block= *result_block;

      DBUG_PRINT("warning", ("Can't allocate block for results"));

      DBUG_RETURN(FALSE);

    }



    new_block->n_tables = 0;

    new_block->used = 0;

    new_block->used = min(len, new_block->length);

    new_block->type = Query_cache_block::RES_INCOMPLETE;

    new_block->next = new_block->prev = new_block;

    Query_cache_result *header = new_block->result();

    header->parent(query_block);



    if (new_block->length < len)

    {

    DBUG_PRINT("qcache", ("Block len %lu used %lu",

			  new_block->length, new_block->used));



    if (prev_block)

      double_linked_list_join(prev_block, new_block);

    else

      *result_block= new_block;

    if (new_block->length >= len)

      break;



    /*

      We got less memory then we need (no big memory blocks) =>

      Continue to allocated more blocks until we got everything we need.

    */

      Query_cache_block *next_block;

      if ((success = allocate_data_chain(&next_block,

					 len - new_block->length,

					 query_block, first_block_arg)))

	double_linked_list_join(new_block, next_block);

    }

    if (success)

    {

      new_block->used = min(len, new_block->length);

    data_len= len - new_block->length;

    prev_block= new_block;

  } while(1);



      DBUG_PRINT("qcache", ("Block len %lu used %lu",

			  new_block->length, new_block->used));

    }

    else

      DBUG_PRINT("warning", ("Can't allocate block for continue"));

  }

  else

    DBUG_PRINT("warning", ("Can't allocate block for results"));

  DBUG_RETURN(success);

  DBUG_RETURN(TRUE);

}



/*****************************************************************************