From: Dmitry Lenev
Date: May 23 2011 1:38pm
Subject: Re: bzr commit into mysql-5.5 branch (luis.soares:3386)
 Bug#12558519
List-Archive: http://lists.mysql.com/commits/137861
Message-Id: <20110523133821.GA1664@bandersnatch>
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Hello Luis!

* Luis Soares <luis.soares@stripped> [11/05/23 13:21]:
> #At file:///home/lsoares/Workspace/bzr/work/bugfixing/12558519/mysql-5.5/ based on revid:marc.alff@stripped
> 
>  3386 Luis Soares	2011-05-23
>       BUG#12558519: RPL_TYPECONV PRODUCES VALGRIND STACK
>       
>       In RBR and in case of converting blob fields, the space allocated
>       while unpacking into the conversion field was not freed after
>       copying from it into the real field.
>       
>       We fix this by freeing the conversion field when the conversion
>       table is not needed anymore (on close_tables_to_lock).

...

> === modified file 'sql/table.cc'
> --- a/sql/table.cc	2011-03-25 14:03:44 +0000
> +++ b/sql/table.cc	2011-05-23 09:17:17 +0000
> @@ -2188,7 +2188,8 @@ void free_blobs(register TABLE *table)
>    for (ptr= table->s->blob_field, end=ptr + table->s->blob_fields ;
>         ptr != end ;
>         ptr++)
> -    ((Field_blob*) table->field[*ptr])->free();
> +    if (table->field[*ptr])
> +      ((Field_blob*) table->field[*ptr])->free();
>  }

I think it is better to add small comment here that will explain
why do we have to check if table->field[*ptr] is not NULL.
Something like:

/*
  Reduced TABLE objects which are used by row-based replication for
  type conversion might have some fields missing. Skip freeing BLOB
  buffers for such missing fields.
*/

Otherwise I am OK with your patch and think that it can be pushed
after considering the above suggestion and getting approval from an
expert from Replication team.

-- 
Dmitry Lenev, Software Developer
Oracle Development SPB/MySQL, www.mysql.com

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