[tarantool-patches] Re: [PATCH v1 1/1] sql: fix tarantoolSqlite3TupleColumnFast

[Vladislav Shpilevoy <v.shpilevoy@tarantool.org>]

On 06/12/2018 09:59, Kirill Shcherbatov wrote:
> Hi! Thank you for research, I've included your conclusions to
> the commit message.
> 
> 
> The tarantoolSqlite3TupleColumnFast routine used to lookup
> offset_slot in unallocated memory in some cases.
> The assert with exact_field_count same as motivation to change
> old correct assert with field_count in 7a8de28 is not correct.
> assert(format->exact_field_count == 0 ||
>         fieldno < format->exact_field_count);
> The tarantoolSqlite3TupleColumnFast routine requires offset_slot
> that has been allocated during tuple_format_create call. This
> value is stored in indexed field with index that limited with
> index_field_count that is <= field_count. Look at
> tuple_format_alloc for more details.
> 
> The format in cursor triggering valid assertion has such
> structure because first 4 tuples in _space: 257, 272, 276 and
> 280 have an old format of _space with only one field
> (format->field_count == 1).
> It happens because these 4 tuples are recovered not after tuple
> with id 280 which stores actual format of _space. After tuple
> 280 is recovered, an actual format is set in struct space of
> _space and all next tuples have full featured formats.
> 
> So for these 4 tuples tarantoolSqlite3TupleColumnFast can fail
> even if a field exists, is indexed and has a name. Those
> features are just described in a newer format.
> (thank Gerold103 for problem explanation)
> 
> Closes #3772
> 

LGTM. Nikita, please, review. Especially English part.