Re: unknownin/out patch (was [HACKERS] PQescapeBytea is

Tatsuo Ishii wrote:
>>> Tatsuo Ishii wrote:
>>>
>>>>
>>>> Try a multibyte encoding database. For example,
>>>>
>>>> $ createdb -E EUC_JP test $ psql -c 'SELECT
>>>> SUBSTRING('1234567890' FROM 3)' test substring ----------- 3456
>>>>

>>>> (1 row)
>>>>
>>>> Apparently this is wrong. -- Tatsuo Ishii
>>>
>>> This problem exists in CVS tip *without* the unknownin/out
>>> patch:
>>
>> Sure. That has been broken for a while.
>
>
> I guess this actually happened in 1.79 of varlena.c:
>
Yes, I was just looking at that also. It doesn't consider the case of n
= -1 for MB. See the lines:

#ifdef MULTIBYTE
eml = pg_database_encoding_max_length ();

if (eml > 1)
{
sm = 0;
sn = (m + n) * eml + 3;
}
#endif

When n = -1 this does the wrong thing. And also a few lines later:

#ifdef MULTIBYTE
len = pg_mbstrlen_with_len (VARDATA (string), sn - 3);

I think both places need to test for n = -1. Do you agree?

Joe