Re: [v9.2] LEAKPROOF attribute of FUNCTION (Re: [v9.2] Fix Leaky View Problem)

2012/1/25 Robert Haas <robertmhaas@gmail.com>:
> On Sun, Jan 22, 2012 at 5:12 AM, Kohei KaiGai <kaigai@kaigai.gr.jp> wrote:
>> 2012/1/21 Robert Haas <robertmhaas@gmail.com>:
>>> On Sat, Jan 21, 2012 at 3:59 AM, Kohei KaiGai <kaigai@kaigai.gr.jp> wrote:
>>>> I marked the default leakproof function according to the criteria that
>>>> does not leak contents of the argument.
>>>> Indeed, timestamp_ne_timestamptz() has a code path that rises
>>>> an error of "timestamp out of range" message. Is it a good idea to
>>>> avoid mark "leakproof" on these functions also?
>>>
>>> I think that anything which looks at the data and uses that as a basis
>>> for whether or not to throw an error is non-leakproof.  Even if
>>> doesn't directly leak an arbitrary value, I think that leaking even
>>> some information about what the value is no good.  Otherwise, you
>>> might imagine that we would allow /(int, int), because it only leaks
>>> in the second_arg = 0 case.  And you might imagine we'd allow -(int,
>>> int) because it only leaks in the case where an overflow occurs.  But
>>> of course the combination of the two allows writing something of the
>>> form 1/(a-constant) and getting it pushed down, and now you have the
>>> ability to probe for an arbitrary value.  So I think it's just no good
>>> to allow any leaking at all: otherwise it'll be unclear how safe it
>>> really is, especially when combinations of different functions or
>>> operators are involved.
>>>
>> OK. I checked list of the default leakproof functions.
>>
>> Functions that contains translation between date and timestamp(tz)
>> can raise an error depending on the supplied arguments.
>> Thus, I unmarked leakproof from them.
>>
>> In addition, varstr_cmp() contains translation from UTF-8 to UTF-16 on
>> win32 platform; that may raise an error if string contains a character that
>> is unavailable to translate.
>> Although I'm not sure which case unavailable to translate between them,
>> it seems to me hit on the basis not to leak what kind of information is
>> no good. Thus, related operator functions of bpchar and text got unmarked.
>> (Note that bpchareq, bpcharne, texteq and textne don't use it.)
>
> Can you rebase this?  It seems that the pg_proc.h and
> select_views{,_1}.out hunks no longer apply cleanly.
>
OK, the attached one is the rebased one.

Thanks,
--
KaiGai Kohei <kaigai@kaigai.gr.jp>