On Thu, Sep 27, 2001 at 09:26:12AM +0200, Christof Petig wrote:
> Tom Lane wrote:
>
> > >> Well at least on glibc-2.2 it seems that setlocale retuns a pointer to
> > >> malloced memory, and frees this pointer on subsequent calls to
> > >> setlocale.
> > >> So I would kindly ask you to take a second look at every invokation of
> > >> setlocale.
> >
> > I looked around, and am worried about the behavior of PGLC_current()
> > in src/backend/utils/adt/pg_locale.c. It doesn't change locale but
> > does retrieve several successive setlocale() results. Does that work
> > in glibc?
>
> Well actually I did not check glibc's source code. But I tried to run my
> program with efence and it aborted in execute.c
I see locale/setlocale.c in glibc (I'm very like that PG hasn't same
coding style as glibc developers:-). You are right with strdup()/free()
in the setlocale().
>
> [ locale=setlocale(LC_NUMERIC,NULL);
> setlocale(LC_NUMERIC,"C");
> ...
> setlocale(LC_NUMERIC,locale); // access to already freed memory
> (locale)
> ]
>
> So my best guess is that setlocale
> - uses a malloced memory for return (which copes best with variable length
> strings)
> - frees this on a subsequent calls and allocates a new one.
>
> Yes, I'm worried about PGLC_current(), too.
For example to_char() calls PGLC_localeconv(). In the PGLC_localeconv()
is used:
PGLC_current(&lc);
setlocale(LC_ALL, "");
PGLC_setlocale(&lc); /* <-- access to free memory ? */
I see now it in detail and Christof probably found really pretty bug.
Some users already notice something like:
test=# select to_char(45123.4, 'L99G999D9');
NOTICE: pg_setlocale(): 'LC_MONETARY=pŠ-@č' cannot be honored.
to_char
-------------
Kč 45 123,4
(1 row)
(I use Czech locales)
We don't see this bug often, because PGLC_localeconv() result is cached
and pg_setlocale is called only once.
It must be fixed for 7.2. May be allocate it in PG, because we need
keep data in PG_LocaleCategories independent on glibc's strdup/free.
May be:
PGLC_current(PG_LocaleCategories * lc)
{
lc->lang = getenv("LANG");
PGLC_free_caltegories(lc);
lc->lc_ctype = pstrdup(setlocale(LC_CTYPE, NULL));
... etc.
}
void
PGLC_free_caltegories(PG_LocaleCategories * lc)
{
if (lc->lc_ctype)
pfree(lc->lc_ctype);
...etc.
}
Comments? I right now work on patch for this.
--
Karel Zak <zakkr@zf.jcu.cz>
http://home.zf.jcu.cz/~zakkr/
C, PostgreSQL, PHP, WWW, http://docs.linux.cz, http://mape.jcu.cz
