On Sun, 20 Sep 2009, Ryan Joseph wrote:
> I just read in the man pages that pcre_free is a global variable and
> points to free by default. In Pascal I'm loading it as an external
> function, which the linker accepts but maybe it's not pointing to an
> actual function and thus crashing? I'll have to ask some people who
> are familiar with my Pascal compiler FPC but can you offer any advice
> as to how it should be used? Thank you.
I'm afraid I know nothing about Pascal. In C, having declared pcre_free
correctly, you can just use it just like a normal function (see, for
example, the pcredemo.c example program).
> Btw, I also read that the pointer to be freed is a single block of
> memory so I was able to use another function to call malloc's free
> which seems to work just fine. Maybe it's not necessary I resolve this
> the correct way?
That is OK. The main reason for having pcre_malloc and pcre_free is so
that any calls from *inside* pcre can be trapped if the calling programs
want to.
While checking up on this, I found the following fragment in pcre.h:
-------------------------------------------------------------------------------
/* Indirection for store get and free functions. These can be set to
alternative malloc/free functions if required. Special ones are used in the
non-recursive case for "frames". There is also an optional callout function
that is triggered by the (?) regex item. For Virtual Pascal, these definitions
have to take another form. */
#ifndef VPCOMPAT
PCRE_EXP_DECL void *(*pcre_malloc)(size_t);
PCRE_EXP_DECL void (*pcre_free)(void *);
PCRE_EXP_DECL void *(*pcre_stack_malloc)(size_t);
PCRE_EXP_DECL void (*pcre_stack_free)(void *);
PCRE_EXP_DECL int (*pcre_callout)(pcre_callout_block *);
#else /* VPCOMPAT */
PCRE_EXP_DECL void *pcre_malloc(size_t);
PCRE_EXP_DECL void pcre_free(void *);
PCRE_EXP_DECL void *pcre_stack_malloc(size_t);
PCRE_EXP_DECL void pcre_stack_free(void *);
PCRE_EXP_DECL int pcre_callout(pcre_callout_block *);
#endif /* VPCOMPAT */
-------------------------------------------------------------------------------
I don't know if you are using "Virtual Pascal", but this is a hint that
there is some issue with pcre_free().
I also remembered that PCRE contains this function:
-------------------------------------------------------------------------------
/*************************************************
* Free store obtained by get_substring_list *
*************************************************/
/* This function exists for the benefit of people calling PCRE from non-C
programs that can call its functions, but not free() or (pcre_free)() directly.
Argument: the result of a previous pcre_get_substring_list()
Returns: nothing
*/
PCRE_EXP_DEFN void PCRE_CALL_CONVENTION
pcre_free_substring_list(const char **pointer)
{
(pcre_free)((void *)pointer);
}
-------------------------------------------------------------------------------
Note the comment at the start. Although it is aimed at freeing substring
lists, you'll see that it just calls pcre_free, and so you could use it
to free the compiled regex as well.
Philip
--
Philip Hazel
