Date: Sun, 21 Sep 2008 21:50:09 +0200 From: Mel <fbsd.questions@rachie.is-a-geek.net> To: freebsd-questions@freebsd.org, trashy_bumper@yahoo.com Subject: Re: Segmentation fault when free Message-ID: <200809212150.09315.fbsd.questions@rachie.is-a-geek.net> In-Reply-To: <266527.92897.qm@web110502.mail.gq1.yahoo.com> References: <266527.92897.qm@web110502.mail.gq1.yahoo.com>
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On Sunday 21 September 2008 14:57:06 Nash Nipples wrote:
> > > can someone please explain to me what happens to the
> >
> > allocated memory
> >
> > > called within a function assigned to its local pointer
> >
> > after this function
> >
> > > ends
> >
> > Ok - let's see if I get this right:
> > - the allocated memory
> > - called within a function
> > - assigned to a local pointer
> >
> > Any malloc'ed memory is application global accessible.
> > Assigning a pointer to
> > a variable doesn't allocate memory (the compiler and
> > runtime libraries
> > already setup storage for the variable, at declaration
> > time). So, I have no
> > idea what you mean with the "called within a
> > function" part.
> >
> > --
> > Mel
>
> thanks for making it even more clear to me.
> actually what i meant was this:
>
> void function(void){
> char *p;
> p = malloc(1);
> }
> int main(void){
> while (1){
> function();
> /* in the end of this function function()
> * the memory is still allocated
> * even when the only pointer who knows its address
> * does not longer exist
> * which is why we have to free() the memory
> * during the application runtime
> * to avoid it from growing to ridiculous size
> */
> }
> }
Right, this is one of the annoyances of C-programming "Who still knows where
my pointer is". You can use a general rule though:
If I don't return this pointer, and I don't assign this pointer to a
parameter, and I don't assign this pointer to a global variable, I should
free this pointer myself.
(Yes yes, malloc'd static storage - new can of worms).
--
Mel
Problem with today's modular software: they start with the modules
and never get to the software part.
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