Re: memory leak in getprotobyname()

[Daniel Jacobowitz]

On Tue, Dec 02, 2003 at 09:59:46AM -0500, Roman Fleysher wrote:
> 
> I am not an expert on the subject, but it looks as if getprotobyname()
> allocates a structure and returns a pointer to it. Thus, each time you
> call it, new structure is allocated and new pointer is returned. You can
> check it with
> 
> if(getprotobyname("tcp") != getprotobyname("tcp"))
>   printf("Each call allocates new structure
>           (assuming these were not NULL's)\n");

That's incorrect.  From the manual:

   You can use `getprotobyname' and `getprotobynumber' to search the
protocols database for a specific protocol.  The information is
returned in a statically-allocated structure; you must copy the
information if you need to save it across calls.

> 
> Roman
> 
> > ========================8<============================
> > #include <netdb.h>
> > #include <stdio.h>
> >
> > int main(void) {
> >     int i;
> >     struct protoent *protocol=NULL;
> >
> >     for (i=0; i<200000; i++) {
> >         protocol=getprotobyname("tcp");
> >     }
> >     printf("\n RESULT : %02x \n",protocol->p_proto);
> >
> >     return 0;
> > }
> > ========================8<============================
> 
> 
> 
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> 

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer