Need help to understand small part of sourcecode

[Claudia Moroder]

Hello Simo,

I see you changed to cvs the way status is passed instead of NULL.

For this case this is the solution, but this solutions leaves the door open
for similar errors. What about to test in all functions if passed pointers
are NULL ?  This checks should be conditionally compiled in this way samba
would not be slowed down in the standard case. I remember in windows
programmin there was a statement called ASSERT()
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dshow/htm/a
ssert.asp .
What about to use a similar solution ?


Bye
Andreas

-----Ursprüngliche Nachricht-----
Von: "Simo Sorce" <idra at samba.org>
An: "andreas moroder" <claudiamoroder at st-ulrich.suedtirol.net>
Gesendet: Samstag, 29. Dezember 2001 10:43
Betreff: Re: Need help to understand small part of sourcecode


> On Fri, Dec 28, 2001 at 11:00:08PM +0100, andreas moroder wrote:
> > Hello,
> >
> > it would be nice if anyone could explain me the following sections of
source
> > code
> >
> > In smbd/reply.c  in the function    reply_printqueue ( line 2550 .. )
> >
> >  print_queue_status(SNUM(conn), &queue,NULL) is called with the 3th
parameter
> > NULL.
>
> I think this is a bug.
>
> >
> > in printing/printing.c there is the function print_queue_status
> >
> > .....
> >         ZERO_STRUCTP(status);
> >         slprintf(keystr, sizeof(keystr)-1, "STATUS/%s",
lp_servicename(snum));
> >         key.dptr = keystr;
> >         key.dsize = strlen(keystr);
> >         data = tdb_fetch(tdb, key);
> >         if (data.dptr) {
> >                 if (data.dsize == sizeof(*status)) {
> >                         memcpy(status, data.dptr, sizeof(*status));
<- ??
> >
> >                 }
> >                 SAFE_FREE(data.dptr);
> >         }
> >
> > the line <-?? is not clear to me
> >
> > if status is passed as NULL, the first parameter of memcopy is NULL. How
can
> > data.ptr be copied to nowhere ?
>
> it can't, my bet is that either memcpy see that src is null and return or
we get a segfault here.
>
> >
> > Do I miss anything ?
> >
> > (  I begin to have doubts, that memcpy(status, data.dptr,
sizeof(*status))
> > copies the pointer data.dptr to the pointer status ( not the data ), but
in
> > this case the SAFE_FREE would free the data status points )
>
> no, status is the pointer for a print_status_struct structure, this
instruction mean we want to copy the content of data.dptr in the structure!
>
>
> weel spotted, thanks.
> --
> Simo Sorce       idra at samba.org
> -------------------------------
> Samba Team http://www.samba.org