Backup tool?

[Nuno Sousa]

Hi, sorry to barge in on the conversation like this, but is there a
backup tool that only backs up preferences? Usually I like to backup
my own stuff (and I take the chance to organize my hard-drive), so
that isn't a problem... but I'd like to have some software saving my
firefox, gnome, amule, xchat, etc, prefences on a weekly basis or
something, so that if I need to reinstall (and I don't mind
reinstalling, which is why I don't just backup the entire partition
onto another drive), I could just install the needed applications and
restore my preferences.
Is there such a tool?


On Tue, 19 Oct 2004 16:53:05 +0100, Colin Watson <cjwatson at canonical.com> wrote:
> On Tue, Oct 19, 2004 at 10:40:22PM +0800, John wrote:
> > Colin Watson wrote:
> > >On Tue, Oct 19, 2004 at 09:13:08PM +0800, John wrote:
> > >>I'm not going to spend much time on this. here are som common C
> > >>functions I believe inherently unsafe because they rely on strings not
> > >>being too long, and which are used in mondo:
> > >>strcat()
> > >>strstr()
> > >>sprintf()
> > >>strcpy()
> > >>strchr()
> > >
> > >Not to argue with the rest of your mail, but in what way are strstr()
> > >and strchr() inherently unsafe? They aren't. If what you thought was a
> > >string was already not null-terminated, you've already lost before
> > >calling strstr() or strchr().
> >
> > Maybe you're right, as I stressed I'm not expert in C programming. I'm
> > not sure that reading off the end of a string is inherently hazardous,
> > but a premature termination without a user-comprehensible message isn't
> > helpful.
> >
> > Is carelessly relying on the returned pointer safe?
> 
> Yes. You should check for NULL, but apart from that C's guarantees are
> sufficient.
> 
> > If I search what I think is a pointer to a string "john.is.wacko" but
> > that actually points to some code (do code and data share the same
> > address space?) and write to the target, what then?
> 
> Then you made a very bad mistake somewhere else, and *any* access
> through that pointer is unsafe, not just strstr() and strchr(), and not
> just code that iterates over the memory pointed to by that pointer.
> 
> In your specific example, most architectures will give you a
> segmentation fault.
> 
> > What if the area the pointer points to has been freed? Freed and
> > allocated to something else?
> 
> See above. Also, use valgrind to catch these problems: it's a
> fantastically wonderful tool for any serious C development.
> 
> > Validating the length might help limit the damage.
> 
> In the cases you describe in this mail, it seems more likely to me that
> it would paper over problems in such a way as to make them harder to
> spot before they cause real problems; other detection measures such as
> valgrind will be more effective. In many other cases, validating the
> length is indeed the right thing to do.
> 
> That said, many good C programmers do use the assert() macro to document
> assumptions in their code.
> 
> 
> 
> Cheers,
> 
> --
> Colin Watson                                    [cjwatson at canonical.com]
> 
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> 


-- 
Nuno Sousa