Re: Changes to the filesystem while find is running - comments?

[Tim Nelson]

On Fri, 26 Nov 2004, Martin Buchholz wrote:

> James Youngman wrote:
> > On Fri, Nov 26, 2004 at 03:23:48PM +1100, Tim Nelson wrote:
> >
> >
> > > > What we need to do - and what we do do - is this -
> > > >
> > > > $tmp = <base name of subdirectory>;
> > >
> > >         According to the description by Steve Revilak which was sent
> > > through, if you at this point do:
> > >
> > > $tmp = $tmp + '.';
> > >
> > >         ...then that will fix the problem.  So instead of statting eg.
> > > "/usr/local/bin", you'll be statting "/usr/local/bin/." (note the dot in
> > > the second one).
> >
> >
> > It's an interesting idea.  However, the code we have now in
> > findutils-4.2.8 works, and I'm reluctant to change this again unless
> > we find there's a problem.

	It doesn't bother me either way; I don't use Sun.  I was just 
trying to come up with a solution to the problem; I was under the 
impression that the problem existed on Solaris machines.  :)

> Also, I see some problems with the proposed solution.
> We need to lstat the name without "/." to find out if
> it's a symlink in any case, and stat-ing "foo/." is likely
> to be a little slower than stat-ing "foo", for no good
> reason.  Only users of automounters should pay an automounter tax.

        Ok, so try this sequence:

[Right at the start of the program]------------
if($os = 'Solaris') { $badautomount = 'true'; }
-----------------------------------------------

[In the bit around the sanity check]-----------

$tmp = <base name of subdirectory>;
$old = lstat $tmp;   /* line A */
# Softlink checking here
if($badautomount) {
        $tmp = $tmp + '.';
        $old = lstat $tmp;
}
chdir $dir;          /* line B */
$new = lstat ".";    /* line C */
wd_sanity_check($old, $new);
-----------------------------------------------

        Sure, even non-automounters "pay a tax" now, but it's only:
1.      A once-off OS check
2.      A true/false integer comparison, which should have minimal impact

	Incidentally, I took Bugtraq off the CC list, since they don't 
seem to be posting these anyway.

        :)

--
Tim Nelson
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