Re: Bug#369822: ls -i stats unnecessarily

[James Youngman]

On 6/1/06, Jim Meyering <address@hidden> wrote:

> > The latter is harder because for some files (mount points in a chroot
> > with a buggy glibc) d_ino is nonzero and wrong.  In those cases, you have
> > to use lstat to get the true value.  The invalid d_ino problem came up
> > recently with the report of pwd failing on systems with a losing (and
> > slightly old) glibc.
> >
> > If someone else does all the work to make ensure the optimization
> > is safe, I'd accept a patch.
>
> After writing that, I remembered that this optimization
> has already been done on the trunk.  However, there's no check
> for the glibc problem:
[...]
> The problem is rare enough that I won't be losing any
> sleep over it.  But it would be good to fix it, or at least
> add a test case comparing st_ino vs. d_ino for every readable
> directory from "." up to "/".  Then (from test failure reports)
> we can hope to get an idea of how often the problem arises.

You could stat "/" at startup, and if its inode number is 2 (hint that
we're probably not chrooted), trust d_ino, and don't trust it if d_ino
is not 2 (we're probably chrooted).   The check is only probabilistic,
but it might help.  It shouldn't be fooled by fsirand.

James.