Re: [bug #17877] Invalid "No such file or directory" error on filesystem without stable inode numbers

[James Youngman]

On 10/7/06, Miklos Szeredi <address@hidden> wrote:
> > Yes, for systems with O_NOFOLLOW, that is a perfect (efficient, race
> > free) solution.  For systems without O_NOFOLLOW, just moving the
> > lstat() and the open() close to each other
>
> Actually moving the lstat() _after_ the open() totally removes the
> race for inode-less filesystems.  The following should be equivalent
> to open(O_NOFOLLOW):
>
>         fd = open(path);
>         lstat(path, &st1);
>         fstat(fd, &st2);
>         if (st1.st_ino != st2.st_ino)
>                 /* ELOOP */;

For find, the stat result (in the absence of type information in
struct dient) determines if we need to consider descending into a
directory.  I'm very reluctant to try opening every file in the
filesystem just in case it turns out to be a directory we need to
descend into.  But then, the underlying principle of your technique
will doubtless be useful even if it needs to be adapted to work
efficiently for find.

James