namei() returns EISDIR for "/" (Re: svn commit: r203990 - head/lib/libc/sys)

[Garrett Cooper]

On Sun, Feb 28, 2010 at 5:11 PM, Alexander Best <alexbestms at wwu.de> wrote:
> i have a small test app to check {rm|mk}dir()'s errnos with certain args like
> /, ., /proc and non-empty dirs. i'll submit it to this thread as soon as i
> also add testcases for syscalls like rename(), unlink(), etc.
>
> most of the errno codes returned after applying your patch look correct. i
> wonder however why rmdir("/proc") returns EACCESS as unprivileged user.
> wouldn't it make more sense to also return EBUSY? why complain about
> permission related matters when even root won't be able to perform the
> operation.

Hmm.. good question. POSIX doesn't fully expound on this case
(http://www.opengroup.org/onlinepubs/009695399/functions/rmdir.html),
and either seem possible...

> also: since namei() takes care of handling the "/" and "." cases couldn't
> those checks in kern_rmdirat() and kern_unlinkat() be removed?
>
> it might also be interesting to look at the changes netbsd, openbsd and
> dragonflybsd have made to vfs_lookup.c. just had a quick look at revision
> 1.121 from netbsd and they have split lookup() into loads of smaller functions
> (see revision 1.117 and 1.118). seems they have been doing a lot of work here
> (using heavy XXX-commenting however).
>
> openbsd hasn't made to many changes to vfs_lookup.c.
>
> matthew dillon seems to have done an incredible job on dragonfly in connection
> with vfs_lookup.c. basically they completely got rid of namei() and are now
> using nlookup() in commit ad57d0edbfceb0cebfb1dce61490df78fcc4a97. the commit
> message is quite long and claims due to this change all syscalls which used to
> call namei() have become a lot less complex after switching to nlookup().
>
> right now vfs_lookup.c in dragonfly contains only some legacy code used for
> compatibility.
>
> again: an incredible job!
>
> +1 for adapting those changes. ;)
>
> cheers.
> alex
>
> btw.: there're a few NAMEI_DIAGNOSTIC ifdefs in vfs_lookup.c to increase
> verbosity.

Thanks,
-Garrett