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Date: Sat, 9 Sep 1995 15:09:01 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199509090509.PAA13536@godzilla.zeta.org.au>
To: davidg@freefall.freebsd.org, hackers@freefall.freebsd.org,
        julian@freefall.freebsd.org
Subject: Re: bug in 4.4lite (fixed in lite2)
Sender: hackers-owner@FreeBSD.org
Precedence: bulk

>[4.4lite]...
>is back to front.. all the t (to) variables should be f (from) and visa versa.

>touch a
>ln a b
>mv a b

>results in a  remaining and b being deleted

I can't test this here, because I implemented the POSIX spec, which clearly
although probably incorrectly specifies that the rename() shall do nothing:

"
5.5.3.2 ...
If the old argument and the new argument both refer to links to the same
                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^
existing file, the rename() function shall return successfully and perform
^^^^^^^^^^^^^
no other action.
"

4.4lite only does nothing if the old argument and the new argument refer
to the same directory entry.  A `file' is quite different from a `directory
entry' in the context of functions such as unlink() and rename() that
operate on directory entries.

>[4.4lite2]
>get's it right..
>I just noticed this when adding rename to devfs..
>but 4.4l2 noticed before me :)

msdosfs is probably broken too (apart from msdosfs_rename() being broken
in other ways).

Bruce

*** vfs_syscalls.c~	Tue Aug 29 03:53:24 1995
--- vfs_syscalls.c	Wed Sep  6 20:41:50 1995
***************
*** 1844,1847 ****
--- 1845,1849 ----
  	if (fvp == tdvp)
  		error = EINVAL;
+ #if 0
  	/*
  	 * If source is the same as the destination (that is the
***************
*** 1854,1857 ****
--- 1856,1868 ----
  	      fromnd.ni_cnd.cn_namelen))
  		error = -1;
+ #else
+ 	/*
+ 	 * If the source is the same as the destination (that is, if they
+ 	 * are links to the same vnode), then there is nothing to do.
+ 	 * POSIX standard.
+ 	 */
+ 	if (fvp == tvp)
+ 		error = -1;
+ #endif
  out:
  	if (!error) {