Date: Sun, 26 Sep 2010 20:30:09 GMT From: Bruce Evans <brde@optusnet.com.au> To: freebsd-bugs@FreeBSD.org Subject: Re: misc/150972: symbolic link bug Message-ID: <201009262030.o8QKU9hM065296@freefall.freebsd.org>
next in thread | raw e-mail | index | archive | help
The following reply was made to PR misc/150972; it has been noted by GNATS.
From: Bruce Evans <brde@optusnet.com.au>
To: "Kevin K. Han" <ikevin.c11@revvo.org>
Cc: freebsd-gnats-submit@FreeBSD.org, freebsd-bugs@FreeBSD.org
Subject: Re: misc/150972: symbolic link bug
Date: Mon, 27 Sep 2010 06:25:42 +1000 (EST)
On Sun, 26 Sep 2010, Kevin K. Han wrote:
>> Description:
> Create a directory on the root folder, for example ("/whatever").
> Switch to user's home directory ("cd /usr/home/username") ... from now onwards, work in this directory:
> Create a symbolic link from inside a user's home ("ln -s /whatever .")
> Execute this: ("chown -R username:username whatever")
Apparently you are still running as root after creating /whatever. This
chown -R has no effect even as root. (A plain chown would change /whatever
and chown -h would change the symlink.)
> Try to delete it using ("rm whatever")... it will say it is a directory. It is still not deleted!
I don't see this. It would be a bad bug. rm is required to not follow
symlinks. A broken version of rm might stat() the symlink and decide
that it is a directory, and then rewrite its name to "whatever/" for
maximal brokenness (other utilities do need to append a slash sometimes,
and this is not easy to get right); then unlink("whatever/") would say
it is a directory.
> Then, try to delete using ("rm -r -f whatever/"), no errormessage, BUT It is still there!
This is how symlinks work. "whatever/" is whatever the symlink points to.
It is "/whatever" here. So this commands removes "/whatever" and leaves
the symlink untouched.
> Then, again, try the same thing ("rm whatever")... It is GONE, INCLUDING the original at "/whatever" !!!
Consistent with a broken rm stat()ing the symlink. The previous command
removed "/whatever", so "whatever" is a dangling symlink and stat()ing it
wouldn't see it as a directory.
Bruce
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201009262030.o8QKU9hM065296>