misc/150972: symbolic link bug
brde at optusnet.com.au
Sun Sep 26 20:25:47 UTC 2010
On Sun, 26 Sep 2010, Kevin K. Han wrote:
> 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.
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