[maintainer] coreutils-9.0-1: "ln -fs" bug

[Brian Inglis]

On 2025-02-08 22:40, Marco Atzeri via Cygwin wrote:
> Noticed today, not sure it is new nor that is Cygwin specific.
> 
> It can create unrequested circular links, to replicate:
> 
> $ cd /tmp
> $ mkdir dirA
> $ mkdir dirB
> $ cd dirA
> $ ln -fs /tmp/dirB dirB
> $ ls -l
> total 0
> lrwxrwxrwx 1 marco marco 9 Feb  9 06:33 dirB -> /tmp/dirB
> $ cd dirB
> $ ls -l
> total 0
> lrwxrwxrwx 1 marco marco 7 Feb  9 06:25 dirB -> ../dirB
> 
> I built nothing in dirB, but now there is inside a circular link to itself.
> 
> It only happens with "ln -fs" not with "ln -s"

You are forcing the creation and are allowed to do shoot yourself; also a number 
of bugs were introduced with coreutils 9 changing to use f...at() directory 
relative functions, which messed up our patches and forced a reversion.

I have created many of these, so when creating symlinks with ln -s, I now try 
not to use -f, and almost always try to use either -t --target-directory or -T 
--no-target-directory to specify whether a symlink should added into the 
directory, or a link to a file or directory should be created, or replaced with -f.

I am not seeing anything about this in coreutils issues or change logs;
if you can, would you mind checking with coreutils test 9.5;
I am working on 9.6 and will recheck there when usable.

-- 
Take care. Thanks, Brian Inglis              Calgary, Alberta, Canada

La perfection est atteinte                   Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter  not when there is no more to add
mais lorsqu'il n'y a plus rien à retrancher  but when there is no more to cut
                                 -- Antoine de Saint-Exupéry