bug#29788: chown: recursive operation with "-H" flag does not work as documented

[Bernhard Voelker]

tag 29788 notabug
stop

On 12/20/2017 07:24 PM, Michael Orlitzky wrote:
> The documentation for the "-H" flag to chown says,
>
>    The  following  options modify how a hierarchy is traversed when the
>    -R option is also specified.  If more than one  is  specified,  only
>    the final one takes effect.
>
>      -H     if a command line argument is a symbolic link to a directory,
>             traverse it
>
> This is not doing what I think it should do. In a terminal, as my "mjo"
> system user, I can run,
>
>    $ mkdir foo
>    $ mkdir bar
>    $ ln -s ../bar foo/baz
>    $ sudo chown --verbose --recursive -H root foo
>
> which outputs...
>
>    changed ownership of 'foo/baz' from mjo to root
>    changed ownership of 'foo' from mjo to root
>
> However, the path "foo/baz" was not passed on the command-line, and
> chown did in fact follow the symlink,
>
>    $ ls -l | grep bar
>    drwxr-xr-x  2 root mjo 4.0K 2017-12-20 13:19 bar
>
> as evidenced by the fact that "bar" was created as mjo:mjo.

I think there is something else going on you didn't consider:

      --dereference      affect the referent of each symbolic link (this is
                         the default), rather than the symbolic link itself

The -H option does not affect 'foo/baz' (or the target it references),
but only the command line arg 'foo'.  So the test case for -H is:

  $ mkdir bar bar/baz
  $ ln -s bar foo

  $ sudo chown --verbose --recursive -H root foo
  changed ownership of 'foo/baz' from berny to root
  changed ownership of 'foo' from berny to root

  $ find . -ls
  4014266      4 drwxr-xr-x   3  berny    users        4096 Dec 20 21:50 .
  4014269      4 drwxr-xr-x   3  root     users        4096 Dec 20 21:50 ./bar
  4014271      4 drwxr-xr-x   2  root     users        4096 Dec 20 21:50 
./bar/baz
  4014272      0 lrwxrwxrwx   1  berny    users           3 Dec 20 21:50 ./foo 
-> bar

Without -H, chown would not dereference 'foo', and change the ownership of
the symlink (on systems which support this):

  $ sudo chown --verbose --recursive root foo
  changed ownership of 'foo' from berny to root

  $ find . -ls
  4014266      4 drwxr-xr-x   3  berny    users        4096 Dec 20 21:51 .
  4014269      4 drwxr-xr-x   3  berny    users        4096 Dec 20 21:51 ./bar
  4014271      4 drwxr-xr-x   2  berny    users        4096 Dec 20 21:51 
./bar/baz
  4014272      0 lrwxrwxrwx   1  root     users           3 Dec 20 21:51 ./foo 
-> bar

Thus, I think this not a bug in chmod or the documentation, but in the
your expectations.  Therefore, I'm marking this as not-a-bug in our bug
tracker.  Of course, you are welcome to continue the discussion, and if
needed we can reopen this issue at a later point.

Have a nice day,
Berny