Re: `du` check for directory loop avoidance

[Bernhard Voelker]

On 12/18/2013 07:41 PM, Pádraig Brady wrote:
> I need to look into this some more,
> but we should at least reword the warning to something more generic

BTW: the diagnostic in du(1) has been improved in 8.20 by commit

  http://git.sv.gnu.org/cgit/coreutils.git/commit/?id=cf7e1b5b

but chcon, chmod, chown, chgrp, rm, and mv are affected, too:

  $ git grep emit_cycle_warning | cat
  src/chcon.c:          emit_cycle_warning (file_full_name);
  src/chmod.c:          emit_cycle_warning (file_full_name);
  src/chown-core.c:          emit_cycle_warning (file_full_name);
  src/du.c:                emit_cycle_warning (file);
  src/remove.c:      emit_cycle_warning (ent->fts_path);
  src/system.h:#define emit_cycle_warning(file_name)    \

e.g.

  $ mount -t tmpfs tmpfs /mnt

  $ mkdir /mnt/mnt

  $ mount --bind /mnt /mnt/mnt

  $ du /mnt
  du: mount point ‘/mnt/mnt’ already traversed
  0     /mnt

  $ chown -R root  /mnt
  chown: WARNING: Circular directory structure.
  This almost certainly means that you have a corrupted file system.
  NOTIFY YOUR SYSTEM MANAGER.
  The following directory is part of the cycle:
    ‘/mnt/mnt’

Just for the record, non-FTS ls(1) uses a different diagnostic:

  $ ls -R /mnt
  /mnt:
  mnt
  ls: /mnt/mnt: not listing already-listed directory

It seems that there is still room for improvement.

Have a nice day,
Berny