GNU bug report logs - #17035
[PATCH] chmod -c -R produces errors with special permissions

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From: Bernhard Voelker <mail <at> bernhard-voelker.de>
To: Pádraig Brady <P <at> draigBrady.com>
Cc: dylan <at> dylex.net, 17035 <at> debbugs.gnu.org
Subject: bug#17035: [PATCH] chmod -c -R produces errors with special permissions
Date: Wed, 19 Mar 2014 08:57:09 +0100

On 03/19/2014 12:41 AM, Pádraig Brady wrote:
> On 03/18/2014 10:18 PM, Bernhard Voelker wrote:
>> One question: I did not dig into this deeper yet, but what exactly
>> is the connection between "directory with special permissions"
>> vs. "stat()ing the wrong file"?
>> I'm asking because incidentally yesterday I saw the same warning
>> from "chmod -R -c" when playing with recursive bind-mounts, i.e.,
>> there were no files or directories with special bits set.
>
> Interesting. Looking at the code seems that message
> is restricted to the above condition where those bits are set.
> Can you reproduce?

Yes, fortunately - and now I see that my case implicitly was
using +t mode because of the TMPFS file system type:

  $ mount -t tmpfs /mnt /mnt

  $ mkdir -p /mnt/dir/mnt

  $ mount --bind /mnt /mnt/dir/mnt

  $ cd /mnt

  $ ln -s dir/mnt/dir d

  $ ls -ldogi . d dir dir/mnt
  186326 drwxrwxrwt 3 80 Mar 19 08:31 .
  188029 lrwxrwxrwx 1 11 Mar 19 08:31 d -> dir/mnt/dir
  188511 drwxr-xrwx 3 60 Mar 19 08:31 dir
  186326 drwxrwxrwt 3 80 Mar 19 08:31 dir/mnt

  $ chmod -Rc o+w dir
  mode of ‘dir’ changed from 0755 (rwxr-xr-x) to 0757 (rwxr-xrwx)
  chmod: getting new attributes of ‘mnt’: No such file or directory
  mode of ‘dir/mnt/dir/mnt’ changed from 0755 (rwxr-xr-x) to 0757 (rwxr-xrwx)

As a final side note to this case, I want to mention that the issue
also happens with the -v option, of course:

  $ mkdir -p a/b
  $ chmod +t a/b
  $ chmod -Rv o+w a
  mode of ‘a’ changed from 0755 (rwxr-xr-x) to 0757 (rwxr-xrwx)
  chmod: getting new attributes of ‘b’: No such file or directory
  mode of ‘a/b’ retained as 1757 (rwxr-xrwt)

Thanks & have a nice day,
Berny

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