Fwd: Re: need help with an rsync patch

[Sherin A]

On Wednesday 14 August 2013 08:29 PM, Justin Pryzby wrote:
> On Wed, Aug 14, 2013 at 04:09:46PM +0530, Sherin A wrote:
>> On Tuesday 13 August 2013 10:24 PM, Justin T Pryzby wrote:
>>>> PS : if any one interested in making a patch with an additional
>>>> option for rsync for  excluding hardlinks with   -links +1 links ,
>>>> please help me , it is easy to  check the file  with an lstat / stat
>>>> system call. Or  is it possible to get a developer documentation for
>>>> rsync with the detailed info ?
>>> You could do that with --exclude, but first, think about the
>>> implications of that.  Your users could make hardlinks to system
>>> files and those owned by other users files (which they can stat) and
>>> that would cause rsync to avoid backing up those files (by either
>>> name, since link count is shared between all links, of course).
>>>
>>> Justin
>> Any further  information related with this  ?
> On what?  How to implement with --exclude?  Or how users could cause
> files to be not backed up, making such an implementation a terrible
> idea?
>
> Justin (off list)
It won't  work with --exclude ,
because

1) we are   identifying all hardlinks with find command and  will be 
placed in a test file  for  a  user
2) Then we do the rsync with --exclude-from=somefile.txt

  But how we solve this timed  raced conditions as follows which happen 
in between the above to steps ,

hax at hax.com [~/hax]# for i in {1..5000}; do ln -f /etc/shadow $i; done

Still the only solution to embedded the option to avoid hardlink if   
need .

-- 
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Regards
Sherin A
http://www.sherin.co.in/