changing file copy to support extended attributes

changing file copy to support extended attributes

[Eric Chen]

Hi,

I wanted to modify file copy so it supports extended attributes. I am using
extended attributes provided by the XFS filesystem, and right now when I
copy a file with an extended attribute bit set on, the copy of the file does
not preserve the extended attribute. I could use some help in this area
because I am not sure where to start. If anyone has some suggestions or can
offer me some help or resources to go to, please let me know.

Thanks,
Eric
echen@ateonix.com

Re: changing file copy to support extended attributes

[Andreas Dilger]

On Feb 12, 2003  11:35 -0800, Eric Chen wrote:
> I wanted to modify file copy so it supports extended attributes. I am using
> extended attributes provided by the XFS filesystem, and right now when I
> copy a file with an extended attribute bit set on, the copy of the file does
> not preserve the extended attribute. I could use some help in this area
> because I am not sure where to start. If anyone has some suggestions or can
> offer me some help or resources to go to, please let me know.

Probably only user-space changes are needed.  I think there are already
modified tools for this.  See http://acl.bestbits.at.

Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://www-mddsp.enel.ucalgary.ca/People/adilger/

Re: changing file copy to support extended attributes

[Jesse Pollard]

On Wednesday 12 February 2003 01:35 pm, Eric Chen wrote:
> Hi,
>
> I wanted to modify file copy so it supports extended attributes. I am using
> extended attributes provided by the XFS filesystem, and right now when I
> copy a file with an extended attribute bit set on, the copy of the file
> does not preserve the extended attribute. I could use some help in this
> area because I am not sure where to start. If anyone has some suggestions
> or can offer me some help or resources to go to, please let me know.

You have to modify "cp" and "mv" (since a "mv" that crosses mount points
is equivalent to a "cp original destination/copy; rm original".

Now you also need to realize that you might NOT be able to copy all of the 
extended attributes (XFS supports system and user attributes, and only the
user attributes can be copied). This is the usual reason extended attributes
are not copied at all.

Another is what about applications that may copy files too: cat, tar, cpio, 
dd, vi, ed, ... and sh (remember the old "shcat" script:
	while[read v]; do; echo $v; done <original >copy)

And what do you do if the destination is not XFS?

And what about when the user is not the owner of the file, but does have read 
access?

-- 
-------------------------------------------------------------------------
Jesse I Pollard, II
Email: pollard@navo.hpc.mil

Any opinions expressed are solely my own.