Re: bin/55815: tar opens device files

[Joerg Sonnenberger <joerg%bec.de@localhost>]

On Wed, Nov 25, 2020 at 05:55:01AM +0000, Martin Husemann wrote:
> The following reply was made to PR bin/55815; it has been noted by GNATS.
> 
> From: Martin Husemann <martin%duskware.de@localhost>
> To: gnats-bugs%netbsd.org@localhost
> Cc: 
> Subject: Re: bin/55815: tar opens device files
> Date: Wed, 25 Nov 2020 06:54:12 +0100
> 
>  On Tue, Nov 24, 2020 at 08:15:02PM +0000, Joerg Sonnenberger wrote:
>  >  As discussed on IRC, this is a side effect of enabling ACL and extattr
>  >  support OOB. It is avoided when using --no-acls --no-extattr.
>  
>  Those should be the default then, or maybe check (is there a mount flag
>  or something in statvfs?) whether any ACLs or ext attrs could be there at
>  all.

That would be the ostrich approach of ignoring that open with side
effects is fundamentally a bad idea. It also doesn't match what other
tar implementations do and violates POLA just as well.

>  
>  What happens if the device can not be opened at all, will it be left out of
>  the tar?

No ACLs or extattrs will be saved in that case.

Joerg