Re: [Bug-tar] [PATCH] add a numeric offset option for uid and gid manipulations

[Glauber Costa]

On 03/12/2013 11:03 PM, Paul Eggert wrote:
> On 03/12/13 11:43, Glauber Costa wrote:
>> If you are extracting an archive that contains a distribution image with
>> a particular user, there is no guarantee that such user exists in the
>> host system. Much less that it has an equal user id.
> 
> Sure, but that's the way that 'tar' has always worked.
> What I'm not understanding is what is new here.
> 
> If the tar archive says that the file F is
> owned by a user with name 'root' and user ID 0,
> and if you run 'tar x' in an environment where the
> user named 'root' has ID 10000, then tar normally
> will extract into a file owned by 'root' with
> user ID 10000.  Isn't that's what you want here?
> 

Except that we might be extracting the actual environment, which is
usually what we're doing at tar extract time of the distribution image.
There is not yet anything to do that mapping.

The only option becomes to create a separate user namespace just to
extract the file, which means always having a helper script for
situations like that. At this point, I personally think it is a lot
easier to just augment the tooling with such capability.