On 03/12/2013 08:12 PM, Paul Eggert wrote: > On 03/12/13 02:03, Glauber Costa wrote: >> With that, it is extremely useful when unpacking tar archives, to be >> able to add that offset to the end result. Specifying a user won't help, >> since the tar archive can have many > > Sorry, I'm not following this part. Why can't you extract the > tar image in a context where the mapping is already in place? > If user "foo" is host user ID 4000, for example, and you're running > in an environment where uid 0 maps to 10000, then presumably > user "foo" is namespace user 14000, which is what you want, no? > You can - if it is a single user that owns all the files in the archive. However, user namespaces provides a 1:1 mapping of a whole range. In the particular context I am interested, we distribute full distribution images. Most files are owned by root, and we would have a 0 -> x mapping. But a lot of others are owned by all the other users in the system (sshd, ntp, apache, etc). So you would have to map 0 -> x, 1 -> x + 1, 2 -> x + 2, etc, for all the available range.
The option I am proposing sums an offset, therefore it will map correctly the whole range.
