Re: [Bug-tar] tar writes invalid mtime for times before the epoch

[Joerg Schilling]

Paul Eggert <address@hidden> wrote:

> Rodrigo Queiro wrote:
>
> > I discovered this because Python's tarfile module fails to open such files
> > with "invalid header", since it expects this field to contain an ASCII
> > number, as described in the docs:
>
> That's a shortcoming in tar's documentation. Tar uses the GNU format by 
> default, 
> which has a base-256 extension that supports negative timestamps. If you want 
> GNU tar to refuse to use this GNU extension, please use '-H ustar'.

Well, base-256 is not even special to GNU tar. It has been introduced by star 
before and was later adopted by GNU tar.

The background is that base-256 allows up to 95 bits + sign bit and this is 
sufficient for all possible storage as long as you cannot manage to store part 
of the data in a parallel universe.

Jörg

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