Re: [Bug-tar] bad treatment of symlinks

[Paul Eggert]

On 10/18/11 11:16, Andries E. Brouwer wrote:
> (i) Good! So the option exists, only is undocumented.

The option is documented, but its documentation was incomplete.
I attempted to fix that by installing a patch
<http://git.savannah.gnu.org/cgit/tar.git/commit/?id=1e1fc0336bea2f273b8c6fdb376735ce13887899>.
Further patches would be welcome; the documentation needs a lot of
work, but I lack the time.

> (ii) "tar manual" - my default Ubuntu system does not have it.

That's an Ubuntu issue, not a tar issue.  I expect it will be fixed
whenever Ubuntu gets around to it; perhaps as a user you might file a
bug report with them to accelerate the process.  Your complaints about
tar's documentation's license are no longer correct, as the license
was recently changed.

> tar is used to archive and unarchive filesystem trees.
> In such a situation following symlinks is a very bad idea,
> both when packing and when unpacking.

Well, it depends on the circumstance.  Often people want to
follow the symlinks when extracting: they want to overlay the
archived tree atop an existing filesystem tree, and they want
to follow the symlinks in the existing tree.

Also, in general, there is no efficient and reliable way to avoid
following arbitrary symlinks when extracting.  I am aware of other tar
implementations that try to do it, but they're slower and as far as I
can tell they don't fix all the race conditions.  It might be helpful
for tar to do something similar, if a way can be found that doesn't
hurt performance much, but this does not seem to be an urgent issue.