tar option suggestion

[Jim Hefferon]

Hello,

I am the maintainers of the TeX ftp and web archive at tug.ctan.org,
of the three sites in the Comprehensive TeX Archive Network.  We have
a recurring issue with tar.  May I ask that the tar maintainer consider
adding an option flag?

It concerns blocking.  As reported in the tar documentation 
  http://www.gnu.org/manual/tar/html_chapter/tar_9.html#SEC125
in the `--blocking-factor' section, when writing to a pipe the
compressed output is blocked out with trailing 0's to a multiple of
512 bytes.

As an ftp archive, we (and many of our mirrors) offer on-the-fly
tarring and gzipping of directories.  In case you are unfamiliar with
this, a person who wants all of the files in the directory `macros/texinfo' 
can issue the ftp command `get macros/texinfo.tar.gz'.  There is no such 
physical file, but the FTP daemon converts the request (as configured
in a configuration file) to a command to run tar with a z option and 
pipe the output to the requestor.

We often get reports from downloaders that gzip is reporting trailing 
garbage.  (It *is* confusing to struggling beginners, I must say.)  As 
your documentation states, this can quite sensibly be regarded as a 
weakness on gunzip's part.  But we have no hope of replacing the gunzip 
of millions of users.  Please, may I request of you a flag that allows
us to turn off this padding behavior?

Allow me to suggest that, with your having moved to a point where your
old option --compress-block is the default, it might be reasonable to
allow folks who need it (us, and our mirrors especially) to turn off
the newer behavior with, perhaps, `--no-compress-block' ?

At the moment we (the three main sites of CTAN) work around this by 
having the FTP daemon call a shell script or a C program, which in 
turn calls tar.  That's not ideal, obviously, but I wouldn't be 
bothering you if the problem was just with us.  We don't have any
control over what our mirrors do, and their behaviour varies widely.
It all ends up with confused and discuoraged users, though.  

It would be a great help to us if some option like this were possible.

Thanks for your consideration,
Jim Hefferon