minitar doesn't support GNU ././@LongName

[halostatue]

Submitted by Curt Sampson (http://rubyforge.org/users/cjs)

GNU tar has a convention for dealing with filenames longer than the 100 character limit imposed by the standard ustar
format. It creates an entry of type 'L' with the filename '././@longname', followed by a 512 byte block containing the
long filename, padded with zeros. The next entry is then the real entry for the file, with a truncated version of the
filename in the name field of the entry header.

The attached patch allows proper reading of tarfiles using this convention. It does not write files using this, however.
It appears that minitar, when writing a file with a name longer than 100 characters, will currently silently truncate
the name.

I suggest adding a test case for this; it would be easy to make a test data file using gnutar.

[halostatue]

I forked the code and placed it on github under http://www.github.com/atoulme/minitar

I made a new release of it (0.5.3) under the name minitar, with this patch. I still need to fix the tests and make it all work.

This is needed for Buildr

[halostatue]

Read is implemented as part of a future 0.6 release. The pre 1.0 versions will not support writing the long-filename format unless someone provides a patch.