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From: gdykes@theory.tn.cornell.edu (Gene Dykes)
Newsgroups: comp.sys.hp
Subject: Serious tar bug
Message-ID: <1991Jan2.221811.26074@batcomputer.tn.cornell.edu>
Date: 2 Jan 91 22:18:11 GMT
Sender: gdykes@batcomputer.tn.cornell.edu (Gene Dykes)
Organization: Cornell Theory Center
Lines: 46

Would somebody please try to duplicate this?  I'm running HPUX 7.0
on a 9000/835.  It would be interesting to know how widespread this
bogosity is...

HP, Please note!

I have uncovered a very serious error in tar.  When told to follow
symbolic links, it sometimes gets confused and starts dumping bizarrely,
even though there is no recursion in the directory structure.

To illustrate, the following commands

    mkdir d1
    cd d1
    mkdir d2 d3
    cd d2
    ln -s ../d3 d4
    cd ../..

produce a tree that looks like this:

				      d1
                                      |\
				      | \
				      |  \
                                     d2  d3
				      |   ^
				      |   |
				      |   |
                                     d4---
				      
				     

The only critical feature here is that there be a directory which is a
symbolic link to a subdirectory of the parent's parent, in this case
d4 points to d3.  Note that this is not recursive.  We would expect that d3
will get dumped twice, but instead, tar gets very confused and starts dumping
all sorts of bizarre areas of the users file system.

To see for yourself, execute the following command after creating the
tree with the above script, but keep your finger poised on your kill key...

tar chvf /dev/null d1

-- 
Gene Dykes, gdykes@theory.tn.cornell.edu