How to create a gnu tarball that can be extracted by solaris tar

gnusolaristar

I am maintaining a legacy cygwin (with GNU tar v1.21) system and a legacy Solaris 9 system. The configuration of the Solaris 9 system is fixed and cannot be upgraded (i.e. I can't install gnu tar for Solaris).

I am trying to create a tarball on the cygwin system that can extracted on the Solaris 9 system but unfortunately the directory structure (which is also fixed and cannot be renamed) plus file names exceed 100 characters and I've run into the Great Tar Wars of the last millennium. There is a large (conservative) userbase on the Solaris system so a solution that uses Solaris tar is preferred.

Here are the errors I'm experiencing.

Creating the tar on cygwin:

$ tar -cf dir.tar dir

or 

$ tar -c --posix -f dir.tar dir

Gives the following on Solaris:

$ tar -xif dir.tar
tar: directory checksum errors

And the file names in dir are truncated. (i.e. ignoring checksum errors doesn't help)

How do I create a tarball with long pathnames using GNU tar that can be extracted by Solaris tar?

Edit #2: Unable to use Schily Tar (star)

It appears that Joerg Schilling has been able to emulate the Solaris 7/8/9 tar format and provides a suntar option to create a Solaris tarball using star.

Unfortunately star is not available on cygwin. 🙁

Edit #1: Using –format=posix gives errors when extracting

Errors when extracting –format=posix gnu tarballs using pax on Solaris 9

On cygwin:

$ ls example/this_is_a_path_name_greater_than_one_hundred_characters/when_combined_with_this_file_name_which_is_also_rather_long.txt | wc -m
128
$ tar -c --format=posix -f example.tar example

On Solaris:

$ pax -r -f example.tar
pax: ./PaxHeaders.4440/example : Unknown filetype
pax: example/PaxHeaders.4440/this_is_a_path_name_greater_than_one_hundred_characters : Unknown filetype
pax: example/this_is_a_path_name_greater_than_one_hundred_characters/PaxHeaders.4440/when_combined_with_t : Unknown filetype

Similar errors are given when extracting using Solaris tar.

Best Answer

GNU tar formats suggests tar -c --format=posix or tar -c --format=pax is the only way to create a portable tar file containing path names longer than 255 characters.

The Solaris tar man page doesn't mention supporting that format, but the Solaris pax man page does.

So first, I'd try to create the archive on your Cygwin (or Linux) system using tar -c --format=posix -f dir.tar dir, and to extract it on your Solaris system using pax -r -x pax -f dir.tar, or likely just pax -r -f dir.tar.

Alternatively, if you have cpio installed on both systems, it seems like the crc format supports 1,023 character paths on both systems. That would look something like find -L dir | cpio -o -H crc > dir.cpio to create and cpio -i -d < dir.cpio to extract it.

Finally, you could try adding the -i flag to ignore directory checksum errors when extracting on Solaris, e.g. tar -x -i -f dir.tar. Checksumming problems says this can be needed if any of the file names in the tar archive are non-ASCII.

Other reading:

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