unpackArchive/unpackToDirLazy uses current directory for referencing hardlinks

[ony]

Looks like there is an issue in unpackArchive. I found it out when some of archives that I unpacked with unpackToDirLazy were missing hard links.

What is interesting is that readArchiveFile reads entries successfully and with appropriate type. I was suspecting order between hardlink and target, but bsdtar/tar shows in correct order.

There was another assumption that implementation of writing to filesystem for hard-links doesn't take into account the fact that contrary to symlinks they are referring relative to target dir. But I was able to confirm when I create archive via chain of entriesToBSL -> unpackToDirLazy -> packFiles -> readArchiveBSL there were no loss of entries.

Test run based on PR #2

zsh% cabal v1-build && ./dist/build/libarchive-test/libarchive-test --ignore-dot-hspec
Preprocessing library for libarchive-2.0.0.2..
Building library for libarchive-2.0.0.2..
Preprocessing test suite 'libarchive-test' for libarchive-2.0.0.2..
Building test suite 'libarchive-test' for libarchive-2.0.0.2..

roundtrip
  sucessfully unpacks/packs (test/data/hard-links-bsd.tar)
  with symlinks
    packs/unpacks successfully without loss
    packs/unpacks on filesystem successfully without loss
  with hardlinks
    packs/unpacks successfully without loss
    packs/unpacks on filesystem successfully without loss
  with forward referenced hardlinks
    packs/unpacks successfully without loss
    FIXME
      packs/unpacks on filesystem successfully without loss
        # PENDING: No reason given
  having entry without ownership
    packs/unpacks successfully without loss
      # PENDING: No reason given
  having entry without timestamp
    packs/unpacks successfully without loss
      # PENDING: No reason given
archive samples
  hard-links
    via readArchiveFile
      should succeed
      should contain entry for hard-links/a.txt
      should contain entry for hard-links/b.txt
    via unpackArchive
      should succeed
      should contain hard-links/a.txt FAILED [1]
      should contain hard-links/b.txt

Failures:

  test/Spec.hs:133:25: 
  1) archive samples, hard-links, via unpackArchive, should contain hard-links/a.txt
       expected: True
        but got: False

  To rerun use: --match "/archive samples/hard-links/via unpackArchive/should contain hard-links/a.txt/"

Randomized with seed 1788580387

Finished in 0.0053 seconds
15 examples, 1 failure, 3 pending

zsh% bsdtar tvvf test/data/hard-links-bsd.tar 
drwxr-xr-x  0 nikolay nikolay     0 Dec  1 12:07 hard-links/
-rw-r--r--  0 nikolay nikolay     7 Dec  1 12:07 hard-links/b.txt
hrw-r--r--  0 nikolay nikolay     0 Dec  1 12:07 hard-links/a.txt link to hard-links/b.txt

[ony]

Apparently required conditions to manifest issue:

• presence of hardlink
• current folder doesn't match with one we are unpacking into

Issue reproducible with round-trip test without any sample data now.

Apparently libarchive doesn't have way to specify target directory to unpack libarchive/libarchive#1203 so there is no proper implementations for this. We can continue improving current work-around by not only changing file path but also hardlink target.