The following is a list of things I would like to see
done with libarchive.  It's sorted roughly in priority;
more feasible and more often-requested items are higher
on the list.  If you think you have time to work on any
of these, please let me know.

* NetBSD's mtree supports various checksum algorithms.
  It would be useful if the reader could verify them and
  the writer could compute them.

* archive_entry_from_file().  This would be very useful.
  Ideally, it would accept a pathname (required) and an
  optional fd.  This will allow it to optimize by using
  fstat() and friends to eliminate races on platforms that
  support those interfaces.

* cpio front-end.  The basic bsdcpio front-end is now
  working.  I'm looking for feedback about what additional
  features are necessary.

* pax front-end.  Once cpio is a little more stable, I plan
  to fork it as the basis of a pax front-end.  The only really
  tricky part will be implementing the header-editing features
  from POSIX 2001 'pax', which will require some changes to
  the libarchive API.

* libarchive on Windows.  Recent changes should allow libarchive
  to port to Visual Studio pretty quickly (large parts of
  archive_write_disk will have to be customized or replaced,
  but that's only about five percent of the entire library).

* bsdtar on Windows.  After libarchive is working on Windows,
  this should be much simpler.  At worst, you can just disable
  features.

* Writing tar sparse entries.  The GNU "1.0" format mentioned above
  sucks a lot less than the old GNU sparse format, so I'm finally
  dropping my objections to sparse file writing.  This requires
  extending archive_entry to support a block list, and will
  require extensive changes to bsdtar to generate block lists.
  The sparse read code will also need to put block lists into
  the entry so that archive-to-archive copies preserve sparseness.

* ISO9660 writing.  Writing ISO9660 requires two passes, and
  libarchive is a single-pass API.  For ISO9660, you can hide
  that behind a temp file, though.  Collect metadata in memory,
  append file bodies (properly padded to 2k sector boundaries)
  to a temp file, then format the directory section and copy
  the file data through at format close.

* Augmenting bsdtar's archive-copy feature:  Being able to "update"
  one archive with the contents of another would be a very
  useful feature, especially for building software packages.
  Consider being able to generate a tar archive of a directory,
  then "fixing" the ownership and permissions based on an
  mtree file.  (Equivalently, reading a tar archive and
  replacing the file contents while retaining the metadata.)
  mtree format, which represents file and directory metadata
  in an easily-editable format, is a natural counterpart to this.

* archive_read_disk:  Currently, libarchive can generate a stream
  of entries from an archive file and can feed entries to an
  archive file or a directory.  The missing corner is pulling
  entries from a directory.  With that, libarchive can provide
  efficient bulk copy services for dir-to-dir, dir-to-archive,
  archive-to-dir, and archive-to-archive.  Right now, the
  read-from-disk capabilities are handled in the client.

* ISO9660 Level 3.  ISO9660 Level 3 supports files over 4GB.

* --split=<limit> option to bsdtar.  This would watch the total output
  size and begin a new archive file whenever <next file size> +
  <total archive size> exceeded <limit>.  Not as robust as
  GNU tar's ability to split an entry across archives, but still
  useful in many situations.

* Filename matching extensions:  ^ to anchor a pattern to the
  beginning of the file, [!...] negated character classes, etc.
